On 9/7/22 19:28, Eric Dumazet wrote:
On Wed, Sep 7, 2022 at 9:19 AM Leonard Crestez cdleonard@gmail.com wrote:
On 9/7/22 01:57, Eric Dumazet wrote:
On Mon, Sep 5, 2022 at 12:06 AM Leonard Crestez cdleonard@gmail.com wrote:
This commit adds support to add and remove keys but does not use them further.
Similar to tcp md5 a single pointer to a struct tcp_authopt_info* struct is added to struct tcp_sock, this avoids increasing memory usage. The data structures related to tcp_authopt are initialized on setsockopt and only freed on socket close.
Thanks Leonard.
Small points from my side, please find them attached.
...
+/* Free info and keys.
- Don't touch tp->authopt_info, it might not even be assigned yes.
- */
+void tcp_authopt_free(struct sock *sk, struct tcp_authopt_info *info) +{
kfree_rcu(info, rcu);+}
+/* Free everything and clear tcp_sock.authopt_info to NULL */ +void tcp_authopt_clear(struct sock *sk) +{
struct tcp_authopt_info *info;info = rcu_dereference_protected(tcp_sk(sk)->authopt_info, lockdep_sock_is_held(sk));if (info) {tcp_authopt_free(sk, info);tcp_sk(sk)->authopt_info = NULL;RCU rules at deletion mandate that the pointer must be cleared before the call_rcu()/kfree_rcu() call.
It is possible that current MD5 code has an issue here, let's not copy/paste it.
OK. Is there a need for some special form of assignment or is current plain form enough?
It is the right way (when clearing the pointer), no need for another form.
OK
+/* checks that ipv4 or ipv6 addr matches. */ +static bool ipvx_addr_match(struct sockaddr_storage *a1,
struct sockaddr_storage *a2)+{
if (a1->ss_family != a2->ss_family)return false;if (a1->ss_family == AF_INET &&(((struct sockaddr_in *)a1)->sin_addr.s_addr !=((struct sockaddr_in *)a2)->sin_addr.s_addr))return false;if (a1->ss_family == AF_INET6 &&!ipv6_addr_equal(&((struct sockaddr_in6 *)a1)->sin6_addr,&((struct sockaddr_in6 *)a2)->sin6_addr))return false;return true;+}
Always surprising to see this kind of generic helper being added in a patch.
I remember looking for an equivalent and not finding it. Many places have distinct code paths for ipv4 and ipv6 and my use of "sockaddr_storage" as ipv4/ipv6 union is uncommon.
inetpeer_addr_cmp() might do it (and we also could fix a bug in it it seems, at least for __tcp_get_metrics() usage :/
That uses a different `struct inetpeer_addr` which also has some extra "vif" fields for ipv4 that I don't know about.
Everybody seems to be rolling their own ipv4/v6 union, other examples are `struct tcp_md5_addr` and `xfrm_address_t`. struct sockaddr_storage is "more standard" but also larger so maybe that's why others don't use it.
+int tcp_get_authopt_val(struct sock *sk, struct tcp_authopt *opt) +{
struct tcp_sock *tp = tcp_sk(sk);struct tcp_authopt_info *info;memset(opt, 0, sizeof(*opt));sock_owned_by_me(sk);info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk));Probably not a big deal, but it seems the prior sock_owned_by_me() might be redundant.
The sock_owned_by_me call checks checks lockdep_sock_is_held
The rcu_dereference_check call checks lockdep_sock_is_held || rcu_read_lock_held()
Then if you own the socket lock, no need for rcu_dereference_check()
It could be instead an rcu_dereference_protected(). This is stronger, because if your thread no longer owns the socket lock, but is inside rcu_read_lock(), we would still get a proper lockdep splat.
Ok, I think there are several places where rcu_dereference_check is incorrectly used instead of rcu_dereference_protected.