From bee4b7e6268be9267e288936f5b1215fec3d4368 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Tue, 29 Sep 2020 14:45:57 +0200 Subject: [PATCH] selftests: Add selftest for disallowing modify_return attachment to freplace MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This adds a selftest that ensures that modify_return tracing programs cannot be attached to freplace programs. The security_ prefix is added to the freplace program because that would otherwise let it pass the check for modify_return. Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/160138355713.48470.3811074984255709369.stgit@toke.dk --- .../selftests/bpf/prog_tests/fexit_bpf2bpf.c | 56 +++++++++++++++++++ .../selftests/bpf/progs/fmod_ret_freplace.c | 14 +++++ .../bpf/progs/freplace_get_constant.c | 2 +- 3 files changed, 71 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/progs/fmod_ret_freplace.c diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c index 2b94e827b2c5..5c0448910426 100644 --- a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c +++ b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c @@ -232,6 +232,60 @@ static void test_func_replace_multi(void) prog_name, true, test_second_attach); } +static void test_fmod_ret_freplace(void) +{ + struct bpf_object *freplace_obj = NULL, *pkt_obj, *fmod_obj = NULL; + const char *freplace_name = "./freplace_get_constant.o"; + const char *fmod_ret_name = "./fmod_ret_freplace.o"; + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts); + const char *tgt_name = "./test_pkt_access.o"; + struct bpf_link *freplace_link = NULL; + struct bpf_program *prog; + __u32 duration = 0; + int err, pkt_fd; + + err = bpf_prog_load(tgt_name, BPF_PROG_TYPE_UNSPEC, + &pkt_obj, &pkt_fd); + /* the target prog should load fine */ + if (CHECK(err, "tgt_prog_load", "file %s err %d errno %d\n", + tgt_name, err, errno)) + return; + opts.attach_prog_fd = pkt_fd; + + freplace_obj = bpf_object__open_file(freplace_name, &opts); + if (CHECK(IS_ERR_OR_NULL(freplace_obj), "freplace_obj_open", + "failed to open %s: %ld\n", freplace_name, + PTR_ERR(freplace_obj))) + goto out; + + err = bpf_object__load(freplace_obj); + if (CHECK(err, "freplace_obj_load", "err %d\n", err)) + goto out; + + prog = bpf_program__next(NULL, freplace_obj); + freplace_link = bpf_program__attach_trace(prog); + if (CHECK(IS_ERR(freplace_link), "freplace_attach_trace", "failed to link\n")) + goto out; + + opts.attach_prog_fd = bpf_program__fd(prog); + fmod_obj = bpf_object__open_file(fmod_ret_name, &opts); + if (CHECK(IS_ERR_OR_NULL(fmod_obj), "fmod_obj_open", + "failed to open %s: %ld\n", fmod_ret_name, + PTR_ERR(fmod_obj))) + goto out; + + err = bpf_object__load(fmod_obj); + if (CHECK(!err, "fmod_obj_load", "loading fmod_ret should fail\n")) + goto out; + +out: + bpf_link__destroy(freplace_link); + bpf_object__close(freplace_obj); + bpf_object__close(fmod_obj); + bpf_object__close(pkt_obj); +} + + static void test_func_sockmap_update(void) { const char *prog_name[] = { @@ -314,4 +368,6 @@ void test_fexit_bpf2bpf(void) test_func_map_prog_compatibility(); if (test__start_subtest("func_replace_multi")) test_func_replace_multi(); + if (test__start_subtest("fmod_ret_freplace")) + test_fmod_ret_freplace(); } diff --git a/tools/testing/selftests/bpf/progs/fmod_ret_freplace.c b/tools/testing/selftests/bpf/progs/fmod_ret_freplace.c new file mode 100644 index 000000000000..c8943ccee6c0 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/fmod_ret_freplace.c @@ -0,0 +1,14 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include + +volatile __u64 test_fmod_ret = 0; +SEC("fmod_ret/security_new_get_constant") +int BPF_PROG(fmod_ret_test, long val, int ret) +{ + test_fmod_ret = 1; + return 120; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/freplace_get_constant.c b/tools/testing/selftests/bpf/progs/freplace_get_constant.c index 8f0ecf94e533..705e4b64dfc2 100644 --- a/tools/testing/selftests/bpf/progs/freplace_get_constant.c +++ b/tools/testing/selftests/bpf/progs/freplace_get_constant.c @@ -5,7 +5,7 @@ volatile __u64 test_get_constant = 0; SEC("freplace/get_constant") -int new_get_constant(long val) +int security_new_get_constant(long val) { if (val != 123) return 0; -- 2.20.1