From 2b03bf732488a3c2e920afe22c03b82cb8477e28 Mon Sep 17 00:00:00 2001 From: Laura Garcia Liebana Date: Tue, 13 Sep 2016 13:49:53 +0200 Subject: [PATCH] netfilter: nft_numgen: add number generation offset Add support of an offset value for incremental counter and random. With this option the sysadmin is able to start the counter to a certain value and then apply the generated number. Example: meta mark set numgen inc mod 2 offset 100 This will generate marks with the serie 100, 101, 100, 101, ... Suggested-by: Pablo Neira Ayuso Signed-off-by: Laura Garcia Liebana Signed-off-by: Pablo Neira Ayuso --- include/uapi/linux/netfilter/nf_tables.h | 2 ++ net/netfilter/nft_numgen.c | 32 +++++++++++++++++++----- 2 files changed, 28 insertions(+), 6 deletions(-) diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h index bc0eb6a1066d..bcfb892ff148 100644 --- a/include/uapi/linux/netfilter/nf_tables.h +++ b/include/uapi/linux/netfilter/nf_tables.h @@ -1136,12 +1136,14 @@ enum nft_trace_types { * @NFTA_NG_DREG: destination register (NLA_U32) * @NFTA_NG_MODULUS: maximum counter value (NLA_U32) * @NFTA_NG_TYPE: operation type (NLA_U32) + * @NFTA_NG_OFFSET: offset to be added to the counter (NLA_U32) */ enum nft_ng_attributes { NFTA_NG_UNSPEC, NFTA_NG_DREG, NFTA_NG_MODULUS, NFTA_NG_TYPE, + NFTA_NG_OFFSET, __NFTA_NG_MAX }; #define NFTA_NG_MAX (__NFTA_NG_MAX - 1) diff --git a/net/netfilter/nft_numgen.c b/net/netfilter/nft_numgen.c index f173ebec30a7..55bc5ab78d4a 100644 --- a/net/netfilter/nft_numgen.c +++ b/net/netfilter/nft_numgen.c @@ -23,6 +23,7 @@ struct nft_ng_inc { enum nft_registers dreg:8; u32 modulus; atomic_t counter; + u32 offset; }; static void nft_ng_inc_eval(const struct nft_expr *expr, @@ -37,13 +38,14 @@ static void nft_ng_inc_eval(const struct nft_expr *expr, nval = (oval + 1 < priv->modulus) ? oval + 1 : 0; } while (atomic_cmpxchg(&priv->counter, oval, nval) != oval); - regs->data[priv->dreg] = nval; + regs->data[priv->dreg] = nval + priv->offset; } static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = { [NFTA_NG_DREG] = { .type = NLA_U32 }, [NFTA_NG_MODULUS] = { .type = NLA_U32 }, [NFTA_NG_TYPE] = { .type = NLA_U32 }, + [NFTA_NG_OFFSET] = { .type = NLA_U32 }, }; static int nft_ng_inc_init(const struct nft_ctx *ctx, @@ -52,10 +54,16 @@ static int nft_ng_inc_init(const struct nft_ctx *ctx, { struct nft_ng_inc *priv = nft_expr_priv(expr); + if (tb[NFTA_NG_OFFSET]) + priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET])); + priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS])); if (priv->modulus == 0) return -ERANGE; + if (priv->offset + priv->modulus - 1 < priv->offset) + return -EOVERFLOW; + priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]); atomic_set(&priv->counter, 0); @@ -64,7 +72,7 @@ static int nft_ng_inc_init(const struct nft_ctx *ctx, } static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg, - u32 modulus, enum nft_ng_types type) + u32 modulus, enum nft_ng_types type, u32 offset) { if (nft_dump_register(skb, NFTA_NG_DREG, dreg)) goto nla_put_failure; @@ -72,6 +80,8 @@ static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg, goto nla_put_failure; if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type))) goto nla_put_failure; + if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset))) + goto nla_put_failure; return 0; @@ -83,12 +93,14 @@ static int nft_ng_inc_dump(struct sk_buff *skb, const struct nft_expr *expr) { const struct nft_ng_inc *priv = nft_expr_priv(expr); - return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL); + return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL, + priv->offset); } struct nft_ng_random { enum nft_registers dreg:8; u32 modulus; + u32 offset; }; static void nft_ng_random_eval(const struct nft_expr *expr, @@ -97,9 +109,10 @@ static void nft_ng_random_eval(const struct nft_expr *expr, { struct nft_ng_random *priv = nft_expr_priv(expr); struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state); + u32 val; - regs->data[priv->dreg] = reciprocal_scale(prandom_u32_state(state), - priv->modulus); + val = reciprocal_scale(prandom_u32_state(state), priv->modulus); + regs->data[priv->dreg] = val + priv->offset; } static int nft_ng_random_init(const struct nft_ctx *ctx, @@ -108,10 +121,16 @@ static int nft_ng_random_init(const struct nft_ctx *ctx, { struct nft_ng_random *priv = nft_expr_priv(expr); + if (tb[NFTA_NG_OFFSET]) + priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET])); + priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS])); if (priv->modulus == 0) return -ERANGE; + if (priv->offset + priv->modulus - 1 < priv->offset) + return -EOVERFLOW; + prandom_init_once(&nft_numgen_prandom_state); priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]); @@ -124,7 +143,8 @@ static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr) { const struct nft_ng_random *priv = nft_expr_priv(expr); - return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM); + return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM, + priv->offset); } static struct nft_expr_type nft_ng_type; -- 2.20.1