Merge tag 'nfsd-5.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux

[mirror_ubuntu-jammy-kernel.git] / security / tomoyo / file.c

// SPDX-License-Identifier: GPL-2.0
/*
 * security/tomoyo/file.c
 *
 * Copyright (C) 2005-2011  NTT DATA CORPORATION
 */

#include "common.h"
#include <linux/slab.h>

/*
 * Mapping table from "enum tomoyo_path_acl_index" to "enum tomoyo_mac_index".
 */
static const u8 tomoyo_p2mac[TOMOYO_MAX_PATH_OPERATION] = {
        [TOMOYO_TYPE_EXECUTE]    = TOMOYO_MAC_FILE_EXECUTE,
        [TOMOYO_TYPE_READ]       = TOMOYO_MAC_FILE_OPEN,
        [TOMOYO_TYPE_WRITE]      = TOMOYO_MAC_FILE_OPEN,
        [TOMOYO_TYPE_APPEND]     = TOMOYO_MAC_FILE_OPEN,
        [TOMOYO_TYPE_UNLINK]     = TOMOYO_MAC_FILE_UNLINK,
        [TOMOYO_TYPE_GETATTR]    = TOMOYO_MAC_FILE_GETATTR,
        [TOMOYO_TYPE_RMDIR]      = TOMOYO_MAC_FILE_RMDIR,
        [TOMOYO_TYPE_TRUNCATE]   = TOMOYO_MAC_FILE_TRUNCATE,
        [TOMOYO_TYPE_SYMLINK]    = TOMOYO_MAC_FILE_SYMLINK,
        [TOMOYO_TYPE_CHROOT]     = TOMOYO_MAC_FILE_CHROOT,
        [TOMOYO_TYPE_UMOUNT]     = TOMOYO_MAC_FILE_UMOUNT,
};

/*
 * Mapping table from "enum tomoyo_mkdev_acl_index" to "enum tomoyo_mac_index".
 */
const u8 tomoyo_pnnn2mac[TOMOYO_MAX_MKDEV_OPERATION] = {
        [TOMOYO_TYPE_MKBLOCK] = TOMOYO_MAC_FILE_MKBLOCK,
        [TOMOYO_TYPE_MKCHAR]  = TOMOYO_MAC_FILE_MKCHAR,
};

/*
 * Mapping table from "enum tomoyo_path2_acl_index" to "enum tomoyo_mac_index".
 */
const u8 tomoyo_pp2mac[TOMOYO_MAX_PATH2_OPERATION] = {
        [TOMOYO_TYPE_LINK]       = TOMOYO_MAC_FILE_LINK,
        [TOMOYO_TYPE_RENAME]     = TOMOYO_MAC_FILE_RENAME,
        [TOMOYO_TYPE_PIVOT_ROOT] = TOMOYO_MAC_FILE_PIVOT_ROOT,
};

/*
 * Mapping table from "enum tomoyo_path_number_acl_index" to
 * "enum tomoyo_mac_index".
 */
const u8 tomoyo_pn2mac[TOMOYO_MAX_PATH_NUMBER_OPERATION] = {
        [TOMOYO_TYPE_CREATE] = TOMOYO_MAC_FILE_CREATE,
        [TOMOYO_TYPE_MKDIR]  = TOMOYO_MAC_FILE_MKDIR,
        [TOMOYO_TYPE_MKFIFO] = TOMOYO_MAC_FILE_MKFIFO,
        [TOMOYO_TYPE_MKSOCK] = TOMOYO_MAC_FILE_MKSOCK,
        [TOMOYO_TYPE_IOCTL]  = TOMOYO_MAC_FILE_IOCTL,
        [TOMOYO_TYPE_CHMOD]  = TOMOYO_MAC_FILE_CHMOD,
        [TOMOYO_TYPE_CHOWN]  = TOMOYO_MAC_FILE_CHOWN,
        [TOMOYO_TYPE_CHGRP]  = TOMOYO_MAC_FILE_CHGRP,
};

/**
 * tomoyo_put_name_union - Drop reference on "struct tomoyo_name_union".
 *
 * @ptr: Pointer to "struct tomoyo_name_union".
 *
 * Returns nothing.
 */
void tomoyo_put_name_union(struct tomoyo_name_union *ptr)
{
        tomoyo_put_group(ptr->group);
        tomoyo_put_name(ptr->filename);
}

/**
 * tomoyo_compare_name_union - Check whether a name matches "struct tomoyo_name_union" or not.
 *
 * @name: Pointer to "struct tomoyo_path_info".
 * @ptr:  Pointer to "struct tomoyo_name_union".
 *
 * Returns "struct tomoyo_path_info" if @name matches @ptr, NULL otherwise.
 */
const struct tomoyo_path_info *
tomoyo_compare_name_union(const struct tomoyo_path_info *name,
                          const struct tomoyo_name_union *ptr)
{
        if (ptr->group)
                return tomoyo_path_matches_group(name, ptr->group);
        if (tomoyo_path_matches_pattern(name, ptr->filename))
                return ptr->filename;
        return NULL;
}

/**
 * tomoyo_put_number_union - Drop reference on "struct tomoyo_number_union".
 *
 * @ptr: Pointer to "struct tomoyo_number_union".
 *
 * Returns nothing.
 */
void tomoyo_put_number_union(struct tomoyo_number_union *ptr)
{
        tomoyo_put_group(ptr->group);
}

/**
 * tomoyo_compare_number_union - Check whether a value matches "struct tomoyo_number_union" or not.
 *
 * @value: Number to check.
 * @ptr:   Pointer to "struct tomoyo_number_union".
 *
 * Returns true if @value matches @ptr, false otherwise.
 */
bool tomoyo_compare_number_union(const unsigned long value,
                                 const struct tomoyo_number_union *ptr)
{
        if (ptr->group)
                return tomoyo_number_matches_group(value, value, ptr->group);
        return value >= ptr->values[0] && value <= ptr->values[1];
}

/**
 * tomoyo_add_slash - Add trailing '/' if needed.
 *
 * @buf: Pointer to "struct tomoyo_path_info".
 *
 * Returns nothing.
 *
 * @buf must be generated by tomoyo_encode() because this function does not
 * allocate memory for adding '/'.
 */
static void tomoyo_add_slash(struct tomoyo_path_info *buf)
{
        if (buf->is_dir)
                return;
        /*
         * This is OK because tomoyo_encode() reserves space for appending "/".
         */
        strcat((char *) buf->name, "/");
        tomoyo_fill_path_info(buf);
}

/**
 * tomoyo_get_realpath - Get realpath.
 *
 * @buf:  Pointer to "struct tomoyo_path_info".
 * @path: Pointer to "struct path".
 *
 * Returns true on success, false otherwise.
 */
static bool tomoyo_get_realpath(struct tomoyo_path_info *buf, const struct path *path)
{
        buf->name = tomoyo_realpath_from_path(path);
        if (buf->name) {
                tomoyo_fill_path_info(buf);
                return true;
        }
        return false;
}

/**
 * tomoyo_audit_path_log - Audit path request log.
 *
 * @r: Pointer to "struct tomoyo_request_info".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_audit_path_log(struct tomoyo_request_info *r)
{
        return tomoyo_supervisor(r, "file %s %s\n", tomoyo_path_keyword
                                 [r->param.path.operation],
                                 r->param.path.filename->name);
}

/**
 * tomoyo_audit_path2_log - Audit path/path request log.
 *
 * @r: Pointer to "struct tomoyo_request_info".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_audit_path2_log(struct tomoyo_request_info *r)
{
        return tomoyo_supervisor(r, "file %s %s %s\n", tomoyo_mac_keywords
                                 [tomoyo_pp2mac[r->param.path2.operation]],
                                 r->param.path2.filename1->name,
                                 r->param.path2.filename2->name);
}

/**
 * tomoyo_audit_mkdev_log - Audit path/number/number/number request log.
 *
 * @r: Pointer to "struct tomoyo_request_info".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_audit_mkdev_log(struct tomoyo_request_info *r)
{
        return tomoyo_supervisor(r, "file %s %s 0%o %u %u\n",
                                 tomoyo_mac_keywords
                                 [tomoyo_pnnn2mac[r->param.mkdev.operation]],
                                 r->param.mkdev.filename->name,
                                 r->param.mkdev.mode, r->param.mkdev.major,
                                 r->param.mkdev.minor);
}

/**
 * tomoyo_audit_path_number_log - Audit path/number request log.
 *
 * @r: Pointer to "struct tomoyo_request_info".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_audit_path_number_log(struct tomoyo_request_info *r)
{
        const u8 type = r->param.path_number.operation;
        u8 radix;
        char buffer[64];

        switch (type) {
        case TOMOYO_TYPE_CREATE:
        case TOMOYO_TYPE_MKDIR:
        case TOMOYO_TYPE_MKFIFO:
        case TOMOYO_TYPE_MKSOCK:
        case TOMOYO_TYPE_CHMOD:
                radix = TOMOYO_VALUE_TYPE_OCTAL;
                break;
        case TOMOYO_TYPE_IOCTL:
                radix = TOMOYO_VALUE_TYPE_HEXADECIMAL;
                break;
        default:
                radix = TOMOYO_VALUE_TYPE_DECIMAL;
                break;
        }
        tomoyo_print_ulong(buffer, sizeof(buffer), r->param.path_number.number,
                           radix);
        return tomoyo_supervisor(r, "file %s %s %s\n", tomoyo_mac_keywords
                                 [tomoyo_pn2mac[type]],
                                 r->param.path_number.filename->name, buffer);
}

/**
 * tomoyo_check_path_acl - Check permission for path operation.
 *
 * @r:   Pointer to "struct tomoyo_request_info".
 * @ptr: Pointer to "struct tomoyo_acl_info".
 *
 * Returns true if granted, false otherwise.
 *
 * To be able to use wildcard for domain transition, this function sets
 * matching entry on success. Since the caller holds tomoyo_read_lock(),
 * it is safe to set matching entry.
 */
static bool tomoyo_check_path_acl(struct tomoyo_request_info *r,
                                  const struct tomoyo_acl_info *ptr)
{
        const struct tomoyo_path_acl *acl = container_of(ptr, typeof(*acl),
                                                         head);

        if (acl->perm & (1 << r->param.path.operation)) {
                r->param.path.matched_path =
                        tomoyo_compare_name_union(r->param.path.filename,
                                                  &acl->name);
                return r->param.path.matched_path != NULL;
        }
        return false;
}

/**
 * tomoyo_check_path_number_acl - Check permission for path number operation.
 *
 * @r:   Pointer to "struct tomoyo_request_info".
 * @ptr: Pointer to "struct tomoyo_acl_info".
 *
 * Returns true if granted, false otherwise.
 */
static bool tomoyo_check_path_number_acl(struct tomoyo_request_info *r,
                                         const struct tomoyo_acl_info *ptr)
{
        const struct tomoyo_path_number_acl *acl =
                container_of(ptr, typeof(*acl), head);

        return (acl->perm & (1 << r->param.path_number.operation)) &&
                tomoyo_compare_number_union(r->param.path_number.number,
                                            &acl->number) &&
                tomoyo_compare_name_union(r->param.path_number.filename,
                                          &acl->name);
}

/**
 * tomoyo_check_path2_acl - Check permission for path path operation.
 *
 * @r:   Pointer to "struct tomoyo_request_info".
 * @ptr: Pointer to "struct tomoyo_acl_info".
 *
 * Returns true if granted, false otherwise.
 */
static bool tomoyo_check_path2_acl(struct tomoyo_request_info *r,
                                   const struct tomoyo_acl_info *ptr)
{
        const struct tomoyo_path2_acl *acl =
                container_of(ptr, typeof(*acl), head);

        return (acl->perm & (1 << r->param.path2.operation)) &&
                tomoyo_compare_name_union(r->param.path2.filename1, &acl->name1)
                && tomoyo_compare_name_union(r->param.path2.filename2,
                                             &acl->name2);
}

/**
 * tomoyo_check_mkdev_acl - Check permission for path number number number operation.
 *
 * @r:   Pointer to "struct tomoyo_request_info".
 * @ptr: Pointer to "struct tomoyo_acl_info".
 *
 * Returns true if granted, false otherwise.
 */
static bool tomoyo_check_mkdev_acl(struct tomoyo_request_info *r,
                                   const struct tomoyo_acl_info *ptr)
{
        const struct tomoyo_mkdev_acl *acl =
                container_of(ptr, typeof(*acl), head);

        return (acl->perm & (1 << r->param.mkdev.operation)) &&
                tomoyo_compare_number_union(r->param.mkdev.mode,
                                            &acl->mode) &&
                tomoyo_compare_number_union(r->param.mkdev.major,
                                            &acl->major) &&
                tomoyo_compare_number_union(r->param.mkdev.minor,
                                            &acl->minor) &&
                tomoyo_compare_name_union(r->param.mkdev.filename,
                                          &acl->name);
}

/**
 * tomoyo_same_path_acl - Check for duplicated "struct tomoyo_path_acl" entry.
 *
 * @a: Pointer to "struct tomoyo_acl_info".
 * @b: Pointer to "struct tomoyo_acl_info".
 *
 * Returns true if @a == @b except permission bits, false otherwise.
 */
static bool tomoyo_same_path_acl(const struct tomoyo_acl_info *a,
                                 const struct tomoyo_acl_info *b)
{
        const struct tomoyo_path_acl *p1 = container_of(a, typeof(*p1), head);
        const struct tomoyo_path_acl *p2 = container_of(b, typeof(*p2), head);

        return tomoyo_same_name_union(&p1->name, &p2->name);
}

/**
 * tomoyo_merge_path_acl - Merge duplicated "struct tomoyo_path_acl" entry.
 *
 * @a:         Pointer to "struct tomoyo_acl_info".
 * @b:         Pointer to "struct tomoyo_acl_info".
 * @is_delete: True for @a &= ~@b, false for @a |= @b.
 *
 * Returns true if @a is empty, false otherwise.
 */
static bool tomoyo_merge_path_acl(struct tomoyo_acl_info *a,
                                  struct tomoyo_acl_info *b,
                                  const bool is_delete)
{
        u16 * const a_perm = &container_of(a, struct tomoyo_path_acl, head)
                ->perm;
        u16 perm = READ_ONCE(*a_perm);
        const u16 b_perm = container_of(b, struct tomoyo_path_acl, head)->perm;

        if (is_delete)
                perm &= ~b_perm;
        else
                perm |= b_perm;
        WRITE_ONCE(*a_perm, perm);
        return !perm;
}

/**
 * tomoyo_update_path_acl - Update "struct tomoyo_path_acl" list.
 *
 * @perm:  Permission.
 * @param: Pointer to "struct tomoyo_acl_param".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_update_path_acl(const u16 perm,
                                  struct tomoyo_acl_param *param)
{
        struct tomoyo_path_acl e = {
                .head.type = TOMOYO_TYPE_PATH_ACL,
                .perm = perm
        };
        int error;

        if (!tomoyo_parse_name_union(param, &e.name))
                error = -EINVAL;
        else
                error = tomoyo_update_domain(&e.head, sizeof(e), param,
                                             tomoyo_same_path_acl,
                                             tomoyo_merge_path_acl);
        tomoyo_put_name_union(&e.name);
        return error;
}

/**
 * tomoyo_same_mkdev_acl - Check for duplicated "struct tomoyo_mkdev_acl" entry.
 *
 * @a: Pointer to "struct tomoyo_acl_info".
 * @b: Pointer to "struct tomoyo_acl_info".
 *
 * Returns true if @a == @b except permission bits, false otherwise.
 */
static bool tomoyo_same_mkdev_acl(const struct tomoyo_acl_info *a,
                                         const struct tomoyo_acl_info *b)
{
        const struct tomoyo_mkdev_acl *p1 = container_of(a, typeof(*p1), head);
        const struct tomoyo_mkdev_acl *p2 = container_of(b, typeof(*p2), head);

        return tomoyo_same_name_union(&p1->name, &p2->name) &&
                tomoyo_same_number_union(&p1->mode, &p2->mode) &&
                tomoyo_same_number_union(&p1->major, &p2->major) &&
                tomoyo_same_number_union(&p1->minor, &p2->minor);
}

/**
 * tomoyo_merge_mkdev_acl - Merge duplicated "struct tomoyo_mkdev_acl" entry.
 *
 * @a:         Pointer to "struct tomoyo_acl_info".
 * @b:         Pointer to "struct tomoyo_acl_info".
 * @is_delete: True for @a &= ~@b, false for @a |= @b.
 *
 * Returns true if @a is empty, false otherwise.
 */
static bool tomoyo_merge_mkdev_acl(struct tomoyo_acl_info *a,
                                   struct tomoyo_acl_info *b,
                                   const bool is_delete)
{
        u8 *const a_perm = &container_of(a, struct tomoyo_mkdev_acl,
                                         head)->perm;
        u8 perm = READ_ONCE(*a_perm);
        const u8 b_perm = container_of(b, struct tomoyo_mkdev_acl, head)
                ->perm;

        if (is_delete)
                perm &= ~b_perm;
        else
                perm |= b_perm;
        WRITE_ONCE(*a_perm, perm);
        return !perm;
}

/**
 * tomoyo_update_mkdev_acl - Update "struct tomoyo_mkdev_acl" list.
 *
 * @perm:  Permission.
 * @param: Pointer to "struct tomoyo_acl_param".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_update_mkdev_acl(const u8 perm,
                                   struct tomoyo_acl_param *param)
{
        struct tomoyo_mkdev_acl e = {
                .head.type = TOMOYO_TYPE_MKDEV_ACL,
                .perm = perm
        };
        int error;

        if (!tomoyo_parse_name_union(param, &e.name) ||
            !tomoyo_parse_number_union(param, &e.mode) ||
            !tomoyo_parse_number_union(param, &e.major) ||
            !tomoyo_parse_number_union(param, &e.minor))
                error = -EINVAL;
        else
                error = tomoyo_update_domain(&e.head, sizeof(e), param,
                                             tomoyo_same_mkdev_acl,
                                             tomoyo_merge_mkdev_acl);
        tomoyo_put_name_union(&e.name);
        tomoyo_put_number_union(&e.mode);
        tomoyo_put_number_union(&e.major);
        tomoyo_put_number_union(&e.minor);
        return error;
}

/**
 * tomoyo_same_path2_acl - Check for duplicated "struct tomoyo_path2_acl" entry.
 *
 * @a: Pointer to "struct tomoyo_acl_info".
 * @b: Pointer to "struct tomoyo_acl_info".
 *
 * Returns true if @a == @b except permission bits, false otherwise.
 */
static bool tomoyo_same_path2_acl(const struct tomoyo_acl_info *a,
                                  const struct tomoyo_acl_info *b)
{
        const struct tomoyo_path2_acl *p1 = container_of(a, typeof(*p1), head);
        const struct tomoyo_path2_acl *p2 = container_of(b, typeof(*p2), head);

        return tomoyo_same_name_union(&p1->name1, &p2->name1) &&
                tomoyo_same_name_union(&p1->name2, &p2->name2);
}

/**
 * tomoyo_merge_path2_acl - Merge duplicated "struct tomoyo_path2_acl" entry.
 *
 * @a:         Pointer to "struct tomoyo_acl_info".
 * @b:         Pointer to "struct tomoyo_acl_info".
 * @is_delete: True for @a &= ~@b, false for @a |= @b.
 *
 * Returns true if @a is empty, false otherwise.
 */
static bool tomoyo_merge_path2_acl(struct tomoyo_acl_info *a,
                                   struct tomoyo_acl_info *b,
                                   const bool is_delete)
{
        u8 * const a_perm = &container_of(a, struct tomoyo_path2_acl, head)
                ->perm;
        u8 perm = READ_ONCE(*a_perm);
        const u8 b_perm = container_of(b, struct tomoyo_path2_acl, head)->perm;

        if (is_delete)
                perm &= ~b_perm;
        else
                perm |= b_perm;
        WRITE_ONCE(*a_perm, perm);
        return !perm;
}

/**
 * tomoyo_update_path2_acl - Update "struct tomoyo_path2_acl" list.
 *
 * @perm:  Permission.
 * @param: Pointer to "struct tomoyo_acl_param".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_update_path2_acl(const u8 perm,
                                   struct tomoyo_acl_param *param)
{
        struct tomoyo_path2_acl e = {
                .head.type = TOMOYO_TYPE_PATH2_ACL,
                .perm = perm
        };
        int error;

        if (!tomoyo_parse_name_union(param, &e.name1) ||
            !tomoyo_parse_name_union(param, &e.name2))
                error = -EINVAL;
        else
                error = tomoyo_update_domain(&e.head, sizeof(e), param,
                                             tomoyo_same_path2_acl,
                                             tomoyo_merge_path2_acl);
        tomoyo_put_name_union(&e.name1);
        tomoyo_put_name_union(&e.name2);
        return error;
}

/**
 * tomoyo_path_permission - Check permission for single path operation.
 *
 * @r:         Pointer to "struct tomoyo_request_info".
 * @operation: Type of operation.
 * @filename:  Filename to check.
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_path_permission(struct tomoyo_request_info *r, u8 operation,
                                  const struct tomoyo_path_info *filename)
{
        int error;

        r->type = tomoyo_p2mac[operation];
        r->mode = tomoyo_get_mode(r->domain->ns, r->profile, r->type);
        if (r->mode == TOMOYO_CONFIG_DISABLED)
                return 0;
        r->param_type = TOMOYO_TYPE_PATH_ACL;
        r->param.path.filename = filename;
        r->param.path.operation = operation;
        do {
                tomoyo_check_acl(r, tomoyo_check_path_acl);
                error = tomoyo_audit_path_log(r);
        } while (error == TOMOYO_RETRY_REQUEST);
        return error;
}

/**
 * tomoyo_execute_permission - Check permission for execute operation.
 *
 * @r:         Pointer to "struct tomoyo_request_info".
 * @filename:  Filename to check.
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
int tomoyo_execute_permission(struct tomoyo_request_info *r,
                              const struct tomoyo_path_info *filename)
{
        /*
         * Unlike other permission checks, this check is done regardless of
         * profile mode settings in order to check for domain transition
         * preference.
         */
        r->type = TOMOYO_MAC_FILE_EXECUTE;
        r->mode = tomoyo_get_mode(r->domain->ns, r->profile, r->type);
        r->param_type = TOMOYO_TYPE_PATH_ACL;
        r->param.path.filename = filename;
        r->param.path.operation = TOMOYO_TYPE_EXECUTE;
        tomoyo_check_acl(r, tomoyo_check_path_acl);
        r->ee->transition = r->matched_acl && r->matched_acl->cond ?
                r->matched_acl->cond->transit : NULL;
        if (r->mode != TOMOYO_CONFIG_DISABLED)
                return tomoyo_audit_path_log(r);
        return 0;
}

/**
 * tomoyo_same_path_number_acl - Check for duplicated "struct tomoyo_path_number_acl" entry.
 *
 * @a: Pointer to "struct tomoyo_acl_info".
 * @b: Pointer to "struct tomoyo_acl_info".
 *
 * Returns true if @a == @b except permission bits, false otherwise.
 */
static bool tomoyo_same_path_number_acl(const struct tomoyo_acl_info *a,
                                        const struct tomoyo_acl_info *b)
{
        const struct tomoyo_path_number_acl *p1 = container_of(a, typeof(*p1),
                                                               head);
        const struct tomoyo_path_number_acl *p2 = container_of(b, typeof(*p2),
                                                               head);

        return tomoyo_same_name_union(&p1->name, &p2->name) &&
                tomoyo_same_number_union(&p1->number, &p2->number);
}

/**
 * tomoyo_merge_path_number_acl - Merge duplicated "struct tomoyo_path_number_acl" entry.
 *
 * @a:         Pointer to "struct tomoyo_acl_info".
 * @b:         Pointer to "struct tomoyo_acl_info".
 * @is_delete: True for @a &= ~@b, false for @a |= @b.
 *
 * Returns true if @a is empty, false otherwise.
 */
static bool tomoyo_merge_path_number_acl(struct tomoyo_acl_info *a,
                                         struct tomoyo_acl_info *b,
                                         const bool is_delete)
{
        u8 * const a_perm = &container_of(a, struct tomoyo_path_number_acl,
                                          head)->perm;
        u8 perm = READ_ONCE(*a_perm);
        const u8 b_perm = container_of(b, struct tomoyo_path_number_acl, head)
                ->perm;

        if (is_delete)
                perm &= ~b_perm;
        else
                perm |= b_perm;
        WRITE_ONCE(*a_perm, perm);
        return !perm;
}

/**
 * tomoyo_update_path_number_acl - Update ioctl/chmod/chown/chgrp ACL.
 *
 * @perm:  Permission.
 * @param: Pointer to "struct tomoyo_acl_param".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_update_path_number_acl(const u8 perm,
                                         struct tomoyo_acl_param *param)
{
        struct tomoyo_path_number_acl e = {
                .head.type = TOMOYO_TYPE_PATH_NUMBER_ACL,
                .perm = perm
        };
        int error;

        if (!tomoyo_parse_name_union(param, &e.name) ||
            !tomoyo_parse_number_union(param, &e.number))
                error = -EINVAL;
        else
                error = tomoyo_update_domain(&e.head, sizeof(e), param,
                                             tomoyo_same_path_number_acl,
                                             tomoyo_merge_path_number_acl);
        tomoyo_put_name_union(&e.name);
        tomoyo_put_number_union(&e.number);
        return error;
}

/**
 * tomoyo_path_number_perm - Check permission for "create", "mkdir", "mkfifo", "mksock", "ioctl", "chmod", "chown", "chgrp".
 *
 * @type:   Type of operation.
 * @path:   Pointer to "struct path".
 * @number: Number.
 *
 * Returns 0 on success, negative value otherwise.
 */
int tomoyo_path_number_perm(const u8 type, const struct path *path,
                            unsigned long number)
{
        struct tomoyo_request_info r;
        struct tomoyo_obj_info obj = {
                .path1 = { .mnt = path->mnt, .dentry = path->dentry },
        };
        int error = -ENOMEM;
        struct tomoyo_path_info buf;
        int idx;

        if (tomoyo_init_request_info(&r, NULL, tomoyo_pn2mac[type])
            == TOMOYO_CONFIG_DISABLED || !path->dentry)
                return 0;
        idx = tomoyo_read_lock();
        if (!tomoyo_get_realpath(&buf, path))
                goto out;
        r.obj = &obj;
        if (type == TOMOYO_TYPE_MKDIR)
                tomoyo_add_slash(&buf);
        r.param_type = TOMOYO_TYPE_PATH_NUMBER_ACL;
        r.param.path_number.operation = type;
        r.param.path_number.filename = &buf;
        r.param.path_number.number = number;
        do {
                tomoyo_check_acl(&r, tomoyo_check_path_number_acl);
                error = tomoyo_audit_path_number_log(&r);
        } while (error == TOMOYO_RETRY_REQUEST);
        kfree(buf.name);
 out:
        tomoyo_read_unlock(idx);
        if (r.mode != TOMOYO_CONFIG_ENFORCING)
                error = 0;
        return error;
}

/**
 * tomoyo_check_open_permission - Check permission for "read" and "write".
 *
 * @domain: Pointer to "struct tomoyo_domain_info".
 * @path:   Pointer to "struct path".
 * @flag:   Flags for open().
 *
 * Returns 0 on success, negative value otherwise.
 */
int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
                                 const struct path *path, const int flag)
{
        const u8 acc_mode = ACC_MODE(flag);
        int error = 0;
        struct tomoyo_path_info buf;
        struct tomoyo_request_info r;
        struct tomoyo_obj_info obj = {
                .path1 = { .mnt = path->mnt, .dentry = path->dentry },
        };
        int idx;

        buf.name = NULL;
        r.mode = TOMOYO_CONFIG_DISABLED;
        idx = tomoyo_read_lock();
        if (acc_mode &&
            tomoyo_init_request_info(&r, domain, TOMOYO_MAC_FILE_OPEN)
            != TOMOYO_CONFIG_DISABLED) {
                if (!tomoyo_get_realpath(&buf, path)) {
                        error = -ENOMEM;
                        goto out;
                }
                r.obj = &obj;
                if (acc_mode & MAY_READ)
                        error = tomoyo_path_permission(&r, TOMOYO_TYPE_READ,
                                                       &buf);
                if (!error && (acc_mode & MAY_WRITE))
                        error = tomoyo_path_permission(&r, (flag & O_APPEND) ?
                                                       TOMOYO_TYPE_APPEND :
                                                       TOMOYO_TYPE_WRITE,
                                                       &buf);
        }
 out:
        kfree(buf.name);
        tomoyo_read_unlock(idx);
        if (r.mode != TOMOYO_CONFIG_ENFORCING)
                error = 0;
        return error;
}

/**
 * tomoyo_path_perm - Check permission for "unlink", "rmdir", "truncate", "symlink", "append", "chroot" and "unmount".
 *
 * @operation: Type of operation.
 * @path:      Pointer to "struct path".
 * @target:    Symlink's target if @operation is TOMOYO_TYPE_SYMLINK,
 *             NULL otherwise.
 *
 * Returns 0 on success, negative value otherwise.
 */
int tomoyo_path_perm(const u8 operation, const struct path *path, const char *target)
{
        struct tomoyo_request_info r;
        struct tomoyo_obj_info obj = {
                .path1 = { .mnt = path->mnt, .dentry = path->dentry },
        };
        int error;
        struct tomoyo_path_info buf;
        bool is_enforce;
        struct tomoyo_path_info symlink_target;
        int idx;

        if (tomoyo_init_request_info(&r, NULL, tomoyo_p2mac[operation])
            == TOMOYO_CONFIG_DISABLED)
                return 0;
        is_enforce = (r.mode == TOMOYO_CONFIG_ENFORCING);
        error = -ENOMEM;
        buf.name = NULL;
        idx = tomoyo_read_lock();
        if (!tomoyo_get_realpath(&buf, path))
                goto out;
        r.obj = &obj;
        switch (operation) {
        case TOMOYO_TYPE_RMDIR:
        case TOMOYO_TYPE_CHROOT:
                tomoyo_add_slash(&buf);
                break;
        case TOMOYO_TYPE_SYMLINK:
                symlink_target.name = tomoyo_encode(target);
                if (!symlink_target.name)
                        goto out;
                tomoyo_fill_path_info(&symlink_target);
                obj.symlink_target = &symlink_target;
                break;
        }
        error = tomoyo_path_permission(&r, operation, &buf);
        if (operation == TOMOYO_TYPE_SYMLINK)
                kfree(symlink_target.name);
 out:
        kfree(buf.name);
        tomoyo_read_unlock(idx);
        if (!is_enforce)
                error = 0;
        return error;
}

/**
 * tomoyo_mkdev_perm - Check permission for "mkblock" and "mkchar".
 *
 * @operation: Type of operation. (TOMOYO_TYPE_MKCHAR or TOMOYO_TYPE_MKBLOCK)
 * @path:      Pointer to "struct path".
 * @mode:      Create mode.
 * @dev:       Device number.
 *
 * Returns 0 on success, negative value otherwise.
 */
int tomoyo_mkdev_perm(const u8 operation, const struct path *path,
                      const unsigned int mode, unsigned int dev)
{
        struct tomoyo_request_info r;
        struct tomoyo_obj_info obj = {
                .path1 = { .mnt = path->mnt, .dentry = path->dentry },
        };
        int error = -ENOMEM;
        struct tomoyo_path_info buf;
        int idx;

        if (tomoyo_init_request_info(&r, NULL, tomoyo_pnnn2mac[operation])
            == TOMOYO_CONFIG_DISABLED)
                return 0;
        idx = tomoyo_read_lock();
        error = -ENOMEM;
        if (tomoyo_get_realpath(&buf, path)) {
                r.obj = &obj;
                dev = new_decode_dev(dev);
                r.param_type = TOMOYO_TYPE_MKDEV_ACL;
                r.param.mkdev.filename = &buf;
                r.param.mkdev.operation = operation;
                r.param.mkdev.mode = mode;
                r.param.mkdev.major = MAJOR(dev);
                r.param.mkdev.minor = MINOR(dev);
                tomoyo_check_acl(&r, tomoyo_check_mkdev_acl);
                error = tomoyo_audit_mkdev_log(&r);
                kfree(buf.name);
        }
        tomoyo_read_unlock(idx);
        if (r.mode != TOMOYO_CONFIG_ENFORCING)
                error = 0;
        return error;
}

/**
 * tomoyo_path2_perm - Check permission for "rename", "link" and "pivot_root".
 *
 * @operation: Type of operation.
 * @path1:      Pointer to "struct path".
 * @path2:      Pointer to "struct path".
 *
 * Returns 0 on success, negative value otherwise.
 */
int tomoyo_path2_perm(const u8 operation, const struct path *path1,
                      const struct path *path2)
{
        int error = -ENOMEM;
        struct tomoyo_path_info buf1;
        struct tomoyo_path_info buf2;
        struct tomoyo_request_info r;
        struct tomoyo_obj_info obj = {
                .path1 = { .mnt = path1->mnt, .dentry = path1->dentry },
                .path2 = { .mnt = path2->mnt, .dentry = path2->dentry }
        };
        int idx;

        if (tomoyo_init_request_info(&r, NULL, tomoyo_pp2mac[operation])
            == TOMOYO_CONFIG_DISABLED)
                return 0;
        buf1.name = NULL;
        buf2.name = NULL;
        idx = tomoyo_read_lock();
        if (!tomoyo_get_realpath(&buf1, path1) ||
            !tomoyo_get_realpath(&buf2, path2))
                goto out;
        switch (operation) {
        case TOMOYO_TYPE_RENAME:
        case TOMOYO_TYPE_LINK:
                if (!d_is_dir(path1->dentry))
                        break;
                fallthrough;
        case TOMOYO_TYPE_PIVOT_ROOT:
                tomoyo_add_slash(&buf1);
                tomoyo_add_slash(&buf2);
                break;
        }
        r.obj = &obj;
        r.param_type = TOMOYO_TYPE_PATH2_ACL;
        r.param.path2.operation = operation;
        r.param.path2.filename1 = &buf1;
        r.param.path2.filename2 = &buf2;
        do {
                tomoyo_check_acl(&r, tomoyo_check_path2_acl);
                error = tomoyo_audit_path2_log(&r);
        } while (error == TOMOYO_RETRY_REQUEST);
 out:
        kfree(buf1.name);
        kfree(buf2.name);
        tomoyo_read_unlock(idx);
        if (r.mode != TOMOYO_CONFIG_ENFORCING)
                error = 0;
        return error;
}

/**
 * tomoyo_same_mount_acl - Check for duplicated "struct tomoyo_mount_acl" entry.
 *
 * @a: Pointer to "struct tomoyo_acl_info".
 * @b: Pointer to "struct tomoyo_acl_info".
 *
 * Returns true if @a == @b, false otherwise.
 */
static bool tomoyo_same_mount_acl(const struct tomoyo_acl_info *a,
                                  const struct tomoyo_acl_info *b)
{
        const struct tomoyo_mount_acl *p1 = container_of(a, typeof(*p1), head);
        const struct tomoyo_mount_acl *p2 = container_of(b, typeof(*p2), head);

        return tomoyo_same_name_union(&p1->dev_name, &p2->dev_name) &&
                tomoyo_same_name_union(&p1->dir_name, &p2->dir_name) &&
                tomoyo_same_name_union(&p1->fs_type, &p2->fs_type) &&
                tomoyo_same_number_union(&p1->flags, &p2->flags);
}

/**
 * tomoyo_update_mount_acl - Write "struct tomoyo_mount_acl" list.
 *
 * @param: Pointer to "struct tomoyo_acl_param".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
static int tomoyo_update_mount_acl(struct tomoyo_acl_param *param)
{
        struct tomoyo_mount_acl e = { .head.type = TOMOYO_TYPE_MOUNT_ACL };
        int error;

        if (!tomoyo_parse_name_union(param, &e.dev_name) ||
            !tomoyo_parse_name_union(param, &e.dir_name) ||
            !tomoyo_parse_name_union(param, &e.fs_type) ||
            !tomoyo_parse_number_union(param, &e.flags))
                error = -EINVAL;
        else
                error = tomoyo_update_domain(&e.head, sizeof(e), param,
                                             tomoyo_same_mount_acl, NULL);
        tomoyo_put_name_union(&e.dev_name);
        tomoyo_put_name_union(&e.dir_name);
        tomoyo_put_name_union(&e.fs_type);
        tomoyo_put_number_union(&e.flags);
        return error;
}

/**
 * tomoyo_write_file - Update file related list.
 *
 * @param: Pointer to "struct tomoyo_acl_param".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds tomoyo_read_lock().
 */
int tomoyo_write_file(struct tomoyo_acl_param *param)
{
        u16 perm = 0;
        u8 type;
        const char *operation = tomoyo_read_token(param);

        for (type = 0; type < TOMOYO_MAX_PATH_OPERATION; type++)
                if (tomoyo_permstr(operation, tomoyo_path_keyword[type]))
                        perm |= 1 << type;
        if (perm)
                return tomoyo_update_path_acl(perm, param);
        for (type = 0; type < TOMOYO_MAX_PATH2_OPERATION; type++)
                if (tomoyo_permstr(operation,
                                   tomoyo_mac_keywords[tomoyo_pp2mac[type]]))
                        perm |= 1 << type;
        if (perm)
                return tomoyo_update_path2_acl(perm, param);
        for (type = 0; type < TOMOYO_MAX_PATH_NUMBER_OPERATION; type++)
                if (tomoyo_permstr(operation,
                                   tomoyo_mac_keywords[tomoyo_pn2mac[type]]))
                        perm |= 1 << type;
        if (perm)
                return tomoyo_update_path_number_acl(perm, param);
        for (type = 0; type < TOMOYO_MAX_MKDEV_OPERATION; type++)
                if (tomoyo_permstr(operation,
                                   tomoyo_mac_keywords[tomoyo_pnnn2mac[type]]))
                        perm |= 1 << type;
        if (perm)
                return tomoyo_update_mkdev_acl(perm, param);
        if (tomoyo_permstr(operation,
                           tomoyo_mac_keywords[TOMOYO_MAC_FILE_MOUNT]))
                return tomoyo_update_mount_acl(param);
        return -EINVAL;
}