bpf, selftests: Add test case for mixed cgroup v1/v2

Minimal selftest which implements a small BPF policy program to the
connect(2) hook which rejects TCP connection requests to port 60123
with EPERM. This is being attached to a non-root cgroup v2 path. The
test asserts that this works under cgroup v2-only and under a mixed
cgroup v1/v2 environment where net_classid is set in the former case.

Before fix:

  # ./test_progs -t cgroup_v1v2
  test_cgroup_v1v2:PASS:server_fd 0 nsec
  test_cgroup_v1v2:PASS:client_fd 0 nsec
  test_cgroup_v1v2:PASS:cgroup_fd 0 nsec
  test_cgroup_v1v2:PASS:server_fd 0 nsec
  run_test:PASS:skel_open 0 nsec
  run_test:PASS:prog_attach 0 nsec
  test_cgroup_v1v2:PASS:cgroup-v2-only 0 nsec
  run_test:PASS:skel_open 0 nsec
  run_test:PASS:prog_attach 0 nsec
  run_test:PASS:join_classid 0 nsec
  (network_helpers.c:219: errno: None) Unexpected success to connect to server
  test_cgroup_v1v2:FAIL:cgroup-v1v2 unexpected error: -1 (errno 0)
  #27 cgroup_v1v2:FAIL
  Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED

After fix:

  # ./test_progs -t cgroup_v1v2
  #27 cgroup_v1v2:OK
  Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210913230759.2313-3-daniel@iogearbox.net

diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
index 7e9f637..6db1af8 100644 (file)
--- a/tools/testing/selftests/bpf/network_helpers.c
+++ b/tools/testing/selftests/bpf/network_helpers.c
@@ -208,11 +208,26 @@ error_close:
 
 static int connect_fd_to_addr(int fd,
                              const struct sockaddr_storage *addr,
-                             socklen_t addrlen)
+                             socklen_t addrlen, const bool must_fail)
 {
-       if (connect(fd, (const struct sockaddr *)addr, addrlen)) {
-               log_err("Failed to connect to server");
-               return -1;
+       int ret;
+
+       errno = 0;
+       ret = connect(fd, (const struct sockaddr *)addr, addrlen);
+       if (must_fail) {
+               if (!ret) {
+                       log_err("Unexpected success to connect to server");
+                       return -1;
+               }
+               if (errno != EPERM) {
+                       log_err("Unexpected error from connect to server");
+                       return -1;
+               }
+       } else {
+               if (ret) {
+                       log_err("Failed to connect to server");
+                       return -1;
+               }
        }
 
        return 0;
@@ -257,7 +272,7 @@ int connect_to_fd_opts(int server_fd, const struct network_helper_opts *opts)
                       strlen(opts->cc) + 1))
                goto error_close;
 
-       if (connect_fd_to_addr(fd, &addr, addrlen))
+       if (connect_fd_to_addr(fd, &addr, addrlen, opts->must_fail))
                goto error_close;
 
        return fd;
@@ -289,7 +304,7 @@ int connect_fd_to_fd(int client_fd, int server_fd, int timeout_ms)
                return -1;
        }
 
-       if (connect_fd_to_addr(client_fd, &addr, len))
+       if (connect_fd_to_addr(client_fd, &addr, len, false))
                return -1;
 
        return 0;

diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h
index da7e132..d198181 100644 (file)
--- a/tools/testing/selftests/bpf/network_helpers.h
+++ b/tools/testing/selftests/bpf/network_helpers.h
@@ -20,6 +20,7 @@ typedef __u16 __sum16;
 struct network_helper_opts {
        const char *cc;
        int timeout_ms;
+       bool must_fail;
 };
 
 /* ipv4 test vector */

diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_v1v2.c b/tools/testing/selftests/bpf/prog_tests/cgroup_v1v2.c
new file mode 100644 (file)
index 0000000..ab3b9bc
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/cgroup_v1v2.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+
+#include "connect4_dropper.skel.h"
+
+#include "cgroup_helpers.h"
+#include "network_helpers.h"
+
+static int run_test(int cgroup_fd, int server_fd, bool classid)
+{
+       struct network_helper_opts opts = {
+               .must_fail = true,
+       };
+       struct connect4_dropper *skel;
+       int fd, err = 0;
+
+       skel = connect4_dropper__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "skel_open"))
+               return -1;
+
+       skel->links.connect_v4_dropper =
+               bpf_program__attach_cgroup(skel->progs.connect_v4_dropper,
+                                          cgroup_fd);
+       if (!ASSERT_OK_PTR(skel->links.connect_v4_dropper, "prog_attach")) {
+               err = -1;
+               goto out;
+       }
+
+       if (classid && !ASSERT_OK(join_classid(), "join_classid")) {
+               err = -1;
+               goto out;
+       }
+
+       fd = connect_to_fd_opts(server_fd, &opts);
+       if (fd < 0)
+               err = -1;
+       else
+               close(fd);
+out:
+       connect4_dropper__destroy(skel);
+       return err;
+}
+
+void test_cgroup_v1v2(void)
+{
+       struct network_helper_opts opts = {};
+       int server_fd, client_fd, cgroup_fd;
+       static const int port = 60123;
+
+       /* Step 1: Check base connectivity works without any BPF. */
+       server_fd = start_server(AF_INET, SOCK_STREAM, NULL, port, 0);
+       if (!ASSERT_GE(server_fd, 0, "server_fd"))
+               return;
+       client_fd = connect_to_fd_opts(server_fd, &opts);
+       if (!ASSERT_GE(client_fd, 0, "client_fd")) {
+               close(server_fd);
+               return;
+       }
+       close(client_fd);
+       close(server_fd);
+
+       /* Step 2: Check BPF policy prog attached to cgroups drops connectivity. */
+       cgroup_fd = test__join_cgroup("/connect_dropper");
+       if (!ASSERT_GE(cgroup_fd, 0, "cgroup_fd"))
+               return;
+       server_fd = start_server(AF_INET, SOCK_STREAM, NULL, port, 0);
+       if (!ASSERT_GE(server_fd, 0, "server_fd")) {
+               close(cgroup_fd);
+               return;
+       }
+       ASSERT_OK(run_test(cgroup_fd, server_fd, false), "cgroup-v2-only");
+       setup_classid_environment();
+       set_classid(42);
+       ASSERT_OK(run_test(cgroup_fd, server_fd, true), "cgroup-v1v2");
+       cleanup_classid_environment();
+       close(server_fd);
+       close(cgroup_fd);
+}

diff --git a/tools/testing/selftests/bpf/progs/connect4_dropper.c b/tools/testing/selftests/bpf/progs/connect4_dropper.c
new file mode 100644 (file)
index 0000000..b565d99
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/connect4_dropper.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <string.h>
+
+#include <linux/stddef.h>
+#include <linux/bpf.h>
+
+#include <sys/socket.h>
+
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+
+#define VERDICT_REJECT 0
+#define VERDICT_PROCEED        1
+
+SEC("cgroup/connect4")
+int connect_v4_dropper(struct bpf_sock_addr *ctx)
+{
+       if (ctx->type != SOCK_STREAM)
+               return VERDICT_PROCEED;
+       if (ctx->user_port == bpf_htons(60123))
+               return VERDICT_REJECT;
+       return VERDICT_PROCEED;
+}
+
+char _license[] SEC("license") = "GPL";