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Windows: Don't restore MBR to VeraCrypt value if it is coming from a loader different from us or different from Microsoft one.

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This commit is contained in:
Mounir IDRASSI
2019-11-26 09:55:56 +01:00
parent 9741c9209d
commit 79eea6e5b1
1 changed files with 25 additions and 2 deletions
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27
src/Common/BootEncryption.cpp
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@@ -275,6 +275,27 @@ bool ZipAdd (zip_t *z, const char* name, const unsigned char* pbData, DWORD cbDa
return true; return true;
} }
static BOOL IsWindowsMBR (const byte *buffer, size_t bufferSize)
{
BOOL bRet = FALSE;
byte g_pbMsSignature[4] = {0x33, 0xc0, 0x8e, 0xd0};
const char* g_szStr1 = "Invalid partition table";
const char* g_szStr2 = "Error loading operating system";
const char* g_szStr3 = "Missing operating system";
if ((0 == memcmp (buffer, g_pbMsSignature, 4)) &&
(BufferContainsString (buffer, bufferSize, g_szStr1)
|| BufferContainsString (buffer, bufferSize, g_szStr2)
|| BufferContainsString (buffer, bufferSize, g_szStr3)
)
)
{
bRet = TRUE;
}
return bRet;
}
namespace VeraCrypt namespace VeraCrypt
{ {
#if !defined (SETUP) #if !defined (SETUP)
@@ -3546,8 +3567,10 @@ namespace VeraCrypt
} }
} }
// perform actual write only if content is different // perform actual write only if content is different and either we are not in PostOOBE mode or the MBR contains VeraCrypt/Windows signature.
if (memcmp (mbr, bootLoaderBuf, TC_MAX_MBR_BOOT_CODE_SIZE)) // this last check is done to avoid interfering with multi-boot configuration where MBR belongs to a boot manager like Grub
if (memcmp (mbr, bootLoaderBuf, TC_MAX_MBR_BOOT_CODE_SIZE)
&& (!PostOOBEMode || BufferContainsString (mbr, sizeof (mbr), TC_APP_NAME) || IsWindowsMBR (mbr, sizeof (mbr))))
{ {
memcpy (mbr, bootLoaderBuf, TC_MAX_MBR_BOOT_CODE_SIZE); memcpy (mbr, bootLoaderBuf, TC_MAX_MBR_BOOT_CODE_SIZE);