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 const struct nft_expr_ops nft_payload_ops = {
 152         .type           = &nft_payload_type,
 153         .size           = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
 154         .eval           = nft_payload_eval,
 155         .init           = nft_payload_init,
 156         .dump           = nft_payload_dump,
 157 };
 158
 159 const struct nft_expr_ops nft_payload_fast_ops = {
 160         .type           = &nft_payload_type,
 161         .size           = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
 162         .eval           = nft_payload_eval,
 163         .init           = nft_payload_init,
 164         .dump           = nft_payload_dump,
 165 };
 166
 167 static void nft_payload_set_eval(const struct nft_expr *expr,
 168                                  struct nft_regs *regs,
 169                                  const struct nft_pktinfo *pkt)
 170 {
 171         const struct nft_payload_set *priv = nft_expr_priv(expr);
 172         struct sk_buff *skb = pkt->skb;
 173         const u32 *src = &regs->data[priv->sreg];
 174         int offset, csum_offset;
 175         __wsum fsum, tsum;
 176         __sum16 sum;
 177
 178         switch (priv->base) {
 179         case NFT_PAYLOAD_LL_HEADER:
 180                 if (!skb_mac_header_was_set(skb))
 181                         goto err;
 182                 offset = skb_mac_header(skb) - skb->data;
 183                 break;
 184         case NFT_PAYLOAD_NETWORK_HEADER:
 185                 offset = skb_network_offset(skb);
 186                 break;
 187         case NFT_PAYLOAD_TRANSPORT_HEADER:
 188                 if (!pkt->tprot_set)
 189                         goto err;
 190                 offset = pkt->xt.thoff;
 191                 break;
 192         default:
 193                 BUG();
 194         }
 195
 196         csum_offset = offset + priv->csum_offset;
 197         offset += priv->offset;
 198
 199         if (priv->csum_type == NFT_PAYLOAD_CSUM_INET &&
 200             (priv->base != NFT_PAYLOAD_TRANSPORT_HEADER ||
 201              skb->ip_summed != CHECKSUM_PARTIAL)) {
 202                 if (skb_copy_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
 203                         goto err;
 204
 205                 fsum = skb_checksum(skb, offset, priv->len, 0);
 206                 tsum = csum_partial(src, priv->len, 0);
 207                 sum = csum_fold(csum_add(csum_sub(~csum_unfold(sum), fsum),
 208                                          tsum));
 209                 if (sum == 0)
 210                         sum = CSUM_MANGLED_0;
 211
 212                 if (!skb_make_writable(skb, csum_offset + sizeof(sum)) ||
 213                     skb_store_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
 214                         goto err;
 215         }
 216
 217         if (!skb_make_writable(skb, max(offset + priv->len, 0)) ||
 218             skb_store_bits(skb, offset, src, priv->len) < 0)
 219                 goto err;
 220
 221         return;
 222 err:
 223         regs->verdict.code = NFT_BREAK;
 224 }
 225
 226 static int nft_payload_set_init(const struct nft_ctx *ctx,
 227                                 const struct nft_expr *expr,
 228                                 const struct nlattr * const tb[])
 229 {
 230         struct nft_payload_set *priv = nft_expr_priv(expr);
 231
 232         priv->base        = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 233         priv->offset      = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
 234         priv->len         = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
 235         priv->sreg        = nft_parse_register(tb[NFTA_PAYLOAD_SREG]);
 236
 237         if (tb[NFTA_PAYLOAD_CSUM_TYPE])
 238                 priv->csum_type =
 239                         ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_TYPE]));
 240         if (tb[NFTA_PAYLOAD_CSUM_OFFSET])
 241                 priv->csum_offset =
 242                         ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_OFFSET]));
 243
 244         switch (priv->csum_type) {
 245         case NFT_PAYLOAD_CSUM_NONE:
 246         case NFT_PAYLOAD_CSUM_INET:
 247                 break;
 248         default:
 249                 return -EOPNOTSUPP;
 250         }
 251
 252         return nft_validate_register_load(priv->sreg, priv->len);
 253 }
 254
 255 static int nft_payload_set_dump(struct sk_buff *skb, const struct nft_expr *expr)
 256 {
 257         const struct nft_payload_set *priv = nft_expr_priv(expr);
 258
 259         if (nft_dump_register(skb, NFTA_PAYLOAD_SREG, priv->sreg) ||
 260             nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
 261             nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
 262             nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)) ||
 263             nla_put_be32(skb, NFTA_PAYLOAD_CSUM_TYPE, htonl(priv->csum_type)) ||
 264             nla_put_be32(skb, NFTA_PAYLOAD_CSUM_OFFSET,
 265                          htonl(priv->csum_offset)))
 266                 goto nla_put_failure;
 267         return 0;
 268
 269 nla_put_failure:
 270         return -1;
 271 }
 272
 273 static const struct nft_expr_ops nft_payload_set_ops = {
 274         .type           = &nft_payload_type,
 275         .size           = NFT_EXPR_SIZE(sizeof(struct nft_payload_set)),
 276         .eval           = nft_payload_set_eval,
 277         .init           = nft_payload_set_init,
 278         .dump           = nft_payload_set_dump,
 279 };
 280
 281 static const struct nft_expr_ops *
 282 nft_payload_select_ops(const struct nft_ctx *ctx,
 283                        const struct nlattr * const tb[])
 284 {
 285         enum nft_payload_bases base;
 286         unsigned int offset, len;
 287
 288         if (tb[NFTA_PAYLOAD_BASE] == NULL ||
 289             tb[NFTA_PAYLOAD_OFFSET] == NULL ||
 290             tb[NFTA_PAYLOAD_LEN] == NULL)
 291                 return ERR_PTR(-EINVAL);
 292
 293         base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 294         switch (base) {
 295         case NFT_PAYLOAD_LL_HEADER:
 296         case NFT_PAYLOAD_NETWORK_HEADER:
 297         case NFT_PAYLOAD_TRANSPORT_HEADER:
 298                 break;
 299         default:
 300                 return ERR_PTR(-EOPNOTSUPP);
 301         }
 302
 303         if (tb[NFTA_PAYLOAD_SREG] != NULL) {
 304                 if (tb[NFTA_PAYLOAD_DREG] != NULL)
 305                         return ERR_PTR(-EINVAL);
 306                 return &nft_payload_set_ops;
 307         }
 308
 309         if (tb[NFTA_PAYLOAD_DREG] == NULL)
 310                 return ERR_PTR(-EINVAL);
 311
 312         offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
 313         len    = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
 314
 315         if (len <= 4 && is_power_of_2(len) && IS_ALIGNED(offset, len) &&
 316             base != NFT_PAYLOAD_LL_HEADER)
 317                 return &nft_payload_fast_ops;
 318         else
 319                 return &nft_payload_ops;
 320 }
 321
 322 struct nft_expr_type nft_payload_type __read_mostly = {
 323         .name           = "payload",
 324         .select_ops     = nft_payload_select_ops,
 325         .policy         = nft_payload_policy,
 326         .maxattr        = NFTA_PAYLOAD_MAX,
 327         .owner          = THIS_MODULE,
 328 };