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
 31static struct sk_buff **esp4_gro_receive(struct sk_buff **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		err = secpath_set(skb);
 50		if (err)
 51			goto out;
 52
 53		if (skb->sp->len == XFRM_MAX_DEPTH)
 54			goto out;
 55
 56		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
 57				      (xfrm_address_t *)&ip_hdr(skb)->daddr,
 58				      spi, IPPROTO_ESP, AF_INET);
 59		if (!x)
 60			goto out;
 61
 62		skb->sp->xvec[skb->sp->len++] = x;
 63		skb->sp->olen++;
 64
 65		xo = xfrm_offload(skb);
 66		if (!xo) {
 67			xfrm_state_put(x);
 68			goto out;
 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);
 84out:
 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
 92static 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
109static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
110				        netdev_features_t features)
111{
112	struct xfrm_state *x;
113	struct ip_esp_hdr *esph;
114	struct crypto_aead *aead;
115	netdev_features_t esp_features = features;
116	struct xfrm_offload *xo = xfrm_offload(skb);
117
118	if (!xo)
119		return ERR_PTR(-EINVAL);
120
121	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
122		return ERR_PTR(-EINVAL);
123
124	x = skb->sp->xvec[skb->sp->len - 1];
125	aead = x->data;
126	esph = ip_esp_hdr(skb);
127
128	if (esph->spi != x->id.spi)
129		return ERR_PTR(-EINVAL);
130
131	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
132		return ERR_PTR(-EINVAL);
133
134	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
135
136	skb->encap_hdr_csum = 1;
137
138	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
139	    (x->xso.dev != skb->dev))
140		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
141	else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
142		esp_features = features & ~NETIF_F_CSUM_MASK;
143
144	xo->flags |= XFRM_GSO_SEGMENT;
145
146	return x->outer_mode->gso_segment(x, skb, esp_features);
147}
148
149static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
150{
151	struct crypto_aead *aead = x->data;
152	struct xfrm_offload *xo = xfrm_offload(skb);
153
154	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
155		return -EINVAL;
156
157	if (!(xo->flags & CRYPTO_DONE))
158		skb->ip_summed = CHECKSUM_NONE;
159
160	return esp_input_done2(skb, 0);
161}
162
163static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
164{
165	int err;
166	int alen;
167	int blksize;
168	struct xfrm_offload *xo;
169	struct ip_esp_hdr *esph;
170	struct crypto_aead *aead;
171	struct esp_info esp;
172	bool hw_offload = true;
173	__u32 seq;
174
175	esp.inplace = true;
176
177	xo = xfrm_offload(skb);
178
179	if (!xo)
180		return -EINVAL;
181
182	if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
183	    (x->xso.dev != skb->dev)) {
184		xo->flags |= CRYPTO_FALLBACK;
185		hw_offload = false;
186	}
187
188	esp.proto = xo->proto;
189
190	/* skb is pure payload to encrypt */
191
192	aead = x->data;
193	alen = crypto_aead_authsize(aead);
194
195	esp.tfclen = 0;
196	/* XXX: Add support for tfc padding here. */
197
198	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
199	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
200	esp.plen = esp.clen - skb->len - esp.tfclen;
201	esp.tailen = esp.tfclen + esp.plen + alen;
202
203	esp.esph = ip_esp_hdr(skb);
204
205
206	if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
207		esp.nfrags = esp_output_head(x, skb, &esp);
208		if (esp.nfrags < 0)
209			return esp.nfrags;
210	}
211
212	seq = xo->seq.low;
213
214	esph = esp.esph;
215	esph->spi = x->id.spi;
216
217	skb_push(skb, -skb_network_offset(skb));
218
219	if (xo->flags & XFRM_GSO_SEGMENT) {
220		esph->seq_no = htonl(seq);
221
222		if (!skb_is_gso(skb))
223			xo->seq.low++;
224		else
225			xo->seq.low += skb_shinfo(skb)->gso_segs;
226	}
227
228	esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
229
230	ip_hdr(skb)->tot_len = htons(skb->len);
231	ip_send_check(ip_hdr(skb));
232
233	if (hw_offload)
234		return 0;
235
236	err = esp_output_tail(x, skb, &esp);
237	if (err)
238		return err;
239
240	secpath_reset(skb);
241
242	return 0;
243}
244
245static const struct net_offload esp4_offload = {
246	.callbacks = {
247		.gro_receive = esp4_gro_receive,
248		.gso_segment = esp4_gso_segment,
249	},
250};
251
252static const struct xfrm_type_offload esp_type_offload = {
253	.description	= "ESP4 OFFLOAD",
254	.owner		= THIS_MODULE,
255	.proto	     	= IPPROTO_ESP,
256	.input_tail	= esp_input_tail,
257	.xmit		= esp_xmit,
258	.encap		= esp4_gso_encap,
259};
260
261static int __init esp4_offload_init(void)
262{
263	if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
264		pr_info("%s: can't add xfrm type offload\n", __func__);
265		return -EAGAIN;
266	}
267
268	return inet_add_offload(&esp4_offload, IPPROTO_ESP);
269}
270
271static void __exit esp4_offload_exit(void)
272{
273	if (xfrm_unregister_type_offload(&esp_type_offload, AF_INET) < 0)
274		pr_info("%s: can't remove xfrm type offload\n", __func__);
275
276	inet_del_offload(&esp4_offload, IPPROTO_ESP);
277}
278
279module_init(esp4_offload_init);
280module_exit(esp4_offload_exit);
281MODULE_LICENSE("GPL");
282MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
283MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);