patch-2.4.21 linux-2.4.21/net/ipv6/netfilter/ip6t_dst.c

• Lines: 277
• Date: 2003-06-13 07:51:39.000000000 -0700
• Orig file: linux-2.4.20/net/ipv6/netfilter/ip6t_dst.c
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.20/net/ipv6/netfilter/ip6t_dst.c linux-2.4.21/net/ipv6/netfilter/ip6t_dst.c
@@ -0,0 +1,276 @@
+/* Kernel module to match Hop-by-Hop and Destination parameters. */
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ipv6.h>
+#include <linux/types.h>
+#include <net/checksum.h>
+#include <net/ipv6.h>
+
+#include <asm/byteorder.h>
+
+#include <linux/netfilter_ipv6/ip6_tables.h>
+#include <linux/netfilter_ipv6/ip6t_opts.h>
+
+#define LOW(n)		(n & 0x00FF)
+
+#define HOPBYHOP	0
+
+EXPORT_NO_SYMBOLS;
+MODULE_LICENSE("GPL");
+#if HOPBYHOP
+MODULE_DESCRIPTION("IPv6 HbH match");
+#else
+MODULE_DESCRIPTION("IPv6 DST match");
+#endif
+MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+/*
+ * (Type & 0xC0) >> 6
+ * 	0	-> ignorable
+ * 	1	-> must drop the packet
+ * 	2	-> send ICMP PARM PROB regardless and drop packet
+ * 	3	-> Send ICMP if not a multicast address and drop packet
+ *  (Type & 0x20) >> 5
+ *  	0	-> invariant
+ *  	1	-> can change the routing
+ *  (Type & 0x1F) Type
+ *      0	-> PAD0 (only 1 byte!)
+ *      1	-> PAD1 LENGTH info (total length = length + 2)
+ *      C0 | 2	-> JUMBO 4 x x x x ( xxxx > 64k )
+ *      5	-> RTALERT 2 x x
+ */
+
+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 *protohdr,
+      u_int16_t datalen,
+      int *hotdrop)
+{
+       struct ipv6_opt_hdr *optsh = NULL;
+       const struct ip6t_opts *optinfo = matchinfo;
+       unsigned int temp;
+       unsigned int len;
+       u8 nexthdr;
+       unsigned int ptr;
+       unsigned int hdrlen = 0;
+       unsigned int ret = 0;
+       u_int16_t *optdesc = NULL;
+       
+       /* type of the 1st exthdr */
+       nexthdr = skb->nh.ipv6h->nexthdr;
+       /* pointer to the 1st exthdr */
+       ptr = sizeof(struct ipv6hdr);
+       /* available length */
+       len = skb->len - ptr;
+       temp = 0;
+
+        while (ip6t_ext_hdr(nexthdr)) {
+               struct ipv6_opt_hdr *hdr;
+
+              DEBUGP("ipv6_opts header iteration \n");
+
+              /* Is there enough space for the next ext header? */
+                if (len < (int)sizeof(struct ipv6_opt_hdr))
+                        return 0;
+              /* No more exthdr -> evaluate */
+                if (nexthdr == NEXTHDR_NONE) {
+                     break;
+              }
+              /* ESP -> evaluate */
+                if (nexthdr == NEXTHDR_ESP) {
+                     break;
+              }
+
+              hdr=(void *)(skb->data)+ptr;
+
+              /* Calculate the header length */
+                if (nexthdr == NEXTHDR_FRAGMENT) {
+                        hdrlen = 8;
+                } else if (nexthdr == NEXTHDR_AUTH)
+                        hdrlen = (hdr->hdrlen+2)<<2;
+                else
+                        hdrlen = ipv6_optlen(hdr);
+
+              /* OPTS -> evaluate */
+#if HOPBYHOP
+                if (nexthdr == NEXTHDR_HOP) {
+                     temp |= MASK_HOPOPTS;
+#else
+                if (nexthdr == NEXTHDR_DEST) {
+                     temp |= MASK_DSTOPTS;
+#endif
+                     break;
+              }
+
+
+              /* set the flag */
+              switch (nexthdr){
+                     case NEXTHDR_HOP:
+                     case NEXTHDR_ROUTING:
+                     case NEXTHDR_FRAGMENT:
+                     case NEXTHDR_AUTH:
+                     case NEXTHDR_DEST:
+                            break;
+                     default:
+                            DEBUGP("ipv6_opts match: unknown nextheader %u\n",nexthdr);
+                            return 0;
+                            break;
+              }
+
+                nexthdr = hdr->nexthdr;
+                len -= hdrlen;
+                ptr += hdrlen;
+		if ( ptr > skb->len ) {
+			DEBUGP("ipv6_opts: new pointer is too large! \n");
+			break;
+		}
+        }
+
+       /* OPTIONS header not found */
+#if HOPBYHOP
+       if ( temp != MASK_HOPOPTS ) return 0;
+#else
+       if ( temp != MASK_DSTOPTS ) return 0;
+#endif
+
+       if (len < (int)sizeof(struct ipv6_opt_hdr)){
+	       *hotdrop = 1;
+       		return 0;
+       }
+
+       if (len < hdrlen){
+	       /* Packet smaller than it's length field */
+       		return 0;
+       }
+
+       optsh=(void *)(skb->data)+ptr;
+
+       DEBUGP("IPv6 OPTS LEN %u %u ", hdrlen, optsh->hdrlen);
+
+       DEBUGP("len %02X %04X %02X ",
+       		optinfo->hdrlen, hdrlen,
+       		(!(optinfo->flags & IP6T_OPTS_LEN) ||
+                           ((optinfo->hdrlen == hdrlen) ^
+                           !!(optinfo->invflags & IP6T_OPTS_INV_LEN))));
+
+       ret = (optsh != NULL)
+       		&&
+	      	(!(optinfo->flags & IP6T_OPTS_LEN) ||
+                           ((optinfo->hdrlen == hdrlen) ^
+                           !!(optinfo->invflags & IP6T_OPTS_INV_LEN)));
+
+       temp = len = 0;
+       ptr += 2;
+       hdrlen -= 2;
+       if ( !(optinfo->flags & IP6T_OPTS_OPTS) ){
+	       return ret;
+	} else if (optinfo->flags & IP6T_OPTS_NSTRICT) {
+		DEBUGP("Not strict - not implemented");
+	} else {
+		DEBUGP("Strict ");
+		DEBUGP("#%d ",optinfo->optsnr);
+		for(temp=0; temp<optinfo->optsnr; temp++){
+			optdesc = (void *)(skb->data)+ptr;
+			/* Type check */
+			if ( (unsigned char)*optdesc != 
+				(optinfo->opts[temp] & 0xFF00)>>8 ){
+				DEBUGP("Tbad %02X %02X\n",
+						(unsigned char)*optdesc,
+						(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]);
+					return 0;
+				} else {
+					DEBUGP("Lok ");
+				}
+			}
+			/* Step to the next */
+			if ((unsigned char)*optdesc == 0){
+				DEBUGP("PAD0 \n");
+				ptr++;
+				hdrlen--;
+			} else {
+				ptr += LOW(ntohs(*optdesc));
+				hdrlen -= LOW(ntohs(*optdesc));
+				DEBUGP("len%04X \n", 
+					LOW(ntohs(*optdesc)));
+			}
+			if (ptr > skb->len || ( !hdrlen && 
+				(temp != optinfo->optsnr - 1))) {
+				DEBUGP("new pointer is too large! \n");
+				break;
+			}
+		}
+		if (temp == optinfo->optsnr)
+			return ret;
+		else return 0;
+	}
+
+	return 0;
+}
+
+/* Called when user tries to insert an entry of this type. */
+static int
+checkentry(const char *tablename,
+          const struct ip6t_ip6 *ip,
+          void *matchinfo,
+          unsigned int matchinfosize,
+          unsigned int hook_mask)
+{
+       const struct ip6t_opts *optsinfo = matchinfo;
+
+       if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_opts))) {
+              DEBUGP("ip6t_opts: matchsize %u != %u\n",
+                      matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_opts)));
+              return 0;
+       }
+       if (optsinfo->invflags & ~IP6T_OPTS_INV_MASK) {
+              DEBUGP("ip6t_opts: unknown flags %X\n",
+                      optsinfo->invflags);
+              return 0;
+       }
+
+       return 1;
+}
+
+static struct ip6t_match opts_match
+#if HOPBYHOP
+= { { NULL, NULL }, "hbh", &match, &checkentry, NULL, THIS_MODULE };
+#else
+= { { NULL, NULL }, "dst", &match, &checkentry, NULL, THIS_MODULE };
+#endif
+
+static int __init init(void)
+{
+       return ip6t_register_match(&opts_match);
+}
+
+static void __exit cleanup(void)
+{
+       ip6t_unregister_match(&opts_match);
+}
+
+module_init(init);
+module_exit(cleanup);