firmware_class: perform new LSM checks

This attaches LSM hooks to the existing firmware loading interfaces:
filesystem-found firmware and demand-loaded blobs. On errors, loads
are aborted and the failure code is returned to userspace.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index d276e33..63f165c 100644 (file)
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -28,6 +28,7 @@
 #include <linux/suspend.h>
 #include <linux/syscore_ops.h>
 #include <linux/reboot.h>
+#include <linux/security.h>
 
 #include <generated/utsrelease.h>
 
@@ -308,12 +309,17 @@ static int fw_read_file_contents(struct file *file, struct firmware_buf *fw_buf)
        if (rc != size) {
                if (rc > 0)
                        rc = -EIO;
-               vfree(buf);
-               return rc;
+               goto fail;
        }
+       rc = security_kernel_fw_from_file(file, buf, size);
+       if (rc)
+               goto fail;
        fw_buf->data = buf;
        fw_buf->size = size;
        return 0;
+fail:
+       vfree(buf);
+       return rc;
 }
 
 static int fw_get_filesystem_firmware(struct device *device,
@@ -617,6 +623,7 @@ static ssize_t firmware_loading_store(struct device *dev,
 {
        struct firmware_priv *fw_priv = to_firmware_priv(dev);
        struct firmware_buf *fw_buf;
+       ssize_t written = count;
        int loading = simple_strtol(buf, NULL, 10);
        int i;
 
@@ -640,6 +647,8 @@ static ssize_t firmware_loading_store(struct device *dev,
                break;
        case 0:
                if (test_bit(FW_STATUS_LOADING, &fw_buf->status)) {
+                       int rc;
+
                        set_bit(FW_STATUS_DONE, &fw_buf->status);
                        clear_bit(FW_STATUS_LOADING, &fw_buf->status);
 
@@ -649,10 +658,23 @@ static ssize_t firmware_loading_store(struct device *dev,
                         * see the mapped 'buf->data' once the loading
                         * is completed.
                         * */
-                       if (fw_map_pages_buf(fw_buf))
+                       rc = fw_map_pages_buf(fw_buf);
+                       if (rc)
                                dev_err(dev, "%s: map pages failed\n",
                                        __func__);
+                       else
+                               rc = security_kernel_fw_from_file(NULL,
+                                               fw_buf->data, fw_buf->size);
+
+                       /*
+                        * Same logic as fw_load_abort, only the DONE bit
+                        * is ignored and we set ABORT only on failure.
+                        */
                        list_del_init(&fw_buf->pending_list);
+                       if (rc) {
+                               set_bit(FW_STATUS_ABORT, &fw_buf->status);
+                               written = rc;
+                       }
                        complete_all(&fw_buf->completion);
                        break;
                }
@@ -666,7 +688,7 @@ static ssize_t firmware_loading_store(struct device *dev,
        }
 out:
        mutex_unlock(&fw_lock);
-       return count;
+       return written;
 }
 
 static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);