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

// SPDX-License-Identifier: GPL-2.0
/*
 *  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/sched/signal.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>

static bool chown_ok(const struct inode *inode, kuid_t uid)
{
	if (uid_eq(current_fsuid(), inode->i_uid) &&
	    uid_eq(uid, inode->i_uid))
		return true;
	if (capable_wrt_inode_uidgid(inode, CAP_CHOWN))
		return true;
	if (uid_eq(inode->i_uid, INVALID_UID) &&
	    ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
		return true;
	return false;
}

static bool chgrp_ok(const struct inode *inode, kgid_t gid)
{
	if (uid_eq(current_fsuid(), inode->i_uid) &&
	    (in_group_p(gid) || gid_eq(gid, inode->i_gid)))
		return true;
	if (capable_wrt_inode_uidgid(inode, CAP_CHOWN))
		return true;
	if (gid_eq(inode->i_gid, INVALID_GID) &&
	    ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
		return true;
	return false;
}

/**
 * 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) && !chown_ok(inode, attr->ia_uid))
		return -EPERM;

	/* Make sure caller can chgrp. */
	if ((ia_valid & ATTR_GID) && !chgrp_ok(inode, attr->ia_gid))
		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
 *
 * 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).
 *
 * Return: 0 on success, -ve errno on failure
 */
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 = timespec64_trunc(attr->ia_atime,
						  inode->i_sb->s_time_gran);
	if (ia_valid & ATTR_MTIME)
		inode->i_mtime = timespec64_trunc(attr->ia_mtime,
						  inode->i_sb->s_time_gran);
	if (ia_valid & ATTR_CTIME)
		inode->i_ctime = timespec64_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
 * @attr:	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 timespec64 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
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1da177e4 LT	2	/*
	3	* linux/fs/attr.c
	4	*
	5	* Copyright (C) 1991, 1992 Linus Torvalds
	6	* changes by Thomas Schoebel-Theuer
	7	*/
	8
630d9c47	9	#include <linux/export.h>
1da177e4 LT	10	#include <linux/time.h>
	11	#include <linux/mm.h>
	12	#include <linux/string.h>
3f07c014	13	#include <linux/sched/signal.h>
16f7e0fe	14	#include <linux/capability.h>
0eeca283	15	#include <linux/fsnotify.h>
1da177e4	16	#include <linux/fcntl.h>
1da177e4	17	#include <linux/security.h>
975d2943	18	#include <linux/evm.h>
9957a504	19	#include <linux/ima.h>
1da177e4	20
0031181c EB	21	static bool chown_ok(const struct inode *inode, kuid_t uid)
	22	{
	23	if (uid_eq(current_fsuid(), inode->i_uid) &&
	24	uid_eq(uid, inode->i_uid))
	25	return true;
	26	if (capable_wrt_inode_uidgid(inode, CAP_CHOWN))
	27	return true;
	28	if (uid_eq(inode->i_uid, INVALID_UID) &&
	29	ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
	30	return true;
	31	return false;
	32	}
	33
	34	static bool chgrp_ok(const struct inode *inode, kgid_t gid)
	35	{
	36	if (uid_eq(current_fsuid(), inode->i_uid) &&
	37	(in_group_p(gid) \|\| gid_eq(gid, inode->i_gid)))
	38	return true;
	39	if (capable_wrt_inode_uidgid(inode, CAP_CHOWN))
	40	return true;
	41	if (gid_eq(inode->i_gid, INVALID_GID) &&
	42	ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
	43	return true;
	44	return false;
	45	}
	46
2c27c65e	47	/**
31051c85 JK	48	* setattr_prepare - check if attribute changes to a dentry are allowed
31051c85 JK	49	* @dentry: dentry to check
2c27c65e CH	50	* @attr: attributes to change
	51	*
	52	* Check if we are allowed to change the attributes contained in @attr
31051c85 JK	53	* in the given dentry. This includes the normal unix access permission
	54	* checks, as well as checks for rlimits and others. The function also clears
	55	* SGID bit from mode if user is not allowed to set it. Also file capabilities
	56	* and IMA extended attributes are cleared if ATTR_KILL_PRIV is set.
2c27c65e CH	57	*
	58	* Should be called as the first thing in ->setattr implementations,
	59	* possibly after taking additional locks.
	60	*/
31051c85	61	int setattr_prepare(struct dentry dentry, struct iattr attr)
1da177e4	62	{
31051c85	63	struct inode *inode = d_inode(dentry);
1da177e4 LT	64	unsigned int ia_valid = attr->ia_valid;
1da177e4 LT	65
2c27c65e CH	66	/*
	67	* First check size constraints. These can't be overriden using
	68	* ATTR_FORCE.
	69	*/
	70	if (ia_valid & ATTR_SIZE) {
	71	int error = inode_newsize_ok(inode, attr->ia_size);
	72	if (error)
	73	return error;
	74	}
	75
1da177e4 LT	76	/* If force is set do it anyway. */
1da177e4 LT	77	if (ia_valid & ATTR_FORCE)
030b533c	78	goto kill_priv;
1da177e4 LT	79
1da177e4 LT	80	/* Make sure a caller can chown. */
0031181c	81	if ((ia_valid & ATTR_UID) && !chown_ok(inode, attr->ia_uid))
2c27c65e	82	return -EPERM;
1da177e4 LT	83
1da177e4 LT	84	/* Make sure caller can chgrp. */
0031181c	85	if ((ia_valid & ATTR_GID) && !chgrp_ok(inode, attr->ia_gid))
2c27c65e	86	return -EPERM;
1da177e4 LT	87
	88	/* Make sure a caller can chmod. */
	89	if (ia_valid & ATTR_MODE) {
2e149670	90	if (!inode_owner_or_capable(inode))
2c27c65e	91	return -EPERM;
1da177e4 LT	92	/* Also check the setgid bit! */
1da177e4 LT	93	if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
7fa294c8	94	inode->i_gid) &&
23adbe12	95	!capable_wrt_inode_uidgid(inode, CAP_FSETID))
1da177e4 LT	96	attr->ia_mode &= ~S_ISGID;
	97	}
	98
	99	/* Check for setting the inode time. */
9767d749	100	if (ia_valid & (ATTR_MTIME_SET \| ATTR_ATIME_SET \| ATTR_TIMES_SET)) {
2e149670	101	if (!inode_owner_or_capable(inode))
2c27c65e	102	return -EPERM;
1da177e4	103	}
2c27c65e	104
030b533c JK	105	kill_priv:
	106	/* User has permission for the change */
	107	if (ia_valid & ATTR_KILL_PRIV) {
	108	int error;
	109
	110	error = security_inode_killpriv(dentry);
	111	if (error)
	112	return error;
	113	}
	114
2c27c65e	115	return 0;
1da177e4	116	}
31051c85	117	EXPORT_SYMBOL(setattr_prepare);
1da177e4	118
25d9e2d1	119	/**
	120	* inode_newsize_ok - may this inode be truncated to a given size
	121	* @inode: the inode to be truncated
	122	* @offset: the new size to assign to the inode
25d9e2d1	123	*
7bb46a67	124	* inode_newsize_ok must be called with i_mutex held.
7bb46a67	125	*
25d9e2d1	126	* inode_newsize_ok will check filesystem limits and ulimits to check that the
	127	* new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
	128	* when necessary. Caller must not proceed with inode size change if failure is
	129	* returned. @inode must be a file (not directory), with appropriate
	130	* permissions to allow truncate (inode_newsize_ok does NOT check these
	131	* conditions).
3fae1746 MW	132	*
3fae1746 MW	133	* Return: 0 on success, -ve errno on failure
25d9e2d1	134	*/
	135	int inode_newsize_ok(const struct inode *inode, loff_t offset)
	136	{
	137	if (inode->i_size < offset) {
	138	unsigned long limit;
	139
d554ed89	140	limit = rlimit(RLIMIT_FSIZE);
25d9e2d1	141	if (limit != RLIM_INFINITY && offset > limit)
	142	goto out_sig;
	143	if (offset > inode->i_sb->s_maxbytes)
	144	goto out_big;
	145	} else {
	146	/*
	147	* truncation of in-use swapfiles is disallowed - it would
	148	* cause subsequent swapout to scribble on the now-freed
	149	* blocks.
	150	*/
	151	if (IS_SWAPFILE(inode))
	152	return -ETXTBSY;
	153	}
	154
	155	return 0;
	156	out_sig:
	157	send_sig(SIGXFSZ, current, 0);
	158	out_big:
	159	return -EFBIG;
	160	}
	161	EXPORT_SYMBOL(inode_newsize_ok);
	162
7bb46a67	163	/**
6a1a90ad	164	* setattr_copy - copy simple metadata updates into the generic inode
7bb46a67	165	* @inode: the inode to be updated
	166	* @attr: the new attributes
	167	*
6a1a90ad	168	* setattr_copy must be called with i_mutex held.
7bb46a67	169	*
6a1a90ad	170	* setattr_copy updates the inode's metadata with that specified
25985edc	171	* in attr. Noticeably missing is inode size update, which is more complex
2c27c65e	172	* as it requires pagecache updates.
7bb46a67	173	*
	174	* The inode is not marked as dirty after this operation. The rationale is
	175	* that for "simple" filesystems, the struct inode is the inode storage.
	176	* The caller is free to mark the inode dirty afterwards if needed.
	177	*/
6a1a90ad	178	void setattr_copy(struct inode inode, const struct iattr attr)
1da177e4 LT	179	{
1da177e4 LT	180	unsigned int ia_valid = attr->ia_valid;
4a30131e	181
1da177e4 LT	182	if (ia_valid & ATTR_UID)
	183	inode->i_uid = attr->ia_uid;
	184	if (ia_valid & ATTR_GID)
	185	inode->i_gid = attr->ia_gid;
	186	if (ia_valid & ATTR_ATIME)
95582b00 DD	187	inode->i_atime = timespec64_trunc(attr->ia_atime,
95582b00 DD	188	inode->i_sb->s_time_gran);
1da177e4	189	if (ia_valid & ATTR_MTIME)
95582b00 DD	190	inode->i_mtime = timespec64_trunc(attr->ia_mtime,
95582b00 DD	191	inode->i_sb->s_time_gran);
1da177e4	192	if (ia_valid & ATTR_CTIME)
95582b00 DD	193	inode->i_ctime = timespec64_trunc(attr->ia_ctime,
95582b00 DD	194	inode->i_sb->s_time_gran);
1da177e4 LT	195	if (ia_valid & ATTR_MODE) {
	196	umode_t mode = attr->ia_mode;
	197
7fa294c8	198	if (!in_group_p(inode->i_gid) &&
23adbe12	199	!capable_wrt_inode_uidgid(inode, CAP_FSETID))
1da177e4 LT	200	mode &= ~S_ISGID;
	201	inode->i_mode = mode;
	202	}
7bb46a67	203	}
6a1a90ad	204	EXPORT_SYMBOL(setattr_copy);
7bb46a67	205
27ac0ffe BF	206	/**
	207	* notify_change - modify attributes of a filesytem object
	208	* @dentry: object affected
3fae1746	209	* @attr: new attributes
27ac0ffe BF	210	* @delegated_inode: returns inode, if the inode is delegated
	211	*
	212	* The caller must hold the i_mutex on the affected object.
	213	*
	214	* If notify_change discovers a delegation in need of breaking,
	215	* it will return -EWOULDBLOCK and return a reference to the inode in
	216	* delegated_inode. The caller should then break the delegation and
	217	* retry. Because breaking a delegation may take a long time, the
	218	* caller should drop the i_mutex before doing so.
	219	*
	220	* Alternatively, a caller may pass NULL for delegated_inode. This may
	221	* be appropriate for callers that expect the underlying filesystem not
	222	* to be NFS exported. Also, passing NULL is fine for callers holding
	223	* the file open for write, as there can be no conflicting delegation in
	224	* that case.
	225	*/
	226	int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **delegated_inode)
1da177e4 LT	227	{
1da177e4 LT	228	struct inode *inode = dentry->d_inode;
8d334acd	229	umode_t mode = inode->i_mode;
1da177e4	230	int error;
95582b00	231	struct timespec64 now;
1da177e4 LT	232	unsigned int ia_valid = attr->ia_valid;
1da177e4 LT	233
5955102c	234	WARN_ON_ONCE(!inode_is_locked(inode));
c4107b30	235
beb29e05 MS	236	if (ia_valid & (ATTR_MODE \| ATTR_UID \| ATTR_GID \| ATTR_TIMES_SET)) {
	237	if (IS_IMMUTABLE(inode) \|\| IS_APPEND(inode))
	238	return -EPERM;
	239	}
	240
f2b20f6e MS	241	/*
	242	* If utimes(2) and friends are called with times == NULL (or both
	243	* times are UTIME_NOW), then we need to check for write permission
	244	*/
	245	if (ia_valid & ATTR_TOUCH) {
	246	if (IS_IMMUTABLE(inode))
	247	return -EPERM;
	248
	249	if (!inode_owner_or_capable(inode)) {
	250	error = inode_permission(inode, MAY_WRITE);
	251	if (error)
	252	return error;
	253	}
	254	}
	255
69b45732	256	if ((ia_valid & ATTR_MODE)) {
8d334acd	257	umode_t amode = attr->ia_mode;
69b45732 AK	258	/* Flag setting protected by i_mutex */
	259	if (is_sxid(amode))
	260	inode->i_flags &= ~S_NOSEC;
	261	}
	262
c2050a45	263	now = current_time(inode);
1da177e4 LT	264
	265	attr->ia_ctime = now;
	266	if (!(ia_valid & ATTR_ATIME_SET))
	267	attr->ia_atime = now;
	268	if (!(ia_valid & ATTR_MTIME_SET))
	269	attr->ia_mtime = now;
b5376771	270	if (ia_valid & ATTR_KILL_PRIV) {
b5376771	271	error = security_inode_need_killpriv(dentry);
030b533c	272	if (error < 0)
b5376771	273	return error;
030b533c JK	274	if (error == 0)
030b533c JK	275	ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV;
b5376771	276	}
6de0ec00 JL	277
	278	/*
	279	* We now pass ATTR_KILL_S*ID to the lower level setattr function so
	280	* that the function has the ability to reinterpret a mode change
	281	* that's due to these bits. This adds an implicit restriction that
	282	* no function will ever call notify_change with both ATTR_MODE and
	283	* ATTR_KILL_S*ID set.
	284	*/
	285	if ((ia_valid & (ATTR_KILL_SUID\|ATTR_KILL_SGID)) &&
	286	(ia_valid & ATTR_MODE))
	287	BUG();
	288
1da177e4	289	if (ia_valid & ATTR_KILL_SUID) {
1da177e4	290	if (mode & S_ISUID) {
6de0ec00 JL	291	ia_valid = attr->ia_valid \|= ATTR_MODE;
6de0ec00 JL	292	attr->ia_mode = (inode->i_mode & ~S_ISUID);
1da177e4 LT	293	}
	294	}
	295	if (ia_valid & ATTR_KILL_SGID) {
1da177e4 LT	296	if ((mode & (S_ISGID \| S_IXGRP)) == (S_ISGID \| S_IXGRP)) {
	297	if (!(ia_valid & ATTR_MODE)) {
	298	ia_valid = attr->ia_valid \|= ATTR_MODE;
	299	attr->ia_mode = inode->i_mode;
	300	}
	301	attr->ia_mode &= ~S_ISGID;
	302	}
	303	}
6de0ec00	304	if (!(attr->ia_valid & ~(ATTR_KILL_SUID \| ATTR_KILL_SGID)))
1da177e4 LT	305	return 0;
1da177e4 LT	306
a475acf0 SF	307	/*
	308	* Verify that uid/gid changes are valid in the target
	309	* namespace of the superblock.
	310	*/
	311	if (ia_valid & ATTR_UID &&
	312	!kuid_has_mapping(inode->i_sb->s_user_ns, attr->ia_uid))
	313	return -EOVERFLOW;
	314	if (ia_valid & ATTR_GID &&
	315	!kgid_has_mapping(inode->i_sb->s_user_ns, attr->ia_gid))
	316	return -EOVERFLOW;
	317
0bd23d09 EB	318	/* Don't allow modifications of files with invalid uids or
	319	* gids unless those uids & gids are being made valid.
	320	*/
	321	if (!(ia_valid & ATTR_UID) && !uid_valid(inode->i_uid))
	322	return -EOVERFLOW;
	323	if (!(ia_valid & ATTR_GID) && !gid_valid(inode->i_gid))
	324	return -EOVERFLOW;
	325
a77b72da	326	error = security_inode_setattr(dentry, attr);
27ac0ffe BF	327	if (error)
	328	return error;
	329	error = try_break_deleg(inode, delegated_inode);
a77b72da MS	330	if (error)
	331	return error;
	332
eef2380c	333	if (inode->i_op->setattr)
a77b72da	334	error = inode->i_op->setattr(dentry, attr);
eef2380c CH	335	else
eef2380c CH	336	error = simple_setattr(dentry, attr);
1da177e4	337
975d2943	338	if (!error) {
0eeca283	339	fsnotify_change(dentry, ia_valid);
9957a504	340	ima_inode_post_setattr(dentry);
975d2943 MZ	341	evm_inode_post_setattr(dentry, ia_valid);
975d2943 MZ	342	}
0eeca283	343
1da177e4 LT	344	return error;
1da177e4 LT	345	}
1da177e4	346	EXPORT_SYMBOL(notify_change);