diff options
Diffstat (limited to 'net/ipv4/netfilter/nf_tproxy_ipv4.c')
| -rw-r--r-- | net/ipv4/netfilter/nf_tproxy_ipv4.c | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/nf_tproxy_ipv4.c b/net/ipv4/netfilter/nf_tproxy_ipv4.c new file mode 100644 index 000000000..69e331799 --- /dev/null +++ b/net/ipv4/netfilter/nf_tproxy_ipv4.c @@ -0,0 +1,152 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2007-2008 BalaBit IT Ltd. + * Author: Krisztian Kovacs + */ + +#include <net/netfilter/nf_tproxy.h> +#include <linux/module.h> +#include <linux/skbuff.h> +#include <net/sock.h> +#include <net/inet_sock.h> +#include <linux/ip.h> +#include <net/checksum.h> +#include <net/udp.h> +#include <net/tcp.h> +#include <linux/inetdevice.h> + +struct sock * +nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb, + __be32 laddr, __be16 lport, struct sock *sk) +{ + const struct iphdr *iph = ip_hdr(skb); + struct tcphdr _hdr, *hp; + + hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); + if (hp == NULL) { + inet_twsk_put(inet_twsk(sk)); + return NULL; + } + + if (hp->syn && !hp->rst && !hp->ack && !hp->fin) { + /* SYN to a TIME_WAIT socket, we'd rather redirect it + * to a listener socket if there's one */ + struct sock *sk2; + + sk2 = nf_tproxy_get_sock_v4(net, skb, iph->protocol, + iph->saddr, laddr ? laddr : iph->daddr, + hp->source, lport ? lport : hp->dest, + skb->dev, NF_TPROXY_LOOKUP_LISTENER); + if (sk2) { + nf_tproxy_twsk_deschedule_put(inet_twsk(sk)); + sk = sk2; + } + } + + return sk; +} +EXPORT_SYMBOL_GPL(nf_tproxy_handle_time_wait4); + +__be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr) +{ + const struct in_ifaddr *ifa; + struct in_device *indev; + __be32 laddr; + + if (user_laddr) + return user_laddr; + + laddr = 0; + indev = __in_dev_get_rcu(skb->dev); + + in_dev_for_each_ifa_rcu(ifa, indev) { + if (ifa->ifa_flags & IFA_F_SECONDARY) + continue; + + laddr = ifa->ifa_local; + break; + } + + return laddr ? laddr : daddr; +} +EXPORT_SYMBOL_GPL(nf_tproxy_laddr4); + +struct sock * +nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, + const u8 protocol, + const __be32 saddr, const __be32 daddr, + const __be16 sport, const __be16 dport, + const struct net_device *in, + const enum nf_tproxy_lookup_t lookup_type) +{ + struct inet_hashinfo *hinfo = net->ipv4.tcp_death_row.hashinfo; + struct sock *sk; + + switch (protocol) { + case IPPROTO_TCP: { + struct tcphdr _hdr, *hp; + + hp = skb_header_pointer(skb, ip_hdrlen(skb), + sizeof(struct tcphdr), &_hdr); + if (hp == NULL) + return NULL; + + switch (lookup_type) { + case NF_TPROXY_LOOKUP_LISTENER: + sk = inet_lookup_listener(net, hinfo, skb, + ip_hdrlen(skb) + __tcp_hdrlen(hp), + saddr, sport, daddr, dport, + in->ifindex, 0); + + if (sk && !refcount_inc_not_zero(&sk->sk_refcnt)) + sk = NULL; + /* NOTE: we return listeners even if bound to + * 0.0.0.0, those are filtered out in + * xt_socket, since xt_TPROXY needs 0 bound + * listeners too + */ + break; + case NF_TPROXY_LOOKUP_ESTABLISHED: + sk = inet_lookup_established(net, hinfo, saddr, sport, + daddr, dport, in->ifindex); + break; + default: + BUG(); + } + break; + } + case IPPROTO_UDP: + sk = udp4_lib_lookup(net, saddr, sport, daddr, dport, + in->ifindex); + if (sk) { + int connected = (sk->sk_state == TCP_ESTABLISHED); + int wildcard = (inet_sk(sk)->inet_rcv_saddr == 0); + + /* NOTE: we return listeners even if bound to + * 0.0.0.0, those are filtered out in + * xt_socket, since xt_TPROXY needs 0 bound + * listeners too + */ + if ((lookup_type == NF_TPROXY_LOOKUP_ESTABLISHED && + (!connected || wildcard)) || + (lookup_type == NF_TPROXY_LOOKUP_LISTENER && connected)) { + sock_put(sk); + sk = NULL; + } + } + break; + default: + WARN_ON(1); + sk = NULL; + } + + pr_debug("tproxy socket lookup: proto %u %08x:%u -> %08x:%u, lookup type: %d, sock %p\n", + protocol, ntohl(saddr), ntohs(sport), ntohl(daddr), ntohs(dport), lookup_type, sk); + + return sk; +} +EXPORT_SYMBOL_GPL(nf_tproxy_get_sock_v4); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs"); +MODULE_DESCRIPTION("Netfilter IPv4 transparent proxy support"); |