esp4_offload.c

  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
 30static 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);
 94out_reset:
 95	secpath_reset(skb);
 96out:
 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
104static 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
121static struct sk_buff *xfrm4_tunnel_gso_segment(struct xfrm_state *x,
122						struct sk_buff *skb,
123						netdev_features_t features)
124{
125	struct xfrm_offload *xo = xfrm_offload(skb);
126	const struct xfrm_mode *inner_mode = xfrm_ip2inner_mode(x, xo->proto);
127	__be16 type = inner_mode->family == AF_INET6 ? htons(ETH_P_IPV6)
128						     : htons(ETH_P_IP);
129
130	return skb_eth_gso_segment(skb, features, type);
131}
132
133static struct sk_buff *xfrm4_transport_gso_segment(struct xfrm_state *x,
134						   struct sk_buff *skb,
135						   netdev_features_t features)
136{
137	const struct net_offload *ops;
138	struct sk_buff *segs = ERR_PTR(-EINVAL);
139	struct xfrm_offload *xo = xfrm_offload(skb);
140
141	skb->transport_header += x->props.header_len;
142	ops = rcu_dereference(inet_offloads[xo->proto]);
143	if (likely(ops && ops->callbacks.gso_segment))
144		segs = ops->callbacks.gso_segment(skb, features);
145
146	return segs;
147}
148
149static struct sk_buff *xfrm4_beet_gso_segment(struct xfrm_state *x,
150					      struct sk_buff *skb,
151					      netdev_features_t features)
152{
153	struct xfrm_offload *xo = xfrm_offload(skb);
154	struct sk_buff *segs = ERR_PTR(-EINVAL);
155	const struct net_offload *ops;
156	u8 proto = xo->proto;
157
158	skb->transport_header += x->props.header_len;
159
160	if (x->sel.family != AF_INET6) {
161		if (proto == IPPROTO_BEETPH) {
162			struct ip_beet_phdr *ph =
163				(struct ip_beet_phdr *)skb->data;
164
165			skb->transport_header += ph->hdrlen * 8;
166			proto = ph->nexthdr;
167		} else {
168			skb->transport_header -= IPV4_BEET_PHMAXLEN;
169		}
170	} else {
171		__be16 frag;
172
173		skb->transport_header +=
174			ipv6_skip_exthdr(skb, 0, &proto, &frag);
175		if (proto == IPPROTO_TCP)
176			skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
177	}
178
179	if (proto == IPPROTO_IPV6)
180		skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP4;
181
182	__skb_pull(skb, skb_transport_offset(skb));
183	ops = rcu_dereference(inet_offloads[proto]);
184	if (likely(ops && ops->callbacks.gso_segment))
185		segs = ops->callbacks.gso_segment(skb, features);
186
187	return segs;
188}
189
190static struct sk_buff *xfrm4_outer_mode_gso_segment(struct xfrm_state *x,
191						    struct sk_buff *skb,
192						    netdev_features_t features)
193{
194	switch (x->outer_mode.encap) {
195	case XFRM_MODE_TUNNEL:
196		return xfrm4_tunnel_gso_segment(x, skb, features);
197	case XFRM_MODE_TRANSPORT:
198		return xfrm4_transport_gso_segment(x, skb, features);
199	case XFRM_MODE_BEET:
200		return xfrm4_beet_gso_segment(x, skb, features);
201	}
202
203	return ERR_PTR(-EOPNOTSUPP);
204}
205
206static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
207				        netdev_features_t features)
208{
209	struct xfrm_state *x;
210	struct ip_esp_hdr *esph;
211	struct crypto_aead *aead;
212	netdev_features_t esp_features = features;
213	struct xfrm_offload *xo = xfrm_offload(skb);
214	struct sec_path *sp;
215
216	if (!xo)
217		return ERR_PTR(-EINVAL);
218
219	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
220		return ERR_PTR(-EINVAL);
221
222	sp = skb_sec_path(skb);
223	x = sp->xvec[sp->len - 1];
224	aead = x->data;
225	esph = ip_esp_hdr(skb);
226
227	if (esph->spi != x->id.spi)
228		return ERR_PTR(-EINVAL);
229
230	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
231		return ERR_PTR(-EINVAL);
232
233	__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
234
235	skb->encap_hdr_csum = 1;
236
237	if ((!(skb->dev->gso_partial_features & NETIF_F_HW_ESP) &&
238	     !(features & NETIF_F_HW_ESP)) || x->xso.dev != skb->dev)
239		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK |
240					    NETIF_F_SCTP_CRC);
241	else if (!(features & NETIF_F_HW_ESP_TX_CSUM) &&
242		 !(skb->dev->gso_partial_features & NETIF_F_HW_ESP_TX_CSUM))
243		esp_features = features & ~(NETIF_F_CSUM_MASK |
244					    NETIF_F_SCTP_CRC);
245
246	xo->flags |= XFRM_GSO_SEGMENT;
247
248	return xfrm4_outer_mode_gso_segment(x, skb, esp_features);
249}
250
251static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
252{
253	struct crypto_aead *aead = x->data;
254	struct xfrm_offload *xo = xfrm_offload(skb);
255
256	if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
257		return -EINVAL;
258
259	if (!(xo->flags & CRYPTO_DONE))
260		skb->ip_summed = CHECKSUM_NONE;
261
262	return esp_input_done2(skb, 0);
263}
264
265static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
266{
267	int err;
268	int alen;
269	int blksize;
270	struct xfrm_offload *xo;
271	struct ip_esp_hdr *esph;
272	struct crypto_aead *aead;
273	struct esp_info esp;
274	bool hw_offload = true;
275	__u32 seq;
276	int encap_type = 0;
277
278	esp.inplace = true;
279
280	xo = xfrm_offload(skb);
281
282	if (!xo)
283		return -EINVAL;
284
285	if ((!(features & NETIF_F_HW_ESP) &&
286	     !(skb->dev->gso_partial_features & NETIF_F_HW_ESP)) ||
287	    x->xso.dev != skb->dev) {
288		xo->flags |= CRYPTO_FALLBACK;
289		hw_offload = false;
290	}
291
292	esp.proto = xo->proto;
293
294	/* skb is pure payload to encrypt */
295
296	aead = x->data;
297	alen = crypto_aead_authsize(aead);
298
299	esp.tfclen = 0;
300	/* XXX: Add support for tfc padding here. */
301
302	blksize = ALIGN(crypto_aead_blocksize(aead), 4);
303	esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
304	esp.plen = esp.clen - skb->len - esp.tfclen;
305	esp.tailen = esp.tfclen + esp.plen + alen;
306
307	esp.esph = ip_esp_hdr(skb);
308
309	if (x->encap)
310		encap_type = x->encap->encap_type;
311
312	if (!hw_offload || !skb_is_gso(skb) || (hw_offload && encap_type == UDP_ENCAP_ESPINUDP)) {
313		esp.nfrags = esp_output_head(x, skb, &esp);
314		if (esp.nfrags < 0)
315			return esp.nfrags;
316	}
317
318	seq = xo->seq.low;
319
320	esph = esp.esph;
321	esph->spi = x->id.spi;
322
323	skb_push(skb, -skb_network_offset(skb));
324
325	if (xo->flags & XFRM_GSO_SEGMENT) {
326		esph->seq_no = htonl(seq);
327
328		if (!skb_is_gso(skb))
329			xo->seq.low++;
330		else
331			xo->seq.low += skb_shinfo(skb)->gso_segs;
332	}
333
334	if (xo->seq.low < seq)
335		xo->seq.hi++;
336
337	esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
338
339	if (hw_offload && encap_type == UDP_ENCAP_ESPINUDP) {
340		/* In the XFRM stack, the encapsulation protocol is set to iphdr->protocol by
341		 * setting *skb_mac_header(skb) (see esp_output_udp_encap()) where skb->mac_header
342		 * points to iphdr->protocol (see xfrm4_tunnel_encap_add()).
343		 * However, in esp_xmit(), skb->mac_header doesn't point to iphdr->protocol.
344		 * Therefore, the protocol field needs to be corrected.
345		 */
346		ip_hdr(skb)->protocol = IPPROTO_UDP;
347
348		esph->seq_no = htonl(seq);
349	}
350
351	ip_hdr(skb)->tot_len = htons(skb->len);
352	ip_send_check(ip_hdr(skb));
353
354	if (hw_offload) {
355		if (!skb_ext_add(skb, SKB_EXT_SEC_PATH))
356			return -ENOMEM;
357
358		xo = xfrm_offload(skb);
359		if (!xo)
360			return -EINVAL;
361
362		xo->flags |= XFRM_XMIT;
363		return 0;
364	}
365
366	err = esp_output_tail(x, skb, &esp);
367	if (err)
368		return err;
369
370	secpath_reset(skb);
371
372	if (skb_needs_linearize(skb, skb->dev->features) &&
373	    __skb_linearize(skb))
374		return -ENOMEM;
375	return 0;
376}
377
378static const struct net_offload esp4_offload = {
379	.callbacks = {
380		.gro_receive = esp4_gro_receive,
381		.gso_segment = esp4_gso_segment,
382	},
383};
384
385static const struct xfrm_type_offload esp_type_offload = {
386	.owner		= THIS_MODULE,
387	.proto	     	= IPPROTO_ESP,
388	.input_tail	= esp_input_tail,
389	.xmit		= esp_xmit,
390	.encap		= esp4_gso_encap,
391};
392
393static int __init esp4_offload_init(void)
394{
395	if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
396		pr_info("%s: can't add xfrm type offload\n", __func__);
397		return -EAGAIN;
398	}
399
400	return inet_add_offload(&esp4_offload, IPPROTO_ESP);
401}
402
403static void __exit esp4_offload_exit(void)
404{
405	xfrm_unregister_type_offload(&esp_type_offload, AF_INET);
406	inet_del_offload(&esp4_offload, IPPROTO_ESP);
407}
408
409module_init(esp4_offload_init);
410module_exit(esp4_offload_exit);
411MODULE_LICENSE("GPL");
412MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
413MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);
414MODULE_DESCRIPTION("IPV4 GSO/GRO offload support");