NFSv4: Ensure that idmap_pipe_downcall sanity-checks the downcall data

Use the idmapper upcall data to verify that the legacy idmapper daemon
is indeed responding to an upcall that we sent.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Bryan Schumaker <bjschuma@netapp.com>

1 files changed, 37 insertions, 25 deletions

diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index 8222ad861456..7ac93e0dd4cf 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -55,18 +55,19 @@
 static const struct cred *id_resolver_cache;
 static struct key_type key_type_id_resolver_legacy;
 
-struct idmap {
-        struct rpc_pipe         *idmap_pipe;
-        struct key_construction *idmap_key_cons;
-        struct mutex            idmap_mutex;
-};
-
 struct idmap_legacy_upcalldata {
         struct rpc_pipe_msg pipe_msg;
         struct idmap_msg idmap_msg;
+        struct key_construction *key_cons;
         struct idmap *idmap;
 };
 
+struct idmap {
+        struct rpc_pipe         *idmap_pipe;
+        struct idmap_legacy_upcalldata *idmap_upcall_data;
+        struct mutex            idmap_mutex;
+};
+
 /**
  * nfs_fattr_init_names - initialise the nfs_fattr owner_name/group_name fields
  * @fattr: fully initialised struct nfs_fattr
@@ -663,29 +664,30 @@ out:
 
 static bool
 nfs_idmap_prepare_pipe_upcall(struct idmap *idmap,
-                struct key_construction *cons)
+                struct idmap_legacy_upcalldata *data)
 {
-        if (idmap->idmap_key_cons != NULL) {
+        if (idmap->idmap_upcall_data != NULL) {
                 WARN_ON_ONCE(1);
                 return false;
         }
-        idmap->idmap_key_cons = cons;
+        idmap->idmap_upcall_data = data;
         return true;
 }
 
 static void
 nfs_idmap_complete_pipe_upcall_locked(struct idmap *idmap, int ret)
 {
-        struct key_construction *cons = idmap->idmap_key_cons;
+        struct key_construction *cons = idmap->idmap_upcall_data->key_cons;
 
-        idmap->idmap_key_cons = NULL;
+        kfree(idmap->idmap_upcall_data);
+        idmap->idmap_upcall_data = NULL;
         complete_request_key(cons, ret);
 }
 
 static void
 nfs_idmap_abort_pipe_upcall(struct idmap *idmap, int ret)
 {
-        if (idmap->idmap_key_cons != NULL)
+        if (idmap->idmap_upcall_data != NULL)
                 nfs_idmap_complete_pipe_upcall_locked(idmap, ret);
 }
 
@@ -714,14 +716,12 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,
                 goto out2;
 
         ret = -EAGAIN;
-        if (!nfs_idmap_prepare_pipe_upcall(idmap, cons))
+        if (!nfs_idmap_prepare_pipe_upcall(idmap, data))
                 goto out2;
 
         ret = rpc_queue_upcall(idmap->idmap_pipe, msg);
-        if (ret < 0) {
+        if (ret < 0)
                 nfs_idmap_abort_pipe_upcall(idmap, ret);
-                kfree(data);
-        }
 
         return ret;
 out2:
@@ -738,21 +738,32 @@ static int nfs_idmap_instantiate(struct key *key, struct key *authkey, char *dat
                                         authkey);
 }
 
-static int nfs_idmap_read_message(struct idmap_msg *im, struct key *key, struct key *authkey)
+static int nfs_idmap_read_and_verify_message(struct idmap_msg *im,
+                struct idmap_msg *upcall,
+                struct key *key, struct key *authkey)
 {
         char id_str[NFS_UINT_MAXLEN];
-        int ret = -EINVAL;
+        int ret = -ENOKEY;
 
+        /* ret = -ENOKEY */
+        if (upcall->im_type != im->im_type || upcall->im_conv != im->im_conv)
+                goto out;
         switch (im->im_conv) {
         case IDMAP_CONV_NAMETOID:
+                if (strcmp(upcall->im_name, im->im_name) != 0)
+                        break;
                 sprintf(id_str, "%d", im->im_id);
                 ret = nfs_idmap_instantiate(key, authkey, id_str);
                 break;
         case IDMAP_CONV_IDTONAME:
+                if (upcall->im_id != im->im_id)
+                        break;
                 ret = nfs_idmap_instantiate(key, authkey, im->im_name);
                 break;
+        default:
+                ret = -EINVAL;
         }
-
+out:
         return ret;
 }
 
@@ -770,10 +781,11 @@ idmap_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
          * will have been woken up and someone else may now have used
          * idmap_key_cons - so after this point we may no longer touch it.
          */
-        cons = idmap->idmap_key_cons;
-        if (cons == NULL)
+        if (idmap->idmap_upcall_data == NULL)
                 goto out_noupcall;
 
+        cons = idmap->idmap_upcall_data->key_cons;
+
         if (mlen != sizeof(im)) {
                 ret = -ENOSPC;
                 goto out;
@@ -793,9 +805,11 @@ idmap_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
         if (namelen_in == 0 || namelen_in == IDMAP_NAMESZ) {
                 ret = -EINVAL;
                 goto out;
-        }
+}
 
-        ret = nfs_idmap_read_message(&im, cons->key, cons->authkey);
+        ret = nfs_idmap_read_and_verify_message(&im,
+                        &idmap->idmap_upcall_data->idmap_msg,
+                        cons->key, cons->authkey);
         if (ret >= 0) {
                 key_set_timeout(cons->key, nfs_idmap_cache_timeout);
                 ret = mlen;
@@ -817,8 +831,6 @@ idmap_pipe_destroy_msg(struct rpc_pipe_msg *msg)
 
         if (msg->errno)
                 nfs_idmap_abort_pipe_upcall(idmap, msg->errno);
-        /* Free memory allocated in nfs_idmap_legacy_upcall() */
-        kfree(data);
 }
 
 static void