net/ipv4/esp4_offload.c

   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
  31 static 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         skb_pull(skb, offset);
  42
  43         if ((err = 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                 err = secpath_set(skb);
  49                 if (err)
  50                         goto out;
  51
  52                 if (skb->sp->len == XFRM_MAX_DEPTH)
  53                         goto out;
  54
  55                 x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
  56                                       (xfrm_address_t *)&ip_hdr(skb)->daddr,
  57                                       spi, IPPROTO_ESP, AF_INET);
  58                 if (!x)
  59                         goto out;
  60
  61                 skb->sp->xvec[skb->sp->len++] = x;
  62                 skb->sp->olen++;
  63
  64                 xo = xfrm_offload(skb);
  65                 if (!xo) {
  66                         xfrm_state_put(x);
  67                         goto out;
  68                 }
  69         }
  70
  71         xo->flags |= XFRM_GRO;
  72
  73         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
  74         XFRM_SPI_SKB_CB(skb)->family = AF_INET;
  75         XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
  76         XFRM_SPI_SKB_CB(skb)->seq = seq;
  77
  78         /* We don't need to handle errors from xfrm_input, it does all
  79          * the error handling and frees the resources on error. */
  80         xfrm_input(skb, IPPROTO_ESP, spi, -2);
  81
  82         return ERR_PTR(-EINPROGRESS);
  83 out:
  84         skb_push(skb, offset);
  85         NAPI_GRO_CB(skb)->same_flow = 0;
  86         NAPI_GRO_CB(skb)->flush = 1;
  87
  88         return NULL;
  89 }
  90
  91 static void esp4_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
  92 {
  93         struct ip_esp_hdr *esph;
  94         struct iphdr *iph = ip_hdr(skb);
  95         struct xfrm_offload *xo = xfrm_offload(skb);
  96         int proto = iph->protocol;
  97
  98         skb_push(skb, -skb_network_offset(skb));
  99         esph = ip_esp_hdr(skb);
 100         *skb_mac_header(skb) = IPPROTO_ESP;
 101
 102         esph->spi = x->id.spi;
 103         esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
 104
 105         xo->proto = proto;
 106 }
 107
 108 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
 109                                         netdev_features_t features)
 110 {
 111         __u32 seq;
 112         int err = 0;
 113         struct sk_buff *skb2;
 114         struct xfrm_state *x;
 115         struct ip_esp_hdr *esph;
 116         struct crypto_aead *aead;
 117         struct sk_buff *segs = ERR_PTR(-EINVAL);
 118         netdev_features_t esp_features = features;
 119         struct xfrm_offload *xo = xfrm_offload(skb);
 120
 121         if (!xo)
 122                 goto out;
 123
 124         seq = xo->seq.low;
 125
 126         x = skb->sp->xvec[skb->sp->len - 1];
 127         aead = x->data;
 128         esph = ip_esp_hdr(skb);
 129
 130         if (esph->spi != x->id.spi)
 131                 goto out;
 132
 133         if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
 134                 goto out;
 135
 136         __skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
 137
 138         skb->encap_hdr_csum = 1;
 139
 140         if (!(features & NETIF_F_HW_ESP))
 141                 esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
 142
 143         segs = x->outer_mode->gso_segment(x, skb, esp_features);
 144         if (IS_ERR_OR_NULL(segs))
 145                 goto out;
 146
 147         __skb_pull(skb, skb->data - skb_mac_header(skb));
 148
 149         skb2 = segs;
 150         do {
 151                 struct sk_buff *nskb = skb2->next;
 152
 153                 xo = xfrm_offload(skb2);
 154                 xo->flags |= XFRM_GSO_SEGMENT;
 155                 xo->seq.low = seq;
 156                 xo->seq.hi = xfrm_replay_seqhi(x, seq);
 157
 158                 if(!(features & NETIF_F_HW_ESP))
 159                         xo->flags |= CRYPTO_FALLBACK;
 160
 161                 x->outer_mode->xmit(x, skb2);
 162
 163                 err = x->type_offload->xmit(x, skb2, esp_features);
 164                 if (err) {
 165                         kfree_skb_list(segs);
 166                         return ERR_PTR(err);
 167                 }
 168
 169                 if (!skb_is_gso(skb2))
 170                         seq++;
 171                 else
 172                         seq += skb_shinfo(skb2)->gso_segs;
 173
 174                 skb_push(skb2, skb2->mac_len);
 175                 skb2 = nskb;
 176         } while (skb2);
 177
 178 out:
 179         return segs;
 180 }
 181
 182 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
 183 {
 184         struct crypto_aead *aead = x->data;
 185
 186         if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
 187                 return -EINVAL;
 188
 189         skb->ip_summed = CHECKSUM_NONE;
 190
 191         return esp_input_done2(skb, 0);
 192 }
 193
 194 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
 195 {
 196         int err;
 197         int alen;
 198         int blksize;
 199         struct xfrm_offload *xo;
 200         struct ip_esp_hdr *esph;
 201         struct crypto_aead *aead;
 202         struct esp_info esp;
 203         bool hw_offload = true;
 204
 205         esp.inplace = true;
 206
 207         xo = xfrm_offload(skb);
 208
 209         if (!xo)
 210                 return -EINVAL;
 211
 212         if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
 213             (x->xso.dev != skb->dev)) {
 214                 xo->flags |= CRYPTO_FALLBACK;
 215                 hw_offload = false;
 216         }
 217
 218         esp.proto = xo->proto;
 219
 220         /* skb is pure payload to encrypt */
 221
 222         aead = x->data;
 223         alen = crypto_aead_authsize(aead);
 224
 225         esp.tfclen = 0;
 226         /* XXX: Add support for tfc padding here. */
 227
 228         blksize = ALIGN(crypto_aead_blocksize(aead), 4);
 229         esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
 230         esp.plen = esp.clen - skb->len - esp.tfclen;
 231         esp.tailen = esp.tfclen + esp.plen + alen;
 232
 233         esp.esph = ip_esp_hdr(skb);
 234
 235
 236         if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
 237                 esp.nfrags = esp_output_head(x, skb, &esp);
 238                 if (esp.nfrags < 0)
 239                         return esp.nfrags;
 240         }
 241
 242         esph = esp.esph;
 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(xo->seq.low);
 249         } else {
 250                 ip_hdr(skb)->tot_len = htons(skb->len);
 251                 ip_send_check(ip_hdr(skb));
 252         }
 253
 254         if (hw_offload)
 255                 return 0;
 256
 257         esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
 258
 259         err = esp_output_tail(x, skb, &esp);
 260         if (err < 0)
 261                 return err;
 262
 263         secpath_reset(skb);
 264
 265         return 0;
 266 }
 267
 268 static const struct net_offload esp4_offload = {
 269         .callbacks = {
 270                 .gro_receive = esp4_gro_receive,
 271                 .gso_segment = esp4_gso_segment,
 272         },
 273 };
 274
 275 static const struct xfrm_type_offload esp_type_offload = {
 276         .description    = "ESP4 OFFLOAD",
 277         .owner          = THIS_MODULE,
 278         .proto          = IPPROTO_ESP,
 279         .input_tail     = esp_input_tail,
 280         .xmit           = esp_xmit,
 281         .encap          = esp4_gso_encap,
 282 };
 283
 284 static int __init esp4_offload_init(void)
 285 {
 286         if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
 287                 pr_info("%s: can't add xfrm type offload\n", __func__);
 288                 return -EAGAIN;
 289         }
 290
 291         return inet_add_offload(&esp4_offload, IPPROTO_ESP);
 292 }
 293
 294 static void __exit esp4_offload_exit(void)
 295 {
 296         if (xfrm_unregister_type_offload(&esp_type_offload, AF_INET) < 0)
 297                 pr_info("%s: can't remove xfrm type offload\n", __func__);
 298
 299         inet_del_offload(&esp4_offload, IPPROTO_ESP);
 300 }
 301
 302 module_init(esp4_offload_init);
 303 module_exit(esp4_offload_exit);
 304 MODULE_LICENSE("GPL");
 305 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");