| /* Kernel module to match connection tracking information. |
| * Superset of Rusty's minimalistic state match. |
| * |
| * (C) 2001 Marc Boucher (marc@mbsi.ca). |
| * |
| * 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/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/netfilter/x_tables.h> |
| #include <linux/netfilter/xt_conntrack.h> |
| #include <net/netfilter/nf_conntrack.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>"); |
| MODULE_DESCRIPTION("iptables connection tracking match module"); |
| MODULE_ALIAS("ipt_conntrack"); |
| |
| static bool |
| match(const struct sk_buff *skb, |
| const struct net_device *in, |
| const struct net_device *out, |
| const struct xt_match *match, |
| const void *matchinfo, |
| int offset, |
| unsigned int protoff, |
| bool *hotdrop) |
| { |
| const struct xt_conntrack_info *sinfo = matchinfo; |
| struct nf_conn *ct; |
| enum ip_conntrack_info ctinfo; |
| unsigned int statebit; |
| |
| ct = nf_ct_get((struct sk_buff *)skb, &ctinfo); |
| |
| #define FWINV(bool,invflg) ((bool) ^ !!(sinfo->invflags & invflg)) |
| |
| if (ct == &nf_conntrack_untracked) |
| statebit = XT_CONNTRACK_STATE_UNTRACKED; |
| else if (ct) |
| statebit = XT_CONNTRACK_STATE_BIT(ctinfo); |
| else |
| statebit = XT_CONNTRACK_STATE_INVALID; |
| |
| if (sinfo->flags & XT_CONNTRACK_STATE) { |
| if (ct) { |
| if (test_bit(IPS_SRC_NAT_BIT, &ct->status)) |
| statebit |= XT_CONNTRACK_STATE_SNAT; |
| if (test_bit(IPS_DST_NAT_BIT, &ct->status)) |
| statebit |= XT_CONNTRACK_STATE_DNAT; |
| } |
| if (FWINV((statebit & sinfo->statemask) == 0, |
| XT_CONNTRACK_STATE)) |
| return false; |
| } |
| |
| if (ct == NULL) { |
| if (sinfo->flags & ~XT_CONNTRACK_STATE) |
| return false; |
| return true; |
| } |
| |
| if (sinfo->flags & XT_CONNTRACK_PROTO && |
| FWINV(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum != |
| sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.protonum, |
| XT_CONNTRACK_PROTO)) |
| return false; |
| |
| if (sinfo->flags & XT_CONNTRACK_ORIGSRC && |
| FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip & |
| sinfo->sipmsk[IP_CT_DIR_ORIGINAL].s_addr) != |
| sinfo->tuple[IP_CT_DIR_ORIGINAL].src.ip, |
| XT_CONNTRACK_ORIGSRC)) |
| return false; |
| |
| if (sinfo->flags & XT_CONNTRACK_ORIGDST && |
| FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip & |
| sinfo->dipmsk[IP_CT_DIR_ORIGINAL].s_addr) != |
| sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.ip, |
| XT_CONNTRACK_ORIGDST)) |
| return false; |
| |
| if (sinfo->flags & XT_CONNTRACK_REPLSRC && |
| FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip & |
| sinfo->sipmsk[IP_CT_DIR_REPLY].s_addr) != |
| sinfo->tuple[IP_CT_DIR_REPLY].src.ip, |
| XT_CONNTRACK_REPLSRC)) |
| return false; |
| |
| if (sinfo->flags & XT_CONNTRACK_REPLDST && |
| FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip & |
| sinfo->dipmsk[IP_CT_DIR_REPLY].s_addr) != |
| sinfo->tuple[IP_CT_DIR_REPLY].dst.ip, |
| XT_CONNTRACK_REPLDST)) |
| return false; |
| |
| if (sinfo->flags & XT_CONNTRACK_STATUS && |
| FWINV((ct->status & sinfo->statusmask) == 0, |
| XT_CONNTRACK_STATUS)) |
| return false; |
| |
| if(sinfo->flags & XT_CONNTRACK_EXPIRES) { |
| unsigned long expires = timer_pending(&ct->timeout) ? |
| (ct->timeout.expires - jiffies)/HZ : 0; |
| |
| if (FWINV(!(expires >= sinfo->expires_min && |
| expires <= sinfo->expires_max), |
| XT_CONNTRACK_EXPIRES)) |
| return false; |
| } |
| return true; |
| } |
| |
| static int |
| checkentry(const char *tablename, |
| const void *ip, |
| const struct xt_match *match, |
| void *matchinfo, |
| unsigned int hook_mask) |
| { |
| if (nf_ct_l3proto_try_module_get(match->family) < 0) { |
| printk(KERN_WARNING "can't load conntrack support for " |
| "proto=%d\n", match->family); |
| return 0; |
| } |
| return 1; |
| } |
| |
| static void destroy(const struct xt_match *match, void *matchinfo) |
| { |
| nf_ct_l3proto_module_put(match->family); |
| } |
| |
| #ifdef CONFIG_COMPAT |
| struct compat_xt_conntrack_info |
| { |
| compat_uint_t statemask; |
| compat_uint_t statusmask; |
| struct ip_conntrack_old_tuple tuple[IP_CT_DIR_MAX]; |
| struct in_addr sipmsk[IP_CT_DIR_MAX]; |
| struct in_addr dipmsk[IP_CT_DIR_MAX]; |
| compat_ulong_t expires_min; |
| compat_ulong_t expires_max; |
| u_int8_t flags; |
| u_int8_t invflags; |
| }; |
| |
| static void compat_from_user(void *dst, void *src) |
| { |
| struct compat_xt_conntrack_info *cm = src; |
| struct xt_conntrack_info m = { |
| .statemask = cm->statemask, |
| .statusmask = cm->statusmask, |
| .expires_min = cm->expires_min, |
| .expires_max = cm->expires_max, |
| .flags = cm->flags, |
| .invflags = cm->invflags, |
| }; |
| memcpy(m.tuple, cm->tuple, sizeof(m.tuple)); |
| memcpy(m.sipmsk, cm->sipmsk, sizeof(m.sipmsk)); |
| memcpy(m.dipmsk, cm->dipmsk, sizeof(m.dipmsk)); |
| memcpy(dst, &m, sizeof(m)); |
| } |
| |
| static int compat_to_user(void __user *dst, void *src) |
| { |
| struct xt_conntrack_info *m = src; |
| struct compat_xt_conntrack_info cm = { |
| .statemask = m->statemask, |
| .statusmask = m->statusmask, |
| .expires_min = m->expires_min, |
| .expires_max = m->expires_max, |
| .flags = m->flags, |
| .invflags = m->invflags, |
| }; |
| memcpy(cm.tuple, m->tuple, sizeof(cm.tuple)); |
| memcpy(cm.sipmsk, m->sipmsk, sizeof(cm.sipmsk)); |
| memcpy(cm.dipmsk, m->dipmsk, sizeof(cm.dipmsk)); |
| return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0; |
| } |
| #endif |
| |
| static struct xt_match conntrack_match = { |
| .name = "conntrack", |
| .match = match, |
| .checkentry = checkentry, |
| .destroy = destroy, |
| .matchsize = sizeof(struct xt_conntrack_info), |
| #ifdef CONFIG_COMPAT |
| .compatsize = sizeof(struct compat_xt_conntrack_info), |
| .compat_from_user = compat_from_user, |
| .compat_to_user = compat_to_user, |
| #endif |
| .family = AF_INET, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init xt_conntrack_init(void) |
| { |
| return xt_register_match(&conntrack_match); |
| } |
| |
| static void __exit xt_conntrack_fini(void) |
| { |
| xt_unregister_match(&conntrack_match); |
| } |
| |
| module_init(xt_conntrack_init); |
| module_exit(xt_conntrack_fini); |