From nobody Fri Jun 19 22:15:55 2026 Received: from out-171.mta1.migadu.com (out-171.mta1.migadu.com [95.215.58.171]) (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 90DA4364038 for ; Tue, 21 Apr 2026 15:59:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.171 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776787161; cv=none; b=Pzitr3Ws+iq5QOOWN1cktgp81PsmJ/ByJtuHyAu9k5IIAZ9BQAvJqAiRWxvgGCyPwRSCO8ZVdwSA+1jSNDULqiSAnKCwGy4PtfDLZRd/ktNkjibjW8SxsX5EzFzd4DRP1O+4Ye0rSMC9zaJt7QLXxW0Te497NldmapuQgBa037A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776787161; c=relaxed/simple; bh=MASmzLLYx8bP7k5KvtnKIA/J9TSasL0lOIuwGyJ/+7g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BJs62EajFNXveP1Aozmmf+aVU8BmfULa9vt6mtgFMtzDr9q6jo64U4PHM3ffX4M/QJ6CXnUMgQL85M0pdH0mNu7/0qe3IyQuEsa+hL0zMP0MZjh7eEWKoea9iZTTalWHDBekar3JRbx6VVSXKs3r3EUG4XCf6dF7OsiKwkIVp3M= 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=DWyyV3jM; arc=none smtp.client-ip=95.215.58.171 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="DWyyV3jM" 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=1776787157; 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=4FXbVn3w1/0ZWZKtjjV1fGo1JJvX0eigdezJlZf0mPI=; b=DWyyV3jMcOMdC0EmdqPxblY+4mvPESGFDAqc+ig3S481VnOVlcQq8ps3g66z8vJHJ4hn2P 1JHKrBX6mWHNYGOENSq7DL7NhkF+7gFJd2/REPcFdpNIUhppUNjVO6GHOiqxHOcBr4/6qT 2vdSvsqGbo97DTQ7DORzzTROtnt58dk= From: KaFai Wan To: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, sdf@fomichev.me, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, dsahern@kernel.org, shuah@kernel.org, ihor.solodrai@linux.dev, kafai.wan@linux.dev, jiayuan.chen@linux.dev, hoyeon.lee@suse.com, ameryhung@gmail.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Quan Sun <2022090917019@std.uestc.edu.cn>, Yinhao Hu , Kaiyan Mei Subject: [PATCH bpf-next v4 1/4] bpf: Reject TCP_NODELAY in TCP header option callbacks Date: Tue, 21 Apr 2026 23:58:01 +0800 Message-ID: <20260421155804.135786-2-kafai.wan@linux.dev> In-Reply-To: <20260421155804.135786-1-kafai.wan@linux.dev> References: <20260421155804.135786-1-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") Reviewed-by: Jiayuan Chen Signed-off-by: KaFai Wan --- 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 Fri Jun 19 22:15:55 2026 Received: from out-176.mta1.migadu.com (out-176.mta1.migadu.com [95.215.58.176]) (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 675663624AB for ; Tue, 21 Apr 2026 15:59:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.176 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776787173; cv=none; b=nKY6JIFAtzkS7rovW0FItbt6xn5/WaRujCvuLAu4raF/gSLpzE6LdTbUvS8pIeiZ55tyn9W4j3oIdfHG0/8kKxuIWFQElab0kR1pxXieLv8CIspV9FHpC+2CiOs6JI1m/SIsp+XALH4bua1xZ9sVKC2QFSC/1Ujq/eQmtPOrILk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776787173; c=relaxed/simple; bh=3hSh3lFXbFSbrMW9IaKB5o2WHPIwz1DAomU7Hz2Ubwg=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WDreCSCV24PaKc6L7ohIWOMjfW2iQCo4tJ9Ivfu4PiFWCzRdnnH0qgiuzSse+fpGBQZR+iy4gCo49Q5AfMlM0ZJTxbqOhzgb8N2j+VEcUNsazePNQrwK+s4X88757rXSDi/xlXdyvlY2un5RtxpiKXMnddm4XTJMJT2PL1Xu0gM= 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=dXwGyR4q; arc=none smtp.client-ip=95.215.58.176 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="dXwGyR4q" 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=1776787170; 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=x3E/jslnq568lIXr1RHFQ4heGbZ1dbw/jYSVYgE8kqw=; b=dXwGyR4qw6xlhwShrrRLocyNpS3JKKBB748aO0Yr7w9EnBzbixYMt/k1rY0jugp101Pdj5 9ho34v23h0q8OjNq6WAC9nTZvuqC7gpi6+z03cdA/64eKRpqgRJmTMLRP1tI+hx4n99NtC mOf/VxUV/l4iqMEXfHeTn7iiq0l7eGs= From: KaFai Wan To: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, sdf@fomichev.me, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, dsahern@kernel.org, shuah@kernel.org, ihor.solodrai@linux.dev, kafai.wan@linux.dev, jiayuan.chen@linux.dev, hoyeon.lee@suse.com, ameryhung@gmail.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf-next v4 2/4] bpf: Reject TCP_NODELAY in bpf-tcp-cc Date: Tue, 21 Apr 2026 23:58:02 +0800 Message-ID: <20260421155804.135786-3-kafai.wan@linux.dev> In-Reply-To: <20260421155804.135786-1-kafai.wan@linux.dev> References: <20260421155804.135786-1-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 TCP congestion control program can call bpf_setsockopt() from its callbacks. In current kernels, if it calls bpf_setsockopt(TCP_NODELAY) from cwnd_event_tx_start(), the call can re-enter the TCP transmit path before the outer tcp_transmit_skb() has completed and advanced the send head. This can re-trigger CA_EVENT_TX_START and lead to unbounded recursion: tcp_transmit_skb() -> tcp_event_data_sent() -> tcp_ca_event(sk, CA_EVENT_TX_START) -> cwnd_event_tx_start() -> bpf_setsockopt(TCP_NODELAY) -> tcp_push_pending_frames() -> tcp_write_xmit() -> tcp_transmit_skb() This leads to unbounded recursion and can overflow the kernel stack. Reject TCP_NODELAY with -EOPNOTSUPP for bpf-tcp-cc by introducing a dedicated setsockopt proto for BPF_PROG_TYPE_STRUCT_OPS TCP congestion control programs. Fixes: 7e41df5dbba2 ("bpf: Add a few optnames to bpf_setsockopt") Suggested-by: Martin KaFai Lau Signed-off-by: KaFai Wan Reviewed-by: Jiayuan Chen --- include/linux/bpf.h | 1 + net/core/filter.c | 24 ++++++++++++++++++++++++ net/ipv4/bpf_tcp_ca.c | 2 +- 3 files changed, 26 insertions(+), 1 deletion(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 3cb6b9e70080..cf75da8a12bd 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -3725,6 +3725,7 @@ extern const struct bpf_func_proto bpf_for_each_map_e= lem_proto; extern const struct bpf_func_proto bpf_btf_find_by_name_kind_proto; extern const struct bpf_func_proto bpf_sk_setsockopt_proto; extern const struct bpf_func_proto bpf_sk_getsockopt_proto; +extern const struct bpf_func_proto bpf_sk_setsockopt_nodelay_proto; extern const struct bpf_func_proto bpf_unlocked_sk_setsockopt_proto; extern const struct bpf_func_proto bpf_unlocked_sk_getsockopt_proto; extern const struct bpf_func_proto bpf_find_vma_proto; diff --git a/net/core/filter.c b/net/core/filter.c index 96849f4c1fbc..1140f4b55ab5 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5688,6 +5688,30 @@ const struct bpf_func_proto bpf_sk_getsockopt_proto = =3D { .arg5_type =3D ARG_CONST_SIZE, }; =20 +BPF_CALL_5(bpf_sk_setsockopt_nodelay, struct sock *, sk, int, level, + int, optname, char *, optval, int, optlen) +{ + /* + * TCP_NODELAY triggers tcp_push_pending_frames() and re-enters + * CA_EVENT_TX_START in bpf_tcp_cc, reject it in all bpf_tcp_cc. + */ + if (level =3D=3D SOL_TCP && optname =3D=3D TCP_NODELAY) + return -EOPNOTSUPP; + + return _bpf_setsockopt(sk, level, optname, optval, optlen); +} + +const struct bpf_func_proto bpf_sk_setsockopt_nodelay_proto =3D { + .func =3D bpf_sk_setsockopt_nodelay, + .gpl_only =3D false, + .ret_type =3D RET_INTEGER, + .arg1_type =3D ARG_PTR_TO_BTF_ID_SOCK_COMMON, + .arg2_type =3D ARG_ANYTHING, + .arg3_type =3D ARG_ANYTHING, + .arg4_type =3D ARG_PTR_TO_MEM | MEM_RDONLY, + .arg5_type =3D ARG_CONST_SIZE, +}; + BPF_CALL_5(bpf_unlocked_sk_setsockopt, struct sock *, sk, int, level, int, optname, char *, optval, int, optlen) { diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c index 008edc7f6688..791e15063237 100644 --- a/net/ipv4/bpf_tcp_ca.c +++ b/net/ipv4/bpf_tcp_ca.c @@ -168,7 +168,7 @@ bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, */ if (prog_ops_moff(prog) !=3D offsetof(struct tcp_congestion_ops, release)) - return &bpf_sk_setsockopt_proto; + return &bpf_sk_setsockopt_nodelay_proto; return NULL; case BPF_FUNC_getsockopt: /* Since get/setsockopt is usually expected to --=20 2.43.0 From nobody Fri Jun 19 22:15:55 2026 Received: from out-172.mta1.migadu.com (out-172.mta1.migadu.com [95.215.58.172]) (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 B93E0363082 for ; Tue, 21 Apr 2026 15:59:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776787186; cv=none; b=EN7rjbPf2056OeTz4rfPfF6KTz82mUVzjjLtfBzzluYKPuUoadDKfHyvWxagHBkIx5EuPasNLob511/5YMOccxR2UULsSKR9G7Uahjvnn+o2CySxIjQvXN9SVPYs3xwjoazQ799cSZDT3hVCHJ17MxUVSM6bB9x3WPLrnGJ2G38= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776787186; c=relaxed/simple; bh=jmlhbGs2XEQ0YVEdPg2DhM9HBiM8Cev4qjA75thKJbc=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rsoN0b6zFdlz9CcN9d3IsRv2Q2X221JcBhZagAQik4R6/O+6wQ5NysldqqmV2rmoXGc6V6JGdkSTy2S/+dsbt3rHUcSG9j1642Cxi4vtxMAB/Vaq6FplgrJyBSvfGbotAjBDjav4n6jNfWs7HLQcX2dy3yGmBqgT2yW/cNEswcw= 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=LtHsRblZ; arc=none smtp.client-ip=95.215.58.172 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="LtHsRblZ" 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=1776787183; 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=qMeS4rzJcZIOSoAT809/HlFM/RGvuB7M1xVMHKcnJ/Y=; b=LtHsRblZ2tpH4N7M8BgjS7cr3iaOjnftJcbVtEQU++kDe3Ox+eE9tuZ6yPoVbSIfmE5P52 TQ0bVLvkYFNblETFFQ8BOhavCoF2T8LNC71MmUlDhZo99OuGDKaKIKt7EUFimh2IPh8MB8 SP6LN4PYAf57bWmD9FJu8EnTJ4PZzSo= From: KaFai Wan To: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, sdf@fomichev.me, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, dsahern@kernel.org, shuah@kernel.org, ihor.solodrai@linux.dev, kafai.wan@linux.dev, jiayuan.chen@linux.dev, hoyeon.lee@suse.com, ameryhung@gmail.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf-next v4 3/4] selftests/bpf: Test TCP_NODELAY in TCP hdr opt callbacks Date: Tue, 21 Apr 2026 23:58:03 +0800 Message-ID: <20260421155804.135786-4-kafai.wan@linux.dev> In-Reply-To: <20260421155804.135786-1-kafai.wan@linux.dev> References: <20260421155804.135786-1-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. Signed-off-by: KaFai Wan Reviewed-by: Jiayuan Chen --- .../selftests/bpf/prog_tests/tcp_hdr_options.c | 6 ++++++ .../bpf/progs/test_misc_tcp_hdr_options.c | 15 ++++++++++++++- 2 files changed, 20 insertions(+), 1 deletion(-) 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..21632e0946c5 100644 --- a/tools/testing/selftests/bpf/prog_tests/tcp_hdr_options.c +++ b/tools/testing/selftests/bpf/prog_tests/tcp_hdr_options.c @@ -507,6 +507,12 @@ static void misc(void) =20 ASSERT_EQ(misc_skel->bss->nr_hwtstamp, 0, "nr_hwtstamp"); =20 + ASSERT_TRUE(misc_skel->data->nodelay_est_ok, "nodelay_est_ok"); + + ASSERT_TRUE(misc_skel->data->nodelay_hdr_len_reject, "nodelay_hdr_len_rej= ect"); + + ASSERT_TRUE(misc_skel->data->nodelay_write_hdr_reject, "nodelay_write_hdr= _reject"); + 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..e77ec6791092 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_reject =3D true; +bool nodelay_write_hdr_reject =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_reject &=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_reject &=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 From nobody Fri Jun 19 22:15:55 2026 Received: from out-180.mta1.migadu.com (out-180.mta1.migadu.com [95.215.58.180]) (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 1B0AB3644CA for ; Tue, 21 Apr 2026 15:59:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.180 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776787198; cv=none; b=gOMdsZ7GBuz/f6fNHGdc1ck0BdhBvXmwFeKAbDOo6S/tMT0y7Nox5ntxWr3MY0Hk0BiuSeRii6R4X/Wi4UBK9rf1Rzehor9NzxkJyB5i0PDP2APUUQpSVy1eLNLMyyya3+YaodTXili9/f6eL5mU6tMpSBHriCJQrNJyssj5I8o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776787198; c=relaxed/simple; bh=SWb2WR4cv0tgGdl6YMq4mlXq+3AHLn9iSZBZQtWSVVE=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bU3oT/xt8tbs4abJuquNUkdgToSQwuVLA+9D75zmN4dqMfLRyJa6YooUcbUeUVqZ53GdOSYOLOL0qptBPhZKFkpeiX0pX4mZL5T+yV9f11J6WJFbubrg0onQeJdN5AYiUrn6UvcvMa5ZYwIMb0sP9VZpVlsinmaqmp4ezoaBf7c= 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=fChs/fI9; arc=none smtp.client-ip=95.215.58.180 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="fChs/fI9" 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=1776787195; 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=s7vdOjflaIY1NUfTHdVQ3+OJuS3RoXj7+ev2ZQFb23E=; b=fChs/fI95OAswnfJx+mWzguYQJEC9vOCZBMM4so0x27mvwZUlFnVYvk/YKdPNGP+ruS2LH G3oXP16K8MCH16FIQW5S9JE19xFHur8A9pMQLDjwYPamEM/eNzOkstndLQPESlOAxw9Ef8 ucYK3SEW/2lvJ5i+1u8T1D+wnkWql6g= From: KaFai Wan To: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, sdf@fomichev.me, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, dsahern@kernel.org, shuah@kernel.org, ihor.solodrai@linux.dev, kafai.wan@linux.dev, jiayuan.chen@linux.dev, hoyeon.lee@suse.com, ameryhung@gmail.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf-next v4 4/4] selftests/bpf: Verify bpf-tcp-cc rejects TCP_NODELAY Date: Tue, 21 Apr 2026 23:58:04 +0800 Message-ID: <20260421155804.135786-5-kafai.wan@linux.dev> In-Reply-To: <20260421155804.135786-1-kafai.wan@linux.dev> References: <20260421155804.135786-1-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 bpf_tcp_ca selftest for the TCP_NODELAY restriction in bpf-tcp-cc. Update bpf_cubic to exercise init() and cwnd_event_tx_start(), and check that both callbacks reject bpf_setsockopt(TCP_NODELAY) with -EOPNOTSUPP. Signed-off-by: KaFai Wan --- tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c | 4 ++++ tools/testing/selftests/bpf/progs/bpf_cubic.c | 12 ++++++++++++ 2 files changed, 16 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c b/tools/te= sting/selftests/bpf/prog_tests/bpf_tcp_ca.c index f829b6f09bc9..4f632aa3a79e 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c @@ -112,6 +112,10 @@ static void test_cubic(void) =20 ASSERT_EQ(cubic_skel->bss->bpf_cubic_acked_called, 1, "pkts_acked called"= ); =20 + ASSERT_TRUE(cubic_skel->data->nodelay_init_reject, "init reject nodelay o= ption"); + ASSERT_TRUE(cubic_skel->data->nodelay_cwnd_event_tx_start_reject, + "cwnd_event_tx_start reject nodelay option"); + bpf_link__destroy(link); bpf_cubic__destroy(cubic_skel); } diff --git a/tools/testing/selftests/bpf/progs/bpf_cubic.c b/tools/testing/= selftests/bpf/progs/bpf_cubic.c index ce18a4db813f..b941ab3ebad5 100644 --- a/tools/testing/selftests/bpf/progs/bpf_cubic.c +++ b/tools/testing/selftests/bpf/progs/bpf_cubic.c @@ -16,6 +16,7 @@ =20 #include "bpf_tracing_net.h" #include +#include =20 char _license[] SEC("license") =3D "GPL"; =20 @@ -170,10 +171,17 @@ static void bictcp_hystart_reset(struct sock *sk) ca->sample_cnt =3D 0; } =20 +bool nodelay_init_reject =3D true; +bool nodelay_cwnd_event_tx_start_reject =3D true; + SEC("struct_ops") void BPF_PROG(bpf_cubic_init, struct sock *sk) { struct bpf_bictcp *ca =3D inet_csk_ca(sk); + int true_val =3D 1, ret; + + ret =3D bpf_setsockopt(sk, SOL_TCP, TCP_NODELAY, &true_val, sizeof(true_v= al)); + nodelay_init_reject &=3D ret =3D=3D -EOPNOTSUPP; =20 bictcp_reset(ca); =20 @@ -189,8 +197,12 @@ void BPF_PROG(bpf_cubic_cwnd_event_tx_start, struct so= ck *sk) { struct bpf_bictcp *ca =3D inet_csk_ca(sk); __u32 now =3D tcp_jiffies32; + int true_val =3D 1, ret; __s32 delta; =20 + ret =3D bpf_setsockopt(sk, SOL_TCP, TCP_NODELAY, &true_val, sizeof(true_v= al)); + nodelay_cwnd_event_tx_start_reject &=3D ret =3D=3D -EOPNOTSUPP; + delta =3D now - tcp_sk(sk)->lsndtime; =20 /* We were application limited (idle) for a while. --=20 2.43.0