Commit 2ed0dc59 authored by Jakub Sitnicki's avatar Jakub Sitnicki Committed by Alexei Starovoitov
Browse files

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



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: default avatarJakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220209184333.654927-3-jakub@cloudflare.com
parent 9a69e2b3

tools/include/uapi/linux/bpf.h

+2 −1
Original line number Diff line number Diff line
@@ -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 */

tools/testing/selftests/bpf/progs/test_sk_lookup.c

+6 −0
Original line number Diff line number Diff line
@@ -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) ||