| /* IP tables module for matching IPsec policy |
| * |
| * Copyright (c) 2004,2005 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/kernel.h> |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/init.h> |
| #include <net/xfrm.h> |
| |
| #include <linux/netfilter/xt_policy.h> |
| #include <linux/netfilter/x_tables.h> |
| |
| MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); |
| MODULE_DESCRIPTION("Xtables IPsec policy matching module"); |
| MODULE_LICENSE("GPL"); |
| |
| static inline bool |
| xt_addr_cmp(const union xt_policy_addr *a1, const union xt_policy_addr *m, |
| const union xt_policy_addr *a2, unsigned short family) |
| { |
| switch (family) { |
| case AF_INET: |
| return !((a1->a4.s_addr ^ a2->a4.s_addr) & m->a4.s_addr); |
| case AF_INET6: |
| return !ipv6_masked_addr_cmp(&a1->a6, &m->a6, &a2->a6); |
| } |
| return false; |
| } |
| |
| static inline bool |
| match_xfrm_state(struct xfrm_state *x, const struct xt_policy_elem *e, |
| unsigned short family) |
| { |
| #define MATCH_ADDR(x,y,z) (!e->match.x || \ |
| (xt_addr_cmp(&e->x, &e->y, z, family) \ |
| ^ e->invert.x)) |
| #define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x)) |
| |
| return MATCH_ADDR(saddr, smask, (union xt_policy_addr *)&x->props.saddr) && |
| MATCH_ADDR(daddr, dmask, (union xt_policy_addr *)&x->id.daddr) && |
| MATCH(proto, x->id.proto) && |
| MATCH(mode, x->props.mode) && |
| MATCH(spi, x->id.spi) && |
| MATCH(reqid, x->props.reqid); |
| } |
| |
| static int |
| match_policy_in(const struct sk_buff *skb, const struct xt_policy_info *info, |
| unsigned short family) |
| { |
| const struct xt_policy_elem *e; |
| struct sec_path *sp = skb->sp; |
| int strict = info->flags & XT_POLICY_MATCH_STRICT; |
| int i, pos; |
| |
| if (sp == NULL) |
| return -1; |
| if (strict && info->len != sp->len) |
| return 0; |
| |
| for (i = sp->len - 1; i >= 0; i--) { |
| pos = strict ? i - sp->len + 1 : 0; |
| if (pos >= info->len) |
| return 0; |
| e = &info->pol[pos]; |
| |
| if (match_xfrm_state(sp->xvec[i], e, family)) { |
| if (!strict) |
| return 1; |
| } else if (strict) |
| return 0; |
| } |
| |
| return strict ? 1 : 0; |
| } |
| |
| static int |
| match_policy_out(const struct sk_buff *skb, const struct xt_policy_info *info, |
| unsigned short family) |
| { |
| const struct xt_policy_elem *e; |
| struct dst_entry *dst = skb->dst; |
| int strict = info->flags & XT_POLICY_MATCH_STRICT; |
| int i, pos; |
| |
| if (dst->xfrm == NULL) |
| return -1; |
| |
| for (i = 0; dst && dst->xfrm; dst = dst->child, i++) { |
| pos = strict ? i : 0; |
| if (pos >= info->len) |
| return 0; |
| e = &info->pol[pos]; |
| |
| if (match_xfrm_state(dst->xfrm, e, family)) { |
| if (!strict) |
| return 1; |
| } else if (strict) |
| return 0; |
| } |
| |
| return strict ? i == info->len : 0; |
| } |
| |
| 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_policy_info *info = matchinfo; |
| int ret; |
| |
| if (info->flags & XT_POLICY_MATCH_IN) |
| ret = match_policy_in(skb, info, match->family); |
| else |
| ret = match_policy_out(skb, info, match->family); |
| |
| if (ret < 0) |
| ret = info->flags & XT_POLICY_MATCH_NONE ? true : false; |
| else if (info->flags & XT_POLICY_MATCH_NONE) |
| ret = false; |
| |
| return ret; |
| } |
| |
| static int checkentry(const char *tablename, const void *ip_void, |
| const struct xt_match *match, |
| void *matchinfo, unsigned int hook_mask) |
| { |
| struct xt_policy_info *info = matchinfo; |
| |
| if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT))) { |
| printk(KERN_ERR "xt_policy: neither incoming nor " |
| "outgoing policy selected\n"); |
| return 0; |
| } |
| /* hook values are equal for IPv4 and IPv6 */ |
| if (hook_mask & (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_LOCAL_IN) |
| && info->flags & XT_POLICY_MATCH_OUT) { |
| printk(KERN_ERR "xt_policy: output policy not valid in " |
| "PRE_ROUTING and INPUT\n"); |
| return 0; |
| } |
| if (hook_mask & (1 << NF_IP_POST_ROUTING | 1 << NF_IP_LOCAL_OUT) |
| && info->flags & XT_POLICY_MATCH_IN) { |
| printk(KERN_ERR "xt_policy: input policy not valid in " |
| "POST_ROUTING and OUTPUT\n"); |
| return 0; |
| } |
| if (info->len > XT_POLICY_MAX_ELEM) { |
| printk(KERN_ERR "xt_policy: too many policy elements\n"); |
| return 0; |
| } |
| return 1; |
| } |
| |
| static struct xt_match xt_policy_match[] = { |
| { |
| .name = "policy", |
| .family = AF_INET, |
| .checkentry = checkentry, |
| .match = match, |
| .matchsize = sizeof(struct xt_policy_info), |
| .me = THIS_MODULE, |
| }, |
| { |
| .name = "policy", |
| .family = AF_INET6, |
| .checkentry = checkentry, |
| .match = match, |
| .matchsize = sizeof(struct xt_policy_info), |
| .me = THIS_MODULE, |
| }, |
| }; |
| |
| static int __init init(void) |
| { |
| return xt_register_matches(xt_policy_match, |
| ARRAY_SIZE(xt_policy_match)); |
| } |
| |
| static void __exit fini(void) |
| { |
| xt_unregister_matches(xt_policy_match, ARRAY_SIZE(xt_policy_match)); |
| } |
| |
| module_init(init); |
| module_exit(fini); |
| MODULE_ALIAS("ipt_policy"); |
| MODULE_ALIAS("ip6t_policy"); |