cregit-Linux how code gets into the kernel

Release 4.11 net/ipv6/netfilter/nf_socket_ipv6.c

/*
 * Copyright (C) 2007-2008 BalaBit IT Ltd.
 * Author: Krisztian Kovacs
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/icmp.h>
#include <net/sock.h>
#include <net/inet_sock.h>
#include <net/inet6_hashtables.h>
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
#include <net/netfilter/nf_socket.h>
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#include <net/netfilter/nf_conntrack.h>
#endif


static int extract_icmp6_fields(const struct sk_buff *skb, unsigned int outside_hdrlen, int *protocol, const struct in6_addr **raddr, const struct in6_addr **laddr, __be16 *rport, __be16 *lport, struct ipv6hdr *ipv6_var) { const struct ipv6hdr *inside_iph; struct icmp6hdr *icmph, _icmph; __be16 *ports, _ports[2]; u8 inside_nexthdr; __be16 inside_fragoff; int inside_hdrlen; icmph = skb_header_pointer(skb, outside_hdrlen, sizeof(_icmph), &_icmph); if (icmph == NULL) return 1; if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK) return 1; inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph), sizeof(*ipv6_var), ipv6_var); if (inside_iph == NULL) return 1; inside_nexthdr = inside_iph->nexthdr; inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) + sizeof(*ipv6_var), &inside_nexthdr, &inside_fragoff); if (inside_hdrlen < 0) return 1; /* hjm: Packet has no/incomplete transport layer headers. */ if (inside_nexthdr != IPPROTO_TCP && inside_nexthdr != IPPROTO_UDP) return 1; ports = skb_header_pointer(skb, inside_hdrlen, sizeof(_ports), &_ports); if (ports == NULL) return 1; /* the inside IP packet is the one quoted from our side, thus * its saddr is the local address */ *protocol = inside_nexthdr; *laddr = &inside_iph->saddr; *lport = ports[0]; *raddr = &inside_iph->daddr; *rport = ports[1]; return 0; }

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static struct sock * nf_socket_get_sock_v6(struct net *net, struct sk_buff *skb, int doff, const u8 protocol, const struct in6_addr *saddr, const struct in6_addr *daddr, const __be16 sport, const __be16 dport, const struct net_device *in) { switch (protocol) { case IPPROTO_TCP: return inet6_lookup(net, &tcp_hashinfo, skb, doff, saddr, sport, daddr, dport, in->ifindex); case IPPROTO_UDP: return udp6_lib_lookup(net, saddr, sport, daddr, dport, in->ifindex); } return NULL; }

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struct sock *nf_sk_lookup_slow_v6(struct net *net, const struct sk_buff *skb, const struct net_device *indev) { __be16 uninitialized_var(dport), uninitialized_var(sport); const struct in6_addr *daddr = NULL, *saddr = NULL; struct ipv6hdr *iph = ipv6_hdr(skb); struct sk_buff *data_skb = NULL; int doff = 0; int thoff = 0, tproto; tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL); if (tproto < 0) { pr_debug("unable to find transport header in IPv6 packet, dropping\n"); return NULL; } if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) { struct udphdr _hdr, *hp; hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr); if (hp == NULL) return NULL; saddr = &iph->saddr; sport = hp->source; daddr = &iph->daddr; dport = hp->dest; data_skb = (struct sk_buff *)skb; doff = tproto == IPPROTO_TCP ? thoff + __tcp_hdrlen((struct tcphdr *)hp) : thoff + sizeof(*hp); } else if (tproto == IPPROTO_ICMPV6) { struct ipv6hdr ipv6_var; if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr, &sport, &dport, &ipv6_var)) return NULL; } else { return NULL; } return nf_socket_get_sock_v6(net, data_skb, doff, tproto, saddr, daddr, sport, dport, indev); }

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EXPORT_SYMBOL_GPL(nf_sk_lookup_slow_v6); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler"); MODULE_DESCRIPTION("Netfilter IPv6 socket lookup infrastructure");

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