--- /dev/null
+/* 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.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/init.h>
+#include <net/xfrm.h>
+
+#include <linux/netfilter.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 match");
+MODULE_LICENSE("GPL");
+
+static inline bool
+xt_addr_cmp(const union nf_inet_addr *a1, const union nf_inet_addr *m,
+ const union nf_inet_addr *a2, unsigned short family)
+{
+ switch (family) {
+ case NFPROTO_IPV4:
+ return ((a1->ip ^ a2->ip) & m->ip) == 0;
+ case NFPROTO_IPV6:
+ return ipv6_masked_addr_cmp(&a1->in6, &m->in6, &a2->in6) == 0;
+ }
+ return false;
+}
+
+static bool
+match_xfrm_state(const 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, (const union nf_inet_addr *)(z), family) \
+ ^ e->invert.x))
+#define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x))
+
+ return MATCH_ADDR(saddr, smask, &x->props.saddr) &&
+ MATCH_ADDR(daddr, dmask, &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;
+ const 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;
+ const struct dst_entry *dst = skb_dst(skb);
+ 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
+policy_mt(const struct sk_buff *skb, struct xt_action_param *par)
+{
+ const struct xt_policy_info *info = par->matchinfo;
+ int ret;
+
+ if (info->flags & XT_POLICY_MATCH_IN)
+ ret = match_policy_in(skb, info, par->family);
+ else
+ ret = match_policy_out(skb, info, par->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 policy_mt_check(const struct xt_mtchk_param *par)
+{
+ const struct xt_policy_info *info = par->matchinfo;
+
+ if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT))) {
+ pr_info("neither incoming nor outgoing policy selected\n");
+ return -EINVAL;
+ }
+ if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_LOCAL_IN)) && info->flags & XT_POLICY_MATCH_OUT) {
+ pr_info("output policy not valid in PREROUTING and INPUT\n");
+ return -EINVAL;
+ }
+ if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
+ (1 << NF_INET_LOCAL_OUT)) && info->flags & XT_POLICY_MATCH_IN) {
+ pr_info("input policy not valid in POSTROUTING and OUTPUT\n");
+ return -EINVAL;
+ }
+ if (info->len > XT_POLICY_MAX_ELEM) {
+ pr_info("too many policy elements\n");
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static struct xt_match policy_mt_reg[] __read_mostly = {
+ {
+ .name = "policy",
+ .family = NFPROTO_IPV4,
+ .checkentry = policy_mt_check,
+ .match = policy_mt,
+ .matchsize = sizeof(struct xt_policy_info),
+ .me = THIS_MODULE,
+ },
+ {
+ .name = "policy",
+ .family = NFPROTO_IPV6,
+ .checkentry = policy_mt_check,
+ .match = policy_mt,
+ .matchsize = sizeof(struct xt_policy_info),
+ .me = THIS_MODULE,
+ },
+};
+
+static int __init policy_mt_init(void)
+{
+ return xt_register_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
+}
+
+static void __exit policy_mt_exit(void)
+{
+ xt_unregister_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
+}
+
+module_init(policy_mt_init);
+module_exit(policy_mt_exit);
+MODULE_ALIAS("ipt_policy");
+MODULE_ALIAS("ip6t_policy");
Code Review / kvmfornfv.git / blobdiff