NFS: Clear key construction data if the idmap upcall fails

idmap_pipe_downcall already clears this field if the upcall succeeds,
but if it fails (rpc.idmapd isn't running) the field will still be set
on the next call triggering a BUG_ON().  This patch tries to handle all
possible ways that the upcall could fail and clear the idmap key data
for each one.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Tested-by: William Dauchy <wdauchy@gmail.com>
Cc: stable@vger.kernel.org [>= 3.4]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 42 insertions, 14 deletions

diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index b701358c39c3..6703c73307a5 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -61,6 +61,12 @@ struct idmap {
         struct mutex            idmap_mutex;
 };
 
+struct idmap_legacy_upcalldata {
+        struct rpc_pipe_msg pipe_msg;
+        struct idmap_msg idmap_msg;
+        struct idmap *idmap;
+};
+
 /**
  * nfs_fattr_init_names - initialise the nfs_fattr owner_name/group_name fields
  * @fattr: fully initialised struct nfs_fattr
@@ -324,6 +330,7 @@ static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
                 ret = nfs_idmap_request_key(&key_type_id_resolver_legacy,
                                             name, namelen, type, data,
                                             data_size, idmap);
+                idmap->idmap_key_cons = NULL;
                 mutex_unlock(&idmap->idmap_mutex);
         }
         return ret;
@@ -380,11 +387,13 @@ static const match_table_t nfs_idmap_tokens = {
 static int nfs_idmap_legacy_upcall(struct key_construction *, const char *, void *);
 static ssize_t idmap_pipe_downcall(struct file *, const char __user *,
                                    size_t);
+static void idmap_release_pipe(struct inode *);
 static void idmap_pipe_destroy_msg(struct rpc_pipe_msg *);
 
 static const struct rpc_pipe_ops idmap_upcall_ops = {
         .upcall         = rpc_pipe_generic_upcall,
         .downcall       = idmap_pipe_downcall,
+        .release_pipe   = idmap_release_pipe,
         .destroy_msg    = idmap_pipe_destroy_msg,
 };
 
@@ -616,7 +625,8 @@ void nfs_idmap_quit(void)
         nfs_idmap_quit_keyring();
 }
 
-static int nfs_idmap_prepare_message(char *desc, struct idmap_msg *im,
+static int nfs_idmap_prepare_message(char *desc, struct idmap *idmap,
+                                     struct idmap_msg *im,
                                      struct rpc_pipe_msg *msg)
 {
         substring_t substr;
@@ -659,6 +669,7 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,
                                    const char *op,
                                    void *aux)
 {
+        struct idmap_legacy_upcalldata *data;
         struct rpc_pipe_msg *msg;
         struct idmap_msg *im;
         struct idmap *idmap = (struct idmap *)aux;
@@ -666,15 +677,15 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,
         int ret = -ENOMEM;
 
         /* msg and im are freed in idmap_pipe_destroy_msg */
-        msg = kmalloc(sizeof(*msg), GFP_KERNEL);
-        if (!msg)
-                goto out0;
-
-        im = kmalloc(sizeof(*im), GFP_KERNEL);
-        if (!im)
+        data = kmalloc(sizeof(*data), GFP_KERNEL);
+        if (!data)
                 goto out1;
 
-        ret = nfs_idmap_prepare_message(key->description, im, msg);
+        msg = &data->pipe_msg;
+        im = &data->idmap_msg;
+        data->idmap = idmap;
+
+        ret = nfs_idmap_prepare_message(key->description, idmap, im, msg);
         if (ret < 0)
                 goto out2;
 
@@ -683,15 +694,15 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,
 
         ret = rpc_queue_upcall(idmap->idmap_pipe, msg);
         if (ret < 0)
-                goto out2;
+                goto out3;
 
         return ret;
 
+out3:
+        idmap->idmap_key_cons = NULL;
 out2:
-        kfree(im);
+        kfree(data);
 out1:
-        kfree(msg);
-out0:
         complete_request_key(cons, ret);
         return ret;
 }
@@ -775,9 +786,26 @@ out_incomplete:
 static void
 idmap_pipe_destroy_msg(struct rpc_pipe_msg *msg)
 {
+        struct idmap_legacy_upcalldata *data = container_of(msg,
+                        struct idmap_legacy_upcalldata,
+                        pipe_msg);
+        struct idmap *idmap = data->idmap;
+        struct key_construction *cons;
+        if (msg->errno) {
+                cons = ACCESS_ONCE(idmap->idmap_key_cons);
+                idmap->idmap_key_cons = NULL;
+                complete_request_key(cons, msg->errno);
+        }
         /* Free memory allocated in nfs_idmap_legacy_upcall() */
-        kfree(msg->data);
-        kfree(msg);
+        kfree(data);
+}
+
+static void
+idmap_release_pipe(struct inode *inode)
+{
+        struct rpc_inode *rpci = RPC_I(inode);
+        struct idmap *idmap = (struct idmap *)rpci->private;
+        idmap->idmap_key_cons = NULL;
 }
 
 int nfs_map_name_to_uid(const struct nfs_server *server, const char *name, size_t namelen, __u32 *uid)