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

[Kamala Narasimhan <kamala.narasimhan@xxxxxxxxx>]

Ian - Apologies for the delay.  I think I have covered all comments so far.  If 
there are more I will get to it ASAP.  Please let me know.

Also, I switched email client to avoid word wrapping and other issues.  If you 
still find the format of the patches inconvenient, please let me know.

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

Kamala


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       Fri Jan 21 18:00:37 2011 -0500
@@ -826,6 +826,35 @@ skip_autopass:

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

+static int validate_virtual_disk(libxl_ctx *ctx, char *file_name, 
libxl_disk_phystype disk_type)
+{
+    struct stat stat_buf;
+
+    /* 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 ( (file_name[0] == '\0') && (disk_type == PHYSTYPE_PHY) )
+        return 0;
+
+    if ( stat(file_name, &stat_buf) != 0 ) {
+        LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "failed to stat %s", 
file_name);
+        return ERROR_INVAL;
+    }
+    if ( disk_type == PHYSTYPE_PHY ) {
+        if ( !(S_ISBLK(stat_buf.st_mode)) ) {
+            LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "Virtual disk %s is not a block 
device!\n",
+                file_name);
+            return ERROR_INVAL;
+        }
+    } else if ( stat_buf.st_size == 0 ) {
+        LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "Virtual disk %s size is 0!\n", 
file_name);
+        return ERROR_INVAL;
+    }
+
+    return 0;
+}
+
 int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid, libxl_device_disk 
*disk)
 {
     libxl__gc gc = LIBXL_INIT_GC(ctx);
@@ -835,6 +864,10 @@ int libxl_device_disk_add(libxl_ctx *ctx
     int devid;
     libxl__device device;
     int major, minor, rc;
+
+    rc = validate_virtual_disk(ctx, disk->physpath, disk->phystype);
+    if (rc)
+        return rc;

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



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