When ip creates a netns, there is a small time interval between the
placeholder file creation in NETNS_RUN_DIR and the bind mount from /proc.
Add a temporary file named .mounting-$netns which gets deleted after the
bind mount, so watching for delete event matching the .mounting-* name
will notify watchers only after the bind mount has been done.
Signed-off-by: Matteo Croce <mcr...@redhat.com>
---
ip/ipnetns.c | 37 ++++++++++++++++++++++++++++++-------
1 file changed, 30 insertions(+), 7 deletions(-)
diff --git a/ip/ipnetns.c b/ip/ipnetns.c
index a883f210..23b95173 100644
--- a/ip/ipnetns.c
+++ b/ip/ipnetns.c
@@ -24,6 +24,8 @@
#include "namespace.h"
#include "json_print.h"
+#define TMP_PREFIX ".mounting-"
+
static int usage(void)
{
fprintf(stderr,
@@ -47,6 +49,10 @@ static struct rtnl_handle rtnsh = { .fd = -1 };
static int have_rtnl_getnsid = -1;
static int saved_netns = -1;
+static int is_mounting_stab(const char *name) {
+ return !strncmp(name, TMP_PREFIX, sizeof(TMP_PREFIX) - 1);
+}
+
static int ipnetns_accept_msg(struct rtnl_ctrl_data *ctrl,
struct nlmsghdr *n, void *arg)
{
@@ -379,6 +385,8 @@ static int netns_list(int argc, char **argv)
continue;
if (strcmp(entry->d_name, "..") == 0)
continue;
+ if (is_mounting_stab(entry->d_name))
+ continue;
open_json_object(NULL);
print_string(PRINT_ANY, "name",
@@ -676,7 +684,7 @@ static int netns_add(int argc, char **argv, bool create)
* userspace tweaks like remounting /sys, or bind mounting
* a new /etc/resolv.conf can be shared between users.
*/
- char netns_path[PATH_MAX], proc_path[PATH_MAX];
+ char netns_path[PATH_MAX], tmp_path[PATH_MAX], proc_path[PATH_MAX];
const char *name;
pid_t pid;
int fd;
@@ -701,6 +709,7 @@ static int netns_add(int argc, char **argv, bool create)
name = argv[0];
snprintf(netns_path, sizeof(netns_path), "%s/%s", NETNS_RUN_DIR, name);
+ snprintf(tmp_path, sizeof(tmp_path), "%s/"TMP_PREFIX"%s",
NETNS_RUN_DIR, name);
if (create_netns_dir())
return -1;
@@ -737,6 +746,14 @@ static int netns_add(int argc, char **argv, bool create)
}
close(fd);
+ fd = open(tmp_path, O_RDONLY|O_CREAT|O_EXCL, 0);
+ if (fd < 0) {
+ fprintf(stderr, "Cannot create namespace file \"%s\": %s\n",
+ tmp_path, strerror(errno));
+ goto out_delete;
+ }
+ close(fd);
+
if (create) {
netns_save();
if (unshare(CLONE_NEWNET) < 0) {
@@ -757,6 +774,7 @@ static int netns_add(int argc, char **argv, bool create)
goto out_delete;
}
netns_restore();
+ unlink(tmp_path);
return 0;
out_delete:
@@ -767,6 +785,10 @@ out_delete:
fprintf(stderr, "Cannot remove namespace file \"%s\": %s\n",
netns_path, strerror(errno));
}
+ if (unlink(tmp_path) < 0) {
+ fprintf(stderr, "Cannot remove namespace file \"%s\": %s\n",
+ tmp_path, strerror(errno));
+ }
return -1;
}
@@ -849,7 +871,7 @@ static int netns_monitor(int argc, char **argv)
if (create_netns_dir())
return -1;
- if (inotify_add_watch(fd, NETNS_RUN_DIR, IN_CREATE | IN_DELETE) < 0) {
+ if (inotify_add_watch(fd, NETNS_RUN_DIR, IN_DELETE) < 0) {
fprintf(stderr, "inotify_add_watch failed: %s\n",
strerror(errno));
return -1;
@@ -865,9 +887,9 @@ static int netns_monitor(int argc, char **argv)
for (event = (struct inotify_event *)buf;
(char *)event < &buf[len];
event = (struct inotify_event *)((char *)event +
sizeof(*event) + event->len)) {
- if (event->mask & IN_CREATE)
- printf("add %s\n", event->name);
- if (event->mask & IN_DELETE)
+ if (is_mounting_stab(event->name))
+ printf("add %s\n", event->name +
sizeof(TMP_PREFIX) - 1);
+ else
printf("delete %s\n", event->name);
}
}
@@ -876,8 +898,9 @@ static int netns_monitor(int argc, char **argv)
static int invalid_name(const char *name)
{
- return !*name || strlen(name) > NAME_MAX ||
- strchr(name, '/') || !strcmp(name, ".") || !strcmp(name, "..");
+ return !*name || strlen(name) + sizeof(TMP_PREFIX) - 1 > NAME_MAX ||
+ strchr(name, '/') || !strcmp(name, ".") || !strcmp(name, "..")
||
+ is_mounting_stab(name);
}
int do_netns(int argc, char **argv)
--
2.21.0
