lockd: create NSM handles per net namespace

Commit cb7323fffa85 ("lockd: create and use per-net NSM
 RPC clients on MON/UNMON requests") introduced per-net
NSM RPC clients. Unfortunately this doesn't make any sense
without per-net nsm_handle.

E.g. the following scenario could happen
Two hosts (X and Y) in different namespaces (A and B) share
the same nsm struct.

1. nsm_monitor(host_X) called => NSM rpc client created,
	nsm->sm_monitored bit set.
2. nsm_mointor(host-Y) called => nsm->sm_monitored already set,
	we just exit. Thus in namespace B ln->nsm_clnt == NULL.
3. host X destroyed => nsm->sm_count decremented to 1
4. host Y destroyed => nsm_unmonitor() => nsm_mon_unmon() => NULL-ptr
	dereference of *ln->nsm_clnt

So this could be fixed by making per-net nsm_handles list,
instead of global. Thus different net namespaces will not be able
share the same nsm_handle.

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index ff82a32871b5..fd3b65bf51b5 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -235,7 +235,8 @@ void		  nlm_rebind_host(struct nlm_host *);
 struct nlm_host * nlm_get_host(struct nlm_host *);
 void              nlm_shutdown_hosts(void);
 void              nlm_shutdown_hosts_net(struct net *net);
-void              nlm_host_rebooted(const struct nlm_reboot *);
+void              nlm_host_rebooted(const struct net *net,
+                                        const struct nlm_reboot *);
 
 /*
  * Host monitoring
@@ -243,11 +244,13 @@ void		  nlm_host_rebooted(const struct nlm_reboot *);
 int               nsm_monitor(const struct nlm_host *host);
 void              nsm_unmonitor(const struct nlm_host *host);
 
-struct nsm_handle *nsm_get_handle(const struct sockaddr *sap,
+struct nsm_handle *nsm_get_handle(const struct net *net,
+                                        const struct sockaddr *sap,
                                         const size_t salen,
                                         const char *hostname,
                                         const size_t hostname_len);
-struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info);
+struct nsm_handle *nsm_reboot_lookup(const struct net *net,
+                                        const struct nlm_reboot *info);
 void              nsm_release(struct nsm_handle *nsm);
 
 /*