netdev - [RFC PATCH 05/24] bpf: added bpf_xdpsk

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Message-Id: <20180131135356.19134-6-bjorn.topel@gmail.com>
Date:   Wed, 31 Jan 2018 14:53:37 +0100
From:   Björn Töpel <bjorn.topel@...il.com>
To:     bjorn.topel@...il.com, magnus.karlsson@...el.com,
        alexander.h.duyck@...el.com, alexander.duyck@...il.com,
        john.fastabend@...il.com, ast@...com, brouer@...hat.com,
        willemdebruijn.kernel@...il.com, daniel@...earbox.net,
        netdev@...r.kernel.org
Cc:     Björn Töpel <bjorn.topel@...el.com>,
        michael.lundkvist@...csson.com, jesse.brandeburg@...el.com,
        anjali.singhai@...el.com, jeffrey.b.shaw@...el.com,
        ferruh.yigit@...el.com, qi.z.zhang@...el.com
Subject: [RFC PATCH 05/24] bpf: added bpf_xdpsk_redirect

From: Björn Töpel <bjorn.topel@...el.com>

The bpf_xdpsk_redirect call redirects the XDP context to the XDP
socket bound to the receiving queue (if any).

Signed-off-by: Björn Töpel <bjorn.topel@...el.com>
---
 include/uapi/linux/bpf.h                  |  6 +++++-
 net/core/filter.c                         | 24 ++++++++++++++++++++++++
 tools/testing/selftests/bpf/bpf_helpers.h |  2 ++
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index db6bdc375126..18f9ee7cb529 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -696,6 +696,9 @@ union bpf_attr {
  * int bpf_override_return(pt_regs, rc)
  *	@pt_regs: pointer to struct pt_regs
  *	@rc: the return value to set
+ *
+ * int bpf_xdpsk_redirect()
+ *	Return: XDP_REDIRECT
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -757,7 +760,8 @@ union bpf_attr {
 	FN(perf_prog_read_value),	\
 	FN(getsockopt),			\
 	FN(override_return),		\
-	FN(sock_ops_cb_flags_set),
+	FN(sock_ops_cb_flags_set),	\
+	FN(xdpsk_redirect),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
diff --git a/net/core/filter.c b/net/core/filter.c
index 08ab4c65a998..aedf57489cb5 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1809,6 +1809,8 @@ struct redirect_info {
 	struct bpf_map *map;
 	struct bpf_map *map_to_flush;
 	unsigned long   map_owner;
+	bool to_xsk;
+	/* XXX cache xsk socket here, to avoid lookup? */
 };
 
 static DEFINE_PER_CPU(struct redirect_info, redirect_info);
@@ -2707,6 +2709,7 @@ static int xdp_do_generic_redirect_map(struct net_device *dev,
 	ri->ifindex = 0;
 	ri->map = NULL;
 	ri->map_owner = 0;
+	ri->to_xsk = false;
 
 	if (unlikely(xdp_map_invalid(xdp_prog, map_owner))) {
 		err = -EFAULT;
@@ -2817,6 +2820,25 @@ static const struct bpf_func_proto bpf_xdp_redirect_map_proto = {
 	.arg3_type      = ARG_ANYTHING,
 };
 
+BPF_CALL_0(bpf_xdpsk_redirect)
+{
+	struct redirect_info *ri = this_cpu_ptr(&redirect_info);
+
+	/* XXX Would it be better to check for socket existence here,
+	 * and XDP_ABORTED on failure? Also, then we can populate xsk
+	 * in ri, and don't have to do the lookup multiple times.
+	 */
+	ri->to_xsk = true;
+
+	return XDP_REDIRECT;
+}
+
+static const struct bpf_func_proto bpf_xdpsk_redirect_proto = {
+	.func		= bpf_xdpsk_redirect,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+};
+
 bool bpf_helper_changes_pkt_data(void *func)
 {
 	if (func == bpf_skb_vlan_push ||
@@ -3544,6 +3566,8 @@ xdp_func_proto(enum bpf_func_id func_id)
 		return &bpf_xdp_redirect_proto;
 	case BPF_FUNC_redirect_map:
 		return &bpf_xdp_redirect_map_proto;
+	case BPF_FUNC_xdpsk_redirect:
+		return &bpf_xdpsk_redirect_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index dde2c11d7771..5898ad7a8e40 100644
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -86,6 +86,8 @@ static int (*bpf_perf_prog_read_value)(void *ctx, void *buf,
 	(void *) BPF_FUNC_perf_prog_read_value;
 static int (*bpf_override_return)(void *ctx, unsigned long rc) =
 	(void *) BPF_FUNC_override_return;
+static int (*bpf_xdpsk_redirect)(void) =
+	(void *) BPF_FUNC_xdpsk_redirect;
 
 /* llvm builtin functions that eBPF C program may use to
  * emit BPF_LD_ABS and BPF_LD_IND instructions
-- 
2.14.1