Release 4.8 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>
#include <linux/ima.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) &&
	    (!uid_eq(current_fsuid(), inode->i_uid) ||
	     !uid_eq(attr->ia_uid, inode->i_uid)) &&
	    !capable_wrt_inode_uidgid(inode, CAP_CHOWN))
		return -EPERM;

	/* Make sure caller can chgrp. */
	if ((ia_valid & ATTR_GID) &&
	    (!uid_eq(current_fsuid(), inode->i_uid) ||
	    (!in_group_p(attr->ia_gid) && !gid_eq(attr->ia_gid, inode->i_gid))) &&
	    !capable_wrt_inode_uidgid(inode, 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_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;
	}

	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
pre-git
pre-git
157
62.55%
4
28.57%
christoph hellwig
christoph hellwig
48
19.12%
1
7.14%
eric w. biederman
eric w. biederman
26
10.36%
2
14.29%
chris wright
chris wright
6
2.39%
1
7.14%
david howells
david howells
4
1.59%
1
7.14%
andy lutomirski
andy lutomirski
3
1.20%
1
7.14%
serge hallyn
serge hallyn
2
0.80%
1
7.14%
satyam sharma
satyam sharma
2
0.80%
1
7.14%
miklos szeredi
miklos szeredi
2
0.80%
1
7.14%
nick piggin
nick piggin
1
0.40%
1
7.14%
Total
251
100.00%
14
100.00%


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;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
nick piggin
nick piggin
93
96.88%
1
50.00%
jiri slaby
jiri slaby
3
3.12%
1
50.00%
Total
96
100.00%
2
100.00%


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_wrt_inode_uidgid(inode, CAP_FSETID))
			mode &= ~S_ISGID;
		inode->i_mode = mode;
	}
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
pre-git
pre-git
112
67.88%
5
41.67%
andi kleen
andi kleen
27
16.36%
1
8.33%
andrew morton
andrew morton
11
6.67%
1
8.33%
linus torvalds
linus torvalds
8
4.85%
1
8.33%
nick piggin
nick piggin
3
1.82%
1
8.33%
eric w. biederman
eric w. biederman
2
1.21%
1
8.33%
andy lutomirski
andy lutomirski
1
0.61%
1
8.33%
christoph hellwig
christoph hellwig
1
0.61%
1
8.33%
Total
165
100.00%
12
100.00%


EXPORT_SYMBOL(setattr_copy);

/**
 * notify_change - modify attributes of a filesytem object
 * @dentry:     object affected
 * @iattr:      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 timespec 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 ((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;

	/*
         * 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;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
pre-git
pre-git
113
20.89%
6
21.43%
al viro
al viro
99
18.30%
4
14.29%
seth forshee
seth forshee
49
9.06%
1
3.57%
miklos szeredi
miklos szeredi
48
8.87%
2
7.14%
serge hallyn
serge hallyn
47
8.69%
1
3.57%
eric w. biederman
eric w. biederman
43
7.95%
1
3.57%
jeff layton
jeff layton
35
6.47%
1
3.57%
andi kleen
andi kleen
33
6.10%
2
7.14%
j. bruce fields
j. bruce fields
22
4.07%
1
3.57%
mimi zohar
mimi zohar
14
2.59%
2
7.14%
chuck lever
chuck lever
12
2.22%
1
3.57%
adrian bunk
adrian bunk
9
1.66%
1
3.57%
andrew morton
andrew morton
8
1.48%
1
3.57%
dave hansen
dave hansen
3
0.55%
1
3.57%
stephen d. smalley
stephen d. smalley
2
0.37%
1
3.57%
robert love
robert love
2
0.37%
1
3.57%
christoph hellwig
christoph hellwig
2
0.37%
1
3.57%
Total
541
100.00%
28
100.00%


EXPORT_SYMBOL(notify_change);
Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
pre-git
pre-git
396
35.74%
10
18.52%
nick piggin
nick piggin
107
9.66%
2
3.70%
al viro
al viro
99
8.94%
4
7.41%
eric w. biederman
eric w. biederman
71
6.41%
3
5.56%
andi kleen
andi kleen
60
5.42%
3
5.56%
christoph hellwig
christoph hellwig
53
4.78%
3
5.56%
miklos szeredi
miklos szeredi
50
4.51%
3
5.56%
serge hallyn
serge hallyn
49
4.42%
2
3.70%
seth forshee
seth forshee
49
4.42%
1
1.85%
jeff layton
jeff layton
35
3.16%
1
1.85%
j. bruce fields
j. bruce fields
23
2.08%
1
1.85%
mimi zohar
mimi zohar
20
1.81%
2
3.70%
andrew morton
andrew morton
19
1.71%
2
3.70%
arnaldo carvalho de melo
arnaldo carvalho de melo
12
1.08%
1
1.85%
chuck lever
chuck lever
12
1.08%
1
1.85%
linus torvalds
linus torvalds
10
0.90%
2
3.70%
adrian bunk
adrian bunk
9
0.81%
1
1.85%
chris wright
chris wright
6
0.54%
1
1.85%
david howells
david howells
4
0.36%
1
1.85%
andy lutomirski
andy lutomirski
4
0.36%
1
1.85%
stephen d. smalley
stephen d. smalley
3
0.27%
1
1.85%
randy dunlap
randy dunlap
3
0.27%
1
1.85%
jiri slaby
jiri slaby
3
0.27%
1
1.85%
robert love
robert love
3
0.27%
1
1.85%
dave hansen
dave hansen
3
0.27%
1
1.85%
satyam sharma
satyam sharma
2
0.18%
1
1.85%
paul gortmaker
paul gortmaker
1
0.09%
1
1.85%
lucas de marchi
lucas de marchi
1
0.09%
1
1.85%
dave jones
dave jones
1
0.09%
1
1.85%
Total
1108
100.00%
54
100.00%
  
Directory: fs

Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.