[mirror_ubuntu-jammy-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>

/**
 * chown_ok - verify permissions to chown inode
 * @mnt_userns:	user namespace of the mount @inode was found from
 * @inode:	inode to check permissions on
 * @uid:	uid to chown @inode to
 *
 * If the inode has been found through an idmapped mount the user namespace of
 * the vfsmount must be passed through @mnt_userns. This function will then
 * take care to map the inode according to @mnt_userns before checking
 * permissions. On non-idmapped mounts or if permission checking is to be
 * performed on the raw inode simply passs init_user_ns.
 */
static bool chown_ok(struct user_namespace *mnt_userns,
		     const struct inode *inode,
		     kuid_t uid)
{
	kuid_t kuid = i_uid_into_mnt(mnt_userns, inode);
	if (uid_eq(current_fsuid(), kuid) && uid_eq(uid, inode->i_uid))
		return true;
	if (capable_wrt_inode_uidgid(mnt_userns, inode, CAP_CHOWN))
		return true;
	if (uid_eq(kuid, INVALID_UID) &&
	    ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
		return true;
	return false;
}

/**
 * chgrp_ok - verify permissions to chgrp inode
 * @mnt_userns:	user namespace of the mount @inode was found from
 * @inode:	inode to check permissions on
 * @gid:	gid to chown @inode to
 *
 * If the inode has been found through an idmapped mount the user namespace of
 * the vfsmount must be passed through @mnt_userns. This function will then
 * take care to map the inode according to @mnt_userns before checking
 * permissions. On non-idmapped mounts or if permission checking is to be
 * performed on the raw inode simply passs init_user_ns.
 */
static bool chgrp_ok(struct user_namespace *mnt_userns,
		     const struct inode *inode, kgid_t gid)
{
	kgid_t kgid = i_gid_into_mnt(mnt_userns, inode);
	if (uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode)) &&
	    (in_group_p(gid) || gid_eq(gid, inode->i_gid)))
		return true;
	if (capable_wrt_inode_uidgid(mnt_userns, inode, CAP_CHOWN))
		return true;
	if (gid_eq(kgid, 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
 * @mnt_userns:	user namespace of the mount the inode was found from
 * @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.
 *
 * If the inode has been found through an idmapped mount the user namespace of
 * the vfsmount must be passed through @mnt_userns. This function will then
 * take care to map the inode according to @mnt_userns before checking
 * permissions. On non-idmapped mounts or if permission checking is to be
 * performed on the raw inode simply passs init_user_ns.
 *
 * Should be called as the first thing in ->setattr implementations,
 * possibly after taking additional locks.
 */
int setattr_prepare(struct user_namespace *mnt_userns, 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(mnt_userns, inode, attr->ia_uid))
		return -EPERM;

	/* Make sure caller can chgrp. */
	if ((ia_valid & ATTR_GID) && !chgrp_ok(mnt_userns, inode, attr->ia_gid))
		return -EPERM;

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

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

		error = security_inode_killpriv(mnt_userns, 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
 * @mnt_userns:	user namespace of the mount the inode was found from
 * @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 on idmapped mounts. If file ownership is changed setattr_copy
 * doesn't map ia_uid and ia_gid. It will asssume the caller has already
 * provided the intended values. Necessary permission checks to determine
 * whether or not the S_ISGID property needs to be removed are performed with
 * the correct idmapped mount permission helpers.
 * Noticeably missing is inode size update, which is more complex
 * as it requires pagecache updates.
 *
 * If the inode has been found through an idmapped mount the user namespace of
 * the vfsmount must be passed through @mnt_userns. This function will then
 * take care to map the inode according to @mnt_userns before checking
 * permissions. On non-idmapped mounts or if permission checking is to be
 * performed on the raw inode simply passs init_user_ns.
 *
 * 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 user_namespace *mnt_userns, 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 = attr->ia_atime;
	if (ia_valid & ATTR_MTIME)
		inode->i_mtime = attr->ia_mtime;
	if (ia_valid & ATTR_CTIME)
		inode->i_ctime = attr->ia_ctime;
	if (ia_valid & ATTR_MODE) {
		umode_t mode = attr->ia_mode;
		kgid_t kgid = i_gid_into_mnt(mnt_userns, inode);
		if (!in_group_p(kgid) &&
		    !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
			mode &= ~S_ISGID;
		inode->i_mode = mode;
	}
}
EXPORT_SYMBOL(setattr_copy);

int may_setattr(struct user_namespace *mnt_userns, struct inode *inode,
		unsigned int ia_valid)
{
	int error;

	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(mnt_userns, inode)) {
			error = inode_permission(mnt_userns, inode, MAY_WRITE);
			if (error)
				return error;
		}
	}
	return 0;
}
EXPORT_SYMBOL(may_setattr);

/**
 * notify_change - modify attributes of a filesytem object
 * @mnt_userns:	user namespace of the mount the inode was found from
 * @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.
 *
 * If file ownership is changed notify_change() doesn't map ia_uid and
 * ia_gid. It will asssume the caller has already provided the intended values.
 *
 * 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.
 *
 * If the inode has been found through an idmapped mount the user namespace of
 * the vfsmount must be passed through @mnt_userns. This function will then
 * take care to map the inode according to @mnt_userns before checking
 * permissions. On non-idmapped mounts or if permission checking is to be
 * performed on the raw inode simply passs init_user_ns.
 */
int notify_change(struct user_namespace *mnt_userns, 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));

	error = may_setattr(mnt_userns, inode, ia_valid);
	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;
	else
		attr->ia_atime = timestamp_truncate(attr->ia_atime, inode);
	if (!(ia_valid & ATTR_MTIME_SET))
		attr->ia_mtime = now;
	else
		attr->ia_mtime = timestamp_truncate(attr->ia_mtime, inode);

	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(i_uid_into_mnt(mnt_userns, inode)))
		return -EOVERFLOW;
	if (!(ia_valid & ATTR_GID) &&
	    !gid_valid(i_gid_into_mnt(mnt_userns, inode)))
		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(mnt_userns, dentry, attr);
	else
		error = simple_setattr(mnt_userns, dentry, attr);

	if (!error) {
		fsnotify_change(dentry, ia_valid);
		ima_inode_post_setattr(mnt_userns, 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
2f221d6f CB	21	/**
	22	* chown_ok - verify permissions to chown inode
	23	* @mnt_userns: user namespace of the mount @inode was found from
	24	* @inode: inode to check permissions on
	25	* @uid: uid to chown @inode to
	26	*
	27	* If the inode has been found through an idmapped mount the user namespace of
	28	* the vfsmount must be passed through @mnt_userns. This function will then
	29	* take care to map the inode according to @mnt_userns before checking
	30	* permissions. On non-idmapped mounts or if permission checking is to be
	31	* performed on the raw inode simply passs init_user_ns.
	32	*/
	33	static bool chown_ok(struct user_namespace *mnt_userns,
	34	const struct inode *inode,
	35	kuid_t uid)
0031181c	36	{
2f221d6f	37	kuid_t kuid = i_uid_into_mnt(mnt_userns, inode);
cb70dd7c	38	if (uid_eq(current_fsuid(), kuid) && uid_eq(uid, inode->i_uid))
0031181c	39	return true;
2f221d6f	40	if (capable_wrt_inode_uidgid(mnt_userns, inode, CAP_CHOWN))
0031181c	41	return true;
2f221d6f	42	if (uid_eq(kuid, INVALID_UID) &&
0031181c EB	43	ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
	44	return true;
	45	return false;
	46	}
	47
2f221d6f CB	48	/**
	49	* chgrp_ok - verify permissions to chgrp inode
	50	* @mnt_userns: user namespace of the mount @inode was found from
	51	* @inode: inode to check permissions on
	52	* @gid: gid to chown @inode to
	53	*
	54	* If the inode has been found through an idmapped mount the user namespace of
	55	* the vfsmount must be passed through @mnt_userns. This function will then
	56	* take care to map the inode according to @mnt_userns before checking
	57	* permissions. On non-idmapped mounts or if permission checking is to be
	58	* performed on the raw inode simply passs init_user_ns.
	59	*/
	60	static bool chgrp_ok(struct user_namespace *mnt_userns,
	61	const struct inode *inode, kgid_t gid)
0031181c	62	{
2f221d6f CB	63	kgid_t kgid = i_gid_into_mnt(mnt_userns, inode);
2f221d6f CB	64	if (uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode)) &&
cb70dd7c	65	(in_group_p(gid) \|\| gid_eq(gid, inode->i_gid)))
0031181c	66	return true;
2f221d6f	67	if (capable_wrt_inode_uidgid(mnt_userns, inode, CAP_CHOWN))
0031181c	68	return true;
2f221d6f	69	if (gid_eq(kgid, INVALID_GID) &&
0031181c EB	70	ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
	71	return true;
	72	return false;
	73	}
	74
2c27c65e	75	/**
31051c85	76	* setattr_prepare - check if attribute changes to a dentry are allowed
2f221d6f	77	* @mnt_userns: user namespace of the mount the inode was found from
31051c85	78	* @dentry: dentry to check
2c27c65e CH	79	* @attr: attributes to change
	80	*
	81	* Check if we are allowed to change the attributes contained in @attr
31051c85 JK	82	* in the given dentry. This includes the normal unix access permission
	83	* checks, as well as checks for rlimits and others. The function also clears
	84	* SGID bit from mode if user is not allowed to set it. Also file capabilities
	85	* and IMA extended attributes are cleared if ATTR_KILL_PRIV is set.
2c27c65e	86	*
2f221d6f CB	87	* If the inode has been found through an idmapped mount the user namespace of
	88	* the vfsmount must be passed through @mnt_userns. This function will then
	89	* take care to map the inode according to @mnt_userns before checking
	90	* permissions. On non-idmapped mounts or if permission checking is to be
	91	* performed on the raw inode simply passs init_user_ns.
	92	*
2c27c65e CH	93	* Should be called as the first thing in ->setattr implementations,
	94	* possibly after taking additional locks.
	95	*/
2f221d6f CB	96	int setattr_prepare(struct user_namespace mnt_userns, struct dentry dentry,
2f221d6f CB	97	struct iattr *attr)
1da177e4	98	{
31051c85	99	struct inode *inode = d_inode(dentry);
1da177e4 LT	100	unsigned int ia_valid = attr->ia_valid;
1da177e4 LT	101
2c27c65e CH	102	/*
	103	* First check size constraints. These can't be overriden using
	104	* ATTR_FORCE.
	105	*/
	106	if (ia_valid & ATTR_SIZE) {
	107	int error = inode_newsize_ok(inode, attr->ia_size);
	108	if (error)
	109	return error;
	110	}
	111
1da177e4 LT	112	/* If force is set do it anyway. */
1da177e4 LT	113	if (ia_valid & ATTR_FORCE)
030b533c	114	goto kill_priv;
1da177e4 LT	115
1da177e4 LT	116	/* Make sure a caller can chown. */
2f221d6f	117	if ((ia_valid & ATTR_UID) && !chown_ok(mnt_userns, inode, attr->ia_uid))
2c27c65e	118	return -EPERM;
1da177e4 LT	119
1da177e4 LT	120	/* Make sure caller can chgrp. */
2f221d6f	121	if ((ia_valid & ATTR_GID) && !chgrp_ok(mnt_userns, inode, attr->ia_gid))
2c27c65e	122	return -EPERM;
1da177e4 LT	123
	124	/* Make sure a caller can chmod. */
	125	if (ia_valid & ATTR_MODE) {
2f221d6f	126	if (!inode_owner_or_capable(mnt_userns, inode))
2c27c65e	127	return -EPERM;
1da177e4	128	/* Also check the setgid bit! */
2f221d6f CB	129	if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
	130	i_gid_into_mnt(mnt_userns, inode)) &&
	131	!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
1da177e4 LT	132	attr->ia_mode &= ~S_ISGID;
	133	}
	134
	135	/* Check for setting the inode time. */
9767d749	136	if (ia_valid & (ATTR_MTIME_SET \| ATTR_ATIME_SET \| ATTR_TIMES_SET)) {
2f221d6f	137	if (!inode_owner_or_capable(mnt_userns, inode))
2c27c65e	138	return -EPERM;
1da177e4	139	}
2c27c65e	140
030b533c JK	141	kill_priv:
	142	/* User has permission for the change */
	143	if (ia_valid & ATTR_KILL_PRIV) {
	144	int error;
	145
71bc356f	146	error = security_inode_killpriv(mnt_userns, dentry);
030b533c JK	147	if (error)
	148	return error;
	149	}
	150
2c27c65e	151	return 0;
1da177e4	152	}
31051c85	153	EXPORT_SYMBOL(setattr_prepare);
1da177e4	154
25d9e2d1 NP	155	/**
	156	* inode_newsize_ok - may this inode be truncated to a given size
	157	* @inode: the inode to be truncated
	158	* @offset: the new size to assign to the inode
25d9e2d1	159	*
7bb46a67 NP	160	* inode_newsize_ok must be called with i_mutex held.
7bb46a67 NP	161	*
25d9e2d1 NP	162	* inode_newsize_ok will check filesystem limits and ulimits to check that the
	163	* new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
	164	* when necessary. Caller must not proceed with inode size change if failure is
	165	* returned. @inode must be a file (not directory), with appropriate
	166	* permissions to allow truncate (inode_newsize_ok does NOT check these
	167	* conditions).
3fae1746 MW	168	*
3fae1746 MW	169	* Return: 0 on success, -ve errno on failure
25d9e2d1 NP	170	*/
	171	int inode_newsize_ok(const struct inode *inode, loff_t offset)
	172	{
	173	if (inode->i_size < offset) {
	174	unsigned long limit;
	175
d554ed89	176	limit = rlimit(RLIMIT_FSIZE);
25d9e2d1 NP	177	if (limit != RLIM_INFINITY && offset > limit)
	178	goto out_sig;
	179	if (offset > inode->i_sb->s_maxbytes)
	180	goto out_big;
	181	} else {
	182	/*
	183	* truncation of in-use swapfiles is disallowed - it would
	184	* cause subsequent swapout to scribble on the now-freed
	185	* blocks.
	186	*/
	187	if (IS_SWAPFILE(inode))
	188	return -ETXTBSY;
	189	}
	190
	191	return 0;
	192	out_sig:
	193	send_sig(SIGXFSZ, current, 0);
	194	out_big:
	195	return -EFBIG;
	196	}
	197	EXPORT_SYMBOL(inode_newsize_ok);
	198
7bb46a67	199	/**
6a1a90ad	200	* setattr_copy - copy simple metadata updates into the generic inode
2f221d6f	201	* @mnt_userns: user namespace of the mount the inode was found from
7bb46a67 NP	202	* @inode: the inode to be updated
	203	* @attr: the new attributes
	204	*
6a1a90ad	205	* setattr_copy must be called with i_mutex held.
7bb46a67	206	*
6a1a90ad	207	* setattr_copy updates the inode's metadata with that specified
2f221d6f CB	208	* in attr on idmapped mounts. If file ownership is changed setattr_copy
	209	* doesn't map ia_uid and ia_gid. It will asssume the caller has already
	210	* provided the intended values. Necessary permission checks to determine
	211	* whether or not the S_ISGID property needs to be removed are performed with
	212	* the correct idmapped mount permission helpers.
	213	* Noticeably missing is inode size update, which is more complex
2c27c65e	214	* as it requires pagecache updates.
7bb46a67	215	*
2f221d6f CB	216	* If the inode has been found through an idmapped mount the user namespace of
	217	* the vfsmount must be passed through @mnt_userns. This function will then
	218	* take care to map the inode according to @mnt_userns before checking
	219	* permissions. On non-idmapped mounts or if permission checking is to be
	220	* performed on the raw inode simply passs init_user_ns.
	221	*
7bb46a67 NP	222	* The inode is not marked as dirty after this operation. The rationale is
	223	* that for "simple" filesystems, the struct inode is the inode storage.
	224	* The caller is free to mark the inode dirty afterwards if needed.
	225	*/
2f221d6f CB	226	void setattr_copy(struct user_namespace mnt_userns, struct inode inode,
2f221d6f CB	227	const struct iattr *attr)
1da177e4 LT	228	{
1da177e4 LT	229	unsigned int ia_valid = attr->ia_valid;
4a30131e	230
1da177e4 LT	231	if (ia_valid & ATTR_UID)
	232	inode->i_uid = attr->ia_uid;
	233	if (ia_valid & ATTR_GID)
	234	inode->i_gid = attr->ia_gid;
eb31e2f6 AG	235	if (ia_valid & ATTR_ATIME)
	236	inode->i_atime = attr->ia_atime;
	237	if (ia_valid & ATTR_MTIME)
	238	inode->i_mtime = attr->ia_mtime;
	239	if (ia_valid & ATTR_CTIME)
	240	inode->i_ctime = attr->ia_ctime;
1da177e4 LT	241	if (ia_valid & ATTR_MODE) {
1da177e4 LT	242	umode_t mode = attr->ia_mode;
2f221d6f CB	243	kgid_t kgid = i_gid_into_mnt(mnt_userns, inode);
	244	if (!in_group_p(kgid) &&
	245	!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
1da177e4 LT	246	mode &= ~S_ISGID;
	247	inode->i_mode = mode;
	248	}
7bb46a67	249	}
6a1a90ad	250	EXPORT_SYMBOL(setattr_copy);
7bb46a67	251
7bb698f0 AG	252	int may_setattr(struct user_namespace mnt_userns, struct inode inode,
	253	unsigned int ia_valid)
	254	{
	255	int error;
	256
	257	if (ia_valid & (ATTR_MODE \| ATTR_UID \| ATTR_GID \| ATTR_TIMES_SET)) {
	258	if (IS_IMMUTABLE(inode) \|\| IS_APPEND(inode))
	259	return -EPERM;
	260	}
	261
	262	/*
	263	* If utimes(2) and friends are called with times == NULL (or both
	264	* times are UTIME_NOW), then we need to check for write permission
	265	*/
	266	if (ia_valid & ATTR_TOUCH) {
	267	if (IS_IMMUTABLE(inode))
	268	return -EPERM;
	269
	270	if (!inode_owner_or_capable(mnt_userns, inode)) {
	271	error = inode_permission(mnt_userns, inode, MAY_WRITE);
	272	if (error)
	273	return error;
	274	}
	275	}
	276	return 0;
	277	}
	278	EXPORT_SYMBOL(may_setattr);
	279
27ac0ffe BF	280	/**
27ac0ffe BF	281	* notify_change - modify attributes of a filesytem object
2f221d6f	282	* @mnt_userns: user namespace of the mount the inode was found from
27ac0ffe	283	* @dentry: object affected
3fae1746	284	* @attr: new attributes
27ac0ffe BF	285	* @delegated_inode: returns inode, if the inode is delegated
	286	*
	287	* The caller must hold the i_mutex on the affected object.
	288	*
	289	* If notify_change discovers a delegation in need of breaking,
	290	* it will return -EWOULDBLOCK and return a reference to the inode in
	291	* delegated_inode. The caller should then break the delegation and
	292	* retry. Because breaking a delegation may take a long time, the
	293	* caller should drop the i_mutex before doing so.
	294	*
2f221d6f CB	295	* If file ownership is changed notify_change() doesn't map ia_uid and
	296	* ia_gid. It will asssume the caller has already provided the intended values.
	297	*
27ac0ffe BF	298	* Alternatively, a caller may pass NULL for delegated_inode. This may
	299	* be appropriate for callers that expect the underlying filesystem not
	300	* to be NFS exported. Also, passing NULL is fine for callers holding
	301	* the file open for write, as there can be no conflicting delegation in
	302	* that case.
2f221d6f CB	303	*
	304	* If the inode has been found through an idmapped mount the user namespace of
	305	* the vfsmount must be passed through @mnt_userns. This function will then
	306	* take care to map the inode according to @mnt_userns before checking
	307	* permissions. On non-idmapped mounts or if permission checking is to be
	308	* performed on the raw inode simply passs init_user_ns.
27ac0ffe	309	*/
2f221d6f CB	310	int notify_change(struct user_namespace mnt_userns, struct dentry dentry,
2f221d6f CB	311	struct iattr attr, struct inode *delegated_inode)
1da177e4 LT	312	{
1da177e4 LT	313	struct inode *inode = dentry->d_inode;
8d334acd	314	umode_t mode = inode->i_mode;
1da177e4	315	int error;
95582b00	316	struct timespec64 now;
1da177e4 LT	317	unsigned int ia_valid = attr->ia_valid;
1da177e4 LT	318
5955102c	319	WARN_ON_ONCE(!inode_is_locked(inode));
c4107b30	320
7bb698f0 AG	321	error = may_setattr(mnt_userns, inode, ia_valid);
	322	if (error)
	323	return error;
f2b20f6e	324
69b45732	325	if ((ia_valid & ATTR_MODE)) {
8d334acd	326	umode_t amode = attr->ia_mode;
69b45732 AK	327	/* Flag setting protected by i_mutex */
	328	if (is_sxid(amode))
	329	inode->i_flags &= ~S_NOSEC;
	330	}
	331
c2050a45	332	now = current_time(inode);
1da177e4 LT	333
	334	attr->ia_ctime = now;
	335	if (!(ia_valid & ATTR_ATIME_SET))
	336	attr->ia_atime = now;
eb31e2f6 AG	337	else
eb31e2f6 AG	338	attr->ia_atime = timestamp_truncate(attr->ia_atime, inode);
1da177e4 LT	339	if (!(ia_valid & ATTR_MTIME_SET))
1da177e4 LT	340	attr->ia_mtime = now;
eb31e2f6 AG	341	else
	342	attr->ia_mtime = timestamp_truncate(attr->ia_mtime, inode);
	343
b5376771	344	if (ia_valid & ATTR_KILL_PRIV) {
b5376771	345	error = security_inode_need_killpriv(dentry);
030b533c	346	if (error < 0)
b5376771	347	return error;
030b533c JK	348	if (error == 0)
030b533c JK	349	ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV;
b5376771	350	}
6de0ec00 JL	351
	352	/*
	353	* We now pass ATTR_KILL_S*ID to the lower level setattr function so
	354	* that the function has the ability to reinterpret a mode change
	355	* that's due to these bits. This adds an implicit restriction that
	356	* no function will ever call notify_change with both ATTR_MODE and
	357	* ATTR_KILL_S*ID set.
	358	*/
	359	if ((ia_valid & (ATTR_KILL_SUID\|ATTR_KILL_SGID)) &&
	360	(ia_valid & ATTR_MODE))
	361	BUG();
	362
1da177e4	363	if (ia_valid & ATTR_KILL_SUID) {
1da177e4	364	if (mode & S_ISUID) {
6de0ec00 JL	365	ia_valid = attr->ia_valid \|= ATTR_MODE;
6de0ec00 JL	366	attr->ia_mode = (inode->i_mode & ~S_ISUID);
1da177e4 LT	367	}
	368	}
	369	if (ia_valid & ATTR_KILL_SGID) {
1da177e4 LT	370	if ((mode & (S_ISGID \| S_IXGRP)) == (S_ISGID \| S_IXGRP)) {
	371	if (!(ia_valid & ATTR_MODE)) {
	372	ia_valid = attr->ia_valid \|= ATTR_MODE;
	373	attr->ia_mode = inode->i_mode;
	374	}
	375	attr->ia_mode &= ~S_ISGID;
	376	}
	377	}
6de0ec00	378	if (!(attr->ia_valid & ~(ATTR_KILL_SUID \| ATTR_KILL_SGID)))
1da177e4 LT	379	return 0;
1da177e4 LT	380
a475acf0 SF	381	/*
	382	* Verify that uid/gid changes are valid in the target
	383	* namespace of the superblock.
	384	*/
	385	if (ia_valid & ATTR_UID &&
	386	!kuid_has_mapping(inode->i_sb->s_user_ns, attr->ia_uid))
	387	return -EOVERFLOW;
	388	if (ia_valid & ATTR_GID &&
	389	!kgid_has_mapping(inode->i_sb->s_user_ns, attr->ia_gid))
	390	return -EOVERFLOW;
	391
0bd23d09 EB	392	/* Don't allow modifications of files with invalid uids or
	393	* gids unless those uids & gids are being made valid.
	394	*/
2f221d6f CB	395	if (!(ia_valid & ATTR_UID) &&
2f221d6f CB	396	!uid_valid(i_uid_into_mnt(mnt_userns, inode)))
0bd23d09	397	return -EOVERFLOW;
2f221d6f CB	398	if (!(ia_valid & ATTR_GID) &&
2f221d6f CB	399	!gid_valid(i_gid_into_mnt(mnt_userns, inode)))
0bd23d09 EB	400	return -EOVERFLOW;
0bd23d09 EB	401
a77b72da	402	error = security_inode_setattr(dentry, attr);
27ac0ffe BF	403	if (error)
	404	return error;
	405	error = try_break_deleg(inode, delegated_inode);
a77b72da MS	406	if (error)
	407	return error;
	408
eef2380c	409	if (inode->i_op->setattr)
549c7297	410	error = inode->i_op->setattr(mnt_userns, dentry, attr);
eef2380c	411	else
549c7297	412	error = simple_setattr(mnt_userns, dentry, attr);
1da177e4	413
975d2943	414	if (!error) {
0eeca283	415	fsnotify_change(dentry, ia_valid);
a2d2329e	416	ima_inode_post_setattr(mnt_userns, dentry);
975d2943 MZ	417	evm_inode_post_setattr(dentry, ia_valid);
975d2943 MZ	418	}
0eeca283	419
1da177e4 LT	420	return error;
1da177e4 LT	421	}
1da177e4	422	EXPORT_SYMBOL(notify_change);