Re: [PATCH 5/5] bpf: sockmap, sockhash: test looking up fds
From: Jakub Sitnicki <jakub@cloudflare.com>
Date: 2020-03-11 13:52:45
Also in:
bpf, linux-kselftest, lkml
On Tue, Mar 10, 2020 at 06:47 PM CET, Lorenz Bauer wrote:
quoted hunk ↗ jump to hunk
Make sure that looking up an element from the map succeeds, and that the fd is valid by using it an fcntl call. Signed-off-by: Lorenz Bauer <redacted> --- .../selftests/bpf/prog_tests/sockmap_listen.c | 26 ++++++++++++++----- 1 file changed, 20 insertions(+), 6 deletions(-)diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c index 52aa468bdccd..929e1e77ecc6 100644 --- a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c@@ -453,7 +453,7 @@ static void test_lookup_after_delete(int family, int sotype, int mapfd) xclose(s); } -static void test_lookup_32_bit_value(int family, int sotype, int mapfd) +static void test_lookup_fd(int family, int sotype, int mapfd) { u32 key, value32; int err, s;@@ -466,7 +466,7 @@ static void test_lookup_32_bit_value(int family, int sotype, int mapfd) sizeof(value32), 1, 0); if (mapfd < 0) { FAIL_ERRNO("map_create"); - goto close; + goto close_sock; } key = 0;@@ -475,11 +475,25 @@ static void test_lookup_32_bit_value(int family, int sotype, int mapfd) errno = 0; err = bpf_map_lookup_elem(mapfd, &key, &value32); - if (!err || errno != ENOSPC) - FAIL_ERRNO("map_lookup: expected ENOSPC"); + if (err) { + FAIL_ERRNO("map_lookup"); + goto close_map; + } + if ((int)value32 == s) { + FAIL("return value is identical"); + goto close; + } + + err = fcntl(value32, F_GETFD); + if (err == -1) + FAIL_ERRNO("fcntl");
I would call getsockopt()/getsockname() to assert that the FD lookup succeeded. We want to know not only that it's an FD (-EBADFD case), but also that it's associated with a socket (-ENOTSOCK). We can go even further, and compare socket cookies to ensure we got an FD for the expected socket. Also, I'm wondering if we could keep the -ENOSPC case test-covered by temporarily dropping NET_ADMIN capability.
quoted hunk ↗ jump to hunk
+ +close: + xclose(value32); +close_map: xclose(mapfd); -close: +close_sock: xclose(s); }@@ -1456,7 +1470,7 @@ static void test_ops(struct test_sockmap_listen *skel, struct bpf_map *map, /* lookup */ TEST(test_lookup_after_insert), TEST(test_lookup_after_delete), - TEST(test_lookup_32_bit_value), + TEST(test_lookup_fd), /* update */ TEST(test_update_existing), /* races with insert/delete */