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 <linux/static_key.h> 13 #include <net/netfilter/nf_tables.h> 14 #include <net/netfilter/nf_tables_core.h> 15 16 static DEFINE_PER_CPU(struct rnd_state, nft_numgen_prandom_state); 17 18 struct nft_ng_inc { 19 u8 dreg; 20 u32 modulus; 21 atomic_t *counter; 22 u32 offset; 23 }; 24 25 static u32 nft_ng_inc_gen(struct nft_ng_inc *priv) 26 { 27 u32 nval, oval; 28 29 do { 30 oval = atomic_read(priv->counter); 31 nval = (oval + 1 < priv->modulus) ? oval + 1 : 0; 32 } while (atomic_cmpxchg(priv->counter, oval, nval) != oval); 33 34 return nval + priv->offset; 35 } 36 37 static void nft_ng_inc_eval(const struct nft_expr *expr, 38 struct nft_regs *regs, 39 const struct nft_pktinfo *pkt) 40 { 41 struct nft_ng_inc *priv = nft_expr_priv(expr); 42 43 regs->data[priv->dreg] = nft_ng_inc_gen(priv); 44 } 45 46 static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = { 47 [NFTA_NG_DREG] = { .type = NLA_U32 }, 48 [NFTA_NG_MODULUS] = { .type = NLA_U32 }, 49 [NFTA_NG_TYPE] = { .type = NLA_U32 }, 50 [NFTA_NG_OFFSET] = { .type = NLA_U32 }, 51 }; 52 53 static int nft_ng_inc_init(const struct nft_ctx *ctx, 54 const struct nft_expr *expr, 55 const struct nlattr * const tb[]) 56 { 57 struct nft_ng_inc *priv = nft_expr_priv(expr); 58 int err; 59 60 if (tb[NFTA_NG_OFFSET]) 61 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET])); 62 63 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS])); 64 if (priv->modulus == 0) 65 return -ERANGE; 66 67 if (priv->offset + priv->modulus - 1 < priv->offset) 68 return -EOVERFLOW; 69 70 priv->counter = kmalloc(sizeof(*priv->counter), GFP_KERNEL); 71 if (!priv->counter) 72 return -ENOMEM; 73 74 atomic_set(priv->counter, priv->modulus - 1); 75 76 err = nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg, 77 NULL, NFT_DATA_VALUE, sizeof(u32)); 78 if (err < 0) 79 goto err; 80 81 return 0; 82 err: 83 kfree(priv->counter); 84 85 return err; 86 } 87 88 static bool nft_ng_inc_reduce(struct nft_regs_track *track, 89 const struct nft_expr *expr) 90 { 91 const struct nft_ng_inc *priv = nft_expr_priv(expr); 92 93 nft_reg_track_cancel(track, priv->dreg, NFT_REG32_SIZE); 94 95 return false; 96 } 97 98 static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg, 99 u32 modulus, enum nft_ng_types type, u32 offset) 100 { 101 if (nft_dump_register(skb, NFTA_NG_DREG, dreg)) 102 goto nla_put_failure; 103 if (nla_put_be32(skb, NFTA_NG_MODULUS, htonl(modulus))) 104 goto nla_put_failure; 105 if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type))) 106 goto nla_put_failure; 107 if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset))) 108 goto nla_put_failure; 109 110 return 0; 111 112 nla_put_failure: 113 return -1; 114 } 115 116 static int nft_ng_inc_dump(struct sk_buff *skb, const struct nft_expr *expr) 117 { 118 const struct nft_ng_inc *priv = nft_expr_priv(expr); 119 120 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL, 121 priv->offset); 122 } 123 124 static void nft_ng_inc_destroy(const struct nft_ctx *ctx, 125 const struct nft_expr *expr) 126 { 127 const struct nft_ng_inc *priv = nft_expr_priv(expr); 128 129 kfree(priv->counter); 130 } 131 132 struct nft_ng_random { 133 u8 dreg; 134 u32 modulus; 135 u32 offset; 136 }; 137 138 static u32 nft_ng_random_gen(struct nft_ng_random *priv) 139 { 140 struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state); 141 142 return reciprocal_scale(prandom_u32_state(state), priv->modulus) + 143 priv->offset; 144 } 145 146 static void nft_ng_random_eval(const struct nft_expr *expr, 147 struct nft_regs *regs, 148 const struct nft_pktinfo *pkt) 149 { 150 struct nft_ng_random *priv = nft_expr_priv(expr); 151 152 regs->data[priv->dreg] = nft_ng_random_gen(priv); 153 } 154 155 static int nft_ng_random_init(const struct nft_ctx *ctx, 156 const struct nft_expr *expr, 157 const struct nlattr * const tb[]) 158 { 159 struct nft_ng_random *priv = nft_expr_priv(expr); 160 161 if (tb[NFTA_NG_OFFSET]) 162 priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET])); 163 164 priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS])); 165 if (priv->modulus == 0) 166 return -ERANGE; 167 168 if (priv->offset + priv->modulus - 1 < priv->offset) 169 return -EOVERFLOW; 170 171 prandom_init_once(&nft_numgen_prandom_state); 172 173 return nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg, 174 NULL, NFT_DATA_VALUE, sizeof(u32)); 175 } 176 177 static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr) 178 { 179 const struct nft_ng_random *priv = nft_expr_priv(expr); 180 181 return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM, 182 priv->offset); 183 } 184 185 static bool nft_ng_random_reduce(struct nft_regs_track *track, 186 const struct nft_expr *expr) 187 { 188 const struct nft_ng_random *priv = nft_expr_priv(expr); 189 190 nft_reg_track_cancel(track, priv->dreg, NFT_REG32_SIZE); 191 192 return false; 193 } 194 195 static struct nft_expr_type nft_ng_type; 196 static const struct nft_expr_ops nft_ng_inc_ops = { 197 .type = &nft_ng_type, 198 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_inc)), 199 .eval = nft_ng_inc_eval, 200 .init = nft_ng_inc_init, 201 .destroy = nft_ng_inc_destroy, 202 .dump = nft_ng_inc_dump, 203 .reduce = nft_ng_inc_reduce, 204 }; 205 206 static const struct nft_expr_ops nft_ng_random_ops = { 207 .type = &nft_ng_type, 208 .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_random)), 209 .eval = nft_ng_random_eval, 210 .init = nft_ng_random_init, 211 .dump = nft_ng_random_dump, 212 .reduce = nft_ng_random_reduce, 213 }; 214 215 static const struct nft_expr_ops * 216 nft_ng_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[]) 217 { 218 u32 type; 219 220 if (!tb[NFTA_NG_DREG] || 221 !tb[NFTA_NG_MODULUS] || 222 !tb[NFTA_NG_TYPE]) 223 return ERR_PTR(-EINVAL); 224 225 type = ntohl(nla_get_be32(tb[NFTA_NG_TYPE])); 226 227 switch (type) { 228 case NFT_NG_INCREMENTAL: 229 return &nft_ng_inc_ops; 230 case NFT_NG_RANDOM: 231 return &nft_ng_random_ops; 232 } 233 234 return ERR_PTR(-EINVAL); 235 } 236 237 static struct nft_expr_type nft_ng_type __read_mostly = { 238 .name = "numgen", 239 .select_ops = nft_ng_select_ops, 240 .policy = nft_ng_policy, 241 .maxattr = NFTA_NG_MAX, 242 .owner = THIS_MODULE, 243 }; 244 245 static int __init nft_ng_module_init(void) 246 { 247 return nft_register_expr(&nft_ng_type); 248 } 249 250 static void __exit nft_ng_module_exit(void) 251 { 252 nft_unregister_expr(&nft_ng_type); 253 } 254 255 module_init(nft_ng_module_init); 256 module_exit(nft_ng_module_exit); 257 258 MODULE_LICENSE("GPL"); 259 MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>"); 260 MODULE_ALIAS_NFT_EXPR("numgen"); 261 MODULE_DESCRIPTION("nftables number generator module"); 262