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iproute2: Fail "ip netns add" on existing network namespaces. 

Use O_EXCL so that we only create and mount a new network namespace
if there is no chance an existing network namespace is present.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2011-07-15 14:29:41 +00:00 committed by Stephen Hemminger
parent 2e8a07f543
commit 223f4d8ea6
1 changed files with 5 additions and 12 deletions
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17
ip/ipnetns.c
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@ -41,16 +41,6 @@ static int setns(int fd, int nstype)
#endif /* HAVE_SETNS */ #endif /* HAVE_SETNS */
static int touch(const char *path, mode_t mode)
{
int fd;
fd = open(path, O_RDONLY|O_CREAT, mode);
if (fd < 0)
return -1;
close(fd);
return 0;
}
static void usage(void) __attribute__((noreturn)); static void usage(void) __attribute__((noreturn));
static void usage(void) static void usage(void)
@ -214,6 +204,7 @@ static int netns_add(int argc, char **argv)
*/ */
char netns_path[MAXPATHLEN]; char netns_path[MAXPATHLEN];
const char *name; const char *name;
int fd;
if (argc < 1) { if (argc < 1) {
fprintf(stderr, "No netns name specified\n"); fprintf(stderr, "No netns name specified\n");
@ -227,11 +218,13 @@ static int netns_add(int argc, char **argv)
mkdir(NETNS_RUN_DIR, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH); mkdir(NETNS_RUN_DIR, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
/* Create the filesystem state */ /* Create the filesystem state */
if (touch(netns_path, 0) < 0) { fd = open(netns_path, O_RDONLY|O_CREAT|O_EXCL, 0);
if (fd < 0) {
fprintf(stderr, "Could not create %s: %s\n", fprintf(stderr, "Could not create %s: %s\n",
netns_path, strerror(errno)); netns_path, strerror(errno));
goto out_delete; return -1;
} }
close(fd);
if (unshare(CLONE_NEWNET) < 0) { if (unshare(CLONE_NEWNET) < 0) {
fprintf(stderr, "Failed to create a new network namespace: %s\n", fprintf(stderr, "Failed to create a new network namespace: %s\n",
strerror(errno)); strerror(errno));