[mirror_ubuntu-jammy-kernel.git] / fs / attr.c

/*
 *  linux/fs/attr.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  changes by Thomas Schoebel-Theuer
 */

#include <linux/export.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/capability.h>
#include <linux/fsnotify.h>
#include <linux/fcntl.h>
#include <linux/security.h>
#include <linux/evm.h>
#include <linux/ima.h>

/**
 * setattr_prepare - check if attribute changes to a dentry are allowed
 * @dentry:	dentry to check
 * @attr:	attributes to change
 *
 * Check if we are allowed to change the attributes contained in @attr
 * in the given dentry.  This includes the normal unix access permission
 * checks, as well as checks for rlimits and others. The function also clears
 * SGID bit from mode if user is not allowed to set it. Also file capabilities
 * and IMA extended attributes are cleared if ATTR_KILL_PRIV is set.
 *
 * Should be called as the first thing in ->setattr implementations,
 * possibly after taking additional locks.
 */
int setattr_prepare(struct dentry *dentry, struct iattr *attr)
{
	struct inode *inode = d_inode(dentry);
	unsigned int ia_valid = attr->ia_valid;

	/*
	 * First check size constraints.  These can't be overriden using
	 * ATTR_FORCE.
	 */
	if (ia_valid & ATTR_SIZE) {
		int error = inode_newsize_ok(inode, attr->ia_size);
		if (error)
			return error;
	}

	/* If force is set do it anyway. */
	if (ia_valid & ATTR_FORCE)
		goto kill_priv;

	/* Make sure a caller can chown. */
	if ((ia_valid & ATTR_UID) &&
	    (!uid_eq(current_fsuid(), inode->i_uid) ||
	     !uid_eq(attr->ia_uid, inode->i_uid)) &&
	    !capable_wrt_inode_uidgid(inode, CAP_CHOWN))
		return -EPERM;

	/* Make sure caller can chgrp. */
	if ((ia_valid & ATTR_GID) &&
	    (!uid_eq(current_fsuid(), inode->i_uid) ||
	    (!in_group_p(attr->ia_gid) && !gid_eq(attr->ia_gid, inode->i_gid))) &&
	    !capable_wrt_inode_uidgid(inode, CAP_CHOWN))
		return -EPERM;

	/* Make sure a caller can chmod. */
	if (ia_valid & ATTR_MODE) {
		if (!inode_owner_or_capable(inode))
			return -EPERM;
		/* Also check the setgid bit! */
		if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
				inode->i_gid) &&
		    !capable_wrt_inode_uidgid(inode, CAP_FSETID))
			attr->ia_mode &= ~S_ISGID;
	}

	/* Check for setting the inode time. */
	if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
		if (!inode_owner_or_capable(inode))
			return -EPERM;
	}

kill_priv:
	/* User has permission for the change */
	if (ia_valid & ATTR_KILL_PRIV) {
		int error;

		error = security_inode_killpriv(dentry);
		if (error)
			return error;
	}

	return 0;
}
EXPORT_SYMBOL(setattr_prepare);

/**
 * inode_newsize_ok - may this inode be truncated to a given size
 * @inode:	the inode to be truncated
 * @offset:	the new size to assign to the inode
 * @Returns:	0 on success, -ve errno on failure
 *
 * inode_newsize_ok must be called with i_mutex held.
 *
 * inode_newsize_ok will check filesystem limits and ulimits to check that the
 * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
 * when necessary. Caller must not proceed with inode size change if failure is
 * returned. @inode must be a file (not directory), with appropriate
 * permissions to allow truncate (inode_newsize_ok does NOT check these
 * conditions).
 */
int inode_newsize_ok(const struct inode *inode, loff_t offset)
{
	if (inode->i_size < offset) {
		unsigned long limit;

		limit = rlimit(RLIMIT_FSIZE);
		if (limit != RLIM_INFINITY && offset > limit)
			goto out_sig;
		if (offset > inode->i_sb->s_maxbytes)
			goto out_big;
	} else {
		/*
		 * truncation of in-use swapfiles is disallowed - it would
		 * cause subsequent swapout to scribble on the now-freed
		 * blocks.
		 */
		if (IS_SWAPFILE(inode))
			return -ETXTBSY;
	}

	return 0;
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
}
EXPORT_SYMBOL(inode_newsize_ok);

/**
 * setattr_copy - copy simple metadata updates into the generic inode
 * @inode:	the inode to be updated
 * @attr:	the new attributes
 *
 * setattr_copy must be called with i_mutex held.
 *
 * setattr_copy updates the inode's metadata with that specified
 * in attr. Noticeably missing is inode size update, which is more complex
 * as it requires pagecache updates.
 *
 * The inode is not marked as dirty after this operation. The rationale is
 * that for "simple" filesystems, the struct inode is the inode storage.
 * The caller is free to mark the inode dirty afterwards if needed.
 */
void setattr_copy(struct inode *inode, const struct iattr *attr)
{
	unsigned int ia_valid = attr->ia_valid;

	if (ia_valid & ATTR_UID)
		inode->i_uid = attr->ia_uid;
	if (ia_valid & ATTR_GID)
		inode->i_gid = attr->ia_gid;
	if (ia_valid & ATTR_ATIME)
		inode->i_atime = timespec_trunc(attr->ia_atime,
						inode->i_sb->s_time_gran);
	if (ia_valid & ATTR_MTIME)
		inode->i_mtime = timespec_trunc(attr->ia_mtime,
						inode->i_sb->s_time_gran);
	if (ia_valid & ATTR_CTIME)
		inode->i_ctime = timespec_trunc(attr->ia_ctime,
						inode->i_sb->s_time_gran);
	if (ia_valid & ATTR_MODE) {
		umode_t mode = attr->ia_mode;

		if (!in_group_p(inode->i_gid) &&
		    !capable_wrt_inode_uidgid(inode, CAP_FSETID))
			mode &= ~S_ISGID;
		inode->i_mode = mode;
	}
}
EXPORT_SYMBOL(setattr_copy);

/**
 * notify_change - modify attributes of a filesytem object
 * @dentry:	object affected
 * @iattr:	new attributes
 * @delegated_inode: returns inode, if the inode is delegated
 *
 * The caller must hold the i_mutex on the affected object.
 *
 * If notify_change discovers a delegation in need of breaking,
 * it will return -EWOULDBLOCK and return a reference to the inode in
 * delegated_inode.  The caller should then break the delegation and
 * retry.  Because breaking a delegation may take a long time, the
 * caller should drop the i_mutex before doing so.
 *
 * Alternatively, a caller may pass NULL for delegated_inode.  This may
 * be appropriate for callers that expect the underlying filesystem not
 * to be NFS exported.  Also, passing NULL is fine for callers holding
 * the file open for write, as there can be no conflicting delegation in
 * that case.
 */
int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **delegated_inode)
{
	struct inode *inode = dentry->d_inode;
	umode_t mode = inode->i_mode;
	int error;
	struct timespec now;
	unsigned int ia_valid = attr->ia_valid;

	WARN_ON_ONCE(!inode_is_locked(inode));

	if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
		if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
			return -EPERM;
	}

	/*
	 * If utimes(2) and friends are called with times == NULL (or both
	 * times are UTIME_NOW), then we need to check for write permission
	 */
	if (ia_valid & ATTR_TOUCH) {
		if (IS_IMMUTABLE(inode))
			return -EPERM;

		if (!inode_owner_or_capable(inode)) {
			error = inode_permission(inode, MAY_WRITE);
			if (error)
				return error;
		}
	}

	if ((ia_valid & ATTR_MODE)) {
		umode_t amode = attr->ia_mode;
		/* Flag setting protected by i_mutex */
		if (is_sxid(amode))
			inode->i_flags &= ~S_NOSEC;
	}

	now = current_time(inode);

	attr->ia_ctime = now;
	if (!(ia_valid & ATTR_ATIME_SET))
		attr->ia_atime = now;
	if (!(ia_valid & ATTR_MTIME_SET))
		attr->ia_mtime = now;
	if (ia_valid & ATTR_KILL_PRIV) {
		error = security_inode_need_killpriv(dentry);
		if (error < 0)
			return error;
		if (error == 0)
			ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV;
	}

	/*
	 * We now pass ATTR_KILL_S*ID to the lower level setattr function so
	 * that the function has the ability to reinterpret a mode change
	 * that's due to these bits. This adds an implicit restriction that
	 * no function will ever call notify_change with both ATTR_MODE and
	 * ATTR_KILL_S*ID set.
	 */
	if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
	    (ia_valid & ATTR_MODE))
		BUG();

	if (ia_valid & ATTR_KILL_SUID) {
		if (mode & S_ISUID) {
			ia_valid = attr->ia_valid |= ATTR_MODE;
			attr->ia_mode = (inode->i_mode & ~S_ISUID);
		}
	}
	if (ia_valid & ATTR_KILL_SGID) {
		if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
			if (!(ia_valid & ATTR_MODE)) {
				ia_valid = attr->ia_valid |= ATTR_MODE;
				attr->ia_mode = inode->i_mode;
			}
			attr->ia_mode &= ~S_ISGID;
		}
	}
	if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
		return 0;

	/*
	 * Verify that uid/gid changes are valid in the target
	 * namespace of the superblock.
	 */
	if (ia_valid & ATTR_UID &&
	    !kuid_has_mapping(inode->i_sb->s_user_ns, attr->ia_uid))
		return -EOVERFLOW;
	if (ia_valid & ATTR_GID &&
	    !kgid_has_mapping(inode->i_sb->s_user_ns, attr->ia_gid))
		return -EOVERFLOW;

	/* Don't allow modifications of files with invalid uids or
	 * gids unless those uids & gids are being made valid.
	 */
	if (!(ia_valid & ATTR_UID) && !uid_valid(inode->i_uid))
		return -EOVERFLOW;
	if (!(ia_valid & ATTR_GID) && !gid_valid(inode->i_gid))
		return -EOVERFLOW;

	error = security_inode_setattr(dentry, attr);
	if (error)
		return error;
	error = try_break_deleg(inode, delegated_inode);
	if (error)
		return error;

	if (inode->i_op->setattr)
		error = inode->i_op->setattr(dentry, attr);
	else
		error = simple_setattr(dentry, attr);

	if (!error) {
		fsnotify_change(dentry, ia_valid);
		ima_inode_post_setattr(dentry);
		evm_inode_post_setattr(dentry, ia_valid);
	}

	return error;
}
EXPORT_SYMBOL(notify_change);
Commit	Line	Data
	1	/*
	2	* linux/fs/attr.c
	3	*
	4	* Copyright (C) 1991, 1992 Linus Torvalds
	5	* changes by Thomas Schoebel-Theuer
	6	*/
	7
	8	#include <linux/export.h>
	9	#include <linux/time.h>
	10	#include <linux/mm.h>
	11	#include <linux/string.h>
	12	#include <linux/capability.h>
	13	#include <linux/fsnotify.h>
	14	#include <linux/fcntl.h>
	15	#include <linux/security.h>
	16	#include <linux/evm.h>
	17	#include <linux/ima.h>
	18
	19	/**
	20	* setattr_prepare - check if attribute changes to a dentry are allowed
	21	* @dentry: dentry to check
	22	* @attr: attributes to change
	23	*
	24	* Check if we are allowed to change the attributes contained in @attr
	25	* in the given dentry. This includes the normal unix access permission
	26	* checks, as well as checks for rlimits and others. The function also clears
	27	* SGID bit from mode if user is not allowed to set it. Also file capabilities
	28	* and IMA extended attributes are cleared if ATTR_KILL_PRIV is set.
	29	*
	30	* Should be called as the first thing in ->setattr implementations,
	31	* possibly after taking additional locks.
	32	*/
	33	int setattr_prepare(struct dentry dentry, struct iattr attr)
	34	{
	35	struct inode *inode = d_inode(dentry);
	36	unsigned int ia_valid = attr->ia_valid;
	37
	38	/*
	39	* First check size constraints. These can't be overriden using
	40	* ATTR_FORCE.
	41	*/
	42	if (ia_valid & ATTR_SIZE) {
	43	int error = inode_newsize_ok(inode, attr->ia_size);
	44	if (error)
	45	return error;
	46	}
	47
	48	/* If force is set do it anyway. */
	49	if (ia_valid & ATTR_FORCE)
	50	goto kill_priv;
	51
	52	/* Make sure a caller can chown. */
	53	if ((ia_valid & ATTR_UID) &&
	54	(!uid_eq(current_fsuid(), inode->i_uid) \|\|
	55	!uid_eq(attr->ia_uid, inode->i_uid)) &&
	56	!capable_wrt_inode_uidgid(inode, CAP_CHOWN))
	57	return -EPERM;
	58
	59	/* Make sure caller can chgrp. */
	60	if ((ia_valid & ATTR_GID) &&
	61	(!uid_eq(current_fsuid(), inode->i_uid) \|\|
	62	(!in_group_p(attr->ia_gid) && !gid_eq(attr->ia_gid, inode->i_gid))) &&
	63	!capable_wrt_inode_uidgid(inode, CAP_CHOWN))
	64	return -EPERM;
	65
	66	/* Make sure a caller can chmod. */
	67	if (ia_valid & ATTR_MODE) {
	68	if (!inode_owner_or_capable(inode))
	69	return -EPERM;
	70	/* Also check the setgid bit! */
	71	if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
	72	inode->i_gid) &&
	73	!capable_wrt_inode_uidgid(inode, CAP_FSETID))
	74	attr->ia_mode &= ~S_ISGID;
	75	}
	76
	77	/* Check for setting the inode time. */
	78	if (ia_valid & (ATTR_MTIME_SET \| ATTR_ATIME_SET \| ATTR_TIMES_SET)) {
	79	if (!inode_owner_or_capable(inode))
	80	return -EPERM;
	81	}
	82
	83	kill_priv:
	84	/* User has permission for the change */
	85	if (ia_valid & ATTR_KILL_PRIV) {
	86	int error;
	87
	88	error = security_inode_killpriv(dentry);
	89	if (error)
	90	return error;
	91	}
	92
	93	return 0;
	94	}
	95	EXPORT_SYMBOL(setattr_prepare);
	96
	97	/**
	98	* inode_newsize_ok - may this inode be truncated to a given size
	99	* @inode: the inode to be truncated
	100	* @offset: the new size to assign to the inode
	101	* @Returns: 0 on success, -ve errno on failure
	102	*
	103	* inode_newsize_ok must be called with i_mutex held.
	104	*
	105	* inode_newsize_ok will check filesystem limits and ulimits to check that the
	106	* new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
	107	* when necessary. Caller must not proceed with inode size change if failure is
	108	* returned. @inode must be a file (not directory), with appropriate
	109	* permissions to allow truncate (inode_newsize_ok does NOT check these
	110	* conditions).
	111	*/
	112	int inode_newsize_ok(const struct inode *inode, loff_t offset)
	113	{
	114	if (inode->i_size < offset) {
	115	unsigned long limit;
	116
	117	limit = rlimit(RLIMIT_FSIZE);
	118	if (limit != RLIM_INFINITY && offset > limit)
	119	goto out_sig;
	120	if (offset > inode->i_sb->s_maxbytes)
	121	goto out_big;
	122	} else {
	123	/*
	124	* truncation of in-use swapfiles is disallowed - it would
	125	* cause subsequent swapout to scribble on the now-freed
	126	* blocks.
	127	*/
	128	if (IS_SWAPFILE(inode))
	129	return -ETXTBSY;
	130	}
	131
	132	return 0;
	133	out_sig:
	134	send_sig(SIGXFSZ, current, 0);
	135	out_big:
	136	return -EFBIG;
	137	}
	138	EXPORT_SYMBOL(inode_newsize_ok);
	139
	140	/**
	141	* setattr_copy - copy simple metadata updates into the generic inode
	142	* @inode: the inode to be updated
	143	* @attr: the new attributes
	144	*
	145	* setattr_copy must be called with i_mutex held.
	146	*
	147	* setattr_copy updates the inode's metadata with that specified
	148	* in attr. Noticeably missing is inode size update, which is more complex
	149	* as it requires pagecache updates.
	150	*
	151	* The inode is not marked as dirty after this operation. The rationale is
	152	* that for "simple" filesystems, the struct inode is the inode storage.
	153	* The caller is free to mark the inode dirty afterwards if needed.
	154	*/
	155	void setattr_copy(struct inode inode, const struct iattr attr)
	156	{
	157	unsigned int ia_valid = attr->ia_valid;
	158
	159	if (ia_valid & ATTR_UID)
	160	inode->i_uid = attr->ia_uid;
	161	if (ia_valid & ATTR_GID)
	162	inode->i_gid = attr->ia_gid;
	163	if (ia_valid & ATTR_ATIME)
	164	inode->i_atime = timespec_trunc(attr->ia_atime,
	165	inode->i_sb->s_time_gran);
	166	if (ia_valid & ATTR_MTIME)
	167	inode->i_mtime = timespec_trunc(attr->ia_mtime,
	168	inode->i_sb->s_time_gran);
	169	if (ia_valid & ATTR_CTIME)
	170	inode->i_ctime = timespec_trunc(attr->ia_ctime,
	171	inode->i_sb->s_time_gran);
	172	if (ia_valid & ATTR_MODE) {
	173	umode_t mode = attr->ia_mode;
	174
	175	if (!in_group_p(inode->i_gid) &&
	176	!capable_wrt_inode_uidgid(inode, CAP_FSETID))
	177	mode &= ~S_ISGID;
	178	inode->i_mode = mode;
	179	}
	180	}
	181	EXPORT_SYMBOL(setattr_copy);
	182
	183	/**
	184	* notify_change - modify attributes of a filesytem object
	185	* @dentry: object affected
	186	* @iattr: new attributes
	187	* @delegated_inode: returns inode, if the inode is delegated
	188	*
	189	* The caller must hold the i_mutex on the affected object.
	190	*
	191	* If notify_change discovers a delegation in need of breaking,
	192	* it will return -EWOULDBLOCK and return a reference to the inode in
	193	* delegated_inode. The caller should then break the delegation and
	194	* retry. Because breaking a delegation may take a long time, the
	195	* caller should drop the i_mutex before doing so.
	196	*
	197	* Alternatively, a caller may pass NULL for delegated_inode. This may
	198	* be appropriate for callers that expect the underlying filesystem not
	199	* to be NFS exported. Also, passing NULL is fine for callers holding
	200	* the file open for write, as there can be no conflicting delegation in
	201	* that case.
	202	*/
	203	int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **delegated_inode)
	204	{
	205	struct inode *inode = dentry->d_inode;
	206	umode_t mode = inode->i_mode;
	207	int error;
	208	struct timespec now;
	209	unsigned int ia_valid = attr->ia_valid;
	210
	211	WARN_ON_ONCE(!inode_is_locked(inode));
	212
	213	if (ia_valid & (ATTR_MODE \| ATTR_UID \| ATTR_GID \| ATTR_TIMES_SET)) {
	214	if (IS_IMMUTABLE(inode) \|\| IS_APPEND(inode))
	215	return -EPERM;
	216	}
	217
	218	/*
	219	* If utimes(2) and friends are called with times == NULL (or both
	220	* times are UTIME_NOW), then we need to check for write permission
	221	*/
	222	if (ia_valid & ATTR_TOUCH) {
	223	if (IS_IMMUTABLE(inode))
	224	return -EPERM;
	225
	226	if (!inode_owner_or_capable(inode)) {
	227	error = inode_permission(inode, MAY_WRITE);
	228	if (error)
	229	return error;
	230	}
	231	}
	232
	233	if ((ia_valid & ATTR_MODE)) {
	234	umode_t amode = attr->ia_mode;
	235	/* Flag setting protected by i_mutex */
	236	if (is_sxid(amode))
	237	inode->i_flags &= ~S_NOSEC;
	238	}
	239
	240	now = current_time(inode);
	241
	242	attr->ia_ctime = now;
	243	if (!(ia_valid & ATTR_ATIME_SET))
	244	attr->ia_atime = now;
	245	if (!(ia_valid & ATTR_MTIME_SET))
	246	attr->ia_mtime = now;
	247	if (ia_valid & ATTR_KILL_PRIV) {
	248	error = security_inode_need_killpriv(dentry);
	249	if (error < 0)
	250	return error;
	251	if (error == 0)
	252	ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV;
	253	}
	254
	255	/*
	256	* We now pass ATTR_KILL_S*ID to the lower level setattr function so
	257	* that the function has the ability to reinterpret a mode change
	258	* that's due to these bits. This adds an implicit restriction that
	259	* no function will ever call notify_change with both ATTR_MODE and
	260	* ATTR_KILL_S*ID set.
	261	*/
	262	if ((ia_valid & (ATTR_KILL_SUID\|ATTR_KILL_SGID)) &&
	263	(ia_valid & ATTR_MODE))
	264	BUG();
	265
	266	if (ia_valid & ATTR_KILL_SUID) {
	267	if (mode & S_ISUID) {
	268	ia_valid = attr->ia_valid \|= ATTR_MODE;
	269	attr->ia_mode = (inode->i_mode & ~S_ISUID);
	270	}
	271	}
	272	if (ia_valid & ATTR_KILL_SGID) {
	273	if ((mode & (S_ISGID \| S_IXGRP)) == (S_ISGID \| S_IXGRP)) {
	274	if (!(ia_valid & ATTR_MODE)) {
	275	ia_valid = attr->ia_valid \|= ATTR_MODE;
	276	attr->ia_mode = inode->i_mode;
	277	}
	278	attr->ia_mode &= ~S_ISGID;
	279	}
	280	}
	281	if (!(attr->ia_valid & ~(ATTR_KILL_SUID \| ATTR_KILL_SGID)))
	282	return 0;
	283
	284	/*
	285	* Verify that uid/gid changes are valid in the target
	286	* namespace of the superblock.
	287	*/
	288	if (ia_valid & ATTR_UID &&
	289	!kuid_has_mapping(inode->i_sb->s_user_ns, attr->ia_uid))
	290	return -EOVERFLOW;
	291	if (ia_valid & ATTR_GID &&
	292	!kgid_has_mapping(inode->i_sb->s_user_ns, attr->ia_gid))
	293	return -EOVERFLOW;
	294
	295	/* Don't allow modifications of files with invalid uids or
	296	* gids unless those uids & gids are being made valid.
	297	*/
	298	if (!(ia_valid & ATTR_UID) && !uid_valid(inode->i_uid))
	299	return -EOVERFLOW;
	300	if (!(ia_valid & ATTR_GID) && !gid_valid(inode->i_gid))
	301	return -EOVERFLOW;
	302
	303	error = security_inode_setattr(dentry, attr);
	304	if (error)
	305	return error;
	306	error = try_break_deleg(inode, delegated_inode);
	307	if (error)
	308	return error;
	309
	310	if (inode->i_op->setattr)
	311	error = inode->i_op->setattr(dentry, attr);
	312	else
	313	error = simple_setattr(dentry, attr);
	314
	315	if (!error) {
	316	fsnotify_change(dentry, ia_valid);
	317	ima_inode_post_setattr(dentry);
	318	evm_inode_post_setattr(dentry, ia_valid);
	319	}
	320
	321	return error;
	322	}
	323	EXPORT_SYMBOL(notify_change);