From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Fastabend Subject: [bpf PATCH 2/4] bpf: sockhash, disallow bpf_tcp_close and update in parallel Date: Thu, 05 Jul 2018 08:36:21 -0700 Message-ID: <20180705153621.15312.32958.stgit@john-Precision-Tower-5810> References: <20180705152803.15312.47795.stgit@john-Precision-Tower-5810> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, john.fastabend@gmail.com To: ast@kernel.org, daniel@iogearbox.net Return-path: Received: from [184.63.162.180] ([184.63.162.180]:39568 "EHLO john-Precision-Tower-5810" rhost-flags-FAIL-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753466AbeGEPg0 (ORCPT ); Thu, 5 Jul 2018 11:36:26 -0400 In-Reply-To: <20180705152803.15312.47795.stgit@john-Precision-Tower-5810> Sender: netdev-owner@vger.kernel.org List-ID: After latest lock updates there is no longer anything preventing a close and recvmsg call running in parallel. Additionally, we can race update with close if we close a socket and simultaneously update if via the BPF userspace API (note the cgroup ops are already run with sock_lock held). To resolve this take sock_lock in close and update paths. Reported-by: syzbot+b680e42077a0d7c9a0c4@syzkaller.appspotmail.com Fixes: e9db4ef6bf4c ("bpf: sockhash fix omitted bucket lock in sock_close") Signed-off-by: John Fastabend --- 0 files changed diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c index 00fb2e3..9c67e96 100644 --- a/kernel/bpf/sockmap.c +++ b/kernel/bpf/sockmap.c @@ -312,10 +312,12 @@ static void bpf_tcp_close(struct sock *sk, long timeout) struct smap_psock *psock; struct sock *osk; + lock_sock(sk); rcu_read_lock(); psock = smap_psock_sk(sk); if (unlikely(!psock)) { rcu_read_unlock(); + release_sock(sk); return sk->sk_prot->close(sk, timeout); } @@ -371,6 +373,7 @@ static void bpf_tcp_close(struct sock *sk, long timeout) e = psock_map_pop(sk, psock); } rcu_read_unlock(); + release_sock(sk); close_fun(sk, timeout); } @@ -2069,7 +2072,13 @@ static int sock_map_update_elem(struct bpf_map *map, return -EOPNOTSUPP; } + lock_sock(skops.sk); + preempt_disable(); + rcu_read_lock(); err = sock_map_ctx_update_elem(&skops, map, key, flags); + rcu_read_unlock(); + preempt_enable(); + release_sock(skops.sk); fput(socket->file); return err; } @@ -2410,7 +2419,13 @@ static int sock_hash_update_elem(struct bpf_map *map, return -EINVAL; } + lock_sock(skops.sk); + preempt_disable(); + rcu_read_lock(); err = sock_hash_ctx_update_elem(&skops, map, key, flags); + rcu_read_unlock(); + preempt_enable(); + release_sock(skops.sk); fput(socket->file); return err; } diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index d10ecd7..a31a1ba 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -735,7 +735,9 @@ static int map_update_elem(union bpf_attr *attr) if (bpf_map_is_dev_bound(map)) { err = bpf_map_offload_update_elem(map, key, value, attr->flags); goto out; - } else if (map->map_type == BPF_MAP_TYPE_CPUMAP) { + } else if (map->map_type == BPF_MAP_TYPE_CPUMAP || + map->map_type == BPF_MAP_TYPE_SOCKHASH || + map->map_type == BPF_MAP_TYPE_SOCKMAP) { err = map->ops->map_update_elem(map, key, value, attr->flags); goto out; }