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 316c4e271b36..4c4224e3e10a 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; }