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Subject[PATCH bpf-next 2/2] bpf: Add a selftest for the tracing bpf_get_socket_cookie
Date
This builds up on the existing socket cookie test which checks whether
the bpf_get_socket_cookie helpers provide the same value in
cgroup/connect6 and sockops programs for a socket created by the
userspace part of the test.

Adding a tracing program to the existing objects requires a different
attachment strategy and different headers.

Signed-off-by: Florent Revest <revest@google.com>
---
.../selftests/bpf/progs/socket_cookie_prog.c | 41 ++++++++++++++++---
.../selftests/bpf/test_socket_cookie.c | 18 +++++---
2 files changed, 49 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/socket_cookie_prog.c b/tools/testing/selftests/bpf/progs/socket_cookie_prog.c
index 0cb5656a22b0..a11026aeaaf1 100644
--- a/tools/testing/selftests/bpf/progs/socket_cookie_prog.c
+++ b/tools/testing/selftests/bpf/progs/socket_cookie_prog.c
@@ -1,11 +1,13 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2018 Facebook

-#include <linux/bpf.h>
-#include <sys/socket.h>
+#include "vmlinux.h"

#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
+#include <bpf/bpf_tracing.h>
+
+#define AF_INET6 10

struct socket_cookie {
__u64 cookie_key;
@@ -19,6 +21,14 @@ struct {
__type(value, struct socket_cookie);
} socket_cookies SEC(".maps");

+/*
+ * These three programs get executed in a row on connect() syscalls. The
+ * userspace side of the test creates a client socket, issues a connect() on it
+ * and then checks that the local storage associated with this socket has:
+ * cookie_value == local_port << 8 | 0xFF
+ * The different parts of this cookie_value are appended by those hooks if they
+ * all agree on the output of bpf_get_socket_cookie().
+ */
SEC("cgroup/connect6")
int set_cookie(struct bpf_sock_addr *ctx)
{
@@ -32,14 +42,14 @@ int set_cookie(struct bpf_sock_addr *ctx)
if (!p)
return 1;

- p->cookie_value = 0xFF;
+ p->cookie_value = 0xF;
p->cookie_key = bpf_get_socket_cookie(ctx);

return 1;
}

SEC("sockops")
-int update_cookie(struct bpf_sock_ops *ctx)
+int update_cookie_sockops(struct bpf_sock_ops *ctx)
{
struct bpf_sock *sk;
struct socket_cookie *p;
@@ -60,11 +70,32 @@ int update_cookie(struct bpf_sock_ops *ctx)
if (p->cookie_key != bpf_get_socket_cookie(ctx))
return 1;

- p->cookie_value = (ctx->local_port << 8) | p->cookie_value;
+ p->cookie_value |= (ctx->local_port << 8);

return 1;
}

+SEC("fexit/inet_stream_connect")
+int BPF_PROG(update_cookie_tracing, struct socket *sock,
+ struct sockaddr *uaddr, int addr_len, int flags)
+{
+ struct socket_cookie *p;
+
+ if (uaddr->sa_family != AF_INET6)
+ return 0;
+
+ p = bpf_sk_storage_get(&socket_cookies, sock->sk, 0, 0);
+ if (!p)
+ return 0;
+
+ if (p->cookie_key != bpf_get_socket_cookie(sock->sk))
+ return 0;
+
+ p->cookie_value |= 0xF0;
+
+ return 0;
+}
+
int _version SEC("version") = 1;

char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_socket_cookie.c b/tools/testing/selftests/bpf/test_socket_cookie.c
index ca7ca87e91aa..0d955c65a4f8 100644
--- a/tools/testing/selftests/bpf/test_socket_cookie.c
+++ b/tools/testing/selftests/bpf/test_socket_cookie.c
@@ -133,6 +133,7 @@ static int run_test(int cgfd)
struct bpf_prog_load_attr attr;
struct bpf_program *prog;
struct bpf_object *pobj;
+ struct bpf_link *link;
const char *prog_name;
int server_fd = -1;
int client_fd = -1;
@@ -153,11 +154,18 @@ static int run_test(int cgfd)
bpf_object__for_each_program(prog, pobj) {
prog_name = bpf_program__section_name(prog);

- if (libbpf_attach_type_by_name(prog_name, &attach_type))
- goto err;
-
- err = bpf_prog_attach(bpf_program__fd(prog), cgfd, attach_type,
- BPF_F_ALLOW_OVERRIDE);
+ if (bpf_program__is_tracing(prog)) {
+ link = bpf_program__attach(prog);
+ err = !link;
+ continue;
+ } else {
+ if (libbpf_attach_type_by_name(prog_name, &attach_type))
+ goto err;
+
+ err = bpf_prog_attach(bpf_program__fd(prog), cgfd,
+ attach_type,
+ BPF_F_ALLOW_OVERRIDE);
+ }
if (err) {
log_err("Failed to attach prog %s", prog_name);
goto out;
--
2.29.2.454.gaff20da3a2-goog
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