From: Yonghong Song <yhs@fb.com>
Date: Tue, 23 Jun 2020 16:08:15 -0700
Subject: bpf: Add bpf_skc_to_udp6_sock() helper
Patch-mainline: v5.9-rc1
Git-commit: 0d4fad3e57df2bf61e8ffc8d12a34b1caf9b8835
References: bsc#1177028

The helper is used in tracing programs to cast a socket
pointer to a udp6_sock pointer.
The return value could be NULL if the casting is illegal.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/bpf/20200623230815.3988481-1-yhs@fb.com
Acked-by: Gary Lin <glin@suse.com>
---
 include/linux/bpf.h            |    1 +
 include/uapi/linux/bpf.h       |    9 ++++++++-
 kernel/trace/bpf_trace.c       |    2 ++
 net/core/filter.c              |   22 ++++++++++++++++++++++
 scripts/bpf_helpers_doc.py     |    2 ++
 tools/include/uapi/linux/bpf.h |    9 ++++++++-
 6 files changed, 43 insertions(+), 2 deletions(-)

--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1662,6 +1662,7 @@ extern const struct bpf_func_proto bpf_s
 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;
+extern const struct bpf_func_proto bpf_skc_to_udp6_sock_proto;
 
 const struct bpf_func_proto *bpf_tracing_func_proto(
 	enum bpf_func_id func_id, const struct bpf_prog *prog);
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3277,6 +3277,12 @@ union bpf_attr {
  *		Dynamically cast a *sk* pointer to a *tcp_request_sock* pointer.
  *	Return
  *		*sk* if casting is valid, or NULL otherwise.
+ *
+ * struct udp6_sock *bpf_skc_to_udp6_sock(void *sk)
+ * 	Description
+ *		Dynamically cast a *sk* pointer to a *udp6_sock* pointer.
+ *	Return
+ *		*sk* if casting is valid, or NULL otherwise.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -3418,7 +3424,8 @@ union bpf_attr {
 	FN(skc_to_tcp6_sock),		\
 	FN(skc_to_tcp_sock),		\
 	FN(skc_to_tcp_timewait_sock),	\
-	FN(skc_to_tcp_request_sock),
+	FN(skc_to_tcp_request_sock),	\
+	FN(skc_to_udp6_sock),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1484,6 +1484,8 @@ tracing_prog_func_proto(enum bpf_func_id
 		return &bpf_skc_to_tcp_timewait_sock_proto;
 	case BPF_FUNC_skc_to_tcp_request_sock:
 		return &bpf_skc_to_tcp_request_sock_proto;
+	case BPF_FUNC_skc_to_udp6_sock:
+		return &bpf_skc_to_udp6_sock_proto;
 #endif
 	case BPF_FUNC_seq_printf:
 		return prog->expected_attach_type == BPF_TRACE_ITER ?
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -9353,3 +9353,25 @@ const struct bpf_func_proto bpf_skc_to_t
 	.check_btf_id		= check_arg_btf_id,
 	.ret_btf_id		= &btf_sock_ids[BTF_SOCK_TYPE_TCP_REQ],
 };
+
+BPF_CALL_1(bpf_skc_to_udp6_sock, struct sock *, sk)
+{
+	/* udp6_sock type is not generated in dwarf and hence btf,
+	 * trigger an explicit type generation here.
+	 */
+	BTF_TYPE_EMIT(struct udp6_sock);
+	if (sk_fullsock(sk) && sk->sk_protocol == IPPROTO_UDP &&
+	    sk->sk_type == SOCK_DGRAM && sk->sk_family == AF_INET6)
+		return (unsigned long)sk;
+
+	return (unsigned long)NULL;
+}
+
+const struct bpf_func_proto bpf_skc_to_udp6_sock_proto = {
+	.func			= bpf_skc_to_udp6_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_UDP6],
+};
--- a/scripts/bpf_helpers_doc.py
+++ b/scripts/bpf_helpers_doc.py
@@ -425,6 +425,7 @@ class PrinterHelpers(Printer):
             'struct tcp_sock',
             'struct tcp_timewait_sock',
             'struct tcp_request_sock',
+            'struct udp6_sock',
 
             'struct __sk_buff',
             'struct sk_msg_md',
@@ -466,6 +467,7 @@ class PrinterHelpers(Printer):
             'struct tcp_sock',
             'struct tcp_timewait_sock',
             'struct tcp_request_sock',
+            'struct udp6_sock',
     }
     mapped_types = {
             'u8': '__u8',
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3277,6 +3277,12 @@ union bpf_attr {
  *		Dynamically cast a *sk* pointer to a *tcp_request_sock* pointer.
  *	Return
  *		*sk* if casting is valid, or NULL otherwise.
+ *
+ * struct udp6_sock *bpf_skc_to_udp6_sock(void *sk)
+ * 	Description
+ *		Dynamically cast a *sk* pointer to a *udp6_sock* pointer.
+ *	Return
+ *		*sk* if casting is valid, or NULL otherwise.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -3418,7 +3424,8 @@ union bpf_attr {
 	FN(skc_to_tcp6_sock),		\
 	FN(skc_to_tcp_sock),		\
 	FN(skc_to_tcp_timewait_sock),	\
-	FN(skc_to_tcp_request_sock),
+	FN(skc_to_tcp_request_sock),	\
+	FN(skc_to_udp6_sock),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call