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selftests/bpf: Cover 4-byte load from remote_port in bpf_sk_lookup

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Extend the context access tests for sk_lookup prog to cover the surprising
case of a 4-byte load from the remote_port field, where the expected value
is actually shifted by 16 bits.

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220209184333.654927-3-jakub@cloudflare.com
This commit is contained in:
Jakub Sitnicki 2022-02-09 19:43:33 +01:00 committed by Alexei Starovoitov
parent 9a69e2b385
commit 2ed0dc5937
2 changed files with 8 additions and 1 deletions
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3
tools/include/uapi/linux/bpf.h
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@ -6453,7 +6453,8 @@ struct bpf_sk_lookup {
__u32 protocol; /* IP protocol (IPPROTO_TCP, IPPROTO_UDP) */
__u32 remote_ip4; /* Network byte order */
__u32 remote_ip6[4]; /* Network byte order */
__u32 remote_port; /* Network byte order */
__be16 remote_port; /* Network byte order */
__u16 :16; /* Zero padding */
__u32 local_ip4; /* Network byte order */
__u32 local_ip6[4]; /* Network byte order */
__u32 local_port; /* Host byte order */

6
tools/testing/selftests/bpf/progs/test_sk_lookup.c
View file

@ -392,6 +392,7 @@ int ctx_narrow_access(struct bpf_sk_lookup *ctx)
{
struct bpf_sock *sk;
int err, family;
__u32 val_u32;
bool v4;
v4 = (ctx->family == AF_INET);
@ -418,6 +419,11 @@ 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) */
val_u32 = *(__u32 *)&ctx->remote_port;
if (val_u32 != bpf_htonl(bpf_ntohs(SRC_PORT) << 16))
return SK_DROP;
/* Narrow loads from local_port field. Expect DST_PORT. */
if (LSB(ctx->local_port, 0) != ((DST_PORT >> 0) & 0xff) ||
LSB(ctx->local_port, 1) != ((DST_PORT >> 8) & 0xff) ||