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Message-Id: <20220405214342.1968262-7-sdf@google.com>
Date: Tue, 5 Apr 2022 14:43:41 -0700
From: Stanislav Fomichev <sdf@...gle.com>
To: netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
Stanislav Fomichev <sdf@...gle.com>
Subject: [PATCH bpf-next v2 6/7] selftests/bpf: lsm_cgroup functional test
Functional test that exercises the following:
1. apply default sk_priority policy
2. permit TX-only AF_PACKET socket
3. cgroup attach/detach/replace
4. reusing trampoline shim
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
.../selftests/bpf/prog_tests/lsm_cgroup.c | 158 ++++++++++++++++++
.../testing/selftests/bpf/progs/lsm_cgroup.c | 94 +++++++++++
2 files changed, 252 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c
create mode 100644 tools/testing/selftests/bpf/progs/lsm_cgroup.c
diff --git a/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c b/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c
new file mode 100644
index 000000000000..e786b63d81e2
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c
@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <test_progs.h>
+
+#include "lsm_cgroup.skel.h"
+#include "cgroup_helpers.h"
+
+void test_lsm_cgroup(void)
+{
+ DECLARE_LIBBPF_OPTS(bpf_prog_attach_opts, attach_opts);
+ DECLARE_LIBBPF_OPTS(bpf_link_update_opts, update_opts);
+ int cgroup_fd, cgroup_fd2, err, fd, prio;
+ struct lsm_cgroup *skel = NULL;
+ int post_create_prog_fd2 = -1;
+ int post_create_prog_fd = -1;
+ int bind_link_fd2 = -1;
+ int bind_prog_fd2 = -1;
+ int alloc_prog_fd = -1;
+ int bind_prog_fd = -1;
+ int bind_link_fd = -1;
+ socklen_t socklen;
+
+ cgroup_fd = test__join_cgroup("/sock_policy");
+ if (!ASSERT_GE(cgroup_fd, 0, "join_cgroup"))
+ goto close_skel;
+
+ cgroup_fd2 = create_and_get_cgroup("/sock_policy2");
+ if (!ASSERT_GE(cgroup_fd2, 0, "create second cgroup"))
+ goto close_skel;
+
+ skel = lsm_cgroup__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "open_and_load"))
+ goto close_cgroup;
+
+ post_create_prog_fd = bpf_program__fd(skel->progs.socket_post_create);
+ post_create_prog_fd2 = bpf_program__fd(skel->progs.socket_post_create2);
+ bind_prog_fd = bpf_program__fd(skel->progs.socket_bind);
+ bind_prog_fd2 = bpf_program__fd(skel->progs.socket_bind2);
+ alloc_prog_fd = bpf_program__fd(skel->progs.socket_alloc);
+
+ err = bpf_prog_attach(alloc_prog_fd, cgroup_fd, BPF_LSM_CGROUP, 0);
+ if (!ASSERT_OK(err, "attach alloc_prog_fd"))
+ goto detach_cgroup;
+
+ /* Make sure replacing works.
+ */
+
+ err = bpf_prog_attach(post_create_prog_fd, cgroup_fd,
+ BPF_LSM_CGROUP, 0);
+ if (!ASSERT_OK(err, "attach post_create_prog_fd"))
+ goto close_cgroup;
+
+ attach_opts.replace_prog_fd = post_create_prog_fd;
+ err = bpf_prog_attach_opts(post_create_prog_fd2, cgroup_fd,
+ BPF_LSM_CGROUP, &attach_opts);
+ if (!ASSERT_OK(err, "prog replace post_create_prog_fd"))
+ goto detach_cgroup;
+
+ /* Try the same attach/replace via link API.
+ */
+
+ bind_link_fd = bpf_link_create(bind_prog_fd, cgroup_fd,
+ BPF_LSM_CGROUP, NULL);
+ if (!ASSERT_GE(bind_link_fd, 0, "link create bind_prog_fd"))
+ goto detach_cgroup;
+
+ update_opts.old_prog_fd = bind_prog_fd;
+ update_opts.flags = BPF_F_REPLACE;
+
+ err = bpf_link_update(bind_link_fd, bind_prog_fd2, &update_opts);
+ if (!ASSERT_OK(err, "link update bind_prog_fd"))
+ goto detach_cgroup;
+
+ /* 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).
+ */
+
+ bind_link_fd2 = bpf_link_create(bind_prog_fd2, cgroup_fd2,
+ BPF_LSM_CGROUP, NULL);
+ if (!ASSERT_GE(bind_link_fd2, 0, "link create bind_prog_fd2"))
+ goto detach_cgroup;
+
+ /* AF_UNIX is prohibited.
+ */
+
+ fd = socket(AF_UNIX, SOCK_STREAM, 0);
+ ASSERT_LT(fd, 0, "socket(AF_UNIX)");
+
+ /* AF_INET6 gets default policy (sk_priority).
+ */
+
+ fd = socket(AF_INET6, SOCK_STREAM, 0);
+ if (!ASSERT_GE(fd, 0, "socket(SOCK_STREAM)"))
+ goto detach_cgroup;
+
+ prio = 0;
+ socklen = sizeof(prio);
+ ASSERT_GE(getsockopt(fd, SOL_SOCKET, SO_PRIORITY, &prio, &socklen), 0,
+ "getsockopt");
+ ASSERT_EQ(prio, 123, "sk_priority");
+
+ close(fd);
+
+ /* TX-only AF_PACKET is allowed.
+ */
+
+ ASSERT_LT(socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL)), 0,
+ "socket(AF_PACKET, ..., ETH_P_ALL)");
+
+ fd = socket(AF_PACKET, SOCK_RAW, 0);
+ ASSERT_GE(fd, 0, "socket(AF_PACKET, ..., 0)");
+
+ /* TX-only AF_PACKET can not be rebound.
+ */
+
+ struct sockaddr_ll sa = {
+ .sll_family = AF_PACKET,
+ .sll_protocol = htons(ETH_P_ALL),
+ };
+ ASSERT_LT(bind(fd, (struct sockaddr *)&sa, sizeof(sa)), 0,
+ "bind(ETH_P_ALL)");
+
+ close(fd);
+
+ /* Make sure other cgroup doesn't trigger the programs.
+ */
+
+ if (!ASSERT_OK(join_cgroup(""), "join root cgroup"))
+ goto detach_cgroup;
+
+ fd = socket(AF_INET6, SOCK_STREAM, 0);
+ if (!ASSERT_GE(fd, 0, "socket(SOCK_STREAM)"))
+ goto detach_cgroup;
+
+ prio = 0;
+ socklen = sizeof(prio);
+ ASSERT_GE(getsockopt(fd, SOL_SOCKET, SO_PRIORITY, &prio, &socklen), 0,
+ "getsockopt");
+ ASSERT_EQ(prio, 0, "sk_priority");
+
+ close(fd);
+
+detach_cgroup:
+ ASSERT_GE(bpf_prog_detach2(post_create_prog_fd2, cgroup_fd,
+ BPF_LSM_CGROUP), 0, "detach_create");
+ close(bind_link_fd);
+ /* Don't close bind_link_fd2, exercise cgroup release cleanup. */
+ ASSERT_GE(bpf_prog_detach2(alloc_prog_fd, cgroup_fd,
+ BPF_LSM_CGROUP), 0, "detach_alloc");
+
+close_cgroup:
+ close(cgroup_fd);
+close_skel:
+ lsm_cgroup__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/lsm_cgroup.c b/tools/testing/selftests/bpf/progs/lsm_cgroup.c
new file mode 100644
index 000000000000..fd3b2daa26aa
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/lsm_cgroup.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+#ifndef AF_PACKET
+#define AF_PACKET 17
+#endif
+
+#ifndef AF_UNIX
+#define AF_UNIX 1
+#endif
+
+#ifndef EPERM
+#define EPERM 1
+#endif
+
+static __always_inline int real_create(struct socket *sock, int family,
+ int protocol)
+{
+ struct sock *sk;
+
+ /* Reject non-tx-only AF_PACKET.
+ */
+ if (family == AF_PACKET && protocol != 0)
+ return 0; /* EPERM */
+
+ sk = sock->sk;
+ if (!sk)
+ return 1;
+
+ /* The rest of the sockets get default policy.
+ */
+ sk->sk_priority = 123;
+ return 1;
+}
+
+SEC("lsm_cgroup/socket_post_create")
+int BPF_PROG(socket_post_create, struct socket *sock, int family,
+ int type, int protocol, int kern)
+{
+ return real_create(sock, family, protocol);
+}
+
+SEC("lsm_cgroup/socket_post_create")
+int BPF_PROG(socket_post_create2, struct socket *sock, int family,
+ int type, int protocol, int kern)
+{
+ return real_create(sock, family, protocol);
+}
+
+static __always_inline int real_bind(struct socket *sock,
+ struct sockaddr *address,
+ int addrlen)
+{
+ struct sockaddr_ll sa = {};
+
+ if (sock->sk->__sk_common.skc_family != AF_PACKET)
+ return 1;
+
+ if (sock->sk->sk_kern_sock)
+ return 1;
+
+ bpf_probe_read_kernel(&sa, sizeof(sa), address);
+ if (sa.sll_protocol)
+ return 0; /* EPERM */
+
+ return 1;
+}
+
+SEC("lsm_cgroup/socket_bind")
+int BPF_PROG(socket_bind, struct socket *sock, struct sockaddr *address,
+ int addrlen)
+{
+ return real_bind(sock, address, addrlen);
+}
+
+SEC("lsm_cgroup/socket_bind")
+int BPF_PROG(socket_bind2, struct socket *sock, struct sockaddr *address,
+ int addrlen)
+{
+ return real_bind(sock, address, addrlen);
+}
+
+SEC("lsm_cgroup/sk_alloc_security")
+int BPF_PROG(socket_alloc, struct sock *sk, int family, gfp_t priority)
+{
+ if (family == AF_UNIX)
+ return 0; /* EPERM */
+ return 1;
+}
--
2.35.1.1094.g7c7d902a7c-goog
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