// SPDX-License-Identifier: GPL-2.0
/*
* security/tomoyo/mount.c
*
* Copyright (C) 2005-2011 NTT DATA CORPORATION
*/
#include <linux/slab.h>
#include <uapi/linux/mount.h>
#include "common.h"
/* String table for special mount operations. */
static const char * const tomoyo_mounts[TOMOYO_MAX_SPECIAL_MOUNT] = {
[TOMOYO_MOUNT_BIND] = "--bind",
[TOMOYO_MOUNT_MOVE] = "--move",
[TOMOYO_MOUNT_REMOUNT] = "--remount",
[TOMOYO_MOUNT_MAKE_UNBINDABLE] = "--make-unbindable",
[TOMOYO_MOUNT_MAKE_PRIVATE] = "--make-private",
[TOMOYO_MOUNT_MAKE_SLAVE] = "--make-slave",
[TOMOYO_MOUNT_MAKE_SHARED] = "--make-shared",
};
/**
* tomoyo_audit_mount_log - Audit mount log.
*
* @r: Pointer to "struct tomoyo_request_info".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_audit_mount_log(struct tomoyo_request_info *r)
{
return tomoyo_supervisor(r, "file mount %s %s %s 0x%lX\n",
r->param.mount.dev->name,
r->param.mount.dir->name,
r->param.mount.type->name,
r->param.mount.flags);
}
/**
* tomoyo_check_mount_acl - Check permission for path path 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_mount_acl(struct tomoyo_request_info *r,
const struct tomoyo_acl_info *ptr)
{
const struct tomoyo_mount_acl *acl =
container_of(ptr, typeof(*acl), head);
return tomoyo_compare_number_union(r->param.mount.flags,
&acl->flags) &&
tomoyo_compare_name_union(r->param.mount.type,
&acl->fs_type) &&
tomoyo_compare_name_union(r->param.mount.dir,
&acl->dir_name) &&
(!r->param.mount.need_dev ||
tomoyo_compare_name_union(r->param.mount.dev,
&acl->dev_name));
}
/**
* tomoyo_mount_acl - Check permission for mount() operation.
*
* @r: Pointer to "struct tomoyo_request_info".
* @dev_name: Name of device file. Maybe NULL.
* @dir: Pointer to "struct path".
* @type: Name of filesystem type.
* @flags: Mount options.
*
* Returns 0 on success, negative value otherwise.
*
* Caller holds tomoyo_read_lock().
*/
static int tomoyo_mount_acl(struct tomoyo_request_info *r,
const char *dev_name,
const struct path *dir, const char *type,
unsigned long flags)
{
struct tomoyo_obj_info obj = { };
struct path path;
struct file_system_type *fstype = NULL;
const char *requested_type = NULL;
const char *requested_dir_name = NULL;
const char *requested_dev_name = NULL;
struct tomoyo_path_info rtype;
struct tomoyo_path_info rdev;
struct tomoyo_path_info rdir;
int need_dev = 0;
int error = -ENOMEM;
r->obj = &obj;
/* Get fstype. */
requested_type = tomoyo_encode(type);
if (!requested_type)
goto out;
rtype.name = requested_type;
tomoyo_fill_path_info(&rtype);
/* Get mount point. */
obj.path2 = *dir;
requested_dir_name = tomoyo_realpath_from_path(dir);
if (!requested_dir_name) {
error = -ENOMEM;
goto out;
}
rdir.name = requested_dir_name;
tomoyo_fill_path_info(&rdir);
/* Compare fs name. */
if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]) {
/* dev_name is ignored. */
} else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] ||
type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] ||
type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] ||
type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]) {
/* dev_name is ignored. */
} else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND] ||
type == tomoyo_mounts[TOMOYO_MOUNT_MOVE]) {
need_dev = -1; /* dev_name is a directory */
} else {
fstype = get_fs_type(type);
if (!fstype) {
error = -ENODEV;
goto out;
}
if (fstype->fs_flags & FS_REQUIRES_DEV)
/* dev_name is a block device file. */
need_dev = 1;
}
if (need_dev) {
/* Get mount point or device file. */
if (!dev_name || kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
error = -ENOENT;
goto out;
}
obj.path1 = path;
requested_dev_name = tomoyo_realpath_from_path(&path);
if (!requested_dev_name) {
error = -ENOENT;
goto out;
}
} else {
/* Map dev_name to "<NULL>" if no dev_name given. */
if (!dev_name)
dev_name = "<NULL>";
requested_dev_name = tomoyo_encode(dev_name);
if (!requested_dev_name) {
error = -ENOMEM;
goto out;
}
}
rdev.name = requested_dev_name;
tomoyo_fill_path_info(&rdev);
r->param_type = TOMOYO_TYPE_MOUNT_ACL;
r->param.mount.need_dev = need_dev;
r->param.mount.dev = &rdev;
r->param.mount.dir = &rdir;
r->param.mount.type = &rtype;
r->param.mount.flags = flags;
do {
tomoyo_check_acl(r, tomoyo_check_mount_acl);
error = tomoyo_audit_mount_log(r);
} while (error == TOMOYO_RETRY_REQUEST);
out:
kfree(requested_dev_name);
kfree(requested_dir_name);
if (fstype)
put_filesystem(fstype);
kfree(requested_type);
/* Drop refcount obtained by kern_path(). */
if (obj.path1.dentry)
path_put(&obj.path1);
return error;
}
/**
* tomoyo_mount_permission - Check permission for mount() operation.
*
* @dev_name: Name of device file. Maybe NULL.
* @path: Pointer to "struct path".
* @type: Name of filesystem type. Maybe NULL.
* @flags: Mount options.
* @data_page: Optional data. Maybe NULL.
*
* Returns 0 on success, negative value otherwise.
*/
int tomoyo_mount_permission(const char *dev_name, const struct path *path,
const char *type, unsigned long flags,
void *data_page)
{
struct tomoyo_request_info r;
int error;
int idx;
if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
== TOMOYO_CONFIG_DISABLED)
return 0;
if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
flags &= ~MS_MGC_MSK;
if (flags & MS_REMOUNT) {
type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT];
flags &= ~MS_REMOUNT;
} else if (flags & MS_BIND) {
type = tomoyo_mounts[TOMOYO_MOUNT_BIND];
flags &= ~MS_BIND;
} else if (flags & MS_SHARED) {
if (flags & (MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
return -EINVAL;
type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
flags &= ~MS_SHARED;
} else if (flags & MS_PRIVATE) {
if (flags & (MS_SHARED | MS_SLAVE | MS_UNBINDABLE))
return -EINVAL;
type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];
flags &= ~MS_PRIVATE;
} else if (flags & MS_SLAVE) {
if (flags & (MS_SHARED | MS_PRIVATE | MS_UNBINDABLE))
return -EINVAL;
type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];
flags &= ~MS_SLAVE;
} else if (flags & MS_UNBINDABLE) {
if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE))
return -EINVAL;
type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
flags &= ~MS_UNBINDABLE;
} else if (flags & MS_MOVE) {
type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
flags &= ~MS_MOVE;
}
if (!type)
type = "<NULL>";
idx = tomoyo_read_lock();
error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
tomoyo_read_unlock(idx);
return error;
}
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