ipv6: Remove options header when setsockopt's optlen is 0

Remove the sticky Hop-by-Hop options header by calling setsockopt()
for IPV6_HOPOPTS with a zero option length, per RFC3542.

Routing header and Destination options header does the same as
Hop-by-Hop options header.

Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 4 deletions

diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index c042ce19bd14..86e28a75267f 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -345,18 +345,21 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
         case IPV6_DSTOPTS:
         {
                 struct ipv6_txoptions *opt;
+
+                /* remove any sticky options header with a zero option
+                 * length, per RFC3542.
+                 */
                 if (optlen == 0)
                         optval = NULL;
+                else if (optlen < sizeof(struct ipv6_opt_hdr) ||
+                         optlen & 0x7 || optlen > 8 * 255)
+                        goto e_inval;
 
                 /* hop-by-hop / destination options are privileged option */
                 retv = -EPERM;
                 if (optname != IPV6_RTHDR && !capable(CAP_NET_RAW))
                         break;
 
-                if (optlen < sizeof(struct ipv6_opt_hdr) ||
-                    optlen & 0x7 || optlen > 8 * 255)
-                        goto e_inval;
-
                 opt = ipv6_renew_options(sk, np->opt, optname,
                                          (struct ipv6_opt_hdr __user *)optval,
                                          optlen);