From nobody Tue Jun 16 04:58:24 2026 Received: from out-178.mta0.migadu.com (out-178.mta0.migadu.com [91.218.175.178]) (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 060593AF665 for ; Fri, 17 Apr 2026 09:21:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776417670; cv=none; b=om0tIr0enFSqpR8a0TAR4+gARhSe9iO8EdHOKBKrJFkgqmbOi5mY8CrJ/ZXh2tn0bsumwhotX/655JpoC7hH2bxyiGXg0dUXuB4qNFG11aEI+VQQTtmplzCLvCWnl1Ey3aNvmgZTh5fREx2nfw/Nzj3UYSnvIs6u3IuR/jr9XGA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776417670; c=relaxed/simple; bh=p+kb8a+1NUeM4zSYS3PkTA3ZNeUXeZVAEsUWKhViPG8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=q/J6kHKl5JFlgbq4dcfwHyNwJALIiWQPp0d2cE4ok2o5Yj1RvFuaHgaXsKU+1BC2YD1D3NoynrSMTMSMriJlmunN1AHw4KF89DyHUPyZBJcoLaSCgFyAVVq2O5TDdC+51qoLon4TYWTnoiuAO6r7w9Zte76KHuVhV4cEECcXXcg= 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=cGAfW0LZ; arc=none smtp.client-ip=91.218.175.178 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="cGAfW0LZ" 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=1776417665; 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=aApQ4BnXH/mvehRPOqxUVM/gIH07lZCfXG1pxvKAvo4=; b=cGAfW0LZw7+tflTPECEYh0sDsnJlrgjoBRJmrZwq+DDoi5Lki9D+TZhS2HG8QTMOxGHi4b qJN4F3bl13gOyD29ruC9Wk2V3zu2C4jRCVSvFp4CID1ghMvSZy/CQWStOKBfppZH4f8F8v V9WyFUII/nermPDdu+v85TXw6NOCcXA= From: KaFai Wan To: martin.lau@linux.dev, daniel@iogearbox.net, john.fastabend@gmail.com, sdf@fomichev.me, ast@kernel.org, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, shuah@kernel.org, jiayuan.chen@linux.dev, kafai.wan@linux.dev, bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Quan Sun <2022090917019@std.uestc.edu.cn>, Yinhao Hu , Kaiyan Mei Subject: [PATCH bpf v3 1/2] bpf: Reject TCP_NODELAY in TCP header option callbacks Date: Fri, 17 Apr 2026 17:20:34 +0800 Message-ID: <20260417092035.2299913-2-kafai.wan@linux.dev> In-Reply-To: <20260417092035.2299913-1-kafai.wan@linux.dev> References: <20260417092035.2299913-1-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 or BPF_SOCK_OPS_WRITE_HDR_OPT_CB. In these callbacks, bpf_setsockopt(TCP_NODELAY) can reach __tcp_sock_set_nodelay(), which can call tcp_push_pending_frames(). From BPF_SOCK_OPS_HDR_OPT_LEN_CB, tcp_push_pending_frames() can call tcp_current_mss(), which calls tcp_established_options() and re-enters bpf_skops_hdr_opt_len(). BPF_SOCK_OPS_HDR_OPT_LEN_CB -> bpf_setsockopt(TCP_NODELAY) -> tcp_push_pending_frames() -> tcp_current_mss() -> tcp_established_options() -> bpf_skops_hdr_opt_len() -> BPF_SOCK_OPS_HDR_OPT_LEN_CB From BPF_SOCK_OPS_WRITE_HDR_OPT_CB, tcp_push_pending_frames() can call tcp_write_xmit(), which calls tcp_transmit_skb(). That path recomputes header option length through tcp_established_options() and bpf_skops_hdr_opt_len() before re-entering bpf_skops_write_hdr_opt(). BPF_SOCK_OPS_WRITE_HDR_OPT_CB -> bpf_setsockopt(TCP_NODELAY) -> tcp_push_pending_frames() -> tcp_write_xmit() -> tcp_transmit_skb() -> tcp_established_options() -> bpf_skops_hdr_opt_len() -> bpf_skops_write_hdr_opt() -> BPF_SOCK_OPS_WRITE_HDR_OPT_CB This leads to unbounded recursion and can overflow the kernel stack. Reject TCP_NODELAY with -EOPNOTSUPP in bpf_sock_ops_setsockopt() when bpf_setsockopt() is called from BPF_SOCK_OPS_HDR_OPT_LEN_CB or BPF_SOCK_OPS_WRITE_HDR_OPT_CB. 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 Reviewed-by: Jiayuan Chen --- net/core/filter.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/core/filter.c b/net/core/filter.c index 5fa9189eb772..96849f4c1fbc 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5833,6 +5833,12 @@ BPF_CALL_5(bpf_sock_ops_setsockopt, struct bpf_sock_= ops_kern *, bpf_sock, if (!is_locked_tcp_sock_ops(bpf_sock)) return -EOPNOTSUPP; =20 + /* TCP_NODELAY triggers tcp_push_pending_frames() and re-enters these cal= lbacks. */ + if ((bpf_sock->op =3D=3D BPF_SOCK_OPS_HDR_OPT_LEN_CB || + bpf_sock->op =3D=3D BPF_SOCK_OPS_WRITE_HDR_OPT_CB) && + level =3D=3D SOL_TCP && optname =3D=3D TCP_NODELAY) + return -EOPNOTSUPP; + return _bpf_setsockopt(bpf_sock->sk, level, optname, optval, optlen); } =20 --=20 2.43.0 From nobody Tue Jun 16 04:58:24 2026 Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [91.218.175.174]) (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 6781E3B5303 for ; Fri, 17 Apr 2026 09:21:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.174 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776417679; cv=none; b=YUuMW/b7rq4xWjf2oGk7raGyAQeOgYFiwKR30AtpF4bOltYIQZRPY0WXEn5HYHrbxlLU56nm+nX+BQFXrn8/Mwp2y6oSlQ9iRu3u+oAnvX58Xi8Y0CxzLAmXo7xF0OdB9SnRgDahssYTFCYbpH6FffCw3WBXw8xS1FyFijqTbkA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776417679; c=relaxed/simple; bh=M6ErwwDPUWYN/stgA9KjTyOFuDDepXWfSieVtMbfiIE=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=N2GND+RoDtHnWABBWxiogJEsOGAu5dtYYCIY+QvdiErghXaMeNcQYZFny8A/UjI14LBcHuBATdMZoAAx82TDZQRHHZKKZH6afhffUVz2d916+pC+ykCNWW/oSlulDA66RiMbm5mUIa6OiL+9LVFPZbJVrbXxbdwHo3FcJmhwvss= 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=jq8U88dj; arc=none smtp.client-ip=91.218.175.174 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="jq8U88dj" 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=1776417673; 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=q7l7fufO2xt/WoYOZ4wD7hIr19kUg279ukInRFdUToo=; b=jq8U88djAv55h31U43KcrgH5i+vZWxwyBDgaYAPFt7qs2MoTbn5knw/LiGGmlz5iNPpLkm MUTggw17haZVU/IFGFp5Qht6DfdzngzjCb8dwpIot/5yZCLVCKGKgCdq7AQbejxKmWNV/5 aux1TmMKNRKkBis9krKWNti0FUqO38s= From: KaFai Wan To: martin.lau@linux.dev, daniel@iogearbox.net, john.fastabend@gmail.com, sdf@fomichev.me, ast@kernel.org, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, shuah@kernel.org, jiayuan.chen@linux.dev, kafai.wan@linux.dev, bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf v3 2/2] selftests/bpf: Test TCP_NODELAY in TCP hdr opt callbacks Date: Fri, 17 Apr 2026 17:20:35 +0800 Message-ID: <20260417092035.2299913-3-kafai.wan@linux.dev> In-Reply-To: <20260417092035.2299913-1-kafai.wan@linux.dev> References: <20260417092035.2299913-1-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 selftest for the TCP_NODELAY restriction in BPF_SOCK_OPS_HDR_OPT_LEN_CB and BPF_SOCK_OPS_WRITE_HDR_OPT_CB. With BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG enabled, bpf_setsockopt(TCP_NODELAY) returns -EOPNOTSUPP from BPF_SOCK_OPS_HDR_OPT_LEN_CB and BPF_SOCK_OPS_WRITE_HDR_OPT_CB, avoiding unbounded recursion and kernel stack overflow. Other cases continue to work as before, including BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB and user space setsockopt(TCP_NODELAY). Signed-off-by: KaFai Wan Reviewed-by: Jiayuan Chen --- .../selftests/bpf/prog_tests/tcp_hdr_options.c | 12 +++++++++++- .../bpf/progs/test_misc_tcp_hdr_options.c | 15 ++++++++++++++- 2 files changed, 25 insertions(+), 2 deletions(-) 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..7b9dbbb84316 100644 --- a/tools/testing/selftests/bpf/prog_tests/tcp_hdr_options.c +++ b/tools/testing/selftests/bpf/prog_tests/tcp_hdr_options.c @@ -461,7 +461,7 @@ static void misc(void) const unsigned int nr_data =3D 2; struct bpf_link *link; struct sk_fds sk_fds; - int i, ret; + int i, ret, true_val =3D 1; =20 lport_linum_map_fd =3D bpf_map__fd(misc_skel->maps.lport_linum_map); =20 @@ -477,6 +477,10 @@ static void misc(void) return; } =20 + ret =3D setsockopt(sk_fds.active_fd, SOL_TCP, TCP_NODELAY, &true_val, siz= eof(true_val)); + if (!ASSERT_OK(ret, "setsockopt(TCP_NODELAY)")) + goto check_linum; + for (i =3D 0; i < nr_data; i++) { /* MSG_EOR to ensure skb will not be combined */ ret =3D send(sk_fds.active_fd, send_msg, sizeof(send_msg), @@ -507,6 +511,12 @@ static void misc(void) =20 ASSERT_EQ(misc_skel->bss->nr_hwtstamp, 0, "nr_hwtstamp"); =20 + ASSERT_TRUE(misc_skel->data->nodelay_est_ok, "unexpected nodelay_est_ok"); + + ASSERT_TRUE(misc_skel->data->nodelay_hdr_len_err, "unexpected nodelay_hdr= _len_err"); + + ASSERT_TRUE(misc_skel->data->nodelay_write_hdr_err, "unexpected nodelay_w= rite_hdr_err"); + check_linum: ASSERT_FALSE(check_error_linum(&sk_fds), "check_error_linum"); sk_fds_close(&sk_fds); 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..a02e28d9db2e 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 @@ -29,6 +29,10 @@ unsigned int nr_syn =3D 0; unsigned int nr_fin =3D 0; unsigned int nr_hwtstamp =3D 0; =20 +bool nodelay_est_ok =3D true; +bool nodelay_hdr_len_err =3D true; +bool nodelay_write_hdr_err =3D true; + /* Check the header received from the active side */ static int __check_active_hdr_in(struct bpf_sock_ops *skops, bool check_sy= n) { @@ -300,7 +304,7 @@ static int handle_passive_estab(struct bpf_sock_ops *sk= ops) SEC("sockops") int misc_estab(struct bpf_sock_ops *skops) { - int true_val =3D 1; + int true_val =3D 1, false_val =3D 0, ret; =20 switch (skops->op) { case BPF_SOCK_OPS_TCP_LISTEN_CB: @@ -316,10 +320,19 @@ int misc_estab(struct bpf_sock_ops *skops) case BPF_SOCK_OPS_PARSE_HDR_OPT_CB: return handle_parse_hdr(skops); case BPF_SOCK_OPS_HDR_OPT_LEN_CB: + ret =3D bpf_setsockopt(skops, SOL_TCP, TCP_NODELAY, &true_val, sizeof(tr= ue_val)); + nodelay_hdr_len_err &=3D ret =3D=3D -EOPNOTSUPP; + return handle_hdr_opt_len(skops); case BPF_SOCK_OPS_WRITE_HDR_OPT_CB: + ret =3D bpf_setsockopt(skops, SOL_TCP, TCP_NODELAY, &true_val, sizeof(tr= ue_val)); + nodelay_write_hdr_err &=3D ret =3D=3D -EOPNOTSUPP; + return handle_write_hdr_opt(skops); case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: + ret =3D bpf_setsockopt(skops, SOL_TCP, TCP_NODELAY, &false_val, sizeof(f= alse_val)); + nodelay_est_ok &=3D ret =3D=3D 0; + return handle_passive_estab(skops); } =20 --=20 2.43.0