diff options
| author | Jakub Sitnicki <jakub@cloudflare.com> | 2022-03-19 19:33:56 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-03-20 18:59:00 -0700 |
| commit | ce5236800116d18ac2c06c58f73930406e3ea4be (patch) | |
| tree | a68caed04866465d23d56a0ce32220741231745a /tools/testing/selftests/bpf/progs | |
| parent | 3c69611b8926f8e74fcf76bd97ae0e5dafbeb26a (diff) | |
selftests/bpf: Fix test for 4-byte load from remote_port on big-endian
The context access converter rewrites the 4-byte load from
bpf_sk_lookup->remote_port to a 2-byte load from bpf_sk_lookup_kern
structure.
It means that we cannot treat the destination register contents as a 32-bit
value, or the code will not be portable across big- and little-endian
architectures.
This is exactly the same case as with 4-byte loads from bpf_sock->dst_port
so follow the approach outlined in [1] and treat the register contents as a
16-bit value in the test.
[1]: https://lore.kernel.org/bpf/20220317113920.1068535-5-jakub@cloudflare.com/
Fixes: 2ed0dc5937d3 ("selftests/bpf: Cover 4-byte load from remote_port in bpf_sk_lookup")
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220319183356.233666-4-jakub@cloudflare.com
Diffstat (limited to 'tools/testing/selftests/bpf/progs')
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_sk_lookup.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/tools/testing/selftests/bpf/progs/test_sk_lookup.c b/tools/testing/selftests/bpf/progs/test_sk_lookup.c index 38b7a1fe67b6..6058dcb11b36 100644 --- a/tools/testing/selftests/bpf/progs/test_sk_lookup.c +++ b/tools/testing/selftests/bpf/progs/test_sk_lookup.c @@ -418,9 +418,15 @@ int ctx_narrow_access(struct bpf_sk_lookup *ctx) if (LSW(ctx->remote_port, 0) != SRC_PORT) return SK_DROP; - /* Load from remote_port field with zero padding (backward compatibility) */ + /* + * NOTE: 4-byte load from bpf_sk_lookup at remote_port offset + * is quirky. It gets rewritten by the access converter to a + * 2-byte load for backward compatibility. Treating the load + * result as a be16 value makes the code portable across + * little- and big-endian platforms. + */ val_u32 = *(__u32 *)&ctx->remote_port; - if (val_u32 != bpf_htonl(bpf_ntohs(SRC_PORT) << 16)) + if (val_u32 != SRC_PORT) return SK_DROP; /* Narrow loads from local_port field. Expect DST_PORT. */ |