On 12/11/2024 11:56, Sabrina Dubroca wrote:
2024-10-29, 11:47:30 +0100, Antonio Quartulli wrote:
diff --git a/drivers/net/ovpn/io.c b/drivers/net/ovpn/io.c
index 63c140138bf98e5d1df79a2565b666d86513323d..0e8a6f2c76bc7b2ccc287ad1187cf50f033bf261 100644
--- a/drivers/net/ovpn/io.c
+++ b/drivers/net/ovpn/io.c
@@ -135,6 +135,15 @@ void ovpn_decrypt_post(void *data, int ret)
/* keep track of last received authenticated packet for keepalive */
peer->last_recv = ktime_get_real_seconds();
+ if (peer->sock->sock->sk->sk_protocol == IPPROTO_UDP) {
What prevents peer->sock from being replaced and released
concurrently?
Technically nothing.
Userspace currently does not even support updating a peer socket at
runtime, but I wanted ovpn to be flexible enough from the beginning.
One approach might be to go back to peer->sock being unmutable and
forget about this.
OTOH, if we want to keep this flexibility (which I think is nice), I
think I should make peer->sock an RCU pointer and access it accordingly.
Does it make sense?
Or possibly reading the error value that ovpn_socket_new can return
before peer->sock is reset to NULL, just noticed this in
ovpn_nl_peer_modify:
if (attrs[OVPN_A_PEER_SOCKET]) {
// ...
peer->sock = ovpn_socket_new(sock, peer);
if (IS_ERR(peer->sock)) {
// ...
peer->sock = NULL;
(ovpn_encrypt_post has a similar check on
peer->sock->sock->sk->sk_protocol that I don't think is safe either)
Yap, agreed.
+ /* check if this peer changed it's IP address and update
+ * state
+ */
+ ovpn_peer_float(peer, skb);
+ /* update source endpoint for this peer */
+ ovpn_peer_update_local_endpoint(peer, skb);
Why not do both in the same function? They're not called anywhere else
(at least in this version of the series). They both modify peer->bind
depending on skb_protocol_to_family(skb), and operate under
peer->lock.
I never considered to do so as I just always assumed the two to be two
separate features/routines.
I think it's a good idea and I would get rid of a few common
instructions (along with acquiring the lock twice). Thanks!
+void ovpn_peer_float(struct ovpn_peer *peer, struct sk_buff *skb)
+{
+ struct hlist_nulls_head *nhead;
+ struct sockaddr_storage ss;
+ const u8 *local_ip = NULL;
+ struct sockaddr_in6 *sa6;
+ struct sockaddr_in *sa;
+ struct ovpn_bind *bind;
+ sa_family_t family;
+ size_t salen;
+
+ rcu_read_lock();
+ bind = rcu_dereference(peer->bind);
+ if (unlikely(!bind)) {
+ rcu_read_unlock();
+ return;
+ }
+
+ spin_lock_bh(&peer->lock);
You could take the lock from the start, instead of using rcu_read_lock
to get peer->bind. It would guarantee that the bind we got isn't
already being replaced just as we wait to update it. And same in
ovpn_peer_update_local_endpoint, it would make sure we're updating the
local IP for the active bind.
(sorry I didn't think about that last time we discussed this)
no worries :) and I like the idea. will do that, thanks.
+ if (likely(ovpn_bind_skb_src_match(bind, skb)))
+ goto unlock;
+
+ family = skb_protocol_to_family(skb);
+
--
Antonio Quartulli
OpenVPN Inc.
