--- /dev/null
+/*
+ * iptables module for DCCP protocol header matching
+ *
+ * (C) 2005 by Harald Welte <laforge@netfilter.org>
+ *
+ * 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/spinlock.h>
+#include <net/ip.h>
+#include <linux/dccp.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_dccp.h>
+
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv6/ip6_tables.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
+MODULE_DESCRIPTION("Match for DCCP protocol packets");
+MODULE_ALIAS("ipt_dccp");
+
+#define DCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \
+ || (!!((invflag) & (option)) ^ (cond)))
+
+static unsigned char *dccp_optbuf;
+static DEFINE_SPINLOCK(dccp_buflock);
+
+static inline int
+dccp_find_option(u_int8_t option,
+ const struct sk_buff *skb,
+ unsigned int protoff,
+ const struct dccp_hdr *dh,
+ int *hotdrop)
+{
+ /* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */
+ unsigned char *op;
+ unsigned int optoff = __dccp_hdr_len(dh);
+ unsigned int optlen = dh->dccph_doff*4 - __dccp_hdr_len(dh);
+ unsigned int i;
+
+ if (dh->dccph_doff * 4 < __dccp_hdr_len(dh)) {
+ *hotdrop = 1;
+ return 0;
+ }
+
+ if (!optlen)
+ return 0;
+
+ spin_lock_bh(&dccp_buflock);
+ op = skb_header_pointer(skb, protoff + optoff, optlen, dccp_optbuf);
+ if (op == NULL) {
+ /* If we don't have the whole header, drop packet. */
+ spin_unlock_bh(&dccp_buflock);
+ *hotdrop = 1;
+ return 0;
+ }
+
+ for (i = 0; i < optlen; ) {
+ if (op[i] == option) {
+ spin_unlock_bh(&dccp_buflock);
+ return 1;
+ }
+
+ if (op[i] < 2)
+ i++;
+ else
+ i += op[i+1]?:1;
+ }
+
+ spin_unlock_bh(&dccp_buflock);
+ return 0;
+}
+
+
+static inline int
+match_types(const struct dccp_hdr *dh, u_int16_t typemask)
+{
+ return (typemask & (1 << dh->dccph_type));
+}
+
+static inline int
+match_option(u_int8_t option, const struct sk_buff *skb, unsigned int protoff,
+ const struct dccp_hdr *dh, int *hotdrop)
+{
+ return dccp_find_option(option, skb, protoff, dh, hotdrop);
+}
+
+static int
+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,
+ int *hotdrop)
+{
+ const struct xt_dccp_info *info =
+ (const struct xt_dccp_info *)matchinfo;
+ struct dccp_hdr _dh, *dh;
+
+ if (offset)
+ return 0;
+
+ dh = skb_header_pointer(skb, protoff, sizeof(_dh), &_dh);
+ if (dh == NULL) {
+ *hotdrop = 1;
+ return 0;
+ }
+
+ return DCCHECK(((ntohs(dh->dccph_sport) >= info->spts[0])
+ && (ntohs(dh->dccph_sport) <= info->spts[1])),
+ XT_DCCP_SRC_PORTS, info->flags, info->invflags)
+ && DCCHECK(((ntohs(dh->dccph_dport) >= info->dpts[0])
+ && (ntohs(dh->dccph_dport) <= info->dpts[1])),
+ XT_DCCP_DEST_PORTS, info->flags, info->invflags)
+ && DCCHECK(match_types(dh, info->typemask),
+ XT_DCCP_TYPE, info->flags, info->invflags)
+ && DCCHECK(match_option(info->option, skb, protoff, dh,
+ hotdrop),
+ XT_DCCP_OPTION, info->flags, info->invflags);
+}
+
+static int
+checkentry(const char *tablename,
+ const void *inf,
+ const struct xt_match *match,
+ void *matchinfo,
+ unsigned int matchsize,
+ unsigned int hook_mask)
+{
+ const struct xt_dccp_info *info = matchinfo;
+
+ return !(info->flags & ~XT_DCCP_VALID_FLAGS)
+ && !(info->invflags & ~XT_DCCP_VALID_FLAGS)
+ && !(info->invflags & ~info->flags);
+}
+
+static struct xt_match dccp_match =
+{
+ .name = "dccp",
+ .match = match,
+ .matchsize = sizeof(struct xt_dccp_info),
+ .proto = IPPROTO_DCCP,
+ .checkentry = checkentry,
+ .family = AF_INET,
+ .me = THIS_MODULE,
+};
+static struct xt_match dccp6_match =
+{
+ .name = "dccp",
+ .match = match,
+ .matchsize = sizeof(struct xt_dccp_info),
+ .proto = IPPROTO_DCCP,
+ .checkentry = checkentry,
+ .family = AF_INET6,
+ .me = THIS_MODULE,
+};
+
+
+static int __init xt_dccp_init(void)
+{
+ int ret;
+
+ /* doff is 8 bits, so the maximum option size is (4*256). Don't put
+ * this in BSS since DaveM is worried about locked TLB's for kernel
+ * BSS. */
+ dccp_optbuf = kmalloc(256 * 4, GFP_KERNEL);
+ if (!dccp_optbuf)
+ return -ENOMEM;
+ ret = xt_register_match(&dccp_match);
+ if (ret)
+ goto out_kfree;
+ ret = xt_register_match(&dccp6_match);
+ if (ret)
+ goto out_unreg;
+
+ return ret;
+
+out_unreg:
+ xt_unregister_match(&dccp_match);
+out_kfree:
+ kfree(dccp_optbuf);
+
+ return ret;
+}
+
+static void __exit xt_dccp_fini(void)
+{
+ xt_unregister_match(&dccp6_match);
+ xt_unregister_match(&dccp_match);
+ kfree(dccp_optbuf);
+}
+
+module_init(xt_dccp_init);
+module_exit(xt_dccp_fini);
git://git.onelab.eu / linux-2.6.git / blobdiff