I observe mount command with -o context option fails for btrfs, using mount
command built from the latest util-linux master branch code (git hash
dbf77f7a1).
$ sudo mount -o context="system_u:object_r:root_t:s0" /dev/nullb1 /mnt
mount: /mnt: wrong fs type, bad option, bad superblock on /dev/nullb1, missing codepage or helper program, or other error.
dmesg(1) may have more information after failed mount system call.
Kernel reports an SELinux error message:
[565959.593054][T12131] SELinux: mount invalid. Same superblock, different security settings for (dev nullb1, type btrfs)
Is this a known issue?
Details:
- Mount succeeds without the -o context option.
- Ext4 succeeds to mount with the option.
- Mount succeeds rolling back util-linux code to older git hash 8241fb005,
which was committed on January 3rd. After this commit, a number of commits
were merged to util-linux to use fsconfig syscall for mount in place of
mount syscall.
Then the new fsconfig syscall looks the trigger of the failure. I took a look in
the code of mount path and saw that btrfs is not modified to use struct
fs_context for the fsconfig syscall. The -o context option is parsed and kept in
security field of fs_context, but it is not passed to btrfs_mount.
--
Shin'ichiro Kawasaki
