[linux.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>

/**
 * inode_change_ok - check if attribute changes to an inode are allowed
 * @inode:	inode to check
 * @attr:	attributes to change
 *
 * Check if we are allowed to change the attributes contained in @attr
 * in the given inode.  This includes the normal unix access permission
 * checks, as well as checks for rlimits and others.
 *
 * Should be called as the first thing in ->setattr implementations,
 * possibly after taking additional locks.
 */
int inode_change_ok(const struct inode *inode, struct iattr *attr)
{
	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)
		return 0;

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

	/* Make sure caller can chgrp. */
	if ((ia_valid & ATTR_GID) &&
	    (current_fsuid() != inode->i_uid ||
	    (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
	    !capable(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(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;
	}

	return 0;
}
EXPORT_SYMBOL(inode_change_ok);

/**
 * 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(CAP_FSETID))
			mode &= ~S_ISGID;
		inode->i_mode = mode;
	}
}
EXPORT_SYMBOL(setattr_copy);

int notify_change(struct dentry * dentry, struct iattr * attr)
{
	struct inode *inode = dentry->d_inode;
	umode_t mode = inode->i_mode;
	int error;
	struct timespec now;
	unsigned int ia_valid = attr->ia_valid;

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

	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_fs_time(inode->i_sb);

	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) {
		attr->ia_valid &= ~ATTR_KILL_PRIV;
		ia_valid &= ~ATTR_KILL_PRIV;
		error = security_inode_need_killpriv(dentry);
		if (error > 0)
			error = security_inode_killpriv(dentry);
		if (error)
			return error;
	}

	/*
	 * 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;

	error = security_inode_setattr(dentry, attr);
	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);
		evm_inode_post_setattr(dentry, ia_valid);
	}

	return error;
}

EXPORT_SYMBOL(notify_change);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/attr.c
	3	*
	4	* Copyright (C) 1991, 1992 Linus Torvalds
	5	* changes by Thomas Schoebel-Theuer
	6	*/
	7
630d9c47	8	#include <linux/export.h>
1da177e4 LT	9	#include <linux/time.h>
	10	#include <linux/mm.h>
	11	#include <linux/string.h>
16f7e0fe	12	#include <linux/capability.h>
0eeca283	13	#include <linux/fsnotify.h>
1da177e4	14	#include <linux/fcntl.h>
1da177e4	15	#include <linux/security.h>
975d2943	16	#include <linux/evm.h>
1da177e4	17
2c27c65e CH	18	/**
	19	* inode_change_ok - check if attribute changes to an inode are allowed
	20	* @inode: inode to check
	21	* @attr: attributes to change
	22	*
	23	* Check if we are allowed to change the attributes contained in @attr
	24	* in the given inode. This includes the normal unix access permission
	25	* checks, as well as checks for rlimits and others.
	26	*
	27	* Should be called as the first thing in ->setattr implementations,
	28	* possibly after taking additional locks.
	29	*/
25d9e2d1	30	int inode_change_ok(const struct inode inode, struct iattr attr)
1da177e4	31	{
1da177e4 LT	32	unsigned int ia_valid = attr->ia_valid;
1da177e4 LT	33
2c27c65e CH	34	/*
	35	* First check size constraints. These can't be overriden using
	36	* ATTR_FORCE.
	37	*/
	38	if (ia_valid & ATTR_SIZE) {
	39	int error = inode_newsize_ok(inode, attr->ia_size);
	40	if (error)
	41	return error;
	42	}
	43
1da177e4 LT	44	/* If force is set do it anyway. */
1da177e4 LT	45	if (ia_valid & ATTR_FORCE)
2c27c65e	46	return 0;
1da177e4 LT	47
	48	/* Make sure a caller can chown. */
	49	if ((ia_valid & ATTR_UID) &&
da9592ed	50	(current_fsuid() != inode->i_uid \|\|
1da177e4	51	attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
2c27c65e	52	return -EPERM;
1da177e4 LT	53
	54	/* Make sure caller can chgrp. */
	55	if ((ia_valid & ATTR_GID) &&
da9592ed	56	(current_fsuid() != inode->i_uid \|\|
1da177e4 LT	57	(!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
1da177e4 LT	58	!capable(CAP_CHOWN))
2c27c65e	59	return -EPERM;
1da177e4 LT	60
	61	/* Make sure a caller can chmod. */
	62	if (ia_valid & ATTR_MODE) {
2e149670	63	if (!inode_owner_or_capable(inode))
2c27c65e	64	return -EPERM;
1da177e4 LT	65	/* Also check the setgid bit! */
	66	if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
	67	inode->i_gid) && !capable(CAP_FSETID))
	68	attr->ia_mode &= ~S_ISGID;
	69	}
	70
	71	/* Check for setting the inode time. */
9767d749	72	if (ia_valid & (ATTR_MTIME_SET \| ATTR_ATIME_SET \| ATTR_TIMES_SET)) {
2e149670	73	if (!inode_owner_or_capable(inode))
2c27c65e	74	return -EPERM;
1da177e4	75	}
2c27c65e CH	76
2c27c65e CH	77	return 0;
1da177e4	78	}
1da177e4 LT	79	EXPORT_SYMBOL(inode_change_ok);
1da177e4 LT	80
25d9e2d1 NP	81	/**
	82	* inode_newsize_ok - may this inode be truncated to a given size
	83	* @inode: the inode to be truncated
	84	* @offset: the new size to assign to the inode
	85	* @Returns: 0 on success, -ve errno on failure
	86	*
7bb46a67 NP	87	* inode_newsize_ok must be called with i_mutex held.
7bb46a67 NP	88	*
25d9e2d1 NP	89	* inode_newsize_ok will check filesystem limits and ulimits to check that the
	90	* new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
	91	* when necessary. Caller must not proceed with inode size change if failure is
	92	* returned. @inode must be a file (not directory), with appropriate
	93	* permissions to allow truncate (inode_newsize_ok does NOT check these
	94	* conditions).
25d9e2d1 NP	95	*/
	96	int inode_newsize_ok(const struct inode *inode, loff_t offset)
	97	{
	98	if (inode->i_size < offset) {
	99	unsigned long limit;
	100
d554ed89	101	limit = rlimit(RLIMIT_FSIZE);
25d9e2d1 NP	102	if (limit != RLIM_INFINITY && offset > limit)
	103	goto out_sig;
	104	if (offset > inode->i_sb->s_maxbytes)
	105	goto out_big;
	106	} else {
	107	/*
	108	* truncation of in-use swapfiles is disallowed - it would
	109	* cause subsequent swapout to scribble on the now-freed
	110	* blocks.
	111	*/
	112	if (IS_SWAPFILE(inode))
	113	return -ETXTBSY;
	114	}
	115
	116	return 0;
	117	out_sig:
	118	send_sig(SIGXFSZ, current, 0);
	119	out_big:
	120	return -EFBIG;
	121	}
	122	EXPORT_SYMBOL(inode_newsize_ok);
	123
7bb46a67	124	/**
6a1a90ad	125	* setattr_copy - copy simple metadata updates into the generic inode
7bb46a67 NP	126	* @inode: the inode to be updated
	127	* @attr: the new attributes
	128	*
6a1a90ad	129	* setattr_copy must be called with i_mutex held.
7bb46a67	130	*
6a1a90ad	131	* setattr_copy updates the inode's metadata with that specified
25985edc	132	* in attr. Noticeably missing is inode size update, which is more complex
2c27c65e	133	* as it requires pagecache updates.
7bb46a67 NP	134	*
	135	* The inode is not marked as dirty after this operation. The rationale is
	136	* that for "simple" filesystems, the struct inode is the inode storage.
	137	* The caller is free to mark the inode dirty afterwards if needed.
	138	*/
6a1a90ad	139	void setattr_copy(struct inode inode, const struct iattr attr)
1da177e4 LT	140	{
1da177e4 LT	141	unsigned int ia_valid = attr->ia_valid;
4a30131e	142
1da177e4 LT	143	if (ia_valid & ATTR_UID)
	144	inode->i_uid = attr->ia_uid;
	145	if (ia_valid & ATTR_GID)
	146	inode->i_gid = attr->ia_gid;
	147	if (ia_valid & ATTR_ATIME)
	148	inode->i_atime = timespec_trunc(attr->ia_atime,
	149	inode->i_sb->s_time_gran);
	150	if (ia_valid & ATTR_MTIME)
	151	inode->i_mtime = timespec_trunc(attr->ia_mtime,
	152	inode->i_sb->s_time_gran);
	153	if (ia_valid & ATTR_CTIME)
	154	inode->i_ctime = timespec_trunc(attr->ia_ctime,
	155	inode->i_sb->s_time_gran);
	156	if (ia_valid & ATTR_MODE) {
	157	umode_t mode = attr->ia_mode;
	158
	159	if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
	160	mode &= ~S_ISGID;
	161	inode->i_mode = mode;
	162	}
7bb46a67	163	}
6a1a90ad	164	EXPORT_SYMBOL(setattr_copy);
7bb46a67	165
1da177e4 LT	166	int notify_change(struct dentry * dentry, struct iattr * attr)
	167	{
	168	struct inode *inode = dentry->d_inode;
8d334acd	169	umode_t mode = inode->i_mode;
1da177e4 LT	170	int error;
	171	struct timespec now;
	172	unsigned int ia_valid = attr->ia_valid;
	173
beb29e05 MS	174	if (ia_valid & (ATTR_MODE \| ATTR_UID \| ATTR_GID \| ATTR_TIMES_SET)) {
	175	if (IS_IMMUTABLE(inode) \|\| IS_APPEND(inode))
	176	return -EPERM;
	177	}
	178
69b45732	179	if ((ia_valid & ATTR_MODE)) {
8d334acd	180	umode_t amode = attr->ia_mode;
69b45732 AK	181	/* Flag setting protected by i_mutex */
	182	if (is_sxid(amode))
	183	inode->i_flags &= ~S_NOSEC;
	184	}
	185
1da177e4 LT	186	now = current_fs_time(inode->i_sb);
	187
	188	attr->ia_ctime = now;
	189	if (!(ia_valid & ATTR_ATIME_SET))
	190	attr->ia_atime = now;
	191	if (!(ia_valid & ATTR_MTIME_SET))
	192	attr->ia_mtime = now;
b5376771 SH	193	if (ia_valid & ATTR_KILL_PRIV) {
	194	attr->ia_valid &= ~ATTR_KILL_PRIV;
	195	ia_valid &= ~ATTR_KILL_PRIV;
	196	error = security_inode_need_killpriv(dentry);
	197	if (error > 0)
	198	error = security_inode_killpriv(dentry);
	199	if (error)
	200	return error;
	201	}
6de0ec00 JL	202
	203	/*
	204	* We now pass ATTR_KILL_S*ID to the lower level setattr function so
	205	* that the function has the ability to reinterpret a mode change
	206	* that's due to these bits. This adds an implicit restriction that
	207	* no function will ever call notify_change with both ATTR_MODE and
	208	* ATTR_KILL_S*ID set.
	209	*/
	210	if ((ia_valid & (ATTR_KILL_SUID\|ATTR_KILL_SGID)) &&
	211	(ia_valid & ATTR_MODE))
	212	BUG();
	213
1da177e4	214	if (ia_valid & ATTR_KILL_SUID) {
1da177e4	215	if (mode & S_ISUID) {
6de0ec00 JL	216	ia_valid = attr->ia_valid \|= ATTR_MODE;
6de0ec00 JL	217	attr->ia_mode = (inode->i_mode & ~S_ISUID);
1da177e4 LT	218	}
	219	}
	220	if (ia_valid & ATTR_KILL_SGID) {
1da177e4 LT	221	if ((mode & (S_ISGID \| S_IXGRP)) == (S_ISGID \| S_IXGRP)) {
	222	if (!(ia_valid & ATTR_MODE)) {
	223	ia_valid = attr->ia_valid \|= ATTR_MODE;
	224	attr->ia_mode = inode->i_mode;
	225	}
	226	attr->ia_mode &= ~S_ISGID;
	227	}
	228	}
6de0ec00	229	if (!(attr->ia_valid & ~(ATTR_KILL_SUID \| ATTR_KILL_SGID)))
1da177e4 LT	230	return 0;
1da177e4 LT	231
a77b72da MS	232	error = security_inode_setattr(dentry, attr);
	233	if (error)
	234	return error;
	235
eef2380c	236	if (inode->i_op->setattr)
a77b72da	237	error = inode->i_op->setattr(dentry, attr);
eef2380c CH	238	else
eef2380c CH	239	error = simple_setattr(dentry, attr);
1da177e4	240
975d2943	241	if (!error) {
0eeca283	242	fsnotify_change(dentry, ia_valid);
975d2943 MZ	243	evm_inode_post_setattr(dentry, ia_valid);
975d2943 MZ	244	}
0eeca283	245
1da177e4 LT	246	return error;
	247	}
	248
	249	EXPORT_SYMBOL(notify_change);