From 3ff7ddb1353da9b535e65702704cbadea1da9a00 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Fri, 24 Apr 2020 21:55:37 +0200 Subject: [PATCH] netfilter: nft_nat: add netmap support This patch allows you to NAT the network address prefix onto another network address prefix, a.k.a. netmapping. Userspace must specify the NF_NAT_RANGE_NETMAP flag and the prefix address through the NFTA_NAT_REG_ADDR_MIN and NFTA_NAT_REG_ADDR_MAX netlink attributes. Signed-off-by: Pablo Neira Ayuso --- include/uapi/linux/netfilter/nf_nat.h | 4 ++- net/netfilter/nft_nat.c | 46 ++++++++++++++++++++++++++- 2 files changed, 48 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/netfilter/nf_nat.h b/include/uapi/linux/netfilter/nf_nat.h index 4a95c0db14d4..a64586e77b24 100644 --- a/include/uapi/linux/netfilter/nf_nat.h +++ b/include/uapi/linux/netfilter/nf_nat.h @@ -11,6 +11,7 @@ #define NF_NAT_RANGE_PERSISTENT (1 << 3) #define NF_NAT_RANGE_PROTO_RANDOM_FULLY (1 << 4) #define NF_NAT_RANGE_PROTO_OFFSET (1 << 5) +#define NF_NAT_RANGE_NETMAP (1 << 6) #define NF_NAT_RANGE_PROTO_RANDOM_ALL \ (NF_NAT_RANGE_PROTO_RANDOM | NF_NAT_RANGE_PROTO_RANDOM_FULLY) @@ -18,7 +19,8 @@ #define NF_NAT_RANGE_MASK \ (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED | \ NF_NAT_RANGE_PROTO_RANDOM | NF_NAT_RANGE_PERSISTENT | \ - NF_NAT_RANGE_PROTO_RANDOM_FULLY | NF_NAT_RANGE_PROTO_OFFSET) + NF_NAT_RANGE_PROTO_RANDOM_FULLY | NF_NAT_RANGE_PROTO_OFFSET | \ + NF_NAT_RANGE_NETMAP) struct nf_nat_ipv4_range { unsigned int flags; diff --git a/net/netfilter/nft_nat.c b/net/netfilter/nft_nat.c index 7442aa8b1555..23a7bfd10521 100644 --- a/net/netfilter/nft_nat.c +++ b/net/netfilter/nft_nat.c @@ -60,6 +60,46 @@ static void nft_nat_setup_proto(struct nf_nat_range2 *range, nft_reg_load16(®s->data[priv->sreg_proto_max]); } +static void nft_nat_setup_netmap(struct nf_nat_range2 *range, + const struct nft_pktinfo *pkt, + const struct nft_nat *priv) +{ + struct sk_buff *skb = pkt->skb; + union nf_inet_addr new_addr; + __be32 netmask; + int i, len = 0; + + switch (priv->type) { + case NFT_NAT_SNAT: + if (nft_pf(pkt) == NFPROTO_IPV4) { + new_addr.ip = ip_hdr(skb)->saddr; + len = sizeof(struct in_addr); + } else { + new_addr.in6 = ipv6_hdr(skb)->saddr; + len = sizeof(struct in6_addr); + } + break; + case NFT_NAT_DNAT: + if (nft_pf(pkt) == NFPROTO_IPV4) { + new_addr.ip = ip_hdr(skb)->daddr; + len = sizeof(struct in_addr); + } else { + new_addr.in6 = ipv6_hdr(skb)->daddr; + len = sizeof(struct in6_addr); + } + break; + } + + for (i = 0; i < len / sizeof(__be32); i++) { + netmask = ~(range->min_addr.ip6[i] ^ range->max_addr.ip6[i]); + new_addr.ip6[i] &= ~netmask; + new_addr.ip6[i] |= range->min_addr.ip6[i] & netmask; + } + + range->min_addr = new_addr; + range->max_addr = new_addr; +} + static void nft_nat_eval(const struct nft_expr *expr, struct nft_regs *regs, const struct nft_pktinfo *pkt) @@ -70,8 +110,12 @@ static void nft_nat_eval(const struct nft_expr *expr, struct nf_nat_range2 range; memset(&range, 0, sizeof(range)); - if (priv->sreg_addr_min) + + if (priv->sreg_addr_min) { nft_nat_setup_addr(&range, regs, priv); + if (priv->flags & NF_NAT_RANGE_NETMAP) + nft_nat_setup_netmap(&range, pkt, priv); + } if (priv->sreg_proto_min) nft_nat_setup_proto(&range, regs, priv); -- 2.30.2