From 543576ec15b17c0c93301ac8297333c7b6e84ac7 Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Fri, 26 Apr 2024 16:16:18 -0700 Subject: [PATCH 1/3] bpf: Add BPF_PROG_TYPE_CGROUP_SKB attach type enforcement in BPF_LINK_CREATE bpf_prog_attach uses attach_type_to_prog_type to enforce proper attach type for BPF_PROG_TYPE_CGROUP_SKB. link_create uses bpf_prog_get and relies on bpf_prog_attach_check_attach_type to properly verify prog_type <> attach_type association. Add missing attach_type enforcement for the link_create case. Otherwise, it's currently possible to attach cgroup_skb prog types to other cgroup hooks. Fixes: af6eea57437a ("bpf: Implement bpf_link-based cgroup BPF program attachment") Link: https://lore.kernel.org/bpf/0000000000004792a90615a1dde0@google.com/ Reported-by: syzbot+838346b979830606c854@syzkaller.appspotmail.com Signed-off-by: Stanislav Fomichev Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20240426231621.2716876-2-sdf@google.com Signed-off-by: Martin KaFai Lau --- kernel/bpf/syscall.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index c287925471f6..cb61d8880dbe 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3985,6 +3985,11 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog, * check permissions at attach time. */ return -EPERM; + + ptype = attach_type_to_prog_type(attach_type); + if (prog->type != ptype) + return -EINVAL; + return prog->enforce_expected_attach_type && prog->expected_attach_type != attach_type ? -EINVAL : 0; From d70b2660e75b85bdaa9d75f9c4224c2f6f89cf23 Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Fri, 26 Apr 2024 16:16:19 -0700 Subject: [PATCH 2/3] selftests/bpf: Extend sockopt tests to use BPF_LINK_CREATE Run all existing test cases with the attachment created via BPF_LINK_CREATE. Next commit will add extra test cases to verify link_create attach_type enforcement. Signed-off-by: Stanislav Fomichev Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20240426231621.2716876-3-sdf@google.com Signed-off-by: Martin KaFai Lau --- .../selftests/bpf/prog_tests/sockopt.c | 25 ++++++++++++++----- 1 file changed, 19 insertions(+), 6 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt.c b/tools/testing/selftests/bpf/prog_tests/sockopt.c index 5a4491d4edfe..dea340996e97 100644 --- a/tools/testing/selftests/bpf/prog_tests/sockopt.c +++ b/tools/testing/selftests/bpf/prog_tests/sockopt.c @@ -1036,9 +1036,10 @@ static int call_getsockopt(bool use_io_uring, int fd, int level, int optname, return getsockopt(fd, level, optname, optval, optlen); } -static int run_test(int cgroup_fd, struct sockopt_test *test, bool use_io_uring) +static int run_test(int cgroup_fd, struct sockopt_test *test, bool use_io_uring, + bool use_link) { - int sock_fd, err, prog_fd; + int sock_fd, err, prog_fd, link_fd = -1; void *optval = NULL; int ret = 0; @@ -1051,7 +1052,12 @@ static int run_test(int cgroup_fd, struct sockopt_test *test, bool use_io_uring) return -1; } - err = bpf_prog_attach(prog_fd, cgroup_fd, test->attach_type, 0); + if (use_link) { + err = bpf_link_create(prog_fd, cgroup_fd, test->attach_type, NULL); + link_fd = err; + } else { + err = bpf_prog_attach(prog_fd, cgroup_fd, test->attach_type, 0); + } if (err < 0) { if (test->error == DENY_ATTACH) goto close_prog_fd; @@ -1142,7 +1148,12 @@ free_optval: close_sock_fd: close(sock_fd); detach_prog: - bpf_prog_detach2(prog_fd, cgroup_fd, test->attach_type); + if (use_link) { + if (link_fd >= 0) + close(link_fd); + } else { + bpf_prog_detach2(prog_fd, cgroup_fd, test->attach_type); + } close_prog_fd: close(prog_fd); return ret; @@ -1160,10 +1171,12 @@ void test_sockopt(void) if (!test__start_subtest(tests[i].descr)) continue; - ASSERT_OK(run_test(cgroup_fd, &tests[i], false), + ASSERT_OK(run_test(cgroup_fd, &tests[i], false, false), + tests[i].descr); + ASSERT_OK(run_test(cgroup_fd, &tests[i], false, true), tests[i].descr); if (tests[i].io_uring_support) - ASSERT_OK(run_test(cgroup_fd, &tests[i], true), + ASSERT_OK(run_test(cgroup_fd, &tests[i], true, false), tests[i].descr); } From 095ddb501b39b7842e5da555915ad89e370b9888 Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Fri, 26 Apr 2024 16:16:20 -0700 Subject: [PATCH 3/3] selftests/bpf: Add sockopt case to verify prog_type Make sure only sockopt programs can be attached to the setsockopt and getsockopt hooks. Signed-off-by: Stanislav Fomichev Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20240426231621.2716876-4-sdf@google.com Signed-off-by: Martin KaFai Lau --- .../selftests/bpf/prog_tests/sockopt.c | 40 ++++++++++++++++++- 1 file changed, 38 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt.c b/tools/testing/selftests/bpf/prog_tests/sockopt.c index dea340996e97..eaac83a7f388 100644 --- a/tools/testing/selftests/bpf/prog_tests/sockopt.c +++ b/tools/testing/selftests/bpf/prog_tests/sockopt.c @@ -24,6 +24,7 @@ enum sockopt_test_error { static struct sockopt_test { const char *descr; const struct bpf_insn insns[64]; + enum bpf_prog_type prog_type; enum bpf_attach_type attach_type; enum bpf_attach_type expected_attach_type; @@ -928,9 +929,40 @@ static struct sockopt_test { .error = EPERM_SETSOCKOPT, }, + + /* ==================== prog_type ==================== */ + + { + .descr = "can attach only BPF_CGROUP_SETSOCKOP", + .insns = { + /* return 1 */ + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_EXIT_INSN(), + + }, + .prog_type = BPF_PROG_TYPE_CGROUP_SKB, + .attach_type = BPF_CGROUP_SETSOCKOPT, + .expected_attach_type = 0, + .error = DENY_ATTACH, + }, + + { + .descr = "can attach only BPF_CGROUP_GETSOCKOP", + .insns = { + /* return 1 */ + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_EXIT_INSN(), + + }, + .prog_type = BPF_PROG_TYPE_CGROUP_SKB, + .attach_type = BPF_CGROUP_GETSOCKOPT, + .expected_attach_type = 0, + .error = DENY_ATTACH, + }, }; static int load_prog(const struct bpf_insn *insns, + enum bpf_prog_type prog_type, enum bpf_attach_type expected_attach_type) { LIBBPF_OPTS(bpf_prog_load_opts, opts, @@ -947,7 +979,7 @@ static int load_prog(const struct bpf_insn *insns, } insns_cnt++; - fd = bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCKOPT, NULL, "GPL", insns, insns_cnt, &opts); + fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts); if (verbose && fd < 0) fprintf(stderr, "%s\n", bpf_log_buf); @@ -1039,11 +1071,15 @@ static int call_getsockopt(bool use_io_uring, int fd, int level, int optname, static int run_test(int cgroup_fd, struct sockopt_test *test, bool use_io_uring, bool use_link) { + int prog_type = BPF_PROG_TYPE_CGROUP_SOCKOPT; int sock_fd, err, prog_fd, link_fd = -1; void *optval = NULL; int ret = 0; - prog_fd = load_prog(test->insns, test->expected_attach_type); + if (test->prog_type) + prog_type = test->prog_type; + + prog_fd = load_prog(test->insns, prog_type, test->expected_attach_type); if (prog_fd < 0) { if (test->error == DENY_LOAD) return 0;