2025/5/30 02:16, "Cong Wang" [off-list ref] 写到:

On Fri, May 23, 2025 at 09:18:58PM +0800, Jiayuan Chen wrote:

quoted

When sending plaintext data, we initially calculated the corresponding

 ciphertext length. However, if we later reduced the plaintext data length

 via socket policy, we failed to recalculate the ciphertext length.

 

 This results in transmitting buffers containing uninitialized data during

 ciphertext transmission.

 

 This causes uninitialized bytes to be appended after a complete

 "Application Data" packet, leading to errors on the receiving end when

 parsing TLS record.

 

 Fixes: d3b18ad31f93 ("tls: add bpf support to sk_msg handling")

 Reported-by: Cong Wang [off-list ref]

 Signed-off-by: Jiayuan Chen [off-list ref]

 ---

 net/tls/tls_sw.c | 15 +++++++++++++++

 1 file changed, 15 insertions(+)

 

 diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c

 index fc88e34b7f33..b23a4655be6a 100644

 --- a/net/tls/tls_sw.c

 +++ b/net/tls/tls_sw.c

 @@ -872,6 +872,21 @@ static int bpf_exec_tx_verdict(struct sk_msg *msg, struct sock *sk,

 delta = msg->sg.size;

 psock->eval = sk_psock_msg_verdict(sk, psock, msg);

 delta -= msg->sg.size;

 +

 + if ((s32)delta > 0) {

 + /* It indicates that we executed bpf_msg_pop_data(),

 + * causing the plaintext data size to decrease.

 + * Therefore the encrypted data size also needs to

 + * correspondingly decrease. We only need to subtract

 + * delta to calculate the new ciphertext length since

 + * ktls does not support block encryption.

 + */

 + if (!WARN_ON_ONCE(!ctx->open_rec)) {

I am wondering if we need to WARN here? Because the code below this

handles it gracefully:

Hi Cong

The ctx->open_rec is freed after a TLS record is processed (regardless
of whether the redirect check passes or triggers a redirect).
The 'if (rec)' check in the subsequent code you print is indeed designed
to handle the expected lifecycle state of open_rec.

But the code path I modified should never see a NULL open_rec under normal
operation As this is a bug fix, I need to ensure the fix itself doesn't
create new issues. 

Thanks.

 931 bool reset_eval = !ctx->open_rec;

 932 

 933 rec = ctx->open_rec;

 934 if (rec) {

 935 msg = &rec->msg_plaintext;

 936 if (!msg->apply_bytes)

 937 reset_eval = true;

 938 }

 939 if (reset_eval) {

 940 psock->eval = __SK_NONE;

 941 if (psock->sk_redir) {

 942 sock_put(psock->sk_redir);

 943 psock->sk_redir = NULL;

 944 }

 945 }

Thanks for fixing it!

Cong