From nobody Sat Jun 20 14:11:41 2026 Received: from out-174.mta1.migadu.com (out-174.mta1.migadu.com [95.215.58.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 864DA3CF689 for ; Tue, 14 Apr 2026 11:24:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.174 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776165853; cv=none; b=MidLL9HoMkfSZSPKL7WwEAV9zvolISRrEy8uaZeXJOG1HfvUWg3HbuYtaE8yHxmGvDL+R++7HC8g9vrTuat5Ebao6MYcAA0so8+H6B4PzihASStwFwvftvZcRQe2aL5fhtZq4YkY12vxjuVQPzmL0e3aU86JZqbWkPIwutxu1o8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776165853; c=relaxed/simple; bh=hmsqy4cV2LA86UGh87Xqb0jXa1P+m8YQHKjlqn5mTEU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XwASw8LxEsA6NgNWkSJHLIs3Fc10j+9Df5i5NMtS5q0WhHDg+dEaRNQybKRmJY99aZqLsuubHlvdtZcs69m6lzWC2A5lMLssOI6Ij7yfLHHYZ+pTrfqRP9gsVxnHnU38jaReAZOJCI81oJyTBrjNidkbjoz59DB4HVw2+1F4GpQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Bzm7PEnX; arc=none smtp.client-ip=95.215.58.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Bzm7PEnX" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1776165849; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8D6l9IqgXenCYoi0Zzds89afKEXhHv1Gdqt5MlYQ8P0=; b=Bzm7PEnXtbS1ZFhPk5sBnr9bC0pzse8lilkNeecuWcgm7+fTqLlH9X19uykVXSda/sKwY0 LIwHBoe2TSHRrq9A3sLBcPK5HZ6ScpPCUZExBhTlXt61AHHbur18X4oKy3ebDnp0RM3fr2 Ye7aZoMU/+fa4hmmShnTAr8cexjhW3I= From: KaFai Wan To: edumazet@google.com, ncardwell@google.com, kuniyu@google.com, davem@davemloft.net, dsahern@kernel.org, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, shuah@kernel.org, kafai.wan@linux.dev, sdf@fomichev.me, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Quan Sun <2022090917019@std.uestc.edu.cn>, Yinhao Hu , Kaiyan Mei Subject: [PATCH bpf-next 1/2] bpf: tcp: Reject TCP_NODELAY from BPF hdr opt callbacks Date: Tue, 14 Apr 2026 19:23:09 +0800 Message-ID: <20260414112310.1285783-2-kafai.wan@linux.dev> In-Reply-To: <20260414112310.1285783-1-kafai.wan@linux.dev> References: <20260414112310.1285783-1-kafai.wan@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" A BPF_SOCK_OPS program can enable BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG and then call bpf_setsockopt(TCP_NODELAY) from BPF_SOCK_OPS_HDR_OPT_LEN_CB. That reaches __tcp_sock_set_nodelay(), which may call tcp_push_pending_frames(). The transmit path then computes TCP options again, re-enters bpf_skops_hdr_opt_len(), and invokes the same BPF callback recursively. This can loop until the kernel stack overflows. TCP_NODELAY is not safe from the header option callback context. Reject it with -EOPNOTSUPP when TCP header option callbacks are enabled on the socket, so the callback cannot recurse back into tcp_push_pending_frames() through do_tcp_setsockopt(). Reported-by: Quan Sun <2022090917019@std.uestc.edu.cn> Reported-by: Yinhao Hu Reported-by: Kaiyan Mei Closes: https://lore.kernel.org/bpf/d1d523c9-6901-4454-a183-94462b8f3e4e@st= d.uestc.edu.cn/ Fixes: 7e41df5dbba2 ("bpf: Add a few optnames to bpf_setsockopt") Signed-off-by: KaFai Wan --- net/ipv4/tcp.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 202a4e57a218..7ac4c98be19d 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -4004,7 +4004,10 @@ int do_tcp_setsockopt(struct sock *sk, int level, in= t optname, =20 switch (optname) { case TCP_NODELAY: - __tcp_sock_set_nodelay(sk, val); + if (val && BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG= )) + err =3D -EOPNOTSUPP; + else + __tcp_sock_set_nodelay(sk, val); break; =20 case TCP_THIN_LINEAR_TIMEOUTS: --=20 2.43.0 From nobody Sat Jun 20 14:11:41 2026 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F107F3939A2 for ; Tue, 14 Apr 2026 11:24:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.188 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776165862; cv=none; b=Vro156DzRHWJEseRuR76MvuAA/hGTIiWh9ysu7BGwuRF/a2fFsTH82KLdr5PBx0ufGlvFOhyEVUfYzPOv5anhtPD4NvuRBz6IqpFP/X234tF83xhoFS6YutPL0mDPSQlTGUNvkHt0xsYPpsSfMUzlMA/Rdrfhs0QCRJzUiyiwgo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776165862; c=relaxed/simple; bh=0XKwPrVsLYqMkdidCVFKYLqUJ4c4EfyJ1ob1+L0+szc=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MAVUfk9DURlmaPA+zfy/o4XB1Lbb5HjGpaU4NRYo+vRWRIgDI5kGj/NO3/zIevbQ2VzOl9beu15bGvn0L56MmQcagVUhgfCnZ/zs1FRH+1nLug+o4JpR4td1LrZqnSjXzTTgSTor4eGFQPoGC4nh0hooD+G17Hu9sWL2XNGPP2E= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=xI+6m4mw; arc=none smtp.client-ip=95.215.58.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="xI+6m4mw" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1776165859; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9yPm78UqHyZkm1QqrS3WLRW2slYckpyvj6iqSa7dJaU=; b=xI+6m4mw4iR24mWikEbqUbtnMYM5+ZpcfMM5M6FbhOQ4Uufl8H2/De2LPdo8YObnMU+8Ud 8Z2Ami6lZae5H3ObtR+5Ex8+w/cyMVqW7NSK4cZ7tjfp+iKINoDXYnJqAchxvk38DA+ZxR 9EAsw2MiFlpnwzkFoGHnYiv6jAeT5rI= From: KaFai Wan To: edumazet@google.com, ncardwell@google.com, kuniyu@google.com, davem@davemloft.net, dsahern@kernel.org, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, shuah@kernel.org, kafai.wan@linux.dev, sdf@fomichev.me, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf-next 2/2] selftests/bpf: Cover TCP_NODELAY in hdr opt callback Date: Tue, 14 Apr 2026 19:23:10 +0800 Message-ID: <20260414112310.1285783-3-kafai.wan@linux.dev> In-Reply-To: <20260414112310.1285783-1-kafai.wan@linux.dev> References: <20260414112310.1285783-1-kafai.wan@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" Add a sockops test program that enables BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG on connection setup and calls bpf_setsockopt(TCP_NODELAY) from BPF_SOCK_OPS_HDR_OPT_LEN_CB. Exercise the connection by sending data after the socket is established. Before the fix, this setup can recurse through tcp_push_pending_frames() and bpf_skops_hdr_opt_len() until the kernel hits a stack guard page. After the fix, the connection continues to make forward progress and the data exchange completes. Signed-off-by: KaFai Wan --- .../bpf/prog_tests/tcp_hdr_options.c | 34 +++++++++++++++++++ .../bpf/progs/test_misc_tcp_hdr_options.c | 18 ++++++++++ 2 files changed, 52 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/tcp_hdr_options.c b/too= ls/testing/selftests/bpf/prog_tests/tcp_hdr_options.c index 56685fc03c7e..f361f9c7bf59 100644 --- a/tools/testing/selftests/bpf/prog_tests/tcp_hdr_options.c +++ b/tools/testing/selftests/bpf/prog_tests/tcp_hdr_options.c @@ -513,6 +513,39 @@ static void misc(void) bpf_link__destroy(link); } =20 +static void hdr_sockopt(void) +{ + const char send_msg[] =3D "MISC!!!"; + char recv_msg[sizeof(send_msg)]; + const unsigned int nr_data =3D 2; + struct bpf_link *link; + struct sk_fds sk_fds; + int i, ret; + + link =3D bpf_program__attach_cgroup(misc_skel->progs.misc_hdr_sockopt, cg= _fd); + if (!ASSERT_OK_PTR(link, "attach_cgroup(misc_hdr_sockopt)")) + return; + + if (sk_fds_connect(&sk_fds, false)) { + bpf_link__destroy(link); + return; + } + + for (i =3D 0; i < nr_data; i++) { + ret =3D send(sk_fds.active_fd, send_msg, sizeof(send_msg), 0); + if (!ASSERT_EQ(ret, sizeof(send_msg), "send(msg)")) + goto check_linum; + + ret =3D read(sk_fds.passive_fd, recv_msg, sizeof(recv_msg)); + if (!ASSERT_EQ(ret, sizeof(send_msg), "read(msg)")) + goto check_linum; + } + +check_linum: + sk_fds_close(&sk_fds); + bpf_link__destroy(link); +} + struct test { const char *desc; void (*run)(void); @@ -526,6 +559,7 @@ static struct test tests[] =3D { DEF_TEST(fastopen_estab), DEF_TEST(fin), DEF_TEST(misc), + DEF_TEST(hdr_sockopt), }; =20 void test_tcp_hdr_options(void) diff --git a/tools/testing/selftests/bpf/progs/test_misc_tcp_hdr_options.c = b/tools/testing/selftests/bpf/progs/test_misc_tcp_hdr_options.c index d487153a839d..e1dc7246193e 100644 --- a/tools/testing/selftests/bpf/progs/test_misc_tcp_hdr_options.c +++ b/tools/testing/selftests/bpf/progs/test_misc_tcp_hdr_options.c @@ -326,4 +326,22 @@ int misc_estab(struct bpf_sock_ops *skops) return CG_OK; } =20 +SEC("sockops") +int misc_hdr_sockopt(struct bpf_sock_ops *skops) +{ + int true_val =3D 1; + + switch (skops->op) { + case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: + case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: + set_hdr_cb_flags(skops, 0); + break; + case BPF_SOCK_OPS_HDR_OPT_LEN_CB: + bpf_setsockopt(skops, SOL_TCP, TCP_NODELAY, &true_val, sizeof(true_val)); + break; + } + + return 0; +} + char _license[] SEC("license") =3D "GPL"; --=20 2.43.0