#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
-#define TH_SYN 0x02
-
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
MODULE_DESCRIPTION("iptables TCP MSS match module");
MODULE_ALIAS("ipt_tcpmss");
-/* Returns 1 if the mss option is set and matched by the range, 0 otherwise */
-static inline int
-mssoption_match(u_int16_t min, u_int16_t max,
- const struct sk_buff *skb,
- unsigned int protoff,
- int invert,
- int *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_tcpmss_match_info *info = matchinfo;
struct tcphdr _tcph, *th;
/* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */
u8 _opt[15 * 4 - sizeof(_tcph)], *op;
mssval = (op[i+2] << 8) | op[i+3];
- return (mssval >= min && mssval <= max) ^ invert;
+ return (mssval >= info->mss_min &&
+ mssval <= info->mss_max) ^ info->invert;
}
- if (op[i] < 2) i++;
- else i += op[i+1]?:1;
+ if (op[i] < 2)
+ i++;
+ else
+ i += op[i+1] ? : 1;
}
out:
- return invert;
+ return info->invert;
- dropit:
+dropit:
*hotdrop = 1;
return 0;
}
-static int
-match(const struct sk_buff *skb,
- const struct net_device *in,
- const struct net_device *out,
- const void *matchinfo,
- int offset,
- unsigned int protoff,
- int *hotdrop)
-{
- const struct xt_tcpmss_match_info *info = matchinfo;
-
- return mssoption_match(info->mss_min, info->mss_max, skb, protoff,
- info->invert, hotdrop);
-}
-
-static int
-checkentry(const char *tablename,
- const void *ipinfo,
- void *matchinfo,
- unsigned int matchsize,
- unsigned int hook_mask)
-{
- const struct ipt_ip *ip = ipinfo;
- if (matchsize != XT_ALIGN(sizeof(struct xt_tcpmss_match_info)))
- return 0;
-
- /* Must specify -p tcp */
- if (ip->proto != IPPROTO_TCP || (ip->invflags & IPT_INV_PROTO)) {
- printk("tcpmss: Only works on TCP packets\n");
- return 0;
- }
-
- return 1;
-}
-
-static int
-checkentry6(const char *tablename,
- const void *ipinfo,
- void *matchinfo,
- unsigned int matchsize,
- unsigned int hook_mask)
-{
- const struct ip6t_ip6 *ip = ipinfo;
-
- if (matchsize != XT_ALIGN(sizeof(struct xt_tcpmss_match_info)))
- return 0;
-
- /* Must specify -p tcp */
- if (ip->proto != IPPROTO_TCP || (ip->invflags & XT_INV_PROTO)) {
- printk("tcpmss: Only works on TCP packets\n");
- return 0;
- }
-
- return 1;
-}
-
-static struct xt_match tcpmss_match = {
- .name = "tcpmss",
- .match = &match,
- .checkentry = &checkentry,
- .me = THIS_MODULE,
+static struct xt_match xt_tcpmss_match[] = {
+ {
+ .name = "tcpmss",
+ .family = AF_INET,
+ .match = match,
+ .matchsize = sizeof(struct xt_tcpmss_match_info),
+ .proto = IPPROTO_TCP,
+ .me = THIS_MODULE,
+ },
+ {
+ .name = "tcpmss",
+ .family = AF_INET6,
+ .match = match,
+ .matchsize = sizeof(struct xt_tcpmss_match_info),
+ .proto = IPPROTO_TCP,
+ .me = THIS_MODULE,
+ },
};
-static struct xt_match tcpmss6_match = {
- .name = "tcpmss",
- .match = &match,
- .checkentry = &checkentry6,
- .me = THIS_MODULE,
-};
-
-
-static int __init init(void)
+static int __init xt_tcpmss_init(void)
{
- int ret;
- ret = xt_register_match(AF_INET, &tcpmss_match);
- if (ret)
- return ret;
-
- ret = xt_register_match(AF_INET6, &tcpmss6_match);
- if (ret)
- xt_unregister_match(AF_INET, &tcpmss_match);
-
- return ret;
+ return xt_register_matches(xt_tcpmss_match,
+ ARRAY_SIZE(xt_tcpmss_match));
}
-static void __exit fini(void)
+static void __exit xt_tcpmss_fini(void)
{
- xt_unregister_match(AF_INET6, &tcpmss6_match);
- xt_unregister_match(AF_INET, &tcpmss_match);
+ xt_unregister_matches(xt_tcpmss_match, ARRAY_SIZE(xt_tcpmss_match));
}
-module_init(init);
-module_exit(fini);
+module_init(xt_tcpmss_init);
+module_exit(xt_tcpmss_fini);