1 /*
2  * net/ife/ife.c - Inter-FE protocol based on ForCES WG InterFE LFB
3  * Copyright (c) 2015 Jamal Hadi Salim <jhs@mojatatu.com>
4  * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
5  *
6  * Refer to: draft-ietf-forces-interfelfb-03 and netdev01 paper:
7  * "Distributing Linux Traffic Control Classifier-Action Subsystem"
8  * Authors: Jamal Hadi Salim and Damascene M. Joachimpillai
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published by
12  * the Free Software Foundation.
13  */
14 
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/string.h>
18 #include <linux/errno.h>
19 #include <linux/skbuff.h>
20 #include <linux/rtnetlink.h>
21 #include <linux/module.h>
22 #include <linux/init.h>
23 #include <net/net_namespace.h>
24 #include <net/netlink.h>
25 #include <net/pkt_sched.h>
26 #include <linux/etherdevice.h>
27 #include <net/ife.h>
28 
29 struct ifeheadr {
30 	__be16 metalen;
31 	u8 tlv_data[];
32 };
33 
ife_encode(struct sk_buff * skb,u16 metalen)34 void *ife_encode(struct sk_buff *skb, u16 metalen)
35 {
36 	/* OUTERHDR:TOTMETALEN:{TLVHDR:Metadatum:TLVHDR..}:ORIGDATA
37 	 * where ORIGDATA = original ethernet header ...
38 	 */
39 	int hdrm = metalen + IFE_METAHDRLEN;
40 	int total_push = hdrm + skb->dev->hard_header_len;
41 	struct ifeheadr *ifehdr;
42 	struct ethhdr *iethh;	/* inner ether header */
43 	int skboff = 0;
44 	int err;
45 
46 	err = skb_cow_head(skb, total_push);
47 	if (unlikely(err))
48 		return NULL;
49 
50 	iethh = (struct ethhdr *) skb->data;
51 
52 	__skb_push(skb, total_push);
53 	memcpy(skb->data, iethh, skb->dev->hard_header_len);
54 	skb_reset_mac_header(skb);
55 	skboff += skb->dev->hard_header_len;
56 
57 	/* total metadata length */
58 	ifehdr = (struct ifeheadr *) (skb->data + skboff);
59 	metalen += IFE_METAHDRLEN;
60 	ifehdr->metalen = htons(metalen);
61 
62 	return ifehdr->tlv_data;
63 }
64 EXPORT_SYMBOL_GPL(ife_encode);
65 
ife_decode(struct sk_buff * skb,u16 * metalen)66 void *ife_decode(struct sk_buff *skb, u16 *metalen)
67 {
68 	struct ifeheadr *ifehdr;
69 	int total_pull;
70 	u16 ifehdrln;
71 
72 	if (!pskb_may_pull(skb, skb->dev->hard_header_len + IFE_METAHDRLEN))
73 		return NULL;
74 
75 	ifehdr = (struct ifeheadr *) (skb->data + skb->dev->hard_header_len);
76 	ifehdrln = ntohs(ifehdr->metalen);
77 	total_pull = skb->dev->hard_header_len + ifehdrln;
78 
79 	if (unlikely(ifehdrln < 2))
80 		return NULL;
81 
82 	if (unlikely(!pskb_may_pull(skb, total_pull)))
83 		return NULL;
84 
85 	skb_set_mac_header(skb, total_pull);
86 	__skb_pull(skb, total_pull);
87 	*metalen = ifehdrln - IFE_METAHDRLEN;
88 
89 	return &ifehdr->tlv_data;
90 }
91 EXPORT_SYMBOL_GPL(ife_decode);
92 
93 struct meta_tlvhdr {
94 	__be16 type;
95 	__be16 len;
96 };
97 
__ife_tlv_meta_valid(const unsigned char * skbdata,const unsigned char * ifehdr_end)98 static bool __ife_tlv_meta_valid(const unsigned char *skbdata,
99 				 const unsigned char *ifehdr_end)
100 {
101 	const struct meta_tlvhdr *tlv;
102 	u16 tlvlen;
103 
104 	if (unlikely(skbdata + sizeof(*tlv) > ifehdr_end))
105 		return false;
106 
107 	tlv = (const struct meta_tlvhdr *)skbdata;
108 	tlvlen = ntohs(tlv->len);
109 
110 	/* tlv length field is inc header, check on minimum */
111 	if (tlvlen < NLA_HDRLEN)
112 		return false;
113 
114 	/* overflow by NLA_ALIGN check */
115 	if (NLA_ALIGN(tlvlen) < tlvlen)
116 		return false;
117 
118 	if (unlikely(skbdata + NLA_ALIGN(tlvlen) > ifehdr_end))
119 		return false;
120 
121 	return true;
122 }
123 
124 /* Caller takes care of presenting data in network order
125  */
ife_tlv_meta_decode(void * skbdata,const void * ifehdr_end,u16 * attrtype,u16 * dlen,u16 * totlen)126 void *ife_tlv_meta_decode(void *skbdata, const void *ifehdr_end, u16 *attrtype,
127 			  u16 *dlen, u16 *totlen)
128 {
129 	struct meta_tlvhdr *tlv;
130 
131 	if (!__ife_tlv_meta_valid(skbdata, ifehdr_end))
132 		return NULL;
133 
134 	tlv = (struct meta_tlvhdr *)skbdata;
135 	*dlen = ntohs(tlv->len) - NLA_HDRLEN;
136 	*attrtype = ntohs(tlv->type);
137 
138 	if (totlen)
139 		*totlen = nla_total_size(*dlen);
140 
141 	return skbdata + sizeof(struct meta_tlvhdr);
142 }
143 EXPORT_SYMBOL_GPL(ife_tlv_meta_decode);
144 
ife_tlv_meta_next(void * skbdata)145 void *ife_tlv_meta_next(void *skbdata)
146 {
147 	struct meta_tlvhdr *tlv = (struct meta_tlvhdr *) skbdata;
148 	u16 tlvlen = ntohs(tlv->len);
149 
150 	tlvlen = NLA_ALIGN(tlvlen);
151 
152 	return skbdata + tlvlen;
153 }
154 EXPORT_SYMBOL_GPL(ife_tlv_meta_next);
155 
156 /* Caller takes care of presenting data in network order
157  */
ife_tlv_meta_encode(void * skbdata,u16 attrtype,u16 dlen,const void * dval)158 int ife_tlv_meta_encode(void *skbdata, u16 attrtype, u16 dlen, const void *dval)
159 {
160 	__be32 *tlv = (__be32 *) (skbdata);
161 	u16 totlen = nla_total_size(dlen);	/*alignment + hdr */
162 	char *dptr = (char *) tlv + NLA_HDRLEN;
163 	u32 htlv = attrtype << 16 | (dlen + NLA_HDRLEN);
164 
165 	*tlv = htonl(htlv);
166 	memset(dptr, 0, totlen - NLA_HDRLEN);
167 	memcpy(dptr, dval, dlen);
168 
169 	return totlen;
170 }
171 EXPORT_SYMBOL_GPL(ife_tlv_meta_encode);
172 
173 MODULE_AUTHOR("Jamal Hadi Salim <jhs@mojatatu.com>");
174 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
175 MODULE_DESCRIPTION("Inter-FE LFB action");
176 MODULE_LICENSE("GPL");
177