Description of problem:

The ip command fails to assign a default IPv6 route from command line, but the same route configured through the configuration file (ifcfg-eth0) works well on starting (or restarting) the service network.

Version-Release number of selected component (if applicable):
iproute-2.6.32-32.el6_5 and previous

How reproducible:


Steps to Reproduce:
1. Enable the IPv6 on a NIC assign the IPv6 address 'fdde::1/128'

# cat /etc/sysconfig/network-scripts/ifcfg-eth0 
DEVICE="eth0"
BOOTPROTO="dhcp"
HWADDR="52:54:00:16:8F:13"
IPV6INIT="yes"
NM_CONTROLLED="yes"
ONBOOT="yes"
TYPE="Ethernet"
UUID="65882a64-4ca8-423b-b8af-64dd50b4550b"
IPV6ADDR=fdde::1/128

2. Restart the network

service network restart

3. Show the current IPv6 routes to eth0 NIC:

# ip -6 route show dev eth0
fdde::1  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295

4. Execute the command to configure the default route:

# /sbin/ip -6 route add default via fdde::1 metric 1

Actual results:

The command returns the message:

RTNETLINK answers: Invalid argument

And the error code '2'.

Executing the command to show routes again it shows the same list:

# ip -6 route show dev eth0
fdde::1  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295


Expected results:

The command should be executed without to show error message and the error code should be '0'.

Executing the command to show route should contains the default route on list:

# ip -6 route show dev eth0
fdde::1  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
default via fdde::1  metric 1  mtu 1500 advmss 1440 hoplimit 4294967295


Additional info:

If the route is added to 'ifcfg-eth0' file:

# cat /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE="eth0"
BOOTPROTO="dhcp"
HWADDR="52:54:00:16:8F:13"
IPV6INIT="yes"
NM_CONTROLLED="yes"
ONBOOT="yes"
TYPE="Ethernet"
UUID="65882a64-4ca8-423b-b8af-64dd50b4550b"
IPV6ADDR=fdde::1/128
IPV6_DEFAULTGW=fdde::1

And the network restarted:

# service network restart
Shutting down interface eth0:                              [  OK  ]
Shutting down loopback interface:                          [  OK  ]
Bringing up loopback interface:                            [  OK  ]
Bringing up interface eth0:  
Determining IP information for eth0... done.
                                                           [  OK  ]

The default route is configured successfully:

 # ip -6 route show dev eth0
fdde::1  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
default via fdde::1  metric 1  mtu 1500 advmss 1440 hoplimit 4294967295

I debugged the 'network-functions-ipv6' script and the route is assigned using the same commando that is used by command line:

/sbin/ip -6 route add default via fdde::1 metric 1

The error message came from the function 'rtnl_talk' on source file 'iproute2-2.6.31/lib/libnetlink.c':

295 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
296           unsigned groups, struct nlmsghdr *answer,
297           rtnl_filter_t junk,
298           void *jarg)
299 {
...
337     while (1) {
338         iov.iov_len = sizeof(buf);
339         status = recvmsg(rtnl->fd, &msg, 0);
...
384             if (h->nlmsg_type == NLMSG_ERROR) {
385                 struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
386                 if (l < sizeof(struct nlmsgerr)) {
387                     fprintf(stderr, "ERROR truncated\n");
388                 } else {
389                     errno = -err->error;
390                     if (errno == 0) {
391                         if (answer)
392                             memcpy(answer, h, h->nlmsg_len);
393                         return 0;
394                     }
395                     perror("RTNETLINK answers");   <------------------
...

The function 'rtnl_talk' is called from 'iproute_modify':

 667 int iproute_modify(int cmd, unsigned flags, int argc, char **argv)
 668 {
...
 995     if (rtnl_talk(&rth, &req.n, 0, 0, NULL, NULL, NULL) < 0)
 996         exit(2);
 997 
 998     return 0;
 999 }