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         struct xfrm_state *x;
 113         struct ip_esp_hdr *esph;
 114         struct crypto_aead *aead;
 115         netdev_features_t esp_features = features;
 116         struct xfrm_offload *xo = xfrm_offload(skb);
 117
 118         if (!xo)
 119                 return ERR_PTR(-EINVAL);
 120
 121         if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
 122                 return ERR_PTR(-EINVAL);
 123
 124         x = skb->sp->xvec[skb->sp->len - 1];
 125         aead = x->data;
 126         esph = ip_esp_hdr(skb);
 127
 128         if (esph->spi != x->id.spi)
 129                 return ERR_PTR(-EINVAL);
 130
 131         if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
 132                 return ERR_PTR(-EINVAL);
 133
 134         __skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
 135
 136         skb->encap_hdr_csum = 1;
 137
 138         if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
 139             (x->xso.dev != skb->dev))
 140                 esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
 141         else if (!(features & NETIF_F_HW_ESP_TX_CSUM))
 142                 esp_features = features & ~NETIF_F_CSUM_MASK;
 143
 144         xo->flags |= XFRM_GSO_SEGMENT;
 145
 146         return x->outer_mode->gso_segment(x, skb, esp_features);
 147 }
 148
 149 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
 150 {
 151         struct crypto_aead *aead = x->data;
 152         struct xfrm_offload *xo = xfrm_offload(skb);
 153
 154         if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
 155                 return -EINVAL;
 156
 157         if (!(xo->flags & CRYPTO_DONE))
 158                 skb->ip_summed = CHECKSUM_NONE;
 159
 160         return esp_input_done2(skb, 0);
 161 }
 162
 163 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
 164 {
 165         int err;
 166         int alen;
 167         int blksize;
 168         struct xfrm_offload *xo;
 169         struct ip_esp_hdr *esph;
 170         struct crypto_aead *aead;
 171         struct esp_info esp;
 172         bool hw_offload = true;
 173         __u32 seq;
 174
 175         esp.inplace = true;
 176
 177         xo = xfrm_offload(skb);
 178
 179         if (!xo)
 180                 return -EINVAL;
 181
 182         if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
 183             (x->xso.dev != skb->dev)) {
 184                 xo->flags |= CRYPTO_FALLBACK;
 185                 hw_offload = false;
 186         }
 187
 188         esp.proto = xo->proto;
 189
 190         /* skb is pure payload to encrypt */
 191
 192         aead = x->data;
 193         alen = crypto_aead_authsize(aead);
 194
 195         esp.tfclen = 0;
 196         /* XXX: Add support for tfc padding here. */
 197
 198         blksize = ALIGN(crypto_aead_blocksize(aead), 4);
 199         esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
 200         esp.plen = esp.clen - skb->len - esp.tfclen;
 201         esp.tailen = esp.tfclen + esp.plen + alen;
 202
 203         esp.esph = ip_esp_hdr(skb);
 204
 205
 206         if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
 207                 esp.nfrags = esp_output_head(x, skb, &esp);
 208                 if (esp.nfrags < 0)
 209                         return esp.nfrags;
 210         }
 211
 212         seq = xo->seq.low;
 213
 214         esph = esp.esph;
 215         esph->spi = x->id.spi;
 216
 217         skb_push(skb, -skb_network_offset(skb));
 218
 219         if (xo->flags & XFRM_GSO_SEGMENT) {
 220                 esph->seq_no = htonl(seq);
 221
 222                 if (!skb_is_gso(skb))
 223                         xo->seq.low++;
 224                 else
 225                         xo->seq.low += skb_shinfo(skb)->gso_segs;
 226         }
 227
 228         esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
 229
 230         ip_hdr(skb)->tot_len = htons(skb->len);
 231         ip_send_check(ip_hdr(skb));
 232
 233         if (hw_offload)
 234                 return 0;
 235
 236         err = esp_output_tail(x, skb, &esp);
 237         if (err)
 238                 return err;
 239
 240         secpath_reset(skb);
 241
 242         return 0;
 243 }
 244
 245 static const struct net_offload esp4_offload = {
 246         .callbacks = {
 247                 .gro_receive = esp4_gro_receive,
 248                 .gso_segment = esp4_gso_segment,
 249         },
 250 };
 251
 252 static const struct xfrm_type_offload esp_type_offload = {
 253         .description    = "ESP4 OFFLOAD",
 254         .owner          = THIS_MODULE,
 255         .proto          = IPPROTO_ESP,
 256         .input_tail     = esp_input_tail,
 257         .xmit           = esp_xmit,
 258         .encap          = esp4_gso_encap,
 259 };
 260
 261 static int __init esp4_offload_init(void)
 262 {
 263         if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
 264                 pr_info("%s: can't add xfrm type offload\n", __func__);
 265                 return -EAGAIN;
 266         }
 267
 268         return inet_add_offload(&esp4_offload, IPPROTO_ESP);
 269 }
 270
 271 static void __exit esp4_offload_exit(void)
 272 {
 273         if (xfrm_unregister_type_offload(&esp_type_offload, AF_INET) < 0)
 274                 pr_info("%s: can't remove xfrm type offload\n", __func__);
 275
 276         inet_del_offload(&esp4_offload, IPPROTO_ESP);
 277 }
 278
 279 module_init(esp4_offload_init);
 280 module_exit(esp4_offload_exit);
 281 MODULE_LICENSE("GPL");
 282 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 283 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);