iproute2: Make "ip netns delete" more likely to succeed
Sometimes "ip netns delete" fails because it can not delete the file a
network namespace was mounted on. If this only happened when a
network namespace was really in use this would be fine, but today it
is possible to pin all network namespaces by simply having a long
running process started with "ip netns exec".
Every mount is copied when a network namespace is created so it is
impossible to prevent the mounts from getting into other mount
namespaces. Modify all mounts in the files and subdirectories of
/var/run/netns to be shared mount points so that unmount events can
propogate, making it unlikely that "ip netns delete" will fail because
a directory is mounted in another mount namespace.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/ip/ipnetns.c b/ip/ipnetns.c
index 4fce379..33765b5 100644
--- a/ip/ipnetns.c
+++ b/ip/ipnetns.c
@@ -208,6 +208,7 @@
char netns_path[MAXPATHLEN];
const char *name;
int fd;
+ int made_netns_run_dir_mount = 0;
if (argc < 1) {
fprintf(stderr, "No netns name specified\n");
@@ -220,6 +221,29 @@
/* Create the base netns directory if it doesn't exist */
mkdir(NETNS_RUN_DIR, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
+ /* Make it possible for network namespace mounts to propogate between
+ * mount namespaces. This makes it likely that a unmounting a network
+ * namespace file in one namespace will unmount the network namespace
+ * file in all namespaces allowing the network namespace to be freed
+ * sooner.
+ */
+ while (mount("", NETNS_RUN_DIR, "none", MS_SHARED | MS_REC, NULL)) {
+ /* Fail unless we need to make the mount point */
+ if (errno != EINVAL || made_netns_run_dir_mount) {
+ fprintf(stderr, "mount --make-shared %s failed: %s\n",
+ NETNS_RUN_DIR, strerror(errno));
+ return EXIT_FAILURE;
+ }
+
+ /* Upgrade NETNS_RUN_DIR to a mount point */
+ if (mount(NETNS_RUN_DIR, NETNS_RUN_DIR, "none", MS_BIND, NULL)) {
+ fprintf(stderr, "mount --bind %s %s failed: %s\n",
+ NETNS_RUN_DIR, NETNS_RUN_DIR, strerror(errno));
+ return EXIT_FAILURE;
+ }
+ made_netns_run_dir_mount = 1;
+ }
+
/* Create the filesystem state */
fd = open(netns_path, O_RDONLY|O_CREAT|O_EXCL, 0);
if (fd < 0) {
