[PATCH bpf v9 3/5] bpf: disable non stream socket for strparser

Jiayuan Chen
2025-01-22T10:11:57Z

Currently, only TCP supports strparser, but sockmap doesn't intercept
non-TCP connections to attach strparser. For example, with UDP, although
the read/write handlers are replaced, strparser is not executed due to
the lack of a read_sock operation.

Furthermore, in udp_bpf_recvmsg(), it checks whether the psock has data,
and if not, it falls back to the native UDP read interface, making
UDP + strparser appear to read correctly. According to its commit history,
this behavior is unexpected.

Moreover, since UDP lacks the concept of streams, we intercept it directly.

Fixes: 1fa1fe8ff161 ("bpf, sockmap: Test shutdown() correctly exits epoll and recv()=0")
Signed-off-by: Jiayuan Chen <mrpre@163.com>
---
net/core/sock_map.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index f1b9b3958792..3b0f59d9b4db 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -303,7 +303,10 @@ static int sock_map_link(struct bpf_map *map, struct sock *sk)

write_lock_bh(&sk->sk_callback_lock);
if (stream_parser && stream_verdict && !psock->saved_data_ready) {
- ret = sk_psock_init_strp(sk, psock);
+ if (sk_is_tcp(sk))
+ ret = sk_psock_init_strp(sk, psock);
+ else
+ ret = -EOPNOTSUPP;
if (ret) {
write_unlock_bh(&sk->sk_callback_lock);
sk_psock_put(sk, psock);
--
2.43.5