[mirror_ubuntu-zesty-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>

/* Taken over from the old code... */

/* POSIX UID/GID verification for setting inode attributes. */
int inode_change_ok(const struct inode *inode, struct iattr *attr)
{
	int retval = -EPERM;
	unsigned int ia_valid = attr->ia_valid;

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

	/* 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))
		goto error;

	/* 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))
		goto error;

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