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authorOleg Nesterov <oleg@redhat.com>2012-12-17 19:03:07 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-17 20:15:22 -0500
commit992fb6e170639b0849bace8e49bf31bd37c4123c (patch)
tree29f54e489ea095aba284fd4b1feb7201347eb70c /kernel
parent462e471107624fe9bd8b6353ac13e06305c3f3fd (diff)
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')
-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)
457 return; 457 return;
458 458
459 list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) { 459 list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
460 if (unlikely(p->ptrace & PT_EXITKILL))
461 send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
462
460 if (__ptrace_detach(tracer, p)) 463 if (__ptrace_detach(tracer, p))
461 list_add(&p->ptrace_entry, &ptrace_dead); 464 list_add(&p->ptrace_entry, &ptrace_dead);
462 } 465 }