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: 3eb39f4793
("signal: add pidfd_send_signal() syscall")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Christian Brauner <christian@brauner.io>
This commit is contained in:
Родитель
79a3aaa7b8
Коммит
556a888a14
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@ -3605,16 +3605,11 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
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if (unlikely(sig != kinfo.si_signo))
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goto err;
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/* Only allow sending arbitrary signals to yourself. */
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ret = -EPERM;
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if ((task_pid(current) != pid) &&
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(kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL)) {
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/* Only allow sending arbitrary signals to yourself. */
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ret = -EPERM;
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if (kinfo.si_code != SI_USER)
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goto err;
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/* Turn this into a regular kill signal. */
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prepare_kill_siginfo(sig, &kinfo);
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}
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(kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
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goto err;
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} else {
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prepare_kill_siginfo(sig, &kinfo);
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}
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