patch-2.4.21 linux-2.4.21/net/ipv6/netfilter/ip6t_frag.c

• Lines: 240
• Date: 2003-06-13 07:51:39.000000000 -0700
• Orig file: linux-2.4.20/net/ipv6/netfilter/ip6t_frag.c
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.20/net/ipv6/netfilter/ip6t_frag.c linux-2.4.21/net/ipv6/netfilter/ip6t_frag.c
@@ -0,0 +1,239 @@
+/* Kernel module to match FRAG 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_frag.h>
+
+EXPORT_NO_SYMBOLS;
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("IPv6 FRAG match");
+MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+#if 0
+#if     BYTE_ORDER == BIG_ENDIAN
+#define IP6F_OFF_MASK       0xfff8  /* mask out offset from _offlg */
+#define IP6F_RESERVED_MASK  0x0006  /* reserved bits in ip6f_offlg */
+#define IP6F_MORE_FRAG      0x0001  /* more-fragments flag */
+#else   /* BYTE_ORDER == LITTLE_ENDIAN */
+#define IP6F_OFF_MASK       0xf8ff  /* mask out offset from _offlg */
+#define IP6F_RESERVED_MASK  0x0600  /* reserved bits in ip6f_offlg */
+#define IP6F_MORE_FRAG      0x0100  /* more-fragments flag */
+#endif
+#endif
+
+#define IP6F_OFF_MASK       0xf8ff  /* mask out offset from _offlg */
+#define IP6F_RESERVED_MASK  0x0600  /* reserved bits in ip6f_offlg */
+#define IP6F_MORE_FRAG      0x0100  /* more-fragments flag */
+
+struct fraghdr {
+       __u8    nexthdr;
+       __u8    hdrlen;
+       __u16   info;
+       __u32   id;
+};
+
+/* Returns 1 if the id is matched by the range, 0 otherwise */
+static inline int
+id_match(u_int32_t min, u_int32_t max, u_int32_t id, int invert)
+{
+       int r=0;
+       DEBUGP("frag id_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
+              min,id,max);
+       r=(id >= min && id <= max) ^ invert;
+       DEBUGP(" result %s\n",r? "PASS" : "FAILED");
+       return r;
+}
+
+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 fraghdr *frag = NULL;
+       const struct ip6t_frag *fraginfo = matchinfo;
+       unsigned int temp;
+       int len;
+       u8 nexthdr;
+       unsigned int ptr;
+       unsigned int hdrlen = 0;
+
+       /* 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_frag 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=(struct ipv6_opt_hdr *)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);
+
+              /* FRAG -> evaluate */
+                if (nexthdr == NEXTHDR_FRAGMENT) {
+                     temp |= MASK_FRAGMENT;
+                     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_frag match: unknown nextheader %u\n",nexthdr);
+                            return 0;
+                            break;
+              }
+
+                nexthdr = hdr->nexthdr;
+                len -= hdrlen;
+                ptr += hdrlen;
+		if ( ptr > skb->len ) {
+			DEBUGP("ipv6_frag: new pointer too large! \n");
+			break;
+		}
+        }
+
+       /* FRAG header not found */
+       if ( temp != MASK_FRAGMENT ) return 0;
+
+       if (len < (int)sizeof(struct fraghdr)){
+	       *hotdrop = 1;
+       		return 0;
+       }
+
+       frag=skb->data+ptr;
+
+       DEBUGP("IPv6 FRAG LEN %u %u ", hdrlen, frag->hdrlen);
+       DEBUGP("INFO %04X ", frag->info);
+       DEBUGP("OFFSET %04X ", frag->info & IP6F_OFF_MASK);
+       DEBUGP("RES %04X ", frag->info & IP6F_RESERVED_MASK);
+       DEBUGP("MF %04X ", frag->info & IP6F_MORE_FRAG);
+       DEBUGP("ID %u %08X\n", ntohl(frag->id), ntohl(frag->id));
+
+       DEBUGP("IPv6 FRAG id %02X ",
+       		(id_match(fraginfo->ids[0], fraginfo->ids[1],
+                           ntohl(frag->id),
+                           !!(fraginfo->invflags & IP6T_FRAG_INV_IDS))));
+       DEBUGP("len %02X %04X %02X ",
+       		fraginfo->hdrlen, hdrlen,
+       		(!fraginfo->hdrlen ||
+                           (fraginfo->hdrlen == hdrlen) ^
+                           !!(fraginfo->invflags & IP6T_FRAG_INV_LEN)));
+       DEBUGP("res %02X %02X %02X ", 
+       		(fraginfo->flags & IP6T_FRAG_RES), frag->info & IP6F_RESERVED_MASK,
+       		!((fraginfo->flags & IP6T_FRAG_RES) && (frag->info & IP6F_RESERVED_MASK)));
+       DEBUGP("first %02X %02X %02X ", 
+       		(fraginfo->flags & IP6T_FRAG_FST), frag->info & IP6F_OFF_MASK,
+       		!((fraginfo->flags & IP6T_FRAG_FST) && (frag->info & IP6F_OFF_MASK)));
+       DEBUGP("mf %02X %02X %02X ", 
+       		(fraginfo->flags & IP6T_FRAG_MF), frag->info & IP6F_MORE_FRAG,
+       		!((fraginfo->flags & IP6T_FRAG_MF) && !((frag->info & IP6F_MORE_FRAG))));
+       DEBUGP("last %02X %02X %02X\n", 
+       		(fraginfo->flags & IP6T_FRAG_NMF), frag->info & IP6F_MORE_FRAG,
+       		!((fraginfo->flags & IP6T_FRAG_NMF) && (frag->info & IP6F_MORE_FRAG)));
+
+       return (frag != NULL)
+       		&&
+       		(id_match(fraginfo->ids[0], fraginfo->ids[1],
+                           ntohl(frag->id),
+                           !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)))
+		&&
+	      	(!fraginfo->hdrlen ||
+                           (fraginfo->hdrlen == hdrlen) ^
+                           !!(fraginfo->invflags & IP6T_FRAG_INV_LEN))
+		&&
+		!((fraginfo->flags & IP6T_FRAG_RES) && (frag->info & IP6F_RESERVED_MASK))
+		&&
+		!((fraginfo->flags & IP6T_FRAG_FST) && (frag->info & IP6F_OFF_MASK))
+		&&
+		!((fraginfo->flags & IP6T_FRAG_MF) && !((frag->info & IP6F_MORE_FRAG)))
+		&&
+		!((fraginfo->flags & IP6T_FRAG_NMF) && (frag->info & IP6F_MORE_FRAG));
+}
+
+/* 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_frag *fraginfo = matchinfo;
+
+       if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_frag))) {
+              DEBUGP("ip6t_frag: matchsize %u != %u\n",
+                      matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_frag)));
+              return 0;
+       }
+       if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
+              DEBUGP("ip6t_frag: unknown flags %X\n",
+                      fraginfo->invflags);
+              return 0;
+       }
+
+       return 1;
+}
+
+static struct ip6t_match frag_match
+= { { NULL, NULL }, "frag", &match, &checkentry, NULL, THIS_MODULE };
+
+static int __init init(void)
+{
+       return ip6t_register_match(&frag_match);
+}
+
+static void __exit cleanup(void)
+{
+       ip6t_unregister_match(&frag_match);
+}
+
+module_init(init);
+module_exit(cleanup);