ip6_tunnel - endianness annotations

Convert rel_info to host-endian before calling ip6_tnl_err().
The things become much more straightforward that way.
The key observation (and the reason why that code actually
worked) is that after ip6_tnl_err() we either immediately
bailed out or had rel_info set to 0 or had it set to host-endian
and guaranteed to hit
(rel_type == ICMP_DEST_UNREACH && rel_code == ICMP_FRAG_NEEDED)
case.  So inconsistent endianness didn't really lead to bugs,
but it had been subtle and prone to breakage.  New variant is
saner and obviously safe.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 9 deletions

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index df30976f6dfd..ca774d8e3be3 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -385,7 +385,7 @@ parse_tlv_tnl_enc_lim(struct sk_buff *skb, __u8 * raw)
 
 static int
 ip6_tnl_err(struct sk_buff *skb, __u8 ipproto, struct inet6_skb_parm *opt,
-            int *type, int *code, int *msg, __be32 *info, int offset)
+            int *type, int *code, int *msg, __u32 *info, int offset)
 {
         struct ipv6hdr *ipv6h = (struct ipv6hdr *) skb->data;
         struct ip6_tnl *t;
@@ -435,7 +435,7 @@ ip6_tnl_err(struct sk_buff *skb, __u8 ipproto, struct inet6_skb_parm *opt,
                 if ((*code) == ICMPV6_HDR_FIELD)
                         teli = parse_tlv_tnl_enc_lim(skb, skb->data);
 
-                if (teli && teli == ntohl(*info) - 2) {
+                if (teli && teli == *info - 2) {
                         tel = (struct ipv6_tlv_tnl_enc_lim *) &skb->data[teli];
                         if (tel->encap_limit == 0) {
                                 if (net_ratelimit())
@@ -452,7 +452,7 @@ ip6_tnl_err(struct sk_buff *skb, __u8 ipproto, struct inet6_skb_parm *opt,
                 }
                 break;
         case ICMPV6_PKT_TOOBIG:
-                mtu = ntohl(*info) - offset;
+                mtu = *info - offset;
                 if (mtu < IPV6_MIN_MTU)
                         mtu = IPV6_MIN_MTU;
                 t->dev->mtu = mtu;
@@ -478,12 +478,12 @@ out:
 
 static int
 ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
-           int type, int code, int offset, __u32 info)
+           int type, int code, int offset, __be32 info)
 {
         int rel_msg = 0;
         int rel_type = type;
         int rel_code = code;
-        __u32 rel_info = info;
+        __u32 rel_info = ntohl(info);
         int err;
         struct sk_buff *skb2;
         struct iphdr *eiph;
@@ -564,10 +564,9 @@ ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                         goto out;
 
                 skb2->dst->ops->update_pmtu(skb2->dst, rel_info);
-                rel_info = htonl(rel_info);
         }
 
-        icmp_send(skb2, rel_type, rel_code, rel_info);
+        icmp_send(skb2, rel_type, rel_code, htonl(rel_info));
 
 out:
         kfree_skb(skb2);
@@ -576,12 +575,12 @@ out:
 
 static int
 ip6ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
-           int type, int code, int offset, __u32 info)
+           int type, int code, int offset, __be32 info)
 {
         int rel_msg = 0;
         int rel_type = type;
         int rel_code = code;
-        __u32 rel_info = info;
+        __u32 rel_info = ntohl(info);
         int err;
 
         err = ip6_tnl_err(skb, IPPROTO_IPV6, opt, &rel_type, &rel_code,