/*
 *  Simplified MAC Kernel (smack) security module
 *
 *  This file contains the smack hook function implementations.
 *
 *  Authors:
 *      Casey Schaufler <casey@schaufler-ca.com>
 *      Jarkko Sakkinen <jarkko.sakkinen@intel.com>
 *
 *  Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com>
 *  Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
 *                Paul Moore <paul@paul-moore.com>
 *  Copyright (C) 2010 Nokia Corporation
 *  Copyright (C) 2011 Intel Corporation.
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License version 2,
 *      as published by the Free Software Foundation.
 */

#include <linux/xattr.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/stat.h>
#include <linux/kd.h>
#include <asm/ioctls.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/dccp.h>
#include <linux/icmpv6.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/pipe_fs_i.h>
#include <net/cipso_ipv4.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <linux/audit.h>
#include <linux/magic.h>
#include <linux/dcache.h>
#include <linux/personality.h>
#include <linux/msg.h>
#include <linux/shm.h>
#include <linux/binfmts.h>
#include <linux/parser.h>
#include "smack.h"

#define TRANS_TRUE      "TRUE"
#define TRANS_TRUE_SIZE 4

#define SMK_CONNECTING  0
#define SMK_RECEIVING   1
#define SMK_SENDING     2

#ifdef SMACK_IPV6_PORT_LABELING
DEFINE_MUTEX(smack_ipv6_lock);
static LIST_HEAD(smk_ipv6_port_list);
#endif
static struct kmem_cache *smack_inode_cache;
int smack_enabled;

static const match_table_t smk_mount_tokens = {
        {Opt_fsdefault, SMK_FSDEFAULT "%s"},
        {Opt_fsfloor, SMK_FSFLOOR "%s"},
        {Opt_fshat, SMK_FSHAT "%s"},
        {Opt_fsroot, SMK_FSROOT "%s"},
        {Opt_fstransmute, SMK_FSTRANS "%s"},
        {Opt_error, NULL},
};

#ifdef CONFIG_SECURITY_SMACK_BRINGUP
static char *smk_bu_mess[] = {
        "Bringup Error",        /* Unused */
        "Bringup",              /* SMACK_BRINGUP_ALLOW */
        "Unconfined Subject",   /* SMACK_UNCONFINED_SUBJECT */
        "Unconfined Object",    /* SMACK_UNCONFINED_OBJECT */
};

static void smk_bu_mode(int mode, char *s)
{
        int i = 0;

        if (mode & MAY_READ)
                s[i++] = 'r';
        if (mode & MAY_WRITE)
                s[i++] = 'w';
        if (mode & MAY_EXEC)
                s[i++] = 'x';
        if (mode & MAY_APPEND)
                s[i++] = 'a';
        if (mode & MAY_TRANSMUTE)
                s[i++] = 't';
        if (mode & MAY_LOCK)
                s[i++] = 'l';
        if (i == 0)
                s[i++] = '-';
        s[i] = '\0';
}
#endif

#ifdef CONFIG_SECURITY_SMACK_BRINGUP
static int smk_bu_note(char *note, struct smack_known *sskp,
                       struct smack_known *oskp, int mode, int rc)
{
        char acc[SMK_NUM_ACCESS_TYPE + 1];

        if (rc <= 0)
                return rc;
        if (rc > SMACK_UNCONFINED_OBJECT)
                rc = 0;

        smk_bu_mode(mode, acc);
        pr_info("Smack %s: (%s %s %s) %s\n", smk_bu_mess[rc],
                sskp->smk_known, oskp->smk_known, acc, note);
        return 0;
}
#else
#define smk_bu_note(note, sskp, oskp, mode, RC) (RC)
#endif

#ifdef CONFIG_SECURITY_SMACK_BRINGUP
static int smk_bu_current(char *note, struct smack_known *oskp,
                          int mode, int rc)
{
        struct task_smack *tsp = current_security();
        char acc[SMK_NUM_ACCESS_TYPE + 1];

        if (rc <= 0)
                return rc;
        if (rc > SMACK_UNCONFINED_OBJECT)
                rc = 0;

        smk_bu_mode(mode, acc);
        pr_info("Smack %s: (%s %s %s) %s %s\n", smk_bu_mess[rc],
                tsp->smk_task->smk_known, oskp->smk_known,
                acc, current->comm, note);
        return 0;
}
#else
#define smk_bu_current(note, oskp, mode, RC) (RC)
#endif

#ifdef CONFIG_SECURITY_SMACK_BRINGUP
static int smk_bu_task(struct task_struct *otp, int mode, int rc)
{
        struct task_smack *tsp = current_security();
        struct smack_known *smk_task = smk_of_task_struct(otp);
        char acc[SMK_NUM_ACCESS_TYPE + 1];

        if (rc <= 0)
                return rc;
        if (rc > SMACK_UNCONFINED_OBJECT)
                rc = 0;

        smk_bu_mode(mode, acc);
        pr_info("Smack %s: (%s %s %s) %s to %s\n", smk_bu_mess[rc],
                tsp->smk_task->smk_known, smk_task->smk_known, acc,
                current->comm, otp->comm);
        return 0;
}
#else
#define smk_bu_task(otp, mode, RC) (RC)
#endif

#ifdef CONFIG_SECURITY_SMACK_BRINGUP
static int smk_bu_inode(struct inode *inode, int mode, int rc)
{
        struct task_smack *tsp = current_security();
        struct inode_smack *isp = inode->i_security;
        char acc[SMK_NUM_ACCESS_TYPE + 1];

        if (isp->smk_flags & SMK_INODE_IMPURE)
                pr_info("Smack Unconfined Corruption: inode=(%s %ld) %s\n",
                        inode->i_sb->s_id, inode->i_ino, current->comm);

        if (rc <= 0)
                return rc;
        if (rc > SMACK_UNCONFINED_OBJECT)
                rc = 0;
        if (rc == SMACK_UNCONFINED_SUBJECT &&
            (mode & (MAY_WRITE | MAY_APPEND)))
                isp->smk_flags |= SMK_INODE_IMPURE;

        smk_bu_mode(mode, acc);

        pr_info("Smack %s: (%s %s %s) inode=(%s %ld) %s\n", smk_bu_mess[rc],
                tsp->smk_task->smk_known, isp->smk_inode->smk_known, acc,
                inode->i_sb->s_id, inode->i_ino, current->comm);
        return 0;
}
#else
#define smk_bu_inode(inode, mode, RC) (RC)
#endif

#ifdef CONFIG_SECURITY_SMACK_BRINGUP
static int smk_bu_file(struct file *file, int mode, int rc)
{
        struct task_smack *tsp = current_security();
        struct smack_known *sskp = tsp->smk_task;
        struct inode *inode = file_inode(file);
        struct inode_smack *isp = inode->i_security;
        char acc[SMK_NUM_ACCESS_TYPE + 1];

        if (isp->smk_flags & SMK_INODE_IMPURE)
                pr_info("Smack Unconfined Corruption: inode=(%s %ld) %s\n",
                        inode->i_sb->s_id, inode->i_ino, current->comm);

        if (rc <= 0)
                return rc;
        if (rc > SMACK_UNCONFINED_OBJECT)
                rc = 0;

        smk_bu_mode(mode, acc);
        pr_info("Smack %s: (%s %s %s) file=(%s %ld %pD) %s\n", smk_bu_mess[rc],
                sskp->smk_known, smk_of_inode(inode)->smk_known, acc,
                inode->i_sb->s_id, inode->i_ino, file,
                current->comm);
        return 0;
}
#else
#define smk_bu_file(file, mode, RC) (RC)
#endif

#ifdef CONFIG_SECURITY_SMACK_BRINGUP
static int smk_bu_credfile(const struct cred *cred, struct file *file,
                                int mode, int rc)
{
        struct task_smack *tsp = cred->security;
        struct smack_known *sskp = tsp->smk_task;
        struct inode *inode = file_inode(file);
        struct inode_smack *isp = inode->i_security;
        char acc[SMK_NUM_ACCESS_TYPE + 1];

        if (isp->smk_flags & SMK_INODE_IMPURE)
                pr_info("Smack Unconfined Corruption: inode=(%s %ld) %s\n",
                        inode->i_sb->s_id, inode->i_ino, current->comm);

        if (rc <= 0)
                return rc;
        if (rc > SMACK_UNCONFINED_OBJECT)
                rc = 0;

        smk_bu_mode(mode, acc);
        pr_info("Smack %s: (%s %s %s) file=(%s %ld %pD) %s\n", smk_bu_mess[rc],
                sskp->smk_known, smk_of_inode(inode)->smk_known, acc,
                inode->i_sb->s_id, inode->i_ino, file,
                current->comm);
        return 0;
}
#else
#define smk_bu_credfile(cred, file, mode, RC) (RC)
#endif

/**
 * smk_fetch - Fetch the smack label from a file.
 * @name: type of the label (attribute)
 * @ip: a pointer to the inode
 * @dp: a pointer to the dentry
 *
 * Returns a pointer to the master list entry for the Smack label,
 * NULL if there was no label to fetch, or an error code.
 */
static struct smack_known *smk_fetch(const char *name, struct inode *ip,
                                        struct dentry *dp)
{
        int rc;
        char *buffer;
        struct smack_known *skp = NULL;

        if (!(ip->i_opflags & IOP_XATTR))
                return ERR_PTR(-EOPNOTSUPP);

        buffer = kzalloc(SMK_LONGLABEL, GFP_KERNEL);
        if (buffer == NULL)
                return ERR_PTR(-ENOMEM);

        rc = __vfs_getxattr(dp, ip, name, buffer, SMK_LONGLABEL);
        if (rc < 0)
                skp = ERR_PTR(rc);
        else if (rc == 0)
                skp = NULL;
        else
                skp = smk_import_entry(buffer, rc);

        kfree(buffer);

        return skp;
}

/**
 * new_inode_smack - allocate an inode security blob
 * @skp: a pointer to the Smack label entry to use in the blob
 *
 * Returns the new blob or NULL if there's no memory available
 */
static struct inode_smack *new_inode_smack(struct smack_known *skp)
{
        struct inode_smack *isp;

        isp = kmem_cache_zalloc(smack_inode_cache, GFP_NOFS);
        if (isp == NULL)
                return NULL;

        isp->smk_inode = skp;
        isp->smk_flags = 0;
        mutex_init(&isp->smk_lock);

        return isp;
}

/**
 * new_task_smack - allocate a task security blob
 * @task: a pointer to the Smack label for the running task
 * @forked: a pointer to the Smack label for the forked task
 * @gfp: type of the memory for the allocation
 *
 * Returns the new blob or NULL if there's no memory available
 */
static struct task_smack *new_task_smack(struct smack_known *task,
                                        struct smack_known *forked, gfp_t gfp)
{
        struct task_smack *tsp;

        tsp = kzalloc(sizeof(struct task_smack), gfp);
        if (tsp == NULL)
                return NULL;

        tsp->smk_task = task;
        tsp->smk_forked = forked;
        INIT_LIST_HEAD(&tsp->smk_rules);
        INIT_LIST_HEAD(&tsp->smk_relabel);
        mutex_init(&tsp->smk_rules_lock);

        return tsp;
}

/**
 * smk_copy_rules - copy a rule set
 * @nhead: new rules header pointer
 * @ohead: old rules header pointer
 * @gfp: type of the memory for the allocation
 *
 * Returns 0 on success, -ENOMEM on error
 */
static int smk_copy_rules(struct list_head *nhead, struct list_head *ohead,
                                gfp_t gfp)
{
        struct smack_rule *nrp;
        struct smack_rule *orp;
        int rc = 0;

        list_for_each_entry_rcu(orp, ohead, list) {
                nrp = kzalloc(sizeof(struct smack_rule), gfp);
                if (nrp == NULL) {
                        rc = -ENOMEM;
                        break;
                }
                *nrp = *orp;
                list_add_rcu(&nrp->list, nhead);
        }
        return rc;
}

/**
 * smk_copy_relabel - copy smk_relabel labels list
 * @nhead: new rules header pointer
 * @ohead: old rules header pointer
 * @gfp: type of the memory for the allocation
 *
 * Returns 0 on success, -ENOMEM on error
 */
static int smk_copy_relabel(struct list_head *nhead, struct list_head *ohead,
                                gfp_t gfp)
{
        struct smack_known_list_elem *nklep;
        struct smack_known_list_elem *oklep;

        list_for_each_entry(oklep, ohead, list) {
                nklep = kzalloc(sizeof(struct smack_known_list_elem), gfp);
                if (nklep == NULL) {
                        smk_destroy_label_list(nhead);
                        return -ENOMEM;
                }
                nklep->smk_label = oklep->smk_label;
                list_add(&nklep->list, nhead);
        }

        return 0;
}

/**
 * smk_ptrace_mode - helper function for converting PTRACE_MODE_* into MAY_*
 * @mode - input mode in form of PTRACE_MODE_*
 *
 * Returns a converted MAY_* mode usable by smack rules
 */
static inline unsigned int smk_ptrace_mode(unsigned int mode)
{
        if (mode & PTRACE_MODE_ATTACH)
                return MAY_READWRITE;
        if (mode & PTRACE_MODE_READ)
                return MAY_READ;

        return 0;
}

/**
 * smk_ptrace_rule_check - helper for ptrace access
 * @tracer: tracer process
 * @tracee_known: label entry of the process that's about to be traced
 * @mode: ptrace attachment mode (PTRACE_MODE_*)
 * @func: name of the function that called us, used for audit
 *
 * Returns 0 on access granted, -error on error
 */
static int smk_ptrace_rule_check(struct task_struct *tracer,
                                 struct smack_known *tracee_known,
                                 unsigned int mode, const char *func)
{
        int rc;
        struct smk_audit_info ad, *saip = NULL;
        struct task_smack *tsp;
        struct smack_known *tracer_known;

        if ((mode & PTRACE_MODE_NOAUDIT) == 0) {
                smk_ad_init(&ad, func, LSM_AUDIT_DATA_TASK);
                smk_ad_setfield_u_tsk(&ad, tracer);
                saip = &ad;
        }

        rcu_read_lock();
        tsp = __task_cred(tracer)->security;
        tracer_known = smk_of_task(tsp);

        if ((mode & PTRACE_MODE_ATTACH) &&
            (smack_ptrace_rule == SMACK_PTRACE_EXACT ||
             smack_ptrace_rule == SMACK_PTRACE_DRACONIAN)) {
                if (tracer_known->smk_known == tracee_known->smk_known)
                        rc = 0;
                else if (smack_ptrace_rule == SMACK_PTRACE_DRACONIAN)
                        rc = -EACCES;
                else if (capable(CAP_SYS_PTRACE))
                        rc = 0;
                else
                        rc = -EACCES;

                if (saip)
                        smack_log(tracer_known->smk_known,
                                  tracee_known->smk_known,
                                  0, rc, saip);

                rcu_read_unlock();
                return rc;
        }

        /* In case of rule==SMACK_PTRACE_DEFAULT or mode==PTRACE_MODE_READ */
        rc = smk_tskacc(tsp, tracee_known, smk_ptrace_mode(mode), saip);

        rcu_read_unlock();
        return rc;
}

/*
 * LSM hooks.
 * We he, that is fun!
 */

/**
 * smack_ptrace_access_check - Smack approval on PTRACE_ATTACH
 * @ctp: child task pointer
 * @mode: ptrace attachment mode (PTRACE_MODE_*)
 *
 * Returns 0 if access is OK, an error code otherwise
 *
 * Do the capability checks.
 */
static int smack_ptrace_access_check(struct task_struct *ctp, unsigned int mode)
{
        struct smack_known *skp;

        skp = smk_of_task_struct(ctp);

        return smk_ptrace_rule_check(current, skp, mode, __func__);
}

/**
 * smack_ptrace_traceme - Smack approval on PTRACE_TRACEME
 * @ptp: parent task pointer
 *
 * Returns 0 if access is OK, an error code otherwise
 *
 * Do the capability checks, and require PTRACE_MODE_ATTACH.
 */
static int smack_ptrace_traceme(struct task_struct *ptp)
{
        int rc;
        struct smack_known *skp;

        skp = smk_of_task(current_security());

        rc = smk_ptrace_rule_check(ptp, skp, PTRACE_MODE_ATTACH, __func__);
        return rc;
}

/**
 * smack_syslog - Smack approval on syslog
 * @type: message type
 *
 * Returns 0 on success, error code otherwise.
 */
static int smack_syslog(int typefrom_file)
{
        int rc = 0;
        struct smack_known *skp = smk_of_current();

        if (smack_privileged(CAP_MAC_OVERRIDE))
                return 0;

        if (smack_syslog_label != NULL && smack_syslog_label != skp)
                rc = -EACCES;

        return rc;
}


/*
 * Superblock Hooks.
 */

/**
 * smack_sb_alloc_security - allocate a superblock blob
 * @sb: the superblock getting the blob
 *
 * Returns 0 on success or -ENOMEM on error.
 */
static int smack_sb_alloc_security(struct super_block *sb)
{
        struct superblock_smack *sbsp;

        sbsp = kzalloc(sizeof(struct superblock_smack), GFP_KERNEL);

        if (sbsp == NULL)
                return -ENOMEM;

        sbsp->smk_root = &smack_known_floor;
        sbsp->smk_default = &smack_known_floor;
        sbsp->smk_floor = &smack_known_floor;
        sbsp->smk_hat = &smack_known_hat;
        /*
         * SMK_SB_INITIALIZED will be zero from kzalloc.
         */
        sb->s_security = sbsp;

        return 0;
}

/**
 * smack_sb_free_security - free a superblock blob
 * @sb: the superblock getting the blob
 *
 */
static void smack_sb_free_security(struct super_block *sb)
{
        kfree(sb->s_security);
        sb->s_security = NULL;
}

/**
 * smack_sb_copy_data - copy mount options data for processing
 * @orig: where to start
 * @smackopts: mount options string
 *
 * Returns 0 on success or -ENOMEM on error.
 *
 * Copy the Smack specific mount options out of the mount
 * options list.
 */
static int smack_sb_copy_data(char *orig, char *smackopts)
{
        char *cp, *commap, *otheropts, *dp;

        otheropts = (char *)get_zeroed_page(GFP_KERNEL);
        if (otheropts == NULL)
                return -ENOMEM;

        for (cp = orig, commap = orig; commap != NULL; cp = commap + 1) {
                if (strstr(cp, SMK_FSDEFAULT) == cp)
                        dp = smackopts;
                else if (strstr(cp, SMK_FSFLOOR) == cp)
                        dp = smackopts;
                else if (strstr(cp, SMK_FSHAT) == cp)
                        dp = smackopts;
                else if (strstr(cp, SMK_FSROOT) == cp)
                        dp = smackopts;
                else if (strstr(cp, SMK_FSTRANS) == cp)
                        dp = smackopts;
                else
                        dp = otheropts;

                commap = strchr(cp, ',');
                if (commap != NULL)
                        *commap = '\0';

                if (*dp != '\0')
                        strcat(dp, ",");
                strcat(dp, cp);
        }

        strcpy(orig, otheropts);
        free_page((unsigned long)otheropts);

        return 0;
}

/**
 * smack_parse_opts_str - parse Smack specific mount options
 * @options: mount options string
 * @opts: where to store converted mount opts
 *
 * Returns 0 on success or -ENOMEM on error.
 *
 * converts Smack specific mount options to generic security option format
 */
static int smack_parse_opts_str(char *options,
                struct security_mnt_opts *opts)
{
        char *p;
        char *fsdefault = NULL;
        char *fsfloor = NULL;
        char *fshat = NULL;
        char *fsroot = NULL;
        char *fstransmute = NULL;
        int rc = -ENOMEM;
        int num_mnt_opts = 0;
        int token;

        opts->num_mnt_opts = 0;

        if (!options)
                return 0;

        while ((p = strsep(&options, ",")) != NULL) {
                substring_t args[MAX_OPT_ARGS];

                if (!*p)
                        continue;

                token = match_token(p, smk_mount_tokens, args);

                switch (token) {
                case Opt_fsdefault:
                        if (fsdefault)
                                goto out_opt_err;
                        fsdefault = match_strdup(&args[0]);
                        if (!fsdefault)
                                goto out_err;
                        break;
                case Opt_fsfloor:
                        if (fsfloor)
                                goto out_opt_err;
                        fsfloor = match_strdup(&args[0]);
                        if (!fsfloor)
                                goto out_err;
                        break;
                case Opt_fshat:
                        if (fshat)
                                goto out_opt_err;
                        fshat = match_strdup(&args[0]);
                        if (!fshat)
                                goto out_err;
                        break;
                case Opt_fsroot:
                        if (fsroot)
                                goto out_opt_err;
                        fsroot = match_strdup(&args[0]);
                        if (!fsroot)
                                goto out_err;
                        break;
                case Opt_fstransmute:
                        if (fstransmute)
                                goto out_opt_err;
                        fstransmute = match_strdup(&args[0]);
                        if (!fstransmute)
                                goto out_err;
                        break;
                default:
                        rc = -EINVAL;
                        pr_warn("Smack:  unknown mount option\n");
                        goto out_err;
                }
        }

        opts->mnt_opts = kcalloc(NUM_SMK_MNT_OPTS, sizeof(char *), GFP_KERNEL);
        if (!opts->mnt_opts)
                goto out_err;

        opts->mnt_opts_flags = kcalloc(NUM_SMK_MNT_OPTS, sizeof(int),
                        GFP_KERNEL);
        if (!opts->mnt_opts_flags)
                goto out_err;

        if (fsdefault) {
                opts->mnt_opts[num_mnt_opts] = fsdefault;
                opts->mnt_opts_flags[num_mnt_opts++] = FSDEFAULT_MNT;
        }
        if (fsfloor) {
                opts->mnt_opts[num_mnt_opts] = fsfloor;
                opts->mnt_opts_flags[num_mnt_opts++] = FSFLOOR_MNT;
        }
        if (fshat) {
                opts->mnt_opts[num_mnt_opts] = fshat;
                opts->mnt_opts_flags[num_mnt_opts++] = FSHAT_MNT;
        }
        if (fsroot) {
                opts->mnt_opts[num_mnt_opts] = fsroot;
                opts->mnt_opts_flags[num_mnt_opts++] = FSROOT_MNT;
        }
        if (fstransmute) {
                opts->mnt_opts[num_mnt_opts] = fstransmute;
                opts->mnt_opts_flags[num_mnt_opts++] = FSTRANS_MNT;
        }

        opts->num_mnt_opts = num_mnt_opts;
        return 0;

out_opt_err:
        rc = -EINVAL;
        pr_warn("Smack: duplicate mount options\n");

out_err:
        kfree(fsdefault);
        kfree(fsfloor);
        kfree(fshat);
        kfree(fsroot);
        kfree(fstransmute);
        return rc;
}

/**
 * smack_set_mnt_opts - set Smack specific mount options
 * @sb: the file system superblock
 * @opts: Smack mount options
 * @kern_flags: mount option from kernel space or user space
 * @set_kern_flags: where to store converted mount opts
 *
 * Returns 0 on success, an error code on failure
 *
 * Allow filesystems with binary mount data to explicitly set Smack mount
 * labels.
 */
static int smack_set_mnt_opts(struct super_block *sb,
                struct security_mnt_opts *opts,
                unsigned long kern_flags,
                unsigned long *set_kern_flags)
{
        struct dentry *root = sb->s_root;
        struct inode *inode = d_backing_inode(root);
        struct superblock_smack *sp = sb->s_security;
        struct inode_smack *isp;
        struct smack_known *skp;
        int i;
        int num_opts = opts->num_mnt_opts;
        int transmute = 0;

        if (sp->smk_flags & SMK_SB_INITIALIZED)
                return 0;

        if (!smack_privileged(CAP_MAC_ADMIN)) {
                /*
                 * Unprivileged mounts don't get to specify Smack values.
                 */
                if (num_opts)
                        return -EPERM;
                /*
                 * Unprivileged mounts get root and default from the caller.
                 */
                skp = smk_of_current();
                sp->smk_root = skp;
                sp->smk_default = skp;
                /*
                 * For a handful of fs types with no user-controlled
                 * backing store it's okay to trust security labels
                 * in the filesystem. The rest are untrusted.
                 */
                if (sb->s_user_ns != &init_user_ns &&
                    sb->s_magic != SYSFS_MAGIC && sb->s_magic != TMPFS_MAGIC &&
                    sb->s_magic != RAMFS_MAGIC) {
                        transmute = 1;
                        sp->smk_flags |= SMK_SB_UNTRUSTED;
                }
        }

        sp->smk_flags |= SMK_SB_INITIALIZED;

        for (i = 0; i < num_opts; i++) {
                switch (opts->mnt_opts_flags[i]) {
                case FSDEFAULT_MNT:
                        skp = smk_import_entry(opts->mnt_opts[i], 0);
                        if (IS_ERR(skp))
                                return PTR_ERR(skp);
                        sp->smk_default = skp;
                        break;
                case FSFLOOR_MNT:
                        skp = smk_import_entry(opts->mnt_opts[i], 0);
                        if (IS_ERR(skp))
                                return PTR_ERR(skp);
                        sp->smk_floor = skp;
                        break;
                case FSHAT_MNT:
                        skp = smk_import_entry(opts->mnt_opts[i], 0);
                        if (IS_ERR(skp))
                                return PTR_ERR(skp);
                        sp->smk_hat = skp;
                        break;
                case FSROOT_MNT:
                        skp = smk_import_entry(opts->mnt_opts[i], 0);
                        if (IS_ERR(skp))
                                return PTR_ERR(skp);
                        sp->smk_root = skp;
                        break;
                case FSTRANS_MNT:
                        skp = smk_import_entry(opts->mnt_opts[i], 0);
                        if (IS_ERR(skp))
                                return PTR_ERR(skp);
                        sp->smk_root = skp;
                        transmute = 1;
                        break;
                default:
                        break;
                }
        }

        /*
         * Initialize the root inode.
         */
        isp = inode->i_security;
        if (isp == NULL) {
                isp = new_inode_smack(sp->smk_root);
                if (isp == NULL)
                        return -ENOMEM;
                inode->i_security = isp;
        } else
                isp->smk_inode = sp->smk_root;

        if (transmute)
                isp->smk_flags |= SMK_INODE_TRANSMUTE;

        return 0;
}

/**
 * smack_sb_kern_mount - Smack specific mount processing
 * @sb: the file system superblock
 * @flags: the mount flags
 * @data: the smack mount options
 *
 * Returns 0 on success, an error code on failure
 */
static int smack_sb_kern_mount(struct super_block *sb, int flags, void *data)
{
        int rc = 0;
        char *options = data;
        struct security_mnt_opts opts;

        security_init_mnt_opts(&opts);

        if (!options)
                goto out;

        rc = smack_parse_opts_str(options, &opts);
        if (rc)
                goto out_err;

out:
        rc = smack_set_mnt_opts(sb, &opts, 0, NULL);

out_err:
        security_free_mnt_opts(&opts);
        return rc;
}

/**
 * smack_sb_statfs - Smack check on statfs
 * @dentry: identifies the file system in question
 *
 * Returns 0 if current can read the floor of the filesystem,
 * and error code otherwise
 */
static int smack_sb_statfs(struct dentry *dentry)
{
        struct superblock_smack *sbp = dentry->d_sb->s_security;
        int rc;
        struct smk_audit_info ad;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
        smk_ad_setfield_u_fs_path_dentry(&ad, dentry);

        rc = smk_curacc(sbp->smk_floor, MAY_READ, &ad);
        rc = smk_bu_current("statfs", sbp->smk_floor, MAY_READ, rc);
        return rc;
}

/*
 * BPRM hooks
 */

/**
 * smack_bprm_set_creds - set creds for exec
 * @bprm: the exec information
 *
 * Returns 0 if it gets a blob, -EPERM if exec forbidden and -ENOMEM otherwise
 */
static int smack_bprm_set_creds(struct linux_binprm *bprm)
{
        struct inode *inode = file_inode(bprm->file);
        struct task_smack *bsp = bprm->cred->security;
        struct inode_smack *isp;
        struct superblock_smack *sbsp;
        int rc;

        if (bprm->called_set_creds)
                return 0;

        isp = inode->i_security;
        if (isp->smk_task == NULL || isp->smk_task == bsp->smk_task)
                return 0;

        sbsp = inode->i_sb->s_security;
        if ((sbsp->smk_flags & SMK_SB_UNTRUSTED) &&
            isp->smk_task != sbsp->smk_root)
                return 0;

        if (bprm->unsafe & LSM_UNSAFE_PTRACE) {
                struct task_struct *tracer;
                rc = 0;

                rcu_read_lock();
                tracer = ptrace_parent(current);
                if (likely(tracer != NULL))
                        rc = smk_ptrace_rule_check(tracer,
                                                   isp->smk_task,
                                                   PTRACE_MODE_ATTACH,
                                                   __func__);
                rcu_read_unlock();

                if (rc != 0)
                        return rc;
        } else if (bprm->unsafe)
                return -EPERM;

        bsp->smk_task = isp->smk_task;
        bprm->per_clear |= PER_CLEAR_ON_SETID;

        /* Decide if this is a secure exec. */
        if (bsp->smk_task != bsp->smk_forked)
                bprm->secureexec = 1;

        return 0;
}

/*
 * Inode hooks
 */

/**
 * smack_inode_alloc_security - allocate an inode blob
 * @inode: the inode in need of a blob
 *
 * Returns 0 if it gets a blob, -ENOMEM otherwise
 */
static int smack_inode_alloc_security(struct inode *inode)
{
        struct smack_known *skp = smk_of_current();

        inode->i_security = new_inode_smack(skp);
        if (inode->i_security == NULL)
                return -ENOMEM;
        return 0;
}

/**
 * smack_inode_free_rcu - Free inode_smack blob from cache
 * @head: the rcu_head for getting inode_smack pointer
 *
 *  Call back function called from call_rcu() to free
 *  the i_security blob pointer in inode
 */
static void smack_inode_free_rcu(struct rcu_head *head)
{
        struct inode_smack *issp;

        issp = container_of(head, struct inode_smack, smk_rcu);
        kmem_cache_free(smack_inode_cache, issp);
}

/**
 * smack_inode_free_security - free an inode blob using call_rcu()
 * @inode: the inode with a blob
 *
 * Clears the blob pointer in inode using RCU

 */
static void smack_inode_free_security(struct inode *inode)
{
        struct inode_smack *issp = inode->i_security;

        /*
         * The inode may still be referenced in a path walk and
         * a call to smack_inode_permission() can be made
         * after smack_inode_free_security() is called.
         * To avoid race condition free the i_security via RCU
         * and leave the current inode->i_security pointer intact.
         * The inode will be freed after the RCU grace period too.
         */
        call_rcu(&issp->smk_rcu, smack_inode_free_rcu);
}

/**
 * smack_inode_init_security - copy out the smack from an inode
 * @inode: the newly created inode
 * @dir: containing directory object
 * @qstr: unused
 * @name: where to put the attribute name
 * @value: where to put the attribute value
 * @len: where to put the length of the attribute
 *
 * Returns 0 if it all works out, -ENOMEM if there's no memory
 */
static int smack_inode_init_security(struct inode *inode, struct inode *dir,
                                     const struct qstr *qstr, const char **name,
                                     void **value, size_t *len)
{
        struct inode_smack *issp = inode->i_security;
        struct smack_known *skp = smk_of_current();
        struct smack_known *isp = smk_of_inode(inode);
        struct smack_known *dsp = smk_of_inode(dir);
        int may;

        if (name)
                *name = XATTR_SMACK_SUFFIX;

        if (value && len) {
                rcu_read_lock();
                may = smk_access_entry(skp->smk_known, dsp->smk_known,
                                       &skp->smk_rules);
                rcu_read_unlock();

                /*
                 * If the access rule allows transmutation and
                 * the directory requests transmutation then
                 * by all means transmute.
                 * Mark the inode as changed.
                 */
                if (may > 0 && ((may & MAY_TRANSMUTE) != 0) &&
                    smk_inode_transmutable(dir)) {
                        isp = dsp;
                        issp->smk_flags |= SMK_INODE_CHANGED;
                }

                *value = kstrdup(isp->smk_known, GFP_NOFS);
                if (*value == NULL)
                        return -ENOMEM;

                *len = strlen(isp->smk_known);
        }

        return 0;
}

/**
 * smack_inode_link - Smack check on link
 * @old_dentry: the existing object
 * @dir: unused
 * @new_dentry: the new object
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_link(struct dentry *old_dentry, struct inode *dir,
                            struct dentry *new_dentry)
{
        struct smack_known *isp;
        struct smk_audit_info ad;
        int rc;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
        smk_ad_setfield_u_fs_path_dentry(&ad, old_dentry);

        isp = smk_of_inode(d_backing_inode(old_dentry));
        rc = smk_curacc(isp, MAY_WRITE, &ad);
        rc = smk_bu_inode(d_backing_inode(old_dentry), MAY_WRITE, rc);

        if (rc == 0 && d_is_positive(new_dentry)) {
                isp = smk_of_inode(d_backing_inode(new_dentry));
                smk_ad_setfield_u_fs_path_dentry(&ad, new_dentry);
                rc = smk_curacc(isp, MAY_WRITE, &ad);
                rc = smk_bu_inode(d_backing_inode(new_dentry), MAY_WRITE, rc);
        }

        return rc;
}

/**
 * smack_inode_unlink - Smack check on inode deletion
 * @dir: containing directory object
 * @dentry: file to unlink
 *
 * Returns 0 if current can write the containing directory
 * and the object, error code otherwise
 */
static int smack_inode_unlink(struct inode *dir, struct dentry *dentry)
{
        struct inode *ip = d_backing_inode(dentry);
        struct smk_audit_info ad;
        int rc;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
        smk_ad_setfield_u_fs_path_dentry(&ad, dentry);

        /*
         * You need write access to the thing you're unlinking
         */
        rc = smk_curacc(smk_of_inode(ip), MAY_WRITE, &ad);
        rc = smk_bu_inode(ip, MAY_WRITE, rc);
        if (rc == 0) {
                /*
                 * You also need write access to the containing directory
                 */
                smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_INODE);
                smk_ad_setfield_u_fs_inode(&ad, dir);
                rc = smk_curacc(smk_of_inode(dir), MAY_WRITE, &ad);
                rc = smk_bu_inode(dir, MAY_WRITE, rc);
        }
        return rc;
}

/**
 * smack_inode_rmdir - Smack check on directory deletion
 * @dir: containing directory object
 * @dentry: directory to unlink
 *
 * Returns 0 if current can write the containing directory
 * and the directory, error code otherwise
 */
static int smack_inode_rmdir(struct inode *dir, struct dentry *dentry)
{
        struct smk_audit_info ad;
        int rc;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
        smk_ad_setfield_u_fs_path_dentry(&ad, dentry);

        /*
         * You need write access to the thing you're removing
         */
        rc = smk_curacc(smk_of_inode(d_backing_inode(dentry)), MAY_WRITE, &ad);
        rc = smk_bu_inode(d_backing_inode(dentry), MAY_WRITE, rc);
        if (rc == 0) {
                /*
                 * You also need write access to the containing directory
                 */
                smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_INODE);
                smk_ad_setfield_u_fs_inode(&ad, dir);
                rc = smk_curacc(smk_of_inode(dir), MAY_WRITE, &ad);
                rc = smk_bu_inode(dir, MAY_WRITE, rc);
        }

        return rc;
}

/**
 * smack_inode_rename - Smack check on rename
 * @old_inode: unused
 * @old_dentry: the old object
 * @new_inode: unused
 * @new_dentry: the new object
 *
 * Read and write access is required on both the old and
 * new directories.
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_rename(struct inode *old_inode,
                              struct dentry *old_dentry,
                              struct inode *new_inode,
                              struct dentry *new_dentry)
{
        int rc;
        struct smack_known *isp;
        struct smk_audit_info ad;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
        smk_ad_setfield_u_fs_path_dentry(&ad, old_dentry);

        isp = smk_of_inode(d_backing_inode(old_dentry));
        rc = smk_curacc(isp, MAY_READWRITE, &ad);
        rc = smk_bu_inode(d_backing_inode(old_dentry), MAY_READWRITE, rc);

        if (rc == 0 && d_is_positive(new_dentry)) {
                isp = smk_of_inode(d_backing_inode(new_dentry));
                smk_ad_setfield_u_fs_path_dentry(&ad, new_dentry);
                rc = smk_curacc(isp, MAY_READWRITE, &ad);
                rc = smk_bu_inode(d_backing_inode(new_dentry), MAY_READWRITE, rc);
        }
        return rc;
}

/**
 * smack_inode_permission - Smack version of permission()
 * @inode: the inode in question
 * @mask: the access requested
 *
 * This is the important Smack hook.
 *
 * Returns 0 if access is permitted, -EACCES otherwise
 */
static int smack_inode_permission(struct inode *inode, int mask)
{
        struct superblock_smack *sbsp = inode->i_sb->s_security;
        struct smk_audit_info ad;
        int no_block = mask & MAY_NOT_BLOCK;
        int rc;

        mask &= (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND);
        /*
         * No permission to check. Existence test. Yup, it's there.
         */
        if (mask == 0)
                return 0;

        if (sbsp->smk_flags & SMK_SB_UNTRUSTED) {
                if (smk_of_inode(inode) != sbsp->smk_root)
                        return -EACCES;
        }

        /* May be droppable after audit */
        if (no_block)
                return -ECHILD;
        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_INODE);
        smk_ad_setfield_u_fs_inode(&ad, inode);
        rc = smk_curacc(smk_of_inode(inode), mask, &ad);
        rc = smk_bu_inode(inode, mask, rc);
        return rc;
}

/**
 * smack_inode_setattr - Smack check for setting attributes
 * @dentry: the object
 * @iattr: for the force flag
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_setattr(struct dentry *dentry, struct iattr *iattr)
{
        struct smk_audit_info ad;
        int rc;

        /*
         * Need to allow for clearing the setuid bit.
         */
        if (iattr->ia_valid & ATTR_FORCE)
                return 0;
        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
        smk_ad_setfield_u_fs_path_dentry(&ad, dentry);

        rc = smk_curacc(smk_of_inode(d_backing_inode(dentry)), MAY_WRITE, &ad);
        rc = smk_bu_inode(d_backing_inode(dentry), MAY_WRITE, rc);
        return rc;
}

/**
 * smack_inode_getattr - Smack check for getting attributes
 * @mnt: vfsmount of the object
 * @dentry: the object
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_getattr(const struct path *path)
{
        struct smk_audit_info ad;
        struct inode *inode = d_backing_inode(path->dentry);
        int rc;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
        smk_ad_setfield_u_fs_path(&ad, *path);
        rc = smk_curacc(smk_of_inode(inode), MAY_READ, &ad);
        rc = smk_bu_inode(inode, MAY_READ, rc);
        return rc;
}

/**
 * smack_inode_setxattr - Smack check for setting xattrs
 * @dentry: the object
 * @name: name of the attribute
 * @value: value of the attribute
 * @size: size of the value
 * @flags: unused
 *
 * This protects the Smack attribute explicitly.
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_setxattr(struct dentry *dentry, const char *name,
                                const void *value, size_t size, int flags)
{
        struct smk_audit_info ad;
        struct smack_known *skp;
        int check_priv = 0;
        int check_import = 0;
        int check_star = 0;
        int rc = 0;

        /*
         * Check label validity here so import won't fail in post_setxattr
         */
        if (strcmp(name, XATTR_NAME_SMACK) == 0 ||
            strcmp(name, XATTR_NAME_SMACKIPIN) == 0 ||
            strcmp(name, XATTR_NAME_SMACKIPOUT) == 0) {
                check_priv = 1;
                check_import = 1;
        } else if (strcmp(name, XATTR_NAME_SMACKEXEC) == 0 ||
                   strcmp(name, XATTR_NAME_SMACKMMAP) == 0) {
                check_priv = 1;
                check_import = 1;
                check_star = 1;
        } else if (strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0) {
                check_priv = 1;
                if (size != TRANS_TRUE_SIZE ||
                    strncmp(value, TRANS_TRUE, TRANS_TRUE_SIZE) != 0)
                        rc = -EINVAL;
        } else
                rc = cap_inode_setxattr(dentry, name, value, size, flags);

        if (check_priv && !smack_privileged(CAP_MAC_ADMIN))
                rc = -EPERM;

        if (rc == 0 && check_import) {
                skp = size ? smk_import_entry(value, size) : NULL;
                if (IS_ERR(skp))
                        rc = PTR_ERR(skp);
                else if (skp == NULL || (check_star &&
                    (skp == &smack_known_star || skp == &smack_known_web)))
                        rc = -EINVAL;
        }

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
        smk_ad_setfield_u_fs_path_dentry(&ad, dentry);

        if (rc == 0) {
                rc = smk_curacc(smk_of_inode(d_backing_inode(dentry)), MAY_WRITE, &ad);
                rc = smk_bu_inode(d_backing_inode(dentry), MAY_WRITE, rc);
        }

        return rc;
}

/**
 * smack_inode_post_setxattr - Apply the Smack update approved above
 * @dentry: object
 * @name: attribute name
 * @value: attribute value
 * @size: attribute size
 * @flags: unused
 *
 * Set the pointer in the inode blob to the entry found
 * in the master label list.
 */
static void smack_inode_post_setxattr(struct dentry *dentry, const char *name,
                                      const void *value, size_t size, int flags)
{
        struct smack_known *skp;
        struct inode_smack *isp = d_backing_inode(dentry)->i_security;

        if (strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0) {
                isp->smk_flags |= SMK_INODE_TRANSMUTE;
                return;
        }

        if (strcmp(name, XATTR_NAME_SMACK) == 0) {
                skp = smk_import_entry(value, size);
                if (!IS_ERR(skp))
                        isp->smk_inode = skp;
        } else if (strcmp(name, XATTR_NAME_SMACKEXEC) == 0) {
                skp = smk_import_entry(value, size);
                if (!IS_ERR(skp))
                        isp->smk_task = skp;
        } else if (strcmp(name, XATTR_NAME_SMACKMMAP) == 0) {
                skp = smk_import_entry(value, size);
                if (!IS_ERR(skp))
                        isp->smk_mmap = skp;
        }

        return;
}

/**
 * smack_inode_getxattr - Smack check on getxattr
 * @dentry: the object
 * @name: unused
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_getxattr(struct dentry *dentry, const char *name)
{
        struct smk_audit_info ad;
        int rc;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
        smk_ad_setfield_u_fs_path_dentry(&ad, dentry);

        rc = smk_curacc(smk_of_inode(d_backing_inode(dentry)), MAY_READ, &ad);
        rc = smk_bu_inode(d_backing_inode(dentry), MAY_READ, rc);
        return rc;
}

/**
 * smack_inode_removexattr - Smack check on removexattr
 * @dentry: the object
 * @name: name of the attribute
 *
 * Removing the Smack attribute requires CAP_MAC_ADMIN
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_removexattr(struct dentry *dentry, const char *name)
{
        struct inode_smack *isp;
        struct smk_audit_info ad;
        int rc = 0;

        if (strcmp(name, XATTR_NAME_SMACK) == 0 ||
            strcmp(name, XATTR_NAME_SMACKIPIN) == 0 ||
            strcmp(name, XATTR_NAME_SMACKIPOUT) == 0 ||
            strcmp(name, XATTR_NAME_SMACKEXEC) == 0 ||
            strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0 ||
            strcmp(name, XATTR_NAME_SMACKMMAP) == 0) {
                if (!smack_privileged(CAP_MAC_ADMIN))
                        rc = -EPERM;
        } else
                rc = cap_inode_removexattr(dentry, name);

        if (rc != 0)
                return rc;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
        smk_ad_setfield_u_fs_path_dentry(&ad, dentry);

        rc = smk_curacc(smk_of_inode(d_backing_inode(dentry)), MAY_WRITE, &ad);
        rc = smk_bu_inode(d_backing_inode(dentry), MAY_WRITE, rc);
        if (rc != 0)
                return rc;

        isp = d_backing_inode(dentry)->i_security;
        /*
         * Don't do anything special for these.
         *      XATTR_NAME_SMACKIPIN
         *      XATTR_NAME_SMACKIPOUT
         */
        if (strcmp(name, XATTR_NAME_SMACK) == 0) {
                struct super_block *sbp = dentry->d_sb;
                struct superblock_smack *sbsp = sbp->s_security;

                isp->smk_inode = sbsp->smk_default;
        } else if (strcmp(name, XATTR_NAME_SMACKEXEC) == 0)
                isp->smk_task = NULL;
        else if (strcmp(name, XATTR_NAME_SMACKMMAP) == 0)
                isp->smk_mmap = NULL;
        else if (strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0)
                isp->smk_flags &= ~SMK_INODE_TRANSMUTE;

        return 0;
}

/**
 * smack_inode_getsecurity - get smack xattrs
 * @inode: the object
 * @name: attribute name
 * @buffer: where to put the result
 * @alloc: duplicate memory
 *
 * Returns the size of the attribute or an error code
 */
static int smack_inode_getsecurity(struct inode *inode,
                                   const char *name, void **buffer,
                                   bool alloc)
{
        struct socket_smack *ssp;
        struct socket *sock;
        struct super_block *sbp;
        struct inode *ip = (struct inode *)inode;
        struct smack_known *isp;

        if (strcmp(name, XATTR_SMACK_SUFFIX) == 0)
                isp = smk_of_inode(inode);
        else {
                /*
                 * The rest of the Smack xattrs are only on sockets.
                 */
                sbp = ip->i_sb;
                if (sbp->s_magic != SOCKFS_MAGIC)
                        return -EOPNOTSUPP;

                sock = SOCKET_I(ip);
                if (sock == NULL || sock->sk == NULL)
                        return -EOPNOTSUPP;

                ssp = sock->sk->sk_security;

                if (strcmp(name, XATTR_SMACK_IPIN) == 0)
                        isp = ssp->smk_in;
                else if (strcmp(name, XATTR_SMACK_IPOUT) == 0)
                        isp = ssp->smk_out;
                else
                        return -EOPNOTSUPP;
        }

        if (alloc) {
                *buffer = kstrdup(isp->smk_known, GFP_KERNEL);
                if (*buffer == NULL)
                        return -ENOMEM;
        }

        return strlen(isp->smk_known);
}


/**
 * smack_inode_listsecurity - list the Smack attributes
 * @inode: the object
 * @buffer: where they go
 * @buffer_size: size of buffer
 */
static int smack_inode_listsecurity(struct inode *inode, char *buffer,
                                    size_t buffer_size)
{
        int len = sizeof(XATTR_NAME_SMACK);

        if (buffer != NULL && len <= buffer_size)
                memcpy(buffer, XATTR_NAME_SMACK, len);

        return len;
}

/**
 * smack_inode_getsecid - Extract inode's security id
 * @inode: inode to extract the info from
 * @secid: where result will be saved
 */
static void smack_inode_getsecid(struct inode *inode, u32 *secid)
{
        struct smack_known *skp = smk_of_inode(inode);

        *secid = skp->smk_secid;
}

/*
 * File Hooks
 */

/*
 * There is no smack_file_permission hook
 *
 * Should access checks be done on each read or write?
 * UNICOS and SELinux say yes.
 * Trusted Solaris, Trusted Irix, and just about everyone else says no.
 *
 * I'll say no for now. Smack does not do the frequent
 * label changing that SELinux does.
 */

/**
 * smack_file_alloc_security - assign a file security blob
 * @file: the object
 *
 * The security blob for a file is a pointer to the master
 * label list, so no allocation is done.
 *
 * f_security is the owner security information. It
 * isn't used on file access checks, it's for send_sigio.
 *
 * Returns 0
 */
static int smack_file_alloc_security(struct file *file)
{
        struct smack_known *skp = smk_of_current();

        file->f_security = skp;
        return 0;
}

/**
 * smack_file_free_security - clear a file security blob
 * @file: the object
 *
 * The security blob for a file is a pointer to the master
 * label list, so no memory is freed.
 */
static void smack_file_free_security(struct file *file)
{
        file->f_security = NULL;
}

/**
 * smack_file_ioctl - Smack check on ioctls
 * @file: the object
 * @cmd: what to do
 * @arg: unused
 *
 * Relies heavily on the correct use of the ioctl command conventions.
 *
 * Returns 0 if allowed, error code otherwise
 */
static int smack_file_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
        int rc = 0;
        struct smk_audit_info ad;
        struct inode *inode = file_inode(file);

        if (unlikely(IS_PRIVATE(inode)))
                return 0;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
        smk_ad_setfield_u_fs_path(&ad, file->f_path);

        if (_IOC_DIR(cmd) & _IOC_WRITE) {
                rc = smk_curacc(smk_of_inode(inode), MAY_WRITE, &ad);
                rc = smk_bu_file(file, MAY_WRITE, rc);
        }

        if (rc == 0 && (_IOC_DIR(cmd) & _IOC_READ)) {
                rc = smk_curacc(smk_of_inode(inode), MAY_READ, &ad);
                rc = smk_bu_file(file, MAY_READ, rc);
        }

        return rc;
}

/**
 * smack_file_lock - Smack check on file locking
 * @file: the object
 * @cmd: unused
 *
 * Returns 0 if current has lock access, error code otherwise
 */
static int smack_file_lock(struct file *file, unsigned int cmd)
{
        struct smk_audit_info ad;
        int rc;
        struct inode *inode = file_inode(file);

        if (unlikely(IS_PRIVATE(inode)))
                return 0;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
        smk_ad_setfield_u_fs_path(&ad, file->f_path);
        rc = smk_curacc(smk_of_inode(inode), MAY_LOCK, &ad);
        rc = smk_bu_file(file, MAY_LOCK, rc);
        return rc;
}

/**
 * smack_file_fcntl - Smack check on fcntl
 * @file: the object
 * @cmd: what action to check
 * @arg: unused
 *
 * Generally these operations are harmless.
 * File locking operations present an obvious mechanism
 * for passing information, so they require write access.
 *
 * Returns 0 if current has access, error code otherwise
 */
static int smack_file_fcntl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
        struct smk_audit_info ad;
        int rc = 0;
        struct inode *inode = file_inode(file);

        if (unlikely(IS_PRIVATE(inode)))
                return 0;

        switch (cmd) {
        case F_GETLK:
                break;
        case F_SETLK:
        case F_SETLKW:
                smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
                smk_ad_setfield_u_fs_path(&ad, file->f_path);
                rc = smk_curacc(smk_of_inode(inode), MAY_LOCK, &ad);
                rc = smk_bu_file(file, MAY_LOCK, rc);
                break;
        case F_SETOWN:
        case F_SETSIG:
                smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
                smk_ad_setfield_u_fs_path(&ad, file->f_path);
                rc = smk_curacc(smk_of_inode(inode), MAY_WRITE, &ad);
                rc = smk_bu_file(file, MAY_WRITE, rc);
                break;
        default:
                break;
        }

        return rc;
}

/**
 * smack_mmap_file :
 * Check permissions for a mmap operation.  The @file may be NULL, e.g.
 * if mapping anonymous memory.
 * @file contains the file structure for file to map (may be NULL).
 * @reqprot contains the protection requested by the application.
 * @prot contains the protection that will be applied by the kernel.
 * @flags contains the operational flags.
 * Return 0 if permission is granted.
 */
static int smack_mmap_file(struct file *file,
                           unsigned long reqprot, unsigned long prot,
                           unsigned long flags)
{
        struct smack_known *skp;
        struct smack_known *mkp;
        struct smack_rule *srp;
        struct task_smack *tsp;
        struct smack_known *okp;
        struct inode_smack *isp;
        struct superblock_smack *sbsp;
        int may;
        int mmay;
        int tmay;
        int rc;

        if (file == NULL)
                return 0;

        if (unlikely(IS_PRIVATE(file_inode(file))))
                return 0;

        isp = file_inode(file)->i_security;
        if (isp->smk_mmap == NULL)
                return 0;
        sbsp = file_inode(file)->i_sb->s_security;
        if (sbsp->smk_flags & SMK_SB_UNTRUSTED &&
            isp->smk_mmap != sbsp->smk_root)
                return -EACCES;
        mkp = isp->smk_mmap;

        tsp = current_security();
        skp = smk_of_current();
        rc = 0;

        rcu_read_lock();
        /*
         * For each Smack rule associated with the subject
         * label verify that the SMACK64MMAP also has access
         * to that rule's object label.
         */
        list_for_each_entry_rcu(srp, &skp->smk_rules, list) {
                okp = srp->smk_object;
                /*
                 * Matching labels always allows access.
                 */
                if (mkp->smk_known == okp->smk_known)
                        continue;
                /*
                 * If there is a matching local rule take
                 * that into account as well.
                 */
                may = smk_access_entry(srp->smk_subject->smk_known,
                                       okp->smk_known,
                                       &tsp->smk_rules);
                if (may == -ENOENT)
                        may = srp->smk_access;
                else
                        may &= srp->smk_access;
                /*
                 * If may is zero the SMACK64MMAP subject can't
                 * possibly have less access.
                 */
                if (may == 0)
                        continue;

                /*
                 * Fetch the global list entry.
                 * If there isn't one a SMACK64MMAP subject
                 * can't have as much access as current.
                 */
                mmay = smk_access_entry(mkp->smk_known, okp->smk_known,
                                        &mkp->smk_rules);
                if (mmay == -ENOENT) {
                        rc = -EACCES;
                        break;
                }
                /*
                 * If there is a local entry it modifies the
                 * potential access, too.
                 */
                tmay = smk_access_entry(mkp->smk_known, okp->smk_known,
                                        &tsp->smk_rules);
                if (tmay != -ENOENT)
                        mmay &= tmay;

                /*
                 * If there is any access available to current that is
                 * not available to a SMACK64MMAP subject
                 * deny access.
                 */
                if ((may | mmay) != mmay) {
                        rc = -EACCES;
                        break;
                }
        }

        rcu_read_unlock();

        return rc;
}

/**
 * smack_file_set_fowner - set the file security blob value
 * @file: object in question
 *
 */
static void smack_file_set_fowner(struct file *file)
{
        file->f_security = smk_of_current();
}

/**
 * smack_file_send_sigiotask - Smack on sigio
 * @tsk: The target task
 * @fown: the object the signal come from
 * @signum: unused
 *
 * Allow a privileged task to get signals even if it shouldn't
 *
 * Returns 0 if a subject with the object's smack could
 * write to the task, an error code otherwise.
 */
static int smack_file_send_sigiotask(struct task_struct *tsk,
                                     struct fown_struct *fown, int signum)
{
        struct smack_known *skp;
        struct smack_known *tkp = smk_of_task(tsk->cred->security);
        struct file *file;
        int rc;
        struct smk_audit_info ad;

        /*
         * struct fown_struct is never outside the context of a struct file
         */
        file = container_of(fown, struct file, f_owner);

        /* we don't log here as rc can be overriden */
        skp = file->f_security;
        rc = smk_access(skp, tkp, MAY_DELIVER, NULL);
        rc = smk_bu_note("sigiotask", skp, tkp, MAY_DELIVER, rc);
        if (rc != 0 && has_capability(tsk, CAP_MAC_OVERRIDE))
                rc = 0;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
        smk_ad_setfield_u_tsk(&ad, tsk);
        smack_log(skp->smk_known, tkp->smk_known, MAY_DELIVER, rc, &ad);
        return rc;
}

/**
 * smack_file_receive - Smack file receive check
 * @file: the object
 *
 * Returns 0 if current has access, error code otherwise
 */
static int smack_file_receive(struct file *file)
{
        int rc;
        int may = 0;
        struct smk_audit_info ad;
        struct inode *inode = file_inode(file);
        struct socket *sock;
        struct task_smack *tsp;
        struct socket_smack *ssp;

        if (unlikely(IS_PRIVATE(inode)))
                return 0;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
        smk_ad_setfield_u_fs_path(&ad, file->f_path);

        if (inode->i_sb->s_magic == SOCKFS_MAGIC) {
                sock = SOCKET_I(inode);
                ssp = sock->sk->sk_security;
                tsp = current_security();
                /*
                 * If the receiving process can't write to the
                 * passed socket or if the passed socket can't
                 * write to the receiving process don't accept
                 * the passed socket.
                 */
                rc = smk_access(tsp->smk_task, ssp->smk_out, MAY_WRITE, &ad);
                rc = smk_bu_file(file, may, rc);
                if (rc < 0)
                        return rc;
                rc = smk_access(ssp->smk_in, tsp->smk_task, MAY_WRITE, &ad);
                rc = smk_bu_file(file, may, rc);
                return rc;
        }
        /*
         * This code relies on bitmasks.
         */
        if (file->f_mode & FMODE_READ)
                may = MAY_READ;
        if (file->f_mode & FMODE_WRITE)
                may |= MAY_WRITE;

        rc = smk_curacc(smk_of_inode(inode), may, &ad);
        rc = smk_bu_file(file, may, rc);
        return rc;
}

/**
 * smack_file_open - Smack dentry open processing
 * @file: the object
 * @cred: task credential
 *
 * Set the security blob in the file structure.
 * Allow the open only if the task has read access. There are
 * many read operations (e.g. fstat) that you can do with an
 * fd even if you have the file open write-only.
 *
 * Returns 0
 */
static int smack_file_open(struct file *file)
{
        struct task_smack *tsp = file->f_cred->security;
        struct inode *inode = file_inode(file);
        struct smk_audit_info ad;
        int rc;

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
        smk_ad_setfield_u_fs_path(&ad, file->f_path);
        rc = smk_tskacc(tsp, smk_of_inode(inode), MAY_READ, &ad);
        rc = smk_bu_credfile(file->f_cred, file, MAY_READ, rc);

        return rc;
}

/*
 * Task hooks
 */

/**
 * smack_cred_alloc_blank - "allocate" blank task-level security credentials
 * @new: the new credentials
 * @gfp: the atomicity of any memory allocations
 *
 * Prepare a blank set of credentials for modification.  This must allocate all
 * the memory the LSM module might require such that cred_transfer() can
 * complete without error.
 */
static int smack_cred_alloc_blank(struct cred *cred, gfp_t gfp)
{
        struct task_smack *tsp;

        tsp = new_task_smack(NULL, NULL, gfp);
        if (tsp == NULL)
                return -ENOMEM;

        cred->security = tsp;

        return 0;
}


/**
 * smack_cred_free - "free" task-level security credentials
 * @cred: the credentials in question
 *
 */
static void smack_cred_free(struct cred *cred)
{
        struct task_smack *tsp = cred->security;
        struct smack_rule *rp;
        struct list_head *l;
        struct list_head *n;

        if (tsp == NULL)
                return;
        cred->security = NULL;

        smk_destroy_label_list(&tsp->smk_relabel);

        list_for_each_safe(l, n, &tsp->smk_rules) {
                rp = list_entry(l, struct smack_rule, list);
                list_del(&rp->list);
                kfree(rp);
        }
        kfree(tsp);
}

/**
 * smack_cred_prepare - prepare new set of credentials for modification

 * @new: the new credentials
 * @old: the original credentials
 * @gfp: the atomicity of any memory allocations
 *
 * Prepare a new set of credentials for modification.
 */
static int smack_cred_prepare(struct cred *new, const struct cred *old,
                              gfp_t gfp)
{
        struct task_smack *old_tsp = old->security;
        struct task_smack *new_tsp;
        int rc;

        new_tsp = new_task_smack(old_tsp->smk_task, old_tsp->smk_task, gfp);
        if (new_tsp == NULL)
                return -ENOMEM;

        new->security = new_tsp;

        rc = smk_copy_rules(&new_tsp->smk_rules, &old_tsp->smk_rules, gfp);
        if (rc != 0)
                return rc;

        rc = smk_copy_relabel(&new_tsp->smk_relabel, &old_tsp->smk_relabel,
                                gfp);
        if (rc != 0)
                return rc;

        return 0;
}

/**
 * smack_cred_transfer - Transfer the old credentials to the new credentials
 * @new: the new credentials
 * @old: the original credentials
 *
 * Fill in a set of blank credentials from another set of credentials.
 */
static void smack_cred_transfer(struct cred *new, const struct cred *old)
{
        struct task_smack *old_tsp = old->security;
        struct task_smack *new_tsp = new->security;

        new_tsp->smk_task = old_tsp->smk_task;
        new_tsp->smk_forked = old_tsp->smk_task;
        mutex_init(&new_tsp->smk_rules_lock);
        INIT_LIST_HEAD(&new_tsp->smk_rules);


        /* cbs copy rule list */
}

/**
 * smack_cred_getsecid - get the secid corresponding to a creds structure
 * @c: the object creds
 * @secid: where to put the result
 *
 * Sets the secid to contain a u32 version of the smack label.
 */
static void smack_cred_getsecid(const struct cred *c, u32 *secid)
{
        struct smack_known *skp;

        rcu_read_lock();
        skp = smk_of_task(c->security);
        *secid = skp->smk_secid;
        rcu_read_unlock();
}

/**
 * smack_kernel_act_as - Set the subjective context in a set of credentials
 * @new: points to the set of credentials to be modified.
 * @secid: specifies the security ID to be set
 *
 * Set the security data for a kernel service.
 */
static int smack_kernel_act_as(struct cred *new, u32 secid)
{
        struct task_smack *new_tsp = new->security;

        new_tsp->smk_task = smack_from_secid(secid);
        return 0;
}

/**
 * smack_kernel_create_files_as - Set the file creation label in a set of creds
 * @new: points to the set of credentials to be modified
 * @inode: points to the inode to use as a reference
 *
 * Set the file creation context in a set of credentials to the same
 * as the objective context of the specified inode
 */
static int smack_kernel_create_files_as(struct cred *new,
                                        struct inode *inode)
{
        struct inode_smack *isp = inode->i_security;
        struct task_smack *tsp = new->security;

        tsp->smk_forked = isp->smk_inode;
        tsp->smk_task = tsp->smk_forked;
        return 0;
}

/**
 * smk_curacc_on_task - helper to log task related access
 * @p: the task object
 * @access: the access requested
 * @caller: name of the calling function for audit
 *
 * Return 0 if access is permitted
 */
static int smk_curacc_on_task(struct task_struct *p, int access,
                                const char *caller)
{
        struct smk_audit_info ad;
        struct smack_known *skp = smk_of_task_struct(p);
        int rc;

        smk_ad_init(&ad, caller, LSM_AUDIT_DATA_TASK);
        smk_ad_setfield_u_tsk(&ad, p);
        rc = smk_curacc(skp, access, &ad);
        rc = smk_bu_task(p, access, rc);
        return rc;
}

/**
 * smack_task_setpgid - Smack check on setting pgid
 * @p: the task object
 * @pgid: unused
 *
 * Return 0 if write access is permitted
 */
static int smack_task_setpgid(struct task_struct *p, pid_t pgid)
{
        return smk_curacc_on_task(p, MAY_WRITE, __func__);
}

/**
 * smack_task_getpgid - Smack access check for getpgid
 * @p: the object task
 *
 * Returns 0 if current can read the object task, error code otherwise
 */
static int smack_task_getpgid(struct task_struct *p)
{
        return smk_curacc_on_task(p, MAY_READ, __func__);
}

/**
 * smack_task_getsid - Smack access check for getsid
 * @p: the object task
 *
 * Returns 0 if current can read the object task, error code otherwise
 */
static int smack_task_getsid(struct task_struct *p)
{
        return smk_curacc_on_task(p, MAY_READ, __func__);
}

/**
 * smack_task_getsecid - get the secid of the task
 * @p: the object task
 * @secid: where to put the result
 *
 * Sets the secid to contain a u32 version of the smack label.
 */
static void smack_task_getsecid(struct task_struct *p, u32 *secid)
{
        struct smack_known *skp = smk_of_task_struct(p);

        *secid = skp->smk_secid;
}

/**
 * smack_task_setnice - Smack check on setting nice
 * @p: the task object
 * @nice: unused
 *
 * Return 0 if write access is permitted
 */
static int smack_task_setnice(struct task_struct *p, int nice)
{
        return smk_curacc_on_task(p, MAY_WRITE, __func__);
}

/**
 * smack_task_setioprio - Smack check on setting ioprio
 * @p: the task object
 * @ioprio: unused
 *
 * Return 0 if write access is permitted
 */
static int smack_task_setioprio(struct task_struct *p, int ioprio)
{
        return smk_curacc_on_task(p, MAY_WRITE, __func__);
}

/**
 * smack_task_getioprio - Smack check on reading ioprio
 * @p: the task object
 *
 * Return 0 if read access is permitted
 */
static int smack_task_getioprio(struct task_struct *p)
{
        return smk_curacc_on_task(p, MAY_READ, __func__);
}

/**
 * smack_task_setscheduler - Smack check on setting scheduler
 * @p: the task object
 * @policy: unused
 * @lp: unused
 *
 * Return 0 if read access is permitted
 */
static int smack_task_setscheduler(struct task_struct *p)
{
        return smk_curacc_on_task(p, MAY_WRITE, __func__);
}

/**
 * smack_task_getscheduler - Smack check on reading scheduler
 * @p: the task object
 *
 * Return 0 if read access is permitted
 */
static int smack_task_getscheduler(struct task_struct *p)
{
        return smk_curacc_on_task(p, MAY_READ, __func__);
}

/**
 * smack_task_movememory - Smack check on moving memory
 * @p: the task object
 *
 * Return 0 if write access is permitted
 */
static int smack_task_movememory(struct task_struct *p)
{
        return smk_curacc_on_task(p, MAY_WRITE, __func__);
}

/**
 * smack_task_kill - Smack check on signal delivery
 * @p: the task object
 * @info: unused
 * @sig: unused
 * @cred: identifies the cred to use in lieu of current's
 *
 * Return 0 if write access is permitted
 *
 */
static int smack_task_kill(struct task_struct *p, struct siginfo *info,
                           int sig, const struct cred *cred)
{
        struct smk_audit_info ad;
        struct smack_known *skp;
        struct smack_known *tkp = smk_of_task_struct(p);
        int rc;

        if (!sig)
                return 0; /* null signal; existence test */

        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
        smk_ad_setfield_u_tsk(&ad, p);
        /*
         * Sending a signal requires that the sender
         * can write the receiver.
         */
        if (cred == NULL) {
                rc = smk_curacc(tkp, MAY_DELIVER, &ad);
                rc = smk_bu_task(p, MAY_DELIVER, rc);
                return rc;
        }
        /*
         * If the cred isn't NULL we're dealing with some USB IO
         * specific behavior. This is not clean. For one thing
         * we can't take privilege into account.
         */
        skp = smk_of_task(cred->security);
        rc = smk_access(skp, tkp, MAY_DELIVER, &ad);
        rc = smk_bu_note("USB signal", skp, tkp, MAY_DELIVER, rc);
        return rc;
}

/**
 * smack_task_to_inode - copy task smack into the inode blob
 * @p: task to copy from
 * @inode: inode to copy to
 *
 * Sets the smack pointer in the inode security blob
 */
static void smack_task_to_inode(struct task_struct *p, struct inode *inode)
{
        struct inode_smack *isp = inode->i_security;
        struct smack_known *skp = smk_of_task_struct(p);

        isp->smk_inode = skp;
        isp->smk_flags |= SMK_INODE_INSTANT;
}

/*
 * Socket hooks.
 */

/**
 * smack_sk_alloc_security - Allocate a socket blob
 * @sk: the socket
 * @family: unused
 * @gfp_flags: memory allocation flags
 *
 * Assign Smack pointers to current
 *
 * Returns 0 on success, -ENOMEM is there's no memory
 */
static int smack_sk_alloc_security(struct sock *sk, int family, gfp_t gfp_flags)
{
        struct smack_known *skp = smk_of_current();
        struct socket_smack *ssp;

        ssp = kzalloc(sizeof(struct socket_smack), gfp_flags);
        if (ssp == NULL)
                return -ENOMEM;

        /*
         * Sockets created by kernel threads receive web label.
         */
        if (unlikely(current->flags & PF_KTHREAD)) {
                ssp->smk_in = &smack_known_web;
                ssp->smk_out = &smack_known_web;
        } else {
                ssp->smk_in = skp;
                ssp->smk_out = skp;
        }
        ssp->smk_packet = NULL;

        sk->sk_security = ssp;

        return 0;
}

/**
 * smack_sk_free_security - Free a socket blob
 * @sk: the socket
 *
 * Clears the blob pointer
 */
static void smack_sk_free_security(struct sock *sk)
{
#ifdef SMACK_IPV6_PORT_LABELING
        struct smk_port_label *spp;

        if (sk->sk_family == PF_INET6) {
                rcu_read_lock();
                list_for_each_entry_rcu(spp, &smk_ipv6_port_list, list) {
                        if (spp->smk_sock != sk)
                                continue;
                        spp->smk_can_reuse = 1;
                        break;
                }
                rcu_read_unlock();
        }
#endif
        kfree(sk->sk_security);
}

/**
* smack_ipv4host_label - check host based restrictions
* @sip: the object end
*
* looks for host based access restrictions
*
* This version will only be appropriate for really small sets of single label
* hosts.  The caller is responsible for ensuring that the RCU read lock is
* taken before calling this function.
*
* Returns the label of the far end or NULL if it's not special.
*/
static struct smack_known *smack_ipv4host_label(struct sockaddr_in *sip)
{
        struct smk_net4addr *snp;
        struct in_addr *siap = &sip->sin_addr;

        if (siap->s_addr == 0)
                return NULL;

        list_for_each_entry_rcu(snp, &smk_net4addr_list, list)
                /*
                 * we break after finding the first match because
                 * the list is sorted from longest to shortest mask
                 * so we have found the most specific match
                 */
                if (snp->smk_host.s_addr ==
                    (siap->s_addr & snp->smk_mask.s_addr))
                        return snp->smk_label;

        return NULL;
}

#if IS_ENABLED(CONFIG_IPV6)
/*
 * smk_ipv6_localhost - Check for local ipv6 host address
 * @sip: the address
 *
 * Returns boolean true if this is the localhost address
 */
static bool smk_ipv6_localhost(struct sockaddr_in6 *sip)
{
        __be16 *be16p = (__be16 *)&sip->sin6_addr;
        __be32 *be32p = (__be32 *)&sip->sin6_addr;

        if (be32p[0] == 0 && be32p[1] == 0 && be32p[2] == 0 && be16p[6] == 0 &&
            ntohs(be16p[7]) == 1)
                return true;
        return false;
}

/**
* smack_ipv6host_label - check host based restrictions
* @sip: the object end
*
* looks for host based access restrictions
*
* This version will only be appropriate for really small sets of single label
* hosts.  The caller is responsible for ensuring that the RCU read lock is
* taken before calling this function.
*
* Returns the label of the far end or NULL if it's not special.
*/
static struct smack_known *smack_ipv6host_label(struct sockaddr_in6 *sip)
{
        struct smk_net6addr *snp;
        struct in6_addr *sap = &sip->sin6_addr;
        int i;
        int found = 0;

        /*
         * It's local. Don't look for a host label.
         */
        if (smk_ipv6_localhost(sip))
                return NULL;

        list_for_each_entry_rcu(snp, &smk_net6addr_list, list) {
                /*
                 * If the label is NULL the entry has
                 * been renounced. Ignore it.
                 */
                if (snp->smk_label == NULL)
                        continue;
                /*
                * we break after finding the first match because
                * the list is sorted from longest to shortest mask
                * so we have found the most specific match
                */
                for (found = 1, i = 0; i < 8; i++) {
                        if ((sap->s6_addr16[i] & snp->smk_mask.s6_addr16[i]) !=
                            snp->smk_host.s6_addr16[i]) {
                                found = 0;
                                break;
                        }
                }
                if (found)
                        return snp->smk_label;
        }

        return NULL;
}
#endif /* CONFIG_IPV6 */

/**
 * smack_netlabel - Set the secattr on a socket
 * @sk: the socket
 * @labeled: socket label scheme
 *
 * Convert the outbound smack value (smk_out) to a
 * secattr and attach it to the socket.
 *
 * Returns 0 on success or an error code
 */
static int smack_netlabel(struct sock *sk, int labeled)
{
        struct smack_known *skp;
        struct socket_smack *ssp = sk->sk_security;
        int rc = 0;

        /*
         * Usually the netlabel code will handle changing the
         * packet labeling based on the label.
         * The case of a single label host is different, because
         * a single label host should never get a labeled packet
         * even though the label is usually associated with a packet
         * label.
         */
        local_bh_disable();
        bh_lock_sock_nested(sk);

        if (ssp->smk_out == smack_net_ambient ||
            labeled == SMACK_UNLABELED_SOCKET)
                netlbl_sock_delattr(sk);
        else {
                skp = ssp->smk_out;
                rc = netlbl_sock_setattr(sk, sk->sk_family, &skp->smk_netlabel);
        }

        bh_unlock_sock(sk);
        local_bh_enable();

        return rc;
}

/**
 * smack_netlbel_send - Set the secattr on a socket and perform access checks
 * @sk: the socket
 * @sap: the destination address
 *
 * Set the correct secattr for the given socket based on the destination
 * address and perform any outbound access checks needed.
 *
 * Returns 0 on success or an error code.
 *
 */
static int smack_netlabel_send(struct sock *sk, struct sockaddr_in *sap)
{
        struct smack_known *skp;
        int rc;
        int sk_lbl;
        struct smack_known *hkp;
        struct socket_smack *ssp = sk->sk_security;
        struct smk_audit_info ad;

        rcu_read_lock();
        hkp = smack_ipv4host_label(sap);
        if (hkp != NULL) {
#ifdef CONFIG_AUDIT
                struct lsm_network_audit net;

                smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
                ad.a.u.net->family = sap->sin_family;
                ad.a.u.net->dport = sap->sin_port;
                ad.a.u.net->v4info.daddr = sap->sin_addr.s_addr;
#endif
                sk_lbl = SMACK_UNLABELED_SOCKET;
                skp = ssp->smk_out;
                rc = smk_access(skp, hkp, MAY_WRITE, &ad);
                rc = smk_bu_note("IPv4 host check", skp, hkp, MAY_WRITE, rc);
        } else {
                sk_lbl = SMACK_CIPSO_SOCKET;
                rc = 0;
        }
        rcu_read_unlock();
        if (rc != 0)
                return rc;

        return smack_netlabel(sk, sk_lbl);
}

#if IS_ENABLED(CONFIG_IPV6)
/**
 * smk_ipv6_check - check Smack access
 * @subject: subject Smack label
 * @object: object Smack label
 * @address: address
 * @act: the action being taken
 *
 * Check an IPv6 access
 */
static int smk_ipv6_check(struct smack_known *subject,
                                struct smack_known *object,
                                struct sockaddr_in6 *address, int act)
{
#ifdef CONFIG_AUDIT
        struct lsm_network_audit net;
#endif
        struct smk_audit_info ad;
        int rc;

#ifdef CONFIG_AUDIT
        smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
        ad.a.u.net->family = PF_INET6;
        ad.a.u.net->dport = ntohs(address->sin6_port);
        if (act == SMK_RECEIVING)
                ad.a.u.net->v6info.saddr = address->sin6_addr;
        else
                ad.a.u.net->v6info.daddr = address->sin6_addr;
#endif
        rc = smk_access(subject, object, MAY_WRITE, &ad);
        rc = smk_bu_note("IPv6 check", subject, object, MAY_WRITE, rc);
        return rc;
}
#endif /* CONFIG_IPV6 */

#ifdef SMACK_IPV6_PORT_LABELING
/**
 * smk_ipv6_port_label - Smack port access table management
 * @sock: socket
 * @address: address
 *
 * Create or update the port list entry
 */
static void smk_ipv6_port_label(struct socket *sock, struct sockaddr *address)
{
        struct sock *sk = sock->sk;
        struct sockaddr_in6 *addr6;
        struct socket_smack *ssp = sock->sk->sk_security;
        struct smk_port_label *spp;
        unsigned short port = 0;

        if (address == NULL) {
                /*
                 * This operation is changing the Smack information
                 * on the bound socket. Take the changes to the port
                 * as well.
                 */
                rcu_read_lock();
                list_for_each_entry_rcu(spp, &smk_ipv6_port_list, list) {
                        if (sk != spp->smk_sock)
                                continue;
                        spp->smk_in = ssp->smk_in;
                        spp->smk_out = ssp->smk_out;
                        rcu_read_unlock();
                        return;
                }
                /*
                 * A NULL address is only used for updating existing
                 * bound entries. If there isn't one, it's OK.
                 */
                rcu_read_unlock();
                return;
        }

        addr6 = (struct sockaddr_in6 *)address;
        port = ntohs(addr6->sin6_port);
        /*
         * This is a special case that is safely ignored.
         */
        if (port == 0)
                return;

        /*
         * Look for an existing port list entry.
         * This is an indication that a port is getting reused.
         */
        rcu_read_lock();
        list_for_each_entry_rcu(spp, &smk_ipv6_port_list, list) {
                if (spp->smk_port != port || spp->smk_sock_type != sock->type)
                        continue;
                if (spp->smk_can_reuse != 1) {
                        rcu_read_unlock();
                        return;
                }
                spp->smk_port = port;
                spp->smk_sock = sk;
                spp->smk_in = ssp->smk_in;
                spp->smk_out = ssp->smk_out;
                spp->smk_can_reuse = 0;
                rcu_read_unlock();
                return;
        }
        rcu_read_unlock();
        /*
         * A new port entry is required.
         */
        spp = kzalloc(sizeof(*spp), GFP_KERNEL);
        if (spp == NULL)
                return;

        spp->smk_port = port;
        spp->smk_sock = sk;
        spp->smk_in = ssp->smk_in;
        spp->smk_out = ssp->smk_out;
        spp->smk_sock_type = sock->type;
        spp->smk_can_reuse = 0;

        mutex_lock(&smack_ipv6_lock);
        list_add_rcu(&spp->list, &smk_ipv6_port_list);
        mutex_unlock(&smack_ipv6_lock);
        return;
}

/**
 * smk_ipv6_port_check - check Smack port access
 * @sock: socket
 * @address: address
 *
 * Create or update the port list entry
 */
static int smk_ipv6_port_check(struct sock *sk, struct sockaddr_in6 *address,
                                int act)
{
        struct smk_port_label *spp;
        struct socket_smack *ssp = sk->sk_security;
        struct smack_known *skp = NULL;
        unsigned short port;
        struct smack_known *object;

        if (act == SMK_RECEIVING) {
                skp = smack_ipv6host_label(address);
                object = ssp->smk_in;
        } else {
                skp = ssp->smk_out;
                object = smack_ipv6host_label(address);
        }

        /*
         * The other end is a single label host.
         */
        if (skp != NULL && object != NULL)
                return smk_ipv6_check(skp, object, address, act);
        if (skp == NULL)
                skp = smack_net_ambient;
        if (object == NULL)
                object = smack_net_ambient;

        /*
         * It's remote, so port lookup does no good.
         */
        if (!smk_ipv6_localhost(address))
                return smk_ipv6_check(skp, object, address, act);

        /*
         * It's local so the send check has to have passed.
         */
        if (act == SMK_RECEIVING)
                return 0;

        port = ntohs(address->sin6_port);
        rcu_read_lock();
        list_for_each_entry_rcu(spp, &smk_ipv6_port_list, list) {
                if (spp->smk_port != port || spp->smk_sock_type != sk->sk_type)
                        continue;
                object = spp->smk_in;
                if (act == SMK_CONNECTING)
                        ssp->smk_packet = spp->smk_out;
                break;
        }
        rcu_read_unlock();

        return smk_ipv6_check(skp, object, address, act);
}
#endif /* SMACK_IPV6_PORT_LABELING */

/**
 * smack_inode_setsecurity - set smack xattrs
 * @inode: the object
 * @name: attribute name
 * @value: attribute value
 * @size: size of the attribute
 * @flags: unused
 *
 * Sets the named attribute in the appropriate blob
 *
 * Returns 0 on success, or an error code
 */
static int smack_inode_setsecurity(struct inode *inode, const char *name,
                                   const void *value, size_t size, int flags)
{
        struct smack_known *skp;
        struct inode_smack *nsp = inode->i_security;
        struct socket_smack *ssp;
        struct socket *sock;
        int rc = 0;

        if (value == NULL || size > SMK_LONGLABEL || size == 0)
                return -EINVAL;

        skp = smk_import_entry(value, size);
        if (IS_ERR(skp))
                return PTR_ERR(skp);

        if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) {
                nsp->smk_inode = skp;
                nsp->smk_flags |= SMK_INODE_INSTANT;
                return 0;
        }
        /*
         * The rest of the Smack xattrs are only on sockets.
         */
        if (inode->i_sb->s_magic != SOCKFS_MAGIC)
                return -EOPNOTSUPP;

        sock = SOCKET_I(inode);
        if (sock == NULL || sock->sk == NULL)
                return -EOPNOTSUPP;

        ssp = sock->sk->sk_security;

        if (strcmp(name, XATTR_SMACK_IPIN) == 0)
                ssp->smk_in = skp;
        else if (strcmp(name, XATTR_SMACK_IPOUT) == 0) {
                ssp->smk_out = skp;
                if (sock->sk->sk_family == PF_INET) {
                        rc = smack_netlabel(sock->sk, SMACK_CIPSO_SOCKET);
                        if (rc != 0)
                                printk(KERN_WARNING
                                        "Smack: \"%s\" netlbl error %d.\n",
                                        __func__, -rc);
                }
        } else
                return -EOPNOTSUPP;

#ifdef SMACK_IPV6_PORT_LABELING
        if (sock->sk->sk_family == PF_INET6)
                smk_ipv6_port_label(sock, NULL);
#endif

        return 0;
}

/**
 * smack_socket_post_create - finish socket setup
 * @sock: the socket
 * @family: protocol family
 * @type: unused
 * @protocol: unused
 * @kern: unused
 *
 * Sets the netlabel information on the socket
 *
 * Returns 0 on success, and error code otherwise
 */
static int smack_socket_post_create(struct socket *sock, int family,
                                    int type, int protocol, int kern)
{
        struct socket_smack *ssp;

        if (sock->sk == NULL)
                return 0;

        /*
         * Sockets created by kernel threads receive web label.
         */
        if (unlikely(current->flags & PF_KTHREAD)) {
                ssp = sock->sk->sk_security;
                ssp->smk_in = &smack_known_web;
                ssp->smk_out = &smack_known_web;
        }

        if (family != PF_INET)
                return 0;
        /*
         * Set the outbound netlbl.
         */
        return smack_netlabel(sock->sk, SMACK_CIPSO_SOCKET);
}

/**
 * smack_socket_socketpair - create socket pair
 * @socka: one socket
 * @sockb: another socket
 *
 * Cross reference the peer labels for SO_PEERSEC
 *
 * Returns 0 on success, and error code otherwise
 */
static int smack_socket_socketpair(struct socket *socka,
                                   struct socket *sockb)
{
        struct socket_smack *asp = socka->sk->sk_security;
        struct socket_smack *bsp = sockb->sk->sk_security;

        asp->smk_packet = bsp->smk_out;
        bsp->smk_packet = asp->smk_out;

        return 0;
}

#ifdef SMACK_IPV6_PORT_LABELING
/**
 * smack_socket_bind - record port binding information.
 * @sock: the socket
 * @address: the port address
 * @addrlen: size of the address
 *
 * Records the label bound to a port.
 *
 * Returns 0
 */
static int smack_socket_bind(struct socket *sock, struct sockaddr *address,
                                int addrlen)
{
        if (sock->sk != NULL && sock->sk->sk_family == PF_INET6)
                smk_ipv6_port_label(sock, address);
        return 0;
}
#endif /* SMACK_IPV6_PORT_LABELING */

/**
 * smack_socket_connect - connect access check
 * @sock: the socket
 * @sap: the other end
 * @addrlen: size of sap
 *
 * Verifies that a connection may be possible
 *
 * Returns 0 on success, and error code otherwise
 */
static int smack_socket_connect(struct socket *sock, struct sockaddr *sap,
                                int addrlen)
{
        int rc = 0;
#if IS_ENABLED(CONFIG_IPV6)
        struct sockaddr_in6 *sip = (struct sockaddr_in6 *)sap;
#endif
#ifdef SMACK_IPV6_SECMARK_LABELING
        struct smack_known *rsp;
        struct socket_smack *ssp;
#endif

        if (sock->sk == NULL)
                return 0;

#ifdef SMACK_IPV6_SECMARK_LABELING
        ssp = sock->sk->sk_security;
#endif

        switch (sock->sk->sk_family) {
        case PF_INET:
                if (addrlen < sizeof(struct sockaddr_in))
                        return -EINVAL;
                rc = smack_netlabel_send(sock->sk, (struct sockaddr_in *)sap);
                break;
        case PF_INET6:
                if (addrlen < sizeof(struct sockaddr_in6))
                        return -EINVAL;
#ifdef SMACK_IPV6_SECMARK_LABELING
                rsp = smack_ipv6host_label(sip);
                if (rsp != NULL)
                        rc = smk_ipv6_check(ssp->smk_out, rsp, sip,
                                                SMK_CONNECTING);
#endif
#ifdef SMACK_IPV6_PORT_LABELING
                rc = smk_ipv6_port_check(sock->sk, sip, SMK_CONNECTING);
#endif
                break;
        }
        return rc;
}

/**
 * smack_flags_to_may - convert S_ to MAY_ values
 * @flags: the S_ value
 *
 * Returns the equivalent MAY_ value
 */
static int smack_flags_to_may(int flags)
{
        int may = 0;

        if (flags & S_IRUGO)
                may |= MAY_READ;
        if (flags & S_IWUGO)
                may |= MAY_WRITE;
        if (flags & S_IXUGO)
                may |= MAY_EXEC;

        return may;
}

/**
 * smack_msg_msg_alloc_security - Set the security blob for msg_msg
 * @msg: the object
 *
 * Returns 0
 */
static int smack_msg_msg_alloc_security(struct msg_msg *msg)
{
        struct smack_known *skp = smk_of_current();

        msg->security = skp;
        return 0;
}

/**
 * smack_msg_msg_free_security - Clear the security blob for msg_msg
 * @msg: the object
 *
 * Clears the blob pointer
 */
static void smack_msg_msg_free_security(struct msg_msg *msg)
{
        msg->security = NULL;
}

/**
 * smack_of_ipc - the smack pointer for the ipc
 * @isp: the object
 *
 * Returns a pointer to the smack value
 */
static struct smack_known *smack_of_ipc(struct kern_ipc_perm *isp)
{
        return (struct smack_known *)isp->security;
}

/**
 * smack_ipc_alloc_security - Set the security blob for ipc
 * @isp: the object
 *
 * Returns 0

 */
static int smack_ipc_alloc_security(struct kern_ipc_perm *isp)
{
        struct smack_known *skp = smk_of_current();

        isp->security = skp;
        return 0;
}

/**
 * smack_ipc_free_security - Clear the security blob for ipc
 * @isp: the object
 *
 * Clears the blob pointer
 */
static void smack_ipc_free_security(struct kern_ipc_perm *isp)
{
        isp->security = NULL;
}

/**
 * smk_curacc_shm : check if current has access on shm
 * @isp : the object
 * @access : access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smk_curacc_shm(struct kern_ipc_perm *isp, int access)
{
        struct smack_known *ssp = smack_of_ipc(isp);
        struct smk_audit_info ad;
        int rc;

#ifdef CONFIG_AUDIT
        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_IPC);
        ad.a.u.ipc_id = isp->id;
#endif
        rc = smk_curacc(ssp, access, &ad);
        rc = smk_bu_current("shm", ssp, access, rc);
        return rc;
}

/**
 * smack_shm_associate - Smack access check for shm
 * @isp: the object
 * @shmflg: access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_shm_associate(struct kern_ipc_perm *isp, int shmflg)
{
        int may;

        may = smack_flags_to_may(shmflg);
        return smk_curacc_shm(isp, may);
}

/**
 * smack_shm_shmctl - Smack access check for shm
 * @isp: the object
 * @cmd: what it wants to do
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_shm_shmctl(struct kern_ipc_perm *isp, int cmd)
{
        int may;

        switch (cmd) {
        case IPC_STAT:
        case SHM_STAT:
        case SHM_STAT_ANY:
                may = MAY_READ;
                break;
        case IPC_SET:
        case SHM_LOCK:
        case SHM_UNLOCK:
        case IPC_RMID:
                may = MAY_READWRITE;
                break;
        case IPC_INFO:
        case SHM_INFO:
                /*
                 * System level information.
                 */
                return 0;
        default:
                return -EINVAL;
        }
        return smk_curacc_shm(isp, may);
}

/**
 * smack_shm_shmat - Smack access for shmat
 * @isp: the object
 * @shmaddr: unused
 * @shmflg: access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_shm_shmat(struct kern_ipc_perm *ipc, char __user *shmaddr,
                           int shmflg)
{
        int may;

        may = smack_flags_to_may(shmflg);
        return smk_curacc_shm(ipc, may);
}

/**
 * smk_curacc_sem : check if current has access on sem
 * @isp : the object
 * @access : access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smk_curacc_sem(struct kern_ipc_perm *isp, int access)
{
        struct smack_known *ssp = smack_of_ipc(isp);
        struct smk_audit_info ad;
        int rc;

#ifdef CONFIG_AUDIT
        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_IPC);
        ad.a.u.ipc_id = isp->id;
#endif
        rc = smk_curacc(ssp, access, &ad);
        rc = smk_bu_current("sem", ssp, access, rc);
        return rc;
}

/**
 * smack_sem_associate - Smack access check for sem
 * @isp: the object
 * @semflg: access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_sem_associate(struct kern_ipc_perm *isp, int semflg)
{
        int may;

        may = smack_flags_to_may(semflg);
        return smk_curacc_sem(isp, may);
}

/**
 * smack_sem_shmctl - Smack access check for sem
 * @isp: the object
 * @cmd: what it wants to do
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_sem_semctl(struct kern_ipc_perm *isp, int cmd)
{
        int may;

        switch (cmd) {
        case GETPID:
        case GETNCNT:
        case GETZCNT:
        case GETVAL:
        case GETALL:
        case IPC_STAT:
        case SEM_STAT:
        case SEM_STAT_ANY:
                may = MAY_READ;
                break;
        case SETVAL:
        case SETALL:
        case IPC_RMID:
        case IPC_SET:
                may = MAY_READWRITE;
                break;
        case IPC_INFO:
        case SEM_INFO:
                /*
                 * System level information
                 */
                return 0;
        default:
                return -EINVAL;
        }

        return smk_curacc_sem(isp, may);
}

/**
 * smack_sem_semop - Smack checks of semaphore operations
 * @isp: the object
 * @sops: unused
 * @nsops: unused
 * @alter: unused
 *
 * Treated as read and write in all cases.
 *
 * Returns 0 if access is allowed, error code otherwise
 */
static int smack_sem_semop(struct kern_ipc_perm *isp, struct sembuf *sops,
                           unsigned nsops, int alter)
{
        return smk_curacc_sem(isp, MAY_READWRITE);
}

/**
 * smk_curacc_msq : helper to check if current has access on msq
 * @isp : the msq
 * @access : access requested
 *
 * return 0 if current has access, error otherwise
 */
static int smk_curacc_msq(struct kern_ipc_perm *isp, int access)
{
        struct smack_known *msp = smack_of_ipc(isp);
        struct smk_audit_info ad;
        int rc;

#ifdef CONFIG_AUDIT
        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_IPC);
        ad.a.u.ipc_id = isp->id;
#endif
        rc = smk_curacc(msp, access, &ad);
        rc = smk_bu_current("msq", msp, access, rc);
        return rc;
}

/**
 * smack_msg_queue_associate - Smack access check for msg_queue
 * @isp: the object
 * @msqflg: access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_msg_queue_associate(struct kern_ipc_perm *isp, int msqflg)
{
        int may;

        may = smack_flags_to_may(msqflg);
        return smk_curacc_msq(isp, may);
}

/**
 * smack_msg_queue_msgctl - Smack access check for msg_queue
 * @isp: the object
 * @cmd: what it wants to do
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_msg_queue_msgctl(struct kern_ipc_perm *isp, int cmd)
{
        int may;

        switch (cmd) {
        case IPC_STAT:
        case MSG_STAT:
        case MSG_STAT_ANY:
                may = MAY_READ;
                break;
        case IPC_SET:
        case IPC_RMID:
                may = MAY_READWRITE;
                break;
        case IPC_INFO:
        case MSG_INFO:
                /*
                 * System level information
                 */
                return 0;
        default:
                return -EINVAL;
        }

        return smk_curacc_msq(isp, may);
}

/**
 * smack_msg_queue_msgsnd - Smack access check for msg_queue
 * @isp: the object
 * @msg: unused
 * @msqflg: access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_msg_queue_msgsnd(struct kern_ipc_perm *isp, struct msg_msg *msg,
                                  int msqflg)
{
        int may;

        may = smack_flags_to_may(msqflg);
        return smk_curacc_msq(isp, may);
}

/**
 * smack_msg_queue_msgsnd - Smack access check for msg_queue
 * @isp: the object
 * @msg: unused
 * @target: unused
 * @type: unused
 * @mode: unused
 *
 * Returns 0 if current has read and write access, error code otherwise
 */
static int smack_msg_queue_msgrcv(struct kern_ipc_perm *isp, struct msg_msg *msg,
                        struct task_struct *target, long type, int mode)
{
        return smk_curacc_msq(isp, MAY_READWRITE);
}

/**
 * smack_ipc_permission - Smack access for ipc_permission()
 * @ipp: the object permissions
 * @flag: access requested
 *
 * Returns 0 if current has read and write access, error code otherwise
 */
static int smack_ipc_permission(struct kern_ipc_perm *ipp, short flag)
{
        struct smack_known *iskp = ipp->security;
        int may = smack_flags_to_may(flag);
        struct smk_audit_info ad;
        int rc;

#ifdef CONFIG_AUDIT
        smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_IPC);
        ad.a.u.ipc_id = ipp->id;
#endif
        rc = smk_curacc(iskp, may, &ad);
        rc = smk_bu_current("svipc", iskp, may, rc);
        return rc;
}

/**
 * smack_ipc_getsecid - Extract smack security id
 * @ipp: the object permissions
 * @secid: where result will be saved
 */
static void smack_ipc_getsecid(struct kern_ipc_perm *ipp, u32 *secid)
{
        struct smack_known *iskp = ipp->security;

        *secid = iskp->smk_secid;
}

/**
 * smack_d_instantiate - Make sure the blob is correct on an inode
 * @opt_dentry: dentry where inode will be attached
 * @inode: the object
 *
 * Set the inode's security blob if it hasn't been done already.
 */
static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
{
        struct super_block *sbp;
        struct superblock_smack *sbsp;
        struct inode_smack *isp;
        struct smack_known *skp;
        struct smack_known *ckp = smk_of_current();
        struct smack_known *final;
        char trattr[TRANS_TRUE_SIZE];
        int transflag = 0;
        int rc;
        struct dentry *dp;

        if (inode == NULL)
                return;

        isp = inode->i_security;

        mutex_lock(&isp->smk_lock);
        /*
         * If the inode is already instantiated
         * take the quick way out
         */
        if (isp->smk_flags & SMK_INODE_INSTANT)
                goto unlockandout;

        sbp = inode->i_sb;
        sbsp = sbp->s_security;
        /*
         * We're going to use the superblock default label
         * if there's no label on the file.
         */
        final = sbsp->smk_default;

        /*
         * If this is the root inode the superblock
         * may be in the process of initialization.
         * If that is the case use the root value out
         * of the superblock.
         */
        if (opt_dentry->d_parent == opt_dentry) {
                switch (sbp->s_magic) {
                case CGROUP_SUPER_MAGIC:
                case CGROUP2_SUPER_MAGIC:
                        /*
                         * The cgroup filesystem is never mounted,
                         * so there's no opportunity to set the mount
                         * options.
                         */
                        sbsp->smk_root = &smack_known_star;
                        sbsp->smk_default = &smack_known_star;
                        isp->smk_inode = sbsp->smk_root;
                        break;
                case TMPFS_MAGIC:
                        /*
                         * What about shmem/tmpfs anonymous files with dentry
                         * obtained from d_alloc_pseudo()?
                         */
                        isp->smk_inode = smk_of_current();
                        break;
                case PIPEFS_MAGIC:
                        isp->smk_inode = smk_of_current();
                        break;
                case SOCKFS_MAGIC:
                        /*
                         * Socket access is controlled by the socket
                         * structures associated with the task involved.
                         */
                        isp->smk_inode = &smack_known_star;
                        break;
                default:
                        isp->smk_inode = sbsp->smk_root;
                        break;
                }
                isp->smk_flags |= SMK_INODE_INSTANT;
                goto unlockandout;
        }

        /*
         * This is pretty hackish.
         * Casey says that we shouldn't have to do
         * file system specific code, but it does help
         * with keeping it simple.
         */
        switch (sbp->s_magic) {
        case SMACK_MAGIC:
        case CGROUP_SUPER_MAGIC:
        case CGROUP2_SUPER_MAGIC:
                /*
                 * Casey says that it's a little embarrassing
                 * that the smack file system doesn't do
                 * extended attributes.
                 *
                 * Cgroupfs is special
                 */
                final = &smack_known_star;
                break;
        case DEVPTS_SUPER_MAGIC:
                /*
                 * devpts seems content with the label of the task.
                 * Programs that change smack have to treat the
                 * pty with respect.
                 */
                final = ckp;
                break;
        case PROC_SUPER_MAGIC:
                /*
                 * Casey says procfs appears not to care.
                 * The superblock default suffices.
                 */
                break;
        case TMPFS_MAGIC:
                /*
                 * Device labels should come from the filesystem,
                 * but watch out, because they're volitile,
                 * getting recreated on every reboot.
                 */
                final = &smack_known_star;
                /*
                 * No break.
                 *
                 * If a smack value has been set we want to use it,
                 * but since tmpfs isn't giving us the opportunity
                 * to set mount options simulate setting the
                 * superblock default.
                 */
        default:
                /*
                 * This isn't an understood special case.
                 * Get the value from the xattr.
                 */

                /*
                 * UNIX domain sockets use lower level socket data.
                 */
                if (S_ISSOCK(inode->i_mode)) {
                        final = &smack_known_star;
                        break;
                }
                /*
                 * No xattr support means, alas, no SMACK label.
                 * Use the aforeapplied default.
                 * It would be curious if the label of the task
                 * does not match that assigned.
                 */
                if (!(inode->i_opflags & IOP_XATTR))
                        break;
                /*
                 * Get the dentry for xattr.
                 */
                dp = dget(opt_dentry);
                skp = smk_fetch(XATTR_NAME_SMACK, inode, dp);
                if (!IS_ERR_OR_NULL(skp))
                        final = skp;

                /*
                 * Transmuting directory
                 */
                if (S_ISDIR(inode->i_mode)) {
                        /*
                         * If this is a new directory and the label was
                         * transmuted when the inode was initialized
                         * set the transmute attribute on the directory
                         * and mark the inode.
                         *
                         * If there is a transmute attribute on the
                         * directory mark the inode.
                         */
                        if (isp->smk_flags & SMK_INODE_CHANGED) {
                                isp->smk_flags &= ~SMK_INODE_CHANGED;
                                rc = __vfs_setxattr(dp, inode,
                                        XATTR_NAME_SMACKTRANSMUTE,
                                        TRANS_TRUE, TRANS_TRUE_SIZE,
                                        0);
                        } else {
                                rc = __vfs_getxattr(dp, inode,
                                        XATTR_NAME_SMACKTRANSMUTE, trattr,
                                        TRANS_TRUE_SIZE);
                                if (rc >= 0 && strncmp(trattr, TRANS_TRUE,
                                                       TRANS_TRUE_SIZE) != 0)
                                        rc = -EINVAL;
                        }
                        if (rc >= 0)
                                transflag = SMK_INODE_TRANSMUTE;
                }
                /*
                 * Don't let the exec or mmap label be "*" or "@".
                 */
                skp = smk_fetch(XATTR_NAME_SMACKEXEC, inode, dp);
                if (IS_ERR(skp) || skp == &smack_known_star ||
                    skp == &smack_known_web)
                        skp = NULL;
                isp->smk_task = skp;

                skp = smk_fetch(XATTR_NAME_SMACKMMAP, inode, dp);
                if (IS_ERR(skp) || skp == &smack_known_star ||
                    skp == &smack_known_web)
                        skp = NULL;
                isp->smk_mmap = skp;

                dput(dp);
                break;
        }

        if (final == NULL)
                isp->smk_inode = ckp;
        else
                isp->smk_inode = final;

        isp->smk_flags |= (SMK_INODE_INSTANT | transflag);

unlockandout:
        mutex_unlock(&isp->smk_lock);
        return;
}

/**
 * smack_getprocattr - Smack process attribute access
 * @p: the object task
 * @name: the name of the attribute in /proc/.../attr
 * @value: where to put the result
 *
 * Places a copy of the task Smack into value
 *
 * Returns the length of the smack label or an error code
 */
static int smack_getprocattr(struct task_struct *p, char *name, char **value)
{
        struct smack_known *skp = smk_of_task_struct(p);
        char *cp;
        int slen;

        if (strcmp(name, "current") != 0)
                return -EINVAL;

        cp = kstrdup(skp->smk_known, GFP_KERNEL);
        if (cp == NULL)
                return -ENOMEM;

        slen = strlen(cp);
        *value = cp;
        return slen;
}

/**
 * smack_setprocattr - Smack process attribute setting
 * @name: the name of the attribute in /proc/.../attr
 * @value: the value to set
 * @size: the size of the value
 *
 * Sets the Smack value of the task. Only setting self
 * is permitted and only with privilege
 *
 * Returns the length of the smack label or an error code
 */
static int smack_setprocattr(const char *name, void *value, size_t size)
{
        struct task_smack *tsp = current_security();
        struct cred *new;
        struct smack_known *skp;
        struct smack_known_list_elem *sklep;
        int rc;

        if (!smack_privileged(CAP_MAC_ADMIN) && list_empty(&tsp->smk_relabel))
                return -EPERM;

        if (value == NULL || size == 0 || size >= SMK_LONGLABEL)
                return -EINVAL;

        if (strcmp(name, "current") != 0)
                return -EINVAL;

        skp = smk_import_entry(value, size);
        if (IS_ERR(skp))
                return PTR_ERR(skp);

        /*
         * No process is ever allowed the web ("@") label
         * and the star ("*") label.
         */
        if (skp == &smack_known_web || skp == &smack_known_star)
                return -EINVAL;

        if (!smack_privileged(CAP_MAC_ADMIN)) {
                rc = -EPERM;
                list_for_each_entry(sklep, &tsp->smk_relabel, list)
                        if (sklep->smk_label == skp) {
                                rc = 0;
                                break;
                        }
                if (rc)
                        return rc;
        }

        new = prepare_creds();
        if (new == NULL)
                return -ENOMEM;

        tsp = new->security;
        tsp->smk_task = skp;
        /*
         * process can change its label only once
         */
        smk_destroy_label_list(&tsp->smk_relabel);

        commit_creds(new);
        return size;
}

/**
 * smack_unix_stream_connect - Smack access on UDS
 * @sock: one sock
 * @other: the other sock
 * @newsk: unused
 *
 * Return 0 if a subject with the smack of sock could access
 * an object with the smack of other, otherwise an error code
 */
static int smack_unix_stream_connect(struct sock *sock,
                                     struct sock *other, struct sock *newsk)
{
        struct smack_known *skp;
        struct smack_known *okp;
        struct socket_smack *ssp = sock->sk_security;
        struct socket_smack *osp = other->sk_security;
        struct socket_smack *nsp = newsk->sk_security;
        struct smk_audit_info ad;
        int rc = 0;
#ifdef CONFIG_AUDIT
        struct lsm_network_audit net;
#endif

        if (!smack_privileged(CAP_MAC_OVERRIDE)) {
                skp = ssp->smk_out;
                okp = osp->smk_in;
#ifdef CONFIG_AUDIT
                smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
                smk_ad_setfield_u_net_sk(&ad, other);
#endif
                rc = smk_access(skp, okp, MAY_WRITE, &ad);
                rc = smk_bu_note("UDS connect", skp, okp, MAY_WRITE, rc);
                if (rc == 0) {
                        okp = osp->smk_out;
                        skp = ssp->smk_in;
                        rc = smk_access(okp, skp, MAY_WRITE, &ad);
                        rc = smk_bu_note("UDS connect", okp, skp,
                                                MAY_WRITE, rc);
                }
        }

        /*
         * Cross reference the peer labels for SO_PEERSEC.
         */
        if (rc == 0) {
                nsp->smk_packet = ssp->smk_out;
                ssp->smk_packet = osp->smk_out;
        }

        return rc;
}

/**
 * smack_unix_may_send - Smack access on UDS
 * @sock: one socket
 * @other: the other socket
 *
 * Return 0 if a subject with the smack of sock could access
 * an object with the smack of other, otherwise an error code
 */
static int smack_unix_may_send(struct socket *sock, struct socket *other)
{
        struct socket_smack *ssp = sock->sk->sk_security;
        struct socket_smack *osp = other->sk->sk_security;
        struct smk_audit_info ad;
        int rc;

#ifdef CONFIG_AUDIT
        struct lsm_network_audit net;

        smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
        smk_ad_setfield_u_net_sk(&ad, other->sk);
#endif

        if (smack_privileged(CAP_MAC_OVERRIDE))
                return 0;

        rc = smk_access(ssp->smk_out, osp->smk_in, MAY_WRITE, &ad);
        rc = smk_bu_note("UDS send", ssp->smk_out, osp->smk_in, MAY_WRITE, rc);
        return rc;
}

/**
 * smack_socket_sendmsg - Smack check based on destination host
 * @sock: the socket
 * @msg: the message
 * @size: the size of the message
 *
 * Return 0 if the current subject can write to the destination host.
 * For IPv4 this is only a question if the destination is a single label host.
 * For IPv6 this is a check against the label of the port.
 */
static int smack_socket_sendmsg(struct socket *sock, struct msghdr *msg,
                                int size)
{
        struct sockaddr_in *sip = (struct sockaddr_in *) msg->msg_name;
#if IS_ENABLED(CONFIG_IPV6)
        struct sockaddr_in6 *sap = (struct sockaddr_in6 *) msg->msg_name;
#endif
#ifdef SMACK_IPV6_SECMARK_LABELING
        struct socket_smack *ssp = sock->sk->sk_security;
        struct smack_known *rsp;
#endif
        int rc = 0;

        /*
         * Perfectly reasonable for this to be NULL
         */
        if (sip == NULL)
                return 0;

        switch (sock->sk->sk_family) {
        case AF_INET:
                rc = smack_netlabel_send(sock->sk, sip);
                break;
        case AF_INET6:
#ifdef SMACK_IPV6_SECMARK_LABELING
                rsp = smack_ipv6host_label(sap);
                if (rsp != NULL)
                        rc = smk_ipv6_check(ssp->smk_out, rsp, sap,
                                                SMK_CONNECTING);
#endif
#ifdef SMACK_IPV6_PORT_LABELING
                rc = smk_ipv6_port_check(sock->sk, sap, SMK_SENDING);
#endif
                break;
        }
        return rc;
}

/**
 * smack_from_secattr - Convert a netlabel attr.mls.lvl/attr.mls.cat pair to smack
 * @sap: netlabel secattr
 * @ssp: socket security information
 *
 * Returns a pointer to a Smack label entry found on the label list.
 */
static struct smack_known *smack_from_secattr(struct netlbl_lsm_secattr *sap,
                                                struct socket_smack *ssp)
{
        struct smack_known *skp;
        int found = 0;
        int acat;
        int kcat;

        if ((sap->flags & NETLBL_SECATTR_MLS_LVL) != 0) {
                /*
                 * Looks like a CIPSO packet.
                 * If there are flags but no level netlabel isn't
                 * behaving the way we expect it to.
                 *
                 * Look it up in the label table
                 * Without guidance regarding the smack value
                 * for the packet fall back on the network
                 * ambient value.
                 */
                rcu_read_lock();
                list_for_each_entry_rcu(skp, &smack_known_list, list) {
                        if (sap->attr.mls.lvl != skp->smk_netlabel.attr.mls.lvl)
                                continue;
                        /*
                         * Compare the catsets. Use the netlbl APIs.
                         */
                        if ((sap->flags & NETLBL_SECATTR_MLS_CAT) == 0) {
                                if ((skp->smk_netlabel.flags &
                                     NETLBL_SECATTR_MLS_CAT) == 0)
                                        found = 1;
                                break;
                        }
                        for (acat = -1, kcat = -1; acat == kcat; ) {
                                acat = netlbl_catmap_walk(sap->attr.mls.cat,
                                                          acat + 1);
                                kcat = netlbl_catmap_walk(
                                        skp->smk_netlabel.attr.mls.cat,
                                        kcat + 1);
                                if (acat < 0 || kcat < 0)
                                        break;
                        }
                        if (acat == kcat) {
                                found = 1;
                                break;
                        }
                }
                rcu_read_unlock();

                if (found)
                        return skp;

                if (ssp != NULL && ssp->smk_in == &smack_known_star)
                        return &smack_known_web;
                return &smack_known_star;
        }
        if ((sap->flags & NETLBL_SECATTR_SECID) != 0)
                /*
                 * Looks like a fallback, which gives us a secid.
                 */
                return smack_from_secid(sap->attr.secid);
        /*
         * Without guidance regarding the smack value
         * for the packet fall back on the network
         * ambient value.
         */
        return smack_net_ambient;
}

#if IS_ENABLED(CONFIG_IPV6)
static int smk_skb_to_addr_ipv6(struct sk_buff *skb, struct sockaddr_in6 *sip)
{
        u8 nexthdr;
        int offset;
        int proto = -EINVAL;
        struct ipv6hdr _ipv6h;
        struct ipv6hdr *ip6;
        __be16 frag_off;
        struct tcphdr _tcph, *th;
        struct udphdr _udph, *uh;
        struct dccp_hdr _dccph, *dh;

        sip->sin6_port = 0;

        offset = skb_network_offset(skb);
        ip6 = skb_header_pointer(skb, offset, sizeof(_ipv6h), &_ipv6h);
        if (ip6 == NULL)
                return -EINVAL;
        sip->sin6_addr = ip6->saddr;

        nexthdr = ip6->nexthdr;
        offset += sizeof(_ipv6h);
        offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
        if (offset < 0)
                return -EINVAL;

        proto = nexthdr;
        switch (proto) {
        case IPPROTO_TCP:
                th = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
                if (th != NULL)
                        sip->sin6_port = th->source;
                break;
        case IPPROTO_UDP:
        case IPPROTO_UDPLITE:
                uh = skb_header_pointer(skb, offset, sizeof(_udph), &_udph);
                if (uh != NULL)
                        sip->sin6_port = uh->source;
                break;
        case IPPROTO_DCCP:
                dh = skb_header_pointer(skb, offset, sizeof(_dccph), &_dccph);
                if (dh != NULL)
                        sip->sin6_port = dh->dccph_sport;
                break;
        }
        return proto;
}
#endif /* CONFIG_IPV6 */

/**
 * smack_socket_sock_rcv_skb - Smack packet delivery access check
 * @sk: socket
 * @skb: packet
 *
 * Returns 0 if the packet should be delivered, an error code otherwise
 */
static int smack_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
        struct netlbl_lsm_secattr secattr;
        struct socket_smack *ssp = sk->sk_security;
        struct smack_known *skp = NULL;
        int rc = 0;
        struct smk_audit_info ad;
        u16 family = sk->sk_family;
#ifdef CONFIG_AUDIT
        struct lsm_network_audit net;
#endif
#if IS_ENABLED(CONFIG_IPV6)
        struct sockaddr_in6 sadd;
        int proto;

        if (family == PF_INET6 && skb->protocol == htons(ETH_P_IP))
                family = PF_INET;
#endif /* CONFIG_IPV6 */

        switch (family) {
        case PF_INET:
#ifdef CONFIG_SECURITY_SMACK_NETFILTER
                /*
                 * If there is a secmark use it rather than the CIPSO label.
                 * If there is no secmark fall back to CIPSO.
                 * The secmark is assumed to reflect policy better.
                 */
                if (skb && skb->secmark != 0) {
                        skp = smack_from_secid(skb->secmark);
                        goto access_check;
                }
#endif /* CONFIG_SECURITY_SMACK_NETFILTER */
                /*
                 * Translate what netlabel gave us.
                 */
                netlbl_secattr_init(&secattr);

                rc = netlbl_skbuff_getattr(skb, family, &secattr);
                if (rc == 0)
                        skp = smack_from_secattr(&secattr, ssp);
                else
                        skp = smack_net_ambient;

                netlbl_secattr_destroy(&secattr);

#ifdef CONFIG_SECURITY_SMACK_NETFILTER
access_check:
#endif
#ifdef CONFIG_AUDIT
                smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
                ad.a.u.net->family = family;
                ad.a.u.net->netif = skb->skb_iif;
                ipv4_skb_to_auditdata(skb, &ad.a, NULL);
#endif
                /*
                 * Receiving a packet requires that the other end
                 * be able to write here. Read access is not required.
                 * This is the simplist possible security model
                 * for networking.
                 */
                rc = smk_access(skp, ssp->smk_in, MAY_WRITE, &ad);
                rc = smk_bu_note("IPv4 delivery", skp, ssp->smk_in,
                                        MAY_WRITE, rc);
                if (rc != 0)
                        netlbl_skbuff_err(skb, family, rc, 0);
                break;
#if IS_ENABLED(CONFIG_IPV6)
        case PF_INET6:
                proto = smk_skb_to_addr_ipv6(skb, &sadd);
                if (proto != IPPROTO_UDP && proto != IPPROTO_UDPLITE &&
                    proto != IPPROTO_TCP && proto != IPPROTO_DCCP)
                        break;
#ifdef SMACK_IPV6_SECMARK_LABELING
                if (skb && skb->secmark != 0)
                        skp = smack_from_secid(skb->secmark);
                else
                        skp = smack_ipv6host_label(&sadd);
                if (skp == NULL)
                        skp = smack_net_ambient;