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[2a01:cb08:8949:7e00:b5a0:44c6:307a:465e]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4505238e174sm13608738f8f.1.2026.05.06.09.05.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 May 2026 09:05:50 -0700 (PDT) Date: Wed, 6 May 2026 18:05:48 +0200 From: Paul Chaignon To: Paul Houssel Cc: paul.houssel@orange.com, Andrii Nakryiko , Yonghong Song , KP Singh , Alexei Starovoitov , Song Liu , Martin KaFai Lau , Christian =?iso-8859-1?Q?K=F6nig?= , Florian Westphal , "T.J. Mercier" , Li RongQing , "D. Wythe" , Jakub Kicinski , Stanislav Fomichev , bpf@vger.kernel.org Subject: Re: [PATCH v3 2/2] selftests/bpf: add tests to verify the enforcement of CONFIG_CGROUP_LSM_NUM Message-ID: References: <20260506150547.767315-1-paulhoussel2@gmail.com> <20260506150547.767315-3-paulhoussel2@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260506150547.767315-3-paulhoussel2@gmail.com> On Wed, May 06, 2026 at 05:05:47PM +0200, Paul Houssel wrote: > Add a selftest that verifies the kernel correctly enforces > CONFIG_CGROUP_LSM_NUM as the maximum number of concurrently attachable > per-cgroup LSM hook slots. > > The BPF program side (progs/cgroup_lsm_num.c) defines 12 lsm_cgroup > programs, each attached to a distinct LSM hook. The test side > (prog_tests/cgroup_lsm_num.c) attempts to attach all 12 programs one by > one to a cgroup, and verifies that exactly 10 succeed and 2 are rejected, > matching the value of CONFIG_CGROUP_LSM_NUM set to 10 in the selftest > Kconfig fragment. > > Signed-off-by: Paul Houssel > --- > tools/testing/selftests/bpf/config | 1 + > .../selftests/bpf/prog_tests/cgroup_lsm_num.c | 60 +++++++++++++++++++ > .../selftests/bpf/progs/cgroup_lsm_num.c | 46 ++++++++++++++ > 3 files changed, 107 insertions(+) > create mode 100644 tools/testing/selftests/bpf/prog_tests/cgroup_lsm_num.c > create mode 100644 tools/testing/selftests/bpf/progs/cgroup_lsm_num.c > > diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config > index 24855381290d..e4c5dd86c640 100644 > --- a/tools/testing/selftests/bpf/config > +++ b/tools/testing/selftests/bpf/config > @@ -11,6 +11,7 @@ CONFIG_BPF_STREAM_PARSER=y > CONFIG_BPF_SYSCALL=y > # CONFIG_BPF_UNPRIV_DEFAULT_OFF is not set > CONFIG_CGROUP_BPF=y > +CONFIG_CGROUP_LSM_NUM=10 > CONFIG_CRYPTO_HMAC=y > CONFIG_CRYPTO_SHA256=y > CONFIG_CRYPTO_USER_API=y > diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_lsm_num.c b/tools/testing/selftests/bpf/prog_tests/cgroup_lsm_num.c > new file mode 100644 > index 000000000000..1c5825c6c3d0 > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/cgroup_lsm_num.c > @@ -0,0 +1,60 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2026 Orange */ > + > +/* > + * Test that the kernel enforces CONFIG_CGROUP_LSM_NUM as the maximum > + * number of concurrently used per-cgroup LSM hook slots. > + * > + * - load a BPF object with 12 programs each on a distinct lsm_cgroup hook > + * - attach them one by one via bpf_program__attach_cgroup() > + * - at some point the slots are exhausted and attachment fails > + * - verify that 10 succeed attachment and 2 fail > + */ > + > +#include > +#include > + > +#include "cgroup_lsm_num.skel.h" > +#include "cgroup_helpers.h" > + > +void test_cgroup_lsm_num(void) > +{ > + struct cgroup_lsm_num *skel = NULL; > + struct bpf_program *prog; > + int cgroup_fd = -1; > + int attached = 0; > + int failed = 0; > + > + cgroup_fd = test__join_cgroup("/cgroup_lsm_num"); > + if (!ASSERT_GE(cgroup_fd, 0, "join_cgroup")) > + return; > + > + skel = cgroup_lsm_num__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "open_and_load")) > + goto out; > + > + bpf_object__for_each_program(prog, skel->obj) { > + struct bpf_link *link; > + > + link = bpf_program__attach_cgroup(prog, cgroup_fd); > + if (!link) { > + if (errno == EOPNOTSUPP) { > + test__skip(); > + goto out; > + } > + failed++; > + } else { > + attached++; > + } > + } > + > + // CONFIG_CGROUP_LSM_NUM set to 10 > + // -> 10 programs shall be attached > + ASSERT_EQ(attached, 10, "at least one attached"); > + // -> 2 programs shall be rejected > + ASSERT_EQ(failed, 2, "limit was enforced"); > + > +out: > + close(cgroup_fd); > + cgroup_lsm_num__destroy(skel); > +} > diff --git a/tools/testing/selftests/bpf/progs/cgroup_lsm_num.c b/tools/testing/selftests/bpf/progs/cgroup_lsm_num.c > new file mode 100644 > index 000000000000..662aee2283c2 > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/cgroup_lsm_num.c > @@ -0,0 +1,46 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2026 Orange */ > + > +/* > + * 12 LSM programs with lsm_cgroup attachment type, each on a distinct LSM > + * hook. Used by prog_tests/cgroup_lsm_num.c to verify that the kernel > + * enforces the CONFIG_CGROUP_LSM_NUM limit on unique per-cgroup LSM hook > + * slots. With CONFIG_CGROUP_LSM_NUM set to 10, 10 shall be attached and 2 > + * rejected. > + */ > + > +#include "vmlinux.h" > +#include > +#include > + > +char _license[] SEC("license") = "GPL"; > + > +#define LSM_CGROUP_HOOK(name, hook) \ > + SEC("lsm_cgroup/" #hook) \ > + int BPF_PROG(name) { return 1; } > + > + > +LSM_CGROUP_HOOK(hook0, socket_create) > + > +LSM_CGROUP_HOOK(hook1, socket_post_create) > + > +LSM_CGROUP_HOOK(hook2, socket_socketpair) > + > +LSM_CGROUP_HOOK(hook3, socket_bind) > + > +LSM_CGROUP_HOOK(hook4, socket_connect) > + > +LSM_CGROUP_HOOK(hook5, socket_listen) > + > +LSM_CGROUP_HOOK(hook6, socket_accept) > + > +LSM_CGROUP_HOOK(hook7, socket_sendmsg) > + > +LSM_CGROUP_HOOK(hook8, socket_recvmsg) > + > +LSM_CGROUP_HOOK(hook9, socket_getsockname) > + > +LSM_CGROUP_HOOK(hook10, socket_getpeername) > + > +LSM_CGROUP_HOOK(hook11, socket_shutdown) Please remove all the unnecessary newlines. One empty line after the macro definition is enough :) > + > -- > 2.54.0 >