bpf, sockmap: Fix sk->sk_forward_alloc warn_on in sk_stream_kill_queues

During TCP sockmap redirect pressure test, the following warning is triggered:

WARNING: CPU: 3 PID: 2145 at net/core/stream.c:205 sk_stream_kill_queues+0xbc/0xd0
CPU: 3 PID: 2145 Comm: iperf Kdump: loaded Tainted: G        W         5.10.0+ #9
Call Trace:
 inet_csk_destroy_sock+0x55/0x110
 inet_csk_listen_stop+0xbb/0x380
 tcp_close+0x41b/0x480
 inet_release+0x42/0x80
 __sock_release+0x3d/0xa0
 sock_close+0x11/0x20
 __fput+0x9d/0x240
 task_work_run+0x62/0x90
 exit_to_user_mode_prepare+0x110/0x120
 syscall_exit_to_user_mode+0x27/0x190
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The reason we observed is that:

When the listener is closing, a connection may have completed the three-way
handshake but not accepted, and the client has sent some packets. The child
sks in accept queue release by inet_child_forget()->inet_csk_destroy_sock(),
but psocks of child sks have not released.

To fix, add sock_map_destroy to release psocks.

Signed-off-by: Wang Yufen <wangyufen@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20220524075311.649153-1-wangyufen@huawei.com

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 2b914a56a2c538405e5bb77cecf22cd33e393adb..8e6092d0ea9566d04ff221f0924d0b05841abbcd 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2104,6 +2104,7 @@ int sock_map_bpf_prog_query(const union bpf_attr *attr,
                            union bpf_attr __user *uattr);
 
 void sock_map_unhash(struct sock *sk);
+void sock_map_destroy(struct sock *sk);
 void sock_map_close(struct sock *sk, long timeout);
 #else
 static inline int bpf_prog_offload_init(struct bpf_prog *prog,

diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
index c5a2d6f50f25bb845faef6fcb61492b39d926c80..153b6dec9b6ae1da1bd98bf1f2bdbc21629c58df 100644 (file)
--- a/include/linux/skmsg.h
+++ b/include/linux/skmsg.h
@@ -95,6 +95,7 @@ struct sk_psock {
        spinlock_t                      link_lock;
        refcount_t                      refcnt;
        void (*saved_unhash)(struct sock *sk);
+       void (*saved_destroy)(struct sock *sk);
        void (*saved_close)(struct sock *sk, long timeout);
        void (*saved_write_space)(struct sock *sk);
        void (*saved_data_ready)(struct sock *sk);

diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index 22b983ade0e7da7fcbf54e91b326b61bb23b1532..7e03f96e441b2271b9b9a0907708933c5d805b55 100644 (file)
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -715,6 +715,7 @@ struct sk_psock *sk_psock_init(struct sock *sk, int node)
        psock->eval = __SK_NONE;
        psock->sk_proto = prot;
        psock->saved_unhash = prot->unhash;
+       psock->saved_destroy = prot->destroy;
        psock->saved_close = prot->close;
        psock->saved_write_space = sk->sk_write_space;
 

diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 81d4b4756a02d4e47cb8d5db39fb16a1cccc1e72..9f08ccfaf6da8bca0b9847b0d42be980bd43af19 100644 (file)
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -1561,6 +1561,29 @@ void sock_map_unhash(struct sock *sk)
 }
 EXPORT_SYMBOL_GPL(sock_map_unhash);
 
+void sock_map_destroy(struct sock *sk)
+{
+       void (*saved_destroy)(struct sock *sk);
+       struct sk_psock *psock;
+
+       rcu_read_lock();
+       psock = sk_psock_get(sk);
+       if (unlikely(!psock)) {
+               rcu_read_unlock();
+               if (sk->sk_prot->destroy)
+                       sk->sk_prot->destroy(sk);
+               return;
+       }
+
+       saved_destroy = psock->saved_destroy;
+       sock_map_remove_links(sk, psock);
+       rcu_read_unlock();
+       sk_psock_stop(psock, true);
+       sk_psock_put(sk, psock);
+       saved_destroy(sk);
+}
+EXPORT_SYMBOL_GPL(sock_map_destroy);
+
 void sock_map_close(struct sock *sk, long timeout)
 {
        void (*saved_close)(struct sock *sk, long timeout);

diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index be3947e70fec57cee1342bbf4e77ffc32cad4f9c..38550bb1b90baf1bc3940e6889dac498c43c69b9 100644 (file)
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -540,6 +540,7 @@ static void tcp_bpf_rebuild_protos(struct proto prot[TCP_BPF_NUM_CFGS],
                                   struct proto *base)
 {
        prot[TCP_BPF_BASE]                      = *base;
+       prot[TCP_BPF_BASE].destroy              = sock_map_destroy;
        prot[TCP_BPF_BASE].close                = sock_map_close;
        prot[TCP_BPF_BASE].recvmsg              = tcp_bpf_recvmsg;
        prot[TCP_BPF_BASE].sock_is_readable     = sk_msg_is_readable;