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authorOleg Nesterov <oleg@redhat.com>2012-12-17 16:03:07 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-17 17:15:22 -0800
commit992fb6e170639b0849bace8e49bf31bd37c4123c (patch)
tree29f54e489ea095aba284fd4b1feb7201347eb70c /kernel/ptrace.c
parent462e471107624fe9bd8b6353ac13e06305c3f3fd (diff)
downloadlwn-992fb6e170639b0849bace8e49bf31bd37c4123c.tar.gz
lwn-992fb6e170639b0849bace8e49bf31bd37c4123c.zip
ptrace: introduce PTRACE_O_EXITKILL
Ptrace jailers want to be sure that the tracee can never escape from the control. However if the tracer dies unexpectedly the tracee continues to run in potentially unsafe mode. Add the new ptrace option PTRACE_O_EXITKILL. If the tracer exits it sends SIGKILL to every tracee which has this bit set. Note that the new option is not equal to the last-option << 1. Because currently all options have an event, and the new one starts the eventless group. It uses the random 20 bit, so we have the room for 12 more events, but we can also add the new eventless options below this one. Suggested by Amnon Shiloh. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Tested-by: Amnon Shiloh <u3557@miso.sublimeip.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Serge Hallyn <serge.hallyn@canonical.com> Cc: Chris Evans <scarybeasts@gmail.com> Cc: David Howells <dhowells@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/ptrace.c')
-rw-r--r--kernel/ptrace.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 1f5e55dda955..ec8118ab2a47 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -457,6 +457,9 @@ void exit_ptrace(struct task_struct *tracer)
return;
list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
+ if (unlikely(p->ptrace & PT_EXITKILL))
+ send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
+
if (__ptrace_detach(tracer, p))
list_add(&p->ptrace_entry, &ptrace_dead);
}