[PATCH AUTOSEL 5.18 10/93] bpf, sockmap: Fix sk->sk_forward_alloc warn_on in sk_stream_kill_queues

Sasha Levin
2022-08-11T15:52:24Z

From: Wang Yufen <wangyufen@huawei.com>

[ Upstream commit d8616ee2affcff37c5d315310da557a694a3303d ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/bpf.h | 1 +
include/linux/skmsg.h | 1 +
net/core/skmsg.c | 1 +
net/core/sock_map.c | 23 +++++++++++++++++++++++
net/ipv4/tcp_bpf.c | 1 +
5 files changed, 27 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 83bd5598ec4d..5db26f20aa70 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2012,6 +2012,7 @@ 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 c5a2d6f50f25..153b6dec9b6a 100644
--- 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 ede0af308f40..2742d8e4dd82 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -716,6 +716,7 @@ 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 2d213c4011db..9947c1f94dc3 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -1563,6 +1563,29 @@ 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 2c597a4e429a..25e83d35138b 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -541,6 +541,7 @@ 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;
--
2.35.1