xref: /openbmc/linux/net/ipv4/esp4_offload.c (revision 82e6fdd6) 
1 /*
2  * IPV4 GSO/GRO offload support
3  * Linux INET implementation
4  *
5  * Copyright (C) 2016 secunet Security Networks AG
6  * Author: Steffen Klassert <steffen.klassert@secunet.com>
7  *
8  * This program is free software; you can redistribute it and/or modify it
9  * under the terms and conditions of the GNU General Public License,
10  * version 2, as published by the Free Software Foundation.
11  *
12  * ESP GRO support
13  */
14 
15 #include <linux/skbuff.h>
16 #include <linux/init.h>
17 #include <net/protocol.h>
18 #include <crypto/aead.h>
19 #include <crypto/authenc.h>
20 #include <linux/err.h>
21 #include <linux/module.h>
22 #include <net/ip.h>
23 #include <net/xfrm.h>
24 #include <net/esp.h>
25 #include <linux/scatterlist.h>
26 #include <linux/kernel.h>
27 #include <linux/slab.h>
28 #include <linux/spinlock.h>
29 #include <net/udp.h>
30 
31 static struct sk_buff **esp4_gro_receive(struct sk_buff **head,
32 					 struct sk_buff *skb)
33 {
34 	int offset = skb_gro_offset(skb);
35 	struct xfrm_offload *xo;
36 	struct xfrm_state *x;
37 	__be32 seq;
38 	__be32 spi;
39 	int err;
40 
41 	if (!pskb_pull(skb, offset))
42 		return NULL;
43 
44 	if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
45 		goto out;
46 
47 	xo = xfrm_offload(skb);
48 	if (!xo || !(xo->flags & CRYPTO_DONE)) {
49 		err = secpath_set(skb);
50 		if (err)
51 			goto out;
52 
53 		if (skb->sp->len == XFRM_MAX_DEPTH)
54 			goto out;
55 
56 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
57 				      (xfrm_address_t *)&ip_hdr(skb)->daddr,
58 				      spi, IPPROTO_ESP, AF_INET);
59 		if (!x)
60 			goto out;
61 
62 		skb->sp->xvec[skb->sp->len++] = x;
63 		skb->sp->olen++;
64 
65 		xo = xfrm_offload(skb);
66 		if (!xo) {
67 			xfrm_state_put(x);
68 			goto out;
69 		}
70 	}
71 
72 	xo->flags |= XFRM_GRO;
73 
74 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
75 	XFRM_SPI_SKB_CB(skb)->family = AF_INET;
76 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
77 	XFRM_SPI_SKB_CB(skb)->seq = seq;
78 
79 	/* We don't need to handle errors from xfrm_input, it does all
80 	 * the error handling and frees the resources on error. */
81 	xfrm_input(skb, IPPROTO_ESP, spi, -2);
82 
83 	return ERR_PTR(-EINPROGRESS);
84 out:
85 	skb_push(skb, offset);
86 	NAPI_GRO_CB(skb)->same_flow = 0;
87 	NAPI_GRO_CB(skb)->flush = 1;
88 
89 	return NULL;
90 }
91 
92 static void esp4_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
93 {
94 	struct ip_esp_hdr *esph;
95 	struct iphdr *iph = ip_hdr(skb);
96 	struct xfrm_offload *xo = xfrm_offload(skb);
97 	int proto = iph->protocol;
98 
99 	skb_push(skb, -skb_network_offset(skb));
100 	esph = ip_esp_hdr(skb);
101 	*skb_mac_header(skb) = IPPROTO_ESP;
102 
103 	esph->spi = x->id.spi;
104 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
105 
106 	xo->proto = proto;
107 }
108 
109 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
110 				        netdev_features_t features)
111 {
112 	struct xfrm_state *x;
113 	struct ip_esp_hdr *esph;
114 	struct crypto_aead *aead;
115 	netdev_features_t esp_features = features;
116 	struct xfrm_offload *xo = xfrm_offload(skb);
117 
118 	if (!xo)
119 		return ERR_PTR(-EINVAL);
120 
121 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
122 		return ERR_PTR(-EINVAL);
123 
124 	x = skb->sp->xvec[skb->sp->len - 1];
125 	aead = x->data;
126 	esph = ip_esp_hdr(skb);
127 
128 	if (esph->spi != x->id.spi)
129 		return ERR_PTR(-EINVAL);
130 
131 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
132 		return ERR_PTR(-EINVAL);
133 
134 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
135 
136 	skb->encap_hdr_csum = 1;
137 
138 	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
139 	    (x->xso.dev != skb->dev))
140 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
141 
142 	xo->flags |= XFRM_GSO_SEGMENT;
143 
144 	return x->outer_mode->gso_segment(x, skb, esp_features);
145 }
146 
147 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
148 {
149 	struct crypto_aead *aead = x->data;
150 	struct xfrm_offload *xo = xfrm_offload(skb);
151 
152 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
153 		return -EINVAL;
154 
155 	if (!(xo->flags & CRYPTO_DONE))
156 		skb->ip_summed = CHECKSUM_NONE;
157 
158 	return esp_input_done2(skb, 0);
159 }
160 
161 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
162 {
163 	int err;
164 	int alen;
165 	int blksize;
166 	struct xfrm_offload *xo;
167 	struct ip_esp_hdr *esph;
168 	struct crypto_aead *aead;
169 	struct esp_info esp;
170 	bool hw_offload = true;
171 	__u32 seq;
172 
173 	esp.inplace = true;
174 
175 	xo = xfrm_offload(skb);
176 
177 	if (!xo)
178 		return -EINVAL;
179 
180 	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
181 	    (x->xso.dev != skb->dev)) {
182 		xo->flags |= CRYPTO_FALLBACK;
183 		hw_offload = false;
184 	}
185 
186 	esp.proto = xo->proto;
187 
188 	/* skb is pure payload to encrypt */
189 
190 	aead = x->data;
191 	alen = crypto_aead_authsize(aead);
192 
193 	esp.tfclen = 0;
194 	/* XXX: Add support for tfc padding here. */
195 
196 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
197 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
198 	esp.plen = esp.clen - skb->len - esp.tfclen;
199 	esp.tailen = esp.tfclen + esp.plen + alen;
200 
201 	esp.esph = ip_esp_hdr(skb);
202 
203 
204 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
205 		esp.nfrags = esp_output_head(x, skb, &esp);
206 		if (esp.nfrags < 0)
207 			return esp.nfrags;
208 	}
209 
210 	seq = xo->seq.low;
211 
212 	esph = esp.esph;
213 	esph->spi = x->id.spi;
214 
215 	skb_push(skb, -skb_network_offset(skb));
216 
217 	if (xo->flags & XFRM_GSO_SEGMENT) {
218 		esph->seq_no = htonl(seq);
219 
220 		if (!skb_is_gso(skb))
221 			xo->seq.low++;
222 		else
223 			xo->seq.low += skb_shinfo(skb)->gso_segs;
224 	}
225 
226 	esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
227 
228 	ip_hdr(skb)->tot_len = htons(skb->len);
229 	ip_send_check(ip_hdr(skb));
230 
231 	if (hw_offload)
232 		return 0;
233 
234 	err = esp_output_tail(x, skb, &esp);
235 	if (err)
236 		return err;
237 
238 	secpath_reset(skb);
239 
240 	return 0;
241 }
242 
243 static const struct net_offload esp4_offload = {
244 	.callbacks = {
245 		.gro_receive = esp4_gro_receive,
246 		.gso_segment = esp4_gso_segment,
247 	},
248 };
249 
250 static const struct xfrm_type_offload esp_type_offload = {
251 	.description	= "ESP4 OFFLOAD",
252 	.owner		= THIS_MODULE,
253 	.proto	     	= IPPROTO_ESP,
254 	.input_tail	= esp_input_tail,
255 	.xmit		= esp_xmit,
256 	.encap		= esp4_gso_encap,
257 };
258 
259 static int __init esp4_offload_init(void)
260 {
261 	if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
262 		pr_info("%s: can't add xfrm type offload\n", __func__);
263 		return -EAGAIN;
264 	}
265 
266 	return inet_add_offload(&esp4_offload, IPPROTO_ESP);
267 }
268 
269 static void __exit esp4_offload_exit(void)
270 {
271 	if (xfrm_unregister_type_offload(&esp_type_offload, AF_INET) < 0)
272 		pr_info("%s: can't remove xfrm type offload\n", __func__);
273 
274 	inet_del_offload(&esp4_offload, IPPROTO_ESP);
275 }
276 
277 module_init(esp4_offload_init);
278 module_exit(esp4_offload_exit);
279 MODULE_LICENSE("GPL");
280 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
281 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);
282