lwtunnel: fix autoload of lwt modules
Trying to add an mpls encap route when the MPLS modules are not loaded
hangs. For example:
CONFIG_MPLS=y
CONFIG_NET_MPLS_GSO=m
CONFIG_MPLS_ROUTING=m
CONFIG_MPLS_IPTUNNEL=m
$ ip route add 10.10.10.10/32 encap mpls 100 via inet 10.100.1.2
The ip command hangs:
root 880 826 0 21:25 pts/0 00:00:00 ip route add 10.10.10.10/32 encap mpls 100 via inet 10.100.1.2
$ cat /proc/880/stack
[<ffffffff81065a9b>] call_usermodehelper_exec+0xd6/0x134
[<ffffffff81065efc>] __request_module+0x27b/0x30a
[<ffffffff814542f6>] lwtunnel_build_state+0xe4/0x178
[<ffffffff814aa1e4>] fib_create_info+0x47f/0xdd4
[<ffffffff814ae451>] fib_table_insert+0x90/0x41f
[<ffffffff814a8010>] inet_rtm_newroute+0x4b/0x52
...
modprobe is trying to load rtnl-lwt-MPLS:
root 881 5 0 21:25 ? 00:00:00 /sbin/modprobe -q -- rtnl-lwt-MPLS
and it hangs after loading mpls_router:
$ cat /proc/881/stack
[<ffffffff81441537>] rtnl_lock+0x12/0x14
[<ffffffff8142ca2a>] register_netdevice_notifier+0x16/0x179
[<ffffffffa0033025>] mpls_init+0x25/0x1000 [mpls_router]
[<ffffffff81000471>] do_one_initcall+0x8e/0x13f
[<ffffffff81119961>] do_init_module+0x5a/0x1e5
[<ffffffff810bd070>] load_module+0x13bd/0x17d6
...
The problem is that lwtunnel_build_state is called with rtnl lock
held preventing mpls_init from registering.
Given the potential references held by the time lwtunnel_build_state it
can not drop the rtnl lock to the load module. So, extract the module
loading code from lwtunnel_build_state into a new function to validate
the encap type. The new function is called while converting the user
request into a fib_config which is well before any table, device or
fib entries are examined.
Fixes: 745041e2aaf1 ("lwtunnel: autoload of lwt modules")
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index eae0332..7db2ad2 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -46,6 +46,7 @@
#include <net/rtnetlink.h>
#include <net/xfrm.h>
#include <net/l3mdev.h>
+#include <net/lwtunnel.h>
#include <trace/events/fib.h>
#ifndef CONFIG_IP_MULTIPLE_TABLES
@@ -677,6 +678,10 @@
cfg->fc_mx_len = nla_len(attr);
break;
case RTA_MULTIPATH:
+ err = lwtunnel_valid_encap_type_attr(nla_data(attr),
+ nla_len(attr));
+ if (err < 0)
+ goto errout;
cfg->fc_mp = nla_data(attr);
cfg->fc_mp_len = nla_len(attr);
break;
@@ -691,6 +696,9 @@
break;
case RTA_ENCAP_TYPE:
cfg->fc_encap_type = nla_get_u16(attr);
+ err = lwtunnel_valid_encap_type(cfg->fc_encap_type);
+ if (err < 0)
+ goto errout;
break;
}
}