[IPV6]: Link some packet walker helpers always statically.

Put the extension header helper funcs always statically into
the kernel even if ipv6 is built as a module, this is needed
for things like SELinux.

net/Makefile

@@ -16,7 +16,9 @@ obj-$(CONFIG_LLC)		+= llc/
 obj-$(CONFIG_NET)		+= ethernet/ 802/ sched/ netlink/
 obj-$(CONFIG_INET)		+= ipv4/ xfrm/
 obj-$(CONFIG_UNIX)		+= unix/
-obj-$(CONFIG_IPV6)		+= ipv6/
+ifneq ($(CONFIG_IPV6),)
+obj-y				+= ipv6/
+endif
 obj-$(CONFIG_PACKET)		+= packet/
 obj-$(CONFIG_NET_KEY)		+= key/
 obj-$(CONFIG_NET_SCHED)		+= sched/

net/ipv6/Makefile

@@ -19,3 +19,5 @@ obj-$(CONFIG_INET6_IPCOMP) += ipcomp6.o
 obj-$(CONFIG_NETFILTER)	+= netfilter/
 
 obj-$(CONFIG_IPV6_TUNNEL) += ip6_tunnel.o
+
+obj-y += exthdrs_core.o

net/ipv6/exthdrs.c

@@ -633,105 +633,3 @@ ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
 	}
 	return opt2;
 }
-
-
-/* 
- * find out if nexthdr is a well-known extension header or a protocol
- */
-
-int ipv6_ext_hdr(u8 nexthdr)
-{
-	/* 
-	 * find out if nexthdr is an extension header or a protocol
-	 */
-	return ( (nexthdr == NEXTHDR_HOP)	||
-		 (nexthdr == NEXTHDR_ROUTING)	||
-		 (nexthdr == NEXTHDR_FRAGMENT)	||
-		 (nexthdr == NEXTHDR_AUTH)	||
-		 (nexthdr == NEXTHDR_NONE)	||
-		 (nexthdr == NEXTHDR_DEST) );
-}
-
-/*
- * Skip any extension headers. This is used by the ICMP module.
- *
- * Note that strictly speaking this conflicts with RFC 2460 4.0:
- * ...The contents and semantics of each extension header determine whether 
- * or not to proceed to the next header.  Therefore, extension headers must
- * be processed strictly in the order they appear in the packet; a
- * receiver must not, for example, scan through a packet looking for a
- * particular kind of extension header and process that header prior to
- * processing all preceding ones.
- * 
- * We do exactly this. This is a protocol bug. We can't decide after a
- * seeing an unknown discard-with-error flavour TLV option if it's a 
- * ICMP error message or not (errors should never be send in reply to
- * ICMP error messages).
- * 
- * But I see no other way to do this. This might need to be reexamined
- * when Linux implements ESP (and maybe AUTH) headers.
- * --AK
- *
- * This function parses (probably truncated) exthdr set "hdr"
- * of length "len". "nexthdrp" initially points to some place,
- * where type of the first header can be found.
- *
- * It skips all well-known exthdrs, and returns pointer to the start
- * of unparsable area i.e. the first header with unknown type.
- * If it is not NULL *nexthdr is updated by type/protocol of this header.
- *
- * NOTES: - if packet terminated with NEXTHDR_NONE it returns NULL.
- *        - it may return pointer pointing beyond end of packet,
- *	    if the last recognized header is truncated in the middle.
- *        - if packet is truncated, so that all parsed headers are skipped,
- *	    it returns NULL.
- *	  - First fragment header is skipped, not-first ones
- *	    are considered as unparsable.
- *	  - ESP is unparsable for now and considered like
- *	    normal payload protocol.
- *	  - Note also special handling of AUTH header. Thanks to IPsec wizards.
- *
- * --ANK (980726)
- */
-
-int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp, int len)
-{
-	u8 nexthdr = *nexthdrp;
-
-	while (ipv6_ext_hdr(nexthdr)) {
-		struct ipv6_opt_hdr hdr;
-		int hdrlen;
-
-		if (len < (int)sizeof(struct ipv6_opt_hdr))
-			return -1;
-		if (nexthdr == NEXTHDR_NONE)
-			return -1;
-		if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
-			BUG();
-		if (nexthdr == NEXTHDR_FRAGMENT) {
-			unsigned short frag_off;
-			if (skb_copy_bits(skb,
-					  start+offsetof(struct frag_hdr,
-							 frag_off),
-					  &frag_off,
-					  sizeof(frag_off))) {
-				return -1;
-			}
-
-			if (ntohs(frag_off) & ~0x7)
-				break;
-			hdrlen = 8;
-		} else if (nexthdr == NEXTHDR_AUTH)
-			hdrlen = (hdr.hdrlen+2)<<2; 
-		else
-			hdrlen = ipv6_optlen(&hdr); 
-
-		nexthdr = hdr.nexthdr;
-		len -= hdrlen;
-		start += hdrlen;
-	}
-
-	*nexthdrp = nexthdr;
-	return start;
-}
-

net/ipv6/exthdrs_core.c

+/*
+ * IPv6 library code, needed by static components when full IPv6 support is
+ * not configured or static.
+ */
+#include <net/ipv6.h>
+
+/* 
+ * find out if nexthdr is a well-known extension header or a protocol
+ */
+
+int ipv6_ext_hdr(u8 nexthdr)
+{
+	/* 
+	 * find out if nexthdr is an extension header or a protocol
+	 */
+	return ( (nexthdr == NEXTHDR_HOP)	||
+		 (nexthdr == NEXTHDR_ROUTING)	||
+		 (nexthdr == NEXTHDR_FRAGMENT)	||
+		 (nexthdr == NEXTHDR_AUTH)	||
+		 (nexthdr == NEXTHDR_NONE)	||
+		 (nexthdr == NEXTHDR_DEST) );
+}
+
+/*
+ * Skip any extension headers. This is used by the ICMP module.
+ *
+ * Note that strictly speaking this conflicts with RFC 2460 4.0:
+ * ...The contents and semantics of each extension header determine whether 
+ * or not to proceed to the next header.  Therefore, extension headers must
+ * be processed strictly in the order they appear in the packet; a
+ * receiver must not, for example, scan through a packet looking for a
+ * particular kind of extension header and process that header prior to
+ * processing all preceding ones.
+ * 
+ * We do exactly this. This is a protocol bug. We can't decide after a
+ * seeing an unknown discard-with-error flavour TLV option if it's a 
+ * ICMP error message or not (errors should never be send in reply to
+ * ICMP error messages).
+ * 
+ * But I see no other way to do this. This might need to be reexamined
+ * when Linux implements ESP (and maybe AUTH) headers.
+ * --AK
+ *
+ * This function parses (probably truncated) exthdr set "hdr"
+ * of length "len". "nexthdrp" initially points to some place,
+ * where type of the first header can be found.
+ *
+ * It skips all well-known exthdrs, and returns pointer to the start
+ * of unparsable area i.e. the first header with unknown type.
+ * If it is not NULL *nexthdr is updated by type/protocol of this header.
+ *
+ * NOTES: - if packet terminated with NEXTHDR_NONE it returns NULL.
+ *        - it may return pointer pointing beyond end of packet,
+ *	    if the last recognized header is truncated in the middle.
+ *        - if packet is truncated, so that all parsed headers are skipped,
+ *	    it returns NULL.
+ *	  - First fragment header is skipped, not-first ones
+ *	    are considered as unparsable.
+ *	  - ESP is unparsable for now and considered like
+ *	    normal payload protocol.
+ *	  - Note also special handling of AUTH header. Thanks to IPsec wizards.
+ *
+ * --ANK (980726)
+ */
+
+int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp, int len)
+{
+	u8 nexthdr = *nexthdrp;
+
+	while (ipv6_ext_hdr(nexthdr)) {
+		struct ipv6_opt_hdr hdr;
+		int hdrlen;
+
+		if (len < (int)sizeof(struct ipv6_opt_hdr))
+			return -1;
+		if (nexthdr == NEXTHDR_NONE)
+			return -1;
+		if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
+			BUG();
+		if (nexthdr == NEXTHDR_FRAGMENT) {
+			unsigned short frag_off;
+			if (skb_copy_bits(skb,
+					  start+offsetof(struct frag_hdr,
+							 frag_off),
+					  &frag_off,
+					  sizeof(frag_off))) {
+				return -1;
+			}
+
+			if (ntohs(frag_off) & ~0x7)
+				break;
+			hdrlen = 8;
+		} else if (nexthdr == NEXTHDR_AUTH)
+			hdrlen = (hdr.hdrlen+2)<<2; 
+		else
+			hdrlen = ipv6_optlen(&hdr); 
+
+		nexthdr = hdr.nexthdr;
+		len -= hdrlen;
+		start += hdrlen;
+	}
+
+	*nexthdrp = nexthdr;
+	return start;
+}
+
+EXPORT_SYMBOL(ipv6_ext_hdr);
+EXPORT_SYMBOL(ipv6_skip_exthdr);

net/ipv6/ipv6_syms.c

@@ -41,9 +41,7 @@ EXPORT_SYMBOL(xfrm6_rcv);
 #endif
 EXPORT_SYMBOL(rt6_lookup);
 EXPORT_SYMBOL(fl6_sock_lookup);
-EXPORT_SYMBOL(ipv6_ext_hdr);
 EXPORT_SYMBOL(ip6_append_data);
 EXPORT_SYMBOL(ip6_flush_pending_frames);
 EXPORT_SYMBOL(ip6_push_pending_frames);
 EXPORT_SYMBOL(ipv6_push_nfrag_opts);
-EXPORT_SYMBOL(ipv6_skip_exthdr);