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 list_head *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         u8 proto = iph->nexthdr;
 125
 126         skb_push(skb, -skb_network_offset(skb));
 127
 128         if (x->outer_mode->encap == XFRM_MODE_TRANSPORT) {
 129                 __be16 frag;
 130
 131                 ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &proto, &frag);
 132         }
 133
 134         esph = ip_esp_hdr(skb);
 135         *skb_mac_header(skb) = IPPROTO_ESP;
 136
 137         esph->spi = x->id.spi;
 138         esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
 139
 140         xo->proto = proto;
 141 }
 142
 143 static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
 144                                         netdev_features_t features)
 145 {
 146         struct xfrm_state *x;
 147         struct ip_esp_hdr *esph;
 148         struct crypto_aead *aead;
 149         netdev_features_t esp_features = features;
 150         struct xfrm_offload *xo = xfrm_offload(skb);
 151
 152         if (!xo)
 153                 return ERR_PTR(-EINVAL);
 154
 155         if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
 156                 return ERR_PTR(-EINVAL);
 157
 158         x = skb->sp->xvec[skb->sp->len - 1];
 159         aead = x->data;
 160         esph = ip_esp_hdr(skb);
 161
 162         if (esph->spi != x->id.spi)
 163                 return ERR_PTR(-EINVAL);
 164
 165         if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
 166                 return ERR_PTR(-EINVAL);
 167
 168         __skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
 169
 170         skb->encap_hdr_csum = 1;
 171
 172         if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev)
 173                 esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
 174         else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
 175                 esp_features = features & ~NETIF_F_CSUM_MASK;
 176
 177         xo->flags |= XFRM_GSO_SEGMENT;
 178
 179         return x->outer_mode->gso_segment(x, skb, esp_features);
 180 }
 181
 182 static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
 183 {
 184         struct crypto_aead *aead = x->data;
 185         struct xfrm_offload *xo = xfrm_offload(skb);
 186
 187         if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
 188                 return -EINVAL;
 189
 190         if (!(xo->flags & CRYPTO_DONE))
 191                 skb->ip_summed = CHECKSUM_NONE;
 192
 193         return esp6_input_done2(skb, 0);
 194 }
 195
 196 static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
 197 {
 198         int len;
 199         int err;
 200         int alen;
 201         int blksize;
 202         struct xfrm_offload *xo;
 203         struct ip_esp_hdr *esph;
 204         struct crypto_aead *aead;
 205         struct esp_info esp;
 206         bool hw_offload = true;
 207         __u32 seq;
 208
 209         esp.inplace = true;
 210
 211         xo = xfrm_offload(skb);
 212
 213         if (!xo)
 214                 return -EINVAL;
 215
 216         if (!(features & NETIF_F_HW_ESP) || x->xso.dev != skb->dev) {
 217                 xo->flags |= CRYPTO_FALLBACK;
 218                 hw_offload = false;
 219         }
 220
 221         esp.proto = xo->proto;
 222
 223         /* skb is pure payload to encrypt */
 224
 225         aead = x->data;
 226         alen = crypto_aead_authsize(aead);
 227
 228         esp.tfclen = 0;
 229         /* XXX: Add support for tfc padding here. */
 230
 231         blksize = ALIGN(crypto_aead_blocksize(aead), 4);
 232         esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
 233         esp.plen = esp.clen - skb->len - esp.tfclen;
 234         esp.tailen = esp.tfclen + esp.plen + alen;
 235
 236         if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
 237                 esp.nfrags = esp6_output_head(x, skb, &esp);
 238                 if (esp.nfrags < 0)
 239                         return esp.nfrags;
 240         }
 241
 242         seq = xo->seq.low;
 243
 244         esph = ip_esp_hdr(skb);
 245         esph->spi = x->id.spi;
 246
 247         skb_push(skb, -skb_network_offset(skb));
 248
 249         if (xo->flags & XFRM_GSO_SEGMENT) {
 250                 esph->seq_no = htonl(seq);
 251
 252                 if (!skb_is_gso(skb))
 253                         xo->seq.low++;
 254                 else
 255                         xo->seq.low += skb_shinfo(skb)->gso_segs;
 256         }
 257
 258         esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
 259
 260         len = skb->len - sizeof(struct ipv6hdr);
 261         if (len > IPV6_MAXPLEN)
 262                 len = 0;
 263
 264         ipv6_hdr(skb)->payload_len = htons(len);
 265
 266         if (hw_offload)
 267                 return 0;
 268
 269         err = esp6_output_tail(x, skb, &esp);
 270         if (err)
 271                 return err;
 272
 273         secpath_reset(skb);
 274
 275         return 0;
 276 }
 277
 278 static const struct net_offload esp6_offload = {
 279         .callbacks = {
 280                 .gro_receive = esp6_gro_receive,
 281                 .gso_segment = esp6_gso_segment,
 282         },
 283 };
 284
 285 static const struct xfrm_type_offload esp6_type_offload = {
 286         .description    = "ESP6 OFFLOAD",
 287         .owner          = THIS_MODULE,
 288         .proto          = IPPROTO_ESP,
 289         .input_tail     = esp6_input_tail,
 290         .xmit           = esp6_xmit,
 291         .encap          = esp6_gso_encap,
 292 };
 293
 294 static int __init esp6_offload_init(void)
 295 {
 296         if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
 297                 pr_info("%s: can't add xfrm type offload\n", __func__);
 298                 return -EAGAIN;
 299         }
 300
 301         return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
 302 }
 303
 304 static void __exit esp6_offload_exit(void)
 305 {
 306         if (xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6) < 0)
 307                 pr_info("%s: can't remove xfrm type offload\n", __func__);
 308
 309         inet6_del_offload(&esp6_offload, IPPROTO_ESP);
 310 }
 311
 312 module_init(esp6_offload_init);
 313 module_exit(esp6_offload_exit);
 314 MODULE_LICENSE("GPL");
 315 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 316 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET6, XFRM_PROTO_ESP);