/*
 * Copyright (C) 2008 IBM Corporation
 * Author: Mimi Zohar <zohar@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 2 of the License.
 *
 * ima_policy.c
 *      - initialize default measure policy rules
 *
 */
#include <linux/module.h>
#include <linux/list.h>
#include <linux/fs.h>
#include <linux/security.h>
#include <linux/magic.h>
#include <linux/parser.h>
#include <linux/slab.h>
#include <linux/rculist.h>
#include <linux/genhd.h>
#include <linux/seq_file.h>

#include "ima.h"

/* flags definitions */
#define IMA_FUNC        0x0001
#define IMA_MASK        0x0002
#define IMA_FSMAGIC     0x0004
#define IMA_UID         0x0008
#define IMA_FOWNER      0x0010
#define IMA_FSUUID      0x0020
#define IMA_INMASK      0x0040
#define IMA_EUID        0x0080
#define IMA_PCR         0x0100

#define UNKNOWN         0
#define MEASURE         0x0001  /* same as IMA_MEASURE */
#define DONT_MEASURE    0x0002
#define APPRAISE        0x0004  /* same as IMA_APPRAISE */
#define DONT_APPRAISE   0x0008
#define AUDIT           0x0040

#define INVALID_PCR(a) (((a) < 0) || \
        (a) >= (FIELD_SIZEOF(struct integrity_iint_cache, measured_pcrs) * 8))

int ima_policy_flag;
static int temp_ima_appraise;

#define MAX_LSM_RULES 6
enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
        LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
};

enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB };

struct ima_rule_entry {
        struct list_head list;
        int action;
        unsigned int flags;
        enum ima_hooks func;
        int mask;
        unsigned long fsmagic;
        u8 fsuuid[16];
        kuid_t uid;
        kuid_t fowner;
        int pcr;
        struct {
                void *rule;     /* LSM file metadata specific */
                void *args_p;   /* audit value */
                int type;       /* audit type */
        } lsm[MAX_LSM_RULES];
};

/*
 * Without LSM specific knowledge, the default policy can only be
 * written in terms of .action, .func, .mask, .fsmagic, .uid, and .fowner
 */

/*
 * The minimum rule set to allow for full TCB coverage.  Measures all files
 * opened or mmap for exec and everything read by root.  Dangerous because
 * normal users can easily run the machine out of memory simply building
 * and running executables.
 */
static struct ima_rule_entry dont_measure_rules[] = {
        {.action = DONT_MEASURE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = CGROUP_SUPER_MAGIC,
         .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC}
};

static struct ima_rule_entry original_measurement_rules[] = {
        {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
         .flags = IMA_FUNC | IMA_MASK},
        {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
         .flags = IMA_FUNC | IMA_MASK},
        {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
         .uid = GLOBAL_ROOT_UID, .flags = IMA_FUNC | IMA_MASK | IMA_UID},
        {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
        {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
};

static struct ima_rule_entry default_measurement_rules[] = {
        {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
         .flags = IMA_FUNC | IMA_MASK},
        {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
         .flags = IMA_FUNC | IMA_MASK},
        {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
         .uid = GLOBAL_ROOT_UID, .flags = IMA_FUNC | IMA_INMASK | IMA_EUID},
        {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
         .uid = GLOBAL_ROOT_UID, .flags = IMA_FUNC | IMA_INMASK | IMA_UID},
        {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
        {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
        {.action = MEASURE, .func = POLICY_CHECK, .flags = IMA_FUNC},
};

static struct ima_rule_entry default_appraise_rules[] = {
        {.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
#ifdef CONFIG_IMA_WRITE_POLICY
        {.action = APPRAISE, .func = POLICY_CHECK,
        .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
#endif
#ifndef CONFIG_IMA_APPRAISE_SIGNED_INIT
        {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .flags = IMA_FOWNER},
#else
        /* force signature */
        {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID,
         .flags = IMA_FOWNER | IMA_DIGSIG_REQUIRED},
#endif
};

static LIST_HEAD(ima_default_rules);
static LIST_HEAD(ima_policy_rules);
static LIST_HEAD(ima_temp_rules);
static struct list_head *ima_rules;

static int ima_policy __initdata;

static int __init default_measure_policy_setup(char *str)
{
        if (ima_policy)
                return 1;

        ima_policy = ORIGINAL_TCB;
        return 1;
}
__setup("ima_tcb", default_measure_policy_setup);

static int __init policy_setup(char *str)
{
        if (ima_policy)
                return 1;

        if (strcmp(str, "tcb") == 0)
                ima_policy = DEFAULT_TCB;

        return 1;
}
__setup("ima_policy=", policy_setup);

static bool ima_use_appraise_tcb __initdata;
static int __init default_appraise_policy_setup(char *str)
{
        ima_use_appraise_tcb = 1;
        return 1;
}
__setup("ima_appraise_tcb", default_appraise_policy_setup);

/*
 * The LSM policy can be reloaded, leaving the IMA LSM based rules referring
 * to the old, stale LSM policy.  Update the IMA LSM based rules to reflect
 * the reloaded LSM policy.  We assume the rules still exist; and BUG_ON() if
 * they don't.
 */
static void ima_lsm_update_rules(void)
{
        struct ima_rule_entry *entry;
        int result;
        int i;

        list_for_each_entry(entry, &ima_policy_rules, list) {
                for (i = 0; i < MAX_LSM_RULES; i++) {
                        if (!entry->lsm[i].rule)
                                continue;
                        result = security_filter_rule_init(entry->lsm[i].type,
                                                           Audit_equal,
                                                           entry->lsm[i].args_p,
                                                           &entry->lsm[i].rule);
                        BUG_ON(!entry->lsm[i].rule);
                }
        }
}

/**
 * ima_match_rules - determine whether an inode matches the measure rule.
 * @rule: a pointer to a rule
 * @inode: a pointer to an inode
 * @func: LIM hook identifier
 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 *
 * Returns true on rule match, false on failure.
 */
static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
                            enum ima_hooks func, int mask)
{
        struct task_struct *tsk = current;
        const struct cred *cred = current_cred();
        int i;

        if ((rule->flags & IMA_FUNC) &&
            (rule->func != func && func != POST_SETATTR))
                return false;
        if ((rule->flags & IMA_MASK) &&
            (rule->mask != mask && func != POST_SETATTR))
                return false;
        if ((rule->flags & IMA_INMASK) &&
            (!(rule->mask & mask) && func != POST_SETATTR))
                return false;
        if ((rule->flags & IMA_FSMAGIC)
            && rule->fsmagic != inode->i_sb->s_magic)
                return false;
        if ((rule->flags & IMA_FSUUID) &&
            memcmp(rule->fsuuid, inode->i_sb->s_uuid, sizeof(rule->fsuuid)))
                return false;
        if ((rule->flags & IMA_UID) && !uid_eq(rule->uid, cred->uid))
                return false;
        if (rule->flags & IMA_EUID) {
                if (has_capability_noaudit(current, CAP_SETUID)) {
                        if (!uid_eq(rule->uid, cred->euid)
                            && !uid_eq(rule->uid, cred->suid)
                            && !uid_eq(rule->uid, cred->uid))
                                return false;
                } else if (!uid_eq(rule->uid, cred->euid))
                        return false;
        }

        if ((rule->flags & IMA_FOWNER) && !uid_eq(rule->fowner, inode->i_uid))
                return false;
        for (i = 0; i < MAX_LSM_RULES; i++) {
                int rc = 0;
                u32 osid, sid;
                int retried = 0;

                if (!rule->lsm[i].rule)
                        continue;
retry:
                switch (i) {
                case LSM_OBJ_USER:
                case LSM_OBJ_ROLE:
                case LSM_OBJ_TYPE:
                        security_inode_getsecid(inode, &osid);
                        rc = security_filter_rule_match(osid,
                                                        rule->lsm[i].type,
                                                        Audit_equal,
                                                        rule->lsm[i].rule,
                                                        NULL);
                        break;
                case LSM_SUBJ_USER:
                case LSM_SUBJ_ROLE:
                case LSM_SUBJ_TYPE:
                        security_task_getsecid(tsk, &sid);
                        rc = security_filter_rule_match(sid,
                                                        rule->lsm[i].type,
                                                        Audit_equal,
                                                        rule->lsm[i].rule,
                                                        NULL);
                default:
                        break;
                }
                if ((rc < 0) && (!retried)) {
                        retried = 1;
                        ima_lsm_update_rules();
                        goto retry;
                }
                if (!rc)
                        return false;
        }
        return true;
}

/*
 * In addition to knowing that we need to appraise the file in general,
 * we need to differentiate between calling hooks, for hook specific rules.
 */
static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
{
        if (!(rule->flags & IMA_FUNC))
                return IMA_FILE_APPRAISE;

        switch (func) {
        case MMAP_CHECK:
                return IMA_MMAP_APPRAISE;
        case BPRM_CHECK:
                return IMA_BPRM_APPRAISE;
        case FILE_CHECK:
        case POST_SETATTR:
                return IMA_FILE_APPRAISE;
        case MODULE_CHECK ... MAX_CHECK - 1:
        default:
                return IMA_READ_APPRAISE;
        }
}

/**
 * ima_match_policy - decision based on LSM and other conditions
 * @inode: pointer to an inode for which the policy decision is being made
 * @func: IMA hook identifier
 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 * @pcr: set the pcr to extend
 *
 * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
 * conditions.
 *
 * Since the IMA policy may be updated multiple times we need to lock the
 * list when walking it.  Reads are many orders of magnitude more numerous
 * than writes so ima_match_policy() is classical RCU candidate.
 */
int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
                     int flags, int *pcr)
{
        struct ima_rule_entry *entry;
        int action = 0, actmask = flags | (flags << 1);

        rcu_read_lock();
        list_for_each_entry_rcu(entry, ima_rules, list) {

                if (!(entry->action & actmask))
                        continue;

                if (!ima_match_rules(entry, inode, func, mask))
                        continue;

                action |= entry->flags & IMA_ACTION_FLAGS;

                action |= entry->action & IMA_DO_MASK;
                if (entry->action & IMA_APPRAISE)
                        action |= get_subaction(entry, func);

                if (entry->action & IMA_DO_MASK)
                        actmask &= ~(entry->action | entry->action << 1);
                else
                        actmask &= ~(entry->action | entry->action >> 1);

                if ((pcr) && (entry->flags & IMA_PCR))
                        *pcr = entry->pcr;

                if (!actmask)
                        break;
        }
        rcu_read_unlock();

        return action;
}

/*
 * Initialize the ima_policy_flag variable based on the currently
 * loaded policy.  Based on this flag, the decision to short circuit
 * out of a function or not call the function in the first place
 * can be made earlier.
 */
void ima_update_policy_flag(void)
{
        struct ima_rule_entry *entry;

        list_for_each_entry(entry, ima_rules, list) {
                if (entry->action & IMA_DO_MASK)
                        ima_policy_flag |= entry->action;
        }

        ima_appraise |= temp_ima_appraise;
        if (!ima_appraise)
                ima_policy_flag &= ~IMA_APPRAISE;
}

/**
 * ima_init_policy - initialize the default measure rules.
 *
 * ima_rules points to either the ima_default_rules or the
 * the new ima_policy_rules.
 */
void __init ima_init_policy(void)
{
        int i, measure_entries, appraise_entries;

        /* if !ima_policy set entries = 0 so we load NO default rules */
        measure_entries = ima_policy ? ARRAY_SIZE(dont_measure_rules) : 0;
        appraise_entries = ima_use_appraise_tcb ?
                         ARRAY_SIZE(default_appraise_rules) : 0;

        for (i = 0; i < measure_entries; i++)
                list_add_tail(&dont_measure_rules[i].list, &ima_default_rules);

        switch (ima_policy) {
        case ORIGINAL_TCB:
                for (i = 0; i < ARRAY_SIZE(original_measurement_rules); i++)
                        list_add_tail(&original_measurement_rules[i].list,
                                      &ima_default_rules);
                break;
        case DEFAULT_TCB:
                for (i = 0; i < ARRAY_SIZE(default_measurement_rules); i++)
                        list_add_tail(&default_measurement_rules[i].list,
                                      &ima_default_rules);
        default:
                break;
        }

        for (i = 0; i < appraise_entries; i++) {
                list_add_tail(&default_appraise_rules[i].list,
                              &ima_default_rules);
                if (default_appraise_rules[i].func == POLICY_CHECK)
                        temp_ima_appraise |= IMA_APPRAISE_POLICY;
        }

        ima_rules = &ima_default_rules;
        ima_update_policy_flag();
}

/* Make sure we have a valid policy, at least containing some rules. */
int ima_check_policy(void)
{
        if (list_empty(&ima_temp_rules))
                return -EINVAL;
        return 0;
}

/**
 * ima_update_policy - update default_rules with new measure rules
 *
 * Called on file .release to update the default rules with a complete new
 * policy.  What we do here is to splice ima_policy_rules and ima_temp_rules so
 * they make a queue.  The policy may be updated multiple times and this is the
 * RCU updater.
 *
 * Policy rules are never deleted so ima_policy_flag gets zeroed only once when
 * we switch from the default policy to user defined.
 */
void ima_update_policy(void)
{
        struct list_head *first, *last, *policy;

        /* append current policy with the new rules */
        first = (&ima_temp_rules)->next;
        last = (&ima_temp_rules)->prev;
        policy = &ima_policy_rules;

        synchronize_rcu();

        last->next = policy;
        rcu_assign_pointer(list_next_rcu(policy->prev), first);
        first->prev = policy->prev;
        policy->prev = last;

        /* prepare for the next policy rules addition */
        INIT_LIST_HEAD(&ima_temp_rules);

        if (ima_rules != policy) {
                ima_policy_flag = 0;
                ima_rules = policy;
        }
        ima_update_policy_flag();
}

enum {
        Opt_err = -1,
        Opt_measure = 1, Opt_dont_measure,
        Opt_appraise, Opt_dont_appraise,
        Opt_audit,
        Opt_obj_user, Opt_obj_role, Opt_obj_type,
        Opt_subj_user, Opt_subj_role, Opt_subj_type,
        Opt_func, Opt_mask, Opt_fsmagic,
        Opt_fsuuid, Opt_uid, Opt_euid, Opt_fowner,
        Opt_appraise_type, Opt_permit_directio,
        Opt_pcr
};

static match_table_t policy_tokens = {
        {Opt_measure, "measure"},
        {Opt_dont_measure, "dont_measure"},
        {Opt_appraise, "appraise"},
        {Opt_dont_appraise, "dont_appraise"},
        {Opt_audit, "audit"},
        {Opt_obj_user, "obj_user=%s"},
        {Opt_obj_role, "obj_role=%s"},
        {Opt_obj_type, "obj_type=%s"},
        {Opt_subj_user, "subj_user=%s"},
        {Opt_subj_role, "subj_role=%s"},
        {Opt_subj_type, "subj_type=%s"},
        {Opt_func, "func=%s"},
        {Opt_mask, "mask=%s"},
        {Opt_fsmagic, "fsmagic=%s"},
        {Opt_fsuuid, "fsuuid=%s"},
        {Opt_uid, "uid=%s"},
        {Opt_euid, "euid=%s"},
        {Opt_fowner, "fowner=%s"},
        {Opt_appraise_type, "appraise_type=%s"},
        {Opt_permit_directio, "permit_directio"},
        {Opt_pcr, "pcr=%s"},
        {Opt_err, NULL}
};

static int ima_lsm_rule_init(struct ima_rule_entry *entry,
                             substring_t *args, int lsm_rule, int audit_type)
{
        int result;

        if (entry->lsm[lsm_rule].rule)
                return -EINVAL;

        entry->lsm[lsm_rule].args_p = match_strdup(args);
        if (!entry->lsm[lsm_rule].args_p)
                return -ENOMEM;

        entry->lsm[lsm_rule].type = audit_type;
        result = security_filter_rule_init(entry->lsm[lsm_rule].type,
                                           Audit_equal,
                                           entry->lsm[lsm_rule].args_p,
                                           &entry->lsm[lsm_rule].rule);
        if (!entry->lsm[lsm_rule].rule) {
                kfree(entry->lsm[lsm_rule].args_p);
                return -EINVAL;
        }

        return result;
}

static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
{
        audit_log_format(ab, "%s=", key);
        audit_log_untrustedstring(ab, value);
        audit_log_format(ab, " ");
}

static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
{
        struct audit_buffer *ab;
        char *from;
        char *p;
        int result = 0;

        ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);

        entry->uid = INVALID_UID;
        entry->fowner = INVALID_UID;
        entry->action = UNKNOWN;
        while ((p = strsep(&rule, " \t")) != NULL) {
                substring_t args[MAX_OPT_ARGS];
                int token;
                unsigned long lnum;

                if (result < 0)
                        break;
                if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
                        continue;
                token = match_token(p, policy_tokens, args);
                switch (token) {
                case Opt_measure:
                        ima_log_string(ab, "action", "measure");

                        if (entry->action != UNKNOWN)
                                result = -EINVAL;

                        entry->action = MEASURE;
                        break;
                case Opt_dont_measure:
                        ima_log_string(ab, "action", "dont_measure");

                        if (entry->action != UNKNOWN)
                                result = -EINVAL;

                        entry->action = DONT_MEASURE;
                        break;
                case Opt_appraise:
                        ima_log_string(ab, "action", "appraise");

                        if (entry->action != UNKNOWN)
                                result = -EINVAL;

                        entry->action = APPRAISE;
                        break;
                case Opt_dont_appraise:
                        ima_log_string(ab, "action", "dont_appraise");

                        if (entry->action != UNKNOWN)
                                result = -EINVAL;

                        entry->action = DONT_APPRAISE;
                        break;
                case Opt_audit:
                        ima_log_string(ab, "action", "audit");

                        if (entry->action != UNKNOWN)
                                result = -EINVAL;

                        entry->action = AUDIT;
                        break;
                case Opt_func:
                        ima_log_string(ab, "func", args[0].from);

                        if (entry->func)
                                result = -EINVAL;

                        if (strcmp(args[0].from, "FILE_CHECK") == 0)
                                entry->func = FILE_CHECK;
                        /* PATH_CHECK is for backwards compat */
                        else if (strcmp(args[0].from, "PATH_CHECK") == 0)
                                entry->func = FILE_CHECK;
                        else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
                                entry->func = MODULE_CHECK;
                        else if (strcmp(args[0].from, "FIRMWARE_CHECK") == 0)
                                entry->func = FIRMWARE_CHECK;
                        else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
                                || (strcmp(args[0].from, "MMAP_CHECK") == 0))
                                entry->func = MMAP_CHECK;
                        else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
                                entry->func = BPRM_CHECK;
                        else if (strcmp(args[0].from, "KEXEC_KERNEL_CHECK") ==
                                 0)
                                entry->func = KEXEC_KERNEL_CHECK;
                        else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK")
                                 == 0)
                                entry->func = KEXEC_INITRAMFS_CHECK;
                        else if (strcmp(args[0].from, "POLICY_CHECK") == 0)
                                entry->func = POLICY_CHECK;
                        else
                                result = -EINVAL;
                        if (!result)
                                entry->flags |= IMA_FUNC;
                        break;
                case Opt_mask:
                        ima_log_string(ab, "mask", args[0].from);

                        if (entry->mask)
                                result = -EINVAL;

                        from = args[0].from;
                        if (*from == '^')
                                from++;

                        if ((strcmp(from, "MAY_EXEC")) == 0)
                                entry->mask = MAY_EXEC;
                        else if (strcmp(from, "MAY_WRITE") == 0)
                                entry->mask = MAY_WRITE;
                        else if (strcmp(from, "MAY_READ") == 0)
                                entry->mask = MAY_READ;
                        else if (strcmp(from, "MAY_APPEND") == 0)
                                entry->mask = MAY_APPEND;
                        else
                                result = -EINVAL;
                        if (!result)
                                entry->flags |= (*args[0].from == '^')
                                     ? IMA_INMASK : IMA_MASK;
                        break;
                case Opt_fsmagic:
                        ima_log_string(ab, "fsmagic", args[0].from);

                        if (entry->fsmagic) {
                                result = -EINVAL;
                                break;
                        }

                        result = kstrtoul(args[0].from, 16, &entry->fsmagic);
                        if (!result)
                                entry->flags |= IMA_FSMAGIC;
                        break;
                case Opt_fsuuid:
                        ima_log_string(ab, "fsuuid", args[0].from);

                        if (memchr_inv(entry->fsuuid, 0x00,
                                       sizeof(entry->fsuuid))) {
                                result = -EINVAL;
                                break;
                        }

                        result = blk_part_pack_uuid(args[0].from,
                                                    entry->fsuuid);
                        if (!result)
                                entry->flags |= IMA_FSUUID;
                        break;
                case Opt_uid:
                        ima_log_string(ab, "uid", args[0].from);
                case Opt_euid:
                        if (token == Opt_euid)
                                ima_log_string(ab, "euid", args[0].from);

                        if (uid_valid(entry->uid)) {
                                result = -EINVAL;
                                break;
                        }

                        result = kstrtoul(args[0].from, 10, &lnum);
                        if (!result) {
                                entry->uid = make_kuid(current_user_ns(),
                                                       (uid_t) lnum);
                                if (!uid_valid(entry->uid) ||
                                    (uid_t)lnum != lnum)
                                        result = -EINVAL;
                                else
                                        entry->flags |= (token == Opt_uid)
                                            ? IMA_UID : IMA_EUID;
                        }
                        break;
                case Opt_fowner:
                        ima_log_string(ab, "fowner", args[0].from);

                        if (uid_valid(entry->fowner)) {
                                result = -EINVAL;
                                break;
                        }

                        result = kstrtoul(args[0].from, 10, &lnum);
                        if (!result) {
                                entry->fowner = make_kuid(current_user_ns(), (uid_t)lnum);
                                if (!uid_valid(entry->fowner) || (((uid_t)lnum) != lnum))
                                        result = -EINVAL;
                                else
                                        entry->flags |= IMA_FOWNER;
                        }
                        break;
                case Opt_obj_user:
                        ima_log_string(ab, "obj_user", args[0].from);
                        result = ima_lsm_rule_init(entry, args,
                                                   LSM_OBJ_USER,
                                                   AUDIT_OBJ_USER);
                        break;
                case Opt_obj_role:
                        ima_log_string(ab, "obj_role", args[0].from);
                        result = ima_lsm_rule_init(entry, args,
                                                   LSM_OBJ_ROLE,
                                                   AUDIT_OBJ_ROLE);
                        break;
                case Opt_obj_type:
                        ima_log_string(ab, "obj_type", args[0].from);
                        result = ima_lsm_rule_init(entry, args,
                                                   LSM_OBJ_TYPE,
                                                   AUDIT_OBJ_TYPE);
                        break;
                case Opt_subj_user:
                        ima_log_string(ab, "subj_user", args[0].from);
                        result = ima_lsm_rule_init(entry, args,
                                                   LSM_SUBJ_USER,
                                                   AUDIT_SUBJ_USER);
                        break;
                case Opt_subj_role:
                        ima_log_string(ab, "subj_role", args[0].from);
                        result = ima_lsm_rule_init(entry, args,
                                                   LSM_SUBJ_ROLE,
                                                   AUDIT_SUBJ_ROLE);
                        break;
                case Opt_subj_type:
                        ima_log_string(ab, "subj_type", args[0].from);
                        result = ima_lsm_rule_init(entry, args,
                                                   LSM_SUBJ_TYPE,
                                                   AUDIT_SUBJ_TYPE);
                        break;
                case Opt_appraise_type:
                        if (entry->action != APPRAISE) {
                                result = -EINVAL;
                                break;
                        }

                        ima_log_string(ab, "appraise_type", args[0].from);
                        if ((strcmp(args[0].from, "imasig")) == 0)
                                entry->flags |= IMA_DIGSIG_REQUIRED;
                        else
                                result = -EINVAL;
                        break;
                case Opt_permit_directio:
                        entry->flags |= IMA_PERMIT_DIRECTIO;
                        break;
                case Opt_pcr:
                        if (entry->action != MEASURE) {
                                result = -EINVAL;
                                break;
                        }
                        ima_log_string(ab, "pcr", args[0].from);

                        result = kstrtoint(args[0].from, 10, &entry->pcr);
                        if (result || INVALID_PCR(entry->pcr))
                                result = -EINVAL;
                        else
                                entry->flags |= IMA_PCR;

                        break;
                case Opt_err:
                        ima_log_string(ab, "UNKNOWN", p);
                        result = -EINVAL;
                        break;
                }
        }
        if (!result && (entry->action == UNKNOWN))
                result = -EINVAL;
        else if (entry->func == MODULE_CHECK)
                temp_ima_appraise |= IMA_APPRAISE_MODULES;
        else if (entry->func == FIRMWARE_CHECK)
                temp_ima_appraise |= IMA_APPRAISE_FIRMWARE;
        else if (entry->func == POLICY_CHECK)
                temp_ima_appraise |= IMA_APPRAISE_POLICY;
        audit_log_format(ab, "res=%d", !result);
        audit_log_end(ab);
        return result;
}

/**
 * ima_parse_add_rule - add a rule to ima_policy_rules
 * @rule - ima measurement policy rule
 *
 * Avoid locking by allowing just one writer at a time in ima_write_policy()
 * Returns the length of the rule parsed, an error code on failure
 */
ssize_t ima_parse_add_rule(char *rule)
{
        static const char op[] = "update_policy";
        char *p;
        struct ima_rule_entry *entry;
        ssize_t result, len;
        int audit_info = 0;

        p = strsep(&rule, "\n");
        len = strlen(p) + 1;
        p += strspn(p, " \t");

        if (*p == '#' || *p == '\0')
                return len;

        entry = kzalloc(sizeof(*entry), GFP_KERNEL);
        if (!entry) {
                integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
                                    NULL, op, "-ENOMEM", -ENOMEM, audit_info);
                return -ENOMEM;
        }

        INIT_LIST_HEAD(&entry->list);

        result = ima_parse_rule(p, entry);
        if (result) {
                kfree(entry);
                integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
                                    NULL, op, "invalid-policy", result,
                                    audit_info);
                return result;
        }

        list_add_tail(&entry->list, &ima_temp_rules);

        return len;
}

/**
 * ima_delete_rules() called to cleanup invalid in-flight policy.
 * We don't need locking as we operate on the temp list, which is
 * different from the active one.  There is also only one user of
 * ima_delete_rules() at a time.
 */
void ima_delete_rules(void)
{
        struct ima_rule_entry *entry, *tmp;
        int i;

        temp_ima_appraise = 0;
        list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
                for (i = 0; i < MAX_LSM_RULES; i++)
                        kfree(entry->lsm[i].args_p);

                list_del(&entry->list);
                kfree(entry);
        }
}

#ifdef  CONFIG_IMA_READ_POLICY
enum {
        mask_exec = 0, mask_write, mask_read, mask_append
};

static char *mask_tokens[] = {
        "MAY_EXEC",
        "MAY_WRITE",
        "MAY_READ",
        "MAY_APPEND"
};

enum {
        func_file = 0, func_mmap, func_bprm,
        func_module, func_firmware, func_post,
        func_kexec_kernel, func_kexec_initramfs,
        func_policy
};

static char *func_tokens[] = {
        "FILE_CHECK",
        "MMAP_CHECK",
        "BPRM_CHECK",
        "MODULE_CHECK",
        "FIRMWARE_CHECK",
        "POST_SETATTR",
        "KEXEC_KERNEL_CHECK",
        "KEXEC_INITRAMFS_CHECK",
        "POLICY_CHECK"
};

void *ima_policy_start(struct seq_file *m, loff_t *pos)
{
        loff_t l = *pos;
        struct ima_rule_entry *entry;

        rcu_read_lock();
        list_for_each_entry_rcu(entry, ima_rules, list) {
                if (!l--) {
                        rcu_read_unlock();
                        return entry;
                }
        }
        rcu_read_unlock();
        return NULL;
}

void *ima_policy_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct ima_rule_entry *entry = v;

        rcu_read_lock();
        entry = list_entry_rcu(entry->list.next, struct ima_rule_entry, list);
        rcu_read_unlock();
        (*pos)++;

        return (&entry->list == ima_rules) ? NULL : entry;
}

void ima_policy_stop(struct seq_file *m, void *v)
{
}

#define pt(token)       policy_tokens[token + Opt_err].pattern
#define mt(token)       mask_tokens[token]
#define ft(token)       func_tokens[token]

/*
 * policy_func_show - display the ima_hooks policy rule
 */
static void policy_func_show(struct seq_file *m, enum ima_hooks func)
{
        char tbuf[64] = {0,};

        switch (func) {
        case FILE_CHECK:
                seq_printf(m, pt(Opt_func), ft(func_file));
                break;
        case MMAP_CHECK:
                seq_printf(m, pt(Opt_func), ft(func_mmap));
                break;
        case BPRM_CHECK:
                seq_printf(m, pt(Opt_func), ft(func_bprm));
                break;
        case MODULE_CHECK:
                seq_printf(m, pt(Opt_func), ft(func_module));
                break;
        case FIRMWARE_CHECK:
                seq_printf(m, pt(Opt_func), ft(func_firmware));
                break;
        case POST_SETATTR:
                seq_printf(m, pt(Opt_func), ft(func_post));
                break;
        case KEXEC_KERNEL_CHECK:
                seq_printf(m, pt(Opt_func), ft(func_kexec_kernel));
                break;
        case KEXEC_INITRAMFS_CHECK:
                seq_printf(m, pt(Opt_func), ft(func_kexec_initramfs));
                break;
        case POLICY_CHECK:
                seq_printf(m, pt(Opt_func), ft(func_policy));
                break;
        default:
                snprintf(tbuf, sizeof(tbuf), "%d", func);
                seq_printf(m, pt(Opt_func), tbuf);
                break;
        }
        seq_puts(m, " ");
}

int ima_policy_show(struct seq_file *m, void *v)
{
        struct ima_rule_entry *entry = v;
        int i;

        char tbuf[64] = {0,};

        rcu_read_lock();

        if (entry->action & MEASURE)
                seq_puts(m, pt(Opt_measure));
        if (entry->action & DONT_MEASURE)
                seq_puts(m, pt(Opt_dont_measure));
        if (entry->action & APPRAISE)
                seq_puts(m, pt(Opt_appraise));
        if (entry->action & DONT_APPRAISE)
                seq_puts(m, pt(Opt_dont_appraise));
        if (entry->action & AUDIT)
                seq_puts(m, pt(Opt_audit));

        seq_puts(m, " ");

        if (entry->flags & IMA_FUNC)
                policy_func_show(m, entry->func);

        if (entry->flags & IMA_MASK) {
                if (entry->mask & MAY_EXEC)
                        seq_printf(m, pt(Opt_mask), mt(mask_exec));
                if (entry->mask & MAY_WRITE)
                        seq_printf(m, pt(Opt_mask), mt(mask_write));
                if (entry->mask & MAY_READ)
                        seq_printf(m, pt(Opt_mask), mt(mask_read));
                if (entry->mask & MAY_APPEND)
                        seq_printf(m, pt(Opt_mask), mt(mask_append));
                seq_puts(m, " ");
        }

        if (entry->flags & IMA_FSMAGIC) {
                snprintf(tbuf, sizeof(tbuf), "0x%lx", entry->fsmagic);
                seq_printf(m, pt(Opt_fsmagic), tbuf);
                seq_puts(m, " ");
        }

        if (entry->flags & IMA_PCR) {
                snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr);
                seq_printf(m, pt(Opt_pcr), tbuf);
                seq_puts(m, " ");
        }

        if (entry->flags & IMA_FSUUID) {
                seq_printf(m, "fsuuid=%pU", entry->fsuuid);
                seq_puts(m, " ");
        }

        if (entry->flags & IMA_UID) {
                snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
                seq_printf(m, pt(Opt_uid), tbuf);
                seq_puts(m, " ");
        }

        if (entry->flags & IMA_EUID) {
                snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
                seq_printf(m, pt(Opt_euid), tbuf);
                seq_puts(m, " ");
        }

        if (entry->flags & IMA_FOWNER) {
                snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner));
                seq_printf(m, pt(Opt_fowner), tbuf);
                seq_puts(m, " ");
        }

        for (i = 0; i < MAX_LSM_RULES; i++) {
                if (entry->lsm[i].rule) {
                        switch (i) {
                        case LSM_OBJ_USER:
                                seq_printf(m, pt(Opt_obj_user),
                                           (char *)entry->lsm[i].args_p);
                                break;
                        case LSM_OBJ_ROLE:
                                seq_printf(m, pt(Opt_obj_role),
                                           (char *)entry->lsm[i].args_p);
                                break;
                        case LSM_OBJ_TYPE:
                                seq_printf(m, pt(Opt_obj_type),
                                           (char *)entry->lsm[i].args_p);
                                break;
                        case LSM_SUBJ_USER:
                                seq_printf(m, pt(Opt_subj_user),
                                           (char *)entry->lsm[i].args_p);
                                break;
                        case LSM_SUBJ_ROLE:
                                seq_printf(m, pt(Opt_subj_role),
                                           (char *)entry->lsm[i].args_p);
                                break;
                        case LSM_SUBJ_TYPE:
                                seq_printf(m, pt(Opt_subj_type),
                                           (char *)entry->lsm[i].args_p);
                                break;
                        }
                }
        }
        if (entry->flags & IMA_DIGSIG_REQUIRED)
                seq_puts(m, "appraise_type=imasig ");
        if (entry->flags & IMA_PERMIT_DIRECTIO)
                seq_puts(m, "permit_directio ");
        rcu_read_unlock();
        seq_puts(m, "\n");
        return 0;
}
#endif  /* CONFIG_IMA_READ_POLICY */