xref: /linux/net/ipv4/esp4_offload.c (revision 7f71507851fc7764b36a3221839607d3a45c2025) 
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/gso.h>
21 #include <net/ip.h>
22 #include <net/xfrm.h>
23 #include <net/esp.h>
24 #include <linux/scatterlist.h>
25 #include <linux/kernel.h>
26 #include <linux/slab.h>
27 #include <linux/spinlock.h>
28 #include <net/udp.h>
29 
30 static struct sk_buff *esp4_gro_receive(struct list_head *head,
31 					struct sk_buff *skb)
32 {
33 	int offset = skb_gro_offset(skb);
34 	struct xfrm_offload *xo;
35 	struct xfrm_state *x;
36 	int encap_type = 0;
37 	__be32 seq;
38 	__be32 spi;
39 
40 	if (!pskb_pull(skb, offset))
41 		return NULL;
42 
43 	if (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 		struct sec_path *sp = secpath_set(skb);
49 
50 		if (!sp)
51 			goto out;
52 
53 		if (sp->len == XFRM_MAX_DEPTH)
54 			goto out_reset;
55 
56 		x = xfrm_input_state_lookup(dev_net(skb->dev), skb->mark,
57 					    (xfrm_address_t *)&ip_hdr(skb)->daddr,
58 					    spi, IPPROTO_ESP, AF_INET);
59 
60 		if (unlikely(x && x->dir && x->dir != XFRM_SA_DIR_IN)) {
61 			/* non-offload path will record the error and audit log */
62 			xfrm_state_put(x);
63 			x = NULL;
64 		}
65 
66 		if (!x)
67 			goto out_reset;
68 
69 		skb->mark = xfrm_smark_get(skb->mark, x);
70 
71 		sp->xvec[sp->len++] = x;
72 		sp->olen++;
73 
74 		xo = xfrm_offload(skb);
75 		if (!xo)
76 			goto out_reset;
77 	}
78 
79 	xo->flags |= XFRM_GRO;
80 
81 	if (NAPI_GRO_CB(skb)->proto == IPPROTO_UDP)
82 		encap_type = UDP_ENCAP_ESPINUDP;
83 
84 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
85 	XFRM_SPI_SKB_CB(skb)->family = AF_INET;
86 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
87 	XFRM_SPI_SKB_CB(skb)->seq = seq;
88 
89 	/* We don't need to handle errors from xfrm_input, it does all
90 	 * the error handling and frees the resources on error. */
91 	xfrm_input(skb, IPPROTO_ESP, spi, encap_type);
92 
93 	return ERR_PTR(-EINPROGRESS);
94 out_reset:
95 	secpath_reset(skb);
96 out:
97 	skb_push(skb, offset);
98 	NAPI_GRO_CB(skb)->same_flow = 0;
99 	NAPI_GRO_CB(skb)->flush = 1;
100 
101 	return NULL;
102 }
103 
104 static void esp4_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
105 {
106 	struct ip_esp_hdr *esph;
107 	struct iphdr *iph = ip_hdr(skb);
108 	struct xfrm_offload *xo = xfrm_offload(skb);
109 	int proto = iph->protocol;
110 
111 	skb_push(skb, -skb_network_offset(skb));
112 	esph = ip_esp_hdr(skb);
113 	*skb_mac_header(skb) = IPPROTO_ESP;
114 
115 	esph->spi = x->id.spi;
116 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
117 
118 	xo->proto = proto;
119 }
120 
121 static struct sk_buff *xfrm4_tunnel_gso_segment(struct xfrm_state *x,
122 						struct sk_buff *skb,
123 						netdev_features_t features)
124 {
125 	__be16 type = x->inner_mode.family == AF_INET6 ? htons(ETH_P_IPV6)
126 						       : htons(ETH_P_IP);
127 
128 	return skb_eth_gso_segment(skb, features, type);
129 }
130 
131 static struct sk_buff *xfrm4_transport_gso_segment(struct xfrm_state *x,
132 						   struct sk_buff *skb,
133 						   netdev_features_t features)
134 {
135 	const struct net_offload *ops;
136 	struct sk_buff *segs = ERR_PTR(-EINVAL);
137 	struct xfrm_offload *xo = xfrm_offload(skb);
138 
139 	skb->transport_header += x->props.header_len;
140 	ops = rcu_dereference(inet_offloads[xo->proto]);
141 	if (likely(ops && ops->callbacks.gso_segment))
142 		segs = ops->callbacks.gso_segment(skb, features);
143 
144 	return segs;
145 }
146 
147 static struct sk_buff *xfrm4_beet_gso_segment(struct xfrm_state *x,
148 					      struct sk_buff *skb,
149 					      netdev_features_t features)
150 {
151 	struct xfrm_offload *xo = xfrm_offload(skb);
152 	struct sk_buff *segs = ERR_PTR(-EINVAL);
153 	const struct net_offload *ops;
154 	u8 proto = xo->proto;
155 
156 	skb->transport_header += x->props.header_len;
157 
158 	if (x->sel.family != AF_INET6) {
159 		if (proto == IPPROTO_BEETPH) {
160 			struct ip_beet_phdr *ph =
161 				(struct ip_beet_phdr *)skb->data;
162 
163 			skb->transport_header += ph->hdrlen * 8;
164 			proto = ph->nexthdr;
165 		} else {
166 			skb->transport_header -= IPV4_BEET_PHMAXLEN;
167 		}
168 	} else {
169 		__be16 frag;
170 
171 		skb->transport_header +=
172 			ipv6_skip_exthdr(skb, 0, &proto, &frag);
173 		if (proto == IPPROTO_TCP)
174 			skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
175 	}
176 
177 	if (proto == IPPROTO_IPV6)
178 		skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP4;
179 
180 	__skb_pull(skb, skb_transport_offset(skb));
181 	ops = rcu_dereference(inet_offloads[proto]);
182 	if (likely(ops && ops->callbacks.gso_segment))
183 		segs = ops->callbacks.gso_segment(skb, features);
184 
185 	return segs;
186 }
187 
188 static struct sk_buff *xfrm4_outer_mode_gso_segment(struct xfrm_state *x,
189 						    struct sk_buff *skb,
190 						    netdev_features_t features)
191 {
192 	switch (x->outer_mode.encap) {
193 	case XFRM_MODE_TUNNEL:
194 		return xfrm4_tunnel_gso_segment(x, skb, features);
195 	case XFRM_MODE_TRANSPORT:
196 		return xfrm4_transport_gso_segment(x, skb, features);
197 	case XFRM_MODE_BEET:
198 		return xfrm4_beet_gso_segment(x, skb, features);
199 	}
200 
201 	return ERR_PTR(-EOPNOTSUPP);
202 }
203 
204 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
205 				        netdev_features_t features)
206 {
207 	struct xfrm_state *x;
208 	struct ip_esp_hdr *esph;
209 	struct crypto_aead *aead;
210 	netdev_features_t esp_features = features;
211 	struct xfrm_offload *xo = xfrm_offload(skb);
212 	struct sec_path *sp;
213 
214 	if (!xo)
215 		return ERR_PTR(-EINVAL);
216 
217 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
218 		return ERR_PTR(-EINVAL);
219 
220 	sp = skb_sec_path(skb);
221 	x = sp->xvec[sp->len - 1];
222 	aead = x->data;
223 	esph = ip_esp_hdr(skb);
224 
225 	if (esph->spi != x->id.spi)
226 		return ERR_PTR(-EINVAL);
227 
228 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
229 		return ERR_PTR(-EINVAL);
230 
231 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
232 
233 	skb->encap_hdr_csum = 1;
234 
235 	if ((!(skb->dev->gso_partial_features & NETIF_F_HW_ESP) &&
236 	     !(features & NETIF_F_HW_ESP)) || x->xso.dev != skb->dev)
237 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK |
238 					    NETIF_F_SCTP_CRC);
239 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM) &&
240 		 !(skb->dev->gso_partial_features & NETIF_F_HW_ESP_TX_CSUM))
241 		esp_features = features & ~(NETIF_F_CSUM_MASK |
242 					    NETIF_F_SCTP_CRC);
243 
244 	xo->flags |= XFRM_GSO_SEGMENT;
245 
246 	return xfrm4_outer_mode_gso_segment(x, skb, esp_features);
247 }
248 
249 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
250 {
251 	struct crypto_aead *aead = x->data;
252 	struct xfrm_offload *xo = xfrm_offload(skb);
253 
254 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
255 		return -EINVAL;
256 
257 	if (!(xo->flags & CRYPTO_DONE))
258 		skb->ip_summed = CHECKSUM_NONE;
259 
260 	return esp_input_done2(skb, 0);
261 }
262 
263 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
264 {
265 	int err;
266 	int alen;
267 	int blksize;
268 	struct xfrm_offload *xo;
269 	struct ip_esp_hdr *esph;
270 	struct crypto_aead *aead;
271 	struct esp_info esp;
272 	bool hw_offload = true;
273 	__u32 seq;
274 	int encap_type = 0;
275 
276 	esp.inplace = true;
277 
278 	xo = xfrm_offload(skb);
279 
280 	if (!xo)
281 		return -EINVAL;
282 
283 	if ((!(features & NETIF_F_HW_ESP) &&
284 	     !(skb->dev->gso_partial_features & NETIF_F_HW_ESP)) ||
285 	    x->xso.dev != skb->dev) {
286 		xo->flags |= CRYPTO_FALLBACK;
287 		hw_offload = false;
288 	}
289 
290 	esp.proto = xo->proto;
291 
292 	/* skb is pure payload to encrypt */
293 
294 	aead = x->data;
295 	alen = crypto_aead_authsize(aead);
296 
297 	esp.tfclen = 0;
298 	/* XXX: Add support for tfc padding here. */
299 
300 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
301 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
302 	esp.plen = esp.clen - skb->len - esp.tfclen;
303 	esp.tailen = esp.tfclen + esp.plen + alen;
304 
305 	esp.esph = ip_esp_hdr(skb);
306 
307 	if (x->encap)
308 		encap_type = x->encap->encap_type;
309 
310 	if (!hw_offload || !skb_is_gso(skb) || (hw_offload && encap_type == UDP_ENCAP_ESPINUDP)) {
311 		esp.nfrags = esp_output_head(x, skb, &esp);
312 		if (esp.nfrags < 0)
313 			return esp.nfrags;
314 	}
315 
316 	seq = xo->seq.low;
317 
318 	esph = esp.esph;
319 	esph->spi = x->id.spi;
320 
321 	skb_push(skb, -skb_network_offset(skb));
322 
323 	if (xo->flags & XFRM_GSO_SEGMENT) {
324 		esph->seq_no = htonl(seq);
325 
326 		if (!skb_is_gso(skb))
327 			xo->seq.low++;
328 		else
329 			xo->seq.low += skb_shinfo(skb)->gso_segs;
330 	}
331 
332 	if (xo->seq.low < seq)
333 		xo->seq.hi++;
334 
335 	esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
336 
337 	if (hw_offload && encap_type == UDP_ENCAP_ESPINUDP) {
338 		/* In the XFRM stack, the encapsulation protocol is set to iphdr->protocol by
339 		 * setting *skb_mac_header(skb) (see esp_output_udp_encap()) where skb->mac_header
340 		 * points to iphdr->protocol (see xfrm4_tunnel_encap_add()).
341 		 * However, in esp_xmit(), skb->mac_header doesn't point to iphdr->protocol.
342 		 * Therefore, the protocol field needs to be corrected.
343 		 */
344 		ip_hdr(skb)->protocol = IPPROTO_UDP;
345 
346 		esph->seq_no = htonl(seq);
347 	}
348 
349 	ip_hdr(skb)->tot_len = htons(skb->len);
350 	ip_send_check(ip_hdr(skb));
351 
352 	if (hw_offload) {
353 		if (!skb_ext_add(skb, SKB_EXT_SEC_PATH))
354 			return -ENOMEM;
355 
356 		xo = xfrm_offload(skb);
357 		if (!xo)
358 			return -EINVAL;
359 
360 		xo->flags |= XFRM_XMIT;
361 		return 0;
362 	}
363 
364 	err = esp_output_tail(x, skb, &esp);
365 	if (err)
366 		return err;
367 
368 	secpath_reset(skb);
369 
370 	if (skb_needs_linearize(skb, skb->dev->features) &&
371 	    __skb_linearize(skb))
372 		return -ENOMEM;
373 	return 0;
374 }
375 
376 static const struct net_offload esp4_offload = {
377 	.callbacks = {
378 		.gro_receive = esp4_gro_receive,
379 		.gso_segment = esp4_gso_segment,
380 	},
381 };
382 
383 static const struct xfrm_type_offload esp_type_offload = {
384 	.owner		= THIS_MODULE,
385 	.proto	     	= IPPROTO_ESP,
386 	.input_tail	= esp_input_tail,
387 	.xmit		= esp_xmit,
388 	.encap		= esp4_gso_encap,
389 };
390 
391 static int __init esp4_offload_init(void)
392 {
393 	if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
394 		pr_info("%s: can't add xfrm type offload\n", __func__);
395 		return -EAGAIN;
396 	}
397 
398 	return inet_add_offload(&esp4_offload, IPPROTO_ESP);
399 }
400 
401 static void __exit esp4_offload_exit(void)
402 {
403 	xfrm_unregister_type_offload(&esp_type_offload, AF_INET);
404 	inet_del_offload(&esp4_offload, IPPROTO_ESP);
405 }
406 
407 module_init(esp4_offload_init);
408 module_exit(esp4_offload_exit);
409 MODULE_LICENSE("GPL");
410 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
411 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);
412 MODULE_DESCRIPTION("IPV4 GSO/GRO offload support");
413