The patch titled
signals: protect cinit from unblocked SIG_DFL signals
has been added to the -mm tree. Its filename is
signals-protect-cinit-from-unblocked-sig_dfl-signals.patch
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*** 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 unblocked SIG_DFL signals
From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
Drop early any SIG_DFL or SIG_IGN signals to container-init from within
the same container. But queue SIGSTOP and SIGKILL to the container-init
if they are from an ancestor container.
Blocked, fatal signals (i.e when SIG_DFL is to terminate) from within the
container can still terminate the container-init. That will be addressed
in the next patch.
Note: To be bisect-safe, SIGNAL_UNKILLABLE will be set for container-inits
in a follow-on patch. Until then, this patch is just a preparatory
step.
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/signal.c | 28 +++++++++++++++++++---------
1 file changed, 19 insertions(+), 9 deletions(-)
diff -puN kernel/signal.c~signals-protect-cinit-from-unblocked-sig_dfl-signals kernel/signal.c
--- a/kernel/signal.c~signals-protect-cinit-from-unblocked-sig_dfl-signals
+++ a/kernel/signal.c
@@ -55,20 +55,21 @@ static int sig_handler_ignored(void __us
(handler == SIG_DFL && sig_kernel_ignore(sig));
}
-static int sig_task_ignored(struct task_struct *t, int sig)
+static int sig_task_ignored(struct task_struct *t, int sig,
+ int from_ancestor_ns)
{
void __user *handler;
handler = sig_handler(t, sig);
if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
- handler == SIG_DFL)
+ handler == SIG_DFL && !from_ancestor_ns)
return 1;
return sig_handler_ignored(handler, sig);
}
-static int sig_ignored(struct task_struct *t, int sig)
+static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
{
/*
* Blocked signals are never ignored, since the
@@ -78,7 +79,7 @@ static int sig_ignored(struct task_struc
if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
return 0;
- if (!sig_task_ignored(t, sig))
+ if (!sig_task_ignored(t, sig, from_ancestor_ns))
return 0;
/*
@@ -634,7 +635,7 @@ static int check_kill_permission(int sig
* Returns true if the signal should be actually delivered, otherwise
* it should be dropped.
*/
-static int prepare_signal(int sig, struct task_struct *p)
+static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
{
struct signal_struct *signal = p->signal;
struct task_struct *t;
@@ -718,7 +719,7 @@ static int prepare_signal(int sig, struc
}
}
- return !sig_ignored(p, sig);
+ return !sig_ignored(p, sig, from_ancestor_ns);
}
/*
@@ -832,7 +833,8 @@ static int __send_signal(int sig, struct
trace_sched_signal_send(sig, t);
assert_spin_locked(&t->sighand->siglock);
- if (!prepare_signal(sig, t))
+
+ if (!prepare_signal(sig, t, from_ancestor_ns))
return 0;
pending = group ? &t->signal->shared_pending : &t->pending;
@@ -902,7 +904,15 @@ out_set:
static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
int group)
{
- return __send_signal(sig, info, t, group, 0);
+ int from_ancestor_ns = 0;
+
+#ifdef CONFIG_PID_NS
+ if (!is_si_special(info) && SI_FROMUSER(info) &&
+ task_pid_nr_ns(current, task_active_pid_ns(t)) <= 0)
+ from_ancestor_ns = 1;
+#endif
+
+ return __send_signal(sig, info, t, group, from_ancestor_ns);
}
int print_fatal_signals;
@@ -1336,7 +1346,7 @@ int send_sigqueue(struct sigqueue *q, st
goto ret;
ret = 1; /* the signal is ignored */
- if (!prepare_signal(sig, t))
+ if (!prepare_signal(sig, t, 0))
goto out;
ret = 0;
_
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
--
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