Messages in this thread Patch in this message | | | Date | Wed, 7 Sep 2022 19:19:00 +0300 | Subject | Re: [PATCH v8 01/26] tcp: authopt: Initial support and key management | From | Leonard Crestez <> |
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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?
> >> + } >> +} >> + >> +/* 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.
It also wastes some memory.
>> +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()
This is a getsockopt so caller ensures socket locking but rcu_read_lock_held() == 0.
The sock_owned_by_me is indeed redundant because it seems very unlikely the sockopt calling conditions will be changes. It was mostly there to clarify for myself because I had probably at one time with locking warnings. I guess they can be removed.
>> +int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen) >> +{ >> + struct tcp_authopt_key opt; >> + struct tcp_authopt_info *info; >> + struct tcp_authopt_key_info *key_info, *old_key_info; >> + struct netns_tcp_authopt *net = sock_net_tcp_authopt(sk); >> + int err; >> + >> + sock_owned_by_me(sk); >> + if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) >> + return -EPERM; >> + >> + err = _copy_from_sockptr_tolerant((u8 *)&opt, sizeof(opt), optval, optlen); >> + if (err) >> + return err; >> + >> + if (opt.flags & ~TCP_AUTHOPT_KEY_KNOWN_FLAGS) >> + return -EINVAL; >> + >> + if (opt.keylen > TCP_AUTHOPT_MAXKEYLEN) >> + return -EINVAL; >> + >> + /* Delete is a special case: */ >> + if (opt.flags & TCP_AUTHOPT_KEY_DEL) { >> + mutex_lock(&net->mutex); >> + key_info = tcp_authopt_key_lookup_exact(sk, net, &opt); >> + if (key_info) { >> + tcp_authopt_key_del(net, key_info); >> + err = 0; >> + } else { >> + err = -ENOENT; >> + } >> + mutex_unlock(&net->mutex); >> + return err; >> + } >> + >> + /* check key family */ >> + if (opt.flags & TCP_AUTHOPT_KEY_ADDR_BIND) { >> + if (sk->sk_family != opt.addr.ss_family) >> + return -EINVAL; >> + } >> + >> + /* Initialize tcp_authopt_info if not already set */ >> + info = __tcp_authopt_info_get_or_create(sk); >> + if (IS_ERR(info)) >> + return PTR_ERR(info); >> + >> + key_info = kmalloc(sizeof(*key_info), GFP_KERNEL | __GFP_ZERO); > > kzalloc() ?
Yes
>> +static int tcp_authopt_init_net(struct net *full_net) > > Hmmm... our convention is to use "struct net *net" > >> +{ >> + struct netns_tcp_authopt *net = &full_net->tcp_authopt; > > Here, you should use a different name ...
OK, will replace with net_ao
>> @@ -2267,10 +2268,11 @@ void tcp_v4_destroy_sock(struct sock *sk) >> tcp_clear_md5_list(sk); >> kfree_rcu(rcu_dereference_protected(tp->md5sig_info, 1), rcu); >> tp->md5sig_info = NULL; >> } >> #endif >> + tcp_authopt_clear(sk); > > Do we really own the socket lock at this point ?
Not sure how I would tell but there is a lockdep_sock_is_held check inside tcp_authopt_clear. I also added sock_owned_by_me and there were no warnings.
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