net/ipv4/esp4_offload.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * IPV4 GSO/GRO offload support
   4  * Linux INET implementation
   5  *
   6  * Copyright (C) 2016 secunet Security Networks AG
   7  * Author: Steffen Klassert <steffen.klassert@secunet.com>
   8  *
   9  * ESP GRO support
  10  */
  11
  12 #include <linux/skbuff.h>
  13 #include <linux/init.h>
  14 #include <net/protocol.h>
  15 #include <crypto/aead.h>
  16 #include <crypto/authenc.h>
  17 #include <linux/err.h>
  18 #include <linux/module.h>
  19 #include <net/gro.h>
  20 #include <net/gso.h>
  21 #include <net/ip.h>
  22 #include <net/xfrm.h>
  23 #include <net/esp.h>
  24 #include <linux/scatterlist.h>
  25 #include <linux/kernel.h>
  26 #include <linux/slab.h>
  27 #include <linux/spinlock.h>
  28 #include <net/udp.h>
  29
  30 static struct sk_buff *esp4_gro_receive(struct list_head *head,
  31                                         struct sk_buff *skb)
  32 {
  33         int offset = skb_gro_offset(skb);
  34         struct xfrm_offload *xo;
  35         struct xfrm_state *x;
  36         int encap_type = 0;
  37         __be32 seq;
  38         __be32 spi;
  39
  40         if (!pskb_pull(skb, offset))
  41                 return NULL;
  42
  43         if (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                 struct sec_path *sp = secpath_set(skb);
  49
  50                 if (!sp)
  51                         goto out;
  52
  53                 if (sp->len == XFRM_MAX_DEPTH)
  54                         goto out_reset;
  55
  56                 x = xfrm_input_state_lookup(dev_net(skb->dev), skb->mark,
  57                                             (xfrm_address_t *)&ip_hdr(skb)->daddr,
  58                                             spi, IPPROTO_ESP, AF_INET);
  59
  60                 if (unlikely(x && x->dir && x->dir != XFRM_SA_DIR_IN)) {
  61                         /* non-offload path will record the error and audit log */
  62                         xfrm_state_put(x);
  63                         x = NULL;
  64                 }
  65
  66                 if (!x)
  67                         goto out_reset;
  68
  69                 skb->mark = xfrm_smark_get(skb->mark, x);
  70
  71                 sp->xvec[sp->len++] = x;
  72                 sp->olen++;
  73
  74                 xo = xfrm_offload(skb);
  75                 if (!xo)
  76                         goto out_reset;
  77         }
  78
  79         xo->flags |= XFRM_GRO;
  80
  81         if (NAPI_GRO_CB(skb)->proto == IPPROTO_UDP)
  82                 encap_type = UDP_ENCAP_ESPINUDP;
  83
  84         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
  85         XFRM_SPI_SKB_CB(skb)->family = AF_INET;
  86         XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
  87         XFRM_SPI_SKB_CB(skb)->seq = seq;
  88
  89         /* We don't need to handle errors from xfrm_input, it does all
  90          * the error handling and frees the resources on error. */
  91         xfrm_input(skb, IPPROTO_ESP, spi, encap_type);
  92
  93         return ERR_PTR(-EINPROGRESS);
  94 out_reset:
  95         secpath_reset(skb);
  96 out:
  97         skb_push(skb, offset);
  98         NAPI_GRO_CB(skb)->same_flow = 0;
  99         NAPI_GRO_CB(skb)->flush = 1;
 100
 101         return NULL;
 102 }
 103
 104 static void esp4_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
 105 {
 106         struct ip_esp_hdr *esph;
 107         struct iphdr *iph = ip_hdr(skb);
 108         struct xfrm_offload *xo = xfrm_offload(skb);
 109         int proto = iph->protocol;
 110
 111         skb_push(skb, -skb_network_offset(skb));
 112         esph = ip_esp_hdr(skb);
 113         *skb_mac_header(skb) = IPPROTO_ESP;
 114
 115         esph->spi = x->id.spi;
 116         esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
 117
 118         xo->proto = proto;
 119 }
 120
 121 static struct sk_buff *xfrm4_tunnel_gso_segment(struct xfrm_state *x,
 122                                                 struct sk_buff *skb,
 123                                                 netdev_features_t features)
 124 {
 125         __be16 type = x->inner_mode.family == AF_INET6 ? htons(ETH_P_IPV6)
 126                                                        : htons(ETH_P_IP);
 127
 128         return skb_eth_gso_segment(skb, features, type);
 129 }
 130
 131 static struct sk_buff *xfrm4_transport_gso_segment(struct xfrm_state *x,
 132                                                    struct sk_buff *skb,
 133                                                    netdev_features_t features)
 134 {
 135         const struct net_offload *ops;
 136         struct sk_buff *segs = ERR_PTR(-EINVAL);
 137         struct xfrm_offload *xo = xfrm_offload(skb);
 138
 139         skb->transport_header += x->props.header_len;
 140         ops = rcu_dereference(inet_offloads[xo->proto]);
 141         if (likely(ops && ops->callbacks.gso_segment))
 142                 segs = ops->callbacks.gso_segment(skb, features);
 143
 144         return segs;
 145 }
 146
 147 static struct sk_buff *xfrm4_beet_gso_segment(struct xfrm_state *x,
 148                                               struct sk_buff *skb,
 149                                               netdev_features_t features)
 150 {
 151         struct xfrm_offload *xo = xfrm_offload(skb);
 152         struct sk_buff *segs = ERR_PTR(-EINVAL);
 153         const struct net_offload *ops;
 154         u8 proto = xo->proto;
 155
 156         skb->transport_header += x->props.header_len;
 157
 158         if (x->sel.family != AF_INET6) {
 159                 if (proto == IPPROTO_BEETPH) {
 160                         struct ip_beet_phdr *ph =
 161                                 (struct ip_beet_phdr *)skb->data;
 162
 163                         skb->transport_header += ph->hdrlen * 8;
 164                         proto = ph->nexthdr;
 165                 } else {
 166                         skb->transport_header -= IPV4_BEET_PHMAXLEN;
 167                 }
 168         } else {
 169                 __be16 frag;
 170
 171                 skb->transport_header +=
 172                         ipv6_skip_exthdr(skb, 0, &proto, &frag);
 173                 if (proto == IPPROTO_TCP)
 174                         skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
 175         }
 176
 177         if (proto == IPPROTO_IPV6)
 178                 skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP4;
 179
 180         __skb_pull(skb, skb_transport_offset(skb));
 181         ops = rcu_dereference(inet_offloads[proto]);
 182         if (likely(ops && ops->callbacks.gso_segment))
 183                 segs = ops->callbacks.gso_segment(skb, features);
 184
 185         return segs;
 186 }
 187
 188 static struct sk_buff *xfrm4_outer_mode_gso_segment(struct xfrm_state *x,
 189                                                     struct sk_buff *skb,
 190                                                     netdev_features_t features)
 191 {
 192         switch (x->outer_mode.encap) {
 193         case XFRM_MODE_TUNNEL:
 194                 return xfrm4_tunnel_gso_segment(x, skb, features);
 195         case XFRM_MODE_TRANSPORT:
 196                 return xfrm4_transport_gso_segment(x, skb, features);
 197         case XFRM_MODE_BEET:
 198                 return xfrm4_beet_gso_segment(x, skb, features);
 199         }
 200
 201         return ERR_PTR(-EOPNOTSUPP);
 202 }
 203
 204 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
 205                                         netdev_features_t features)
 206 {
 207         struct xfrm_state *x;
 208         struct ip_esp_hdr *esph;
 209         struct crypto_aead *aead;
 210         netdev_features_t esp_features = features;
 211         struct xfrm_offload *xo = xfrm_offload(skb);
 212         struct sec_path *sp;
 213
 214         if (!xo)
 215                 return ERR_PTR(-EINVAL);
 216
 217         if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
 218                 return ERR_PTR(-EINVAL);
 219
 220         sp = skb_sec_path(skb);
 221         x = sp->xvec[sp->len - 1];
 222         aead = x->data;
 223         esph = ip_esp_hdr(skb);
 224
 225         if (esph->spi != x->id.spi)
 226                 return ERR_PTR(-EINVAL);
 227
 228         if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
 229                 return ERR_PTR(-EINVAL);
 230
 231         __skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
 232
 233         skb->encap_hdr_csum = 1;
 234
 235         if ((!(skb->dev->gso_partial_features & NETIF_F_HW_ESP) &&
 236              !(features & NETIF_F_HW_ESP)) || x->xso.dev != skb->dev)
 237                 esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK |
 238                                             NETIF_F_SCTP_CRC);
 239         else if (!(features & NETIF_F_HW_ESP_TX_CSUM) &&
 240                  !(skb->dev->gso_partial_features & NETIF_F_HW_ESP_TX_CSUM))
 241                 esp_features = features & ~(NETIF_F_CSUM_MASK |
 242                                             NETIF_F_SCTP_CRC);
 243
 244         xo->flags |= XFRM_GSO_SEGMENT;
 245
 246         return xfrm4_outer_mode_gso_segment(x, skb, esp_features);
 247 }
 248
 249 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
 250 {
 251         struct crypto_aead *aead = x->data;
 252         struct xfrm_offload *xo = xfrm_offload(skb);
 253
 254         if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
 255                 return -EINVAL;
 256
 257         if (!(xo->flags & CRYPTO_DONE))
 258                 skb->ip_summed = CHECKSUM_NONE;
 259
 260         return esp_input_done2(skb, 0);
 261 }
 262
 263 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
 264 {
 265         int err;
 266         int alen;
 267         int blksize;
 268         struct xfrm_offload *xo;
 269         struct ip_esp_hdr *esph;
 270         struct crypto_aead *aead;
 271         struct esp_info esp;
 272         bool hw_offload = true;
 273         __u32 seq;
 274         int encap_type = 0;
 275
 276         esp.inplace = true;
 277
 278         xo = xfrm_offload(skb);
 279
 280         if (!xo)
 281                 return -EINVAL;
 282
 283         if ((!(features & NETIF_F_HW_ESP) &&
 284              !(skb->dev->gso_partial_features & NETIF_F_HW_ESP)) ||
 285             x->xso.dev != skb->dev) {
 286                 xo->flags |= CRYPTO_FALLBACK;
 287                 hw_offload = false;
 288         }
 289
 290         esp.proto = xo->proto;
 291
 292         /* skb is pure payload to encrypt */
 293
 294         aead = x->data;
 295         alen = crypto_aead_authsize(aead);
 296
 297         esp.tfclen = 0;
 298         /* XXX: Add support for tfc padding here. */
 299
 300         blksize = ALIGN(crypto_aead_blocksize(aead), 4);
 301         esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
 302         esp.plen = esp.clen - skb->len - esp.tfclen;
 303         esp.tailen = esp.tfclen + esp.plen + alen;
 304
 305         esp.esph = ip_esp_hdr(skb);
 306
 307         if (x->encap)
 308                 encap_type = x->encap->encap_type;
 309
 310         if (!hw_offload || !skb_is_gso(skb) || (hw_offload && encap_type == UDP_ENCAP_ESPINUDP)) {
 311                 esp.nfrags = esp_output_head(x, skb, &esp);
 312                 if (esp.nfrags < 0)
 313                         return esp.nfrags;
 314         }
 315
 316         seq = xo->seq.low;
 317
 318         esph = esp.esph;
 319         esph->spi = x->id.spi;
 320
 321         skb_push(skb, -skb_network_offset(skb));
 322
 323         if (xo->flags & XFRM_GSO_SEGMENT) {
 324                 esph->seq_no = htonl(seq);
 325
 326                 if (!skb_is_gso(skb))
 327                         xo->seq.low++;
 328                 else
 329                         xo->seq.low += skb_shinfo(skb)->gso_segs;
 330         }
 331
 332         if (xo->seq.low < seq)
 333                 xo->seq.hi++;
 334
 335         esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
 336
 337         if (hw_offload && encap_type == UDP_ENCAP_ESPINUDP) {
 338                 /* In the XFRM stack, the encapsulation protocol is set to iphdr->protocol by
 339                  * setting *skb_mac_header(skb) (see esp_output_udp_encap()) where skb->mac_header
 340                  * points to iphdr->protocol (see xfrm4_tunnel_encap_add()).
 341                  * However, in esp_xmit(), skb->mac_header doesn't point to iphdr->protocol.
 342                  * Therefore, the protocol field needs to be corrected.
 343                  */
 344                 ip_hdr(skb)->protocol = IPPROTO_UDP;
 345
 346                 esph->seq_no = htonl(seq);
 347         }
 348
 349         ip_hdr(skb)->tot_len = htons(skb->len);
 350         ip_send_check(ip_hdr(skb));
 351
 352         if (hw_offload) {
 353                 if (!skb_ext_add(skb, SKB_EXT_SEC_PATH))
 354                         return -ENOMEM;
 355
 356                 xo = xfrm_offload(skb);
 357                 if (!xo)
 358                         return -EINVAL;
 359
 360                 xo->flags |= XFRM_XMIT;
 361                 return 0;
 362         }
 363
 364         err = esp_output_tail(x, skb, &esp);
 365         if (err)
 366                 return err;
 367
 368         secpath_reset(skb);
 369
 370         if (skb_needs_linearize(skb, skb->dev->features) &&
 371             __skb_linearize(skb))
 372                 return -ENOMEM;
 373         return 0;
 374 }
 375
 376 static const struct net_offload esp4_offload = {
 377         .callbacks = {
 378                 .gro_receive = esp4_gro_receive,
 379                 .gso_segment = esp4_gso_segment,
 380         },
 381 };
 382
 383 static const struct xfrm_type_offload esp_type_offload = {
 384         .owner          = THIS_MODULE,
 385         .proto          = IPPROTO_ESP,
 386         .input_tail     = esp_input_tail,
 387         .xmit           = esp_xmit,
 388         .encap          = esp4_gso_encap,
 389 };
 390
 391 static int __init esp4_offload_init(void)
 392 {
 393         if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
 394                 pr_info("%s: can't add xfrm type offload\n", __func__);
 395                 return -EAGAIN;
 396         }
 397
 398         return inet_add_offload(&esp4_offload, IPPROTO_ESP);
 399 }
 400
 401 static void __exit esp4_offload_exit(void)
 402 {
 403         xfrm_unregister_type_offload(&esp_type_offload, AF_INET);
 404         inet_del_offload(&esp4_offload, IPPROTO_ESP);
 405 }
 406
 407 module_init(esp4_offload_init);
 408 module_exit(esp4_offload_exit);
 409 MODULE_LICENSE("GPL");
 410 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 411 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);
 412 MODULE_DESCRIPTION("IPV4 GSO/GRO offload support");