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=== Description (from pull-request) ===
The problem here is that these two clauses were ordered backwards: we first
check if the signal came from not the init pid, and if it did, then we give
a notice and return. The comment notes that this is intended to protect
against SIGCHLD, but we don't in fact know if the signal is a SIGCHLD yet,
because that's tested in the next hunk.
The symptom is that if I e.g. send SIGTERM from the outside world to the
container init, it ignores it and gives this notice. If we re-order these
clauses, it forwards non SIGCHLD signals, and ignores SIGCHLD signals from
things that aren't the real container process.
Signed-off-by: Tycho Andersen <ty...@tycho.ws>
From 9cb943843a70cef5478d224615ca53c315020ef3 Mon Sep 17 00:00:00 2001
From: Tycho Andersen <ty...@tycho.ws>
Date: Wed, 4 Apr 2018 17:45:29 -0600
Subject: [PATCH] fix signal sending in lxc.init
The problem here is that these two clauses were ordered backwards: we first
check if the signal came from not the init pid, and if it did, then we give
a notice and return. The comment notes that this is intended to protect
against SIGCHLD, but we don't in fact know if the signal is a SIGCHLD yet,
because that's tested in the next hunk.
The symptom is that if I e.g. send SIGTERM from the outside world to the
container init, it ignores it and gives this notice. If we re-order these
clauses, it forwards non SIGCHLD signals, and ignores SIGCHLD signals from
things that aren't the real container process.
Signed-off-by: Tycho Andersen <ty...@tycho.ws>
---
src/lxc/start.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/src/lxc/start.c b/src/lxc/start.c
index f66f50a7b..d7f079979 100644
--- a/src/lxc/start.c
+++ b/src/lxc/start.c
@@ -380,6 +380,12 @@ static int signal_handler(int fd, uint32_t events, void
*data,
return hdlr->init_died ? LXC_MAINLOOP_CLOSE : 0;
}
+ if (siginfo.ssi_signo != SIGCHLD) {
+ kill(hdlr->pid, siginfo.ssi_signo);
+ INFO("Forwarded signal %d to pid %d", siginfo.ssi_signo,
hdlr->pid);
+ return hdlr->init_died ? LXC_MAINLOOP_CLOSE : 0;
+ }
+
/* More robustness, protect ourself from a SIGCHLD sent
* by a process different from the container init.
*/
@@ -389,12 +395,6 @@ static int signal_handler(int fd, uint32_t events, void
*data,
return hdlr->init_died ? LXC_MAINLOOP_CLOSE : 0;
}
- if (siginfo.ssi_signo != SIGCHLD) {
- kill(hdlr->pid, siginfo.ssi_signo);
- INFO("Forwarded signal %d to pid %d", siginfo.ssi_signo,
hdlr->pid);
- return hdlr->init_died ? LXC_MAINLOOP_CLOSE : 0;
- }
-
if (siginfo.ssi_code == CLD_STOPPED) {
INFO("Container init process was stopped");
return hdlr->init_died ? LXC_MAINLOOP_CLOSE : 0;
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