bpf: Add bpf_skc_to_{tcp, tcp_timewait, tcp_request}_sock() helpers

Three more helpers are added to cast a sock_common pointer to
an tcp_sock, tcp_timewait_sock or a tcp_request_sock for
tracing programs.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200623230811.3988277-1-yhs@fb.com

Author: yonghong-song

include/linux/bpf.h

@@ -1650,6 +1650,9 @@ extern const struct bpf_func_proto bpf_ringbuf_submit_proto;
 extern const struct bpf_func_proto bpf_ringbuf_discard_proto;
 extern const struct bpf_func_proto bpf_ringbuf_query_proto;
 extern const struct bpf_func_proto bpf_skc_to_tcp6_sock_proto;
+extern const struct bpf_func_proto bpf_skc_to_tcp_sock_proto;
+extern const struct bpf_func_proto bpf_skc_to_tcp_timewait_sock_proto;
+extern const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto;
 
 const struct bpf_func_proto *bpf_tracing_func_proto(
 	enum bpf_func_id func_id, const struct bpf_prog *prog);

include/uapi/linux/bpf.h

@@ -3261,6 +3261,24 @@ union bpf_attr {
  *		Dynamically cast a *sk* pointer to a *tcp6_sock* pointer.
  *	Return
  *		*sk* if casting is valid, or NULL otherwise.
+ *
+ * struct tcp_sock *bpf_skc_to_tcp_sock(void *sk)
+ *	Description
+ *		Dynamically cast a *sk* pointer to a *tcp_sock* pointer.
+ *	Return
+ *		*sk* if casting is valid, or NULL otherwise.
+ *
+ * struct tcp_timewait_sock *bpf_skc_to_tcp_timewait_sock(void *sk)
+ * 	Description
+ *		Dynamically cast a *sk* pointer to a *tcp_timewait_sock* pointer.
+ *	Return
+ *		*sk* if casting is valid, or NULL otherwise.
+ *
+ * struct tcp_request_sock *bpf_skc_to_tcp_request_sock(void *sk)
+ * 	Description
+ *		Dynamically cast a *sk* pointer to a *tcp_request_sock* pointer.
+ *	Return
+ *		*sk* if casting is valid, or NULL otherwise.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -3399,7 +3417,10 @@ union bpf_attr {
 	FN(ringbuf_discard),		\
 	FN(ringbuf_query),		\
 	FN(csum_level),			\
-	FN(skc_to_tcp6_sock),
+	FN(skc_to_tcp6_sock),		\
+	FN(skc_to_tcp_sock),		\
+	FN(skc_to_tcp_timewait_sock),	\
+	FN(skc_to_tcp_request_sock),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call

kernel/trace/bpf_trace.c

@@ -1517,6 +1517,12 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_xdp_output_proto;
 	case BPF_FUNC_skc_to_tcp6_sock:
 		return &bpf_skc_to_tcp6_sock_proto;
+	case BPF_FUNC_skc_to_tcp_sock:
+		return &bpf_skc_to_tcp_sock_proto;
+	case BPF_FUNC_skc_to_tcp_timewait_sock:
+		return &bpf_skc_to_tcp_timewait_sock_proto;
+	case BPF_FUNC_skc_to_tcp_request_sock:
+		return &bpf_skc_to_tcp_request_sock_proto;
 #endif
 	case BPF_FUNC_seq_printf:
 		return prog->expected_attach_type == BPF_TRACE_ITER ?

net/core/filter.c

@@ -74,6 +74,7 @@
 #include <net/lwtunnel.h>
 #include <net/ipv6_stubs.h>
 #include <net/bpf_sk_storage.h>
+#include <net/transp_v6.h>
 
 /**
  *	sk_filter_trim_cap - run a packet through a socket filter
@@ -9307,3 +9308,64 @@ const struct bpf_func_proto bpf_skc_to_tcp6_sock_proto = {
 	.check_btf_id		= check_arg_btf_id,
 	.ret_btf_id		= &btf_sock_ids[BTF_SOCK_TYPE_TCP6],
 };
+
+BPF_CALL_1(bpf_skc_to_tcp_sock, struct sock *, sk)
+{
+	if (sk_fullsock(sk) && sk->sk_protocol == IPPROTO_TCP)
+		return (unsigned long)sk;
+
+	return (unsigned long)NULL;
+}
+
+const struct bpf_func_proto bpf_skc_to_tcp_sock_proto = {
+	.func			= bpf_skc_to_tcp_sock,
+	.gpl_only		= false,
+	.ret_type		= RET_PTR_TO_BTF_ID_OR_NULL,
+	.arg1_type		= ARG_PTR_TO_BTF_ID,
+	.check_btf_id		= check_arg_btf_id,
+	.ret_btf_id		= &btf_sock_ids[BTF_SOCK_TYPE_TCP],
+};
+
+BPF_CALL_1(bpf_skc_to_tcp_timewait_sock, struct sock *, sk)
+{
+	if (sk->sk_prot == &tcp_prot && sk->sk_state == TCP_TIME_WAIT)
+		return (unsigned long)sk;
+
+#if IS_BUILTIN(CONFIG_IPV6)
+	if (sk->sk_prot == &tcpv6_prot && sk->sk_state == TCP_TIME_WAIT)
+		return (unsigned long)sk;
+#endif
+
+	return (unsigned long)NULL;
+}
+
+const struct bpf_func_proto bpf_skc_to_tcp_timewait_sock_proto = {
+	.func			= bpf_skc_to_tcp_timewait_sock,
+	.gpl_only		= false,
+	.ret_type		= RET_PTR_TO_BTF_ID_OR_NULL,
+	.arg1_type		= ARG_PTR_TO_BTF_ID,
+	.check_btf_id		= check_arg_btf_id,
+	.ret_btf_id		= &btf_sock_ids[BTF_SOCK_TYPE_TCP_TW],
+};
+
+BPF_CALL_1(bpf_skc_to_tcp_request_sock, struct sock *, sk)
+{
+	if (sk->sk_prot == &tcp_prot  && sk->sk_state == TCP_NEW_SYN_RECV)
+		return (unsigned long)sk;
+
+#if IS_BUILTIN(CONFIG_IPV6)
+	if (sk->sk_prot == &tcpv6_prot && sk->sk_state == TCP_NEW_SYN_RECV)
+		return (unsigned long)sk;
+#endif
+
+	return (unsigned long)NULL;
+}
+
+const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto = {
+	.func			= bpf_skc_to_tcp_request_sock,
+	.gpl_only		= false,
+	.ret_type		= RET_PTR_TO_BTF_ID_OR_NULL,
+	.arg1_type		= ARG_PTR_TO_BTF_ID,
+	.check_btf_id		= check_arg_btf_id,
+	.ret_btf_id		= &btf_sock_ids[BTF_SOCK_TYPE_TCP_REQ],
+};

scripts/bpf_helpers_doc.py

@@ -422,6 +422,9 @@ class PrinterHelpers(Printer):
             'struct tcphdr',
             'struct seq_file',
             'struct tcp6_sock',
+            'struct tcp_sock',
+            'struct tcp_timewait_sock',
+            'struct tcp_request_sock',
 
             'struct __sk_buff',
             'struct sk_msg_md',
@@ -460,6 +463,9 @@ class PrinterHelpers(Printer):
             'struct tcphdr',
             'struct seq_file',
             'struct tcp6_sock',
+            'struct tcp_sock',
+            'struct tcp_timewait_sock',
+            'struct tcp_request_sock',
     }
     mapped_types = {
             'u8': '__u8',

tools/include/uapi/linux/bpf.h

@@ -3261,6 +3261,24 @@ union bpf_attr {
  *		Dynamically cast a *sk* pointer to a *tcp6_sock* pointer.
  *	Return
  *		*sk* if casting is valid, or NULL otherwise.
+ *
+ * struct tcp_sock *bpf_skc_to_tcp_sock(void *sk)
+ *	Description
+ *		Dynamically cast a *sk* pointer to a *tcp_sock* pointer.
+ *	Return
+ *		*sk* if casting is valid, or NULL otherwise.
+ *
+ * struct tcp_timewait_sock *bpf_skc_to_tcp_timewait_sock(void *sk)
+ * 	Description
+ *		Dynamically cast a *sk* pointer to a *tcp_timewait_sock* pointer.
+ *	Return
+ *		*sk* if casting is valid, or NULL otherwise.
+ *
+ * struct tcp_request_sock *bpf_skc_to_tcp_request_sock(void *sk)
+ * 	Description
+ *		Dynamically cast a *sk* pointer to a *tcp_request_sock* pointer.
+ *	Return
+ *		*sk* if casting is valid, or NULL otherwise.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -3399,7 +3417,10 @@ union bpf_attr {
 	FN(ringbuf_discard),		\
 	FN(ringbuf_query),		\
 	FN(csum_level),			\
-	FN(skc_to_tcp6_sock),
+	FN(skc_to_tcp6_sock),		\
+	FN(skc_to_tcp_sock),		\
+	FN(skc_to_tcp_timewait_sock),	\
+	FN(skc_to_tcp_request_sock),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call