From f1e5dfe2c065670e0dac63c7bb2dd82fe820e2ab Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Sun, 22 Apr 2012 00:32:13 +0200 Subject: nspawn: make /dev/kmsg unavailable in the container, but allow access to /proc/kmsg --- src/nspawn/nspawn.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'src/nspawn') diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c index 90c8b94248..71cdd3f39f 100644 --- a/src/nspawn/nspawn.c +++ b/src/nspawn/nspawn.c @@ -394,6 +394,13 @@ static int setup_kmsg(const char *dest, int kmsg_socket) { u = umask(0000); + /* We create the kmsg FIFO as /dev/kmsg, but immediately + * delete it after bind mounting it to /proc/kmsg. While FIFOs + * on the reading side behave very similar to /proc/kmsg, + * their writing side behaves differently from /dev/kmsg in + * that writing blocks when nothing is reading. In order to + * avoid any problems with containers deadlocking due to this + * we simply make /dev/kmsg unavailable to the container. */ if (asprintf(&from, "%s/dev/kmsg", dest) < 0) { log_error("Out of memory"); r = -ENOMEM; @@ -456,6 +463,9 @@ static int setup_kmsg(const char *dest, int kmsg_socket) { goto finish; } + /* And now make the FIFO unavailable as /dev/kmsg... */ + unlink(from); + finish: free(from); free(to); -- cgit v1.2.3-54-g00ecf