xref: /openbmc/linux/net/ipv4/esp4_offload.c (revision 7f877908) 
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_outer_mode_gso_segment(struct xfrm_state *x,
136 						    struct sk_buff *skb,
137 						    netdev_features_t features)
138 {
139 	switch (x->outer_mode.encap) {
140 	case XFRM_MODE_TUNNEL:
141 		return xfrm4_tunnel_gso_segment(x, skb, features);
142 	case XFRM_MODE_TRANSPORT:
143 		return xfrm4_transport_gso_segment(x, skb, features);
144 	}
145 
146 	return ERR_PTR(-EOPNOTSUPP);
147 }
148 
149 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
150 				        netdev_features_t features)
151 {
152 	struct xfrm_state *x;
153 	struct ip_esp_hdr *esph;
154 	struct crypto_aead *aead;
155 	netdev_features_t esp_features = features;
156 	struct xfrm_offload *xo = xfrm_offload(skb);
157 	struct sec_path *sp;
158 
159 	if (!xo)
160 		return ERR_PTR(-EINVAL);
161 
162 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
163 		return ERR_PTR(-EINVAL);
164 
165 	sp = skb_sec_path(skb);
166 	x = sp->xvec[sp->len - 1];
167 	aead = x->data;
168 	esph = ip_esp_hdr(skb);
169 
170 	if (esph->spi != x->id.spi)
171 		return ERR_PTR(-EINVAL);
172 
173 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
174 		return ERR_PTR(-EINVAL);
175 
176 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
177 
178 	skb->encap_hdr_csum = 1;
179 
180 	if ((!(skb->dev->gso_partial_features & NETIF_F_HW_ESP) &&
181 	     !(features & NETIF_F_HW_ESP)) || x->xso.dev != skb->dev)
182 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
183 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM) &&
184 		 !(skb->dev->gso_partial_features & NETIF_F_HW_ESP_TX_CSUM))
185 		esp_features = features & ~NETIF_F_CSUM_MASK;
186 
187 	xo->flags |= XFRM_GSO_SEGMENT;
188 
189 	return xfrm4_outer_mode_gso_segment(x, skb, esp_features);
190 }
191 
192 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
193 {
194 	struct crypto_aead *aead = x->data;
195 	struct xfrm_offload *xo = xfrm_offload(skb);
196 
197 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
198 		return -EINVAL;
199 
200 	if (!(xo->flags & CRYPTO_DONE))
201 		skb->ip_summed = CHECKSUM_NONE;
202 
203 	return esp_input_done2(skb, 0);
204 }
205 
206 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
207 {
208 	int err;
209 	int alen;
210 	int blksize;
211 	struct xfrm_offload *xo;
212 	struct ip_esp_hdr *esph;
213 	struct crypto_aead *aead;
214 	struct esp_info esp;
215 	bool hw_offload = true;
216 	__u32 seq;
217 
218 	esp.inplace = true;
219 
220 	xo = xfrm_offload(skb);
221 
222 	if (!xo)
223 		return -EINVAL;
224 
225 	if ((!(features & NETIF_F_HW_ESP) &&
226 	     !(skb->dev->gso_partial_features & NETIF_F_HW_ESP)) ||
227 	    x->xso.dev != skb->dev) {
228 		xo->flags |= CRYPTO_FALLBACK;
229 		hw_offload = false;
230 	}
231 
232 	esp.proto = xo->proto;
233 
234 	/* skb is pure payload to encrypt */
235 
236 	aead = x->data;
237 	alen = crypto_aead_authsize(aead);
238 
239 	esp.tfclen = 0;
240 	/* XXX: Add support for tfc padding here. */
241 
242 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
243 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
244 	esp.plen = esp.clen - skb->len - esp.tfclen;
245 	esp.tailen = esp.tfclen + esp.plen + alen;
246 
247 	esp.esph = ip_esp_hdr(skb);
248 
249 
250 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
251 		esp.nfrags = esp_output_head(x, skb, &esp);
252 		if (esp.nfrags < 0)
253 			return esp.nfrags;
254 	}
255 
256 	seq = xo->seq.low;
257 
258 	esph = esp.esph;
259 	esph->spi = x->id.spi;
260 
261 	skb_push(skb, -skb_network_offset(skb));
262 
263 	if (xo->flags & XFRM_GSO_SEGMENT) {
264 		esph->seq_no = htonl(seq);
265 
266 		if (!skb_is_gso(skb))
267 			xo->seq.low++;
268 		else
269 			xo->seq.low += skb_shinfo(skb)->gso_segs;
270 	}
271 
272 	esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
273 
274 	ip_hdr(skb)->tot_len = htons(skb->len);
275 	ip_send_check(ip_hdr(skb));
276 
277 	if (hw_offload)
278 		return 0;
279 
280 	err = esp_output_tail(x, skb, &esp);
281 	if (err)
282 		return err;
283 
284 	secpath_reset(skb);
285 
286 	return 0;
287 }
288 
289 static const struct net_offload esp4_offload = {
290 	.callbacks = {
291 		.gro_receive = esp4_gro_receive,
292 		.gso_segment = esp4_gso_segment,
293 	},
294 };
295 
296 static const struct xfrm_type_offload esp_type_offload = {
297 	.description	= "ESP4 OFFLOAD",
298 	.owner		= THIS_MODULE,
299 	.proto	     	= IPPROTO_ESP,
300 	.input_tail	= esp_input_tail,
301 	.xmit		= esp_xmit,
302 	.encap		= esp4_gso_encap,
303 };
304 
305 static int __init esp4_offload_init(void)
306 {
307 	if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
308 		pr_info("%s: can't add xfrm type offload\n", __func__);
309 		return -EAGAIN;
310 	}
311 
312 	return inet_add_offload(&esp4_offload, IPPROTO_ESP);
313 }
314 
315 static void __exit esp4_offload_exit(void)
316 {
317 	xfrm_unregister_type_offload(&esp_type_offload, AF_INET);
318 	inet_del_offload(&esp4_offload, IPPROTO_ESP);
319 }
320 
321 module_init(esp4_offload_init);
322 module_exit(esp4_offload_exit);
323 MODULE_LICENSE("GPL");
324 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
325 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);
326