5.4-stable review patch. If anyone has any objections, please let me know.
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From: Jiayuan Chen jiayuan.chen@linux.dev
[ Upstream commit 178f6a5c8cb3b6be1602de0964cd440243f493c9 ]
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 xiyou.wangcong@gmail.com Signed-off-by: Jiayuan Chen jiayuan.chen@linux.dev Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: John Fastabend john.fastabend@gmail.com Acked-by: Jakub Kicinski kuba@kernel.org Link: https://lore.kernel.org/bpf/20250609020910.397930-2-jiayuan.chen@linux.dev Signed-off-by: Sasha Levin sashal@kernel.org --- net/tls/tls_sw.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index 432bce329392..8dabbbf52168 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -822,6 +822,19 @@ 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. + */ + struct sk_msg *enc = &ctx->open_rec->msg_encrypted; + + sk_msg_trim(sk, enc, enc->sg.size - delta); + } } if (msg->cork_bytes && msg->cork_bytes > msg->sg.size && !enospc && !full_record) {