diff options
| author | Jann Horn <jannh@google.com> | 2019-03-30 03:12:32 +0100 |
|---|---|---|
| committer | Christian Brauner <christian@brauner.io> | 2019-04-01 23:03:18 +0200 |
| commit | 556a888a14afe27164191955618990fb3ccc9aad (patch) | |
| tree | f9071112a0fe3618bdb437b5b0fa18c6c066719f | |
| parent | 79a3aaa7b82e3106be97842dedfd8429248896e6 (diff) | |
signal: don't silently convert SI_USER signals to non-current pidfd
The current sys_pidfd_send_signal() silently turns signals with explicit
SI_USER context that are sent to non-current tasks into signals with
kernel-generated siginfo.
This is unlike do_rt_sigqueueinfo(), which returns -EPERM in this case.
If a user actually wants to send a signal with kernel-provided siginfo,
they can do that with pidfd_send_signal(pidfd, sig, NULL, 0); so allowing
this case is unnecessary.
Instead of silently replacing the siginfo, just bail out with an error;
this is consistent with other interfaces and avoids special-casing behavior
based on security checks.
Fixes: 3eb39f47934f ("signal: add pidfd_send_signal() syscall")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Christian Brauner <christian@brauner.io>
| -rw-r--r-- | kernel/signal.c | 13 |
1 files changed, 4 insertions, 9 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index b7953934aa99..f98448cf2def 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -3605,16 +3605,11 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, if (unlikely(sig != kinfo.si_signo)) goto err; + /* Only allow sending arbitrary signals to yourself. */ + ret = -EPERM; if ((task_pid(current) != pid) && - (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL)) { - /* Only allow sending arbitrary signals to yourself. */ - ret = -EPERM; - if (kinfo.si_code != SI_USER) - goto err; - - /* Turn this into a regular kill signal. */ - prepare_kill_siginfo(sig, &kinfo); - } + (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL)) + goto err; } else { prepare_kill_siginfo(sig, &kinfo); } |