diff options
Diffstat (limited to 'net/ipv4/netfilter/ipt_policy.c')
| -rw-r--r-- | net/ipv4/netfilter/ipt_policy.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/ipt_policy.c b/net/ipv4/netfilter/ipt_policy.c new file mode 100644 index 0000000000000..709debcc69c92 --- /dev/null +++ b/net/ipv4/netfilter/ipt_policy.c @@ -0,0 +1,170 @@ +/* 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/config.h> +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/init.h> +#include <net/xfrm.h> + +#include <linux/netfilter_ipv4.h> +#include <linux/netfilter_ipv4/ip_tables.h> +#include <linux/netfilter_ipv4/ipt_policy.h> + +MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); +MODULE_DESCRIPTION("IPtables IPsec policy matching module"); +MODULE_LICENSE("GPL"); + + +static inline int +match_xfrm_state(struct xfrm_state *x, const struct ipt_policy_elem *e) +{ +#define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x)) + + return MATCH(saddr, x->props.saddr.a4 & e->smask) && + MATCH(daddr, x->id.daddr.a4 & e->dmask) && + 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 ipt_policy_info *info) +{ + const struct ipt_policy_elem *e; + struct sec_path *sp = skb->sp; + int strict = info->flags & IPT_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->x[i].xvec, e)) { + 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 ipt_policy_info *info) +{ + const struct ipt_policy_elem *e; + struct dst_entry *dst = skb->dst; + int strict = info->flags & IPT_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)) { + if (!strict) + return 1; + } else if (strict) + return 0; + } + + return strict ? 1 : 0; +} + +static int match(const struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + const void *matchinfo, int offset, int *hotdrop) +{ + const struct ipt_policy_info *info = matchinfo; + int ret; + + if (info->flags & IPT_POLICY_MATCH_IN) + ret = match_policy_in(skb, info); + else + ret = match_policy_out(skb, info); + + if (ret < 0) + ret = info->flags & IPT_POLICY_MATCH_NONE ? 1 : 0; + else if (info->flags & IPT_POLICY_MATCH_NONE) + ret = 0; + + return ret; +} + +static int checkentry(const char *tablename, const struct ipt_ip *ip, + void *matchinfo, unsigned int matchsize, + unsigned int hook_mask) +{ + struct ipt_policy_info *info = matchinfo; + + if (matchsize != IPT_ALIGN(sizeof(*info))) { + printk(KERN_ERR "ipt_policy: matchsize %u != %zu\n", + matchsize, IPT_ALIGN(sizeof(*info))); + return 0; + } + if (!(info->flags & (IPT_POLICY_MATCH_IN|IPT_POLICY_MATCH_OUT))) { + printk(KERN_ERR "ipt_policy: neither incoming nor " + "outgoing policy selected\n"); + return 0; + } + if (hook_mask & (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_LOCAL_IN) + && info->flags & IPT_POLICY_MATCH_OUT) { + printk(KERN_ERR "ipt_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 & IPT_POLICY_MATCH_IN) { + printk(KERN_ERR "ipt_policy: input policy not valid in " + "POST_ROUTING and OUTPUT\n"); + return 0; + } + if (info->len > IPT_POLICY_MAX_ELEM) { + printk(KERN_ERR "ipt_policy: too many policy elements\n"); + return 0; + } + + return 1; +} + +static struct ipt_match policy_match = { + .name = "policy", + .match = match, + .checkentry = checkentry, + .me = THIS_MODULE, +}; + +static int __init init(void) +{ + return ipt_register_match(&policy_match); +} + +static void __exit fini(void) +{ + ipt_unregister_match(&policy_match); +} + +module_init(init); +module_exit(fini); |