xref: /openbmc/linux/net/ipv4/esp4_offload.c (revision ae213c44) 
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 list_head *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 		struct sec_path *sp = secpath_set(skb);
50 
51 		if (!sp)
52 			goto out;
53 
54 		if (sp->len == XFRM_MAX_DEPTH)
55 			goto out_reset;
56 
57 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
58 				      (xfrm_address_t *)&ip_hdr(skb)->daddr,
59 				      spi, IPPROTO_ESP, AF_INET);
60 		if (!x)
61 			goto out_reset;
62 
63 		sp->xvec[sp->len++] = x;
64 		sp->olen++;
65 
66 		xo = xfrm_offload(skb);
67 		if (!xo) {
68 			xfrm_state_put(x);
69 			goto out_reset;
70 		}
71 	}
72 
73 	xo->flags |= XFRM_GRO;
74 
75 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
76 	XFRM_SPI_SKB_CB(skb)->family = AF_INET;
77 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
78 	XFRM_SPI_SKB_CB(skb)->seq = seq;
79 
80 	/* We don't need to handle errors from xfrm_input, it does all
81 	 * the error handling and frees the resources on error. */
82 	xfrm_input(skb, IPPROTO_ESP, spi, -2);
83 
84 	return ERR_PTR(-EINPROGRESS);
85 out_reset:
86 	secpath_reset(skb);
87 out:
88 	skb_push(skb, offset);
89 	NAPI_GRO_CB(skb)->same_flow = 0;
90 	NAPI_GRO_CB(skb)->flush = 1;
91 
92 	return NULL;
93 }
94 
95 static void esp4_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
96 {
97 	struct ip_esp_hdr *esph;
98 	struct iphdr *iph = ip_hdr(skb);
99 	struct xfrm_offload *xo = xfrm_offload(skb);
100 	int proto = iph->protocol;
101 
102 	skb_push(skb, -skb_network_offset(skb));
103 	esph = ip_esp_hdr(skb);
104 	*skb_mac_header(skb) = IPPROTO_ESP;
105 
106 	esph->spi = x->id.spi;
107 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
108 
109 	xo->proto = proto;
110 }
111 
112 static struct sk_buff *xfrm4_tunnel_gso_segment(struct xfrm_state *x,
113 						struct sk_buff *skb,
114 						netdev_features_t features)
115 {
116 	__skb_push(skb, skb->mac_len);
117 	return skb_mac_gso_segment(skb, features);
118 }
119 
120 static struct sk_buff *xfrm4_transport_gso_segment(struct xfrm_state *x,
121 						   struct sk_buff *skb,
122 						   netdev_features_t features)
123 {
124 	const struct net_offload *ops;
125 	struct sk_buff *segs = ERR_PTR(-EINVAL);
126 	struct xfrm_offload *xo = xfrm_offload(skb);
127 
128 	skb->transport_header += x->props.header_len;
129 	ops = rcu_dereference(inet_offloads[xo->proto]);
130 	if (likely(ops && ops->callbacks.gso_segment))
131 		segs = ops->callbacks.gso_segment(skb, features);
132 
133 	return segs;
134 }
135 
136 static struct sk_buff *xfrm4_outer_mode_gso_segment(struct xfrm_state *x,
137 						    struct sk_buff *skb,
138 						    netdev_features_t features)
139 {
140 	switch (x->outer_mode.encap) {
141 	case XFRM_MODE_TUNNEL:
142 		return xfrm4_tunnel_gso_segment(x, skb, features);
143 	case XFRM_MODE_TRANSPORT:
144 		return xfrm4_transport_gso_segment(x, skb, features);
145 	}
146 
147 	return ERR_PTR(-EOPNOTSUPP);
148 }
149 
150 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
151 				        netdev_features_t features)
152 {
153 	struct xfrm_state *x;
154 	struct ip_esp_hdr *esph;
155 	struct crypto_aead *aead;
156 	netdev_features_t esp_features = features;
157 	struct xfrm_offload *xo = xfrm_offload(skb);
158 	struct sec_path *sp;
159 
160 	if (!xo)
161 		return ERR_PTR(-EINVAL);
162 
163 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
164 		return ERR_PTR(-EINVAL);
165 
166 	sp = skb_sec_path(skb);
167 	x = sp->xvec[sp->len - 1];
168 	aead = x->data;
169 	esph = ip_esp_hdr(skb);
170 
171 	if (esph->spi != x->id.spi)
172 		return ERR_PTR(-EINVAL);
173 
174 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
175 		return ERR_PTR(-EINVAL);
176 
177 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
178 
179 	skb->encap_hdr_csum = 1;
180 
181 	if ((!(skb->dev->gso_partial_features & NETIF_F_HW_ESP) &&
182 	     !(features & NETIF_F_HW_ESP)) || x->xso.dev != skb->dev)
183 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
184 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM) &&
185 		 !(skb->dev->gso_partial_features & NETIF_F_HW_ESP_TX_CSUM))
186 		esp_features = features & ~NETIF_F_CSUM_MASK;
187 
188 	xo->flags |= XFRM_GSO_SEGMENT;
189 
190 	return xfrm4_outer_mode_gso_segment(x, skb, esp_features);
191 }
192 
193 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
194 {
195 	struct crypto_aead *aead = x->data;
196 	struct xfrm_offload *xo = xfrm_offload(skb);
197 
198 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
199 		return -EINVAL;
200 
201 	if (!(xo->flags & CRYPTO_DONE))
202 		skb->ip_summed = CHECKSUM_NONE;
203 
204 	return esp_input_done2(skb, 0);
205 }
206 
207 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
208 {
209 	int err;
210 	int alen;
211 	int blksize;
212 	struct xfrm_offload *xo;
213 	struct ip_esp_hdr *esph;
214 	struct crypto_aead *aead;
215 	struct esp_info esp;
216 	bool hw_offload = true;
217 	__u32 seq;
218 
219 	esp.inplace = true;
220 
221 	xo = xfrm_offload(skb);
222 
223 	if (!xo)
224 		return -EINVAL;
225 
226 	if ((!(features & NETIF_F_HW_ESP) &&
227 	     !(skb->dev->gso_partial_features & NETIF_F_HW_ESP)) ||
228 	    x->xso.dev != skb->dev) {
229 		xo->flags |= CRYPTO_FALLBACK;
230 		hw_offload = false;
231 	}
232 
233 	esp.proto = xo->proto;
234 
235 	/* skb is pure payload to encrypt */
236 
237 	aead = x->data;
238 	alen = crypto_aead_authsize(aead);
239 
240 	esp.tfclen = 0;
241 	/* XXX: Add support for tfc padding here. */
242 
243 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
244 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
245 	esp.plen = esp.clen - skb->len - esp.tfclen;
246 	esp.tailen = esp.tfclen + esp.plen + alen;
247 
248 	esp.esph = ip_esp_hdr(skb);
249 
250 
251 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
252 		esp.nfrags = esp_output_head(x, skb, &esp);
253 		if (esp.nfrags < 0)
254 			return esp.nfrags;
255 	}
256 
257 	seq = xo->seq.low;
258 
259 	esph = esp.esph;
260 	esph->spi = x->id.spi;
261 
262 	skb_push(skb, -skb_network_offset(skb));
263 
264 	if (xo->flags & XFRM_GSO_SEGMENT) {
265 		esph->seq_no = htonl(seq);
266 
267 		if (!skb_is_gso(skb))
268 			xo->seq.low++;
269 		else
270 			xo->seq.low += skb_shinfo(skb)->gso_segs;
271 	}
272 
273 	esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
274 
275 	ip_hdr(skb)->tot_len = htons(skb->len);
276 	ip_send_check(ip_hdr(skb));
277 
278 	if (hw_offload)
279 		return 0;
280 
281 	err = esp_output_tail(x, skb, &esp);
282 	if (err)
283 		return err;
284 
285 	secpath_reset(skb);
286 
287 	return 0;
288 }
289 
290 static const struct net_offload esp4_offload = {
291 	.callbacks = {
292 		.gro_receive = esp4_gro_receive,
293 		.gso_segment = esp4_gso_segment,
294 	},
295 };
296 
297 static const struct xfrm_type_offload esp_type_offload = {
298 	.description	= "ESP4 OFFLOAD",
299 	.owner		= THIS_MODULE,
300 	.proto	     	= IPPROTO_ESP,
301 	.input_tail	= esp_input_tail,
302 	.xmit		= esp_xmit,
303 	.encap		= esp4_gso_encap,
304 };
305 
306 static int __init esp4_offload_init(void)
307 {
308 	if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
309 		pr_info("%s: can't add xfrm type offload\n", __func__);
310 		return -EAGAIN;
311 	}
312 
313 	return inet_add_offload(&esp4_offload, IPPROTO_ESP);
314 }
315 
316 static void __exit esp4_offload_exit(void)
317 {
318 	if (xfrm_unregister_type_offload(&esp_type_offload, AF_INET) < 0)
319 		pr_info("%s: can't remove xfrm type offload\n", __func__);
320 
321 	inet_del_offload(&esp4_offload, IPPROTO_ESP);
322 }
323 
324 module_init(esp4_offload_init);
325 module_exit(esp4_offload_exit);
326 MODULE_LICENSE("GPL");
327 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
328 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);
329