From: Aleksa Sarai cyphar@cyphar.com
commit 398840f8bb935d33c64df4ec4fed77a7d24c267d upstream.
This was an oversight in the original implementation, as it makes no sense to specify both scoping flags to the same openat2(2) invocation (before this patch, the result of such an invocation was equivalent to RESOLVE_IN_ROOT being ignored).
This is a userspace-visible ABI change, but the only user of openat2(2) at the moment is LXC which doesn't specify both flags and so no userspace programs will break as a result.
Fixes: fddb5d430ad9 ("open: introduce openat2(2) syscall") Signed-off-by: Aleksa Sarai cyphar@cyphar.com Acked-by: Christian Brauner christian.brauner@ubuntu.com Cc: stable@vger.kernel.org # v5.6+ Link: https://lore.kernel.org/r/20201027235044.5240-2-cyphar@cyphar.com Signed-off-by: Christian Brauner christian.brauner@ubuntu.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/open.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/fs/open.c +++ b/fs/open.c @@ -1010,6 +1010,10 @@ inline int build_open_flags(const struct if (how->resolve & ~VALID_RESOLVE_FLAGS) return -EINVAL;
+ /* Scoping flags are mutually exclusive. */ + if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT)) + return -EINVAL; + /* Deal with the mode. */ if (WILL_CREATE(flags)) { if (how->mode & ~S_IALLUGO)