1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (c) 2016 Laura Garcia <nevola@gmail.com> 4 */ 5 6 #include <linux/kernel.h> 7 #include <linux/init.h> 8 #include <linux/module.h> 9 #include <linux/netlink.h> 10 #include <linux/netfilter.h> 11 #include <linux/netfilter/nf_tables.h> 12 #include <net/netfilter/nf_tables.h> 13 #include <net/netfilter/nf_tables_core.h> 14 #include <linux/jhash.h> 15 16 struct nft_jhash { 17 u8 sreg; 18 u8 dreg; 19 u8 len; 20 bool autogen_seed:1; 21 u32 modulus; 22 u32 seed; 23 u32 offset; 24 }; 25 26 static void nft_jhash_eval(const struct nft_expr *expr, 27 struct nft_regs *regs, 28 const struct nft_pktinfo *pkt) 29 { 30 struct nft_jhash *priv = nft_expr_priv(expr); 31 const void *data = ®s->data[priv->sreg]; 32 u32 h; 33 34 h = reciprocal_scale(jhash(data, priv->len, priv->seed), 35 priv->modulus); 36 37 regs->data[priv->dreg] = h + priv->offset; 38 } 39 40 struct nft_symhash { 41 u8 dreg; 42 u32 modulus; 43 u32 offset; 44 }; 45 46 static void nft_symhash_eval(const struct nft_expr *expr, 47 struct nft_regs *regs, 48 const struct nft_pktinfo *pkt) 49 { 50 struct nft_symhash *priv = nft_expr_priv(expr); 51 struct sk_buff *skb = pkt->skb; 52 u32 h; 53 54 h = reciprocal_scale(__skb_get_hash_symmetric(skb), priv->modulus); 55 56 regs->data[priv->dreg] = h + priv->offset; 57 } 58 59 static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = { 60 [NFTA_HASH_SREG] = { .type = NLA_U32 }, 61 [NFTA_HASH_DREG] = { .type = NLA_U32 }, 62 [NFTA_HASH_LEN] = NLA_POLICY_MAX(NLA_BE32, 255), 63 [NFTA_HASH_MODULUS] = { .type = NLA_U32 }, 64 [NFTA_HASH_SEED] = { .type = NLA_U32 }, 65 [NFTA_HASH_OFFSET] = { .type = NLA_U32 }, 66 [NFTA_HASH_TYPE] = { .type = NLA_U32 }, 67 }; 68 69 static int nft_jhash_init(const struct nft_ctx *ctx, 70 const struct nft_expr *expr, 71 const struct nlattr * const tb[]) 72 { 73 struct nft_jhash *priv = nft_expr_priv(expr); 74 u32 len; 75 int err; 76 77 if (!tb[NFTA_HASH_SREG] || 78 !tb[NFTA_HASH_DREG] || 79 !tb[NFTA_HASH_LEN] || 80 !tb[NFTA_HASH_MODULUS]) 81 return -EINVAL; 82 83 if (tb[NFTA_HASH_OFFSET]) 84 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET])); 85 86 err = nft_parse_u32_check(tb[NFTA_HASH_LEN], U8_MAX, &len); 87 if (err < 0) 88 return err; 89 if (len == 0) 90 return -ERANGE; 91 92 priv->len = len; 93 94 err = nft_parse_register_load(tb[NFTA_HASH_SREG], &priv->sreg, len); 95 if (err < 0) 96 return err; 97 98 priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS])); 99 if (priv->modulus < 1) 100 return -ERANGE; 101 102 if (priv->offset + priv->modulus - 1 < priv->offset) 103 return -EOVERFLOW; 104 105 if (tb[NFTA_HASH_SEED]) { 106 priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED])); 107 } else { 108 priv->autogen_seed = true; 109 get_random_bytes(&priv->seed, sizeof(priv->seed)); 110 } 111 112 return nft_parse_register_store(ctx, tb[NFTA_HASH_DREG], &priv->dreg, 113 NULL, NFT_DATA_VALUE, sizeof(u32)); 114 } 115 116 static int nft_symhash_init(const struct nft_ctx *ctx, 117 const struct nft_expr *expr, 118 const struct nlattr * const tb[]) 119 { 120 struct nft_symhash *priv = nft_expr_priv(expr); 121 122 if (!tb[NFTA_HASH_DREG] || 123 !tb[NFTA_HASH_MODULUS]) 124 return -EINVAL; 125 126 if (tb[NFTA_HASH_OFFSET]) 127 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET])); 128 129 priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS])); 130 if (priv->modulus < 1) 131 return -ERANGE; 132 133 if (priv->offset + priv->modulus - 1 < priv->offset) 134 return -EOVERFLOW; 135 136 return nft_parse_register_store(ctx, tb[NFTA_HASH_DREG], 137 &priv->dreg, NULL, NFT_DATA_VALUE, 138 sizeof(u32)); 139 } 140 141 static int nft_jhash_dump(struct sk_buff *skb, 142 const struct nft_expr *expr, bool reset) 143 { 144 const struct nft_jhash *priv = nft_expr_priv(expr); 145 146 if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg)) 147 goto nla_put_failure; 148 if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg)) 149 goto nla_put_failure; 150 if (nla_put_be32(skb, NFTA_HASH_LEN, htonl(priv->len))) 151 goto nla_put_failure; 152 if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus))) 153 goto nla_put_failure; 154 if (!priv->autogen_seed && 155 nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed))) 156 goto nla_put_failure; 157 if (priv->offset != 0) 158 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset))) 159 goto nla_put_failure; 160 if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_JENKINS))) 161 goto nla_put_failure; 162 return 0; 163 164 nla_put_failure: 165 return -1; 166 } 167 168 static bool nft_jhash_reduce(struct nft_regs_track *track, 169 const struct nft_expr *expr) 170 { 171 const struct nft_jhash *priv = nft_expr_priv(expr); 172 173 nft_reg_track_cancel(track, priv->dreg, sizeof(u32)); 174 175 return false; 176 } 177 178 static int nft_symhash_dump(struct sk_buff *skb, 179 const struct nft_expr *expr, bool reset) 180 { 181 const struct nft_symhash *priv = nft_expr_priv(expr); 182 183 if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg)) 184 goto nla_put_failure; 185 if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus))) 186 goto nla_put_failure; 187 if (priv->offset != 0) 188 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset))) 189 goto nla_put_failure; 190 if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_SYM))) 191 goto nla_put_failure; 192 return 0; 193 194 nla_put_failure: 195 return -1; 196 } 197 198 static bool nft_symhash_reduce(struct nft_regs_track *track, 199 const struct nft_expr *expr) 200 { 201 struct nft_symhash *priv = nft_expr_priv(expr); 202 struct nft_symhash *symhash; 203 204 if (!nft_reg_track_cmp(track, expr, priv->dreg)) { 205 nft_reg_track_update(track, expr, priv->dreg, sizeof(u32)); 206 return false; 207 } 208 209 symhash = nft_expr_priv(track->regs[priv->dreg].selector); 210 if (priv->offset != symhash->offset || 211 priv->modulus != symhash->modulus) { 212 nft_reg_track_update(track, expr, priv->dreg, sizeof(u32)); 213 return false; 214 } 215 216 if (!track->regs[priv->dreg].bitwise) 217 return true; 218 219 return false; 220 } 221 222 static struct nft_expr_type nft_hash_type; 223 static const struct nft_expr_ops nft_jhash_ops = { 224 .type = &nft_hash_type, 225 .size = NFT_EXPR_SIZE(sizeof(struct nft_jhash)), 226 .eval = nft_jhash_eval, 227 .init = nft_jhash_init, 228 .dump = nft_jhash_dump, 229 .reduce = nft_jhash_reduce, 230 }; 231 232 static const struct nft_expr_ops nft_symhash_ops = { 233 .type = &nft_hash_type, 234 .size = NFT_EXPR_SIZE(sizeof(struct nft_symhash)), 235 .eval = nft_symhash_eval, 236 .init = nft_symhash_init, 237 .dump = nft_symhash_dump, 238 .reduce = nft_symhash_reduce, 239 }; 240 241 static const struct nft_expr_ops * 242 nft_hash_select_ops(const struct nft_ctx *ctx, 243 const struct nlattr * const tb[]) 244 { 245 u32 type; 246 247 if (!tb[NFTA_HASH_TYPE]) 248 return &nft_jhash_ops; 249 250 type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE])); 251 switch (type) { 252 case NFT_HASH_SYM: 253 return &nft_symhash_ops; 254 case NFT_HASH_JENKINS: 255 return &nft_jhash_ops; 256 default: 257 break; 258 } 259 return ERR_PTR(-EOPNOTSUPP); 260 } 261 262 static struct nft_expr_type nft_hash_type __read_mostly = { 263 .name = "hash", 264 .select_ops = nft_hash_select_ops, 265 .policy = nft_hash_policy, 266 .maxattr = NFTA_HASH_MAX, 267 .owner = THIS_MODULE, 268 }; 269 270 static int __init nft_hash_module_init(void) 271 { 272 return nft_register_expr(&nft_hash_type); 273 } 274 275 static void __exit nft_hash_module_exit(void) 276 { 277 nft_unregister_expr(&nft_hash_type); 278 } 279 280 module_init(nft_hash_module_init); 281 module_exit(nft_hash_module_exit); 282 283 MODULE_LICENSE("GPL"); 284 MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>"); 285 MODULE_ALIAS_NFT_EXPR("hash"); 286 MODULE_DESCRIPTION("Netfilter nftables hash module"); 287