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@xxxxxxxxxxxxx>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
tools/testing/selftests/bpf/network_helpers.c | 27 +++++--
tools/testing/selftests/bpf/network_helpers.h | 1 +
.../selftests/bpf/prog_tests/cgroup_v1v2.c | 79 +++++++++++++++++++
.../selftests/bpf/progs/connect4_dropper.c | 26 ++++++
4 files changed, 127 insertions(+), 6 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/cgroup_v1v2.c
create mode 100644 tools/testing/selftests/bpf/progs/connect4_dropper.c
diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
index 7e9f6375757a..6db1af8fdee7 100644
--- a/tools/testing/selftests/bpf/network_helpers.c
+++ b/tools/testing/selftests/bpf/network_helpers.c
@@ -208,11 +208,26 @@ int fastopen_connect(int server_fd, const char *data, unsigned int data_len,
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 da7e132657d5..d198181a5648 100644
--- 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
index 000000000000..ab3b9bc5e6d1
--- /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
index 000000000000..b565d997810a
--- /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";
--
2.27.0
