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 
esp4_gro_receive(struct list_head * head,struct sk_buff * skb)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 
esp4_gso_encap(struct xfrm_state * x,struct sk_buff * skb)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 
xfrm4_tunnel_gso_segment(struct xfrm_state * x,struct sk_buff * skb,netdev_features_t features)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 	__be16 type = x->inner_mode.family == AF_INET6 ? htons(ETH_P_IPV6)
114 						       : htons(ETH_P_IP);
115 
116 	return skb_eth_gso_segment(skb, features, type);
117 }
118 
xfrm4_transport_gso_segment(struct xfrm_state * x,struct sk_buff * skb,netdev_features_t features)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 
xfrm4_beet_gso_segment(struct xfrm_state * x,struct sk_buff * skb,netdev_features_t features)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 	u8 proto = xo->proto;
143 
144 	skb->transport_header += x->props.header_len;
145 
146 	if (x->sel.family != AF_INET6) {
147 		if (proto == IPPROTO_BEETPH) {
148 			struct ip_beet_phdr *ph =
149 				(struct ip_beet_phdr *)skb->data;
150 
151 			skb->transport_header += ph->hdrlen * 8;
152 			proto = ph->nexthdr;
153 		} else {
154 			skb->transport_header -= IPV4_BEET_PHMAXLEN;
155 		}
156 	} else {
157 		__be16 frag;
158 
159 		skb->transport_header +=
160 			ipv6_skip_exthdr(skb, 0, &proto, &frag);
161 		if (proto == IPPROTO_TCP)
162 			skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
163 	}
164 
165 	if (proto == IPPROTO_IPV6)
166 		skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP4;
167 
168 	__skb_pull(skb, skb_transport_offset(skb));
169 	ops = rcu_dereference(inet_offloads[proto]);
170 	if (likely(ops && ops->callbacks.gso_segment))
171 		segs = ops->callbacks.gso_segment(skb, features);
172 
173 	return segs;
174 }
175 
xfrm4_outer_mode_gso_segment(struct xfrm_state * x,struct sk_buff * skb,netdev_features_t features)176 static struct sk_buff *xfrm4_outer_mode_gso_segment(struct xfrm_state *x,
177 						    struct sk_buff *skb,
178 						    netdev_features_t features)
179 {
180 	switch (x->outer_mode.encap) {
181 	case XFRM_MODE_TUNNEL:
182 		return xfrm4_tunnel_gso_segment(x, skb, features);
183 	case XFRM_MODE_TRANSPORT:
184 		return xfrm4_transport_gso_segment(x, skb, features);
185 	case XFRM_MODE_BEET:
186 		return xfrm4_beet_gso_segment(x, skb, features);
187 	}
188 
189 	return ERR_PTR(-EOPNOTSUPP);
190 }
191 
esp4_gso_segment(struct sk_buff * skb,netdev_features_t features)192 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
193 				        netdev_features_t features)
194 {
195 	struct xfrm_state *x;
196 	struct ip_esp_hdr *esph;
197 	struct crypto_aead *aead;
198 	netdev_features_t esp_features = features;
199 	struct xfrm_offload *xo = xfrm_offload(skb);
200 	struct sec_path *sp;
201 
202 	if (!xo)
203 		return ERR_PTR(-EINVAL);
204 
205 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
206 		return ERR_PTR(-EINVAL);
207 
208 	sp = skb_sec_path(skb);
209 	x = sp->xvec[sp->len - 1];
210 	aead = x->data;
211 	esph = ip_esp_hdr(skb);
212 
213 	if (esph->spi != x->id.spi)
214 		return ERR_PTR(-EINVAL);
215 
216 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
217 		return ERR_PTR(-EINVAL);
218 
219 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
220 
221 	skb->encap_hdr_csum = 1;
222 
223 	if ((!(skb->dev->gso_partial_features & NETIF_F_HW_ESP) &&
224 	     !(features & NETIF_F_HW_ESP)) || x->xso.dev != skb->dev)
225 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK |
226 					    NETIF_F_SCTP_CRC);
227 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM) &&
228 		 !(skb->dev->gso_partial_features & NETIF_F_HW_ESP_TX_CSUM))
229 		esp_features = features & ~(NETIF_F_CSUM_MASK |
230 					    NETIF_F_SCTP_CRC);
231 
232 	xo->flags |= XFRM_GSO_SEGMENT;
233 
234 	return xfrm4_outer_mode_gso_segment(x, skb, esp_features);
235 }
236 
esp_input_tail(struct xfrm_state * x,struct sk_buff * skb)237 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
238 {
239 	struct crypto_aead *aead = x->data;
240 	struct xfrm_offload *xo = xfrm_offload(skb);
241 
242 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
243 		return -EINVAL;
244 
245 	if (!(xo->flags & CRYPTO_DONE))
246 		skb->ip_summed = CHECKSUM_NONE;
247 
248 	return esp_input_done2(skb, 0);
249 }
250 
esp_xmit(struct xfrm_state * x,struct sk_buff * skb,netdev_features_t features)251 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
252 {
253 	int err;
254 	int alen;
255 	int blksize;
256 	struct xfrm_offload *xo;
257 	struct ip_esp_hdr *esph;
258 	struct crypto_aead *aead;
259 	struct esp_info esp;
260 	bool hw_offload = true;
261 	__u32 seq;
262 
263 	esp.inplace = true;
264 
265 	xo = xfrm_offload(skb);
266 
267 	if (!xo)
268 		return -EINVAL;
269 
270 	if ((!(features & NETIF_F_HW_ESP) &&
271 	     !(skb->dev->gso_partial_features & NETIF_F_HW_ESP)) ||
272 	    x->xso.dev != skb->dev) {
273 		xo->flags |= CRYPTO_FALLBACK;
274 		hw_offload = false;
275 	}
276 
277 	esp.proto = xo->proto;
278 
279 	/* skb is pure payload to encrypt */
280 
281 	aead = x->data;
282 	alen = crypto_aead_authsize(aead);
283 
284 	esp.tfclen = 0;
285 	/* XXX: Add support for tfc padding here. */
286 
287 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
288 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
289 	esp.plen = esp.clen - skb->len - esp.tfclen;
290 	esp.tailen = esp.tfclen + esp.plen + alen;
291 
292 	esp.esph = ip_esp_hdr(skb);
293 
294 
295 	if (!hw_offload || !skb_is_gso(skb)) {
296 		esp.nfrags = esp_output_head(x, skb, &esp);
297 		if (esp.nfrags < 0)
298 			return esp.nfrags;
299 	}
300 
301 	seq = xo->seq.low;
302 
303 	esph = esp.esph;
304 	esph->spi = x->id.spi;
305 
306 	skb_push(skb, -skb_network_offset(skb));
307 
308 	if (xo->flags & XFRM_GSO_SEGMENT) {
309 		esph->seq_no = htonl(seq);
310 
311 		if (!skb_is_gso(skb))
312 			xo->seq.low++;
313 		else
314 			xo->seq.low += skb_shinfo(skb)->gso_segs;
315 	}
316 
317 	if (xo->seq.low < seq)
318 		xo->seq.hi++;
319 
320 	esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
321 
322 	ip_hdr(skb)->tot_len = htons(skb->len);
323 	ip_send_check(ip_hdr(skb));
324 
325 	if (hw_offload) {
326 		if (!skb_ext_add(skb, SKB_EXT_SEC_PATH))
327 			return -ENOMEM;
328 
329 		xo = xfrm_offload(skb);
330 		if (!xo)
331 			return -EINVAL;
332 
333 		xo->flags |= XFRM_XMIT;
334 		return 0;
335 	}
336 
337 	err = esp_output_tail(x, skb, &esp);
338 	if (err)
339 		return err;
340 
341 	secpath_reset(skb);
342 
343 	return 0;
344 }
345 
346 static const struct net_offload esp4_offload = {
347 	.callbacks = {
348 		.gro_receive = esp4_gro_receive,
349 		.gso_segment = esp4_gso_segment,
350 	},
351 };
352 
353 static const struct xfrm_type_offload esp_type_offload = {
354 	.owner		= THIS_MODULE,
355 	.proto	     	= IPPROTO_ESP,
356 	.input_tail	= esp_input_tail,
357 	.xmit		= esp_xmit,
358 	.encap		= esp4_gso_encap,
359 };
360 
esp4_offload_init(void)361 static int __init esp4_offload_init(void)
362 {
363 	if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
364 		pr_info("%s: can't add xfrm type offload\n", __func__);
365 		return -EAGAIN;
366 	}
367 
368 	return inet_add_offload(&esp4_offload, IPPROTO_ESP);
369 }
370 
esp4_offload_exit(void)371 static void __exit esp4_offload_exit(void)
372 {
373 	xfrm_unregister_type_offload(&esp_type_offload, AF_INET);
374 	inet_del_offload(&esp4_offload, IPPROTO_ESP);
375 }
376 
377 module_init(esp4_offload_init);
378 module_exit(esp4_offload_exit);
379 MODULE_LICENSE("GPL");
380 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
381 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);
382 MODULE_DESCRIPTION("IPV4 GSO/GRO offload support");
383