pasta: Improve error handling on failure to join network namespace

In pasta_wait_for_ns(), open() failing with ENOENT is expected: we're
busy-looping until the network namespace appears. But any other
failure is not something we're going to recover from: return right
away if we don't get either success or ENOENT.

Now that pasta_wait_for_ns() can actually fail, handle that in
pasta_start_ns() by reporting the issue and exiting.

Looping on EPERM, when pasta doesn't actually have the permissions to
join a given namespace, isn't exactly a productive thing to do.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2023-05-14 13:32:41 +02:00
parent 1c3c68970e
commit f099afb1f2

13
pasta.c
View file

@ -95,10 +95,13 @@ static int pasta_wait_for_ns(void *arg)
char ns[PATH_MAX];
snprintf(ns, PATH_MAX, "/proc/%i/ns/net", pasta_child_pid);
do
while ((c->pasta_netns_fd = open(ns, flags)) < 0);
while (setns(c->pasta_netns_fd, CLONE_NEWNET) &&
!close(c->pasta_netns_fd));
do {
while ((c->pasta_netns_fd = open(ns, flags)) < 0) {
if (errno != ENOENT)
return 0;
}
} while (setns(c->pasta_netns_fd, CLONE_NEWNET) &&
!close(c->pasta_netns_fd));
return 0;
}
@ -257,6 +260,8 @@ void pasta_start_ns(struct ctx *c, uid_t uid, gid_t gid,
}
NS_CALL(pasta_wait_for_ns, c);
if (c->pasta_netns_fd < 0)
die("Failed to join network namespace");
}
/**