From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-56.mta0.migadu.com [91.218.175.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9BE4E393DDC for ; Mon, 31 Aug 2026 14:51:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788187871; cv=none; b=hpEeZXXqrOvbyqfPfBpsztfeGFFsq8pnU0QVEDxzPomQYPcemJaYmXDe4EQqz9sLV6ITMI6nSal67vESC+qqw4ubVYMAfuLRJMqWcX2srTLMPWSpn8Z64cZhBtIjRXh+Jn1NgVjeDCXtJM4dJpixVFPtPnil5AC39JzAgyW7poM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788187871; c=relaxed/simple; bh=MP66j0Lj+vPv+9cNySgh/2g4Hk6Zg/qh+664HpT8ajw=; h=Message-ID:Date:MIME-Version:From:Subject:To:Cc:References: In-Reply-To:Content-Type; b=GNI4pvoGzXMv5yMpHGIeXv7PBn/AXcUYrNQ+4om5iYWhWtMZblz8w9EIYBx2FufbkNUeEF3aOZWdOuBpCTsCbv1ZHTGeC81YQMkGpG7woijpzfs7RockSJf1z1gPMlUEk024ffZWT3cTjH9+H6lSE+mD+4jPv87JvQBV2TfqSt0= 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=BTr1ZMg+; arc=none smtp.client-ip=91.218.175.56 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="BTr1ZMg+" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=MP66j0Lj+vPv+9cNySgh/2g4Hk6Zg/qh+664HpT8ajw=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788187866; v=1; x=1788792666; b=BTr1ZMg+O9IVbjHMeR45LNWyEI+I7K2Q3yF5rNuhxkcF4FT+BpviIsVnYf1nE6qR83stN8qY XbFvrAiIT0bPP6uCuMahJTZetFMfAZi4UiGu38fOB44e9h1r6m2la3ubqofXWnjtkZ3IPgypEcS upl/4CDQAdrDxDfvze2RZ/7U= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id beb5f4ff7dae3ab5; Mon, 31 Aug 2026 14:50:56 +0000 X-Mizu-Trace-ID: beb5f4ff7dae3ab5 X-Migadu-Flow: FLOW_OUT Message-ID: <425e1052-5c0b-4c0b-8f99-03d90c096ba5@linux.dev> Date: Mon, 31 Aug 2026 22:50:48 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Leon Hwang Subject: Re: [PATCH bpf-next v4 2/2] selftests/bpf: Cover attach type checks in link update To: Sanghyun Park , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , bpf@vger.kernel.org Cc: John Fastabend , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , Shuah Khan , Stanislav Fomichev , Pu Lehui , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20260831023918.1857658-1-sanghyun.park.cnu@gmail.com> <20260831023918.1857658-2-sanghyun.park.cnu@gmail.com> Content-Language: en-US In-Reply-To: <20260831023918.1857658-2-sanghyun.park.cnu@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2026/8/31 10:39, Sanghyun Park wrote: > Add regression coverage for link update compatibility. Verify that a UDP6 > sock_addr program cannot replace a UDP4 program and that an LSM_MAC > program cannot replace an LSM_CGROUP program. > > Also verify that CGROUP_SKB attachment still requires CAP_NET_ADMIN, while > an existing link can be updated after dropping CAP_NET_ADMIN and > CAP_SYS_ADMIN. > > Signed-off-by: Sanghyun Park > --- > .../selftests/bpf/prog_tests/cgroup_link.c | 51 +++++++++++++++++++ > .../selftests/bpf/prog_tests/lsm_cgroup.c | 10 ++++ > .../testing/selftests/bpf/progs/lsm_cgroup.c | 6 +++ > .../selftests/bpf/progs/test_cgroup_link.c | 14 ++++- > 4 files changed, 80 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_link.c b/tools/testing/selftests/bpf/prog_tests/cgroup_link.c > index 15093a69510e..b3219314596e 100644 > --- a/tools/testing/selftests/bpf/prog_tests/cgroup_link.c > +++ b/tools/testing/selftests/bpf/prog_tests/cgroup_link.c > @@ -1,6 +1,7 @@ > // SPDX-License-Identifier: GPL-2.0 > > #include > +#include "cap_helpers.h" > #include "cgroup_helpers.h" > #include "testing_helpers.h" > #include "test_cgroup_link.skel.h" > @@ -24,6 +25,55 @@ int ping_and_check(int exp_calls, int exp_alt_calls) > return 0; > } > > +static void test_cgroup_link_update(int cg_fd) > +{ > + const __u64 caps = (1ULL << CAP_NET_ADMIN) | (1ULL << CAP_SYS_ADMIN); > + struct bpf_link *link = NULL; > + __u64 saved_caps = 0; > + int err; > + > + link = bpf_program__attach_cgroup(skel->progs.sendmsg4, cg_fd); > + if (!ASSERT_OK_PTR(link, "attach_sendmsg4")) > + goto cleanup; > + > + err = bpf_link__update_program(link, skel->progs.sendmsg6); > + ASSERT_EQ(err, -EINVAL, "reject_sendmsg6_update"); > + bpf_link__destroy(link); > + link = NULL; > + > + err = cap_disable_effective(caps, &saved_caps); > + if (!ASSERT_OK(err, "drop_caps_for_attach")) > + goto cleanup; > + > + link = bpf_program__attach_cgroup(skel->progs.egress, cg_fd); > + if (!ASSERT_ERR_PTR(link, "attach_without_net_admin")) > + goto cleanup; > + err = libbpf_get_error(link); > + link = NULL; > + if (!ASSERT_EQ(err, -EPERM, "attach_err")) > + goto cleanup; > + > + err = cap_enable_effective(saved_caps & caps, NULL); > + if (!ASSERT_OK(err, "restore_caps_for_attach")) > + goto cleanup; > + > + link = bpf_program__attach_cgroup(skel->progs.egress, cg_fd); > + if (!ASSERT_OK_PTR(link, "attach_egress")) > + goto cleanup; > + > + err = cap_disable_effective(caps, &saved_caps); > + if (!ASSERT_OK(err, "drop_caps")) > + goto cleanup; > + > + err = bpf_link__update_program(link, skel->progs.egress_alt); > + ASSERT_OK(err, "update_without_net_admin"); > + > +cleanup: > + err = cap_enable_effective(saved_caps & caps, NULL); > + ASSERT_OK(err, "restore_caps"); > + bpf_link__destroy(link); > +} > + > void serial_test_cgroup_link(void) > { > struct { > @@ -61,6 +111,7 @@ void serial_test_cgroup_link(void) > err = join_cgroup(cgs[last_cg].path); > if (CHECK(err, "cg_join", "fail: %d\n", err)) > goto cleanup; > + test_cgroup_link_update(cgs[last_cg].fd); imo, it is not a good idea to embed test_cgroup_link_update() here. Better to add it as a subtest with its own env setup/cleanup: static void test_cgroup_link_attach(void) { /* previous serial_test_cgroup_link() function body */ } static void test_cgroup_link_update(void) { /* setup its own skel and cg env */ /* test link_update */ /* cleanup the skel and cg env */ } void serial_test_cgroup_link(void) { if (test__start_subtest("attach")) test_cgroup_link_attach(); if (test__start_subtest("update")) test_cgroup_link_update(); } > > for (i = 0; i < cg_nr; i++) { > links[i] = bpf_program__attach_cgroup(skel->progs.egress, > diff --git a/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c b/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c > index 41e867467f6c..85b0af4f486a 100644 > --- a/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c > +++ b/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c > @@ -74,6 +74,7 @@ static void test_lsm_cgroup_functional(void) > int bind_prog_fd = -1; > int bind_link_fd = -1; > int clone_prog_fd = -1; > + int mac_prog_fd; > int err, fd, prio; > socklen_t socklen; > > @@ -156,6 +157,15 @@ static void test_lsm_cgroup_functional(void) > ASSERT_EQ(query_prog_cnt(cgroup_fd, "bpf_lsm_socket_bind"), 1, "prog count"); > ASSERT_EQ(query_prog_cnt(cgroup_fd, NULL), 4, "total prog count"); > > + fd = bpf_link_create(bpf_program__fd(skel->progs.socket_first), > + cgroup_fd, BPF_LSM_CGROUP, NULL); > + if (!ASSERT_GE(fd, 0, "link create socket_first")) > + goto detach_cgroup; > + mac_prog_fd = bpf_program__fd(skel->progs.socket_create_lsm); > + err = bpf_link_update(fd, mac_prog_fd, NULL); Rewrite to bpf_link_update(fd, bpf_program__fd(skel->progs.socket_create_lsm), NULL). Then, the 'mac_prog_fd' can be dropped. Thanks, Leon > + ASSERT_EQ(err, -EINVAL, "reject lsm_mac link update");> + close(fd); > [...]