The patch titled signals: protect cinit from blocked fatal signals has been added to the -mm tree. Its filename is signals-protect-cinit-from-blocked-fatal-signals.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: signals: protect cinit from blocked fatal signals From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx> Normally SIG_DFL signals to global and container-init are dropped early. But if a signal is blocked when it is posted, we cannot drop the signal since the receiver may install a handler before unblocking the signal. Once this signal is queued however, the receiver container-init has no way of knowing if the signal was sent from an ancestor or descendant namespace. This patch ensures that contianer-init drops all SIG_DFL signals in get_signal_to_deliver() except SIGKILL/SIGSTOP. If SIGSTOP/SIGKILL originate from a descendant of container-init they are never queued (i.e dropped in sig_ignored() in an earler patch). If SIGSTOP/SIGKILL originate from parent namespace, the signal is queued and container-init processes the signal. IOW, if get_signal_to_deliver() sees a sig_kernel_only() signal for global or container-init, the signal must have been generated internally or must have come from an ancestor ns and we process the signal. Further, the signal_group_exit() check was needed to cover the case of a multi-threaded init sending SIGKILL to other threads when doing an exit() or exec(). But since the new sig_kernel_only() check covers the SIGKILL, the signal_group_exit() check is no longer needed and can be removed. Finally, now that we have all pieces in place, set SIGNAL_UNKILLABLE for container-inits. Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Roland McGrath <roland@xxxxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Daniel Lezcano <daniel.lezcano@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/fork.c | 2 ++ kernel/signal.c | 9 ++++++++- 2 files changed, 10 insertions(+), 1 deletion(-) diff -puN kernel/fork.c~signals-protect-cinit-from-blocked-fatal-signals kernel/fork.c --- a/kernel/fork.c~signals-protect-cinit-from-blocked-fatal-signals +++ a/kernel/fork.c @@ -844,6 +844,8 @@ static int copy_signal(unsigned long clo atomic_set(&sig->live, 1); init_waitqueue_head(&sig->wait_chldexit); sig->flags = 0; + if (clone_flags & CLONE_NEWPID) + sig->flags |= SIGNAL_UNKILLABLE; sig->group_exit_code = 0; sig->group_exit_task = NULL; sig->group_stop_count = 0; diff -puN kernel/signal.c~signals-protect-cinit-from-blocked-fatal-signals kernel/signal.c --- a/kernel/signal.c~signals-protect-cinit-from-blocked-fatal-signals +++ a/kernel/signal.c @@ -1862,9 +1862,16 @@ relock: /* * Global init gets no signals it doesn't want. + * Container-init gets no signals it doesn't want from same + * container. + * + * Note that if global/container-init sees a sig_kernel_only() + * signal here, the signal must have been generated internally + * or must have come from an ancestor namespace. In either + * case, the signal cannot be dropped. */ if (unlikely(signal->flags & SIGNAL_UNKILLABLE) && - !signal_group_exit(signal)) + !sig_kernel_only(signr)) continue; if (sig_kernel_stop(signr)) { _ Patches currently in -mm which might be from sukadev@xxxxxxxxxxxxxxxxxx are vfs-simple_set_mnt-should-return-void.patch devpts-must-release-s_umount-on-error.patch signals-remove-handler-parameter-to-tracehook-functions.patch signals-protect-init-from-unwanted-signals-more.patch signals-add-from_ancestor_ns-parameter-to-send_signal.patch signals-protect-cinit-from-unblocked-sig_dfl-signals.patch signals-zap_pid_ns_process-should-use-force_sig.patch signals-protect-cinit-from-blocked-fatal-signals.patch signals-si_user-masquerade-si_pid-when-crossing-pid-ns-boundary.patch pids-document-task_pgrp-task_session-is-not-safe-without-tasklist-rcu.patch pids-document-task_pgrp-task_session-is-not-safe-without-tasklist-rcu-fix.patch pids-improve-get_task_pid-to-fix-the-unsafe-sys_wait4-task_pgrp.patch pids-refactor-vnr-nr_ns-helpers-to-make-them-safe.patch pids-kill-now-unused-signal_struct-__pgrp-__session-and-friends.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html