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         if (!pskb_pull(skb, offset))
  42                 return NULL;
  43
  44         if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
  45                 goto out;
  46
  47         xo = xfrm_offload(skb);
  48         if (!xo || !(xo->flags & CRYPTO_DONE)) {
  49                 err = secpath_set(skb);
  50                 if (err)
  51                         goto out;
  52
  53                 if (skb->sp->len == XFRM_MAX_DEPTH)
  54                         goto out;
  55
  56                 x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
  57                                       (xfrm_address_t *)&ip_hdr(skb)->daddr,
  58                                       spi, IPPROTO_ESP, AF_INET);
  59                 if (!x)
  60                         goto out;
  61
  62                 skb->sp->xvec[skb->sp->len++] = x;
  63                 skb->sp->olen++;
  64
  65                 xo = xfrm_offload(skb);
  66                 if (!xo) {
  67                         xfrm_state_put(x);
  68                         goto out;
  69                 }
  70         }
  71
  72         xo->flags |= XFRM_GRO;
  73
  74         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
  75         XFRM_SPI_SKB_CB(skb)->family = AF_INET;
  76         XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
  77         XFRM_SPI_SKB_CB(skb)->seq = seq;
  78
  79         /* We don't need to handle errors from xfrm_input, it does all
  80          * the error handling and frees the resources on error. */
  81         xfrm_input(skb, IPPROTO_ESP, spi, -2);
  82
  83         return ERR_PTR(-EINPROGRESS);
  84 out:
  85         skb_push(skb, offset);
  86         NAPI_GRO_CB(skb)->same_flow = 0;
  87         NAPI_GRO_CB(skb)->flush = 1;
  88
  89         return NULL;
  90 }
  91
  92 static void esp4_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
  93 {
  94         struct ip_esp_hdr *esph;
  95         struct iphdr *iph = ip_hdr(skb);
  96         struct xfrm_offload *xo = xfrm_offload(skb);
  97         int proto = iph->protocol;
  98
  99         skb_push(skb, -skb_network_offset(skb));
 100         esph = ip_esp_hdr(skb);
 101         *skb_mac_header(skb) = IPPROTO_ESP;
 102
 103         esph->spi = x->id.spi;
 104         esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
 105
 106         xo->proto = proto;
 107 }
 108
 109 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
 110                                         netdev_features_t features)
 111 {
 112         __u32 seq;
 113         int err = 0;
 114         struct sk_buff *skb2;
 115         struct xfrm_state *x;
 116         struct ip_esp_hdr *esph;
 117         struct crypto_aead *aead;
 118         struct sk_buff *segs = ERR_PTR(-EINVAL);
 119         netdev_features_t esp_features = features;
 120         struct xfrm_offload *xo = xfrm_offload(skb);
 121
 122         if (!xo)
 123                 goto out;
 124
 125         seq = xo->seq.low;
 126
 127         x = skb->sp->xvec[skb->sp->len - 1];
 128         aead = x->data;
 129         esph = ip_esp_hdr(skb);
 130
 131         if (esph->spi != x->id.spi)
 132                 goto out;
 133
 134         if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
 135                 goto out;
 136
 137         __skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
 138
 139         skb->encap_hdr_csum = 1;
 140
 141         if (!(features & NETIF_F_HW_ESP))
 142                 esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
 143
 144         segs = x->outer_mode->gso_segment(x, skb, esp_features);
 145         if (IS_ERR_OR_NULL(segs))
 146                 goto out;
 147
 148         __skb_pull(skb, skb->data - skb_mac_header(skb));
 149
 150         skb2 = segs;
 151         do {
 152                 struct sk_buff *nskb = skb2->next;
 153
 154                 xo = xfrm_offload(skb2);
 155                 xo->flags |= XFRM_GSO_SEGMENT;
 156                 xo->seq.low = seq;
 157                 xo->seq.hi = xfrm_replay_seqhi(x, seq);
 158
 159                 if(!(features & NETIF_F_HW_ESP))
 160                         xo->flags |= CRYPTO_FALLBACK;
 161
 162                 x->outer_mode->xmit(x, skb2);
 163
 164                 err = x->type_offload->xmit(x, skb2, esp_features);
 165                 if (err) {
 166                         kfree_skb_list(segs);
 167                         return ERR_PTR(err);
 168                 }
 169
 170                 if (!skb_is_gso(skb2))
 171                         seq++;
 172                 else
 173                         seq += skb_shinfo(skb2)->gso_segs;
 174
 175                 skb_push(skb2, skb2->mac_len);
 176                 skb2 = nskb;
 177         } while (skb2);
 178
 179 out:
 180         return segs;
 181 }
 182
 183 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
 184 {
 185         struct crypto_aead *aead = x->data;
 186         struct xfrm_offload *xo = xfrm_offload(skb);
 187
 188         if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
 189                 return -EINVAL;
 190
 191         if (!(xo->flags & CRYPTO_DONE))
 192                 skb->ip_summed = CHECKSUM_NONE;
 193
 194         return esp_input_done2(skb, 0);
 195 }
 196
 197 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
 198 {
 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
 208         esp.inplace = true;
 209
 210         xo = xfrm_offload(skb);
 211
 212         if (!xo)
 213                 return -EINVAL;
 214
 215         if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
 216             (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         esp.esph = ip_esp_hdr(skb);
 237
 238
 239         if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
 240                 esp.nfrags = esp_output_head(x, skb, &esp);
 241                 if (esp.nfrags < 0)
 242                         return esp.nfrags;
 243         }
 244
 245         esph = esp.esph;
 246         esph->spi = x->id.spi;
 247
 248         skb_push(skb, -skb_network_offset(skb));
 249
 250         if (xo->flags & XFRM_GSO_SEGMENT) {
 251                 esph->seq_no = htonl(xo->seq.low);
 252         } else {
 253                 ip_hdr(skb)->tot_len = htons(skb->len);
 254                 ip_send_check(ip_hdr(skb));
 255         }
 256
 257         if (hw_offload)
 258                 return 0;
 259
 260         esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
 261
 262         err = esp_output_tail(x, skb, &esp);
 263         if (err)
 264                 return err;
 265
 266         secpath_reset(skb);
 267
 268         return 0;
 269 }
 270
 271 static const struct net_offload esp4_offload = {
 272         .callbacks = {
 273                 .gro_receive = esp4_gro_receive,
 274                 .gso_segment = esp4_gso_segment,
 275         },
 276 };
 277
 278 static const struct xfrm_type_offload esp_type_offload = {
 279         .description    = "ESP4 OFFLOAD",
 280         .owner          = THIS_MODULE,
 281         .proto          = IPPROTO_ESP,
 282         .input_tail     = esp_input_tail,
 283         .xmit           = esp_xmit,
 284         .encap          = esp4_gso_encap,
 285 };
 286
 287 static int __init esp4_offload_init(void)
 288 {
 289         if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
 290                 pr_info("%s: can't add xfrm type offload\n", __func__);
 291                 return -EAGAIN;
 292         }
 293
 294         return inet_add_offload(&esp4_offload, IPPROTO_ESP);
 295 }
 296
 297 static void __exit esp4_offload_exit(void)
 298 {
 299         if (xfrm_unregister_type_offload(&esp_type_offload, AF_INET) < 0)
 300                 pr_info("%s: can't remove xfrm type offload\n", __func__);
 301
 302         inet_del_offload(&esp4_offload, IPPROTO_ESP);
 303 }
 304
 305 module_init(esp4_offload_init);
 306 module_exit(esp4_offload_exit);
 307 MODULE_LICENSE("GPL");
 308 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 309 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);