bpf: Add support for reading socket family, type, protocol
Add socket family, type and protocol to bpf_sock allowing bpf programs
read-only access.
Add __sk_flags_offset[0] to struct sock before the bitfield to
programmtically determine the offset of the unsigned int containing
protocol and type.
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sock.h b/include/net/sock.h
index 442cbb1..69afda6 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -389,6 +389,21 @@ struct sock {
* Because of non atomicity rules, all
* changes are protected by socket lock.
*/
+ unsigned int __sk_flags_offset[0];
+#ifdef __BIG_ENDIAN_BITFIELD
+#define SK_FL_PROTO_SHIFT 16
+#define SK_FL_PROTO_MASK 0x00ff0000
+
+#define SK_FL_TYPE_SHIFT 0
+#define SK_FL_TYPE_MASK 0x0000ffff
+#else
+#define SK_FL_PROTO_SHIFT 8
+#define SK_FL_PROTO_MASK 0x0000ff00
+
+#define SK_FL_TYPE_SHIFT 16
+#define SK_FL_TYPE_MASK 0xffff0000
+#endif
+
kmemcheck_bitfield_begin(flags);
unsigned int sk_padding : 2,
sk_no_check_tx : 1,
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index bfe5e31..6123d9b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -571,6 +571,9 @@ enum bpf_ret_code {
struct bpf_sock {
__u32 bound_dev_if;
+ __u32 family;
+ __u32 type;
+ __u32 protocol;
};
/* User return codes for XDP prog type.
diff --git a/net/core/filter.c b/net/core/filter.c
index 0ab252e..56b4358 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3121,6 +3121,27 @@ static u32 sock_filter_convert_ctx_access(enum bpf_access_type type,
*insn++ = BPF_LDX_MEM(BPF_W, dst_reg, src_reg,
offsetof(struct sock, sk_bound_dev_if));
break;
+
+ case offsetof(struct bpf_sock, family):
+ BUILD_BUG_ON(FIELD_SIZEOF(struct sock, sk_family) != 2);
+
+ *insn++ = BPF_LDX_MEM(BPF_H, dst_reg, src_reg,
+ offsetof(struct sock, sk_family));
+ break;
+
+ case offsetof(struct bpf_sock, type):
+ *insn++ = BPF_LDX_MEM(BPF_W, dst_reg, src_reg,
+ offsetof(struct sock, __sk_flags_offset));
+ *insn++ = BPF_ALU32_IMM(BPF_AND, dst_reg, SK_FL_TYPE_MASK);
+ *insn++ = BPF_ALU32_IMM(BPF_RSH, dst_reg, SK_FL_TYPE_SHIFT);
+ break;
+
+ case offsetof(struct bpf_sock, protocol):
+ *insn++ = BPF_LDX_MEM(BPF_W, dst_reg, src_reg,
+ offsetof(struct sock, __sk_flags_offset));
+ *insn++ = BPF_ALU32_IMM(BPF_AND, dst_reg, SK_FL_PROTO_MASK);
+ *insn++ = BPF_ALU32_IMM(BPF_RSH, dst_reg, SK_FL_PROTO_SHIFT);
+ break;
}
return insn - insn_buf;