[PATCH RFC bpf-next 2/3] bpf: Fix bpf_sk_lookup.remote_port on big-endian

[Ilya Leoshkevich <iii@linux.ibm.com>]

On big-endian, the port is available in the second __u16, not the first
one. Therefore, provide a big-endian-specific definition that reflects
that. Also, define remote_port_compat in order to have nicer
architecture-agnostic code in the verifier and in tests.

Fixes: 9a69e2b385f4 ("bpf: Make remote_port field in struct bpf_sk_lookup 16-bit wide")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 include/uapi/linux/bpf.h       | 17 +++++++++++++++--
 net/core/filter.c              |  5 ++---
 tools/include/uapi/linux/bpf.h | 17 +++++++++++++++--
 3 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index afe3d0d7f5f2..7b0e5efa58e0 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -10,6 +10,7 @@
 
 #include <linux/types.h>
 #include <linux/bpf_common.h>
+#include <asm/byteorder.h>
 
 /* Extended instruction set based on top of classic BPF */
 
@@ -6453,8 +6454,20 @@ 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 */
-	__be16 remote_port;	/* Network byte order */
-	__u16 :16;		/* Zero padding */
+	union {
+		struct {
+#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN)
+			__be16 remote_port;	/* Network byte order */
+			__u16 :16;		/* Zero padding */
+#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN)
+			__u16 :16;		/* Zero padding */
+			__be16 remote_port;	/* Network byte order */
+#else
+#error unspecified endianness
+#endif
+		};
+		__u32 remote_port_compat;
+	};
 	__u32 local_ip4;	/* Network byte order */
 	__u32 local_ip6[4];	/* Network byte order */
 	__u32 local_port;	/* Host byte order */
diff --git a/net/core/filter.c b/net/core/filter.c
index 65869fd510e8..4b247d5aebe8 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -10856,8 +10856,7 @@ static bool sk_lookup_is_valid_access(int off, int size,
 	case bpf_ctx_range(struct bpf_sk_lookup, local_ip4):
 	case bpf_ctx_range_till(struct bpf_sk_lookup, remote_ip6[0], remote_ip6[3]):
 	case bpf_ctx_range_till(struct bpf_sk_lookup, local_ip6[0], local_ip6[3]):
-	case offsetof(struct bpf_sk_lookup, remote_port) ...
-	     offsetof(struct bpf_sk_lookup, local_ip4) - 1:
+	case bpf_ctx_range(struct bpf_sk_lookup, remote_port_compat):
 	case bpf_ctx_range(struct bpf_sk_lookup, local_port):
 	case bpf_ctx_range(struct bpf_sk_lookup, ingress_ifindex):
 		bpf_ctx_record_field_size(info, sizeof(__u32));
@@ -10938,7 +10937,7 @@ static u32 sk_lookup_convert_ctx_access(enum bpf_access_type type,
 #endif
 		break;
 	}
-	case offsetof(struct bpf_sk_lookup, remote_port):
+	case offsetof(struct bpf_sk_lookup, remote_port_compat):
 		*insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->src_reg,
 				      bpf_target_off(struct bpf_sk_lookup_kern,
 						     sport, 2, target_size));
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index afe3d0d7f5f2..7b0e5efa58e0 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -10,6 +10,7 @@
 
 #include <linux/types.h>
 #include <linux/bpf_common.h>
+#include <asm/byteorder.h>
 
 /* Extended instruction set based on top of classic BPF */
 
@@ -6453,8 +6454,20 @@ 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 */
-	__be16 remote_port;	/* Network byte order */
-	__u16 :16;		/* Zero padding */
+	union {
+		struct {
+#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN)
+			__be16 remote_port;	/* Network byte order */
+			__u16 :16;		/* Zero padding */
+#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN)
+			__u16 :16;		/* Zero padding */
+			__be16 remote_port;	/* Network byte order */
+#else
+#error unspecified endianness
+#endif
+		};
+		__u32 remote_port_compat;
+	};
 	__u32 local_ip4;	/* Network byte order */
 	__u32 local_ip6[4];	/* Network byte order */
 	__u32 local_port;	/* Host byte order */
-- 
2.34.1