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Message-Id: <1484693856-26021-1-git-send-email-dsa@cumulusnetworks.com>
Date: Tue, 17 Jan 2017 14:57:36 -0800
From: David Ahern <dsa@...ulusnetworks.com>
To: netdev@...r.kernel.org
Cc: rshearma@...cade.com, David Ahern <dsa@...ulusnetworks.com>
Subject: [PATCH net v2] 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@...ulusnetworks.com>
---
v2
- extract the module load attempt into a separate function that is
called early in the newroute code paths
include/net/lwtunnel.h | 11 +++++++++
net/core/lwtunnel.c | 62 ++++++++++++++++++++++++++++++++++++++++++++-----
net/ipv4/fib_frontend.c | 8 +++++++
net/ipv6/route.c | 12 +++++++++-
4 files changed, 86 insertions(+), 7 deletions(-)
diff --git a/include/net/lwtunnel.h b/include/net/lwtunnel.h
index d4c1c75b8862..0b585f1fd340 100644
--- a/include/net/lwtunnel.h
+++ b/include/net/lwtunnel.h
@@ -105,6 +105,8 @@ int lwtunnel_encap_add_ops(const struct lwtunnel_encap_ops *op,
unsigned int num);
int lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops *op,
unsigned int num);
+int lwtunnel_valid_encap_type(u16 encap_type);
+int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int len);
int lwtunnel_build_state(struct net_device *dev, u16 encap_type,
struct nlattr *encap,
unsigned int family, const void *cfg,
@@ -168,6 +170,15 @@ static inline int lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops *op,
return -EOPNOTSUPP;
}
+static inline int lwtunnel_valid_encap_type(u16 encap_type)
+{
+ return -EOPNOTSUPP;
+}
+static inline int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int len)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int lwtunnel_build_state(struct net_device *dev, u16 encap_type,
struct nlattr *encap,
unsigned int family, const void *cfg,
diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
index a5d4e866ce88..47b1dd65947b 100644
--- a/net/core/lwtunnel.c
+++ b/net/core/lwtunnel.c
@@ -26,6 +26,7 @@
#include <net/lwtunnel.h>
#include <net/rtnetlink.h>
#include <net/ip6_fib.h>
+#include <net/nexthop.h>
#ifdef CONFIG_MODULES
@@ -114,25 +115,74 @@ int lwtunnel_build_state(struct net_device *dev, u16 encap_type,
ret = -EOPNOTSUPP;
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[encap_type]);
+ if (likely(ops && ops->build_state))
+ ret = ops->build_state(dev, encap, family, cfg, lws);
+ rcu_read_unlock();
+
+ return ret;
+}
+EXPORT_SYMBOL(lwtunnel_build_state);
+
+int lwtunnel_valid_encap_type(u16 encap_type)
+{
+ const struct lwtunnel_encap_ops *ops;
+ int ret = -EINVAL;
+
+ if (encap_type == LWTUNNEL_ENCAP_NONE ||
+ encap_type > LWTUNNEL_ENCAP_MAX)
+ return ret;
+
+ rcu_read_lock();
+ ops = rcu_dereference(lwtun_encaps[encap_type]);
+ rcu_read_unlock();
#ifdef CONFIG_MODULES
if (!ops) {
const char *encap_type_str = lwtunnel_encap_str(encap_type);
if (encap_type_str) {
- rcu_read_unlock();
+ __rtnl_unlock();
request_module("rtnl-lwt-%s", encap_type_str);
+ rtnl_lock();
+
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[encap_type]);
+ rcu_read_unlock();
}
}
#endif
- if (likely(ops && ops->build_state))
- ret = ops->build_state(dev, encap, family, cfg, lws);
- rcu_read_unlock();
+ return ops ? 0 : -EOPNOTSUPP;
+}
+EXPORT_SYMBOL(lwtunnel_valid_encap_type);
- return ret;
+int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int remaining)
+{
+ struct rtnexthop *rtnh = (struct rtnexthop *)attr;
+ struct nlattr *nla_entype;
+ struct nlattr *attrs;
+ struct nlattr *nla;
+ u16 encap_type;
+ int attrlen;
+
+ while (rtnh_ok(rtnh, remaining)) {
+ attrlen = rtnh_attrlen(rtnh);
+ if (attrlen > 0) {
+ attrs = rtnh_attrs(rtnh);
+ nla = nla_find(attrs, attrlen, RTA_ENCAP);
+ nla_entype = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
+
+ if (nla_entype) {
+ encap_type = nla_get_u16(nla_entype);
+
+ if (lwtunnel_valid_encap_type(encap_type) != 0)
+ return -EOPNOTSUPP;
+ }
+ }
+ rtnh = rtnh_next(rtnh, &remaining);
+ }
+
+ return 0;
}
-EXPORT_SYMBOL(lwtunnel_build_state);
+EXPORT_SYMBOL(lwtunnel_valid_encap_type_attr);
void lwtstate_free(struct lwtunnel_state *lws)
{
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index eae0332b0e8c..7db2ad2e82d3 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 @@ static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,
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 @@ static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,
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;
}
}
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 4f6b067c8753..7ea85370c11c 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2896,6 +2896,11 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
if (tb[RTA_MULTIPATH]) {
cfg->fc_mp = nla_data(tb[RTA_MULTIPATH]);
cfg->fc_mp_len = nla_len(tb[RTA_MULTIPATH]);
+
+ err = lwtunnel_valid_encap_type_attr(cfg->fc_mp,
+ cfg->fc_mp_len);
+ if (err < 0)
+ goto errout;
}
if (tb[RTA_PREF]) {
@@ -2909,9 +2914,14 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
if (tb[RTA_ENCAP])
cfg->fc_encap = tb[RTA_ENCAP];
- if (tb[RTA_ENCAP_TYPE])
+ if (tb[RTA_ENCAP_TYPE]) {
cfg->fc_encap_type = nla_get_u16(tb[RTA_ENCAP_TYPE]);
+ err = lwtunnel_valid_encap_type(cfg->fc_encap_type);
+ if (err < 0)
+ goto errout;
+ }
+
if (tb[RTA_EXPIRES]) {
unsigned long timeout = addrconf_timeout_fixup(nla_get_u32(tb[RTA_EXPIRES]), HZ);
--
2.1.4
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