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>

7 files changed, 36 insertions, 22 deletions

diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index 969d589c848d..b5f3c3ab0d5f 100644
--- a/fs/lockd/host.c
+++ b/fs/lockd/host.c
@@ -116,7 +116,7 @@ static struct nlm_host *nlm_alloc_host(struct nlm_lookup_host_info *ni,
                 atomic_inc(&nsm->sm_count);
         else {
                 host = NULL;
-                nsm = nsm_get_handle(ni->sap, ni->salen,
+                nsm = nsm_get_handle(ni->net, ni->sap, ni->salen,
                                         ni->hostname, ni->hostname_len);
                 if (unlikely(nsm == NULL)) {
                         dprintk("lockd: %s failed; no nsm handle\n",
@@ -534,17 +534,18 @@ static struct nlm_host *next_host_state(struct hlist_head *cache,
 
 /**
  * nlm_host_rebooted - Release all resources held by rebooted host
+ * @net:  network namespace
  * @info: pointer to decoded results of NLM_SM_NOTIFY call
  *
  * We were notified that the specified host has rebooted.  Release
  * all resources held by that peer.
  */
-void nlm_host_rebooted(const struct nlm_reboot *info)
+void nlm_host_rebooted(const struct net *net, const struct nlm_reboot *info)
 {
         struct nsm_handle *nsm;
         struct nlm_host *host;
 
-        nsm = nsm_reboot_lookup(info);
+        nsm = nsm_reboot_lookup(net, info);
         if (unlikely(nsm == NULL))
                 return;
 
diff --git a/fs/lockd/mon.c b/fs/lockd/mon.c
index 47a32b6d9b90..6c05cd17e520 100644
--- a/fs/lockd/mon.c
+++ b/fs/lockd/mon.c
@@ -51,7 +51,6 @@ struct nsm_res {
 };
 
 static const struct rpc_program nsm_program;
-static                          LIST_HEAD(nsm_handles);
 static                          DEFINE_SPINLOCK(nsm_lock);
 
 /*
@@ -264,33 +263,35 @@ void nsm_unmonitor(const struct nlm_host *host)
         }
 }
 
-static struct nsm_handle *nsm_lookup_hostname(const char *hostname,
-                                              const size_t len)
+static struct nsm_handle *nsm_lookup_hostname(const struct list_head *nsm_handles,
+                                        const char *hostname, const size_t len)
 {
         struct nsm_handle *nsm;
 
-        list_for_each_entry(nsm, &nsm_handles, sm_link)
+        list_for_each_entry(nsm, nsm_handles, sm_link)
                 if (strlen(nsm->sm_name) == len &&
                     memcmp(nsm->sm_name, hostname, len) == 0)
                         return nsm;
         return NULL;
 }
 
-static struct nsm_handle *nsm_lookup_addr(const struct sockaddr *sap)
+static struct nsm_handle *nsm_lookup_addr(const struct list_head *nsm_handles,
+                                        const struct sockaddr *sap)
 {
         struct nsm_handle *nsm;
 
-        list_for_each_entry(nsm, &nsm_handles, sm_link)
+        list_for_each_entry(nsm, nsm_handles, sm_link)
                 if (rpc_cmp_addr(nsm_addr(nsm), sap))
                         return nsm;
         return NULL;
 }
 
-static struct nsm_handle *nsm_lookup_priv(const struct nsm_private *priv)
+static struct nsm_handle *nsm_lookup_priv(const struct list_head *nsm_handles,
+                                        const struct nsm_private *priv)
 {
         struct nsm_handle *nsm;
 
-        list_for_each_entry(nsm, &nsm_handles, sm_link)
+        list_for_each_entry(nsm, nsm_handles, sm_link)
                 if (memcmp(nsm->sm_priv.data, priv->data,
                                         sizeof(priv->data)) == 0)
                         return nsm;
@@ -353,6 +354,7 @@ static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
 
 /**
  * nsm_get_handle - Find or create a cached nsm_handle
+ * @net: network namespace
  * @sap: pointer to socket address of handle to find
  * @salen: length of socket address
  * @hostname: pointer to C string containing hostname to find
@@ -365,11 +367,13 @@ static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
  * @hostname cannot be found in the handle cache.  Returns NULL if
  * an error occurs.
  */
-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 *cached, *new = NULL;
+        struct lockd_net *ln = net_generic(net, lockd_net_id);
 
         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
                 if (printk_ratelimit()) {
@@ -384,9 +388,10 @@ retry:
         spin_lock(&nsm_lock);
 
         if (nsm_use_hostnames && hostname != NULL)
-                cached = nsm_lookup_hostname(hostname, hostname_len);
+                cached = nsm_lookup_hostname(&ln->nsm_handles,
+                                        hostname, hostname_len);
         else
-                cached = nsm_lookup_addr(sap);
+                cached = nsm_lookup_addr(&ln->nsm_handles, sap);
 
         if (cached != NULL) {
                 atomic_inc(&cached->sm_count);
@@ -400,7 +405,7 @@ retry:
         }
 
         if (new != NULL) {
-                list_add(&new->sm_link, &nsm_handles);
+                list_add(&new->sm_link, &ln->nsm_handles);
                 spin_unlock(&nsm_lock);
                 dprintk("lockd: created nsm_handle for %s (%s)\n",
                                 new->sm_name, new->sm_addrbuf);
@@ -417,19 +422,22 @@ retry:
 
 /**
  * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
+ * @net:  network namespace
  * @info: pointer to NLMPROC_SM_NOTIFY arguments
  *
  * Returns a matching nsm_handle if found in the nsm cache. The returned
  * nsm_handle's reference count is bumped. Otherwise returns NULL if some
  * error occurred.
  */
-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)
 {
         struct nsm_handle *cached;
+        struct lockd_net *ln = net_generic(net, lockd_net_id);
 
         spin_lock(&nsm_lock);
 
-        cached = nsm_lookup_priv(&info->priv);
+        cached = nsm_lookup_priv(&ln->nsm_handles, &info->priv);
         if (unlikely(cached == NULL)) {
                 spin_unlock(&nsm_lock);
                 dprintk("lockd: never saw rebooted peer '%.*s' before\n",
diff --git a/fs/lockd/netns.h b/fs/lockd/netns.h
index 097bfa3adb1c..89fe011b1335 100644
--- a/fs/lockd/netns.h
+++ b/fs/lockd/netns.h
@@ -15,6 +15,7 @@ struct lockd_net {
         spinlock_t nsm_clnt_lock;
         unsigned int nsm_users;
         struct rpc_clnt *nsm_clnt;
+        struct list_head nsm_handles;
 };
 
 extern int lockd_net_id;
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index d678bcc3cbcb..0dff13f41808 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -593,6 +593,7 @@ static int lockd_init_net(struct net *net)
         INIT_LIST_HEAD(&ln->lockd_manager.list);
         ln->lockd_manager.block_opens = false;
         spin_lock_init(&ln->nsm_clnt_lock);
+        INIT_LIST_HEAD(&ln->nsm_handles);
         return 0;
 }
 
diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index b147d1ae71fd..09c576f26c7b 100644
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -421,7 +421,7 @@ nlm4svc_proc_sm_notify(struct svc_rqst *rqstp, struct nlm_reboot *argp,
                 return rpc_system_err;
         }
 
-        nlm_host_rebooted(argp);
+        nlm_host_rebooted(SVC_NET(rqstp), argp);
         return rpc_success;
 }
 
diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
index 21171f0c6477..fb26b9f522e7 100644
--- a/fs/lockd/svcproc.c
+++ b/fs/lockd/svcproc.c
@@ -464,7 +464,7 @@ nlmsvc_proc_sm_notify(struct svc_rqst *rqstp, struct nlm_reboot *argp,
                 return rpc_system_err;
         }
 
-        nlm_host_rebooted(argp);
+        nlm_host_rebooted(SVC_NET(rqstp), argp);
         return rpc_success;
 }
 
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);
 
 /*