- added description of djurban's branch

[packages/kernel.git] / 2.6.1-rc1-NF-u32-20040105.patch

diff -Nur linux-2.6.1-rc1.org/include/linux/netfilter_ipv4/ipt_u32.h linux-2.6.1-rc1/include/linux/netfilter_ipv4/ipt_u32.h
--- linux-2.6.1-rc1.org/include/linux/netfilter_ipv4/ipt_u32.h  1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.1-rc1/include/linux/netfilter_ipv4/ipt_u32.h      2004-01-05 11:29:48.000000000 +0100
@@ -0,0 +1,40 @@
+#ifndef _IPT_U32_H
+#define _IPT_U32_H
+#include <linux/netfilter_ipv4/ip_tables.h>
+
+enum ipt_u32_ops
+{
+       IPT_U32_AND,
+       IPT_U32_LEFTSH,
+       IPT_U32_RIGHTSH,
+       IPT_U32_AT
+};
+
+struct ipt_u32_location_element
+{
+       u_int32_t number;
+       u_int8_t nextop;
+};
+struct ipt_u32_value_element
+{
+       u_int32_t min;
+       u_int32_t max;
+};
+/* *** any way to allow for an arbitrary number of elements?
+   for now I settle for a limit of 10 of each */
+#define U32MAXSIZE 10
+struct ipt_u32_test
+{
+       u_int8_t nnums;
+       struct ipt_u32_location_element location[U32MAXSIZE+1];
+       u_int8_t nvalues;
+       struct ipt_u32_value_element value[U32MAXSIZE+1];
+};
+
+struct ipt_u32
+{
+       u_int8_t ntests;
+       struct ipt_u32_test tests[U32MAXSIZE+1];
+};
+
+#endif /*_IPT_U32_H*/
diff -Nur linux-2.6.1-rc1.org/net/ipv4/netfilter/Kconfig linux-2.6.1-rc1/net/ipv4/netfilter/Kconfig
--- linux-2.6.1-rc1.org/net/ipv4/netfilter/Kconfig      2004-01-05 11:35:02.000000000 +0100
+++ linux-2.6.1-rc1/net/ipv4/netfilter/Kconfig  2004-01-05 11:29:48.000000000 +0100
@@ -596,5 +596,18 @@
            will match the packets (locally generated) that have a departure timestamp
            in the range 8:00->18:00 on Monday only.
 
+config IP_NF_MATCH_U32
+       tristate  'U32 match support'
+       depends on IP_NF_IPTABLES
+         help
+         
+         U32 allows you to extract quantities of up to 4 bytes from a packet,
+         AND them with specified masks, shift them by specified amounts and
+         test whether the results are in any of a set of specified ranges.
+         The specification of what to extract is general enough to skip over
+         headers with lengths stored in the packet, as in IP or TCP header
+         lengths.
+         Details and examples are in the kernel module source.
+
 endmenu
 
diff -Nur linux-2.6.1-rc1.org/net/ipv4/netfilter/Makefile linux-2.6.1-rc1/net/ipv4/netfilter/Makefile
--- linux-2.6.1-rc1.org/net/ipv4/netfilter/Makefile     2004-01-05 11:35:02.000000000 +0100
+++ linux-2.6.1-rc1/net/ipv4/netfilter/Makefile 2004-01-05 11:29:48.000000000 +0100
@@ -62,6 +62,9 @@
 
 obj-$(CONFIG_IP_NF_MATCH_LENGTH) += ipt_length.o
 
+obj-$(CONFIG_IP_NF_MATCH_U32) += ipt_u32.o
+
+
 obj-$(CONFIG_IP_NF_MATCH_TTL) += ipt_ttl.o
 obj-$(CONFIG_IP_NF_MATCH_STATE) += ipt_state.o
 obj-$(CONFIG_IP_NF_MATCH_CONNTRACK) += ipt_conntrack.o
diff -Nur linux-2.6.1-rc1.org/net/ipv4/netfilter/ipt_u32.c linux-2.6.1-rc1/net/ipv4/netfilter/ipt_u32.c
--- linux-2.6.1-rc1.org/net/ipv4/netfilter/ipt_u32.c    1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.1-rc1/net/ipv4/netfilter/ipt_u32.c        2004-01-05 11:29:48.000000000 +0100
@@ -0,0 +1,211 @@
+/* Kernel module to match u32 packet content. */
+
+/* 
+U32 tests whether quantities of up to 4 bytes extracted from a packet 
+have specified values.  The specification of what to extract is general 
+enough to find data at given offsets from tcp headers or payloads.
+
+ --u32 tests
+ The argument amounts to a program in a small language described below.
+ tests := location = value |  tests && location = value
+ value := range | value , range
+ range := number | number : number
+  a single number, n, is interpreted the same as n:n
+  n:m is interpreted as the range of numbers >=n and <=m
+ location := number | location operator number
+ operator := & | << | >> | @
+
+ The operators &, <<, >>, && mean the same as in c.  The = is really a set
+ membership operator and the value syntax describes a set.  The @ operator
+ is what allows moving to the next header and is described further below.
+
+ *** Until I can find out how to avoid it, there are some artificial limits
+ on the size of the tests:
+ - no more than 10 ='s (and 9 &&'s) in the u32 argument
+ - no more than 10 ranges (and 9 commas) per value
+ - no more than 10 numbers (and 9 operators) per location
+
+ To describe the meaning of location, imagine the following machine that
+ interprets it.  There are three registers:
+  A is of type char*, initially the address of the IP header
+  B and C are unsigned 32 bit integers, initially zero
+
+  The instructions are:
+   number      B = number;
+               C = (*(A+B)<<24)+(*(A+B+1)<<16)+(*(A+B+2)<<8)+*(A+B+3)
+   &number     C = C&number
+   <<number    C = C<<number
+   >>number    C = C>>number
+   @number     A = A+C; then do the instruction number
+  Any access of memory outside [skb->head,skb->end] causes the match to fail.
+  Otherwise the result of the computation is the final value of C.
+
+ Whitespace is allowed but not required in the tests.
+ However the characters that do occur there are likely to require
+ shell quoting, so it's a good idea to enclose the arguments in quotes.
+
+Example:
+ match IP packets with total length >= 256
+ The IP header contains a total length field in bytes 2-3.
+ --u32 "0&0xFFFF=0x100:0xFFFF" 
+ read bytes 0-3
+ AND that with FFFF (giving bytes 2-3),
+ and test whether that's in the range [0x100:0xFFFF]
+
+Example: (more realistic, hence more complicated)
+ match icmp packets with icmp type 0
+ First test that it's an icmp packet, true iff byte 9 (protocol) = 1
+ --u32 "6&0xFF=1 && ...
+ read bytes 6-9, use & to throw away bytes 6-8 and compare the result to 1
+ Next test that it's not a fragment.
+  (If so it might be part of such a packet but we can't always tell.)
+  n.b. This test is generally needed if you want to match anything
+  beyond the IP header.
+ The last 6 bits of byte 6 and all of byte 7 are 0 iff this is a complete
+ packet (not a fragment).  Alternatively, you can allow first fragments
+ by only testing the last 5 bits of byte 6.
+ ... 4&0x3FFF=0 && ...
+ Last test: the first byte past the IP header (the type) is 0
+ This is where we have to use the @syntax.  The length of the IP header
+ (IHL) in 32 bit words is stored in the right half of byte 0 of the
+ IP header itself.
+ ... 0>>22&0x3C@0>>24=0"
+ The first 0 means read bytes 0-3,
+ >>22 means shift that 22 bits to the right.  Shifting 24 bits would give
+   the first byte, so only 22 bits is four times that plus a few more bits.
+ &3C then eliminates the two extra bits on the right and the first four 
+ bits of the first byte.
+ For instance, if IHL=5 then the IP header is 20 (4 x 5) bytes long.
+ In this case bytes 0-1 are (in binary) xxxx0101 yyzzzzzz, 
+ >>22 gives the 10 bit value xxxx0101yy and &3C gives 010100.
+ @ means to use this number as a new offset into the packet, and read
+ four bytes starting from there.  This is the first 4 bytes of the icmp
+ payload, of which byte 0 is the icmp type.  Therefore we simply shift
+ the value 24 to the right to throw out all but the first byte and compare
+ the result with 0.
+
+Example: 
+ tcp payload bytes 8-12 is any of 1, 2, 5 or 8
+ First we test that the packet is a tcp packet (similar to icmp).
+ --u32 "6&0xFF=6 && ...
+ Next, test that it's not a fragment (same as above).
+ ... 0>>22&0x3C@12>>26&0x3C@8=1,2,5,8"
+ 0>>22&3C as above computes the number of bytes in the IP header.
+ @ makes this the new offset into the packet, which is the start of the
+ tcp header.  The length of the tcp header (again in 32 bit words) is
+ the left half of byte 12 of the tcp header.  The 12>>26&3C
+ computes this length in bytes (similar to the IP header before).
+ @ makes this the new offset, which is the start of the tcp payload.
+ Finally 8 reads bytes 8-12 of the payload and = checks whether the
+ result is any of 1, 2, 5 or 8
+*/
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+
+#include <linux/netfilter_ipv4/ipt_u32.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+
+/* #include <asm-i386/timex.h> for timing */
+
+MODULE_AUTHOR("Don Cohen <don@isis.cs3-inc.com>");
+MODULE_DESCRIPTION("IP tables u32 matching 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,
+      const void *hdr,
+      u_int16_t datalen,
+      int *hotdrop)
+{
+       const struct ipt_u32 *data = matchinfo;
+       int testind, i;
+       unsigned char* origbase = (char*)skb->nh.iph;
+       unsigned char* base = origbase;
+       unsigned char* head = skb->head;
+       unsigned char* end = skb->end;
+       int nnums, nvals;
+       u_int32_t pos, val;
+       /* unsigned long long cycles1, cycles2, cycles3, cycles4;
+          cycles1 = get_cycles(); */
+
+       for (testind=0; testind < data->ntests; testind++) {
+               base = origbase; /* reset for each test */
+               pos = data->tests[testind].location[0].number;
+               if (base+pos+3 > end || base+pos < head) 
+                       return 0;
+               val = (base[pos]<<24) + (base[pos+1]<<16) +
+                       (base[pos+2]<<8) + base[pos+3];
+               nnums = data->tests[testind].nnums;
+               for (i=1; i < nnums; i++) {
+                       u_int32_t number = data->tests[testind].location[i].number;
+                       switch (data->tests[testind].location[i].nextop) {
+                       case IPT_U32_AND: 
+                               val = val & number; 
+                               break;
+                       case IPT_U32_LEFTSH: 
+                               val = val << number;
+                               break;
+                       case IPT_U32_RIGHTSH: 
+                               val = val >> number; 
+                               break;
+                       case IPT_U32_AT:
+                               base = base + val;
+                               pos = number;
+                               if (base+pos+3 > end || base+pos < head) 
+                                       return 0;
+                               val = (base[pos]<<24) + (base[pos+1]<<16) +
+                                       (base[pos+2]<<8) + base[pos+3];
+                               break;
+                       }
+               }
+               nvals = data->tests[testind].nvalues;
+               for (i=0; i < nvals; i++) {
+                       if ((data->tests[testind].value[i].min <= val) &&
+                           (val <= data->tests[testind].value[i].max)) {
+                               break;
+                       }
+               }
+               if (i >= data->tests[testind].nvalues) {
+                       /* cycles2 = get_cycles(); 
+                          printk("failed %d in %d cycles\n", testind, 
+                                 cycles2-cycles1); */
+                       return 0;
+               }
+       }
+       /* cycles2 = get_cycles();
+          printk("succeeded in %d cycles\n", cycles2-cycles1); */
+       return 1;
+}
+
+static int
+checkentry(const char *tablename,
+           const struct ipt_ip *ip,
+           void *matchinfo,
+           unsigned int matchsize,
+           unsigned int hook_mask)
+{
+       if (matchsize != IPT_ALIGN(sizeof(struct ipt_u32)))
+               return 0;
+       return 1;
+}
+
+static struct ipt_match u32_match
+= { { NULL, NULL }, "u32", &match, &checkentry, NULL, THIS_MODULE };
+
+static int __init init(void)
+{
+       return ipt_register_match(&u32_match);
+}
+
+static void __exit fini(void)
+{
+       ipt_unregister_match(&u32_match);
+}
+
+module_init(init);
+module_exit(fini);