cregit-Linux how code gets into the kernel

Release 4.11 net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
 *
 * 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.
 */

#include <linux/types.h>
#include <linux/ip.h>
#include <linux/netfilter.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/icmp.h>
#include <linux/sysctl.h>
#include <net/route.h>
#include <net/ip.h>

#include <linux/netfilter_ipv4.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_l3proto.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_seqadj.h>
#include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
#include <net/netfilter/nf_log.h>


static int conntrack4_net_id __read_mostly;
static DEFINE_MUTEX(register_ipv4_hooks);


struct conntrack4_net {
	
unsigned int users;
};


static bool ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff, struct nf_conntrack_tuple *tuple) { const __be32 *ap; __be32 _addrs[2]; ap = skb_header_pointer(skb, nhoff + offsetof(struct iphdr, saddr), sizeof(u_int32_t) * 2, _addrs); if (ap == NULL) return false; tuple->src.u3.ip = ap[0]; tuple->dst.u3.ip = ap[1]; return true; }

Contributors

PersonTokensPropCommitsCommitProp
Yasuyuki Kozakai8790.62%125.00%
Jan Engelhardt88.33%250.00%
Patrick McHardy11.04%125.00%
Total96100.00%4100.00%


static bool ipv4_invert_tuple(struct nf_conntrack_tuple *tuple, const struct nf_conntrack_tuple *orig) { tuple->src.u3.ip = orig->dst.u3.ip; tuple->dst.u3.ip = orig->src.u3.ip; return true; }

Contributors

PersonTokensPropCommitsCommitProp
Yasuyuki Kozakai5096.15%150.00%
Jan Engelhardt23.85%150.00%
Total52100.00%2100.00%


static void ipv4_print_tuple(struct seq_file *s, const struct nf_conntrack_tuple *tuple) { seq_printf(s, "src=%pI4 dst=%pI4 ", &tuple->src.u3.ip, &tuple->dst.u3.ip); }

Contributors

PersonTokensPropCommitsCommitProp
Yasuyuki Kozakai3788.10%133.33%
Harvey Harrison37.14%133.33%
Joe Perches24.76%133.33%
Total42100.00%3100.00%


static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff, unsigned int *dataoff, u_int8_t *protonum) { const struct iphdr *iph; struct iphdr _iph; iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph); if (iph == NULL) return -NF_ACCEPT; /* Conntrack defragments packets, we might still see fragments * inside ICMP packets though. */ if (iph->frag_off & htons(IP_OFFSET)) return -NF_ACCEPT; *dataoff = nhoff + (iph->ihl << 2); *protonum = iph->protocol; /* Check bogus IP headers */ if (*dataoff > skb->len) { pr_debug("nf_conntrack_ipv4: bogus IPv4 packet: " "nhoff %u, ihl %u, skblen %u\n", nhoff, iph->ihl << 2, skb->len); return -NF_ACCEPT; } return NF_ACCEPT; }

Contributors

PersonTokensPropCommitsCommitProp
Yasuyuki Kozakai9368.89%233.33%
Jozsef Kadlecsik3626.67%233.33%
Jan Engelhardt53.70%116.67%
Patrick McHardy10.74%116.67%
Total135100.00%6100.00%


static unsigned int ipv4_helper(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { struct nf_conn *ct; enum ip_conntrack_info ctinfo; const struct nf_conn_help *help; const struct nf_conntrack_helper *helper; /* This is where we call the helper: as the packet goes out. */ ct = nf_ct_get(skb, &ctinfo); if (!ct || ctinfo == IP_CT_RELATED_REPLY) return NF_ACCEPT; help = nfct_help(ct); if (!help) return NF_ACCEPT; /* rcu_read_lock()ed by nf_hook_thresh */ helper = rcu_dereference(help->helper); if (!helper) return NF_ACCEPT; return helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb), ct, ctinfo); }

Contributors

PersonTokensPropCommitsCommitProp
Yasuyuki Kozakai5142.15%15.88%
Patrick McHardy2218.18%529.41%
Harald Welte1814.88%15.88%
Pablo Neira Ayuso119.09%211.76%
Arnaldo Carvalho de Melo64.96%211.76%
Herbert Xu54.13%15.88%
Eric W. Biedermann21.65%15.88%
David S. Miller21.65%15.88%
Jan Engelhardt21.65%15.88%
Eric Dumazet10.83%15.88%
Aaron Conole10.83%15.88%
Total121100.00%17100.00%


static unsigned int ipv4_confirm(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { struct nf_conn *ct; enum ip_conntrack_info ctinfo; ct = nf_ct_get(skb, &ctinfo); if (!ct || ctinfo == IP_CT_RELATED_REPLY) goto out; /* adjust seqs for loopback traffic only in outgoing direction */ if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) && !nf_is_loopback_packet(skb)) { if (!nf_ct_seq_adjust(skb, ct, ctinfo, ip_hdrlen(skb))) { NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop); return NF_DROP; } } out: /* We've seen it coming out the other side: confirm it */ return nf_conntrack_confirm(skb); }

Contributors

PersonTokensPropCommitsCommitProp
Pablo Neira Ayuso5951.30%220.00%
Patrick McHardy4337.39%440.00%
Julian Anastasov76.09%110.00%
Yasuyuki Kozakai21.74%110.00%
David S. Miller21.74%110.00%
Eric W. Biedermann21.74%110.00%
Total115100.00%10100.00%


static unsigned int ipv4_conntrack_in(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { return nf_conntrack_in(state->net, PF_INET, state->hook, skb); }

Contributors

PersonTokensPropCommitsCommitProp
Yasuyuki Kozakai2463.16%112.50%
Eric W. Biedermann513.16%337.50%
David S. Miller410.53%112.50%
Patrick McHardy25.26%112.50%
Herbert Xu25.26%112.50%
Alexey Dobriyan12.63%112.50%
Total38100.00%8100.00%


static unsigned int ipv4_conntrack_local(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { /* root is playing with raw sockets. */ if (skb->len < sizeof(struct iphdr) || ip_hdrlen(skb) < sizeof(struct iphdr)) return NF_ACCEPT; if (ip_is_fragment(ip_hdr(skb))) /* IP_NODEFRAG setsockopt set */ return NF_ACCEPT; return nf_conntrack_in(state->net, PF_INET, state->hook, skb); }

Contributors

PersonTokensPropCommitsCommitProp
Yasuyuki Kozakai4658.23%110.00%
Florian Westphal1417.72%110.00%
Eric W. Biedermann56.33%330.00%
Herbert Xu45.06%110.00%
David S. Miller45.06%110.00%
Arnaldo Carvalho de Melo33.80%110.00%
Patrick McHardy22.53%110.00%
Alexey Dobriyan11.27%110.00%
Total79100.00%10100.00%

/* Connection tracking may drop packets, but never alters them, so make it the first hook. */ static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = { { .hook = ipv4_conntrack_in, .pf = NFPROTO_IPV4, .hooknum = NF_INET_PRE_ROUTING, .priority = NF_IP_PRI_CONNTRACK, }, { .hook = ipv4_conntrack_local, .pf = NFPROTO_IPV4, .hooknum = NF_INET_LOCAL_OUT, .priority = NF_IP_PRI_CONNTRACK, }, { .hook = ipv4_helper, .pf = NFPROTO_IPV4, .hooknum = NF_INET_POST_ROUTING, .priority = NF_IP_PRI_CONNTRACK_HELPER, }, { .hook = ipv4_confirm, .pf = NFPROTO_IPV4, .hooknum = NF_INET_POST_ROUTING, .priority = NF_IP_PRI_CONNTRACK_CONFIRM, }, { .hook = ipv4_helper, .pf = NFPROTO_IPV4, .hooknum = NF_INET_LOCAL_IN, .priority = NF_IP_PRI_CONNTRACK_HELPER, }, { .hook = ipv4_confirm, .pf = NFPROTO_IPV4, .hooknum = NF_INET_LOCAL_IN, .priority = NF_IP_PRI_CONNTRACK_CONFIRM, }, }; /* Fast function for those who don't want to parse /proc (and I don't blame them). */ /* Reversing the socket's dst/src point of view gives us the reply mapping. */
static int getorigdst(struct sock *sk, int optval, void __user *user, int *len) { const struct inet_sock *inet = inet_sk(sk); const struct nf_conntrack_tuple_hash *h; struct nf_conntrack_tuple tuple; memset(&tuple, 0, sizeof(tuple)); tuple.src.u3.ip = inet->inet_rcv_saddr; tuple.src.u.tcp.port = inet->inet_sport; tuple.dst.u3.ip = inet->inet_daddr; tuple.dst.u.tcp.port = inet->inet_dport; tuple.src.l3num = PF_INET; tuple.dst.protonum = sk->sk_protocol; /* We only do TCP and SCTP at the moment: is there a better way? */ if (sk->sk_protocol != IPPROTO_TCP && sk->sk_protocol != IPPROTO_SCTP) { pr_debug("SO_ORIGINAL_DST: Not a TCP/SCTP socket\n"); return -ENOPROTOOPT; } if ((unsigned int) *len < sizeof(struct sockaddr_in)) { pr_debug("SO_ORIGINAL_DST: len %d not %zu\n", *len, sizeof(struct sockaddr_in)); return -EINVAL; } h = nf_conntrack_find_get(sock_net(sk), &nf_ct_zone_dflt, &tuple); if (h) { struct sockaddr_in sin; struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h); sin.sin_family = AF_INET; sin.sin_port = ct->tuplehash[IP_CT_DIR_ORIGINAL] .tuple.dst.u.tcp.port; sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL] .tuple.dst.u3.ip; memset(sin.sin_zero, 0, sizeof(sin.sin_zero)); pr_debug("SO_ORIGINAL_DST: %pI4 %u\n", &sin.sin_addr.s_addr, ntohs(sin.sin_port)); nf_ct_put(ct); if (copy_to_user(user, &sin, sizeof(sin)) != 0) return -EFAULT; else return 0; } pr_debug("SO_ORIGINAL_DST: Can't find %pI4/%u-%pI4/%u.\n", &tuple.src.u3.ip, ntohs(tuple.src.u.tcp.port), &tuple.dst.u3.ip, ntohs(tuple.dst.u.tcp.port)); return -ENOENT; }

Contributors

PersonTokensPropCommitsCommitProp
Yasuyuki Kozakai32984.36%18.33%
Marcel Holtmann164.10%18.33%
Rafael Laufer133.33%18.33%
Philip Craig82.05%18.33%
Alexey Dobriyan61.54%216.67%
Harvey Harrison51.28%18.33%
Patrick McHardy51.28%216.67%
Eric Dumazet41.03%18.33%
Jan Engelhardt20.51%18.33%
Daniel Borkmann20.51%18.33%
Total390100.00%12100.00%

#if IS_ENABLED(CONFIG_NF_CT_NETLINK) #include <linux/netfilter/nfnetlink.h> #include <linux/netfilter/nfnetlink_conntrack.h>
static int ipv4_tuple_to_nlattr(struct sk_buff *skb, const struct nf_conntrack_tuple *tuple) { if (nla_put_in_addr(skb, CTA_IP_V4_SRC, tuple->src.u3.ip) || nla_put_in_addr(skb, CTA_IP_V4_DST, tuple->dst.u3.ip)) goto nla_put_failure; return 0; nla_put_failure: return -1; }

Contributors

PersonTokensPropCommitsCommitProp
Pablo Neira Ayuso5081.97%120.00%
David S. Miller711.48%120.00%
Jiri Benc23.28%120.00%
Patrick McHardy23.28%240.00%
Total61100.00%5100.00%

static const struct nla_policy ipv4_nla_policy[CTA_IP_MAX+1] = { [CTA_IP_V4_SRC] = { .type = NLA_U32 }, [CTA_IP_V4_DST] = { .type = NLA_U32 }, };
static int ipv4_nlattr_to_tuple(struct nlattr *tb[], struct nf_conntrack_tuple *t) { if (!tb[CTA_IP_V4_SRC] || !tb[CTA_IP_V4_DST]) return -EINVAL; t->src.u3.ip = nla_get_in_addr(tb[CTA_IP_V4_SRC]); t->dst.u3.ip = nla_get_in_addr(tb[CTA_IP_V4_DST]); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Pablo Neira Ayuso6694.29%125.00%
Jiri Benc22.86%125.00%
Patrick McHardy22.86%250.00%
Total70100.00%4100.00%


static int ipv4_nlattr_tuple_size(void) { return nla_policy_len(ipv4_nla_policy, CTA_IP_MAX + 1); }

Contributors

PersonTokensPropCommitsCommitProp
Holger Eitzenberger18100.00%1100.00%
Total18100.00%1100.00%

#endif static struct nf_sockopt_ops so_getorigdst = { .pf = PF_INET, .get_optmin = SO_ORIGINAL_DST, .get_optmax = SO_ORIGINAL_DST+1, .get = getorigdst, .owner = THIS_MODULE, };
static int ipv4_hooks_register(struct net *net) { struct conntrack4_net *cnet = net_generic(net, conntrack4_net_id); int err = 0; mutex_lock(&register_ipv4_hooks); cnet->users++; if (cnet->users > 1) goto out_unlock; err = nf_defrag_ipv4_enable(net); if (err) { cnet->users = 0; goto out_unlock; } err = nf_register_net_hooks(net, ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops)); if (err) cnet->users = 0; out_unlock: mutex_unlock(&register_ipv4_hooks); return err; }

Contributors

PersonTokensPropCommitsCommitProp
Florian Westphal107100.00%2100.00%
Total107100.00%2100.00%


static void ipv4_hooks_unregister(struct net *net) { struct conntrack4_net *cnet = net_generic(net, conntrack4_net_id); mutex_lock(&register_ipv4_hooks); if (cnet->users && (--cnet->users == 0)) nf_unregister_net_hooks(net, ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops)); mutex_unlock(&register_ipv4_hooks); }

Contributors

PersonTokensPropCommitsCommitProp
Florian Westphal62100.00%1100.00%
Total62100.00%1100.00%

struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = { .l3proto = PF_INET, .name = "ipv4", .pkt_to_tuple = ipv4_pkt_to_tuple, .invert_tuple = ipv4_invert_tuple, .print_tuple = ipv4_print_tuple, .get_l4proto = ipv4_get_l4proto, #if IS_ENABLED(CONFIG_NF_CT_NETLINK) .tuple_to_nlattr = ipv4_tuple_to_nlattr, .nlattr_tuple_size = ipv4_nlattr_tuple_size, .nlattr_to_tuple = ipv4_nlattr_to_tuple, .nla_policy = ipv4_nla_policy, #endif .net_ns_get = ipv4_hooks_register, .net_ns_put = ipv4_hooks_unregister, .me = THIS_MODULE, }; module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint, &nf_conntrack_htable_size, 0600); MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET)); MODULE_ALIAS("ip_conntrack"); MODULE_LICENSE("GPL"); static struct nf_conntrack_l4proto *builtin_l4proto4[] = { &nf_conntrack_l4proto_tcp4, &nf_conntrack_l4proto_udp4, &nf_conntrack_l4proto_icmp, #ifdef CONFIG_NF_CT_PROTO_DCCP &nf_conntrack_l4proto_dccp4, #endif #ifdef CONFIG_NF_CT_PROTO_SCTP &nf_conntrack_l4proto_sctp4, #endif #ifdef CONFIG_NF_CT_PROTO_UDPLITE &nf_conntrack_l4proto_udplite4, #endif };
static int ipv4_net_init(struct net *net) { int ret = 0; ret = nf_ct_l4proto_pernet_register(net, builtin_l4proto4, ARRAY_SIZE(builtin_l4proto4)); if (ret < 0) return ret; ret = nf_ct_l3proto_pernet_register(net, &nf_conntrack_l3proto_ipv4); if (ret < 0) { pr_err("nf_conntrack_ipv4: pernet registration failed\n"); nf_ct_l4proto_pernet_unregister(net, builtin_l4proto4, ARRAY_SIZE(builtin_l4proto4)); } return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Yasuyuki Kozakai3950.65%114.29%
Gao Feng2633.77%457.14%
Davide Caratti1114.29%114.29%
Stephen Hemminger11.30%114.29%
Total77100.00%7100.00%


static void ipv4_net_exit(struct net *net) { nf_ct_l3proto_pernet_unregister(net, &nf_conntrack_l3proto_ipv4); nf_ct_l4proto_pernet_unregister(net, builtin_l4proto4, ARRAY_SIZE(builtin_l4proto4)); }

Contributors

PersonTokensPropCommitsCommitProp
Gao Feng2477.42%466.67%
Davide Caratti412.90%116.67%
Yasuyuki Kozakai39.68%116.67%
Total31100.00%6100.00%

static struct pernet_operations ipv4_net_ops = { .init = ipv4_net_init, .exit = ipv4_net_exit, .id = &conntrack4_net_id, .size = sizeof(struct conntrack4_net), };
static int __init nf_conntrack_l3proto_ipv4_init(void) { int ret = 0; need_conntrack(); ret = nf_register_sockopt(&so_getorigdst); if (ret < 0) { pr_err("Unable to register netfilter socket option\n"); return ret; } ret = register_pernet_subsys(&ipv4_net_ops); if (ret < 0) { pr_err("nf_conntrack_ipv4: can't register pernet ops\n"); goto cleanup_sockopt; } ret = nf_ct_l4proto_register(builtin_l4proto4, ARRAY_SIZE(builtin_l4proto4)); if (ret < 0) goto cleanup_pernet; ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv4); if (ret < 0) { pr_err("nf_conntrack_ipv4: can't register ipv4 proto.\n"); goto cleanup_l4proto; } return ret; cleanup_l4proto: nf_ct_l4proto_unregister(builtin_l4proto4, ARRAY_SIZE(builtin_l4proto4)); cleanup_pernet: unregister_pernet_subsys(&ipv4_net_ops); cleanup_sockopt: nf_unregister_sockopt(&so_getorigdst); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Gao Feng9666.67%337.50%
Yasuyuki Kozakai3524.31%112.50%
Davide Caratti106.94%112.50%
Bastian Stender10.69%112.50%
Stephen Hemminger10.69%112.50%
Florian Westphal10.69%112.50%
Total144100.00%8100.00%


static void __exit nf_conntrack_l3proto_ipv4_fini(void) { synchronize_net(); nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv4); nf_ct_l4proto_unregister(builtin_l4proto4, ARRAY_SIZE(builtin_l4proto4)); unregister_pernet_subsys(&ipv4_net_ops); nf_unregister_sockopt(&so_getorigdst); }

Contributors

PersonTokensPropCommitsCommitProp
Patrick McHardy1845.00%116.67%
Gao Feng1435.00%350.00%
Davide Caratti410.00%116.67%
Yasuyuki Kozakai410.00%116.67%
Total40100.00%6100.00%

module_init(nf_conntrack_l3proto_ipv4_init); module_exit(nf_conntrack_l3proto_ipv4_fini);

Overall Contributors

PersonTokensPropCommitsCommitProp
Yasuyuki Kozakai100245.82%22.53%
Pablo Neira Ayuso27412.53%45.06%
Florian Westphal22910.47%33.80%
Patrick McHardy1908.69%2430.38%
Gao Feng1778.09%56.33%
Davide Caratti723.29%45.06%
Jozsef Kadlecsik361.65%22.53%
Jan Engelhardt231.05%33.80%
Holger Eitzenberger231.05%11.27%
David S. Miller190.87%22.53%
Harald Welte180.82%11.27%
Marcel Holtmann160.73%11.27%
Eric W. Biedermann140.64%33.80%
Rafael Laufer130.59%11.27%
Herbert Xu110.50%11.27%
Arnaldo Carvalho de Melo90.41%22.53%
Harvey Harrison80.37%11.27%
Alexey Dobriyan80.37%33.80%
Philip Craig80.37%11.27%
Julian Anastasov70.32%11.27%
Neil Horman50.23%11.27%
Eric Dumazet50.23%22.53%
Jiri Benc40.18%22.53%
KOVACS Krisztian30.14%11.27%
Joe Perches20.09%11.27%
Duan Jiong20.09%11.27%
Stephen Hemminger20.09%11.27%
Daniel Borkmann20.09%11.27%
Andrew Morton20.09%11.27%
Bastian Stender10.05%11.27%
Martin Josefsson10.05%11.27%
Aaron Conole10.05%11.27%
Total2187100.00%79100.00%
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