Pin down the two contracts changed by the companion patch. LINK_UPDATE validates a replacement program against the link's attach type, while CGROUP_SKB capability checks apply at LINK_CREATE and not LINK_UPDATE.
Cover incompatible UDP4/UDP6 and LSM attach flavors, plus a CGROUP_SKB link update after dropping CAP_NET_ADMIN and CAP_SYS_ADMIN. Signed-off-by: Sanghyun Park <[email protected]> --- v5: - Isolate attach and update coverage in separate subtests with their own setup. - Inline the one-use LSM program FD and use a descriptive link FD. - Explain the create-versus-update contracts covered by the tests. v4: https://lore.kernel.org/r/[email protected] --- .../selftests/bpf/prog_tests/cgroup_link.c | 81 ++++++++++++++++++- .../selftests/bpf/prog_tests/lsm_cgroup.c | 12 +++ .../testing/selftests/bpf/progs/lsm_cgroup.c | 6 ++ .../selftests/bpf/progs/test_cgroup_link.c | 14 +++- 4 files changed, 111 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_link.c b/tools/testing/selftests/bpf/prog_tests/cgroup_link.c index 15093a69510e..3b43c34917cc 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 <test_progs.h> +#include "cap_helpers.h" #include "cgroup_helpers.h" #include "testing_helpers.h" #include "test_cgroup_link.skel.h" @@ -24,7 +25,77 @@ int ping_and_check(int exp_calls, int exp_alt_calls) return 0; } -void serial_test_cgroup_link(void) +static void test_cgroup_link_update(void) +{ + const __u64 caps = (1ULL << CAP_NET_ADMIN) | (1ULL << CAP_SYS_ADMIN); + struct bpf_link *link = NULL; + __u64 saved_caps = 0; + int cg_fd = -1, err; + + skel = test_cgroup_link__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_open_load")) + return; + + err = setup_cgroup_environment(); + if (!ASSERT_OK(err, "cg_init")) + goto cleanup; + + cg_fd = create_and_get_cgroup("/cgroup_link_update"); + if (!ASSERT_GE(cg_fd, 0, "cg_create")) + goto cleanup; + + err = join_cgroup("/cgroup_link_update"); + if (!ASSERT_OK(err, "cg_join")) + goto cleanup; + + 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); + if (cg_fd >= 0) + close(cg_fd); + cleanup_cgroup_environment(); + test_cgroup_link__destroy(skel); + skel = NULL; +} + +static void test_cgroup_link_attach(void) { struct { const char *path; @@ -253,3 +324,11 @@ void serial_test_cgroup_link(void) } cleanup_cgroup_environment(); } + +void serial_test_cgroup_link(void) +{ + if (test__start_subtest("attach")) + test_cgroup_link_attach(); + if (test__start_subtest("update")) + test_cgroup_link_update(); +} diff --git a/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c b/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c index 41e867467f6c..0dd44dbb9c95 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 socket_link_fd = -1; int err, fd, prio; socklen_t socklen; @@ -156,6 +157,17 @@ 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"); + socket_link_fd = + bpf_link_create(bpf_program__fd(skel->progs.socket_first), + cgroup_fd, BPF_LSM_CGROUP, NULL); + if (!ASSERT_GE(socket_link_fd, 0, "link create socket_first")) + goto detach_cgroup; + err = bpf_link_update(socket_link_fd, + bpf_program__fd(skel->progs.socket_create_lsm), + NULL); + ASSERT_EQ(err, -EINVAL, "reject lsm_mac link update"); + close(socket_link_fd); + /* Attach another instance of bind program to another cgroup. * This should trigger the reuse of the trampoline shim (two * programs attaching to the same btf_id). diff --git a/tools/testing/selftests/bpf/progs/lsm_cgroup.c b/tools/testing/selftests/bpf/progs/lsm_cgroup.c index 3bfa479104be..30727945cecc 100644 --- a/tools/testing/selftests/bpf/progs/lsm_cgroup.c +++ b/tools/testing/selftests/bpf/progs/lsm_cgroup.c @@ -213,6 +213,12 @@ int BPF_PROG(socket_first, int family, int type, int protocol, int kern) return 0; } +SEC("lsm/socket_create") +int BPF_PROG(socket_create_lsm, int family, int type, int protocol, int kern) +{ + return 0; +} + SEC("lsm_cgroup/socket_create") int BPF_PROG(socket_second, int family, int type, int protocol, int kern) { diff --git a/tools/testing/selftests/bpf/progs/test_cgroup_link.c b/tools/testing/selftests/bpf/progs/test_cgroup_link.c index 4faba88e45a5..a987744d129c 100644 --- a/tools/testing/selftests/bpf/progs/test_cgroup_link.c +++ b/tools/testing/selftests/bpf/progs/test_cgroup_link.c @@ -20,5 +20,17 @@ int egress_alt(struct __sk_buff *skb) return 1; } -char _license[] SEC("license") = "GPL"; +SEC("cgroup/sendmsg4") +int sendmsg4(struct bpf_sock_addr *ctx) +{ + return 1; +} +SEC("cgroup/sendmsg6") +int sendmsg6(struct bpf_sock_addr *ctx) +{ + ctx->msg_src_ip6[2] = 0; + return 1; +} + +char _license[] SEC("license") = "GPL"; -- 2.48.1
