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>

diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index c042ce19bd141f04982820b0b7375f5c0e148fad..86e28a75267f4dac4a72a4c02413ab6c99945a60 100644 (file)
--- 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);