net/netfilter/nft_payload.c

   1 /*
   2  * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * Development of this code funded by Astaro AG (http://www.astaro.com/)
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/if_vlan.h>
  13 #include <linux/init.h>
  14 #include <linux/module.h>
  15 #include <linux/netlink.h>
  16 #include <linux/netfilter.h>
  17 #include <linux/netfilter/nf_tables.h>
  18 #include <net/netfilter/nf_tables_core.h>
  19 #include <net/netfilter/nf_tables.h>
  20
  21 /* add vlan header into the user buffer for if tag was removed by offloads */
  22 static bool
  23 nft_payload_copy_vlan(u32 *d, const struct sk_buff *skb, u8 offset, u8 len)
  24 {
  25         int mac_off = skb_mac_header(skb) - skb->data;
  26         u8 vlan_len, *vlanh, *dst_u8 = (u8 *) d;
  27         struct vlan_ethhdr veth;
  28
  29         vlanh = (u8 *) &veth;
  30         if (offset < ETH_HLEN) {
  31                 u8 ethlen = min_t(u8, len, ETH_HLEN - offset);
  32
  33                 if (skb_copy_bits(skb, mac_off, &veth, ETH_HLEN))
  34                         return false;
  35
  36                 veth.h_vlan_proto = skb->vlan_proto;
  37
  38                 memcpy(dst_u8, vlanh + offset, ethlen);
  39
  40                 len -= ethlen;
  41                 if (len == 0)
  42                         return true;
  43
  44                 dst_u8 += ethlen;
  45                 offset = ETH_HLEN;
  46         } else if (offset >= VLAN_ETH_HLEN) {
  47                 offset -= VLAN_HLEN;
  48                 goto skip;
  49         }
  50
  51         veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
  52         veth.h_vlan_encapsulated_proto = skb->protocol;
  53
  54         vlanh += offset;
  55
  56         vlan_len = min_t(u8, len, VLAN_ETH_HLEN - offset);
  57         memcpy(dst_u8, vlanh, vlan_len);
  58
  59         len -= vlan_len;
  60         if (!len)
  61                 return true;
  62
  63         dst_u8 += vlan_len;
  64  skip:
  65         return skb_copy_bits(skb, offset + mac_off, dst_u8, len) == 0;
  66 }
  67
  68 static void nft_payload_eval(const struct nft_expr *expr,
  69                              struct nft_regs *regs,
  70                              const struct nft_pktinfo *pkt)
  71 {
  72         const struct nft_payload *priv = nft_expr_priv(expr);
  73         const struct sk_buff *skb = pkt->skb;
  74         u32 *dest = &regs->data[priv->dreg];
  75         int offset;
  76
  77         dest[priv->len / NFT_REG32_SIZE] = 0;
  78         switch (priv->base) {
  79         case NFT_PAYLOAD_LL_HEADER:
  80                 if (!skb_mac_header_was_set(skb))
  81                         goto err;
  82
  83                 if (skb_vlan_tag_present(skb)) {
  84                         if (!nft_payload_copy_vlan(dest, skb,
  85                                                    priv->offset, priv->len))
  86                                 goto err;
  87                         return;
  88                 }
  89                 offset = skb_mac_header(skb) - skb->data;
  90                 break;
  91         case NFT_PAYLOAD_NETWORK_HEADER:
  92                 offset = skb_network_offset(skb);
  93                 break;
  94         case NFT_PAYLOAD_TRANSPORT_HEADER:
  95                 if (!pkt->tprot_set)
  96                         goto err;
  97                 offset = pkt->xt.thoff;
  98                 break;
  99         default:
 100                 BUG();
 101         }
 102         offset += priv->offset;
 103
 104         if (skb_copy_bits(skb, offset, dest, priv->len) < 0)
 105                 goto err;
 106         return;
 107 err:
 108         regs->verdict.code = NFT_BREAK;
 109 }
 110
 111 static const struct nla_policy nft_payload_policy[NFTA_PAYLOAD_MAX + 1] = {
 112         [NFTA_PAYLOAD_SREG]             = { .type = NLA_U32 },
 113         [NFTA_PAYLOAD_DREG]             = { .type = NLA_U32 },
 114         [NFTA_PAYLOAD_BASE]             = { .type = NLA_U32 },
 115         [NFTA_PAYLOAD_OFFSET]           = { .type = NLA_U32 },
 116         [NFTA_PAYLOAD_LEN]              = { .type = NLA_U32 },
 117         [NFTA_PAYLOAD_CSUM_TYPE]        = { .type = NLA_U32 },
 118         [NFTA_PAYLOAD_CSUM_OFFSET]      = { .type = NLA_U32 },
 119 };
 120
 121 static int nft_payload_init(const struct nft_ctx *ctx,
 122                             const struct nft_expr *expr,
 123                             const struct nlattr * const tb[])
 124 {
 125         struct nft_payload *priv = nft_expr_priv(expr);
 126
 127         priv->base   = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 128         priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
 129         priv->len    = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
 130         priv->dreg   = nft_parse_register(tb[NFTA_PAYLOAD_DREG]);
 131
 132         return nft_validate_register_store(ctx, priv->dreg, NULL,
 133                                            NFT_DATA_VALUE, priv->len);
 134 }
 135
 136 static int nft_payload_dump(struct sk_buff *skb, const struct nft_expr *expr)
 137 {
 138         const struct nft_payload *priv = nft_expr_priv(expr);
 139
 140         if (nft_dump_register(skb, NFTA_PAYLOAD_DREG, priv->dreg) ||
 141             nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
 142             nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
 143             nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)))
 144                 goto nla_put_failure;
 145         return 0;
 146
 147 nla_put_failure:
 148         return -1;
 149 }
 150
 151 static struct nft_expr_type nft_payload_type;
 152 static const struct nft_expr_ops nft_payload_ops = {
 153         .type           = &nft_payload_type,
 154         .size           = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
 155         .eval           = nft_payload_eval,
 156         .init           = nft_payload_init,
 157         .dump           = nft_payload_dump,
 158 };
 159
 160 const struct nft_expr_ops nft_payload_fast_ops = {
 161         .type           = &nft_payload_type,
 162         .size           = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
 163         .eval           = nft_payload_eval,
 164         .init           = nft_payload_init,
 165         .dump           = nft_payload_dump,
 166 };
 167
 168 static void nft_payload_set_eval(const struct nft_expr *expr,
 169                                  struct nft_regs *regs,
 170                                  const struct nft_pktinfo *pkt)
 171 {
 172         const struct nft_payload_set *priv = nft_expr_priv(expr);
 173         struct sk_buff *skb = pkt->skb;
 174         const u32 *src = &regs->data[priv->sreg];
 175         int offset, csum_offset;
 176         __wsum fsum, tsum;
 177         __sum16 sum;
 178
 179         switch (priv->base) {
 180         case NFT_PAYLOAD_LL_HEADER:
 181                 if (!skb_mac_header_was_set(skb))
 182                         goto err;
 183                 offset = skb_mac_header(skb) - skb->data;
 184                 break;
 185         case NFT_PAYLOAD_NETWORK_HEADER:
 186                 offset = skb_network_offset(skb);
 187                 break;
 188         case NFT_PAYLOAD_TRANSPORT_HEADER:
 189                 if (!pkt->tprot_set)
 190                         goto err;
 191                 offset = pkt->xt.thoff;
 192                 break;
 193         default:
 194                 BUG();
 195         }
 196
 197         csum_offset = offset + priv->csum_offset;
 198         offset += priv->offset;
 199
 200         if (priv->csum_type == NFT_PAYLOAD_CSUM_INET &&
 201             (priv->base != NFT_PAYLOAD_TRANSPORT_HEADER ||
 202              skb->ip_summed != CHECKSUM_PARTIAL)) {
 203                 if (skb_copy_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
 204                         goto err;
 205
 206                 fsum = skb_checksum(skb, offset, priv->len, 0);
 207                 tsum = csum_partial(src, priv->len, 0);
 208                 sum = csum_fold(csum_add(csum_sub(~csum_unfold(sum), fsum),
 209                                          tsum));
 210                 if (sum == 0)
 211                         sum = CSUM_MANGLED_0;
 212
 213                 if (!skb_make_writable(skb, csum_offset + sizeof(sum)) ||
 214                     skb_store_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
 215                         goto err;
 216         }
 217
 218         if (!skb_make_writable(skb, max(offset + priv->len, 0)) ||
 219             skb_store_bits(skb, offset, src, priv->len) < 0)
 220                 goto err;
 221
 222         return;
 223 err:
 224         regs->verdict.code = NFT_BREAK;
 225 }
 226
 227 static int nft_payload_set_init(const struct nft_ctx *ctx,
 228                                 const struct nft_expr *expr,
 229                                 const struct nlattr * const tb[])
 230 {
 231         struct nft_payload_set *priv = nft_expr_priv(expr);
 232
 233         priv->base        = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 234         priv->offset      = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
 235         priv->len         = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
 236         priv->sreg        = nft_parse_register(tb[NFTA_PAYLOAD_SREG]);
 237
 238         if (tb[NFTA_PAYLOAD_CSUM_TYPE])
 239                 priv->csum_type =
 240                         ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_TYPE]));
 241         if (tb[NFTA_PAYLOAD_CSUM_OFFSET])
 242                 priv->csum_offset =
 243                         ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_OFFSET]));
 244
 245         switch (priv->csum_type) {
 246         case NFT_PAYLOAD_CSUM_NONE:
 247         case NFT_PAYLOAD_CSUM_INET:
 248                 break;
 249         default:
 250                 return -EOPNOTSUPP;
 251         }
 252
 253         return nft_validate_register_load(priv->sreg, priv->len);
 254 }
 255
 256 static int nft_payload_set_dump(struct sk_buff *skb, const struct nft_expr *expr)
 257 {
 258         const struct nft_payload_set *priv = nft_expr_priv(expr);
 259
 260         if (nft_dump_register(skb, NFTA_PAYLOAD_SREG, priv->sreg) ||
 261             nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
 262             nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
 263             nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)) ||
 264             nla_put_be32(skb, NFTA_PAYLOAD_CSUM_TYPE, htonl(priv->csum_type)) ||
 265             nla_put_be32(skb, NFTA_PAYLOAD_CSUM_OFFSET,
 266                          htonl(priv->csum_offset)))
 267                 goto nla_put_failure;
 268         return 0;
 269
 270 nla_put_failure:
 271         return -1;
 272 }
 273
 274 static const struct nft_expr_ops nft_payload_set_ops = {
 275         .type           = &nft_payload_type,
 276         .size           = NFT_EXPR_SIZE(sizeof(struct nft_payload_set)),
 277         .eval           = nft_payload_set_eval,
 278         .init           = nft_payload_set_init,
 279         .dump           = nft_payload_set_dump,
 280 };
 281
 282 static const struct nft_expr_ops *
 283 nft_payload_select_ops(const struct nft_ctx *ctx,
 284                        const struct nlattr * const tb[])
 285 {
 286         enum nft_payload_bases base;
 287         unsigned int offset, len;
 288
 289         if (tb[NFTA_PAYLOAD_BASE] == NULL ||
 290             tb[NFTA_PAYLOAD_OFFSET] == NULL ||
 291             tb[NFTA_PAYLOAD_LEN] == NULL)
 292                 return ERR_PTR(-EINVAL);
 293
 294         base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 295         switch (base) {
 296         case NFT_PAYLOAD_LL_HEADER:
 297         case NFT_PAYLOAD_NETWORK_HEADER:
 298         case NFT_PAYLOAD_TRANSPORT_HEADER:
 299                 break;
 300         default:
 301                 return ERR_PTR(-EOPNOTSUPP);
 302         }
 303
 304         if (tb[NFTA_PAYLOAD_SREG] != NULL) {
 305                 if (tb[NFTA_PAYLOAD_DREG] != NULL)
 306                         return ERR_PTR(-EINVAL);
 307                 return &nft_payload_set_ops;
 308         }
 309
 310         if (tb[NFTA_PAYLOAD_DREG] == NULL)
 311                 return ERR_PTR(-EINVAL);
 312
 313         offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
 314         len    = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
 315
 316         if (len <= 4 && is_power_of_2(len) && IS_ALIGNED(offset, len) &&
 317             base != NFT_PAYLOAD_LL_HEADER)
 318                 return &nft_payload_fast_ops;
 319         else
 320                 return &nft_payload_ops;
 321 }
 322
 323 static struct nft_expr_type nft_payload_type __read_mostly = {
 324         .name           = "payload",
 325         .select_ops     = nft_payload_select_ops,
 326         .policy         = nft_payload_policy,
 327         .maxattr        = NFTA_PAYLOAD_MAX,
 328         .owner          = THIS_MODULE,
 329 };
 330
 331 int __init nft_payload_module_init(void)
 332 {
 333         return nft_register_expr(&nft_payload_type);
 334 }
 335
 336 void nft_payload_module_exit(void)
 337 {
 338         nft_unregister_expr(&nft_payload_type);
 339 }