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Commit 77e69dac authored by Al Viro's avatar Al Viro
Browse files

[PATCH] fix races and leaks in vfs_quota_on() users 



* new helper: vfs_quota_on_path(); equivalent of vfs_quota_on() sans the
  pathname resolution.
* callers of vfs_quota_on() that do their own pathname resolution and
  checks based on it are switched to vfs_quota_on_path(); that way we
  avoid the races.
* reiserfs leaked dentry/vfsmount references on several failure exits.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 1b7e190b

fs/dquot.c

+20 −13
Original line number Diff line number Diff line
@@ -1793,6 +1793,21 @@ static int vfs_quota_on_remount(struct super_block *sb, int type) 
	return ret;

}



int vfs_quota_on_path(struct super_block *sb, int type, int format_id,

		      struct path *path)

{

	int error = security_quota_on(path->dentry);

	if (error)

		return error;

	/* Quota file not on the same filesystem? */

	if (path->mnt->mnt_sb != sb)

		error = -EXDEV;

	else

		error = vfs_quota_on_inode(path->dentry->d_inode, type,

					   format_id);

	return error;

}



/* Actual function called from quotactl() */

int vfs_quota_on(struct super_block *sb, int type, int format_id, char *path,

		 int remount)
@@ -1804,19 +1819,10 @@ int vfs_quota_on(struct super_block *sb, int type, int format_id, char *path, 
		return vfs_quota_on_remount(sb, type);



	error = path_lookup(path, LOOKUP_FOLLOW, &nd);

	if (error < 0)

		return error;

	error = security_quota_on(nd.path.dentry);

	if (error)

		goto out_path;

	/* Quota file not on the same filesystem? */

	if (nd.path.mnt->mnt_sb != sb)

		error = -EXDEV;

	else

		error = vfs_quota_on_inode(nd.path.dentry->d_inode, type,

					   format_id);

out_path:

	if (!error) {

		error = vfs_quota_on_path(sb, type, format_id, &nd.path);

		path_put(&nd.path);

	}

	return error;

}
@@ -2185,6 +2191,7 @@ EXPORT_SYMBOL(unregister_quota_format); 
EXPORT_SYMBOL(dqstats);

EXPORT_SYMBOL(dq_data_lock);

EXPORT_SYMBOL(vfs_quota_on);

EXPORT_SYMBOL(vfs_quota_on_path);

EXPORT_SYMBOL(vfs_quota_on_mount);

EXPORT_SYMBOL(vfs_quota_off);

EXPORT_SYMBOL(vfs_quota_sync);

fs/ext3/super.c

+2 −1
Original line number Diff line number Diff line
@@ -2810,8 +2810,9 @@ static int ext3_quota_on(struct super_block *sb, int type, int format_id, 
		journal_unlock_updates(EXT3_SB(sb)->s_journal);

	}



	err = vfs_quota_on_path(sb, type, format_id, &nd.path);

	path_put(&nd.path);

	return vfs_quota_on(sb, type, format_id, path, remount);

	return err;

}



/* Read data from quotafile - avoid pagecache and such because we cannot afford

fs/ext4/super.c

+2 −1
Original line number Diff line number Diff line
@@ -3352,8 +3352,9 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id, 
		jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);

	}



	err = vfs_quota_on_path(sb, type, format_id, &nd.path);

	path_put(&nd.path);

	return vfs_quota_on(sb, type, format_id, path, remount);

	return err;

}



/* Read data from quotafile - avoid pagecache and such because we cannot afford

fs/reiserfs/super.c

+9 −7
Original line number Diff line number Diff line
@@ -2076,8 +2076,8 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id, 
		return err;

	/* Quotafile not on the same filesystem? */

	if (nd.path.mnt->mnt_sb != sb) {

		path_put(&nd.path);

		return -EXDEV;

		err = -EXDEV;

		goto out;

	}

	inode = nd.path.dentry->d_inode;

	/* We must not pack tails for quota files on reiserfs for quota IO to work */
@@ -2087,8 +2087,8 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id, 
			reiserfs_warning(sb,

				"reiserfs: Unpacking tail of quota file failed"

				" (%d). Cannot turn on quotas.", err);

			path_put(&nd.path);

			return -EINVAL;

			err = -EINVAL;

			goto out;

		}

		mark_inode_dirty(inode);

	}
@@ -2109,13 +2109,15 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id, 
		/* Just start temporary transaction and finish it */

		err = journal_begin(&th, sb, 1);

		if (err)

			return err;

			goto out;

		err = journal_end_sync(&th, sb, 1);

		if (err)

			return err;

			goto out;

	}

	err = vfs_quota_on_path(sb, type, format_id, &nd.path);

out:

	path_put(&nd.path);

	return vfs_quota_on(sb, type, format_id, path, 0);

	return err;

}



/* Read data from quotafile - avoid pagecache and such because we cannot afford

include/linux/quotaops.h

+2 −0
Original line number Diff line number Diff line
@@ -43,6 +43,8 @@ int dquot_mark_dquot_dirty(struct dquot *dquot); 


int vfs_quota_on(struct super_block *sb, int type, int format_id,

 	char *path, int remount);

int vfs_quota_on_path(struct super_block *sb, int type, int format_id,

 	struct path *path);

int vfs_quota_on_mount(struct super_block *sb, char *qf_name,

 	int format_id, int type);

int vfs_quota_off(struct super_block *sb, int type, int remount);