Commit a65001e8 authored by Al Viro's avatar Al Viro
Browse files

btrfs: sanitize security_mnt_opts use 



1) keeping a copy in btrfs_fs_info is completely pointless - we never
use it for anything.  Getting rid of that allows for simpler calling
conventions for setup_security_options() (caller is responsible for
freeing mnt_opts in all cases).

2) on remount we want to use ->sb_remount(), not ->sb_set_mnt_opts(),
same as we would if not for FS_BINARY_MOUNTDATA.  Behaviours *are*
close (in fact, selinux sb_set_mnt_opts() ought to punt to
sb_remount() in "already initialized" case), but let's handle
that uniformly.  And the only reason why the original btrfs changes
didn't go for security_sb_remount() in btrfs_remount() case is that
it hadn't been exported.  Let's export it for a while - it'll be
going away soon anyway.

Reviewed-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 8d64124a

fs/btrfs/ctree.h

+0 −4
Original line number Diff line number Diff line
@@ -1100,9 +1100,6 @@ struct btrfs_fs_info { 
	struct mutex unused_bg_unpin_mutex;

	struct mutex delete_unused_bgs_mutex;



	/* For btrfs to record security options */

	struct security_mnt_opts security_opts;



	/*

	 * Chunks that can't be freed yet (under a trim/discard operation)

	 * and will be latter freed. Protected by fs_info->chunk_mutex.
@@ -2959,7 +2956,6 @@ static inline void free_fs_info(struct btrfs_fs_info *fs_info) 
	kfree(fs_info->free_space_root);

	kfree(fs_info->super_copy);

	kfree(fs_info->super_for_commit);

	security_free_mnt_opts(&fs_info->security_opts);

	kvfree(fs_info);

}

fs/btrfs/super.c

+9 −54
Original line number Diff line number Diff line
@@ -1458,43 +1458,6 @@ out: 
	return root;

}



static int parse_security_options(char *orig_opts,

				  struct security_mnt_opts *sec_opts)

{

	return security_sb_eat_lsm_opts(orig_opts, sec_opts);

}



static int setup_security_options(struct btrfs_fs_info *fs_info,

				  struct super_block *sb,

				  struct security_mnt_opts *sec_opts)

{

	int ret = 0;



	/*

	 * Call security_sb_set_mnt_opts() to check whether new sec_opts

	 * is valid.

	 */

	ret = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);

	if (ret)

		return ret;



#ifdef CONFIG_SECURITY

	if (!fs_info->security_opts.num_mnt_opts) {

		/* first time security setup, copy sec_opts to fs_info */

		memcpy(&fs_info->security_opts, sec_opts, sizeof(*sec_opts));

	} else {

		/*

		 * Since SELinux (the only one supporting security_mnt_opts)

		 * does NOT support changing context during remount/mount of

		 * the same sb, this must be the same or part of the same

		 * security options, just free it.

		 */

		security_free_mnt_opts(sec_opts);

	}

#endif

	return ret;

}



/*

 * Find a superblock for the given device / mount point.

 *
@@ -1518,7 +1481,7 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type, 


	security_init_mnt_opts(&new_sec_opts);

	if (data) {

		error = parse_security_options(data, &new_sec_opts);

		error = security_sb_eat_lsm_opts(data, &new_sec_opts);

		if (error)

			return ERR_PTR(error);

	}
@@ -1537,7 +1500,6 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type, 


	fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);

	fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);

	security_init_mnt_opts(&fs_info->security_opts);

	if (!fs_info->super_copy || !fs_info->super_for_commit) {

		error = -ENOMEM;

		goto error_fs_info;
@@ -1588,16 +1550,12 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type, 
		btrfs_sb(s)->bdev_holder = fs_type;

		error = btrfs_fill_super(s, fs_devices, data);

	}

	if (!error)

		error = security_sb_set_mnt_opts(s, &new_sec_opts, 0, NULL);

	security_free_mnt_opts(&new_sec_opts);

	if (error) {

		deactivate_locked_super(s);

		goto error_sec_opts;

	}



	fs_info = btrfs_sb(s);

	error = setup_security_options(fs_info, s, &new_sec_opts);

	if (error) {

		deactivate_locked_super(s);

		goto error_sec_opts;

		return ERR_PTR(error);

	}



	return dget(s->s_root);
@@ -1769,16 +1727,13 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data) 
		struct security_mnt_opts new_sec_opts;



		security_init_mnt_opts(&new_sec_opts);

		ret = parse_security_options(data, &new_sec_opts);

		if (ret)

			goto restore;

		ret = setup_security_options(fs_info, sb,

					     &new_sec_opts);

		if (ret) {

		ret = security_sb_eat_lsm_opts(data, &new_sec_opts);

		if (!ret)

			ret = security_sb_remount(sb, &new_sec_opts);

		security_free_mnt_opts(&new_sec_opts);

		if (ret)

			goto restore;

	}

	}



	ret = btrfs_parse_options(fs_info, data, *flags);

	if (ret)

security/security.c

+1 −0
Original line number Diff line number Diff line
@@ -404,6 +404,7 @@ int security_sb_remount(struct super_block *sb, 
{

	return call_int_hook(sb_remount, 0, sb, opts);

}

EXPORT_SYMBOL(security_sb_remount);



int security_sb_kern_mount(struct super_block *sb)

{

CRA Git | Maintained and supported by SUSTech CRA and CCSE