bpf: Add bpf_skc_to_udp6_sock() helper

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

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c23998c..3d2ade7 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1653,6 +1653,7 @@ 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;
+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);

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b9412ab..0cb8ec9 100644 (file)
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3279,6 +3279,12 @@ 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),                     \
@@ -3420,7 +3426,8 @@ 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

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 48d935b..5d59dda 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1523,6 +1523,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
                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 ?

diff --git a/net/core/filter.c b/net/core/filter.c
index 0b4e5ae..c796e14 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -9369,3 +9369,25 @@ const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto = {
        .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],
+};

diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py
index d886657..6bab40f 100755 (executable)
--- 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',

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index b9412ab..0cb8ec9 100644 (file)
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3279,6 +3279,12 @@ 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),                     \
@@ -3420,7 +3426,8 @@ 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