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Subject[PATCH bpf-next v2 4/4] selftest: bpf: Test copying a sockmap and sockhash
Date
Since we can now call map_update_elem(sockmap) from bpf_iter context
it's possible to copy a sockmap or sockhash in the kernel. Add a
selftest which exercises this.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
---
.../selftests/bpf/prog_tests/sockmap_basic.c | 14 +++++-----
.../selftests/bpf/progs/bpf_iter_sockmap.c | 27 +++++++++++++++----
2 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
index e8a4bfb4d9f4..854a508e81ce 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
@@ -194,7 +194,7 @@ static void test_sockmap_invalid_update(void)
test_sockmap_invalid_update__destroy(skel);
}

-static void test_sockmap_iter(enum bpf_map_type map_type)
+static void test_sockmap_copy(enum bpf_map_type map_type)
{
DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);
int err, len, src_fd, iter_fd, duration = 0;
@@ -242,7 +242,7 @@ static void test_sockmap_iter(enum bpf_map_type map_type)
linfo.map.map_fd = src_fd;
opts.link_info = &linfo;
opts.link_info_len = sizeof(linfo);
- link = bpf_program__attach_iter(skel->progs.count_elems, &opts);
+ link = bpf_program__attach_iter(skel->progs.copy, &opts);
if (CHECK(IS_ERR(link), "attach_iter", "attach_iter failed\n"))
goto out;

@@ -265,6 +265,8 @@ static void test_sockmap_iter(enum bpf_map_type map_type)
skel->bss->socks, num_sockets))
goto close_iter;

+ compare_cookies(src, skel->maps.dst);
+
close_iter:
close(iter_fd);
free_link:
@@ -294,8 +296,8 @@ void test_sockmap_basic(void)
test_sockmap_update(BPF_MAP_TYPE_SOCKHASH);
if (test__start_subtest("sockmap update in unsafe context"))
test_sockmap_invalid_update();
- if (test__start_subtest("sockmap iter"))
- test_sockmap_iter(BPF_MAP_TYPE_SOCKMAP);
- if (test__start_subtest("sockhash iter"))
- test_sockmap_iter(BPF_MAP_TYPE_SOCKHASH);
+ if (test__start_subtest("sockmap copy"))
+ test_sockmap_copy(BPF_MAP_TYPE_SOCKMAP);
+ if (test__start_subtest("sockhash copy"))
+ test_sockmap_copy(BPF_MAP_TYPE_SOCKHASH);
}
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_sockmap.c b/tools/testing/selftests/bpf/progs/bpf_iter_sockmap.c
index 1af7555f6057..f3af0e30cead 100644
--- a/tools/testing/selftests/bpf/progs/bpf_iter_sockmap.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_sockmap.c
@@ -22,21 +22,38 @@ struct {
__type(value, __u64);
} sockhash SEC(".maps");

+struct {
+ __uint(type, BPF_MAP_TYPE_SOCKHASH);
+ __uint(max_entries, 64);
+ __type(key, __u32);
+ __type(value, __u64);
+} dst SEC(".maps");
+
__u32 elems = 0;
__u32 socks = 0;

SEC("iter/sockmap")
-int count_elems(struct bpf_iter__sockmap *ctx)
+int copy(struct bpf_iter__sockmap *ctx)
{
struct sock *sk = ctx->sk;
__u32 tmp, *key = ctx->key;
int ret;

- if (key)
- elems++;
+ if (!key)
+ return 0;

- if (sk)
+ elems++;
+
+ /* We need a temporary buffer on the stack, since the verifier doesn't
+ * let us use the pointer from the context as an argument to the helper.
+ */
+ tmp = *key;
+
+ if (sk) {
socks++;
+ return bpf_map_update_elem(&dst, &tmp, sk, 0) != 0;
+ }

- return 0;
+ ret = bpf_map_delete_elem(&dst, &tmp);
+ return ret && ret != -ENOENT;
}
--
2.25.1
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