[IB] uverbs: Add a mask of device methods allowed for userspace

Give each device a uverbs_cmd_mask, so that a low-level driver can
control which methods may be called on behalf of userspace.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/core/uverbs_main.c

@@ -514,7 +514,8 @@ static ssize_t ib_uverbs_write(struct file *filp, const char __user *buf,
 
 	if (hdr.command < 0				||
 	    hdr.command >= ARRAY_SIZE(uverbs_cmd_table) ||
-	    !uverbs_cmd_table[hdr.command])
+	    !uverbs_cmd_table[hdr.command]		||
+	    !(file->device->ib_dev->uverbs_cmd_mask & (1ull << hdr.command)))
 		return -EINVAL;
 
 	if (!file->ucontext &&