Re: [Xen-devel] [PATCH] xl: Perform minimal validation of virtual disk file while parsing config file

[Kamala Narasimhan <kamala.narasimhan@xxxxxxxxx>]

> I will make necessary changes and resend the patch.
>

Here is a modified patch for further review and to apply if ok.

Signed-off-by: Kamala Narasimhan <kamala.narasimhan@xxxxxxxxxx>

diff -r fe8a177ae9cb tools/libxl/libxl.c
--- a/tools/libxl/libxl.c       Wed Jan 19 15:29:04 2011 +0000
+++ b/tools/libxl/libxl.c       Wed Jan 19 12:41:11 2011 -0500
@@ -826,6 +826,41 @@ skip_autopass:

 
/******************************************************************************/

+static int validate_virtual_disk(char *file_name, libxl_disk_phystype
disk_type)
+{
+    struct stat stat_buf;
+
+    if ( file_name == NULL ) {
+        fprintf(stderr, "Virtual disk file name is NULL!\n");
+        return 0;
+    }
+
+    /* Return without further validation for empty cdrom drive.
+       Note: Post 4.1 we need to change the interface to handle empty
+       cdrom rather than go with the below assumption.
+     */
+    if ( (strncmp(file_name, "", sizeof("")) == 0) && (disk_type ==
PHYSTYPE_PHY) )
+        return 1;
+
+    if ( stat(file_name, &stat_buf) != 0 ) {
+        fprintf(stderr, "Stat on virtual disk %s returned error - \"%s\".\n",
+            file_name, strerror(errno));
+        return 0;
+    }
+    if ( disk_type == PHYSTYPE_PHY ) {
+        if ( !(S_ISBLK(stat_buf.st_mode)) ) {
+            fprintf(stderr, "Virtual disk %s is not a block device!\n",
+                file_name);
+            return 0;
+        }
+    }else if ( stat_buf.st_size == 0 ) {
+        fprintf(stderr, "Virtual disk %s size is 0!\n", file_name);
+        return 0;
+    }
+
+    return 1;
+}
+
 int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid,
libxl_device_disk *disk)
 {
     libxl__gc gc = LIBXL_INIT_GC(ctx);
@@ -835,6 +870,9 @@ int libxl_device_disk_add(libxl_ctx *ctx
     int devid;
     libxl__device device;
     int major, minor, rc;
+
+    if ( validate_virtual_disk(disk->physpath, disk->phystype) == 0 )
+        return ERROR_FAIL;

     front = flexarray_make(16, 1);
     if (!front) {

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