From f333fbb1efc2f32527f78cbdb003d59bae01aa07 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>

Date: Wed, 17 Apr 2013 14:13:09 -0400

Subject: [PATCH] nspawn: create empty /etc/resolv.conf if necessary

nspawn will overmount resolv.conf if it exists. Since e.g.

default install with yum doesn't create /etc/resolv.conf,

a container created with yum will not have network. This

seems undesirable, and since we overmount the file anyway,

let's create it too.

Also, mounting a read-write /etc/resolv.conf in the container

is treated as a failure, since it makes it possible to

modify hosts /etc/resolv.conf from inside the container.

---

 src/nspawn/nspawn.c | 17 ++++++++++++-----

 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c

index f57c75f..5a43d5e 100644

--- a/src/nspawn/nspawn.c

+++ b/src/nspawn/nspawn.c

@@ -492,7 +492,8 @@ static int setup_timezone(const char *dest) {

 }

 static int setup_resolv_conf(const char *dest) {

-        char *where;

+        char _cleanup_free_ *where = NULL;

+        _cleanup_close_ int fd = -1;

         assert(dest);

@@ -504,12 +505,18 @@ static int setup_resolv_conf(const char *dest) {

         if (!where)

                 return log_oom();

+        fd = open(where, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0644);

+

         /* We don't really care for the results of this really. If it

          * fails, it fails, but meh... */

-        if (mount("/etc/resolv.conf", where, "bind", MS_BIND, NULL) >= 0)

-                mount("/etc/resolv.conf", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);

-

-        free(where);

+        if (mount("/etc/resolv.conf", where, "bind", MS_BIND, NULL) < 0)

+                log_warning("Failed to bind mount /etc/resolv.conf: %m");

+        else

+                if (mount("/etc/resolv.conf", where, "bind",

+                          MS_BIND|MS_REMOUNT|MS_RDONLY, NULL) < 0) {

+                        log_error("Failed to remount /etc/resolv.conf readonly: %m");

+                        return -errno;

+                }

         return 0;

 }

-- 

1.8.2