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                 offset = pkt->xt.thoff;
  96                 break;
  97         default:
  98                 BUG();
  99         }
 100         offset += priv->offset;
 101
 102         if (skb_copy_bits(skb, offset, dest, priv->len) < 0)
 103                 goto err;
 104         return;
 105 err:
 106         regs->verdict.code = NFT_BREAK;
 107 }
 108
 109 static const struct nla_policy nft_payload_policy[NFTA_PAYLOAD_MAX + 1] = {
 110         [NFTA_PAYLOAD_SREG]             = { .type = NLA_U32 },
 111         [NFTA_PAYLOAD_DREG]             = { .type = NLA_U32 },
 112         [NFTA_PAYLOAD_BASE]             = { .type = NLA_U32 },
 113         [NFTA_PAYLOAD_OFFSET]           = { .type = NLA_U32 },
 114         [NFTA_PAYLOAD_LEN]              = { .type = NLA_U32 },
 115         [NFTA_PAYLOAD_CSUM_TYPE]        = { .type = NLA_U32 },
 116         [NFTA_PAYLOAD_CSUM_OFFSET]      = { .type = NLA_U32 },
 117 };
 118
 119 static int nft_payload_init(const struct nft_ctx *ctx,
 120                             const struct nft_expr *expr,
 121                             const struct nlattr * const tb[])
 122 {
 123         struct nft_payload *priv = nft_expr_priv(expr);
 124
 125         priv->base   = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 126         priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
 127         priv->len    = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
 128         priv->dreg   = nft_parse_register(tb[NFTA_PAYLOAD_DREG]);
 129
 130         return nft_validate_register_store(ctx, priv->dreg, NULL,
 131                                            NFT_DATA_VALUE, priv->len);
 132 }
 133
 134 static int nft_payload_dump(struct sk_buff *skb, const struct nft_expr *expr)
 135 {
 136         const struct nft_payload *priv = nft_expr_priv(expr);
 137
 138         if (nft_dump_register(skb, NFTA_PAYLOAD_DREG, priv->dreg) ||
 139             nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
 140             nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
 141             nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)))
 142                 goto nla_put_failure;
 143         return 0;
 144
 145 nla_put_failure:
 146         return -1;
 147 }
 148
 149 static struct nft_expr_type nft_payload_type;
 150 static const struct nft_expr_ops nft_payload_ops = {
 151         .type           = &nft_payload_type,
 152         .size           = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
 153         .eval           = nft_payload_eval,
 154         .init           = nft_payload_init,
 155         .dump           = nft_payload_dump,
 156 };
 157
 158 const struct nft_expr_ops nft_payload_fast_ops = {
 159         .type           = &nft_payload_type,
 160         .size           = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
 161         .eval           = nft_payload_eval,
 162         .init           = nft_payload_init,
 163         .dump           = nft_payload_dump,
 164 };
 165
 166 static void nft_payload_set_eval(const struct nft_expr *expr,
 167                                  struct nft_regs *regs,
 168                                  const struct nft_pktinfo *pkt)
 169 {
 170         const struct nft_payload_set *priv = nft_expr_priv(expr);
 171         struct sk_buff *skb = pkt->skb;
 172         const u32 *src = &regs->data[priv->sreg];
 173         int offset, csum_offset;
 174         __wsum fsum, tsum;
 175         __sum16 sum;
 176
 177         switch (priv->base) {
 178         case NFT_PAYLOAD_LL_HEADER:
 179                 if (!skb_mac_header_was_set(skb))
 180                         goto err;
 181                 offset = skb_mac_header(skb) - skb->data;
 182                 break;
 183         case NFT_PAYLOAD_NETWORK_HEADER:
 184                 offset = skb_network_offset(skb);
 185                 break;
 186         case NFT_PAYLOAD_TRANSPORT_HEADER:
 187                 offset = pkt->xt.thoff;
 188                 break;
 189         default:
 190                 BUG();
 191         }
 192
 193         csum_offset = offset + priv->csum_offset;
 194         offset += priv->offset;
 195
 196         if (priv->csum_type == NFT_PAYLOAD_CSUM_INET &&
 197             (priv->base != NFT_PAYLOAD_TRANSPORT_HEADER ||
 198              skb->ip_summed != CHECKSUM_PARTIAL)) {
 199                 if (skb_copy_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
 200                         goto err;
 201
 202                 fsum = skb_checksum(skb, offset, priv->len, 0);
 203                 tsum = csum_partial(src, priv->len, 0);
 204                 sum = csum_fold(csum_add(csum_sub(~csum_unfold(sum), fsum),
 205                                          tsum));
 206                 if (sum == 0)
 207                         sum = CSUM_MANGLED_0;
 208
 209                 if (!skb_make_writable(skb, csum_offset + sizeof(sum)) ||
 210                     skb_store_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
 211                         goto err;
 212         }
 213
 214         if (!skb_make_writable(skb, max(offset + priv->len, 0)) ||
 215             skb_store_bits(skb, offset, src, priv->len) < 0)
 216                 goto err;
 217
 218         return;
 219 err:
 220         regs->verdict.code = NFT_BREAK;
 221 }
 222
 223 static int nft_payload_set_init(const struct nft_ctx *ctx,
 224                                 const struct nft_expr *expr,
 225                                 const struct nlattr * const tb[])
 226 {
 227         struct nft_payload_set *priv = nft_expr_priv(expr);
 228
 229         priv->base        = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 230         priv->offset      = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
 231         priv->len         = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
 232         priv->sreg        = nft_parse_register(tb[NFTA_PAYLOAD_SREG]);
 233
 234         if (tb[NFTA_PAYLOAD_CSUM_TYPE])
 235                 priv->csum_type =
 236                         ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_TYPE]));
 237         if (tb[NFTA_PAYLOAD_CSUM_OFFSET])
 238                 priv->csum_offset =
 239                         ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_OFFSET]));
 240
 241         switch (priv->csum_type) {
 242         case NFT_PAYLOAD_CSUM_NONE:
 243         case NFT_PAYLOAD_CSUM_INET:
 244                 break;
 245         default:
 246                 return -EOPNOTSUPP;
 247         }
 248
 249         return nft_validate_register_load(priv->sreg, priv->len);
 250 }
 251
 252 static int nft_payload_set_dump(struct sk_buff *skb, const struct nft_expr *expr)
 253 {
 254         const struct nft_payload_set *priv = nft_expr_priv(expr);
 255
 256         if (nft_dump_register(skb, NFTA_PAYLOAD_SREG, priv->sreg) ||
 257             nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
 258             nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
 259             nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)) ||
 260             nla_put_be32(skb, NFTA_PAYLOAD_CSUM_TYPE, htonl(priv->csum_type)) ||
 261             nla_put_be32(skb, NFTA_PAYLOAD_CSUM_OFFSET,
 262                          htonl(priv->csum_offset)))
 263                 goto nla_put_failure;
 264         return 0;
 265
 266 nla_put_failure:
 267         return -1;
 268 }
 269
 270 static const struct nft_expr_ops nft_payload_set_ops = {
 271         .type           = &nft_payload_type,
 272         .size           = NFT_EXPR_SIZE(sizeof(struct nft_payload_set)),
 273         .eval           = nft_payload_set_eval,
 274         .init           = nft_payload_set_init,
 275         .dump           = nft_payload_set_dump,
 276 };
 277
 278 static const struct nft_expr_ops *
 279 nft_payload_select_ops(const struct nft_ctx *ctx,
 280                        const struct nlattr * const tb[])
 281 {
 282         enum nft_payload_bases base;
 283         unsigned int offset, len;
 284
 285         if (tb[NFTA_PAYLOAD_BASE] == NULL ||
 286             tb[NFTA_PAYLOAD_OFFSET] == NULL ||
 287             tb[NFTA_PAYLOAD_LEN] == NULL)
 288                 return ERR_PTR(-EINVAL);
 289
 290         base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 291         switch (base) {
 292         case NFT_PAYLOAD_LL_HEADER:
 293         case NFT_PAYLOAD_NETWORK_HEADER:
 294         case NFT_PAYLOAD_TRANSPORT_HEADER:
 295                 break;
 296         default:
 297                 return ERR_PTR(-EOPNOTSUPP);
 298         }
 299
 300         if (tb[NFTA_PAYLOAD_SREG] != NULL) {
 301                 if (tb[NFTA_PAYLOAD_DREG] != NULL)
 302                         return ERR_PTR(-EINVAL);
 303                 return &nft_payload_set_ops;
 304         }
 305
 306         if (tb[NFTA_PAYLOAD_DREG] == NULL)
 307                 return ERR_PTR(-EINVAL);
 308
 309         offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
 310         len    = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
 311
 312         if (len <= 4 && is_power_of_2(len) && IS_ALIGNED(offset, len) &&
 313             base != NFT_PAYLOAD_LL_HEADER)
 314                 return &nft_payload_fast_ops;
 315         else
 316                 return &nft_payload_ops;
 317 }
 318
 319 static struct nft_expr_type nft_payload_type __read_mostly = {
 320         .name           = "payload",
 321         .select_ops     = nft_payload_select_ops,
 322         .policy         = nft_payload_policy,
 323         .maxattr        = NFTA_PAYLOAD_MAX,
 324         .owner          = THIS_MODULE,
 325 };
 326
 327 int __init nft_payload_module_init(void)
 328 {
 329         return nft_register_expr(&nft_payload_type);
 330 }
 331
 332 void nft_payload_module_exit(void)
 333 {
 334         nft_unregister_expr(&nft_payload_type);
 335 }