[people/ms/linux.git] / security / tomoyo / mount.c

// 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;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
2106ccd9 TH	2	/*
	3	* security/tomoyo/mount.c
	4	*
0f2a55d5	5	* Copyright (C) 2005-2011 NTT DATA CORPORATION
2106ccd9 TH	6	*/
	7
	8	#include <linux/slab.h>
e262e32d	9	#include <uapi/linux/mount.h>
2106ccd9 TH	10	#include "common.h"
2106ccd9 TH	11
b5bc60b4 TH	12	/* String table for special mount operations. */
	13	static const char * const tomoyo_mounts[TOMOYO_MAX_SPECIAL_MOUNT] = {
	14	[TOMOYO_MOUNT_BIND] = "--bind",
	15	[TOMOYO_MOUNT_MOVE] = "--move",
	16	[TOMOYO_MOUNT_REMOUNT] = "--remount",
	17	[TOMOYO_MOUNT_MAKE_UNBINDABLE] = "--make-unbindable",
	18	[TOMOYO_MOUNT_MAKE_PRIVATE] = "--make-private",
	19	[TOMOYO_MOUNT_MAKE_SLAVE] = "--make-slave",
	20	[TOMOYO_MOUNT_MAKE_SHARED] = "--make-shared",
	21	};
2106ccd9	22
99a85259 TH	23	/**
	24	* tomoyo_audit_mount_log - Audit mount log.
	25	*
	26	* @r: Pointer to "struct tomoyo_request_info".
	27	*
	28	* Returns 0 on success, negative value otherwise.
	29	*/
	30	static int tomoyo_audit_mount_log(struct tomoyo_request_info *r)
	31	{
eadd99cc	32	return tomoyo_supervisor(r, "file mount %s %s %s 0x%lX\n",
7c75964f	33	r->param.mount.dev->name,
eadd99cc TH	34	r->param.mount.dir->name,
	35	r->param.mount.type->name,
	36	r->param.mount.flags);
99a85259 TH	37	}
99a85259 TH	38
0df7e8b8 TH	39	/**
	40	* tomoyo_check_mount_acl - Check permission for path path path number operation.
	41	*
	42	* @r: Pointer to "struct tomoyo_request_info".
	43	* @ptr: Pointer to "struct tomoyo_acl_info".
	44	*
	45	* Returns true if granted, false otherwise.
	46	*/
484ca79c	47	static bool tomoyo_check_mount_acl(struct tomoyo_request_info *r,
99a85259 TH	48	const struct tomoyo_acl_info *ptr)
	49	{
	50	const struct tomoyo_mount_acl *acl =
	51	container_of(ptr, typeof(*acl), head);
cdcf6723	52
0df7e8b8 TH	53	return tomoyo_compare_number_union(r->param.mount.flags,
	54	&acl->flags) &&
	55	tomoyo_compare_name_union(r->param.mount.type,
	56	&acl->fs_type) &&
	57	tomoyo_compare_name_union(r->param.mount.dir,
	58	&acl->dir_name) &&
99a85259	59	(!r->param.mount.need_dev \|\|
0df7e8b8 TH	60	tomoyo_compare_name_union(r->param.mount.dev,
0df7e8b8 TH	61	&acl->dev_name));
99a85259 TH	62	}
99a85259 TH	63
2106ccd9	64	/**
d795ef9e	65	* tomoyo_mount_acl - Check permission for mount() operation.
2106ccd9 TH	66	*
2106ccd9 TH	67	* @r: Pointer to "struct tomoyo_request_info".
0f2a55d5	68	* @dev_name: Name of device file. Maybe NULL.
2106ccd9 TH	69	* @dir: Pointer to "struct path".
	70	* @type: Name of filesystem type.
	71	* @flags: Mount options.
	72	*
	73	* Returns 0 on success, negative value otherwise.
	74	*
	75	* Caller holds tomoyo_read_lock().
	76	*/
808d4e3c AV	77	static int tomoyo_mount_acl(struct tomoyo_request_info *r,
808d4e3c AV	78	const char *dev_name,
e6641edd	79	const struct path dir, const char type,
b5bc60b4	80	unsigned long flags)
2106ccd9	81	{
97fb35e4	82	struct tomoyo_obj_info obj = { };
2106ccd9	83	struct path path;
2106ccd9 TH	84	struct file_system_type *fstype = NULL;
	85	const char *requested_type = NULL;
	86	const char *requested_dir_name = NULL;
	87	const char *requested_dev_name = NULL;
	88	struct tomoyo_path_info rtype;
	89	struct tomoyo_path_info rdev;
	90	struct tomoyo_path_info rdir;
	91	int need_dev = 0;
	92	int error = -ENOMEM;
cdcf6723	93
97fb35e4	94	r->obj = &obj;
2106ccd9 TH	95
2106ccd9 TH	96	/* Get fstype. */
c8c57e84	97	requested_type = tomoyo_encode(type);
2106ccd9 TH	98	if (!requested_type)
	99	goto out;
	100	rtype.name = requested_type;
	101	tomoyo_fill_path_info(&rtype);
	102
	103	/* Get mount point. */
97fb35e4	104	obj.path2 = *dir;
2106ccd9 TH	105	requested_dir_name = tomoyo_realpath_from_path(dir);
	106	if (!requested_dir_name) {
	107	error = -ENOMEM;
	108	goto out;
	109	}
	110	rdir.name = requested_dir_name;
	111	tomoyo_fill_path_info(&rdir);
	112
	113	/* Compare fs name. */
b5bc60b4	114	if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]) {
2106ccd9	115	/* dev_name is ignored. */
b5bc60b4 TH	116	} else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] \|\|
	117	type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] \|\|
	118	type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] \|\|
	119	type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]) {
2106ccd9	120	/* dev_name is ignored. */
b5bc60b4 TH	121	} else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND] \|\|
b5bc60b4 TH	122	type == tomoyo_mounts[TOMOYO_MOUNT_MOVE]) {
2106ccd9 TH	123	need_dev = -1; /* dev_name is a directory */
	124	} else {
	125	fstype = get_fs_type(type);
	126	if (!fstype) {
	127	error = -ENODEV;
	128	goto out;
	129	}
	130	if (fstype->fs_flags & FS_REQUIRES_DEV)
	131	/* dev_name is a block device file. */
	132	need_dev = 1;
	133	}
	134	if (need_dev) {
	135	/* Get mount point or device file. */
4e78c724	136	if (!dev_name \|\| kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
2106ccd9 TH	137	error = -ENOENT;
	138	goto out;
	139	}
97fb35e4	140	obj.path1 = path;
2106ccd9 TH	141	requested_dev_name = tomoyo_realpath_from_path(&path);
	142	if (!requested_dev_name) {
	143	error = -ENOENT;
	144	goto out;
	145	}
	146	} else {
	147	/* Map dev_name to "<NULL>" if no dev_name given. */
	148	if (!dev_name)
	149	dev_name = "<NULL>";
c8c57e84	150	requested_dev_name = tomoyo_encode(dev_name);
2106ccd9 TH	151	if (!requested_dev_name) {
	152	error = -ENOMEM;
	153	goto out;
	154	}
	155	}
	156	rdev.name = requested_dev_name;
	157	tomoyo_fill_path_info(&rdev);
cf6e9a64 TH	158	r->param_type = TOMOYO_TYPE_MOUNT_ACL;
	159	r->param.mount.need_dev = need_dev;
	160	r->param.mount.dev = &rdev;
	161	r->param.mount.dir = &rdir;
	162	r->param.mount.type = &rtype;
	163	r->param.mount.flags = flags;
99a85259 TH	164	do {
	165	tomoyo_check_acl(r, tomoyo_check_mount_acl);
	166	error = tomoyo_audit_mount_log(r);
	167	} while (error == TOMOYO_RETRY_REQUEST);
2106ccd9 TH	168	out:
	169	kfree(requested_dev_name);
	170	kfree(requested_dir_name);
	171	if (fstype)
	172	put_filesystem(fstype);
	173	kfree(requested_type);
97fb35e4 TH	174	/* Drop refcount obtained by kern_path(). */
	175	if (obj.path1.dentry)
	176	path_put(&obj.path1);
2106ccd9 TH	177	return error;
	178	}
	179
2106ccd9 TH	180	/**
	181	* tomoyo_mount_permission - Check permission for mount() operation.
	182	*
0f2a55d5	183	* @dev_name: Name of device file. Maybe NULL.
2106ccd9	184	* @path: Pointer to "struct path".
0f2a55d5	185	* @type: Name of filesystem type. Maybe NULL.
2106ccd9	186	* @flags: Mount options.
0f2a55d5	187	* @data_page: Optional data. Maybe NULL.
2106ccd9 TH	188	*
	189	* Returns 0 on success, negative value otherwise.
	190	*/
e6641edd	191	int tomoyo_mount_permission(const char dev_name, const struct path path,
b5bc60b4 TH	192	const char *type, unsigned long flags,
b5bc60b4 TH	193	void *data_page)
2106ccd9 TH	194	{
	195	struct tomoyo_request_info r;
	196	int error;
	197	int idx;
	198
57c2590f TH	199	if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
57c2590f TH	200	== TOMOYO_CONFIG_DISABLED)
2106ccd9	201	return 0;
d795ef9e TH	202	if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
	203	flags &= ~MS_MGC_MSK;
	204	if (flags & MS_REMOUNT) {
b5bc60b4	205	type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT];
d795ef9e	206	flags &= ~MS_REMOUNT;
df91e494	207	} else if (flags & MS_BIND) {
b5bc60b4	208	type = tomoyo_mounts[TOMOYO_MOUNT_BIND];
d795ef9e	209	flags &= ~MS_BIND;
df91e494 TH	210	} else if (flags & MS_SHARED) {
	211	if (flags & (MS_PRIVATE \| MS_SLAVE \| MS_UNBINDABLE))
	212	return -EINVAL;
	213	type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
	214	flags &= ~MS_SHARED;
	215	} else if (flags & MS_PRIVATE) {
	216	if (flags & (MS_SHARED \| MS_SLAVE \| MS_UNBINDABLE))
	217	return -EINVAL;
b5bc60b4	218	type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];
d795ef9e	219	flags &= ~MS_PRIVATE;
df91e494 TH	220	} else if (flags & MS_SLAVE) {
	221	if (flags & (MS_SHARED \| MS_PRIVATE \| MS_UNBINDABLE))
	222	return -EINVAL;
b5bc60b4	223	type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];
d795ef9e	224	flags &= ~MS_SLAVE;
df91e494 TH	225	} else if (flags & MS_UNBINDABLE) {
	226	if (flags & (MS_SHARED \| MS_PRIVATE \| MS_SLAVE))
	227	return -EINVAL;
	228	type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
	229	flags &= ~MS_UNBINDABLE;
	230	} else if (flags & MS_MOVE) {
	231	type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
	232	flags &= ~MS_MOVE;
d795ef9e	233	}
2106ccd9 TH	234	if (!type)
	235	type = "<NULL>";
	236	idx = tomoyo_read_lock();
	237	error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
	238	tomoyo_read_unlock(idx);
	239	return error;
	240	}