[NETFILTER]: make ipv6_find_hdr() find transport protocol header

The original ipv6_find_hdr() finds the specified header in IPv6 packets.
This makes it possible to get transport header so that we can kill similar
loop in ip6_match_packet().

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

7 files changed, 48 insertions, 74 deletions

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index ea43ef1d94a7..13b1a525b92c 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -205,69 +205,21 @@ ip6_packet_match(const struct sk_buff *skb,
 
         /* look for the desired protocol header */
         if((ip6info->flags & IP6T_F_PROTO)) {
-                u_int8_t currenthdr = ipv6->nexthdr;
-                struct ipv6_opt_hdr _hdr, *hp;
-                u_int16_t ptr;          /* Header offset in skb */
-                u_int16_t hdrlen;       /* Header */
-                u_int16_t _fragoff = 0, *fp = NULL;
-
-                ptr = IPV6_HDR_LEN;
-
-                while (ip6t_ext_hdr(currenthdr)) {
-                        /* Is there enough space for the next ext header? */
-                        if (skb->len - ptr < IPV6_OPTHDR_LEN)
-                                return 0;
-
-                        /* NONE or ESP: there isn't protocol part */
-                        /* If we want to count these packets in '-p all',
-                         * we will change the return 0 to 1*/
-                        if ((currenthdr == IPPROTO_NONE) || 
-                                (currenthdr == IPPROTO_ESP))
-                                break;
+                int protohdr;
+                unsigned short _frag_off;
 
-                        hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
-                        BUG_ON(hp == NULL);
-
-                        /* Size calculation */
-                        if (currenthdr == IPPROTO_FRAGMENT) {
-                                fp = skb_header_pointer(skb,
-                                                   ptr+offsetof(struct frag_hdr,
-                                                                frag_off),
-                                                   sizeof(_fragoff),
-                                                   &_fragoff);
-                                if (fp == NULL)
-                                        return 0;
-
-                                _fragoff = ntohs(*fp) & ~0x7;
-                                hdrlen = 8;
-                        } else if (currenthdr == IPPROTO_AH)
-                                hdrlen = (hp->hdrlen+2)<<2;
-                        else
-                                hdrlen = ipv6_optlen(hp);
-
-                        currenthdr = hp->nexthdr;
-                        ptr += hdrlen;
-                        /* ptr is too large */
-                        if ( ptr > skb->len ) 
-                                return 0;
-                        if (_fragoff) {
-                                if (ip6t_ext_hdr(currenthdr))
-                                        return 0;
-                                break;
-                        }
-                }
-
-                *protoff = ptr;
-                *fragoff = _fragoff;
+                protohdr = ipv6_find_hdr(skb, protoff, -1, &_frag_off);
+                if (protohdr < 0)
+                        return 0;
 
-                /* currenthdr contains the protocol header */
+                *fragoff = _frag_off;
 
                 dprintf("Packet protocol %hi ?= %s%hi.\n",
-                                currenthdr, 
+                                protohdr, 
                                 ip6info->invflags & IP6T_INV_PROTO ? "!":"",
                                 ip6info->proto);
 
-                if (ip6info->proto == currenthdr) {
+                if (ip6info->proto == protohdr) {
                         if(ip6info->invflags & IP6T_INV_PROTO) {
                                 return 0;
                         }
@@ -2098,26 +2050,39 @@ static void __exit fini(void)
 }
 
 /*
- * find specified header up to transport protocol header.
- * If found target header, the offset to the header is set to *offset
- * and return 0. otherwise, return -1.
+ * find the offset to specified header or the protocol number of last header
+ * if target < 0. "last header" is transport protocol header, ESP, or
+ * "No next header".
+ *
+ * If target header is found, its offset is set in *offset and return protocol
+ * number. Otherwise, return -1.
+ *
+ * Note that non-1st fragment is special case that "the protocol number
+ * of last header" is "next header" field in Fragment header. In this case,
+ * *offset is meaningless and fragment offset is stored in *fragoff if fragoff
+ * isn't NULL.
  *
- * Notes: - non-1st Fragment Header isn't skipped.
- *        - ESP header isn't skipped.
- *        - The target header may be trancated.
  */
-int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset, u8 target)
+int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
+                  int target, unsigned short *fragoff)
 {
         unsigned int start = (u8*)(skb->nh.ipv6h + 1) - skb->data;
         u8 nexthdr = skb->nh.ipv6h->nexthdr;
         unsigned int len = skb->len - start;
 
+        if (fragoff)
+                *fragoff = 0;
+
         while (nexthdr != target) {
                 struct ipv6_opt_hdr _hdr, *hp;
                 unsigned int hdrlen;
 
-                if ((!ipv6_ext_hdr(nexthdr)) || nexthdr == NEXTHDR_NONE)
+                if ((!ipv6_ext_hdr(nexthdr)) || nexthdr == NEXTHDR_NONE) {
+                        if (target < 0)
+                                break;
                         return -1;
+                }
+
                 hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
                 if (hp == NULL)
                         return -1;
@@ -2131,8 +2096,17 @@ int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset, u8 target)
                         if (fp == NULL)
                                 return -1;
 
-                        if (ntohs(*fp) & ~0x7)
+                        _frag_off = ntohs(*fp) & ~0x7;
+                        if (_frag_off) {
+                                if (target < 0 &&
+                                    ((!ipv6_ext_hdr(hp->nexthdr)) ||
+                                     nexthdr == NEXTHDR_NONE)) {
+                                        if (fragoff)
+                                                *fragoff = _frag_off;
+                                        return hp->nexthdr;
+                                }
                                 return -1;
+                        }
                         hdrlen = 8;
                 } else if (nexthdr == NEXTHDR_AUTH)
                         hdrlen = (hp->hdrlen + 2) << 2; 
@@ -2145,7 +2119,7 @@ int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset, u8 target)
         }
 
         *offset = start;
-        return 0;
+        return nexthdr;
 }
 
 EXPORT_SYMBOL(ip6t_register_table);
diff --git a/net/ipv6/netfilter/ip6t_ah.c b/net/ipv6/netfilter/ip6t_ah.c
index 268918d5deea..f5c1a7ff4a1f 100644
--- a/net/ipv6/netfilter/ip6t_ah.c
+++ b/net/ipv6/netfilter/ip6t_ah.c
@@ -54,7 +54,7 @@ match(const struct sk_buff *skb,
         unsigned int ptr;
         unsigned int hdrlen = 0;
 
-        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_AUTH) < 0)
+        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_AUTH, NULL) < 0)
                 return 0;
 
         ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah);
diff --git a/net/ipv6/netfilter/ip6t_dst.c b/net/ipv6/netfilter/ip6t_dst.c
index c450a635e54b..48cf5f9efc95 100644
--- a/net/ipv6/netfilter/ip6t_dst.c
+++ b/net/ipv6/netfilter/ip6t_dst.c
@@ -71,9 +71,9 @@ match(const struct sk_buff *skb,
        unsigned int optlen;
        
 #if HOPBYHOP
-        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_HOP) < 0)
+        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_HOP, NULL) < 0)
 #else
-        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_DEST) < 0)
+        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_DEST, NULL) < 0)
 #endif
                 return 0;
 
diff --git a/net/ipv6/netfilter/ip6t_esp.c b/net/ipv6/netfilter/ip6t_esp.c
index 65937de1b58c..e1828f6d0a40 100644
--- a/net/ipv6/netfilter/ip6t_esp.c
+++ b/net/ipv6/netfilter/ip6t_esp.c
@@ -56,7 +56,7 @@ match(const struct sk_buff *skb,
         /* Make sure this isn't an evil packet */
         /*DEBUGP("ipv6_esp entered \n");*/
 
-        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_ESP) < 0)
+        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_ESP, NULL) < 0)
                 return 0;
 
         eh = skb_header_pointer(skb, ptr, sizeof(_esp), &_esp);
diff --git a/net/ipv6/netfilter/ip6t_frag.c b/net/ipv6/netfilter/ip6t_frag.c
index 085d5f8eea29..d1549b268669 100644
--- a/net/ipv6/netfilter/ip6t_frag.c
+++ b/net/ipv6/netfilter/ip6t_frag.c
@@ -52,7 +52,7 @@ match(const struct sk_buff *skb,
        const struct ip6t_frag *fraginfo = matchinfo;
        unsigned int ptr;
 
-        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT) < 0)
+        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL) < 0)
                 return 0;
 
         fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
diff --git a/net/ipv6/netfilter/ip6t_hbh.c b/net/ipv6/netfilter/ip6t_hbh.c
index 1d09485111d0..e3bc8e2700e7 100644
--- a/net/ipv6/netfilter/ip6t_hbh.c
+++ b/net/ipv6/netfilter/ip6t_hbh.c
@@ -71,9 +71,9 @@ match(const struct sk_buff *skb,
        unsigned int optlen;
        
 #if HOPBYHOP
-        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_HOP) < 0)
+        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_HOP, NULL) < 0)
 #else
-        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_DEST) < 0)
+        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_DEST, NULL) < 0)
 #endif
                 return 0;
 
diff --git a/net/ipv6/netfilter/ip6t_rt.c b/net/ipv6/netfilter/ip6t_rt.c
index beb2fd5cebbb..c1e770e45543 100644
--- a/net/ipv6/netfilter/ip6t_rt.c
+++ b/net/ipv6/netfilter/ip6t_rt.c
@@ -58,7 +58,7 @@ match(const struct sk_buff *skb,
        unsigned int ret = 0;
        struct in6_addr *ap, _addr;
 
-        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING) < 0)
+        if (ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL) < 0)
                 return 0;
 
        rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);