netdev - [PATCH v2 net-next 7/9] bpf: helpers: add multibuffer support

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Date:   Thu,  3 Sep 2020 22:58:51 +0200
From:   Lorenzo Bianconi <lorenzo@...nel.org>
To:     netdev@...r.kernel.org
Cc:     bpf@...r.kernel.org, davem@...emloft.net,
        lorenzo.bianconi@...hat.com, brouer@...hat.com,
        echaudro@...hat.com, sameehj@...zon.com, kuba@...nel.org,
        john.fastabend@...il.com, daniel@...earbox.net, ast@...nel.org,
        shayagr@...zon.com
Subject: [PATCH v2 net-next 7/9] bpf: helpers: add multibuffer support

From: Sameeh Jubran <sameehj@...zon.com>

The implementation is based on this [0] draft by Jesper D. Brouer.

Provided two new helpers:

* bpf_xdp_get_frag_count()
* bpf_xdp_get_frags_total_size()

[0] xdp mb design - https://github.com/xdp-project/xdp-project/blob/master/areas/core/xdp-multi-buffer01-design.org
Signed-off-by: Sameeh Jubran <sameehj@...zon.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
 include/uapi/linux/bpf.h       | 14 ++++++++++++
 net/core/filter.c              | 39 ++++++++++++++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h | 14 ++++++++++++
 3 files changed, 67 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c4a6d245619c..53db75095306 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3590,6 +3590,18 @@ union bpf_attr {
  *
  *	Return
  *		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_xdp_get_frag_count(struct xdp_buff *xdp_md)
+ *	Description
+ *		Get the total number of frags for a given packet.
+ *	Return
+ *		The number of frags
+ *
+ * int bpf_xdp_get_frags_total_size(struct xdp_buff *xdp_md)
+ *	Description
+ *		Get the total size of frags for a given packet.
+ *	Return
+ *		The total size of frags for a given packet.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -3742,6 +3754,8 @@ union bpf_attr {
 	FN(d_path),			\
 	FN(copy_from_user),		\
 	FN(xdp_adjust_mb_header),	\
+	FN(xdp_get_frag_count),		\
+	FN(xdp_get_frags_total_size),	\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/net/core/filter.c b/net/core/filter.c
index ae6b10cf062d..ba058fc16440 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3526,6 +3526,41 @@ static const struct bpf_func_proto bpf_xdp_adjust_mb_header_proto = {
 	.arg2_type	= ARG_ANYTHING,
 };
 
+BPF_CALL_1(bpf_xdp_get_frag_count, struct  xdp_buff*, xdp)
+{
+	struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
+
+	return xdp->mb ? sinfo->nr_frags : 0;
+}
+
+const struct bpf_func_proto bpf_xdp_get_frag_count_proto = {
+	.func		= bpf_xdp_get_frag_count,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+};
+
+BPF_CALL_1(bpf_xdp_get_frags_total_size, struct  xdp_buff*, xdp)
+{
+	struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
+	int nfrags, i;
+	int size = 0;
+
+	nfrags = xdp->mb ? sinfo->nr_frags : 0;
+
+	for (i = 0; i < nfrags && i < MAX_SKB_FRAGS; i++)
+		size += skb_frag_size(&sinfo->frags[i]);
+
+	return size;
+}
+
+const struct bpf_func_proto bpf_xdp_get_frags_total_size_proto = {
+	.func		= bpf_xdp_get_frags_total_size,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+};
+
 BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset)
 {
 	void *data_hard_end = xdp_data_hard_end(xdp); /* use xdp->frame_sz */
@@ -6889,6 +6924,10 @@ xdp_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_xdp_adjust_tail_proto;
 	case BPF_FUNC_xdp_adjust_mb_header:
 		return &bpf_xdp_adjust_mb_header_proto;
+	case BPF_FUNC_xdp_get_frag_count:
+		return &bpf_xdp_get_frag_count_proto;
+	case BPF_FUNC_xdp_get_frags_total_size:
+		return &bpf_xdp_get_frags_total_size_proto;
 	case BPF_FUNC_fib_lookup:
 		return &bpf_xdp_fib_lookup_proto;
 #ifdef CONFIG_INET
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 392d52a2ecef..dd4669096cbb 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3591,6 +3591,18 @@ union bpf_attr {
  *
  *	Return
  *		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_xdp_get_frag_count(struct xdp_buff *xdp_md)
+ *	Description
+ *		Get the total number of frags for a given packet.
+ *	Return
+ *		The number of frags
+ *
+ * int bpf_xdp_get_frags_total_size(struct xdp_buff *xdp_md)
+ *	Description
+ *		Get the total size of frags for a given packet.
+ *	Return
+ *		The total size of frags for a given packet.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -3743,6 +3755,8 @@ union bpf_attr {
 	FN(d_path),			\
 	FN(copy_from_user),		\
 	FN(xdp_adjust_mb_header),	\
+	FN(xdp_get_frag_count),		\
+	FN(xdp_get_frags_total_size),	\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
-- 
2.26.2