xref: /openbmc/linux/net/ipv4/esp4_offload.c (revision 15e3ae36) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * IPV4 GSO/GRO offload support
4  * Linux INET implementation
5  *
6  * Copyright (C) 2016 secunet Security Networks AG
7  * Author: Steffen Klassert <steffen.klassert@secunet.com>
8  *
9  * ESP GRO support
10  */
11 
12 #include <linux/skbuff.h>
13 #include <linux/init.h>
14 #include <net/protocol.h>
15 #include <crypto/aead.h>
16 #include <crypto/authenc.h>
17 #include <linux/err.h>
18 #include <linux/module.h>
19 #include <net/ip.h>
20 #include <net/xfrm.h>
21 #include <net/esp.h>
22 #include <linux/scatterlist.h>
23 #include <linux/kernel.h>
24 #include <linux/slab.h>
25 #include <linux/spinlock.h>
26 #include <net/udp.h>
27 
28 static struct sk_buff *esp4_gro_receive(struct list_head *head,
29 					struct sk_buff *skb)
30 {
31 	int offset = skb_gro_offset(skb);
32 	struct xfrm_offload *xo;
33 	struct xfrm_state *x;
34 	__be32 seq;
35 	__be32 spi;
36 	int err;
37 
38 	if (!pskb_pull(skb, offset))
39 		return NULL;
40 
41 	if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
42 		goto out;
43 
44 	xo = xfrm_offload(skb);
45 	if (!xo || !(xo->flags & CRYPTO_DONE)) {
46 		struct sec_path *sp = secpath_set(skb);
47 
48 		if (!sp)
49 			goto out;
50 
51 		if (sp->len == XFRM_MAX_DEPTH)
52 			goto out_reset;
53 
54 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
55 				      (xfrm_address_t *)&ip_hdr(skb)->daddr,
56 				      spi, IPPROTO_ESP, AF_INET);
57 		if (!x)
58 			goto out_reset;
59 
60 		skb->mark = xfrm_smark_get(skb->mark, x);
61 
62 		sp->xvec[sp->len++] = x;
63 		sp->olen++;
64 
65 		xo = xfrm_offload(skb);
66 		if (!xo) {
67 			xfrm_state_put(x);
68 			goto out_reset;
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_reset:
85 	secpath_reset(skb);
86 out:
87 	skb_push(skb, offset);
88 	NAPI_GRO_CB(skb)->same_flow = 0;
89 	NAPI_GRO_CB(skb)->flush = 1;
90 
91 	return NULL;
92 }
93 
94 static void esp4_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
95 {
96 	struct ip_esp_hdr *esph;
97 	struct iphdr *iph = ip_hdr(skb);
98 	struct xfrm_offload *xo = xfrm_offload(skb);
99 	int proto = iph->protocol;
100 
101 	skb_push(skb, -skb_network_offset(skb));
102 	esph = ip_esp_hdr(skb);
103 	*skb_mac_header(skb) = IPPROTO_ESP;
104 
105 	esph->spi = x->id.spi;
106 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
107 
108 	xo->proto = proto;
109 }
110 
111 static struct sk_buff *xfrm4_tunnel_gso_segment(struct xfrm_state *x,
112 						struct sk_buff *skb,
113 						netdev_features_t features)
114 {
115 	__skb_push(skb, skb->mac_len);
116 	return skb_mac_gso_segment(skb, features);
117 }
118 
119 static struct sk_buff *xfrm4_transport_gso_segment(struct xfrm_state *x,
120 						   struct sk_buff *skb,
121 						   netdev_features_t features)
122 {
123 	const struct net_offload *ops;
124 	struct sk_buff *segs = ERR_PTR(-EINVAL);
125 	struct xfrm_offload *xo = xfrm_offload(skb);
126 
127 	skb->transport_header += x->props.header_len;
128 	ops = rcu_dereference(inet_offloads[xo->proto]);
129 	if (likely(ops && ops->callbacks.gso_segment))
130 		segs = ops->callbacks.gso_segment(skb, features);
131 
132 	return segs;
133 }
134 
135 static struct sk_buff *xfrm4_beet_gso_segment(struct xfrm_state *x,
136 					      struct sk_buff *skb,
137 					      netdev_features_t features)
138 {
139 	struct xfrm_offload *xo = xfrm_offload(skb);
140 	struct sk_buff *segs = ERR_PTR(-EINVAL);
141 	const struct net_offload *ops;
142 	int proto = xo->proto;
143 
144 	skb->transport_header += x->props.header_len;
145 
146 	if (proto == IPPROTO_BEETPH) {
147 		struct ip_beet_phdr *ph = (struct ip_beet_phdr *)skb->data;
148 
149 		skb->transport_header += ph->hdrlen * 8;
150 		proto = ph->nexthdr;
151 	} else if (x->sel.family != AF_INET6) {
152 		skb->transport_header -= IPV4_BEET_PHMAXLEN;
153 	} else if (proto == IPPROTO_TCP) {
154 		skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
155 	}
156 
157 	__skb_pull(skb, skb_transport_offset(skb));
158 	ops = rcu_dereference(inet_offloads[proto]);
159 	if (likely(ops && ops->callbacks.gso_segment))
160 		segs = ops->callbacks.gso_segment(skb, features);
161 
162 	return segs;
163 }
164 
165 static struct sk_buff *xfrm4_outer_mode_gso_segment(struct xfrm_state *x,
166 						    struct sk_buff *skb,
167 						    netdev_features_t features)
168 {
169 	switch (x->outer_mode.encap) {
170 	case XFRM_MODE_TUNNEL:
171 		return xfrm4_tunnel_gso_segment(x, skb, features);
172 	case XFRM_MODE_TRANSPORT:
173 		return xfrm4_transport_gso_segment(x, skb, features);
174 	case XFRM_MODE_BEET:
175 		return xfrm4_beet_gso_segment(x, skb, features);
176 	}
177 
178 	return ERR_PTR(-EOPNOTSUPP);
179 }
180 
181 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
182 				        netdev_features_t features)
183 {
184 	struct xfrm_state *x;
185 	struct ip_esp_hdr *esph;
186 	struct crypto_aead *aead;
187 	netdev_features_t esp_features = features;
188 	struct xfrm_offload *xo = xfrm_offload(skb);
189 	struct sec_path *sp;
190 
191 	if (!xo)
192 		return ERR_PTR(-EINVAL);
193 
194 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
195 		return ERR_PTR(-EINVAL);
196 
197 	sp = skb_sec_path(skb);
198 	x = sp->xvec[sp->len - 1];
199 	aead = x->data;
200 	esph = ip_esp_hdr(skb);
201 
202 	if (esph->spi != x->id.spi)
203 		return ERR_PTR(-EINVAL);
204 
205 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
206 		return ERR_PTR(-EINVAL);
207 
208 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
209 
210 	skb->encap_hdr_csum = 1;
211 
212 	if ((!(skb->dev->gso_partial_features & NETIF_F_HW_ESP) &&
213 	     !(features & NETIF_F_HW_ESP)) || x->xso.dev != skb->dev)
214 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
215 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM) &&
216 		 !(skb->dev->gso_partial_features & NETIF_F_HW_ESP_TX_CSUM))
217 		esp_features = features & ~NETIF_F_CSUM_MASK;
218 
219 	xo->flags |= XFRM_GSO_SEGMENT;
220 
221 	return xfrm4_outer_mode_gso_segment(x, skb, esp_features);
222 }
223 
224 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
225 {
226 	struct crypto_aead *aead = x->data;
227 	struct xfrm_offload *xo = xfrm_offload(skb);
228 
229 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
230 		return -EINVAL;
231 
232 	if (!(xo->flags & CRYPTO_DONE))
233 		skb->ip_summed = CHECKSUM_NONE;
234 
235 	return esp_input_done2(skb, 0);
236 }
237 
238 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
239 {
240 	int err;
241 	int alen;
242 	int blksize;
243 	struct xfrm_offload *xo;
244 	struct ip_esp_hdr *esph;
245 	struct crypto_aead *aead;
246 	struct esp_info esp;
247 	bool hw_offload = true;
248 	__u32 seq;
249 
250 	esp.inplace = true;
251 
252 	xo = xfrm_offload(skb);
253 
254 	if (!xo)
255 		return -EINVAL;
256 
257 	if ((!(features & NETIF_F_HW_ESP) &&
258 	     !(skb->dev->gso_partial_features & NETIF_F_HW_ESP)) ||
259 	    x->xso.dev != skb->dev) {
260 		xo->flags |= CRYPTO_FALLBACK;
261 		hw_offload = false;
262 	}
263 
264 	esp.proto = xo->proto;
265 
266 	/* skb is pure payload to encrypt */
267 
268 	aead = x->data;
269 	alen = crypto_aead_authsize(aead);
270 
271 	esp.tfclen = 0;
272 	/* XXX: Add support for tfc padding here. */
273 
274 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
275 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
276 	esp.plen = esp.clen - skb->len - esp.tfclen;
277 	esp.tailen = esp.tfclen + esp.plen + alen;
278 
279 	esp.esph = ip_esp_hdr(skb);
280 
281 
282 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
283 		esp.nfrags = esp_output_head(x, skb, &esp);
284 		if (esp.nfrags < 0)
285 			return esp.nfrags;
286 	}
287 
288 	seq = xo->seq.low;
289 
290 	esph = esp.esph;
291 	esph->spi = x->id.spi;
292 
293 	skb_push(skb, -skb_network_offset(skb));
294 
295 	if (xo->flags & XFRM_GSO_SEGMENT) {
296 		esph->seq_no = htonl(seq);
297 
298 		if (!skb_is_gso(skb))
299 			xo->seq.low++;
300 		else
301 			xo->seq.low += skb_shinfo(skb)->gso_segs;
302 	}
303 
304 	esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
305 
306 	ip_hdr(skb)->tot_len = htons(skb->len);
307 	ip_send_check(ip_hdr(skb));
308 
309 	if (hw_offload)
310 		return 0;
311 
312 	err = esp_output_tail(x, skb, &esp);
313 	if (err)
314 		return err;
315 
316 	secpath_reset(skb);
317 
318 	return 0;
319 }
320 
321 static const struct net_offload esp4_offload = {
322 	.callbacks = {
323 		.gro_receive = esp4_gro_receive,
324 		.gso_segment = esp4_gso_segment,
325 	},
326 };
327 
328 static const struct xfrm_type_offload esp_type_offload = {
329 	.description	= "ESP4 OFFLOAD",
330 	.owner		= THIS_MODULE,
331 	.proto	     	= IPPROTO_ESP,
332 	.input_tail	= esp_input_tail,
333 	.xmit		= esp_xmit,
334 	.encap		= esp4_gso_encap,
335 };
336 
337 static int __init esp4_offload_init(void)
338 {
339 	if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
340 		pr_info("%s: can't add xfrm type offload\n", __func__);
341 		return -EAGAIN;
342 	}
343 
344 	return inet_add_offload(&esp4_offload, IPPROTO_ESP);
345 }
346 
347 static void __exit esp4_offload_exit(void)
348 {
349 	xfrm_unregister_type_offload(&esp_type_offload, AF_INET);
350 	inet_del_offload(&esp4_offload, IPPROTO_ESP);
351 }
352 
353 module_init(esp4_offload_init);
354 module_exit(esp4_offload_exit);
355 MODULE_LICENSE("GPL");
356 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
357 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);
358