bpf: Add state, dst_ip4, dst_ip6 and dst_port to bpf_sock

This patch adds "state", "dst_ip4", "dst_ip6" and "dst_port" to the
bpf_sock.  The userspace has already been using "state",
e.g. inet_diag (ss -t) and getsockopt(TCP_INFO).

This patch also allows narrow load on the following existing fields:
"family", "type", "protocol" and "src_port".  Unlike IP address,
the load offset is resticted to the first byte for them but it
can be relaxed later if there is a use case.

This patch also folds __sock_filter_check_size() into
bpf_sock_is_valid_access() since it is not called
by any where else.  All bpf_sock checking is in
one place.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

include/uapi/linux/bpf.h

@@ -2606,15 +2606,14 @@ struct bpf_sock {
 	__u32 protocol;
 	__u32 mark;
 	__u32 priority;
-	__u32 src_ip4;		/* Allows 1,2,4-byte read.
-				 * Stored in network byte order.
-				 */
-	__u32 src_ip6[4];	/* Allows 1,2,4-byte read.
-				 * Stored in network byte order.
-				 */
-	__u32 src_port;		/* Allows 4-byte read.
-				 * Stored in host byte order
-				 */
+	/* IP address also allows 1 and 2 bytes access */
+	__u32 src_ip4;
+	__u32 src_ip6[4];
+	__u32 src_port;		/* host byte order */
+	__u32 dst_port;		/* network byte order */
+	__u32 dst_ip4;
+	__u32 dst_ip6[4];
+	__u32 state;
 };
 
 struct bpf_sock_tuple {

net/core/filter.c

@@ -5958,21 +5958,6 @@ static bool __sock_filter_check_attach_type(int off,
 	return true;
 }
 
-static bool __sock_filter_check_size(int off, int size,
-				     struct bpf_insn_access_aux *info)
-{
-	const int size_default = sizeof(__u32);
-
-	switch (off) {
-	case bpf_ctx_range(struct bpf_sock, src_ip4):
-	case bpf_ctx_range_till(struct bpf_sock, src_ip6[0], src_ip6[3]):
-		bpf_ctx_record_field_size(info, size_default);
-		return bpf_ctx_narrow_access_ok(off, size, size_default);
-	}
-
-	return size == size_default;
-}
-
 bool bpf_sock_common_is_valid_access(int off, int size,
 				     enum bpf_access_type type,
 				     struct bpf_insn_access_aux *info)
@@ -5988,13 +5973,29 @@ bool bpf_sock_common_is_valid_access(int off, int size,
 bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type,
 			      struct bpf_insn_access_aux *info)
 {
+	const int size_default = sizeof(__u32);
+
 	if (off < 0 || off >= sizeof(struct bpf_sock))
 		return false;
 	if (off % size != 0)
 		return false;
-	if (!__sock_filter_check_size(off, size, info))
-		return false;
-	return true;
+
+	switch (off) {
+	case offsetof(struct bpf_sock, state):
+	case offsetof(struct bpf_sock, family):
+	case offsetof(struct bpf_sock, type):
+	case offsetof(struct bpf_sock, protocol):
+	case offsetof(struct bpf_sock, dst_port):
+	case offsetof(struct bpf_sock, src_port):
+	case bpf_ctx_range(struct bpf_sock, src_ip4):
+	case bpf_ctx_range_till(struct bpf_sock, src_ip6[0], src_ip6[3]):
+	case bpf_ctx_range(struct bpf_sock, dst_ip4):
+	case bpf_ctx_range_till(struct bpf_sock, dst_ip6[0], dst_ip6[3]):
+		bpf_ctx_record_field_size(info, size_default);
+		return bpf_ctx_narrow_access_ok(off, size, size_default);
+	}
+
+	return size == size_default;
 }
 
 static bool sock_filter_is_valid_access(int off, int size,
@@ -6838,24 +6839,32 @@ u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
 		break;
 
 	case offsetof(struct bpf_sock, family):
-		BUILD_BUG_ON(FIELD_SIZEOF(struct sock, sk_family) != 2);
-
-		*insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->src_reg,
-				      offsetof(struct sock, sk_family));
+		*insn++ = BPF_LDX_MEM(
+			BPF_FIELD_SIZEOF(struct sock_common, skc_family),
+			si->dst_reg, si->src_reg,
+			bpf_target_off(struct sock_common,
+				       skc_family,
+				       FIELD_SIZEOF(struct sock_common,
+						    skc_family),
+				       target_size));
 		break;
 
 	case offsetof(struct bpf_sock, type):
+		BUILD_BUG_ON(HWEIGHT32(SK_FL_TYPE_MASK) != BITS_PER_BYTE * 2);
 		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg,
 				      offsetof(struct sock, __sk_flags_offset));
 		*insn++ = BPF_ALU32_IMM(BPF_AND, si->dst_reg, SK_FL_TYPE_MASK);
 		*insn++ = BPF_ALU32_IMM(BPF_RSH, si->dst_reg, SK_FL_TYPE_SHIFT);
+		*target_size = 2;
 		break;
 
 	case offsetof(struct bpf_sock, protocol):
+		BUILD_BUG_ON(HWEIGHT32(SK_FL_PROTO_MASK) != BITS_PER_BYTE);
 		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg,
 				      offsetof(struct sock, __sk_flags_offset));
 		*insn++ = BPF_ALU32_IMM(BPF_AND, si->dst_reg, SK_FL_PROTO_MASK);
 		*insn++ = BPF_ALU32_IMM(BPF_RSH, si->dst_reg, SK_FL_PROTO_SHIFT);
+		*target_size = 1;
 		break;
 
 	case offsetof(struct bpf_sock, src_ip4):
@@ -6867,6 +6876,15 @@ u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
 				       target_size));
 		break;
 
+	case offsetof(struct bpf_sock, dst_ip4):
+		*insn++ = BPF_LDX_MEM(
+			BPF_SIZE(si->code), si->dst_reg, si->src_reg,
+			bpf_target_off(struct sock_common, skc_daddr,
+				       FIELD_SIZEOF(struct sock_common,
+						    skc_daddr),
+				       target_size));
+		break;
+
 	case bpf_ctx_range_till(struct bpf_sock, src_ip6[0], src_ip6[3]):
 #if IS_ENABLED(CONFIG_IPV6)
 		off = si->off;
@@ -6885,6 +6903,23 @@ u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
 #endif
 		break;
 
+	case bpf_ctx_range_till(struct bpf_sock, dst_ip6[0], dst_ip6[3]):
+#if IS_ENABLED(CONFIG_IPV6)
+		off = si->off;
+		off -= offsetof(struct bpf_sock, dst_ip6[0]);
+		*insn++ = BPF_LDX_MEM(
+			BPF_SIZE(si->code), si->dst_reg, si->src_reg,
+			bpf_target_off(struct sock_common,
+				       skc_v6_daddr.s6_addr32[0],
+				       FIELD_SIZEOF(struct sock_common,
+						    skc_v6_daddr.s6_addr32[0]),
+				       target_size) + off);
+#else
+		*insn++ = BPF_MOV32_IMM(si->dst_reg, 0);
+		*target_size = 4;
+#endif
+		break;
+
 	case offsetof(struct bpf_sock, src_port):
 		*insn++ = BPF_LDX_MEM(
 			BPF_FIELD_SIZEOF(struct sock_common, skc_num),
@@ -6894,6 +6929,26 @@ u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
 						    skc_num),
 				       target_size));
 		break;
+
+	case offsetof(struct bpf_sock, dst_port):
+		*insn++ = BPF_LDX_MEM(
+			BPF_FIELD_SIZEOF(struct sock_common, skc_dport),
+			si->dst_reg, si->src_reg,
+			bpf_target_off(struct sock_common, skc_dport,
+				       FIELD_SIZEOF(struct sock_common,
+						    skc_dport),
+				       target_size));
+		break;
+
+	case offsetof(struct bpf_sock, state):
+		*insn++ = BPF_LDX_MEM(
+			BPF_FIELD_SIZEOF(struct sock_common, skc_state),
+			si->dst_reg, si->src_reg,
+			bpf_target_off(struct sock_common, skc_state,
+				       FIELD_SIZEOF(struct sock_common,
+						    skc_state),
+				       target_size));
+		break;
 	}
 
 	return insn - insn_buf;