diff mbox series

[bpf-next,2/2] selftests/bpf: Cover 4-byte load from remote_port in bpf_sk_lookup

Message ID 20220207131459.504292-3-jakub@cloudflare.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series Split bpf_sk_lookup remote_port field | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for bpf-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers warning 10 maintainers not CCed: joe@cilium.io linux-kselftest@vger.kernel.org kpsingh@kernel.org john.fastabend@gmail.com kafai@fb.com songliubraving@fb.com shuah@kernel.org lmb@cloudflare.com davemarchevsky@fb.com yhs@fb.com
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch fail ERROR: space prohibited before that ':' (ctx:WxV) WARNING: line length of 84 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-PR fail PR summary
bpf/vmtest-bpf-next fail VM_Test

Commit Message

Jakub Sitnicki Feb. 7, 2022, 1:14 p.m. UTC 
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>
---
 tools/include/uapi/linux/bpf.h                     | 3 ++-
 tools/testing/selftests/bpf/progs/test_sk_lookup.c | 6 ++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

Comments

Yonghong Song Feb. 7, 2022, 7:20 p.m. UTC | #1 
On 2/7/22 5:14 AM, Jakub Sitnicki wrote:
> 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>

Acked-by: Yonghong Song <yhs@fb.com>
diff mbox series

Patch

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index a7f0ddedac1f..afe3d0d7f5f2 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -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 */
diff --git a/tools/testing/selftests/bpf/progs/test_sk_lookup.c b/tools/testing/selftests/bpf/progs/test_sk_lookup.c
index 83b0aaa52ef7..bf5b7caefdd0 100644
--- a/tools/testing/selftests/bpf/progs/test_sk_lookup.c
+++ b/tools/testing/selftests/bpf/progs/test_sk_lookup.c
@@ -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) ||