: Fix multiple bugs in dst match

Fix multiple bugs in dst match:

- ".me = THIS_MODULE" is missing
- The cast of the pointer to the next IPv6 extension header is wrong.
- hdrlen may underflow.
- (u16)*optdesc causes to alignment problem.
- The calculation of the offset to next option is wrong. In the case that the type isn't 0, it should be "Opt Data Len" field + 2 (see RFC2460).

# This is a BitKeeper generated diff -Nru style patch. #
# ChangeSet
# 2004/10/25 00:39:13+02:00 [email protected]
# [NETFILTER]: Fix multiple bugs in dst match
#
# This patch fixes the following bugs in ip6t_dst.c.
#

#     - ".me = THIS_MODULE" is missing 
#     - The cast of the pointer to the next IPv6 extension header is wrong.
#     - hdrlen may underflow.
#     - (u16)*optdesc causes to alignment problem.
#     - The calculation of the offset to next option is wrong. In the case

# that the type isn't 0, it should be "Opt Data Len" field + 2
# (see RFC2460).
#
# Signed-off-by: Yasuyuki KOZAKAI <[email protected]>
# Signed-off-by: Patrick McHardy <[email protected]>
#

# net/ipv6/netfilter/ip6t_dst.c
#   2004/10/25 00:39:07+02:00 [email protected] +39 -37
#   [NETFILTER]: Fix multiple bugs in dst match
#   
#   This patch fixes the following bugs in ip6t_dst.c.
#   
#     - ".me = THIS_MODULE" is missing 
#     - The cast of the pointer to the next IPv6 extension header is wrong.
#     - hdrlen may underflow.
#     - (u16)*optdesc causes to alignment problem.
#     - The calculation of the offset to next option is wrong. In the case
#       that the type isn't 0, it should be "Opt Data Len" field + 2
#       (see RFC2460).
#   
#   Signed-off-by: Yasuyuki KOZAKAI <[email protected]>
#   Signed-off-by: Patrick McHardy <[email protected]>
# 
diff -Nru a/net/ipv6/netfilter/ip6t_dst.c b/net/ipv6/netfilter/ip6t_dst.c
--- a/net/ipv6/netfilter/ip6t_dst.c	2004-10-25 01:13:48 +02:00
+++ b/net/ipv6/netfilter/ip6t_dst.c	2004-10-25 01:13:48 +02:00
@@ -7,7 +7,6 @@
  * published by the Free Software Foundation.
  */

-
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ipv6.h>
@@ -20,8 +19,6 @@
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_opts.h>

-#define LOW(n) (n & 0x00FF)
-
#define HOPBYHOP 0

MODULE_LICENSE("GPL");
@@ -48,8 +45,8 @@

  *  	0	-> invariant
  *  	1	-> can change the routing
  *  (Type & 0x1F) Type
- *      0	-> PAD0 (only 1 byte!)
- *      1	-> PAD1 LENGTH info (total length = length + 2)
+ *      0	-> Pad1 (only 1 byte!)
+ *      1	-> PadN LENGTH info (total length = length + 2)
  *      C0 | 2	-> JUMBO 4 x x x x ( xxxx > 64k )
  *      5	-> RTALERT 2 x x
  */
@@ -71,7 +68,8 @@
        unsigned int ptr;
        unsigned int hdrlen = 0;
        unsigned int ret = 0;
-       u_int16_t *optdesc = NULL;
+       u8 *opttype = NULL;
+       unsigned int optlen;

        /* type of the 1st exthdr */
        nexthdr = skb->nh.ipv6h->nexthdr;
@@ -98,7 +96,7 @@
                      break;
               }

- hdr=(void *)(skb->data)+ptr;
+ hdr = (void *)(skb->data + ptr);

               /* Calculate the header length */
                 if (nexthdr == NEXTHDR_FRAGMENT) {
@@ -160,7 +158,7 @@
        		return 0;
        }

- optsh=(void *)(skb->data)+ptr;
+ optsh = (void *)(skb->data + ptr);

        DEBUGP("IPv6 OPTS LEN %u %u ", hdrlen, optsh->hdrlen);

@@ -176,7 +174,6 @@

                            ((optinfo->hdrlen == hdrlen) ^
                            !!(optinfo->invflags & IP6T_OPTS_INV_LEN)));

-       temp = len = 0;
        ptr += 2;
        hdrlen -= 2;
        if ( !(optinfo->flags & IP6T_OPTS_OPTS) ){

@@ -187,48 +184,52 @@
DEBUGP("Strict ");
DEBUGP("#%d ",optinfo->optsnr);
for(temp=0; temp<optinfo->optsnr; temp++){
- optdesc = (void *)(skb->data)+ptr;
+ /* type field exists ? */
+ if (ptr > skb->len - 1 || hdrlen < 1)
+ break;
+ opttype = (void *)(skb->data + ptr);
+
/* Type check */
- if ( (unsigned char)*optdesc !=
- (optinfo->opts[temp] & 0xFF00)>>8 ){
+ if (*opttype != (optinfo->opts[temp] & 0xFF00)>>8){
DEBUGP("Tbad %02X %02X\n",
- (unsigned char)*optdesc,
- (optinfo->opts[temp] &
- 0xFF00)>>8);
+ *opttype,
+ (optinfo->opts[temp] & 0xFF00)>>8);
return 0;
} else {
DEBUGP("Tok ");
}
/* Length check */
- if (((optinfo->opts[temp] & 0x00FF) != 0xFF) &&
- (unsigned char)*optdesc != 0){
- if ( ntohs((u16)*optdesc) !=
- optinfo->opts[temp] ){
- DEBUGP("Lbad %02X %04X %04X\n",
- (unsigned char)*optdesc,
- ntohs((u16)*optdesc),
- optinfo->opts[temp]);
+ if (*opttype) {
+ u16 spec_len;
+
+ /* length field exists ? */
+ if (ptr > skb->len - 2 || hdrlen < 2)
+ break;
+ optlen = *((u8 *)(skb->data + ptr + 1));
+ spec_len = optinfo->opts[temp] & 0x00FF;
+
+ if (spec_len != 0x00FF && spec_len != optlen) {
+ DEBUGP("Lbad %02X %04X\n", optlen,
+ spec_len);
return 0;
- } else {
- DEBUGP("Lok ");
}
- }
- /* Step to the next */
- if ((unsigned char)*optdesc == 0){
- DEBUGP("PAD0 \n");
- ptr++;
- hdrlen--;
+ DEBUGP("Lok ");
+ optlen += 2;
} else {
- ptr += LOW(ntohs(*optdesc));
- hdrlen -= LOW(ntohs(*optdesc));
- DEBUGP("len%04X \n",
- LOW(ntohs(*optdesc)));
+ DEBUGP("Pad1\n");
+ optlen = 1;
}
- if (ptr > skb->len || ( !hdrlen &&
- (temp != optinfo->optsnr - 1))) {
+
+ /* Step to the next */
+ DEBUGP("len%04X \n", optlen);
+
+ if ((ptr > skb->len - optlen || hdrlen < optlen) &&
+ (temp < optinfo->optsnr - 1)) {
DEBUGP("new pointer is too large! \n"); break;
}
+ ptr += optlen;
+ hdrlen -= optlen;
}
if (temp == optinfo->optsnr)
return ret;
@@ -270,6 +271,7 @@
#endif
.match = &match,
.checkentry = &checkentry,
+ .me = THIS_MODULE,
};

static int __init init(void)