net/netfilter/nft_bitwise.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
   4  *
   5  * Development of this code funded by Astaro AG (http://www.astaro.com/)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/netlink.h>
  12 #include <linux/netfilter.h>
  13 #include <linux/netfilter/nf_tables.h>
  14 #include <net/netfilter/nf_tables_core.h>
  15 #include <net/netfilter/nf_tables.h>
  16 #include <net/netfilter/nf_tables_offload.h>
  17
  18 struct nft_bitwise {
  19         enum nft_registers      sreg:8;
  20         enum nft_registers      dreg:8;
  21         enum nft_bitwise_ops    op:8;
  22         u8                      len;
  23         struct nft_data         mask;
  24         struct nft_data         xor;
  25         struct nft_data         data;
  26 };
  27
  28 static void nft_bitwise_eval_bool(u32 *dst, const u32 *src,
  29                                   const struct nft_bitwise *priv)
  30 {
  31         unsigned int i;
  32
  33         for (i = 0; i < DIV_ROUND_UP(priv->len, 4); i++)
  34                 dst[i] = (src[i] & priv->mask.data[i]) ^ priv->xor.data[i];
  35 }
  36
  37 static void nft_bitwise_eval_lshift(u32 *dst, const u32 *src,
  38                                     const struct nft_bitwise *priv)
  39 {
  40         u32 shift = priv->data.data[0];
  41         unsigned int i;
  42         u32 carry = 0;
  43
  44         for (i = DIV_ROUND_UP(priv->len, sizeof(u32)); i > 0; i--) {
  45                 dst[i - 1] = (src[i - 1] << shift) | carry;
  46                 carry = src[i - 1] >> (BITS_PER_TYPE(u32) - shift);
  47         }
  48 }
  49
  50 static void nft_bitwise_eval_rshift(u32 *dst, const u32 *src,
  51                                     const struct nft_bitwise *priv)
  52 {
  53         u32 shift = priv->data.data[0];
  54         unsigned int i;
  55         u32 carry = 0;
  56
  57         for (i = 0; i < DIV_ROUND_UP(priv->len, sizeof(u32)); i++) {
  58                 dst[i] = carry | (src[i] >> shift);
  59                 carry = src[i] << (BITS_PER_TYPE(u32) - shift);
  60         }
  61 }
  62
  63 void nft_bitwise_eval(const struct nft_expr *expr,
  64                       struct nft_regs *regs, const struct nft_pktinfo *pkt)
  65 {
  66         const struct nft_bitwise *priv = nft_expr_priv(expr);
  67         const u32 *src = &regs->data[priv->sreg];
  68         u32 *dst = &regs->data[priv->dreg];
  69
  70         switch (priv->op) {
  71         case NFT_BITWISE_BOOL:
  72                 nft_bitwise_eval_bool(dst, src, priv);
  73                 break;
  74         case NFT_BITWISE_LSHIFT:
  75                 nft_bitwise_eval_lshift(dst, src, priv);
  76                 break;
  77         case NFT_BITWISE_RSHIFT:
  78                 nft_bitwise_eval_rshift(dst, src, priv);
  79                 break;
  80         }
  81 }
  82
  83 static const struct nla_policy nft_bitwise_policy[NFTA_BITWISE_MAX + 1] = {
  84         [NFTA_BITWISE_SREG]     = { .type = NLA_U32 },
  85         [NFTA_BITWISE_DREG]     = { .type = NLA_U32 },
  86         [NFTA_BITWISE_LEN]      = { .type = NLA_U32 },
  87         [NFTA_BITWISE_MASK]     = { .type = NLA_NESTED },
  88         [NFTA_BITWISE_XOR]      = { .type = NLA_NESTED },
  89         [NFTA_BITWISE_OP]       = { .type = NLA_U32 },
  90         [NFTA_BITWISE_DATA]     = { .type = NLA_NESTED },
  91 };
  92
  93 static int nft_bitwise_init_bool(struct nft_bitwise *priv,
  94                                  const struct nlattr *const tb[])
  95 {
  96         struct nft_data_desc mask, xor;
  97         int err;
  98
  99         if (tb[NFTA_BITWISE_DATA])
 100                 return -EINVAL;
 101
 102         if (!tb[NFTA_BITWISE_MASK] ||
 103             !tb[NFTA_BITWISE_XOR])
 104                 return -EINVAL;
 105
 106         err = nft_data_init(NULL, &priv->mask, sizeof(priv->mask), &mask,
 107                             tb[NFTA_BITWISE_MASK]);
 108         if (err < 0)
 109                 return err;
 110         if (mask.type != NFT_DATA_VALUE || mask.len != priv->len) {
 111                 err = -EINVAL;
 112                 goto err1;
 113         }
 114
 115         err = nft_data_init(NULL, &priv->xor, sizeof(priv->xor), &xor,
 116                             tb[NFTA_BITWISE_XOR]);
 117         if (err < 0)
 118                 goto err1;
 119         if (xor.type != NFT_DATA_VALUE || xor.len != priv->len) {
 120                 err = -EINVAL;
 121                 goto err2;
 122         }
 123
 124         return 0;
 125 err2:
 126         nft_data_release(&priv->xor, xor.type);
 127 err1:
 128         nft_data_release(&priv->mask, mask.type);
 129         return err;
 130 }
 131
 132 static int nft_bitwise_init_shift(struct nft_bitwise *priv,
 133                                   const struct nlattr *const tb[])
 134 {
 135         struct nft_data_desc d;
 136         int err;
 137
 138         if (tb[NFTA_BITWISE_MASK] ||
 139             tb[NFTA_BITWISE_XOR])
 140                 return -EINVAL;
 141
 142         if (!tb[NFTA_BITWISE_DATA])
 143                 return -EINVAL;
 144
 145         err = nft_data_init(NULL, &priv->data, sizeof(priv->data), &d,
 146                             tb[NFTA_BITWISE_DATA]);
 147         if (err < 0)
 148                 return err;
 149         if (d.type != NFT_DATA_VALUE || d.len != sizeof(u32) ||
 150             priv->data.data[0] >= BITS_PER_TYPE(u32)) {
 151                 nft_data_release(&priv->data, d.type);
 152                 return -EINVAL;
 153         }
 154
 155         return 0;
 156 }
 157
 158 static int nft_bitwise_init(const struct nft_ctx *ctx,
 159                             const struct nft_expr *expr,
 160                             const struct nlattr * const tb[])
 161 {
 162         struct nft_bitwise *priv = nft_expr_priv(expr);
 163         u32 len;
 164         int err;
 165
 166         if (!tb[NFTA_BITWISE_SREG] ||
 167             !tb[NFTA_BITWISE_DREG] ||
 168             !tb[NFTA_BITWISE_LEN])
 169                 return -EINVAL;
 170
 171         err = nft_parse_u32_check(tb[NFTA_BITWISE_LEN], U8_MAX, &len);
 172         if (err < 0)
 173                 return err;
 174
 175         priv->len = len;
 176
 177         priv->sreg = nft_parse_register(tb[NFTA_BITWISE_SREG]);
 178         err = nft_validate_register_load(priv->sreg, priv->len);
 179         if (err < 0)
 180                 return err;
 181
 182         priv->dreg = nft_parse_register(tb[NFTA_BITWISE_DREG]);
 183         err = nft_validate_register_store(ctx, priv->dreg, NULL,
 184                                           NFT_DATA_VALUE, priv->len);
 185         if (err < 0)
 186                 return err;
 187
 188         if (tb[NFTA_BITWISE_OP]) {
 189                 priv->op = ntohl(nla_get_be32(tb[NFTA_BITWISE_OP]));
 190                 switch (priv->op) {
 191                 case NFT_BITWISE_BOOL:
 192                 case NFT_BITWISE_LSHIFT:
 193                 case NFT_BITWISE_RSHIFT:
 194                         break;
 195                 default:
 196                         return -EOPNOTSUPP;
 197                 }
 198         } else {
 199                 priv->op = NFT_BITWISE_BOOL;
 200         }
 201
 202         switch(priv->op) {
 203         case NFT_BITWISE_BOOL:
 204                 err = nft_bitwise_init_bool(priv, tb);
 205                 break;
 206         case NFT_BITWISE_LSHIFT:
 207         case NFT_BITWISE_RSHIFT:
 208                 err = nft_bitwise_init_shift(priv, tb);
 209                 break;
 210         }
 211
 212         return err;
 213 }
 214
 215 static int nft_bitwise_dump_bool(struct sk_buff *skb,
 216                                  const struct nft_bitwise *priv)
 217 {
 218         if (nft_data_dump(skb, NFTA_BITWISE_MASK, &priv->mask,
 219                           NFT_DATA_VALUE, priv->len) < 0)
 220                 return -1;
 221
 222         if (nft_data_dump(skb, NFTA_BITWISE_XOR, &priv->xor,
 223                           NFT_DATA_VALUE, priv->len) < 0)
 224                 return -1;
 225
 226         return 0;
 227 }
 228
 229 static int nft_bitwise_dump_shift(struct sk_buff *skb,
 230                                   const struct nft_bitwise *priv)
 231 {
 232         if (nft_data_dump(skb, NFTA_BITWISE_DATA, &priv->data,
 233                           NFT_DATA_VALUE, sizeof(u32)) < 0)
 234                 return -1;
 235         return 0;
 236 }
 237
 238 static int nft_bitwise_dump(struct sk_buff *skb, const struct nft_expr *expr)
 239 {
 240         const struct nft_bitwise *priv = nft_expr_priv(expr);
 241         int err = 0;
 242
 243         if (nft_dump_register(skb, NFTA_BITWISE_SREG, priv->sreg))
 244                 return -1;
 245         if (nft_dump_register(skb, NFTA_BITWISE_DREG, priv->dreg))
 246                 return -1;
 247         if (nla_put_be32(skb, NFTA_BITWISE_LEN, htonl(priv->len)))
 248                 return -1;
 249         if (nla_put_be32(skb, NFTA_BITWISE_OP, htonl(priv->op)))
 250                 return -1;
 251
 252         switch (priv->op) {
 253         case NFT_BITWISE_BOOL:
 254                 err = nft_bitwise_dump_bool(skb, priv);
 255                 break;
 256         case NFT_BITWISE_LSHIFT:
 257         case NFT_BITWISE_RSHIFT:
 258                 err = nft_bitwise_dump_shift(skb, priv);
 259                 break;
 260         }
 261
 262         return err;
 263 }
 264
 265 static struct nft_data zero;
 266
 267 static int nft_bitwise_offload(struct nft_offload_ctx *ctx,
 268                                struct nft_flow_rule *flow,
 269                                const struct nft_expr *expr)
 270 {
 271         const struct nft_bitwise *priv = nft_expr_priv(expr);
 272         struct nft_offload_reg *reg = &ctx->regs[priv->dreg];
 273
 274         if (priv->op != NFT_BITWISE_BOOL)
 275                 return -EOPNOTSUPP;
 276
 277         if (memcmp(&priv->xor, &zero, sizeof(priv->xor)) ||
 278             priv->sreg != priv->dreg || priv->len != reg->len)
 279                 return -EOPNOTSUPP;
 280
 281         memcpy(&reg->mask, &priv->mask, sizeof(priv->mask));
 282
 283         return 0;
 284 }
 285
 286 static const struct nft_expr_ops nft_bitwise_ops = {
 287         .type           = &nft_bitwise_type,
 288         .size           = NFT_EXPR_SIZE(sizeof(struct nft_bitwise)),
 289         .eval           = nft_bitwise_eval,
 290         .init           = nft_bitwise_init,
 291         .dump           = nft_bitwise_dump,
 292         .offload        = nft_bitwise_offload,
 293 };
 294
 295 struct nft_expr_type nft_bitwise_type __read_mostly = {
 296         .name           = "bitwise",
 297         .ops            = &nft_bitwise_ops,
 298         .policy         = nft_bitwise_policy,
 299         .maxattr        = NFTA_BITWISE_MAX,
 300         .owner          = THIS_MODULE,
 301 };