[PKT_SCHED]: Packet classification based on textsearch (ematch)

Signed-off-by: Thomas Graf <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/pkt_cls.h

···
 	TCF_EM_NBYTE,
 	TCF_EM_U32,
 	TCF_EM_META,
+	TCF_EM_TEXT,
 	__TCF_EM_MAX
 };
 

include/linux/rtnetlink.h

···
 		 goto rtattr_failure; \
    	__rta_fill(skb, attrtype, attrlen, data); }) 
 
-#define RTA_PUT_NOHDR(skb, attrlen, data) \
+#define RTA_APPEND(skb, attrlen, data) \
 ({	if (unlikely(skb_tailroom(skb) < (int)(attrlen))) \
 		goto rtattr_failure; \
-	memcpy(skb_put(skb, RTA_ALIGN(attrlen)), data, attrlen); })
+	memcpy(skb_put(skb, attrlen), data, attrlen); })
+
+#define RTA_PUT_NOHDR(skb, attrlen, data) \
+	RTA_APPEND(skb, RTA_ALIGN(attrlen), data)
 
 #define RTA_PUT_U8(skb, attrtype, value) \
 ({	u8 _tmp = (value); \

include/linux/tc_ematch/tc_em_text.h

···
+#ifndef __LINUX_TC_EM_TEXT_H
+#define __LINUX_TC_EM_TEXT_H
+
+#include <linux/pkt_cls.h>
+
+#define TC_EM_TEXT_ALGOSIZ	16
+
+struct tcf_em_text
+{
+	char		algo[TC_EM_TEXT_ALGOSIZ];
+	__u16		from_offset;
+	__u16		to_offset;
+	__u16		pattern_len;
+	__u8		from_layer:4;
+	__u8		to_layer:4;
+	__u8		pad;
+};
+
+#endif

net/sched/Kconfig

···
 	  To compile this code as a module, choose M here: the
 	  module will be called em_meta.
 
+config NET_EMATCH_TEXT
+	tristate "Textsearch"
+	depends on NET_EMATCH
+	---help---
+	  Say Y here if you want to be ablt to classify packets based on
+	  textsearch comparisons. Please select the appropriate textsearch
+	  algorithms in the Library section.
+
+	  To compile this code as a module, choose M here: the
+	  module will be called em_text.
+
 config NET_CLS_ACT
 	bool "Packet ACTION"
 	depends on EXPERIMENTAL && NET_CLS && NET_QOS

net/sched/Makefile

···
 obj-$(CONFIG_NET_EMATCH_NBYTE)	+= em_nbyte.o
 obj-$(CONFIG_NET_EMATCH_U32)	+= em_u32.o
 obj-$(CONFIG_NET_EMATCH_META)	+= em_meta.o
+obj-$(CONFIG_NET_EMATCH_TEXT)	+= em_text.o

net/sched/em_text.c

···
+/*
+ * net/sched/em_text.c	Textsearch ematch
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ *
+ * Authors:	Thomas Graf <[e-mail]>
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/skbuff.h>
+#include <linux/textsearch.h>
+#include <linux/tc_ematch/tc_em_text.h>
+#include <net/pkt_cls.h>
+
+struct text_match
+{
+	u16			from_offset;
+	u16			to_offset;
+	u8			from_layer;
+	u8			to_layer;
+	struct ts_config	*config;
+};
+
+#define EM_TEXT_PRIV(m) ((struct text_match *) (m)->data)
+
+static int em_text_match(struct sk_buff *skb, struct tcf_ematch *m,
+			 struct tcf_pkt_info *info)
+{
+	struct text_match *tm = EM_TEXT_PRIV(m);
+	int from, to;
+	struct ts_state state;
+
+	from = tcf_get_base_ptr(skb, tm->from_layer) - skb->data;
+	from += tm->from_offset;
+
+	to = tcf_get_base_ptr(skb, tm->to_layer) - skb->data;
+	to += tm->to_offset;
+
+	return skb_find_text(skb, from, to, tm->config, &state) != UINT_MAX;
+}
+
+static int em_text_change(struct tcf_proto *tp, void *data, int len,
+			  struct tcf_ematch *m)
+{
+	struct text_match *tm;
+	struct tcf_em_text *conf = data;
+	struct ts_config *ts_conf;
+	int flags = 0;
+
+	printk("Configuring text: %s from %d:%d to %d:%d len %d\n", conf->algo, conf->from_offset,
+	    conf->from_layer, conf->to_offset, conf->to_layer, conf->pattern_len);
+
+	if (len < sizeof(*conf) || len < (sizeof(*conf) + conf->pattern_len))
+		return -EINVAL;
+
+	if (conf->from_layer > conf->to_layer)
+		return -EINVAL;
+
+	if (conf->from_layer == conf->to_layer &&
+	    conf->from_offset > conf->to_offset)
+		return -EINVAL;
+
+retry:
+	ts_conf = textsearch_prepare(conf->algo, (u8 *) conf + sizeof(*conf),
+				     conf->pattern_len, GFP_KERNEL, flags);
+
+	if (flags & TS_AUTOLOAD)
+		rtnl_lock();
+
+	if (IS_ERR(ts_conf)) {
+		if (PTR_ERR(ts_conf) == -ENOENT && !(flags & TS_AUTOLOAD)) {
+			rtnl_unlock();
+			flags |= TS_AUTOLOAD;
+			goto retry;
+		} else
+			return PTR_ERR(ts_conf);
+	} else if (flags & TS_AUTOLOAD) {
+		textsearch_destroy(ts_conf);
+		return -EAGAIN;
+	}
+
+	tm = kmalloc(sizeof(*tm), GFP_KERNEL);
+	if (tm == NULL) {
+		textsearch_destroy(ts_conf);
+		return -ENOBUFS;
+	}
+
+	tm->from_offset = conf->from_offset;
+	tm->to_offset   = conf->to_offset;
+	tm->from_layer  = conf->from_layer;
+	tm->to_layer    = conf->to_layer;
+	tm->config      = ts_conf;
+
+	m->datalen = sizeof(*tm);
+	m->data = (unsigned long) tm;
+
+	return 0;
+}
+
+static void em_text_destroy(struct tcf_proto *tp, struct tcf_ematch *m)
+{
+	textsearch_destroy(EM_TEXT_PRIV(m)->config);
+}
+
+static int em_text_dump(struct sk_buff *skb, struct tcf_ematch *m)
+{
+	struct text_match *tm = EM_TEXT_PRIV(m);
+	struct tcf_em_text conf;
+
+	strncpy(conf.algo, tm->config->ops->name, sizeof(conf.algo) - 1);
+	conf.from_offset = tm->from_offset;
+	conf.to_offset = tm->to_offset;
+	conf.from_layer = tm->from_layer;
+	conf.to_layer = tm->to_layer;
+	conf.pattern_len = textsearch_get_pattern_len(tm->config);
+	conf.pad = 0;
+
+	RTA_PUT_NOHDR(skb, sizeof(conf), &conf);
+	RTA_APPEND(skb, conf.pattern_len, textsearch_get_pattern(tm->config));
+	return 0;
+
+rtattr_failure:
+	return -1;
+}		
+
+static struct tcf_ematch_ops em_text_ops = {
+	.kind	  = TCF_EM_TEXT,
+	.change	  = em_text_change,
+	.match	  = em_text_match,
+	.destroy  = em_text_destroy,
+	.dump	  = em_text_dump,
+	.owner	  = THIS_MODULE,
+	.link	  = LIST_HEAD_INIT(em_text_ops.link)
+};
+
+static int __init init_em_text(void)
+{
+	return tcf_em_register(&em_text_ops);
+}
+
+static void __exit exit_em_text(void) 
+{
+	tcf_em_unregister(&em_text_ops);
+}
+
+MODULE_LICENSE("GPL");
+
+module_init(init_em_text);
+module_exit(exit_em_text);