[RFC, NETFILTER]: amanda helper: convert to textsearch infrastructure

[Patrick McHardy <kaber@trash.net>]

[-- Attachment #1: Type: text/plain, Size: 296 bytes --]

I've just converted the amanda helper to the textsearch infrastructure
to fix a packet corruption bug. This allows to avoid the data copying
and save roughly 64k of memory. The IRC helper looks like a good
candidate for this too, FTP is probably quite a bit more complicated.

Comments welcome.


[-- Attachment #2: x --]
[-- Type: text/plain, Size: 6917 bytes --]

[NETFILTER]: amanda helper: convert to textsearch infrastructure

When a port number within a packet is replaced by a differently sized
number only the packet is resized, but not the copy of the data.
Following port numbers are rewritten based on their offsets within
the copy, leading to packet corruption.

Convert the amanda helper to the textsearch infrastructure to avoid
the copy entirely.

Signed-off-by: Patrick McHardy <kaber@trash.net>

---
commit 23b9a4b7fd6c16efd069b1b4de6e605fdc56634c
tree 0145077411b1866778a745d14805baaa7d5f290f
parent a54c9d30dbb06391ec4422aaf0e1dc2c8c53bd3e
author Patrick McHardy <kaber@trash.net> Fri, 19 May 2006 18:30:54 +0200
committer Patrick McHardy <kaber@trash.net> Fri, 19 May 2006 18:30:54 +0200

 net/ipv4/netfilter/Kconfig               |    2 
 net/ipv4/netfilter/ip_conntrack_amanda.c |  140 ++++++++++++++++++++----------
 2 files changed, 93 insertions(+), 49 deletions(-)

diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 3d560de..d859754 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -142,6 +142,8 @@ config IP_NF_TFTP
 config IP_NF_AMANDA
 	tristate "Amanda backup protocol support"
 	depends on IP_NF_CONNTRACK
+	select TEXTSEARCH
+	select TEXTSEARCH_KMP
 	help
 	  If you are running the Amanda backup package <http://www.amanda.org/>
 	  on this machine or machines that will be MASQUERADED through this
diff --git a/net/ipv4/netfilter/ip_conntrack_amanda.c b/net/ipv4/netfilter/ip_conntrack_amanda.c
index a604b1c..34b2309 100644
--- a/net/ipv4/netfilter/ip_conntrack_amanda.c
+++ b/net/ipv4/netfilter/ip_conntrack_amanda.c
@@ -17,17 +17,16 @@
  *	this value.
  *
  */
-
-#include <linux/in.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/netfilter.h>
-#include <linux/ip.h>
 #include <linux/moduleparam.h>
+#include <linux/textsearch.h>
+#include <linux/skbuff.h>
+#include <linux/in.h>
+#include <linux/ip.h>
 #include <linux/udp.h>
-#include <net/checksum.h>
-#include <net/udp.h>
 
+#include <linux/netfilter.h>
 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
 #include <linux/netfilter_ipv4/ip_conntrack_amanda.h>
 
@@ -39,12 +38,6 @@ MODULE_LICENSE("GPL");
 module_param(master_timeout, uint, 0600);
 MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
 
-static const char *conns[] = { "DATA ", "MESG ", "INDEX " };
-
-/* This is slow, but it's simple. --RR */
-static char *amanda_buffer;
-static DEFINE_SPINLOCK(amanda_buffer_lock);
-
 unsigned int (*ip_nat_amanda_hook)(struct sk_buff **pskb,
 				   enum ip_conntrack_info ctinfo,
 				   unsigned int matchoff,
@@ -52,12 +45,48 @@ unsigned int (*ip_nat_amanda_hook)(struc
 				   struct ip_conntrack_expect *exp);
 EXPORT_SYMBOL_GPL(ip_nat_amanda_hook);
 
+enum amanda_strings {
+	SEARCH_CONNECT,
+	SEARCH_NEWLINE,
+	SEARCH_DATA,
+	SEARCH_MESG,
+	SEARCH_INDEX,
+};
+
+static struct {
+	char			*string;
+	size_t			len;
+	struct ts_config	*ts;
+} search[] = {
+	[SEARCH_CONNECT] = {
+		.string	= "CONNECT ",
+		.len	= 8,
+	},
+	[SEARCH_NEWLINE] = {
+		.string	= "\n",
+		.len	= 1,
+	},
+	[SEARCH_DATA] = {
+		.string	= "DATA ",
+		.len	= 5,
+	},
+	[SEARCH_MESG] = {
+		.string	= "MESG ",
+		.len	= 5,
+	},
+	[SEARCH_INDEX] = {
+		.string = "INDEX ",
+		.len	= 6,
+	},
+};
+
 static int help(struct sk_buff **pskb,
                 struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
 {
+	struct ts_state ts;
 	struct ip_conntrack_expect *exp;
-	char *data, *data_limit, *tmp;
-	unsigned int dataoff, i;
+	unsigned int dataoff, start, stop, off, i;
+	char pbuf[sizeof("65535")], *tmp;
 	u_int16_t port, len;
 	int ret = NF_ACCEPT;
 
@@ -77,29 +106,34 @@ static int help(struct sk_buff **pskb,
 		return NF_ACCEPT;
 	}
 
-	spin_lock_bh(&amanda_buffer_lock);
-	skb_copy_bits(*pskb, dataoff, amanda_buffer, (*pskb)->len - dataoff);
-	data = amanda_buffer;
-	data_limit = amanda_buffer + (*pskb)->len - dataoff;
-	*data_limit = '\0';
-
-	/* Search for the CONNECT string */
-	data = strstr(data, "CONNECT ");
-	if (!data)
+	memset(&ts, 0, sizeof(ts));
+	start = skb_find_text(*pskb, dataoff, (*pskb)->len,
+			      search[SEARCH_CONNECT].ts, &ts);
+	if (start == UINT_MAX)
 		goto out;
-	data += strlen("CONNECT ");
+	start += dataoff + search[SEARCH_CONNECT].len;
 
-	/* Only search first line. */	
-	if ((tmp = strchr(data, '\n')))
-		*tmp = '\0';
+	memset(&ts, 0, sizeof(ts));
+	stop = skb_find_text(*pskb, start, (*pskb)->len,
+			     search[SEARCH_NEWLINE].ts, &ts);
+	if (stop == UINT_MAX)
+		goto out;
+	stop += start;
 
-	for (i = 0; i < ARRAY_SIZE(conns); i++) {
-		char *match = strstr(data, conns[i]);
-		if (!match)
+	for (i = SEARCH_DATA; i <= SEARCH_INDEX; i++) {
+		memset(&ts, 0, sizeof(ts));
+		off = skb_find_text(*pskb, start, stop, search[i].ts, &ts);
+		if (off == UINT_MAX)
 			continue;
-		tmp = data = match + strlen(conns[i]);
-		port = simple_strtoul(data, &data, 10);
-		len = data - tmp;
+		off += start + search[i].len;
+
+		len = min_t(unsigned int, sizeof(pbuf) - 1, stop - off);
+		if (skb_copy_bits(*pskb, off, pbuf, len))
+			break;
+		pbuf[len] = '\0';
+
+		port = simple_strtoul(pbuf, &tmp, 10);
+		len = tmp - pbuf;
 		if (port == 0 || len > 5)
 			break;
 
@@ -125,8 +159,7 @@ static int help(struct sk_buff **pskb,
 		exp->mask.dst.u.tcp.port = 0xFFFF;
 
 		if (ip_nat_amanda_hook)
-			ret = ip_nat_amanda_hook(pskb, ctinfo,
-						 tmp - amanda_buffer,
+			ret = ip_nat_amanda_hook(pskb, ctinfo, off - dataoff,
 						 len, exp);
 		else if (ip_conntrack_expect_related(exp) != 0)
 			ret = NF_DROP;
@@ -134,12 +167,11 @@ static int help(struct sk_buff **pskb,
 	}
 
 out:
-	spin_unlock_bh(&amanda_buffer_lock);
 	return ret;
 }
 
 static struct ip_conntrack_helper amanda_helper = {
-	.max_expected = ARRAY_SIZE(conns),
+	.max_expected = 3,
 	.timeout = 180,
 	.me = THIS_MODULE,
 	.help = help,
@@ -155,26 +187,36 @@ static struct ip_conntrack_helper amanda
 
 static void __exit ip_conntrack_amanda_fini(void)
 {
+	int i;
+
 	ip_conntrack_helper_unregister(&amanda_helper);
-	kfree(amanda_buffer);
+	for (i = 0; i < ARRAY_SIZE(search); i++)
+		textsearch_destroy(search[i].ts);
 }
 
 static int __init ip_conntrack_amanda_init(void)
 {
-	int ret;
-
-	amanda_buffer = kmalloc(65536, GFP_KERNEL);
-	if (!amanda_buffer)
-		return -ENOMEM;
-
-	ret = ip_conntrack_helper_register(&amanda_helper);
-	if (ret < 0) {
-		kfree(amanda_buffer);
-		return ret;
+	int ret, i;
+
+	ret = -ENOMEM;
+	for (i = 0; i < ARRAY_SIZE(search); i++) {
+		search[i].ts = textsearch_prepare("kmp", search[i].string,
+						  search[i].len,
+						  GFP_KERNEL, TS_AUTOLOAD);
+		if (search[i].ts == NULL)
+			goto err;
 	}
+	ret = ip_conntrack_helper_register(&amanda_helper);
+	if (ret < 0)
+		goto err;
 	return 0;
 
-
+err:
+	for (; i >= 0; i--) {
+		if (search[i].ts)
+			textsearch_destroy(search[i].ts);
+	}
+	return ret;
 }
 
 module_init(ip_conntrack_amanda_init);