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