// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2008 IBM Corporation
 * Author: Mimi Zohar <zohar@us.ibm.com>
 *
 * ima_policy.c
 *      - initialize default measure policy rules
 */

#include <linux/init.h>
#include <linux/list.h>
#include <linux/kernel_read_file.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 <linux/ima.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 IMA_FSNAME      0x0200
#define IMA_KEYRINGS    0x0400
#define IMA_LABEL       0x0800
#define IMA_VALIDATE_ALGOS      0x1000

#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 HASH            0x0100
#define DONT_HASH       0x0200

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

int ima_policy_flag;
static int temp_ima_appraise;
static int build_ima_appraise __ro_after_init;

atomic_t ima_setxattr_allowed_hash_algorithms;

#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 };

enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY };

struct ima_rule_opt_list {
        size_t count;
        char *items[];
};

struct ima_rule_entry {
        struct list_head list;
        int action;
        unsigned int flags;
        enum ima_hooks func;
        int mask;
        unsigned long fsmagic;
        uuid_t fsuuid;
        kuid_t uid;
        kuid_t fowner;
        bool (*uid_op)(kuid_t, kuid_t);    /* Handlers for operators       */
        bool (*fowner_op)(kuid_t, kuid_t); /* uid_eq(), uid_gt(), uid_lt() */
        int pcr;
        unsigned int allowed_algos; /* bitfield of allowed hash algorithms */
        struct {
                void *rule;     /* LSM file metadata specific */
                char *args_p;   /* audit value */
                int type;       /* audit type */
        } lsm[MAX_LSM_RULES];
        char *fsname;
        struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */
        struct ima_rule_opt_list *label; /* Measure data grouped under this label */
        struct ima_template_desc *template;
};

/*
 * sanity check in case the kernels gains more hash algorithms that can
 * fit in an unsigned int
 */
static_assert(
        8 * sizeof(unsigned int) >= HASH_ALGO__LAST,
        "The bitfield allowed_algos in ima_rule_entry is too small to contain all the supported hash algorithms, consider using a bigger type");

/*
 * 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[] __ro_after_init = {
        {.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 = SMACK_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = CGROUP_SUPER_MAGIC,
         .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = CGROUP2_SUPER_MAGIC,
         .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC}
};

static struct ima_rule_entry original_measurement_rules[] __ro_after_init = {
        {.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, .uid_op = &uid_eq,
         .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[] __ro_after_init = {
        {.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, .uid_op = &uid_eq,
         .flags = IMA_FUNC | IMA_INMASK | IMA_EUID},
        {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
         .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
         .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[] __ro_after_init = {
        {.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 = SMACK_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
        {.action = DONT_APPRAISE, .fsmagic = CGROUP2_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, .fowner_op = &uid_eq,
         .flags = IMA_FOWNER},
#else
        /* force signature */
        {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
         .flags = IMA_FOWNER | IMA_DIGSIG_REQUIRED},
#endif
};

static struct ima_rule_entry build_appraise_rules[] __ro_after_init = {
#ifdef CONFIG_IMA_APPRAISE_REQUIRE_MODULE_SIGS
        {.action = APPRAISE, .func = MODULE_CHECK,
         .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
#endif
#ifdef CONFIG_IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS
        {.action = APPRAISE, .func = FIRMWARE_CHECK,
         .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
#endif
#ifdef CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS
        {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
         .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
#endif
#ifdef CONFIG_IMA_APPRAISE_REQUIRE_POLICY_SIGS
        {.action = APPRAISE, .func = POLICY_CHECK,
         .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
#endif
};

static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
        {.action = APPRAISE, .func = MODULE_CHECK,
         .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
        {.action = APPRAISE, .func = FIRMWARE_CHECK,
         .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
        {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
         .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
        {.action = APPRAISE, .func = POLICY_CHECK,
         .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
};

static struct ima_rule_entry critical_data_rules[] __ro_after_init = {
        {.action = MEASURE, .func = CRITICAL_DATA, .flags = IMA_FUNC},
};

/* An array of architecture specific rules */
static struct ima_rule_entry *arch_policy_entry __ro_after_init;

static LIST_HEAD(ima_default_rules);
static LIST_HEAD(ima_policy_rules);
static LIST_HEAD(ima_temp_rules);
static struct list_head *ima_rules = &ima_default_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 bool ima_use_appraise_tcb __initdata;
static bool ima_use_secure_boot __initdata;
static bool ima_use_critical_data __initdata;
static bool ima_fail_unverifiable_sigs __ro_after_init;
static int __init policy_setup(char *str)
{
        char *p;

        while ((p = strsep(&str, " |\n")) != NULL) {
                if (*p == ' ')
                        continue;
                if ((strcmp(p, "tcb") == 0) && !ima_policy)
                        ima_policy = DEFAULT_TCB;
                else if (strcmp(p, "appraise_tcb") == 0)
                        ima_use_appraise_tcb = true;
                else if (strcmp(p, "secure_boot") == 0)
                        ima_use_secure_boot = true;
                else if (strcmp(p, "critical_data") == 0)
                        ima_use_critical_data = true;
                else if (strcmp(p, "fail_securely") == 0)
                        ima_fail_unverifiable_sigs = true;
                else
                        pr_err("policy \"%s\" not found", p);
        }

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

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

static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
{
        struct ima_rule_opt_list *opt_list;
        size_t count = 0;
        char *src_copy;
        char *cur, *next;
        size_t i;

        src_copy = match_strdup(src);
        if (!src_copy)
                return ERR_PTR(-ENOMEM);

        next = src_copy;
        while ((cur = strsep(&next, "|"))) {
                /* Don't accept an empty list item */
                if (!(*cur)) {
                        kfree(src_copy);
                        return ERR_PTR(-EINVAL);
                }
                count++;
        }

        /* Don't accept an empty list */
        if (!count) {
                kfree(src_copy);
                return ERR_PTR(-EINVAL);
        }

        opt_list = kzalloc(struct_size(opt_list, items, count), GFP_KERNEL);
        if (!opt_list) {
                kfree(src_copy);
                return ERR_PTR(-ENOMEM);
        }

        /*
         * strsep() has already replaced all instances of '|' with '\0',
         * leaving a byte sequence of NUL-terminated strings. Reference each
         * string with the array of items.
         *
         * IMPORTANT: Ownership of the allocated buffer is transferred from
         * src_copy to the first element in the items array. To free the
         * buffer, kfree() must only be called on the first element of the
         * array.
         */
        for (i = 0, cur = src_copy; i < count; i++) {
                opt_list->items[i] = cur;
                cur = strchr(cur, '\0') + 1;
        }
        opt_list->count = count;

        return opt_list;
}

static void ima_free_rule_opt_list(struct ima_rule_opt_list *opt_list)
{
        if (!opt_list)
                return;

        if (opt_list->count) {
                kfree(opt_list->items[0]);
                opt_list->count = 0;
        }

        kfree(opt_list);
}

static void ima_lsm_free_rule(struct ima_rule_entry *entry)
{
        int i;

        for (i = 0; i < MAX_LSM_RULES; i++) {
                ima_filter_rule_free(entry->lsm[i].rule);
                kfree(entry->lsm[i].args_p);
        }
}

static void ima_free_rule(struct ima_rule_entry *entry)
{
        if (!entry)
                return;

        /*
         * entry->template->fields may be allocated in ima_parse_rule() but that
         * reference is owned by the corresponding ima_template_desc element in
         * the defined_templates list and cannot be freed here
         */
        kfree(entry->fsname);
        ima_free_rule_opt_list(entry->keyrings);
        ima_lsm_free_rule(entry);
        kfree(entry);
}

static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
{
        struct ima_rule_entry *nentry;
        int i;

        /*
         * Immutable elements are copied over as pointers and data; only
         * lsm rules can change
         */
        nentry = kmemdup(entry, sizeof(*nentry), GFP_KERNEL);
        if (!nentry)
                return NULL;

        memset(nentry->lsm, 0, sizeof_field(struct ima_rule_entry, lsm));

        for (i = 0; i < MAX_LSM_RULES; i++) {
                if (!entry->lsm[i].args_p)
                        continue;

                nentry->lsm[i].type = entry->lsm[i].type;
                nentry->lsm[i].args_p = entry->lsm[i].args_p;
                /*
                 * Remove the reference from entry so that the associated
                 * memory will not be freed during a later call to
                 * ima_lsm_free_rule(entry).
                 */
                entry->lsm[i].args_p = NULL;

                ima_filter_rule_init(nentry->lsm[i].type, Audit_equal,
                                     nentry->lsm[i].args_p,
                                     &nentry->lsm[i].rule);
                if (!nentry->lsm[i].rule)
                        pr_warn("rule for LSM \'%s\' is undefined\n",
                                nentry->lsm[i].args_p);
        }
        return nentry;
}

static int ima_lsm_update_rule(struct ima_rule_entry *entry)
{
        struct ima_rule_entry *nentry;

        nentry = ima_lsm_copy_rule(entry);
        if (!nentry)
                return -ENOMEM;

        list_replace_rcu(&entry->list, &nentry->list);
        synchronize_rcu();
        /*
         * ima_lsm_copy_rule() shallow copied all references, except for the
         * LSM references, from entry to nentry so we only want to free the LSM
         * references and the entry itself. All other memory refrences will now
         * be owned by nentry.
         */
        ima_lsm_free_rule(entry);
        kfree(entry);

        return 0;
}

static bool ima_rule_contains_lsm_cond(struct ima_rule_entry *entry)
{
        int i;

        for (i = 0; i < MAX_LSM_RULES; i++)
                if (entry->lsm[i].args_p)
                        return true;

        return false;
}

/*
 * 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.
 */
static void ima_lsm_update_rules(void)
{
        struct ima_rule_entry *entry, *e;
        int result;

        list_for_each_entry_safe(entry, e, &ima_policy_rules, list) {
                if (!ima_rule_contains_lsm_cond(entry))
                        continue;

                result = ima_lsm_update_rule(entry);
                if (result) {
                        pr_err("lsm rule update error %d\n", result);
                        return;
                }
        }
}

int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
                          void *lsm_data)
{
        if (event != LSM_POLICY_CHANGE)
                return NOTIFY_DONE;

        ima_lsm_update_rules();
        return NOTIFY_OK;
}

/**
 * ima_match_rule_data - determine whether func_data matches the policy rule
 * @rule: a pointer to a rule
 * @func_data: data to match against the measure rule data
 * @cred: a pointer to a credentials structure for user validation
 *
 * Returns true if func_data matches one in the rule, false otherwise.
 */
static bool ima_match_rule_data(struct ima_rule_entry *rule,
                                const char *func_data,
                                const struct cred *cred)
{
        const struct ima_rule_opt_list *opt_list = NULL;
        bool matched = false;
        size_t i;

        if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
                return false;

        switch (rule->func) {
        case KEY_CHECK:
                if (!rule->keyrings)
                        return true;

                opt_list = rule->keyrings;
                break;
        case CRITICAL_DATA:
                if (!rule->label)
                        return true;

                opt_list = rule->label;
                break;
        default:
                return false;
        }

        if (!func_data)
                return false;

        for (i = 0; i < opt_list->count; i++) {
                if (!strcmp(opt_list->items[i], func_data)) {
                        matched = true;
                        break;
                }
        }

        return matched;
}

/**
 * ima_match_rules - determine whether an inode matches the policy rule.
 * @rule: a pointer to a rule
 * @mnt_userns: user namespace of the mount the inode was found from
 * @inode: a pointer to an inode
 * @cred: a pointer to a credentials structure for user validation
 * @secid: the secid of the task to be validated
 * @func: LIM hook identifier
 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 * @func_data: func specific data, may be NULL
 *
 * Returns true on rule match, false on failure.
 */
static bool ima_match_rules(struct ima_rule_entry *rule,
                            struct user_namespace *mnt_userns,
                            struct inode *inode, const struct cred *cred,
                            u32 secid, enum ima_hooks func, int mask,
                            const char *func_data)
{
        int i;

        if ((rule->flags & IMA_FUNC) &&
            (rule->func != func && func != POST_SETATTR))
                return false;

        switch (func) {
        case KEY_CHECK:
        case CRITICAL_DATA:
                return ((rule->func == func) &&
                        ima_match_rule_data(rule, func_data, cred));
        default:
                break;
        }

        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_FSNAME)
            && strcmp(rule->fsname, inode->i_sb->s_type->name))
                return false;
        if ((rule->flags & IMA_FSUUID) &&
            !uuid_equal(&rule->fsuuid, &inode->i_sb->s_uuid))
                return false;
        if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
                return false;
        if (rule->flags & IMA_EUID) {
                if (has_capability_noaudit(current, CAP_SETUID)) {
                        if (!rule->uid_op(cred->euid, rule->uid)
                            && !rule->uid_op(cred->suid, rule->uid)
                            && !rule->uid_op(cred->uid, rule->uid))
                                return false;
                } else if (!rule->uid_op(cred->euid, rule->uid))
                        return false;
        }

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

                if (!rule->lsm[i].rule) {
                        if (!rule->lsm[i].args_p)
                                continue;
                        else
                                return false;
                }
                switch (i) {
                case LSM_OBJ_USER:
                case LSM_OBJ_ROLE:
                case LSM_OBJ_TYPE:
                        security_inode_getsecid(inode, &osid);
                        rc = ima_filter_rule_match(osid, rule->lsm[i].type,
                                                   Audit_equal,
                                                   rule->lsm[i].rule);
                        break;
                case LSM_SUBJ_USER:
                case LSM_SUBJ_ROLE:
                case LSM_SUBJ_TYPE:
                        rc = ima_filter_rule_match(secid, rule->lsm[i].type,
                                                   Audit_equal,
                                                   rule->lsm[i].rule);
                        break;
                default:
                        break;
                }
                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 CREDS_CHECK:
                return IMA_CREDS_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
 * @mnt_userns: user namespace of the mount the inode was found from
 * @inode: pointer to an inode for which the policy decision is being made
 * @cred: pointer to a credentials structure for which the policy decision is
 *        being made
 * @secid: LSM secid of the task to be validated
 * @func: IMA hook identifier
 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 * @pcr: set the pcr to extend
 * @template_desc: the template that should be used for this rule
 * @func_data: func specific data, may be NULL
 * @allowed_algos: allowlist of hash algorithms for the IMA xattr
 *
 * 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 user_namespace *mnt_userns, struct inode *inode,
                     const struct cred *cred, u32 secid, enum ima_hooks func,
                     int mask, int flags, int *pcr,
                     struct ima_template_desc **template_desc,
                     const char *func_data, unsigned int *allowed_algos)
{
        struct ima_rule_entry *entry;
        int action = 0, actmask = flags | (flags << 1);

        if (template_desc && !*template_desc)
                *template_desc = ima_template_desc_current();

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

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

                if (!ima_match_rules(entry, mnt_userns, inode, cred, secid,
                                     func, mask, func_data))
                        continue;

                action |= entry->flags & IMA_ACTION_FLAGS;

                action |= entry->action & IMA_DO_MASK;
                if (entry->action & IMA_APPRAISE) {
                        action |= get_subaction(entry, func);
                        action &= ~IMA_HASH;
                        if (ima_fail_unverifiable_sigs)
                                action |= IMA_FAIL_UNVERIFIABLE_SIGS;

                        if (allowed_algos &&
                            entry->flags & IMA_VALIDATE_ALGOS)
                                *allowed_algos = entry->allowed_algos;
                }

                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 (template_desc && entry->template)
                        *template_desc = entry->template;

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

        return action;
}

/**
 * ima_update_policy_flags() - Update global IMA variables
 *
 * Update ima_policy_flag and ima_setxattr_allowed_hash_algorithms
 * based on the currently loaded policy.
 *
 * With ima_policy_flag, the decision to short circuit out of a function
 * or not call the function in the first place can be made earlier.
 *
 * With ima_setxattr_allowed_hash_algorithms, the policy can restrict the
 * set of hash algorithms accepted when updating the security.ima xattr of
 * a file.
 *
 * Context: called after a policy update and at system initialization.
 */
void ima_update_policy_flags(void)
{
        struct ima_rule_entry *entry;
        int new_policy_flag = 0;

        rcu_read_lock();
        list_for_each_entry(entry, ima_rules, list) {
                /*
                 * SETXATTR_CHECK rules do not implement a full policy check
                 * because rule checking would probably have an important
                 * performance impact on setxattr(). As a consequence, only one
                 * SETXATTR_CHECK can be active at a given time.
                 * Because we want to preserve that property, we set out to use
                 * atomic_cmpxchg. Either:
                 * - the atomic was non-zero: a setxattr hash policy is
                 *   already enforced, we do nothing
                 * - the atomic was zero: no setxattr policy was set, enable
                 *   the setxattr hash policy
                 */
                if (entry->func == SETXATTR_CHECK) {
                        atomic_cmpxchg(&ima_setxattr_allowed_hash_algorithms,
                                       0, entry->allowed_algos);
                        /* SETXATTR_CHECK doesn't impact ima_policy_flag */
                        continue;
                }

                if (entry->action & IMA_DO_MASK)
                        new_policy_flag |= entry->action;
        }
        rcu_read_unlock();

        ima_appraise |= (build_ima_appraise | temp_ima_appraise);
        if (!ima_appraise)
                new_policy_flag &= ~IMA_APPRAISE;

        ima_policy_flag = new_policy_flag;
}

static int ima_appraise_flag(enum ima_hooks func)
{
        if (func == MODULE_CHECK)
                return IMA_APPRAISE_MODULES;
        else if (func == FIRMWARE_CHECK)
                return IMA_APPRAISE_FIRMWARE;
        else if (func == POLICY_CHECK)
                return IMA_APPRAISE_POLICY;
        else if (func == KEXEC_KERNEL_CHECK)
                return IMA_APPRAISE_KEXEC;
        return 0;
}

static void add_rules(struct ima_rule_entry *entries, int count,
                      enum policy_rule_list policy_rule)
{
        int i = 0;

        for (i = 0; i < count; i++) {
                struct ima_rule_entry *entry;

                if (policy_rule & IMA_DEFAULT_POLICY)
                        list_add_tail(&entries[i].list, &ima_default_rules);

                if (policy_rule & IMA_CUSTOM_POLICY) {
                        entry = kmemdup(&entries[i], sizeof(*entry),
                                        GFP_KERNEL);
                        if (!entry)
                                continue;

                        list_add_tail(&entry->list, &ima_policy_rules);
                }
                if (entries[i].action == APPRAISE) {
                        if (entries != build_appraise_rules)
                                temp_ima_appraise |=
                                        ima_appraise_flag(entries[i].func);
                        else
                                build_ima_appraise |=
                                        ima_appraise_flag(entries[i].func);
                }
        }
}

static int ima_parse_rule(char *rule, struct ima_rule_entry *entry);

static int __init ima_init_arch_policy(void)
{
        const char * const *arch_rules;
        const char * const *rules;
        int arch_entries = 0;
        int i = 0;

        arch_rules = arch_get_ima_policy();
        if (!arch_rules)
                return arch_entries;

        /* Get number of rules */
        for (rules = arch_rules; *rules != NULL; rules++)
                arch_entries++;

        arch_policy_entry = kcalloc(arch_entries + 1,
                                    sizeof(*arch_policy_entry), GFP_KERNEL);
        if (!arch_policy_entry)
                return 0;

        /* Convert each policy string rules to struct ima_rule_entry format */
        for (rules = arch_rules, i = 0; *rules != NULL; rules++) {
                char rule[255];
                int result;

                result = strlcpy(rule, *rules, sizeof(rule));

                INIT_LIST_HEAD(&arch_policy_entry[i].list);
                result = ima_parse_rule(rule, &arch_policy_entry[i]);
                if (result) {
                        pr_warn("Skipping unknown architecture policy rule: %s\n",
                                rule);
                        memset(&arch_policy_entry[i], 0,
                               sizeof(*arch_policy_entry));
                        continue;
                }
                i++;
        }
        return i;
}

/**
 * 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 build_appraise_entries, arch_entries;

        /* if !ima_policy, we load NO default rules */
        if (ima_policy)
                add_rules(dont_measure_rules, ARRAY_SIZE(dont_measure_rules),
                          IMA_DEFAULT_POLICY);

        switch (ima_policy) {
        case ORIGINAL_TCB:
                add_rules(original_measurement_rules,
                          ARRAY_SIZE(original_measurement_rules),
                          IMA_DEFAULT_POLICY);
                break;
        case DEFAULT_TCB:
                add_rules(default_measurement_rules,
                          ARRAY_SIZE(default_measurement_rules),
                          IMA_DEFAULT_POLICY);
                break;
        default:
                break;
        }

        /*
         * Based on runtime secure boot flags, insert arch specific measurement
         * and appraise rules requiring file signatures for both the initial
         * and custom policies, prior to other appraise rules.
         * (Highest priority)
         */
        arch_entries = ima_init_arch_policy();
        if (!arch_entries)
                pr_info("No architecture policies found\n");
        else
                add_rules(arch_policy_entry, arch_entries,
                          IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);

        /*
         * Insert the builtin "secure_boot" policy rules requiring file
         * signatures, prior to other appraise rules.
         */
        if (ima_use_secure_boot)
                add_rules(secure_boot_rules, ARRAY_SIZE(secure_boot_rules),
                          IMA_DEFAULT_POLICY);

        /*
         * Insert the build time appraise rules requiring file signatures
         * for both the initial and custom policies, prior to other appraise
         * rules. As the secure boot rules includes all of the build time
         * rules, include either one or the other set of rules, but not both.
         */
        build_appraise_entries = ARRAY_SIZE(build_appraise_rules);
        if (build_appraise_entries) {
                if (ima_use_secure_boot)
                        add_rules(build_appraise_rules, build_appraise_entries,
                                  IMA_CUSTOM_POLICY);
                else
                        add_rules(build_appraise_rules, build_appraise_entries,
                                  IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
        }

        if (ima_use_appraise_tcb)
                add_rules(default_appraise_rules,
                          ARRAY_SIZE(default_appraise_rules),
                          IMA_DEFAULT_POLICY);

        if (ima_use_critical_data)
                add_rules(critical_data_rules,
                          ARRAY_SIZE(critical_data_rules),
                          IMA_DEFAULT_POLICY);

        atomic_set(&ima_setxattr_allowed_hash_algorithms, 0);

        ima_update_policy_flags();
}

/* 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 *policy = &ima_policy_rules;

        list_splice_tail_init_rcu(&ima_temp_rules, policy, synchronize_rcu);

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

                /*
                 * IMA architecture specific policy rules are specified
                 * as strings and converted to an array of ima_entry_rules
                 * on boot.  After loading a custom policy, free the
                 * architecture specific rules stored as an array.
                 */
                kfree(arch_policy_entry);
        }
        ima_update_policy_flags();

        /* Custom IMA policy has been loaded */
        ima_process_queued_keys();
}

/* Keep the enumeration in sync with the policy_tokens! */
enum {
        Opt_measure, Opt_dont_measure,
        Opt_appraise, Opt_dont_appraise,
        Opt_audit, Opt_hash, Opt_dont_hash,
        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_fsname,
        Opt_fsuuid, Opt_uid_eq, Opt_euid_eq, Opt_fowner_eq,
        Opt_uid_gt, Opt_euid_gt, Opt_fowner_gt,
        Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt,
        Opt_appraise_type, Opt_appraise_flag, Opt_appraise_algos,

        Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings,
        Opt_label, Opt_err
};

static const 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_hash, "hash"},
        {Opt_dont_hash, "dont_hash"},
        {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_fsname, "fsname=%s"},
        {Opt_fsuuid, "fsuuid=%s"},
        {Opt_uid_eq, "uid=%s"},
        {Opt_euid_eq, "euid=%s"},
        {Opt_fowner_eq, "fowner=%s"},
        {Opt_uid_gt, "uid>%s"},
        {Opt_euid_gt, "euid>%s"},
        {Opt_fowner_gt, "fowner>%s"},
        {Opt_uid_lt, "uid<%s"},
        {Opt_euid_lt, "euid<%s"},
        {Opt_fowner_lt, "fowner<%s"},
        {Opt_appraise_type, "appraise_type=%s"},
        {Opt_appraise_flag, "appraise_flag=%s"},
        {Opt_appraise_algos, "appraise_algos=%s"},
        {Opt_permit_directio, "permit_directio"},
        {Opt_pcr, "pcr=%s"},
        {Opt_template, "template=%s"},
        {Opt_keyrings, "keyrings=%s"},
        {Opt_label, "label=%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 = ima_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) {
                pr_warn("rule for LSM \'%s\' is undefined\n",
                        entry->lsm[lsm_rule].args_p);

                if (ima_rules == &ima_default_rules) {
                        kfree(entry->lsm[lsm_rule].args_p);
                        entry->lsm[lsm_rule].args_p = NULL;
                        result = -EINVAL;
                } else
                        result = 0;
        }

        return result;
}

static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
                              bool (*rule_operator)(kuid_t, kuid_t))
{
        if (!ab)
                return;

        if (rule_operator == &uid_gt)
                audit_log_format(ab, "%s>", key);
        else if (rule_operator == &uid_lt)
                audit_log_format(ab, "%s<", key);
        else
                audit_log_format(ab, "%s=", key);
        audit_log_format(ab, "%s ", value);
}
static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
{
        ima_log_string_op(ab, key, value, NULL);
}

/*
 * Validating the appended signature included in the measurement list requires
 * the file hash calculated without the appended signature (i.e., the 'd-modsig'
 * field). Therefore, notify the user if they have the 'modsig' field but not
 * the 'd-modsig' field in the template.
 */
static void check_template_modsig(const struct ima_template_desc *template)
{
#define MSG "template with 'modsig' field also needs 'd-modsig' field\n"
        bool has_modsig, has_dmodsig;
        static bool checked;
        int i;

        /* We only need to notify the user once. */
        if (checked)
                return;

        has_modsig = has_dmodsig = false;
        for (i = 0; i < template->num_fields; i++) {
                if (!strcmp(template->fields[i]->field_id, "modsig"))
                        has_modsig = true;
                else if (!strcmp(template->fields[i]->field_id, "d-modsig"))
                        has_dmodsig = true;
        }

        if (has_modsig && !has_dmodsig)
                pr_notice(MSG);

        checked = true;
#undef MSG
}

static bool ima_validate_rule(struct ima_rule_entry *entry)
{
        /* Ensure that the action is set and is compatible with the flags */
        if (entry->action == UNKNOWN)
                return false;

        if (entry->action != MEASURE && entry->flags & IMA_PCR)
                return false;

        if (entry->action != APPRAISE &&
            entry->flags & (IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED |
                            IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS))
                return false;

        /*
         * The IMA_FUNC bit must be set if and only if there's a valid hook
         * function specified, and vice versa. Enforcing this property allows
         * for the NONE case below to validate a rule without an explicit hook
         * function.
         */
        if (((entry->flags & IMA_FUNC) && entry->func == NONE) ||
            (!(entry->flags & IMA_FUNC) && entry->func != NONE))
                return false;

        /*
         * Ensure that the hook function is compatible with the other
         * components of the rule
         */
        switch (entry->func) {
        case NONE:
        case FILE_CHECK:
        case MMAP_CHECK:
        case BPRM_CHECK:
        case CREDS_CHECK:
        case POST_SETATTR:
        case FIRMWARE_CHECK:
        case POLICY_CHECK:
                if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
                                     IMA_UID | IMA_FOWNER | IMA_FSUUID |
                                     IMA_INMASK | IMA_EUID | IMA_PCR |
                                     IMA_FSNAME | IMA_DIGSIG_REQUIRED |
                                     IMA_PERMIT_DIRECTIO | IMA_VALIDATE_ALGOS))
                        return false;

                break;
        case MODULE_CHECK:
        case KEXEC_KERNEL_CHECK:
        case KEXEC_INITRAMFS_CHECK:
                if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
                                     IMA_UID | IMA_FOWNER | IMA_FSUUID |
                                     IMA_INMASK | IMA_EUID | IMA_PCR |
                                     IMA_FSNAME | IMA_DIGSIG_REQUIRED |
                                     IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED |
                                     IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS))
                        return false;

                break;
        case KEXEC_CMDLINE:
                if (entry->action & ~(MEASURE | DONT_MEASURE))
                        return false;

                if (entry->flags & ~(IMA_FUNC | IMA_FSMAGIC | IMA_UID |
                                     IMA_FOWNER | IMA_FSUUID | IMA_EUID |
                                     IMA_PCR | IMA_FSNAME))
                        return false;

                break;
        case KEY_CHECK:
                if (entry->action & ~(MEASURE | DONT_MEASURE))
                        return false;

                if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR |
                                     IMA_KEYRINGS))
                        return false;

                if (ima_rule_contains_lsm_cond(entry))
                        return false;

                break;
        case CRITICAL_DATA:
                if (entry->action & ~(MEASURE | DONT_MEASURE))
                        return false;

                if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR |
                                     IMA_LABEL))
                        return false;

                if (ima_rule_contains_lsm_cond(entry))
                        return false;

                break;
        case SETXATTR_CHECK:
                /* any action other than APPRAISE is unsupported */
                if (entry->action != APPRAISE)
                        return false;

                /* SETXATTR_CHECK requires an appraise_algos parameter */
                if (!(entry->flags & IMA_VALIDATE_ALGOS))
                        return false;

                /*
                 * full policies are not supported, they would have too
                 * much of a performance impact
                 */
                if (entry->flags & ~(IMA_FUNC | IMA_VALIDATE_ALGOS))
                        return false;

                break;
        default:
                return false;
        }

        /* Ensure that combinations of flags are compatible with each other */
        if (entry->flags & IMA_CHECK_BLACKLIST &&
            !(entry->flags & IMA_MODSIG_ALLOWED))
                return false;

        return true;
}

static unsigned int ima_parse_appraise_algos(char *arg)
{
        unsigned int res = 0;
        int idx;
        char *token;

        while ((token = strsep(&arg, ",")) != NULL) {
                idx = match_string(hash_algo_name, HASH_ALGO__LAST, token);

                if (idx < 0) {
                        pr_err("unknown hash algorithm \"%s\"",
                               token);
                        return 0;
                }

                if (!crypto_has_alg(hash_algo_name[idx], 0, 0)) {
                        pr_err("unavailable hash algorithm \"%s\", check your kernel configuration",
                               token);
                        return 0;
                }

                /* Add the hash algorithm to the 'allowed' bitfield */
                res |= (1U << idx);
        }

        return res;
}

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

        ab = integrity_audit_log_start(audit_context(), GFP_KERNEL,
                                       AUDIT_INTEGRITY_POLICY_RULE);

        entry->uid = INVALID_UID;
        entry->fowner = INVALID_UID;
        entry->uid_op = &uid_eq;
        entry->fowner_op = &uid_eq;
        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_hash:
                        ima_log_string(ab, "action", "hash");

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

                        entry->action = HASH;
                        break;
                case Opt_dont_hash:
                        ima_log_string(ab, "action", "dont_hash");

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

                        entry->action = DONT_HASH;
                        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, "CREDS_CHECK") == 0)
                                entry->func = CREDS_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 if (strcmp(args[0].from, "KEXEC_CMDLINE") == 0)
                                entry->func = KEXEC_CMDLINE;
                        else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) &&
                                 strcmp(args[0].from, "KEY_CHECK") == 0)
                                entry->func = KEY_CHECK;
                        else if (strcmp(args[0].from, "CRITICAL_DATA") == 0)
                                entry->func = CRITICAL_DATA;
                        else if (strcmp(args[0].from, "SETXATTR_CHECK") == 0)
                                entry->func = SETXATTR_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_fsname:
                        ima_log_string(ab, "fsname", args[0].from);

                        entry->fsname = kstrdup(args[0].from, GFP_KERNEL);
                        if (!entry->fsname) {
                                result = -ENOMEM;
                                break;
                        }
                        result = 0;
                        entry->flags |= IMA_FSNAME;
                        break;
                case Opt_keyrings:
                        ima_log_string(ab, "keyrings", args[0].from);

                        if (!IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) ||
                            entry->keyrings) {
                                result = -EINVAL;
                                break;
                        }

                        entry->keyrings = ima_alloc_rule_opt_list(args);
                        if (IS_ERR(entry->keyrings)) {
                                result = PTR_ERR(entry->keyrings);
                                entry->keyrings = NULL;
                                break;
                        }

                        entry->flags |= IMA_KEYRINGS;
                        break;
                case Opt_label:
                        ima_log_string(ab, "label", args[0].from);

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

                        entry->label = ima_alloc_rule_opt_list(args);
                        if (IS_ERR(entry->label)) {
                                result = PTR_ERR(entry->label);
                                entry->label = NULL;
                                break;
                        }

                        entry->flags |= IMA_LABEL;
                        break;
                case Opt_fsuuid:
                        ima_log_string(ab, "fsuuid", args[0].from);

                        if (!uuid_is_null(&entry->fsuuid)) {
                                result = -EINVAL;
                                break;
                        }

                        result = uuid_parse(args[0].from, &entry->fsuuid);
                        if (!result)
                                entry->flags |= IMA_FSUUID;
                        break;
                case Opt_uid_gt:
                case Opt_euid_gt:
                        entry->uid_op = &uid_gt;
                        fallthrough;
                case Opt_uid_lt:
                case Opt_euid_lt:
                        if ((token == Opt_uid_lt) || (token == Opt_euid_lt))
                                entry->uid_op = &uid_lt;
                        fallthrough;
                case Opt_uid_eq:
                case Opt_euid_eq:
                        uid_token = (token == Opt_uid_eq) ||
                                    (token == Opt_uid_gt) ||
                                    (token == Opt_uid_lt);

                        ima_log_string_op(ab, uid_token ? "uid" : "euid",
                                          args[0].from, entry->uid_op);

                        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 |= uid_token
                                            ? IMA_UID : IMA_EUID;
                        }
                        break;
                case Opt_fowner_gt:
                        entry->fowner_op = &uid_gt;
                        fallthrough;
                case Opt_fowner_lt:
                        if (token == Opt_fowner_lt)
                                entry->fowner_op = &uid_lt;
                        fallthrough;
                case Opt_fowner_eq:
                        ima_log_string_op(ab, "fowner", args[0].from,
                                          entry->fowner_op);

                        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:
                        ima_log_string(ab, "appraise_type", args[0].from);
                        if ((strcmp(args[0].from, "imasig")) == 0)
                                entry->flags |= IMA_DIGSIG_REQUIRED;
                        else if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
                                 strcmp(args[0].from, "imasig|modsig") == 0)
                                entry->flags |= IMA_DIGSIG_REQUIRED |
                                                IMA_MODSIG_ALLOWED;
                        else
                                result = -EINVAL;
                        break;
                case Opt_appraise_flag:
                        ima_log_string(ab, "appraise_flag", args[0].from);
                        if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
                            strstr(args[0].from, "blacklist"))
                                entry->flags |= IMA_CHECK_BLACKLIST;
                        else
                                result = -EINVAL;
                        break;
                case Opt_appraise_algos:
                        ima_log_string(ab, "appraise_algos", args[0].from);

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

                        entry->allowed_algos =
                                ima_parse_appraise_algos(args[0].from);
                        /* invalid or empty list of algorithms */
                        if (!entry->allowed_algos) {
                                result = -EINVAL;
                                break;
                        }

                        entry->flags |= IMA_VALIDATE_ALGOS;

                        break;
                case Opt_permit_directio:
                        entry->flags |= IMA_PERMIT_DIRECTIO;
                        break;
                case Opt_pcr:
                        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_template:
                        ima_log_string(ab, "template", args[0].from);
                        if (entry->action != MEASURE) {
                                result = -EINVAL;
                                break;
                        }
                        template_desc = lookup_template_desc(args[0].from);
                        if (!template_desc || entry->template) {
                                result = -EINVAL;
                                break;
                        }

                        /*
                         * template_desc_init_fields() does nothing if
                         * the template is already initialised, so
                         * it's safe to do this unconditionally
                         */
                        template_desc_init_fields(template_desc->fmt,
                                                 &(template_desc->fields),
                                                 &(template_desc->num_fields));
                        entry->template = template_desc;
                        break;
                case Opt_err:
                        ima_log_string(ab, "UNKNOWN", p);
                        result = -EINVAL;
                        break;
                }
        }
        if (!result && !ima_validate_rule(entry))
                result = -EINVAL;
        else if (entry->action == APPRAISE)
                temp_ima_appraise |= ima_appraise_flag(entry->func);

        if (!result && entry->flags & IMA_MODSIG_ALLOWED) {
                template_desc = entry->template ? entry->template :
                                                  ima_template_desc_current();
                check_template_modsig(template_desc);
        }

        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) {
                ima_free_rule(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;

        temp_ima_appraise = 0;
        list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
                list_del(&entry->list);
                ima_free_rule(entry);
        }
}

#define __ima_hook_stringify(func, str) (#func),

const char *const func_tokens[] = {
        __ima_hooks(__ima_hook_stringify)
};

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

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

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].pattern
#define mt(token)       mask_tokens[token]

/*
 * policy_func_show - display the ima_hooks policy rule
 */
static void policy_func_show(struct seq_file *m, enum ima_hooks func)
{
        if (func > 0 && func < MAX_CHECK)
                seq_printf(m, "func=%s ", func_tokens[func]);
        else
                seq_printf(m, "func=%d ", func);
}

static void ima_show_rule_opt_list(struct seq_file *m,
                                   const struct ima_rule_opt_list *opt_list)
{
        size_t i;

        for (i = 0; i < opt_list->count; i++)
                seq_printf(m, "%s%s", i ? "|" : "", opt_list->items[i]);
}

static void ima_policy_show_appraise_algos(struct seq_file *m,
                                           unsigned int allowed_hashes)
{
        int idx, list_size = 0;

        for (idx = 0; idx < HASH_ALGO__LAST; idx++) {
                if (!(allowed_hashes & (1U << idx)))
                        continue;

                /* only add commas if the list contains multiple entries */
                if (list_size++)
                        seq_puts(m, ",");

                seq_puts(m, hash_algo_name[idx]);
        }
}

int ima_policy_show(struct seq_file *m, void *v)
{
        struct ima_rule_entry *entry = v;
        int i;
        char tbuf[64] = {0,};
        int offset = 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));
        if (entry->action & HASH)
                seq_puts(m, pt(Opt_hash));
        if (entry->action & DONT_HASH)
                seq_puts(m, pt(Opt_dont_hash));

        seq_puts(m, " ");

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

        if ((entry->flags & IMA_MASK) || (entry->flags & IMA_INMASK)) {
                if (entry->flags & IMA_MASK)
                        offset = 1;
                if (entry->mask & MAY_EXEC)
                        seq_printf(m, pt(Opt_mask), mt(mask_exec) + offset);
                if (entry->mask & MAY_WRITE)
                        seq_printf(m, pt(Opt_mask), mt(mask_write) + offset);
                if (entry->mask & MAY_READ)
                        seq_printf(m, pt(Opt_mask), mt(mask_read) + offset);
                if (entry->mask & MAY_APPEND)
                        seq_printf(m, pt(Opt_mask), mt(mask_append) + offset);
                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_FSNAME) {
                snprintf(tbuf, sizeof(tbuf), "%s", entry->fsname);
                seq_printf(m, pt(Opt_fsname), tbuf);
                seq_puts(m, " ");
        }

        if (entry->flags & IMA_KEYRINGS) {
                seq_puts(m, "keyrings=");
                ima_show_rule_opt_list(m, entry->keyrings);
                seq_puts(m, " ");
        }

        if (entry->flags & IMA_LABEL) {
                seq_puts(m, "label=");
                ima_show_rule_opt_list(m, entry->label);
                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));
                if (entry->uid_op == &uid_gt)
                        seq_printf(m, pt(Opt_uid_gt), tbuf);
                else if (entry->uid_op == &uid_lt)
                        seq_printf(m, pt(Opt_uid_lt), tbuf);
                else
                        seq_printf(m, pt(Opt_uid_eq), tbuf);
                seq_puts(m, " ");
        }

        if (entry->flags & IMA_EUID) {
                snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
                if (entry->uid_op == &uid_gt)
                        seq_printf(m, pt(Opt_euid_gt), tbuf);
                else if (entry->uid_op == &uid_lt)
                        seq_printf(m, pt(Opt_euid_lt), tbuf);
                else
                        seq_printf(m, pt(Opt_euid_eq), tbuf);
                seq_puts(m, " ");
        }

        if (entry->flags & IMA_FOWNER) {
                snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner));
                if (entry->fowner_op == &uid_gt)
                        seq_printf(m, pt(Opt_fowner_gt), tbuf);
                else if (entry->fowner_op == &uid_lt)
                        seq_printf(m, pt(Opt_fowner_lt), tbuf);
                else
                        seq_printf(m, pt(Opt_fowner_eq), tbuf);
                seq_puts(m, " ");
        }

        if (entry->flags & IMA_VALIDATE_ALGOS) {
                seq_puts(m, "appraise_algos=");
                ima_policy_show_appraise_algos(m, entry->allowed_algos);
                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),
                                           entry->lsm[i].args_p);
                                break;
                        case LSM_OBJ_ROLE:
                                seq_printf(m, pt(Opt_obj_role),
                                           entry->lsm[i].args_p);
                                break;
                        case LSM_OBJ_TYPE:
                                seq_printf(m, pt(Opt_obj_type),
                                           entry->lsm[i].args_p);
                                break;
                        case LSM_SUBJ_USER:
                                seq_printf(m, pt(Opt_subj_user),
                                           entry->lsm[i].args_p);
                                break;
                        case LSM_SUBJ_ROLE:
                                seq_printf(m, pt(Opt_subj_role),
                                           entry->lsm[i].args_p);
                                break;
                        case LSM_SUBJ_TYPE:
                                seq_printf(m, pt(Opt_subj_type),
                                           entry->lsm[i].args_p);
                                break;
                        }
                        seq_puts(m, " ");
                }
        }
        if (entry->template)
                seq_printf(m, "template=%s ", entry->template->name);
        if (entry->flags & IMA_DIGSIG_REQUIRED) {
                if (entry->flags & IMA_MODSIG_ALLOWED)
                        seq_puts(m, "appraise_type=imasig|modsig ");
                else
                        seq_puts(m, "appraise_type=imasig ");
        }
        if (entry->flags & IMA_CHECK_BLACKLIST)
                seq_puts(m, "appraise_flag=check_blacklist ");
        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 */

#if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
/*
 * ima_appraise_signature: whether IMA will appraise a given function using
 * an IMA digital signature. This is restricted to cases where the kernel
 * has a set of built-in trusted keys in order to avoid an attacker simply
 * loading additional keys.
 */
bool ima_appraise_signature(enum kernel_read_file_id id)
{
        struct ima_rule_entry *entry;
        bool found = false;
        enum ima_hooks func;

        if (id >= READING_MAX_ID)
                return false;

        func = read_idmap[id] ?: FILE_CHECK;

        rcu_read_lock();
        list_for_each_entry_rcu(entry, ima_rules, list) {
                if (entry->action != APPRAISE)
                        continue;

                /*
                 * A generic entry will match, but otherwise require that it
                 * match the func we're looking for
                 */
                if (entry->func && entry->func != func)
                        continue;

                /*
                 * We require this to be a digital signature, not a raw IMA
                 * hash.
                 */
                if (entry->flags & IMA_DIGSIG_REQUIRED)
                        found = true;

                /*
                 * We've found a rule that matches, so break now even if it
                 * didn't require a digital signature - a later rule that does
                 * won't override it, so would be a false positive.
                 */
                break;
        }

        rcu_read_unlock();
        return found;
}
#endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */