commit aad82892af ("selinux: Add support for
unprivileged mounts from user namespaces") prohibited any use of context
mount options within non-init user namespaces. However, this breaks
use of context mount options for tmpfs mounts within user namespaces,
which are being used by Docker/runc. There is no reason to block such
usage for tmpfs, ramfs or devpts. Exempt these filesystem types
from this restriction.
Before:
sh$ userns_child_exec -p -m -U -M '0 1000 1' -G '0 1000 1' bash
sh# mount -t tmpfs -o context=system_u:object_r:user_tmp_t:s0:c13 none /tmp
mount: tmpfs is write-protected, mounting read-only
mount: cannot mount tmpfs read-only
After:
sh$ userns_child_exec -p -m -U -M '0 1000 1' -G '0 1000 1' bash
sh# mount -t tmpfs -o context=system_u:object_r:user_tmp_t:s0:c13 none /tmp
sh# ls -Zd /tmp
unconfined_u:object_r:user_tmp_t:s0:c13 /tmp
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
01593d3299