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Message-ID: <aDika2FRd4n+VRmZ@pop-os.localdomain>
Date: Thu, 29 May 2025 11:16:11 -0700
From: Cong Wang <xiyou.wangcong@...il.com>
To: Jiayuan Chen <jiayuan.chen@...ux.dev>
Cc: bpf@...r.kernel.org, Boris Pismenny <borisp@...dia.com>,
John Fastabend <john.fastabend@...il.com>,
Jakub Kicinski <kuba@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
Simon Horman <horms@...nel.org>,
Andrii Nakryiko <andrii@...nel.org>,
Eduard Zingerman <eddyz87@...il.com>,
Mykola Lysenko <mykolal@...com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>,
Yonghong Song <yonghong.song@...ux.dev>,
KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>,
Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
Shuah Khan <shuah@...nel.org>, Ihor Solodrai <isolodrai@...a.com>,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org
Subject: Re: [PATCH bpf-next v1 1/2] bpf,ktls: Fix data corruption when using
bpf_msg_pop_data() in ktls
On Fri, May 23, 2025 at 09:18:58PM +0800, Jiayuan Chen wrote:
> 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@...il.com>
> Signed-off-by: Jiayuan Chen <jiayuan.chen@...ux.dev>
> ---
> 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:
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
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