The cmp ematch compares a static value provided by userspace against
a 8, 16, or 32bit chunk read from the packet. The reading offset is
provided by userspace and based on one of the skb layers (mac|nh|h).
The ematch provides functionality to transform the byte order of
the chunk and/or apply a mask and understands the operands eq, lt,
and gt. Basically, it is very similiar to the u32 (e)match but tries
filling the gaps left behind.
Signed-off-by: Thomas Graf <tgraf@xxxxxxx>
diff -Nru linux-2.6.11-rc2-bk1.orig/include/linux/pkt_cls.h
linux-2.6.11-rc2-bk1/include/linux/pkt_cls.h
--- linux-2.6.11-rc2-bk1.orig/include/linux/pkt_cls.h 2005-01-23
17:29:35.000000000 +0100
+++ linux-2.6.11-rc2-bk1/include/linux/pkt_cls.h 2005-01-23
17:29:40.000000000 +0100
@@ -383,6 +383,7 @@
enum
{
TCF_EM_CONTAINER,
+ TCF_EM_CMP,
__TCF_EM_MAX
};
@@ -391,4 +392,11 @@
TCF_EM_PROG_TC
};
+enum
+{
+ TCF_EM_OPND_EQ,
+ TCF_EM_OPND_GT,
+ TCF_EM_OPND_LT
+};
+
#endif
diff -Nru linux-2.6.11-rc2-bk1.orig/include/linux/tc_ematch/tc_em_cmp.h
linux-2.6.11-rc2-bk1/include/linux/tc_ematch/tc_em_cmp.h
--- linux-2.6.11-rc2-bk1.orig/include/linux/tc_ematch/tc_em_cmp.h
1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.11-rc2-bk1/include/linux/tc_ematch/tc_em_cmp.h 2005-01-23
17:29:40.000000000 +0100
@@ -0,0 +1,26 @@
+#ifndef __LINUX_TC_EM_CMP_H
+#define __LINUX_TC_EM_CMP_H
+
+#include <linux/pkt_cls.h>
+
+struct tcf_em_cmp
+{
+ __u32 val;
+ __u32 mask;
+ __u16 off;
+ __u8 align:4;
+ __u8 flags:4;
+ __u8 layer:4;
+ __u8 opnd:4;
+};
+
+enum
+{
+ TCF_EM_ALIGN_U8 = 1,
+ TCF_EM_ALIGN_U16 = 2,
+ TCF_EM_ALIGN_U32 = 4
+};
+
+#define TCF_EM_CMP_TRANS 1
+
+#endif
diff -Nru linux-2.6.11-rc2-bk1.orig/include/net/pkt_cls.h
linux-2.6.11-rc2-bk1/include/net/pkt_cls.h
--- linux-2.6.11-rc2-bk1.orig/include/net/pkt_cls.h 2005-01-23
17:29:35.000000000 +0100
+++ linux-2.6.11-rc2-bk1/include/net/pkt_cls.h 2005-01-23 17:30:55.000000000
+0100
@@ -318,6 +318,26 @@
#endif /* CONFIG_NET_EMATCH */
+static inline unsigned char * tcf_get_base_ptr(struct sk_buff *skb, int layer)
+{
+ switch (layer) {
+ case TCF_LAYER_LINK:
+ return skb->data;
+ case TCF_LAYER_NETWORK:
+ return skb->nh.raw;
+ case TCF_LAYER_TRANSPORT:
+ return skb->h.raw;
+ }
+
+ return NULL;
+}
+
+static inline int tcf_valid_offset(struct sk_buff *skb, unsigned char *ptr,
+ int len)
+{
+ return unlikely((ptr + len) < skb->tail && ptr > skb->head);
+}
+
#ifdef CONFIG_NET_CLS_IND
static inline int
tcf_change_indev(struct tcf_proto *tp, char *indev, struct rtattr *indev_tlv)
diff -Nru linux-2.6.11-rc2-bk1.orig/net/sched/Kconfig
linux-2.6.11-rc2-bk1/net/sched/Kconfig
--- linux-2.6.11-rc2-bk1.orig/net/sched/Kconfig 2005-01-23 17:29:35.000000000
+0100
+++ linux-2.6.11-rc2-bk1/net/sched/Kconfig 2005-01-23 17:29:40.000000000
+0100
@@ -398,6 +398,16 @@
encapsulated precedences. Every level requires 4 bytes of addtional
stack space.
+config NET_EMATCH_CMP
+ tristate "Simple packet data comparison"
+ depends on NET_EMATCH
+ ---help---
+ Say Y here if you want to be able to classify packets based on
+ simple packet data comparisons for 8, 16, and 32bit values.
+
+ To compile this code as a module, choose M here: the
+ module will be called em_cmp.
+
config NET_CLS_ACT
bool "Packet ACTION"
depends on EXPERIMENTAL && NET_CLS && NET_QOS
diff -Nru linux-2.6.11-rc2-bk1.orig/net/sched/Makefile
linux-2.6.11-rc2-bk1/net/sched/Makefile
--- linux-2.6.11-rc2-bk1.orig/net/sched/Makefile 2005-01-23
17:29:35.000000000 +0100
+++ linux-2.6.11-rc2-bk1/net/sched/Makefile 2005-01-23 17:29:40.000000000
+0100
@@ -34,3 +34,4 @@
obj-$(CONFIG_NET_CLS_TCINDEX) += cls_tcindex.o
obj-$(CONFIG_NET_CLS_RSVP6) += cls_rsvp6.o
obj-$(CONFIG_NET_EMATCH) += ematch.o
+obj-$(CONFIG_NET_EMATCH_CMP) += em_cmp.o
diff -Nru linux-2.6.11-rc2-bk1.orig/net/sched/em_cmp.c
linux-2.6.11-rc2-bk1/net/sched/em_cmp.c
--- linux-2.6.11-rc2-bk1.orig/net/sched/em_cmp.c 1970-01-01
01:00:00.000000000 +0100
+++ linux-2.6.11-rc2-bk1/net/sched/em_cmp.c 2005-01-23 17:31:03.000000000
+0100
@@ -0,0 +1,101 @@
+/*
+ * net/sched/em_cmp.c Simple packet data comparison 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 <tgraf@xxxxxxx>
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/tc_ematch/tc_em_cmp.h>
+#include <net/pkt_cls.h>
+
+static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp)
+{
+ return unlikely(cmp->flags & TCF_EM_CMP_TRANS);
+}
+
+static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em,
+ struct tcf_pkt_info *info)
+{
+ struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data;
+ unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off;
+ u32 val = 0;
+
+ if (!tcf_valid_offset(skb, ptr, cmp->align))
+ return 0;
+
+ switch (cmp->align) {
+ case TCF_EM_ALIGN_U8:
+ val = *ptr;
+ break;
+
+ case TCF_EM_ALIGN_U16:
+ val = *ptr << 8;
+ val |= *(ptr+1);
+
+ if (cmp_needs_transformation(cmp))
+ val = be16_to_cpu(val);
+ break;
+
+ case TCF_EM_ALIGN_U32:
+ /* Worth checking boundries? The branching seems
+ * to get worse. Visit again. */
+ val = *ptr << 24;
+ val |= *(ptr+1) << 16;
+ val |= *(ptr+2) << 8;
+ val |= *(ptr+3);
+
+ if (cmp_needs_transformation(cmp))
+ val = be32_to_cpu(val);
+ break;
+
+ default:
+ return 0;
+ }
+
+ if (cmp->mask)
+ val &= cmp->mask;
+
+ switch (cmp->opnd) {
+ case TCF_EM_OPND_EQ:
+ return val == cmp->val;
+ case TCF_EM_OPND_LT:
+ return val < cmp->val;
+ case TCF_EM_OPND_GT:
+ return val > cmp->val;
+ }
+
+ return 0;
+}
+
+static struct tcf_ematch_ops em_cmp_ops = {
+ .kind = TCF_EM_CMP,
+ .datalen = sizeof(struct tcf_em_cmp),
+ .match = em_cmp_match,
+ .owner = THIS_MODULE,
+ .link = LIST_HEAD_INIT(em_cmp_ops.link)
+};
+
+static int __init init_em_cmp(void)
+{
+ return tcf_em_register(&em_cmp_ops);
+}
+
+static void __exit exit_em_cmp(void)
+{
+ tcf_em_unregister(&em_cmp_ops);
+}
+
+MODULE_LICENSE("GPL");
+
+module_init(init_em_cmp);
+module_exit(exit_em_cmp);
+
|