xref: /openbmc/linux/net/ipv4/esp4_offload.c (revision ef2b56df) 
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 	skb_pull(skb, offset);
42 
43 	if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
44 		goto out;
45 
46 	xo = xfrm_offload(skb);
47 	if (!xo || !(xo->flags & CRYPTO_DONE)) {
48 		err = secpath_set(skb);
49 		if (err)
50 			goto out;
51 
52 		if (skb->sp->len == XFRM_MAX_DEPTH)
53 			goto out;
54 
55 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
56 				      (xfrm_address_t *)&ip_hdr(skb)->daddr,
57 				      spi, IPPROTO_ESP, AF_INET);
58 		if (!x)
59 			goto out;
60 
61 		skb->sp->xvec[skb->sp->len++] = x;
62 		skb->sp->olen++;
63 
64 		xo = xfrm_offload(skb);
65 		if (!xo) {
66 			xfrm_state_put(x);
67 			goto out;
68 		}
69 	}
70 
71 	xo->flags |= XFRM_GRO;
72 
73 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
74 	XFRM_SPI_SKB_CB(skb)->family = AF_INET;
75 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
76 	XFRM_SPI_SKB_CB(skb)->seq = seq;
77 
78 	/* We don't need to handle errors from xfrm_input, it does all
79 	 * the error handling and frees the resources on error. */
80 	xfrm_input(skb, IPPROTO_ESP, spi, -2);
81 
82 	return ERR_PTR(-EINPROGRESS);
83 out:
84 	skb_push(skb, offset);
85 	NAPI_GRO_CB(skb)->same_flow = 0;
86 	NAPI_GRO_CB(skb)->flush = 1;
87 
88 	return NULL;
89 }
90 
91 static void esp4_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
92 {
93 	struct ip_esp_hdr *esph;
94 	struct iphdr *iph = ip_hdr(skb);
95 	struct xfrm_offload *xo = xfrm_offload(skb);
96 	int proto = iph->protocol;
97 
98 	skb_push(skb, -skb_network_offset(skb));
99 	esph = ip_esp_hdr(skb);
100 	*skb_mac_header(skb) = IPPROTO_ESP;
101 
102 	esph->spi = x->id.spi;
103 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
104 
105 	xo->proto = proto;
106 }
107 
108 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
109 				        netdev_features_t features)
110 {
111 	__u32 seq;
112 	int err = 0;
113 	struct sk_buff *skb2;
114 	struct xfrm_state *x;
115 	struct ip_esp_hdr *esph;
116 	struct crypto_aead *aead;
117 	struct sk_buff *segs = ERR_PTR(-EINVAL);
118 	netdev_features_t esp_features = features;
119 	struct xfrm_offload *xo = xfrm_offload(skb);
120 
121 	if (!xo)
122 		goto out;
123 
124 	seq = xo->seq.low;
125 
126 	x = skb->sp->xvec[skb->sp->len - 1];
127 	aead = x->data;
128 	esph = ip_esp_hdr(skb);
129 
130 	if (esph->spi != x->id.spi)
131 		goto out;
132 
133 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
134 		goto out;
135 
136 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
137 
138 	skb->encap_hdr_csum = 1;
139 
140 	if (!(features & NETIF_F_HW_ESP))
141 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
142 
143 	segs = x->outer_mode->gso_segment(x, skb, esp_features);
144 	if (IS_ERR_OR_NULL(segs))
145 		goto out;
146 
147 	__skb_pull(skb, skb->data - skb_mac_header(skb));
148 
149 	skb2 = segs;
150 	do {
151 		struct sk_buff *nskb = skb2->next;
152 
153 		xo = xfrm_offload(skb2);
154 		xo->flags |= XFRM_GSO_SEGMENT;
155 		xo->seq.low = seq;
156 		xo->seq.hi = xfrm_replay_seqhi(x, seq);
157 
158 		if(!(features & NETIF_F_HW_ESP))
159 			xo->flags |= CRYPTO_FALLBACK;
160 
161 		x->outer_mode->xmit(x, skb2);
162 
163 		err = x->type_offload->xmit(x, skb2, esp_features);
164 		if (err) {
165 			kfree_skb_list(segs);
166 			return ERR_PTR(err);
167 		}
168 
169 		if (!skb_is_gso(skb2))
170 			seq++;
171 		else
172 			seq += skb_shinfo(skb2)->gso_segs;
173 
174 		skb_push(skb2, skb2->mac_len);
175 		skb2 = nskb;
176 	} while (skb2);
177 
178 out:
179 	return segs;
180 }
181 
182 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
183 {
184 	struct crypto_aead *aead = x->data;
185 
186 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
187 		return -EINVAL;
188 
189 	skb->ip_summed = CHECKSUM_NONE;
190 
191 	return esp_input_done2(skb, 0);
192 }
193 
194 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
195 {
196 	int err;
197 	int alen;
198 	int blksize;
199 	struct xfrm_offload *xo;
200 	struct ip_esp_hdr *esph;
201 	struct crypto_aead *aead;
202 	struct esp_info esp;
203 	bool hw_offload = true;
204 
205 	esp.inplace = true;
206 
207 	xo = xfrm_offload(skb);
208 
209 	if (!xo)
210 		return -EINVAL;
211 
212 	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
213 	    (x->xso.dev != skb->dev)) {
214 		xo->flags |= CRYPTO_FALLBACK;
215 		hw_offload = false;
216 	}
217 
218 	esp.proto = xo->proto;
219 
220 	/* skb is pure payload to encrypt */
221 
222 	aead = x->data;
223 	alen = crypto_aead_authsize(aead);
224 
225 	esp.tfclen = 0;
226 	/* XXX: Add support for tfc padding here. */
227 
228 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
229 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
230 	esp.plen = esp.clen - skb->len - esp.tfclen;
231 	esp.tailen = esp.tfclen + esp.plen + alen;
232 
233 	esp.esph = ip_esp_hdr(skb);
234 
235 
236 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
237 		esp.nfrags = esp_output_head(x, skb, &esp);
238 		if (esp.nfrags < 0)
239 			return esp.nfrags;
240 	}
241 
242 	esph = esp.esph;
243 	esph->spi = x->id.spi;
244 
245 	skb_push(skb, -skb_network_offset(skb));
246 
247 	if (xo->flags & XFRM_GSO_SEGMENT) {
248 		esph->seq_no = htonl(xo->seq.low);
249 	} else {
250 		ip_hdr(skb)->tot_len = htons(skb->len);
251 		ip_send_check(ip_hdr(skb));
252 	}
253 
254 	if (hw_offload)
255 		return 0;
256 
257 	esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
258 
259 	err = esp_output_tail(x, skb, &esp);
260 	if (err < 0)
261 		return err;
262 
263 	secpath_reset(skb);
264 
265 	return 0;
266 }
267 
268 static const struct net_offload esp4_offload = {
269 	.callbacks = {
270 		.gro_receive = esp4_gro_receive,
271 		.gso_segment = esp4_gso_segment,
272 	},
273 };
274 
275 static const struct xfrm_type_offload esp_type_offload = {
276 	.description	= "ESP4 OFFLOAD",
277 	.owner		= THIS_MODULE,
278 	.proto	     	= IPPROTO_ESP,
279 	.input_tail	= esp_input_tail,
280 	.xmit		= esp_xmit,
281 	.encap		= esp4_gso_encap,
282 };
283 
284 static int __init esp4_offload_init(void)
285 {
286 	if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
287 		pr_info("%s: can't add xfrm type offload\n", __func__);
288 		return -EAGAIN;
289 	}
290 
291 	return inet_add_offload(&esp4_offload, IPPROTO_ESP);
292 }
293 
294 static void __exit esp4_offload_exit(void)
295 {
296 	if (xfrm_unregister_type_offload(&esp_type_offload, AF_INET) < 0)
297 		pr_info("%s: can't remove xfrm type offload\n", __func__);
298 
299 	inet_del_offload(&esp4_offload, IPPROTO_ESP);
300 }
301 
302 module_init(esp4_offload_init);
303 module_exit(esp4_offload_exit);
304 MODULE_LICENSE("GPL");
305 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
306