[Xen-changelog] [xen-unstable] vtpm: Fix hashed-memory file writing.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1251097426 -3600
# Node ID 3a6aaadaa035fcce2ea8b6cef2e282d9cec672d1
# Parent  7e194320394244bc5028881b498d2e01574086cd
vtpm: Fix hashed-memory file writing.

There is a bug in the vtpm_manager that has to do with hashing and
saving the NVM memory files (vtpm_dm_%d.data). The file is not
truncated when it is written and this results in the hash becoming
invalid because of the extra bits at the end of the file.

This patch adds O_TRUNC to the flags when opening the file.

More details on this issue are in the bug report on bugzilla=20
http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=3D1488

Signed-off-by: Matt Fioravante <Matthew.Fioravante@xxxxxxxxxx>
---
 tools/vtpm_manager/manager/securestorage.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

diff -r 7e1943203942 -r 3a6aaadaa035 tools/vtpm_manager/manager/securestorage.c
--- a/tools/vtpm_manager/manager/securestorage.c        Mon Aug 24 08:02:08 
2009 +0100
+++ b/tools/vtpm_manager/manager/securestorage.c        Mon Aug 24 08:03:46 
2009 +0100
@@ -199,7 +199,7 @@ TPM_RESULT VTPM_Handle_Save_NVM(VTPM_DMI
   // TODO: How to properly return from these. Do we care if we return failure
   //       after writing the file? We can't get the old one back.
   // TODO: Backup old file and try and recover that way.
-  fh = open(myDMI->NVMLocation, O_WRONLY | O_CREAT, S_IREAD | S_IWRITE);
+  fh = open(myDMI->NVMLocation, O_WRONLY | O_CREAT | O_TRUNC, S_IREAD | 
S_IWRITE);
   if ( (bytes_written = write(fh, sealed_NVM.bytes, buffer_len(&sealed_NVM) ) 
!= (long) buffer_len(&sealed_NVM))) {
     vtpmlogerror(VTPM_LOG_VTPM, "We just overwrote a DMI_NVM and failed to 
finish. %ld/%ld bytes.\n", bytes_written, (long)buffer_len(&sealed_NVM));
     status = TPM_IOERROR;

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