[NETFILTER]: Add string match

Signed-off-by: Pablo Neira Ayuso <pablo@eurodev.net>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netfilter_ipv4/ipt_string.h b/include/linux/netfilter_ipv4/ipt_string.h
new file mode 100644 (file)
index 0000000..a265f6e
--- /dev/null
+++ b/include/linux/netfilter_ipv4/ipt_string.h
@@ -0,0 +1,18 @@
+#ifndef _IPT_STRING_H
+#define _IPT_STRING_H
+
+#define IPT_STRING_MAX_PATTERN_SIZE 128
+#define IPT_STRING_MAX_ALGO_NAME_SIZE 16
+
+struct ipt_string_info
+{
+       u_int16_t from_offset;
+       u_int16_t to_offset;
+       char      algo[IPT_STRING_MAX_ALGO_NAME_SIZE];
+       char      pattern[IPT_STRING_MAX_PATTERN_SIZE];
+       u_int8_t  patlen;
+       u_int8_t  invert;
+       struct ts_config __attribute__((aligned(8))) *config;
+};
+
+#endif /*_IPT_STRING_H*/

diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 3f7e6e4..f2bea6e 100644 (file)
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -410,6 +410,18 @@ config IP_NF_MATCH_HASHLIMIT
          destination IP' or `500pps from any given source IP'  with a single
          IPtables rule.
 
+config IP_NF_MATCH_STRING
+       tristate  'string match support'
+       depends on IP_NF_IPTABLES 
+       select TEXTSEARCH
+       select TEXTSEARCH_KMP
+       select TEXTSEARCH_FSM
+       help
+         This option adds a `string' match, which allows you to look for
+         pattern matchings in packets.
+
+         To compile it as a module, choose M here.  If unsure, say N.
+
 # `filter', generic and specific targets
 config IP_NF_FILTER
        tristate "Packet filtering"

diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
index 7c8ae85..89cae69 100644 (file)
--- a/net/ipv4/netfilter/Makefile
+++ b/net/ipv4/netfilter/Makefile
@@ -65,6 +65,7 @@ obj-$(CONFIG_IP_NF_MATCH_REALM) += ipt_realm.o
 obj-$(CONFIG_IP_NF_MATCH_ADDRTYPE) += ipt_addrtype.o
 obj-$(CONFIG_IP_NF_MATCH_PHYSDEV) += ipt_physdev.o
 obj-$(CONFIG_IP_NF_MATCH_COMMENT) += ipt_comment.o
+obj-$(CONFIG_IP_NF_MATCH_STRING) += ipt_string.o
 
 # targets
 obj-$(CONFIG_IP_NF_TARGET_REJECT) += ipt_REJECT.o

diff --git a/net/ipv4/netfilter/ipt_string.c b/net/ipv4/netfilter/ipt_string.c
new file mode 100644 (file)
index 0000000..b5def20
--- /dev/null
+++ b/net/ipv4/netfilter/ipt_string.c
@@ -0,0 +1,91 @@
+/* String matching match for iptables
+ * 
+ * (C) 2005 Pablo Neira Ayuso <pablo@eurodev.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/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_string.h>
+#include <linux/textsearch.h>
+
+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");
+MODULE_DESCRIPTION("IP tables string match module");
+MODULE_LICENSE("GPL");
+
+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)
+{
+       struct ts_state state;
+       struct ipt_string_info *conf = (struct ipt_string_info *) matchinfo;
+
+       memset(&state, 0, sizeof(struct ts_state));
+
+       return (skb_find_text((struct sk_buff *)skb, conf->from_offset, 
+                            conf->to_offset, conf->config, &state) 
+                            != UINT_MAX) && !conf->invert;
+}
+
+#define STRING_TEXT_PRIV(m) ((struct ipt_string_info *) m)
+
+static int checkentry(const char *tablename,
+                     const struct ipt_ip *ip,
+                     void *matchinfo,
+                     unsigned int matchsize,
+                     unsigned int hook_mask)
+{
+       struct ipt_string_info *conf = matchinfo;
+       struct ts_config *ts_conf;
+
+       if (matchsize != IPT_ALIGN(sizeof(struct ipt_string_info)))
+               return 0;
+
+       /* Damn, can't handle this case properly with iptables... */
+       if (conf->from_offset > conf->to_offset)
+               return 0;
+
+       ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
+                                    GFP_KERNEL, TS_AUTOLOAD);
+       if (IS_ERR(ts_conf))
+               return 0;
+
+       conf->config = ts_conf;
+
+       return 1;
+}
+
+static void destroy(void *matchinfo, unsigned int matchsize)
+{
+       textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
+}
+
+static struct ipt_match string_match = {
+       .name           = "string",
+       .match          = match,
+       .checkentry     = checkentry,
+       .destroy        = destroy,
+       .me             = THIS_MODULE
+};
+
+static int __init init(void)
+{
+       return ipt_register_match(&string_match);
+}
+
+static void __exit fini(void)
+{
+       ipt_unregister_match(&string_match);
+}
+
+module_init(init);
+module_exit(fini);