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Date:   Thu, 14 Mar 2019 11:39:49 +0000
From:   Lorenz Bauer <lmb@...udflare.com>
To:     ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     kafai@...com, theojulienne@...hub.com,
        Lorenz Bauer <lmb@...udflare.com>
Subject: [PATCH v2 3/8] bpf: add skc_lookup_tcp helper

Allow looking up a sock_common. This gives eBPF programs
access to timewait and request sockets.

Signed-off-by: Lorenz Bauer <lmb@...udflare.com>
---
 include/uapi/linux/bpf.h |  20 ++++++-
 kernel/bpf/verifier.c    |   3 +-
 net/core/filter.c        | 113 +++++++++++++++++++++++++++++++++++----
 3 files changed, 124 insertions(+), 12 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 983b25cb608d..8e4f8276942a 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -2374,6 +2374,23 @@ union bpf_attr {
  *	Return
  *		A **struct bpf_sock** pointer on success, or NULL in
  *		case of failure.
+ *
+ * struct bpf_sock *bpf_skc_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
+ *	Description
+ *		Look for TCP socket matching *tuple*, optionally in a child
+ *		network namespace *netns*. The return value must be checked,
+ *		and if non-**NULL**, released via **bpf_sk_release**\ ().
+ *
+ *		This function is identical to bpf_sk_lookup_tcp, except that it
+ *		also returns timewait or request sockets. Use bpf_sk_fullsock
+ *		or bpf_tcp_socket to access the full structure.
+ *
+ *		This helper is available only if the kernel was compiled with
+ *		**CONFIG_NET** configuration option.
+ *	Return
+ *		Pointer to **struct bpf_sock**, or **NULL** in case of failure.
+ *		For sockets with reuseport option, the **struct bpf_sock**
+ *		result is from **reuse->socks**\ [] using the hash of the tuple.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -2474,7 +2491,8 @@ union bpf_attr {
 	FN(sk_fullsock),		\
 	FN(tcp_sock),			\
 	FN(skb_ecn_set_ce),		\
-	FN(get_listener_sock),
+	FN(get_listener_sock),		\
+	FN(skc_lookup_tcp),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f60d9df4e00a..94420942af32 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -369,7 +369,8 @@ static bool is_release_function(enum bpf_func_id func_id)
 static bool is_acquire_function(enum bpf_func_id func_id)
 {
 	return func_id == BPF_FUNC_sk_lookup_tcp ||
-		func_id == BPF_FUNC_sk_lookup_udp;
+		func_id == BPF_FUNC_sk_lookup_udp ||
+		func_id == BPF_FUNC_skc_lookup_tcp;
 }
 
 static bool is_ptr_cast_function(enum bpf_func_id func_id)
diff --git a/net/core/filter.c b/net/core/filter.c
index f879791ea53f..f5210773cfd8 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5156,15 +5156,15 @@ static struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple,
 	return sk;
 }
 
-/* bpf_sk_lookup performs the core lookup for different types of sockets,
+/* bpf_skc_lookup performs the core lookup for different types of sockets,
  * taking a reference on the socket if it doesn't have the flag SOCK_RCU_FREE.
  * Returns the socket as an 'unsigned long' to simplify the casting in the
  * callers to satisfy BPF_CALL declarations.
  */
 static unsigned long
-__bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
-		struct net *caller_net, u32 ifindex, u8 proto, u64 netns_id,
-		u64 flags)
+__bpf_skc_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
+		 struct net *caller_net, u32 ifindex, u8 proto, u64 netns_id,
+		 u64 flags)
 {
 	struct sock *sk = NULL;
 	u8 family = AF_UNSPEC;
@@ -5192,15 +5192,28 @@ __bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
 		put_net(net);
 	}
 
-	if (sk)
-		sk = sk_to_full_sk(sk);
 out:
 	return (unsigned long) sk;
 }
 
 static unsigned long
-bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
-	      u8 proto, u64 netns_id, u64 flags)
+__bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
+		struct net *caller_net, u32 ifindex, u8 proto, u64 netns_id,
+		u64 flags)
+{
+	struct sock *sk;
+
+	sk = (struct sock *)__bpf_skc_lookup(skb, tuple, len, caller_net,
+					    ifindex, proto, netns_id, flags);
+	if (sk)
+		sk = sk_to_full_sk(sk);
+
+	return (unsigned long)sk;
+}
+
+static unsigned long
+bpf_skc_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
+	       u8 proto, u64 netns_id, u64 flags)
 {
 	struct net *caller_net;
 	int ifindex;
@@ -5213,10 +5226,42 @@ bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
 		ifindex = 0;
 	}
 
-	return __bpf_sk_lookup(skb, tuple, len, caller_net, ifindex,
-			      proto, netns_id, flags);
+	return __bpf_skc_lookup(skb, tuple, len, caller_net, ifindex,
+				proto, netns_id, flags);
 }
 
+static unsigned long
+bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
+	      u8 proto, u64 netns_id, u64 flags)
+{
+	struct sock *sk;
+
+	sk = (struct sock *)bpf_skc_lookup(skb, tuple, len, proto, netns_id,
+					  flags);
+	if (sk)
+		sk = sk_to_full_sk(sk);
+
+	return (unsigned long)sk;
+}
+
+BPF_CALL_5(bpf_skc_lookup_tcp, struct sk_buff *, skb,
+	   struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)
+{
+	return bpf_skc_lookup(skb, tuple, len, IPPROTO_TCP, netns_id, flags);
+}
+
+static const struct bpf_func_proto bpf_skc_lookup_tcp_proto = {
+	.func		= bpf_skc_lookup_tcp,
+	.gpl_only	= false,
+	.pkt_access	= true,
+	.ret_type	= RET_PTR_TO_SOCK_COMMON_OR_NULL,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_CONST_SIZE,
+	.arg4_type	= ARG_ANYTHING,
+	.arg5_type	= ARG_ANYTHING,
+};
+
 BPF_CALL_5(bpf_sk_lookup_tcp, struct sk_buff *, skb,
 	   struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)
 {
@@ -5289,6 +5334,28 @@ static const struct bpf_func_proto bpf_xdp_sk_lookup_udp_proto = {
 	.arg5_type      = ARG_ANYTHING,
 };
 
+BPF_CALL_5(bpf_xdp_skc_lookup_tcp, struct xdp_buff *, ctx,
+	   struct bpf_sock_tuple *, tuple, u32, len, u32, netns_id, u64, flags)
+{
+	struct net *caller_net = dev_net(ctx->rxq->dev);
+	int ifindex = ctx->rxq->dev->ifindex;
+
+	return __bpf_skc_lookup(NULL, tuple, len, caller_net, ifindex,
+				IPPROTO_TCP, netns_id, flags);
+}
+
+static const struct bpf_func_proto bpf_xdp_skc_lookup_tcp_proto = {
+	.func           = bpf_xdp_skc_lookup_tcp,
+	.gpl_only       = false,
+	.pkt_access     = true,
+	.ret_type       = RET_PTR_TO_SOCK_COMMON_OR_NULL,
+	.arg1_type      = ARG_PTR_TO_CTX,
+	.arg2_type      = ARG_PTR_TO_MEM,
+	.arg3_type      = ARG_CONST_SIZE,
+	.arg4_type      = ARG_ANYTHING,
+	.arg5_type      = ARG_ANYTHING,
+};
+
 BPF_CALL_5(bpf_xdp_sk_lookup_tcp, struct xdp_buff *, ctx,
 	   struct bpf_sock_tuple *, tuple, u32, len, u32, netns_id, u64, flags)
 {
@@ -5311,6 +5378,24 @@ static const struct bpf_func_proto bpf_xdp_sk_lookup_tcp_proto = {
 	.arg5_type      = ARG_ANYTHING,
 };
 
+BPF_CALL_5(bpf_sock_addr_skc_lookup_tcp, struct bpf_sock_addr_kern *, ctx,
+	   struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)
+{
+	return __bpf_skc_lookup(NULL, tuple, len, sock_net(ctx->sk), 0,
+				IPPROTO_TCP, netns_id, flags);
+}
+
+static const struct bpf_func_proto bpf_sock_addr_skc_lookup_tcp_proto = {
+	.func		= bpf_sock_addr_skc_lookup_tcp,
+	.gpl_only	= false,
+	.ret_type	= RET_PTR_TO_SOCK_COMMON_OR_NULL,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_CONST_SIZE,
+	.arg4_type	= ARG_ANYTHING,
+	.arg5_type	= ARG_ANYTHING,
+};
+
 BPF_CALL_5(bpf_sock_addr_sk_lookup_tcp, struct bpf_sock_addr_kern *, ctx,
 	   struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)
 {
@@ -5586,6 +5671,8 @@ sock_addr_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sock_addr_sk_lookup_udp_proto;
 	case BPF_FUNC_sk_release:
 		return &bpf_sk_release_proto;
+	case BPF_FUNC_skc_lookup_tcp:
+		return &bpf_sock_addr_skc_lookup_tcp_proto;
 #endif /* CONFIG_INET */
 	default:
 		return bpf_base_func_proto(func_id);
@@ -5719,6 +5806,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_tcp_sock_proto;
 	case BPF_FUNC_get_listener_sock:
 		return &bpf_get_listener_sock_proto;
+	case BPF_FUNC_skc_lookup_tcp:
+		return &bpf_skc_lookup_tcp_proto;
 #endif
 	default:
 		return bpf_base_func_proto(func_id);
@@ -5754,6 +5843,8 @@ xdp_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_xdp_sk_lookup_tcp_proto;
 	case BPF_FUNC_sk_release:
 		return &bpf_sk_release_proto;
+	case BPF_FUNC_skc_lookup_tcp:
+		return &bpf_xdp_skc_lookup_tcp_proto;
 #endif
 	default:
 		return bpf_base_func_proto(func_id);
@@ -5846,6 +5937,8 @@ sk_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sk_lookup_udp_proto;
 	case BPF_FUNC_sk_release:
 		return &bpf_sk_release_proto;
+	case BPF_FUNC_skc_lookup_tcp:
+		return &bpf_skc_lookup_tcp_proto;
 #endif
 	default:
 		return bpf_base_func_proto(func_id);
-- 
2.19.1

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