xref: /linux/net/ipv4/esp4_offload.c (revision 0be3ff0c) 
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/gro.h>
20 #include <net/ip.h>
21 #include <net/xfrm.h>
22 #include <net/esp.h>
23 #include <linux/scatterlist.h>
24 #include <linux/kernel.h>
25 #include <linux/slab.h>
26 #include <linux/spinlock.h>
27 #include <net/udp.h>
28 
29 static struct sk_buff *esp4_gro_receive(struct list_head *head,
30 					struct sk_buff *skb)
31 {
32 	int offset = skb_gro_offset(skb);
33 	struct xfrm_offload *xo;
34 	struct xfrm_state *x;
35 	__be32 seq;
36 	__be32 spi;
37 
38 	if (!pskb_pull(skb, offset))
39 		return NULL;
40 
41 	if (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 			goto out_reset;
68 	}
69 
70 	xo->flags |= XFRM_GRO;
71 
72 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
73 	XFRM_SPI_SKB_CB(skb)->family = AF_INET;
74 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
75 	XFRM_SPI_SKB_CB(skb)->seq = seq;
76 
77 	/* We don't need to handle errors from xfrm_input, it does all
78 	 * the error handling and frees the resources on error. */
79 	xfrm_input(skb, IPPROTO_ESP, spi, -2);
80 
81 	return ERR_PTR(-EINPROGRESS);
82 out_reset:
83 	secpath_reset(skb);
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 *xfrm4_tunnel_gso_segment(struct xfrm_state *x,
110 						struct sk_buff *skb,
111 						netdev_features_t features)
112 {
113 	return skb_eth_gso_segment(skb, features, htons(ETH_P_IP));
114 }
115 
116 static struct sk_buff *xfrm4_transport_gso_segment(struct xfrm_state *x,
117 						   struct sk_buff *skb,
118 						   netdev_features_t features)
119 {
120 	const struct net_offload *ops;
121 	struct sk_buff *segs = ERR_PTR(-EINVAL);
122 	struct xfrm_offload *xo = xfrm_offload(skb);
123 
124 	skb->transport_header += x->props.header_len;
125 	ops = rcu_dereference(inet_offloads[xo->proto]);
126 	if (likely(ops && ops->callbacks.gso_segment))
127 		segs = ops->callbacks.gso_segment(skb, features);
128 
129 	return segs;
130 }
131 
132 static struct sk_buff *xfrm4_beet_gso_segment(struct xfrm_state *x,
133 					      struct sk_buff *skb,
134 					      netdev_features_t features)
135 {
136 	struct xfrm_offload *xo = xfrm_offload(skb);
137 	struct sk_buff *segs = ERR_PTR(-EINVAL);
138 	const struct net_offload *ops;
139 	u8 proto = xo->proto;
140 
141 	skb->transport_header += x->props.header_len;
142 
143 	if (x->sel.family != AF_INET6) {
144 		if (proto == IPPROTO_BEETPH) {
145 			struct ip_beet_phdr *ph =
146 				(struct ip_beet_phdr *)skb->data;
147 
148 			skb->transport_header += ph->hdrlen * 8;
149 			proto = ph->nexthdr;
150 		} else {
151 			skb->transport_header -= IPV4_BEET_PHMAXLEN;
152 		}
153 	} else {
154 		__be16 frag;
155 
156 		skb->transport_header +=
157 			ipv6_skip_exthdr(skb, 0, &proto, &frag);
158 		if (proto == IPPROTO_TCP)
159 			skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
160 	}
161 
162 	if (proto == IPPROTO_IPV6)
163 		skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP4;
164 
165 	__skb_pull(skb, skb_transport_offset(skb));
166 	ops = rcu_dereference(inet_offloads[proto]);
167 	if (likely(ops && ops->callbacks.gso_segment))
168 		segs = ops->callbacks.gso_segment(skb, features);
169 
170 	return segs;
171 }
172 
173 static struct sk_buff *xfrm4_outer_mode_gso_segment(struct xfrm_state *x,
174 						    struct sk_buff *skb,
175 						    netdev_features_t features)
176 {
177 	switch (x->outer_mode.encap) {
178 	case XFRM_MODE_TUNNEL:
179 		return xfrm4_tunnel_gso_segment(x, skb, features);
180 	case XFRM_MODE_TRANSPORT:
181 		return xfrm4_transport_gso_segment(x, skb, features);
182 	case XFRM_MODE_BEET:
183 		return xfrm4_beet_gso_segment(x, skb, features);
184 	}
185 
186 	return ERR_PTR(-EOPNOTSUPP);
187 }
188 
189 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
190 				        netdev_features_t features)
191 {
192 	struct xfrm_state *x;
193 	struct ip_esp_hdr *esph;
194 	struct crypto_aead *aead;
195 	netdev_features_t esp_features = features;
196 	struct xfrm_offload *xo = xfrm_offload(skb);
197 	struct sec_path *sp;
198 
199 	if (!xo)
200 		return ERR_PTR(-EINVAL);
201 
202 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
203 		return ERR_PTR(-EINVAL);
204 
205 	sp = skb_sec_path(skb);
206 	x = sp->xvec[sp->len - 1];
207 	aead = x->data;
208 	esph = ip_esp_hdr(skb);
209 
210 	if (esph->spi != x->id.spi)
211 		return ERR_PTR(-EINVAL);
212 
213 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
214 		return ERR_PTR(-EINVAL);
215 
216 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
217 
218 	skb->encap_hdr_csum = 1;
219 
220 	if ((!(skb->dev->gso_partial_features & NETIF_F_HW_ESP) &&
221 	     !(features & NETIF_F_HW_ESP)) || x->xso.dev != skb->dev)
222 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK |
223 					    NETIF_F_SCTP_CRC);
224 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM) &&
225 		 !(skb->dev->gso_partial_features & NETIF_F_HW_ESP_TX_CSUM))
226 		esp_features = features & ~(NETIF_F_CSUM_MASK |
227 					    NETIF_F_SCTP_CRC);
228 
229 	xo->flags |= XFRM_GSO_SEGMENT;
230 
231 	return xfrm4_outer_mode_gso_segment(x, skb, esp_features);
232 }
233 
234 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
235 {
236 	struct crypto_aead *aead = x->data;
237 	struct xfrm_offload *xo = xfrm_offload(skb);
238 
239 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
240 		return -EINVAL;
241 
242 	if (!(xo->flags & CRYPTO_DONE))
243 		skb->ip_summed = CHECKSUM_NONE;
244 
245 	return esp_input_done2(skb, 0);
246 }
247 
248 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
249 {
250 	int err;
251 	int alen;
252 	int blksize;
253 	struct xfrm_offload *xo;
254 	struct ip_esp_hdr *esph;
255 	struct crypto_aead *aead;
256 	struct esp_info esp;
257 	bool hw_offload = true;
258 	__u32 seq;
259 
260 	esp.inplace = true;
261 
262 	xo = xfrm_offload(skb);
263 
264 	if (!xo)
265 		return -EINVAL;
266 
267 	if ((!(features & NETIF_F_HW_ESP) &&
268 	     !(skb->dev->gso_partial_features & NETIF_F_HW_ESP)) ||
269 	    x->xso.dev != skb->dev) {
270 		xo->flags |= CRYPTO_FALLBACK;
271 		hw_offload = false;
272 	}
273 
274 	esp.proto = xo->proto;
275 
276 	/* skb is pure payload to encrypt */
277 
278 	aead = x->data;
279 	alen = crypto_aead_authsize(aead);
280 
281 	esp.tfclen = 0;
282 	/* XXX: Add support for tfc padding here. */
283 
284 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
285 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
286 	esp.plen = esp.clen - skb->len - esp.tfclen;
287 	esp.tailen = esp.tfclen + esp.plen + alen;
288 
289 	esp.esph = ip_esp_hdr(skb);
290 
291 
292 	if (!hw_offload || !skb_is_gso(skb)) {
293 		esp.nfrags = esp_output_head(x, skb, &esp);
294 		if (esp.nfrags < 0)
295 			return esp.nfrags;
296 	}
297 
298 	seq = xo->seq.low;
299 
300 	esph = esp.esph;
301 	esph->spi = x->id.spi;
302 
303 	skb_push(skb, -skb_network_offset(skb));
304 
305 	if (xo->flags & XFRM_GSO_SEGMENT) {
306 		esph->seq_no = htonl(seq);
307 
308 		if (!skb_is_gso(skb))
309 			xo->seq.low++;
310 		else
311 			xo->seq.low += skb_shinfo(skb)->gso_segs;
312 	}
313 
314 	esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
315 
316 	ip_hdr(skb)->tot_len = htons(skb->len);
317 	ip_send_check(ip_hdr(skb));
318 
319 	if (hw_offload) {
320 		if (!skb_ext_add(skb, SKB_EXT_SEC_PATH))
321 			return -ENOMEM;
322 
323 		xo = xfrm_offload(skb);
324 		if (!xo)
325 			return -EINVAL;
326 
327 		xo->flags |= XFRM_XMIT;
328 		return 0;
329 	}
330 
331 	err = esp_output_tail(x, skb, &esp);
332 	if (err)
333 		return err;
334 
335 	secpath_reset(skb);
336 
337 	return 0;
338 }
339 
340 static const struct net_offload esp4_offload = {
341 	.callbacks = {
342 		.gro_receive = esp4_gro_receive,
343 		.gso_segment = esp4_gso_segment,
344 	},
345 };
346 
347 static const struct xfrm_type_offload esp_type_offload = {
348 	.owner		= THIS_MODULE,
349 	.proto	     	= IPPROTO_ESP,
350 	.input_tail	= esp_input_tail,
351 	.xmit		= esp_xmit,
352 	.encap		= esp4_gso_encap,
353 };
354 
355 static int __init esp4_offload_init(void)
356 {
357 	if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
358 		pr_info("%s: can't add xfrm type offload\n", __func__);
359 		return -EAGAIN;
360 	}
361 
362 	return inet_add_offload(&esp4_offload, IPPROTO_ESP);
363 }
364 
365 static void __exit esp4_offload_exit(void)
366 {
367 	xfrm_unregister_type_offload(&esp_type_offload, AF_INET);
368 	inet_del_offload(&esp4_offload, IPPROTO_ESP);
369 }
370 
371 module_init(esp4_offload_init);
372 module_exit(esp4_offload_exit);
373 MODULE_LICENSE("GPL");
374 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
375 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);
376 MODULE_DESCRIPTION("IPV4 GSO/GRO offload support");
377