diff options
| author | Tycho Andersen <tycho@tycho.ws> | 2020-03-04 11:05:17 -0700 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2020-03-04 14:48:54 -0800 |
| commit | 51891498f2da78ee64dfad88fa53c9e85fb50abf (patch) | |
| tree | 6a75fa013734d64980e797831cf123c69cab0c3f /include | |
| parent | 11a48a5a18c63fd7621bb050228cebf13566e4d8 (diff) | |
seccomp: allow TSYNC and USER_NOTIF together
The restriction introduced in 7a0df7fbc145 ("seccomp: Make NEW_LISTENER and
TSYNC flags exclusive") is mostly artificial: there is enough information
in a seccomp user notification to tell which thread triggered a
notification. The reason it was introduced is because TSYNC makes the
syscall return a thread-id on failure, and NEW_LISTENER returns an fd, and
there's no way to distinguish between these two cases (well, I suppose the
caller could check all fds it has, then do the syscall, and if the return
value was an fd that already existed, then it must be a thread id, but
bleh).
Matthew would like to use these two flags together in the Chrome sandbox
which wants to use TSYNC for video drivers and NEW_LISTENER to proxy
syscalls.
So, let's fix this ugliness by adding another flag, TSYNC_ESRCH, which
tells the kernel to just return -ESRCH on a TSYNC error. This way,
NEW_LISTENER (and any subsequent seccomp() commands that want to return
positive values) don't conflict with each other.
Suggested-by: Matthew Denton <mpdenton@google.com>
Signed-off-by: Tycho Andersen <tycho@tycho.ws>
Link: https://lore.kernel.org/r/20200304180517.23867-1-tycho@tycho.ws
Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/seccomp.h | 3 | ||||
| -rw-r--r-- | include/uapi/linux/seccomp.h | 1 |
2 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h index 03583b6d1416..4192369b8418 100644 --- a/include/linux/seccomp.h +++ b/include/linux/seccomp.h @@ -7,7 +7,8 @@ #define SECCOMP_FILTER_FLAG_MASK (SECCOMP_FILTER_FLAG_TSYNC | \ SECCOMP_FILTER_FLAG_LOG | \ SECCOMP_FILTER_FLAG_SPEC_ALLOW | \ - SECCOMP_FILTER_FLAG_NEW_LISTENER) + SECCOMP_FILTER_FLAG_NEW_LISTENER | \ + SECCOMP_FILTER_FLAG_TSYNC_ESRCH) #ifdef CONFIG_SECCOMP diff --git a/include/uapi/linux/seccomp.h b/include/uapi/linux/seccomp.h index be84d87f1f46..c1735455bc53 100644 --- a/include/uapi/linux/seccomp.h +++ b/include/uapi/linux/seccomp.h @@ -22,6 +22,7 @@ #define SECCOMP_FILTER_FLAG_LOG (1UL << 1) #define SECCOMP_FILTER_FLAG_SPEC_ALLOW (1UL << 2) #define SECCOMP_FILTER_FLAG_NEW_LISTENER (1UL << 3) +#define SECCOMP_FILTER_FLAG_TSYNC_ESRCH (1UL << 4) /* * All BPF programs must return a 32-bit value. |