diff mbox series

[2/8] libbtrfsutil: don't check for UID 0 in subvolume_info()

Message ID 0455327c82f908ef22491b40957d4f4bbd30bc60.1718995160.git.osandov@fb.com (mailing list archive)
State New, archived
Headers show
Series btrfs-progs: add subvol list options for sane path behavior | expand

Commit Message

Omar Sandoval June 21, 2024, 6:53 p.m. UTC 
From: Omar Sandoval <osandov@fb.com>

btrfs_util_subvolume_info() explicitly checks whether geteuid() == 0 to
decide whether to use the unprivileged BTRFS_IOC_GET_SUBVOL_INFO ioctl
or the privileged BTRFS_IOC_TREE_SEARCH ioctl. This breaks in user
namespaces:

  $ unshare -r python3 -c 'import btrfsutil; print(btrfsutil.subvolume_info("/"))'
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
  btrfsutil.BtrfsUtilError: [BtrfsUtilError 12 Errno 1] Could not search B-tree: Operation not permitted: '/'

The unprivileged ioctl has been supported since Linux 4.18. Let's try
the unprivileged ioctl first, then fall back to the privileged version
only if it isn't supported.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 libbtrfsutil/subvolume.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/libbtrfsutil/subvolume.c b/libbtrfsutil/subvolume.c
index 1f0f2d2b..70f2ec70 100644
--- a/libbtrfsutil/subvolume.c
+++ b/libbtrfsutil/subvolume.c
@@ -451,8 +451,10 @@  PUBLIC enum btrfs_util_error btrfs_util_subvolume_info_fd(int fd, uint64_t id,
 		if (err)
 			return err;
 
-		if (!is_root())
-			return get_subvolume_info_unprivileged(fd, subvol);
+		err = get_subvolume_info_unprivileged(fd, subvol);
+		if (err != BTRFS_UTIL_ERROR_GET_SUBVOL_INFO_FAILED ||
+		    errno != ENOTTY)
+			return err;
 
 		err = btrfs_util_subvolume_id_fd(fd, &id);
 		if (err)