patch-2.4.21 linux-2.4.21/net/ipv6/netfilter/ip6t_ah.c

• Lines: 208
• Date: 2003-06-13 07:51:39.000000000 -0700
• Orig file: linux-2.4.20/net/ipv6/netfilter/ip6t_ah.c
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.20/net/ipv6/netfilter/ip6t_ah.c linux-2.4.21/net/ipv6/netfilter/ip6t_ah.c
@@ -0,0 +1,207 @@
+/* Kernel module to match AH 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 <linux/netfilter_ipv6/ip6_tables.h>
+#include <linux/netfilter_ipv6/ip6t_ah.h>
+
+EXPORT_NO_SYMBOLS;
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("IPv6 AH match");
+MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+struct ahhdr {
+       __u8    nexthdr;
+       __u8    hdrlen;
+       __u16   reserved;
+       __u32   spi;
+};
+
+/* Returns 1 if the spi is matched by the range, 0 otherwise */
+static inline int
+spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert)
+{
+       int r=0;
+       DEBUGP("ah spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
+              min,spi,max);
+       r=(spi >= min && spi <= max) ^ invert;
+       DEBUGP(" result %s\n",r? "PASS\n" : "FAILED\n");
+       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 ahhdr *ah = NULL;
+       const struct ip6t_ah *ahinfo = matchinfo;
+       unsigned int temp;
+       int len;
+       u8 nexthdr;
+       unsigned int ptr;
+       unsigned int hdrlen = 0;
+
+       /*DEBUGP("IPv6 AH entered\n");*/
+       /* if (opt->auth == 0) return 0;
+       * It does not filled on output */
+
+       /* 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_ah 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);
+
+              /* AH -> evaluate */
+                if (nexthdr == NEXTHDR_AUTH) {
+                     temp |= MASK_AH;
+                     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_ah match: unknown nextheader %u\n",nexthdr);
+                            return 0;
+                            break;
+              }
+
+                nexthdr = hdr->nexthdr;
+                len -= hdrlen;
+                ptr += hdrlen;
+		if ( ptr > skb->len ) {
+			DEBUGP("ipv6_ah: new pointer too large! \n");
+			break;
+		}
+        }
+
+       /* AH header not found */
+       if ( temp != MASK_AH ) return 0;
+
+       if (len < (int)sizeof(struct ahhdr)){
+	       *hotdrop = 1;
+       		return 0;
+       }
+
+       ah=skb->data+ptr;
+
+       DEBUGP("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen);
+       DEBUGP("RES %04X ", ah->reserved);
+       DEBUGP("SPI %u %08X\n", ntohl(ah->spi), ntohl(ah->spi));
+
+       DEBUGP("IPv6 AH spi %02X ",
+       		(spi_match(ahinfo->spis[0], ahinfo->spis[1],
+                           ntohl(ah->spi),
+                           !!(ahinfo->invflags & IP6T_AH_INV_SPI))));
+       DEBUGP("len %02X %04X %02X ",
+       		ahinfo->hdrlen, hdrlen,
+       		(!ahinfo->hdrlen ||
+                           (ahinfo->hdrlen == hdrlen) ^
+                           !!(ahinfo->invflags & IP6T_AH_INV_LEN)));
+       DEBUGP("res %02X %04X %02X\n", 
+       		ahinfo->hdrres, ah->reserved,
+       		!(ahinfo->hdrres && ah->reserved));
+
+       return (ah != NULL)
+              &&
+              (spi_match(ahinfo->spis[0], ahinfo->spis[1],
+                           ntohl(ah->spi),
+                           !!(ahinfo->invflags & IP6T_AH_INV_SPI)))
+              &&
+              (!ahinfo->hdrlen ||
+                           (ahinfo->hdrlen == hdrlen) ^
+                           !!(ahinfo->invflags & IP6T_AH_INV_LEN))
+              &&
+              !(ahinfo->hdrres && ah->reserved);
+}
+
+/* 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_ah *ahinfo = matchinfo;
+
+       if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_ah))) {
+              DEBUGP("ip6t_ah: matchsize %u != %u\n",
+                      matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_ah)));
+              return 0;
+       }
+       if (ahinfo->invflags & ~IP6T_AH_INV_MASK) {
+              DEBUGP("ip6t_ah: unknown flags %X\n",
+                      ahinfo->invflags);
+              return 0;
+       }
+
+       return 1;
+}
+
+static struct ip6t_match ah_match
+= { { NULL, NULL }, "ah", &match, &checkentry, NULL, THIS_MODULE };
+
+static int __init init(void)
+{
+       return ip6t_register_match(&ah_match);
+}
+
+static void __exit cleanup(void)
+{
+       ip6t_unregister_match(&ah_match);
+}
+
+module_init(init);
+module_exit(cleanup);