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[bpf,v8,3/5] bpf: disable non stream socket for strparser

Message ID 20250121050707.55523-4-mrpre@163.com (mailing list archive)
State New
Headers show
Series bpf: fix wrong copied_seq calculation and add tests | expand

Commit Message

Jiayuan Chen Jan. 21, 2025, 5:07 a.m. UTC
Currently, only TCP supports strparser, but sockmap doesn't intercept
non-TCP to attach strparser. For example, with UDP, although the
read/write handlers are replaced, strparser is not executed due to the
lack of read_sock operation.

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

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

Signed-off-by: Jiayuan Chen <mrpre@163.com>
---
 net/core/sock_map.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Jakub Sitnicki Jan. 21, 2025, 2:23 p.m. UTC | #1
On Tue, Jan 21, 2025 at 01:07 PM +08, Jiayuan Chen wrote:
> Currently, only TCP supports strparser, but sockmap doesn't intercept
> non-TCP to attach strparser. For example, with UDP, although the
> read/write handlers are replaced, strparser is not executed due to the
> lack of read_sock operation.
>
> Furthermore, in udp_bpf_recvmsg(), it checks whether psock has data, and
> if not, it falls back to the native UDP read interface, making
> UDP + strparser appear to read correctly. According to it's commit

Nit: typo, "its"

> history, the behavior is unexpected.
>
> Moreover, since UDP lacks the concept of streams, we intercept it
> directly.
>
> 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);

Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
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Patch

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);