xref: /openbmc/linux/net/ipv4/esp4_offload.c (revision 8f8d5745bb520c76b81abef4a2cb3023d0313bfd) 
1 /*
2  * IPV4 GSO/GRO offload support
3  * Linux INET implementation
4  *
5  * Copyright (C) 2016 secunet Security Networks AG
6  * Author: Steffen Klassert <steffen.klassert@secunet.com>
7  *
8  * This program is free software; you can redistribute it and/or modify it
9  * under the terms and conditions of the GNU General Public License,
10  * version 2, as published by the Free Software Foundation.
11  *
12  * ESP GRO support
13  */
14 
15 #include <linux/skbuff.h>
16 #include <linux/init.h>
17 #include <net/protocol.h>
18 #include <crypto/aead.h>
19 #include <crypto/authenc.h>
20 #include <linux/err.h>
21 #include <linux/module.h>
22 #include <net/ip.h>
23 #include <net/xfrm.h>
24 #include <net/esp.h>
25 #include <linux/scatterlist.h>
26 #include <linux/kernel.h>
27 #include <linux/slab.h>
28 #include <linux/spinlock.h>
29 #include <net/udp.h>
30 
31 static struct sk_buff *esp4_gro_receive(struct list_head *head,
32 					struct sk_buff *skb)
33 {
34 	int offset = skb_gro_offset(skb);
35 	struct xfrm_offload *xo;
36 	struct xfrm_state *x;
37 	__be32 seq;
38 	__be32 spi;
39 	int err;
40 
41 	if (!pskb_pull(skb, offset))
42 		return NULL;
43 
44 	if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
45 		goto out;
46 
47 	xo = xfrm_offload(skb);
48 	if (!xo || !(xo->flags & CRYPTO_DONE)) {
49 		struct sec_path *sp = secpath_set(skb);
50 
51 		if (!sp)
52 			goto out;
53 
54 		if (sp->len == XFRM_MAX_DEPTH)
55 			goto out_reset;
56 
57 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
58 				      (xfrm_address_t *)&ip_hdr(skb)->daddr,
59 				      spi, IPPROTO_ESP, AF_INET);
60 		if (!x)
61 			goto out_reset;
62 
63 		sp->xvec[sp->len++] = x;
64 		sp->olen++;
65 
66 		xo = xfrm_offload(skb);
67 		if (!xo) {
68 			xfrm_state_put(x);
69 			goto out_reset;
70 		}
71 	}
72 
73 	xo->flags |= XFRM_GRO;
74 
75 	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
76 	XFRM_SPI_SKB_CB(skb)->family = AF_INET;
77 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
78 	XFRM_SPI_SKB_CB(skb)->seq = seq;
79 
80 	/* We don't need to handle errors from xfrm_input, it does all
81 	 * the error handling and frees the resources on error. */
82 	xfrm_input(skb, IPPROTO_ESP, spi, -2);
83 
84 	return ERR_PTR(-EINPROGRESS);
85 out_reset:
86 	secpath_reset(skb);
87 out:
88 	skb_push(skb, offset);
89 	NAPI_GRO_CB(skb)->same_flow = 0;
90 	NAPI_GRO_CB(skb)->flush = 1;
91 
92 	return NULL;
93 }
94 
95 static void esp4_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
96 {
97 	struct ip_esp_hdr *esph;
98 	struct iphdr *iph = ip_hdr(skb);
99 	struct xfrm_offload *xo = xfrm_offload(skb);
100 	int proto = iph->protocol;
101 
102 	skb_push(skb, -skb_network_offset(skb));
103 	esph = ip_esp_hdr(skb);
104 	*skb_mac_header(skb) = IPPROTO_ESP;
105 
106 	esph->spi = x->id.spi;
107 	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
108 
109 	xo->proto = proto;
110 }
111 
112 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
113 				        netdev_features_t features)
114 {
115 	struct xfrm_state *x;
116 	struct ip_esp_hdr *esph;
117 	struct crypto_aead *aead;
118 	netdev_features_t esp_features = features;
119 	struct xfrm_offload *xo = xfrm_offload(skb);
120 	struct sec_path *sp;
121 
122 	if (!xo)
123 		return ERR_PTR(-EINVAL);
124 
125 	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
126 		return ERR_PTR(-EINVAL);
127 
128 	sp = skb_sec_path(skb);
129 	x = sp->xvec[sp->len - 1];
130 	aead = x->data;
131 	esph = ip_esp_hdr(skb);
132 
133 	if (esph->spi != x->id.spi)
134 		return ERR_PTR(-EINVAL);
135 
136 	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
137 		return ERR_PTR(-EINVAL);
138 
139 	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
140 
141 	skb->encap_hdr_csum = 1;
142 
143 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev)
144 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
145 	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
146 		esp_features = features & ~NETIF_F_CSUM_MASK;
147 
148 	xo->flags |= XFRM_GSO_SEGMENT;
149 
150 	return x->outer_mode->gso_segment(x, skb, esp_features);
151 }
152 
153 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
154 {
155 	struct crypto_aead *aead = x->data;
156 	struct xfrm_offload *xo = xfrm_offload(skb);
157 
158 	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
159 		return -EINVAL;
160 
161 	if (!(xo->flags & CRYPTO_DONE))
162 		skb->ip_summed = CHECKSUM_NONE;
163 
164 	return esp_input_done2(skb, 0);
165 }
166 
167 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
168 {
169 	int err;
170 	int alen;
171 	int blksize;
172 	struct xfrm_offload *xo;
173 	struct ip_esp_hdr *esph;
174 	struct crypto_aead *aead;
175 	struct esp_info esp;
176 	bool hw_offload = true;
177 	__u32 seq;
178 
179 	esp.inplace = true;
180 
181 	xo = xfrm_offload(skb);
182 
183 	if (!xo)
184 		return -EINVAL;
185 
186 	if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev) {
187 		xo->flags |= CRYPTO_FALLBACK;
188 		hw_offload = false;
189 	}
190 
191 	esp.proto = xo->proto;
192 
193 	/* skb is pure payload to encrypt */
194 
195 	aead = x->data;
196 	alen = crypto_aead_authsize(aead);
197 
198 	esp.tfclen = 0;
199 	/* XXX: Add support for tfc padding here. */
200 
201 	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
202 	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
203 	esp.plen = esp.clen - skb->len - esp.tfclen;
204 	esp.tailen = esp.tfclen + esp.plen + alen;
205 
206 	esp.esph = ip_esp_hdr(skb);
207 
208 
209 	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
210 		esp.nfrags = esp_output_head(x, skb, &esp);
211 		if (esp.nfrags < 0)
212 			return esp.nfrags;
213 	}
214 
215 	seq = xo->seq.low;
216 
217 	esph = esp.esph;
218 	esph->spi = x->id.spi;
219 
220 	skb_push(skb, -skb_network_offset(skb));
221 
222 	if (xo->flags & XFRM_GSO_SEGMENT) {
223 		esph->seq_no = htonl(seq);
224 
225 		if (!skb_is_gso(skb))
226 			xo->seq.low++;
227 		else
228 			xo->seq.low += skb_shinfo(skb)->gso_segs;
229 	}
230 
231 	esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
232 
233 	ip_hdr(skb)->tot_len = htons(skb->len);
234 	ip_send_check(ip_hdr(skb));
235 
236 	if (hw_offload)
237 		return 0;
238 
239 	err = esp_output_tail(x, skb, &esp);
240 	if (err)
241 		return err;
242 
243 	secpath_reset(skb);
244 
245 	return 0;
246 }
247 
248 static const struct net_offload esp4_offload = {
249 	.callbacks = {
250 		.gro_receive = esp4_gro_receive,
251 		.gso_segment = esp4_gso_segment,
252 	},
253 };
254 
255 static const struct xfrm_type_offload esp_type_offload = {
256 	.description	= "ESP4 OFFLOAD",
257 	.owner		= THIS_MODULE,
258 	.proto	     	= IPPROTO_ESP,
259 	.input_tail	= esp_input_tail,
260 	.xmit		= esp_xmit,
261 	.encap		= esp4_gso_encap,
262 };
263 
264 static int __init esp4_offload_init(void)
265 {
266 	if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
267 		pr_info("%s: can't add xfrm type offload\n", __func__);
268 		return -EAGAIN;
269 	}
270 
271 	return inet_add_offload(&esp4_offload, IPPROTO_ESP);
272 }
273 
274 static void __exit esp4_offload_exit(void)
275 {
276 	if (xfrm_unregister_type_offload(&esp_type_offload, AF_INET) < 0)
277 		pr_info("%s: can't remove xfrm type offload\n", __func__);
278 
279 	inet_del_offload(&esp4_offload, IPPROTO_ESP);
280 }
281 
282 module_init(esp4_offload_init);
283 module_exit(esp4_offload_exit);
284 MODULE_LICENSE("GPL");
285 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
286 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);
287