netdev - [PATCH v2 bpf-next 1/4] bpf: Support bpf_get_socket

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Date:   Mon, 30 Jul 2018 17:42:28 -0700
From:   Andrey Ignatov <rdna@...com>
To:     <netdev@...r.kernel.org>
CC:     Andrey Ignatov <rdna@...com>, <ast@...nel.org>,
        <daniel@...earbox.net>, <yhs@...com>, <brakmo@...com>,
        <kernel-team@...com>
Subject: [PATCH v2 bpf-next 1/4] bpf: Support bpf_get_socket_cookie in more prog types

bpf_get_socket_cookie() helper can be used to identify skb that
correspond to the same socket.

Though socket cookie can be useful in many other use-cases where socket is
available in program context. Specifically BPF_PROG_TYPE_CGROUP_SOCK_ADDR
and BPF_PROG_TYPE_SOCK_OPS programs can benefit from it so that one of
them can augment a value in a map prepared earlier by other program for
the same socket.

The patch adds support to call bpf_get_socket_cookie() from
BPF_PROG_TYPE_CGROUP_SOCK_ADDR and BPF_PROG_TYPE_SOCK_OPS.

It doesn't introduce new helpers. Instead it reuses same helper name
bpf_get_socket_cookie() but adds support to this helper to accept
`struct bpf_sock_addr` and `struct bpf_sock_ops`.

Documentation in bpf.h is changed in a way that should not break
automatic generation of markdown.

Signed-off-by: Andrey Ignatov <rdna@...com>
Acked-by: Yonghong Song <yhs@...com>
---
 include/uapi/linux/bpf.h | 14 ++++++++++++++
 net/core/filter.c        | 28 ++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 870113916cac..0ebaaf7f3568 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1371,6 +1371,20 @@ union bpf_attr {
  * 		A 8-byte long non-decreasing number on success, or 0 if the
  * 		socket field is missing inside *skb*.
  *
+ * u64 bpf_get_socket_cookie(struct bpf_sock_addr *ctx)
+ * 	Description
+ * 		Equivalent to bpf_get_socket_cookie() helper that accepts
+ * 		*skb*, but gets socket from **struct bpf_sock_addr** contex.
+ * 	Return
+ * 		A 8-byte long non-decreasing number.
+ *
+ * u64 bpf_get_socket_cookie(struct bpf_sock_ops *ctx)
+ * 	Description
+ * 		Equivalent to bpf_get_socket_cookie() helper that accepts
+ * 		*skb*, but gets socket from **struct bpf_sock_ops** contex.
+ * 	Return
+ * 		A 8-byte long non-decreasing number.
+ *
  * u32 bpf_get_socket_uid(struct sk_buff *skb)
  * 	Return
  * 		The owner UID of the socket associated to *skb*. If the socket
diff --git a/net/core/filter.c b/net/core/filter.c
index 104d560946da..0b3c59468282 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3812,6 +3812,30 @@ static const struct bpf_func_proto bpf_get_socket_cookie_proto = {
 	.arg1_type      = ARG_PTR_TO_CTX,
 };
 
+BPF_CALL_1(bpf_get_socket_cookie_sock_addr, struct bpf_sock_addr_kern *, ctx)
+{
+	return sock_gen_cookie(ctx->sk);
+}
+
+static const struct bpf_func_proto bpf_get_socket_cookie_sock_addr_proto = {
+	.func		= bpf_get_socket_cookie_sock_addr,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+};
+
+BPF_CALL_1(bpf_get_socket_cookie_sock_ops, struct bpf_sock_ops_kern *, ctx)
+{
+	return sock_gen_cookie(ctx->sk);
+}
+
+static const struct bpf_func_proto bpf_get_socket_cookie_sock_ops_proto = {
+	.func		= bpf_get_socket_cookie_sock_ops,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+};
+
 BPF_CALL_1(bpf_get_socket_uid, struct sk_buff *, skb)
 {
 	struct sock *sk = sk_to_full_sk(skb->sk);
@@ -4788,6 +4812,8 @@ sock_addr_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		default:
 			return NULL;
 		}
+	case BPF_FUNC_get_socket_cookie:
+		return &bpf_get_socket_cookie_sock_addr_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
@@ -4930,6 +4956,8 @@ sock_ops_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sock_map_update_proto;
 	case BPF_FUNC_sock_hash_update:
 		return &bpf_sock_hash_update_proto;
+	case BPF_FUNC_get_socket_cookie:
+		return &bpf_get_socket_cookie_sock_ops_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
-- 
2.17.1