selftests/bpf: Add write tests for sk local storage map iterator

Add test to validate the overwrite of sock local storage map value in
map iterator and another one to ensure out-of-bound value writing is
rejected.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220810080538.1845898-9-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
index b690c9e..1571a65 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
@@ -1076,7 +1076,7 @@ static void test_bpf_sk_stoarge_map_iter_fd(void)
        if (!ASSERT_OK_PTR(skel, "bpf_iter_bpf_sk_storage_map__open_and_load"))
                return;
 
-       do_read_map_iter_fd(&skel->skeleton, skel->progs.dump_bpf_sk_storage_map,
+       do_read_map_iter_fd(&skel->skeleton, skel->progs.rw_bpf_sk_storage_map,
                            skel->maps.sk_stg_map);
 
        bpf_iter_bpf_sk_storage_map__destroy(skel);
@@ -1117,7 +1117,15 @@ static void test_bpf_sk_storage_map(void)
        linfo.map.map_fd = map_fd;
        opts.link_info = &linfo;
        opts.link_info_len = sizeof(linfo);
-       link = bpf_program__attach_iter(skel->progs.dump_bpf_sk_storage_map, &opts);
+       link = bpf_program__attach_iter(skel->progs.oob_write_bpf_sk_storage_map, &opts);
+       err = libbpf_get_error(link);
+       if (!ASSERT_EQ(err, -EACCES, "attach_oob_write_iter")) {
+               if (!err)
+                       bpf_link__destroy(link);
+               goto out;
+       }
+
+       link = bpf_program__attach_iter(skel->progs.rw_bpf_sk_storage_map, &opts);
        if (!ASSERT_OK_PTR(link, "attach_iter"))
                goto out;
 
@@ -1125,6 +1133,7 @@ static void test_bpf_sk_storage_map(void)
        if (!ASSERT_GE(iter_fd, 0, "create_iter"))
                goto free_link;
 
+       skel->bss->to_add_val = time(NULL);
        /* do some tests */
        while ((len = read(iter_fd, buf, sizeof(buf))) > 0)
                ;
@@ -1138,6 +1147,13 @@ static void test_bpf_sk_storage_map(void)
        if (!ASSERT_EQ(skel->bss->val_sum, expected_val, "val_sum"))
                goto close_iter;
 
+       for (i = 0; i < num_sockets; i++) {
+               err = bpf_map_lookup_elem(map_fd, &sock_fd[i], &val);
+               if (!ASSERT_OK(err, "map_lookup") ||
+                   !ASSERT_EQ(val, i + 1 + skel->bss->to_add_val, "check_map_value"))
+                       break;
+       }
+
 close_iter:
        close(iter_fd);
 free_link:

diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_sk_storage_map.c b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_sk_storage_map.c
index 6b70cca..c7b8e00 100644 (file)
--- a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_sk_storage_map.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_sk_storage_map.c
@@ -16,19 +16,37 @@ struct {
 
 __u32 val_sum = 0;
 __u32 ipv6_sk_count = 0;
+__u32 to_add_val = 0;
 
 SEC("iter/bpf_sk_storage_map")
-int dump_bpf_sk_storage_map(struct bpf_iter__bpf_sk_storage_map *ctx)
+int rw_bpf_sk_storage_map(struct bpf_iter__bpf_sk_storage_map *ctx)
 {
        struct sock *sk = ctx->sk;
        __u32 *val = ctx->value;
 
-       if (sk == (void *)0 || val == (void *)0)
+       if (sk == NULL || val == NULL)
                return 0;
 
        if (sk->sk_family == AF_INET6)
                ipv6_sk_count++;
 
        val_sum += *val;
+
+       *val += to_add_val;
+
+       return 0;
+}
+
+SEC("iter/bpf_sk_storage_map")
+int oob_write_bpf_sk_storage_map(struct bpf_iter__bpf_sk_storage_map *ctx)
+{
+       struct sock *sk = ctx->sk;
+       __u32 *val = ctx->value;
+
+       if (sk == NULL || val == NULL)
+               return 0;
+
+       *(val + 1) = 0xdeadbeef;
+
        return 0;
 }