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

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

#include <linux/module.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>

/**
 * 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 (!is_owner_or_cap(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 (!is_owner_or_cap(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. Noticably 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;
	mode_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;
	}

	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 (ia_valid & ATTR_SIZE)
		down_write(&dentry->d_inode->i_alloc_sem);

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

	if (ia_valid & ATTR_SIZE)
		up_write(&dentry->d_inode->i_alloc_sem);

	if (!error)
		fsnotify_change(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
	8	#include <linux/module.h>
	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>
1da177e4	16
2c27c65e CH	17	/**
	18	* inode_change_ok - check if attribute changes to an inode are allowed
	19	* @inode: inode to check
	20	* @attr: attributes to change
	21	*
	22	* Check if we are allowed to change the attributes contained in @attr
	23	* in the given inode. This includes the normal unix access permission
	24	* checks, as well as checks for rlimits and others.
	25	*
	26	* Should be called as the first thing in ->setattr implementations,
	27	* possibly after taking additional locks.
	28	*/
25d9e2d1	29	int inode_change_ok(const struct inode inode, struct iattr attr)
1da177e4	30	{
1da177e4 LT	31	unsigned int ia_valid = attr->ia_valid;
1da177e4 LT	32
2c27c65e CH	33	/*
	34	* First check size constraints. These can't be overriden using
	35	* ATTR_FORCE.
	36	*/
	37	if (ia_valid & ATTR_SIZE) {
	38	int error = inode_newsize_ok(inode, attr->ia_size);
	39	if (error)
	40	return error;
	41	}
	42
1da177e4 LT	43	/* If force is set do it anyway. */
1da177e4 LT	44	if (ia_valid & ATTR_FORCE)
2c27c65e	45	return 0;
1da177e4 LT	46
	47	/* Make sure a caller can chown. */
	48	if ((ia_valid & ATTR_UID) &&
da9592ed	49	(current_fsuid() != inode->i_uid \|\|
1da177e4	50	attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
2c27c65e	51	return -EPERM;
1da177e4 LT	52
	53	/* Make sure caller can chgrp. */
	54	if ((ia_valid & ATTR_GID) &&
da9592ed	55	(current_fsuid() != inode->i_uid \|\|
1da177e4 LT	56	(!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
1da177e4 LT	57	!capable(CAP_CHOWN))
2c27c65e	58	return -EPERM;
1da177e4 LT	59
	60	/* Make sure a caller can chmod. */
	61	if (ia_valid & ATTR_MODE) {
3bd858ab	62	if (!is_owner_or_cap(inode))
2c27c65e	63	return -EPERM;
1da177e4 LT	64	/* Also check the setgid bit! */
	65	if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
	66	inode->i_gid) && !capable(CAP_FSETID))
	67	attr->ia_mode &= ~S_ISGID;
	68	}
	69
	70	/* Check for setting the inode time. */
9767d749	71	if (ia_valid & (ATTR_MTIME_SET \| ATTR_ATIME_SET \| ATTR_TIMES_SET)) {
3bd858ab	72	if (!is_owner_or_cap(inode))
2c27c65e	73	return -EPERM;
1da177e4	74	}
2c27c65e CH	75
2c27c65e CH	76	return 0;
1da177e4	77	}
1da177e4 LT	78	EXPORT_SYMBOL(inode_change_ok);
1da177e4 LT	79
25d9e2d1	80	/**
	81	* inode_newsize_ok - may this inode be truncated to a given size
	82	* @inode: the inode to be truncated
	83	* @offset: the new size to assign to the inode
	84	* @Returns: 0 on success, -ve errno on failure
	85	*
7bb46a67	86	* inode_newsize_ok must be called with i_mutex held.
7bb46a67	87	*
25d9e2d1	88	* inode_newsize_ok will check filesystem limits and ulimits to check that the
	89	* new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
	90	* when necessary. Caller must not proceed with inode size change if failure is
	91	* returned. @inode must be a file (not directory), with appropriate
	92	* permissions to allow truncate (inode_newsize_ok does NOT check these
	93	* conditions).
25d9e2d1	94	*/
	95	int inode_newsize_ok(const struct inode *inode, loff_t offset)
	96	{
	97	if (inode->i_size < offset) {
	98	unsigned long limit;
	99
d554ed89	100	limit = rlimit(RLIMIT_FSIZE);
25d9e2d1	101	if (limit != RLIM_INFINITY && offset > limit)
	102	goto out_sig;
	103	if (offset > inode->i_sb->s_maxbytes)
	104	goto out_big;
	105	} else {
	106	/*
	107	* truncation of in-use swapfiles is disallowed - it would
	108	* cause subsequent swapout to scribble on the now-freed
	109	* blocks.
	110	*/
	111	if (IS_SWAPFILE(inode))
	112	return -ETXTBSY;
	113	}
	114
	115	return 0;
	116	out_sig:
	117	send_sig(SIGXFSZ, current, 0);
	118	out_big:
	119	return -EFBIG;
	120	}
	121	EXPORT_SYMBOL(inode_newsize_ok);
	122
7bb46a67	123	/**
6a1a90ad	124	* setattr_copy - copy simple metadata updates into the generic inode
7bb46a67	125	* @inode: the inode to be updated
	126	* @attr: the new attributes
	127	*
6a1a90ad	128	* setattr_copy must be called with i_mutex held.
7bb46a67	129	*
6a1a90ad	130	* setattr_copy updates the inode's metadata with that specified
7bb46a67	131	* in attr. Noticably missing is inode size update, which is more complex
2c27c65e	132	* as it requires pagecache updates.
7bb46a67	133	*
	134	* The inode is not marked as dirty after this operation. The rationale is
	135	* that for "simple" filesystems, the struct inode is the inode storage.
	136	* The caller is free to mark the inode dirty afterwards if needed.
	137	*/
6a1a90ad	138	void setattr_copy(struct inode inode, const struct iattr attr)
1da177e4 LT	139	{
1da177e4 LT	140	unsigned int ia_valid = attr->ia_valid;
4a30131e	141
1da177e4 LT	142	if (ia_valid & ATTR_UID)
	143	inode->i_uid = attr->ia_uid;
	144	if (ia_valid & ATTR_GID)
	145	inode->i_gid = attr->ia_gid;
	146	if (ia_valid & ATTR_ATIME)
	147	inode->i_atime = timespec_trunc(attr->ia_atime,
	148	inode->i_sb->s_time_gran);
	149	if (ia_valid & ATTR_MTIME)
	150	inode->i_mtime = timespec_trunc(attr->ia_mtime,
	151	inode->i_sb->s_time_gran);
	152	if (ia_valid & ATTR_CTIME)
	153	inode->i_ctime = timespec_trunc(attr->ia_ctime,
	154	inode->i_sb->s_time_gran);
	155	if (ia_valid & ATTR_MODE) {
	156	umode_t mode = attr->ia_mode;
	157
	158	if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
	159	mode &= ~S_ISGID;
	160	inode->i_mode = mode;
	161	}
7bb46a67	162	}
6a1a90ad	163	EXPORT_SYMBOL(setattr_copy);
7bb46a67	164
1da177e4 LT	165	int notify_change(struct dentry * dentry, struct iattr * attr)
	166	{
	167	struct inode *inode = dentry->d_inode;
6de0ec00	168	mode_t mode = inode->i_mode;
1da177e4 LT	169	int error;
	170	struct timespec now;
	171	unsigned int ia_valid = attr->ia_valid;
	172
beb29e05 MS	173	if (ia_valid & (ATTR_MODE \| ATTR_UID \| ATTR_GID \| ATTR_TIMES_SET)) {
	174	if (IS_IMMUTABLE(inode) \|\| IS_APPEND(inode))
	175	return -EPERM;
	176	}
	177
1da177e4 LT	178	now = current_fs_time(inode->i_sb);
	179
	180	attr->ia_ctime = now;
	181	if (!(ia_valid & ATTR_ATIME_SET))
	182	attr->ia_atime = now;
	183	if (!(ia_valid & ATTR_MTIME_SET))
	184	attr->ia_mtime = now;
b5376771 SH	185	if (ia_valid & ATTR_KILL_PRIV) {
	186	attr->ia_valid &= ~ATTR_KILL_PRIV;
	187	ia_valid &= ~ATTR_KILL_PRIV;
	188	error = security_inode_need_killpriv(dentry);
	189	if (error > 0)
	190	error = security_inode_killpriv(dentry);
	191	if (error)
	192	return error;
	193	}
6de0ec00 JL	194
	195	/*
	196	* We now pass ATTR_KILL_S*ID to the lower level setattr function so
	197	* that the function has the ability to reinterpret a mode change
	198	* that's due to these bits. This adds an implicit restriction that
	199	* no function will ever call notify_change with both ATTR_MODE and
	200	* ATTR_KILL_S*ID set.
	201	*/
	202	if ((ia_valid & (ATTR_KILL_SUID\|ATTR_KILL_SGID)) &&
	203	(ia_valid & ATTR_MODE))
	204	BUG();
	205
1da177e4	206	if (ia_valid & ATTR_KILL_SUID) {
1da177e4	207	if (mode & S_ISUID) {
6de0ec00 JL	208	ia_valid = attr->ia_valid \|= ATTR_MODE;
6de0ec00 JL	209	attr->ia_mode = (inode->i_mode & ~S_ISUID);
1da177e4 LT	210	}
	211	}
	212	if (ia_valid & ATTR_KILL_SGID) {
1da177e4 LT	213	if ((mode & (S_ISGID \| S_IXGRP)) == (S_ISGID \| S_IXGRP)) {
	214	if (!(ia_valid & ATTR_MODE)) {
	215	ia_valid = attr->ia_valid \|= ATTR_MODE;
	216	attr->ia_mode = inode->i_mode;
	217	}
	218	attr->ia_mode &= ~S_ISGID;
	219	}
	220	}
6de0ec00	221	if (!(attr->ia_valid & ~(ATTR_KILL_SUID \| ATTR_KILL_SGID)))
1da177e4 LT	222	return 0;
1da177e4 LT	223
a77b72da MS	224	error = security_inode_setattr(dentry, attr);
	225	if (error)
	226	return error;
	227
1da177e4 LT	228	if (ia_valid & ATTR_SIZE)
	229	down_write(&dentry->d_inode->i_alloc_sem);
	230
eef2380c	231	if (inode->i_op->setattr)
a77b72da	232	error = inode->i_op->setattr(dentry, attr);
eef2380c CH	233	else
eef2380c CH	234	error = simple_setattr(dentry, attr);
1da177e4 LT	235
	236	if (ia_valid & ATTR_SIZE)
	237	up_write(&dentry->d_inode->i_alloc_sem);
	238
0eeca283 RL	239	if (!error)
	240	fsnotify_change(dentry, ia_valid);
	241
1da177e4 LT	242	return error;
	243	}
	244
	245	EXPORT_SYMBOL(notify_change);