net/ipv6/esp6_offload.c

   1 /*
   2  * IPV6 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/ip6_route.h>
  30 #include <net/ipv6.h>
  31 #include <linux/icmpv6.h>
  32
  33 static __u16 esp6_nexthdr_esp_offset(struct ipv6hdr *ipv6_hdr, int nhlen)
  34 {
  35         int off = sizeof(struct ipv6hdr);
  36         struct ipv6_opt_hdr *exthdr;
  37
  38         if (likely(ipv6_hdr->nexthdr == NEXTHDR_ESP))
  39                 return offsetof(struct ipv6hdr, nexthdr);
  40
  41         while (off < nhlen) {
  42                 exthdr = (void *)ipv6_hdr + off;
  43                 if (exthdr->nexthdr == NEXTHDR_ESP)
  44                         return off;
  45
  46                 off += ipv6_optlen(exthdr);
  47         }
  48
  49         return 0;
  50 }
  51
  52 static struct sk_buff **esp6_gro_receive(struct sk_buff **head,
  53                                          struct sk_buff *skb)
  54 {
  55         int offset = skb_gro_offset(skb);
  56         struct xfrm_offload *xo;
  57         struct xfrm_state *x;
  58         __be32 seq;
  59         __be32 spi;
  60         int nhoff;
  61         int err;
  62
  63         if (!pskb_pull(skb, offset))
  64                 return NULL;
  65
  66         if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
  67                 goto out;
  68
  69         xo = xfrm_offload(skb);
  70         if (!xo || !(xo->flags & CRYPTO_DONE)) {
  71                 err = secpath_set(skb);
  72                 if (err)
  73                         goto out;
  74
  75                 if (skb->sp->len == XFRM_MAX_DEPTH)
  76                         goto out;
  77
  78                 x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
  79                                       (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
  80                                       spi, IPPROTO_ESP, AF_INET6);
  81                 if (!x)
  82                         goto out;
  83
  84                 skb->sp->xvec[skb->sp->len++] = x;
  85                 skb->sp->olen++;
  86
  87                 xo = xfrm_offload(skb);
  88                 if (!xo) {
  89                         xfrm_state_put(x);
  90                         goto out;
  91                 }
  92         }
  93
  94         xo->flags |= XFRM_GRO;
  95
  96         nhoff = esp6_nexthdr_esp_offset(ipv6_hdr(skb), offset);
  97         if (!nhoff)
  98                 goto out;
  99
 100         IP6CB(skb)->nhoff = nhoff;
 101         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
 102         XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
 103         XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
 104         XFRM_SPI_SKB_CB(skb)->seq = seq;
 105
 106         /* We don't need to handle errors from xfrm_input, it does all
 107          * the error handling and frees the resources on error. */
 108         xfrm_input(skb, IPPROTO_ESP, spi, -2);
 109
 110         return ERR_PTR(-EINPROGRESS);
 111 out:
 112         skb_push(skb, offset);
 113         NAPI_GRO_CB(skb)->same_flow = 0;
 114         NAPI_GRO_CB(skb)->flush = 1;
 115
 116         return NULL;
 117 }
 118
 119 static void esp6_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
 120 {
 121         struct ip_esp_hdr *esph;
 122         struct ipv6hdr *iph = ipv6_hdr(skb);
 123         struct xfrm_offload *xo = xfrm_offload(skb);
 124         int proto = iph->nexthdr;
 125
 126         skb_push(skb, -skb_network_offset(skb));
 127         esph = ip_esp_hdr(skb);
 128         *skb_mac_header(skb) = IPPROTO_ESP;
 129
 130         esph->spi = x->id.spi;
 131         esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
 132
 133         xo->proto = proto;
 134 }
 135
 136 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
 137                                         netdev_features_t features)
 138 {
 139         __u32 seq;
 140         int err = 0;
 141         struct sk_buff *skb2;
 142         struct xfrm_state *x;
 143         struct ip_esp_hdr *esph;
 144         struct crypto_aead *aead;
 145         struct sk_buff *segs = ERR_PTR(-EINVAL);
 146         netdev_features_t esp_features = features;
 147         struct xfrm_offload *xo = xfrm_offload(skb);
 148
 149         if (!xo)
 150                 goto out;
 151
 152         if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
 153                 goto out;
 154
 155         seq = xo->seq.low;
 156
 157         x = skb->sp->xvec[skb->sp->len - 1];
 158         aead = x->data;
 159         esph = ip_esp_hdr(skb);
 160
 161         if (esph->spi != x->id.spi)
 162                 goto out;
 163
 164         if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
 165                 goto out;
 166
 167         __skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
 168
 169         skb->encap_hdr_csum = 1;
 170
 171         if (!(features & NETIF_F_HW_ESP))
 172                 esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
 173
 174         segs = x->outer_mode->gso_segment(x, skb, esp_features);
 175         if (IS_ERR_OR_NULL(segs))
 176                 goto out;
 177
 178         __skb_pull(skb, skb->data - skb_mac_header(skb));
 179
 180         skb2 = segs;
 181         do {
 182                 struct sk_buff *nskb = skb2->next;
 183
 184                 xo = xfrm_offload(skb2);
 185                 xo->flags |= XFRM_GSO_SEGMENT;
 186                 xo->seq.low = seq;
 187                 xo->seq.hi = xfrm_replay_seqhi(x, seq);
 188
 189                 if(!(features & NETIF_F_HW_ESP))
 190                         xo->flags |= CRYPTO_FALLBACK;
 191
 192                 x->outer_mode->xmit(x, skb2);
 193
 194                 err = x->type_offload->xmit(x, skb2, esp_features);
 195                 if (err) {
 196                         kfree_skb_list(segs);
 197                         return ERR_PTR(err);
 198                 }
 199
 200                 if (!skb_is_gso(skb2))
 201                         seq++;
 202                 else
 203                         seq += skb_shinfo(skb2)->gso_segs;
 204
 205                 skb_push(skb2, skb2->mac_len);
 206                 skb2 = nskb;
 207         } while (skb2);
 208
 209 out:
 210         return segs;
 211 }
 212
 213 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
 214 {
 215         struct crypto_aead *aead = x->data;
 216         struct xfrm_offload *xo = xfrm_offload(skb);
 217
 218         if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
 219                 return -EINVAL;
 220
 221         if (!(xo->flags & CRYPTO_DONE))
 222                 skb->ip_summed = CHECKSUM_NONE;
 223
 224         return esp6_input_done2(skb, 0);
 225 }
 226
 227 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
 228 {
 229         int err;
 230         int alen;
 231         int blksize;
 232         struct xfrm_offload *xo;
 233         struct ip_esp_hdr *esph;
 234         struct crypto_aead *aead;
 235         struct esp_info esp;
 236         bool hw_offload = true;
 237
 238         esp.inplace = true;
 239
 240         xo = xfrm_offload(skb);
 241
 242         if (!xo)
 243                 return -EINVAL;
 244
 245         if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
 246             (x->xso.dev != skb->dev)) {
 247                 xo->flags |= CRYPTO_FALLBACK;
 248                 hw_offload = false;
 249         }
 250
 251         esp.proto = xo->proto;
 252
 253         /* skb is pure payload to encrypt */
 254
 255         aead = x->data;
 256         alen = crypto_aead_authsize(aead);
 257
 258         esp.tfclen = 0;
 259         /* XXX: Add support for tfc padding here. */
 260
 261         blksize = ALIGN(crypto_aead_blocksize(aead), 4);
 262         esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
 263         esp.plen = esp.clen - skb->len - esp.tfclen;
 264         esp.tailen = esp.tfclen + esp.plen + alen;
 265
 266         if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
 267                 esp.nfrags = esp6_output_head(x, skb, &esp);
 268                 if (esp.nfrags < 0)
 269                         return esp.nfrags;
 270         }
 271
 272         esph = ip_esp_hdr(skb);
 273         esph->spi = x->id.spi;
 274
 275         skb_push(skb, -skb_network_offset(skb));
 276
 277         if (xo->flags & XFRM_GSO_SEGMENT) {
 278                 esph->seq_no = htonl(xo->seq.low);
 279         } else {
 280                 int len;
 281
 282                 len = skb->len - sizeof(struct ipv6hdr);
 283                 if (len > IPV6_MAXPLEN)
 284                         len = 0;
 285
 286                 ipv6_hdr(skb)->payload_len = htons(len);
 287         }
 288
 289         if (hw_offload)
 290                 return 0;
 291
 292         esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
 293
 294         err = esp6_output_tail(x, skb, &esp);
 295         if (err)
 296                 return err;
 297
 298         secpath_reset(skb);
 299
 300         return 0;
 301 }
 302
 303 static const struct net_offload esp6_offload = {
 304         .callbacks = {
 305                 .gro_receive = esp6_gro_receive,
 306                 .gso_segment = esp6_gso_segment,
 307         },
 308 };
 309
 310 static const struct xfrm_type_offload esp6_type_offload = {
 311         .description    = "ESP6 OFFLOAD",
 312         .owner          = THIS_MODULE,
 313         .proto          = IPPROTO_ESP,
 314         .input_tail     = esp6_input_tail,
 315         .xmit           = esp6_xmit,
 316         .encap          = esp6_gso_encap,
 317 };
 318
 319 static int __init esp6_offload_init(void)
 320 {
 321         if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
 322                 pr_info("%s: can't add xfrm type offload\n", __func__);
 323                 return -EAGAIN;
 324         }
 325
 326         return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
 327 }
 328
 329 static void __exit esp6_offload_exit(void)
 330 {
 331         if (xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6) < 0)
 332                 pr_info("%s: can't remove xfrm type offload\n", __func__);
 333
 334         inet6_del_offload(&esp6_offload, IPPROTO_ESP);
 335 }
 336
 337 module_init(esp6_offload_init);
 338 module_exit(esp6_offload_exit);
 339 MODULE_LICENSE("GPL");
 340 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 341 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET6, XFRM_PROTO_ESP);