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dll: FspAccessCheckEx: if the desired access includes DELETE or FILE_READ_ATTRIBUTES and access was denied, check with the parent

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This commit is contained in:
Bill Zissimopoulos
2016-05-24 15:37:16 -07:00
parent aa75d412ac
commit 214b43398f
4 changed files with 93 additions and 28 deletions
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30
src/dll/fsop.c
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@ -25,6 +25,15 @@ NTSTATUS FspFileSystemCreateCheck(FSP_FILE_SYSTEM *FileSystem,
{
NTSTATUS Result;
/*
* CreateCheck consists of checking the parent directory for the
* FILE_ADD_SUBDIRECTORY or FILE_ADD_FILE rights (depending on whether
* we are creating a file or directory).
*
* If the access check succeeds and MAXIMUM_ALLOWED has been requested
* then we go ahead and grant all access to the creator.
*/
Result = FspAccessCheckEx(FileSystem, Request, TRUE, AllowTraverseCheck,
(Request->Req.Create.CreateOptions & FILE_DIRECTORY_FILE) ?
FILE_ADD_SUBDIRECTORY : FILE_ADD_FILE,
@ -45,6 +54,16 @@ NTSTATUS FspFileSystemOpenCheck(FSP_FILE_SYSTEM *FileSystem,
{
NTSTATUS Result;
/*
* OpenCheck consists of checking the file for the desired access,
* unless FILE_DELETE_ON_CLOSE is requested in which case we also
* check for DELETE access.
*
* If the access check succeeds and MAXIMUM_ALLOWED was not requested
* then we reset the DELETE access based on whether it was actually
* requested in DesiredAccess.
*/
Result = FspAccessCheck(FileSystem, Request, FALSE, AllowTraverseCheck,
Request->Req.Create.DesiredAccess |
((Request->Req.Create.CreateOptions & FILE_DELETE_ON_CLOSE) ? DELETE : 0),
@ -66,6 +85,17 @@ NTSTATUS FspFileSystemOverwriteCheck(FSP_FILE_SYSTEM *FileSystem,
NTSTATUS Result;
BOOLEAN Supersede = FILE_SUPERSEDE == ((Request->Req.Create.CreateOptions >> 24) & 0xff);
/*
* OverwriteCheck consists of checking the file for the desired access,
* unless FILE_DELETE_ON_CLOSE is requested in which case we also
* check for DELETE access. Furthermore we grant DELETE or FILE_WRITE_DATA
* access based on whether this is a Supersede or Overwrite operation.
*
* If the access check succeeds and MAXIMUM_ALLOWED was not requested
* then we reset the DELETE and FILE_WRITE_DATA accesses based on whether
* they were actually requested in DesiredAccess.
*/
Result = FspAccessCheck(FileSystem, Request, FALSE, AllowTraverseCheck,
Request->Req.Create.DesiredAccess |
(Supersede ? DELETE : FILE_WRITE_DATA) |

60
src/dll/security.c
View File

@ -61,6 +61,10 @@ FSP_API NTSTATUS FspAccessCheckEx(FSP_FILE_SYSTEM *FileSystem,
if (FspFsctlTransactCreateKind != Request->Kind)
return STATUS_INVALID_PARAMETER;
if (CheckParentDirectory &&
L'\\' == ((PWSTR)Request->Buffer)[0] && L'\0' == ((PWSTR)Request->Buffer)[1])
return STATUS_INVALID_PARAMETER;
if (0 == FileSystem->Interface->GetSecurityByName ||
(!Request->Req.Create.UserMode && 0 == PSecurityDescriptor))
{
@ -78,7 +82,7 @@ FSP_API NTSTATUS FspAccessCheckEx(FSP_FILE_SYSTEM *FileSystem,
UINT8 PrivilegeSetBuf[sizeof(PRIVILEGE_SET) + 15 * sizeof(LUID_AND_ATTRIBUTES)];
PPRIVILEGE_SET PrivilegeSet = (PVOID)PrivilegeSetBuf;
DWORD PrivilegeSetLength = sizeof PrivilegeSetBuf;
UINT32 TraverseAccess;
UINT32 TraverseAccess, ParentAccess, DesiredAccess2;
BOOL AccessStatus;
if (CheckParentDirectory)
@ -147,7 +151,54 @@ FSP_API NTSTATUS FspAccessCheckEx(FSP_FILE_SYSTEM *FileSystem,
else
Result = FspNtStatusFromWin32(GetLastError());
if (!NT_SUCCESS(Result))
goto exit;
{
/*
* If the desired access includes the DELETE or FILE_READ_ATTRIBUTES
* (or MAXIMUM_ALLOWED) rights we must still check with our parent to
* see if it gives us access (through the FILE_DELETE_CHILD and
* FILE_LIST_DIRECTORY rights).
*
* Does the Windows security model suck? Ermmmm...
*/
if (STATUS_ACCESS_DENIED != Result ||
0 == ((MAXIMUM_ALLOWED | DELETE | FILE_READ_ATTRIBUTES) & DesiredAccess))
goto exit;
Result = FspAccessCheck(FileSystem, Request, TRUE, FALSE,
(MAXIMUM_ALLOWED & DesiredAccess) ? (FILE_DELETE_CHILD | FILE_LIST_DIRECTORY) :
(
((DELETE & DesiredAccess) ? FILE_DELETE_CHILD : 0) |
((FILE_READ_ATTRIBUTES & DesiredAccess) ? FILE_LIST_DIRECTORY : 0)
),
&ParentAccess);
if (!NT_SUCCESS(Result))
{
/* any failure just becomes ACCESS DENIED at this point */
Result = STATUS_ACCESS_DENIED;
goto exit;
}
/* redo the access check but remove the DELETE and/or FILE_READ_ATTRIBUTES rights */
DesiredAccess2 = DesiredAccess & ~(
((FILE_DELETE_CHILD & ParentAccess) ? DELETE : 0) |
((FILE_LIST_DIRECTORY & ParentAccess) ? FILE_READ_ATTRIBUTES : 0));
if (0 != DesiredAccess2)
{
if (AccessCheck(SecurityDescriptor, (HANDLE)Request->Req.Create.AccessToken, DesiredAccess2,
&FspFileGenericMapping, PrivilegeSet, &PrivilegeSetLength, PGrantedAccess, &AccessStatus))
Result = AccessStatus ? STATUS_SUCCESS : STATUS_ACCESS_DENIED;
else
/* any failure just becomes ACCESS DENIED at this point */
Result = STATUS_ACCESS_DENIED;
if (!NT_SUCCESS(Result))
goto exit;
}
if (FILE_DELETE_CHILD & ParentAccess)
*PGrantedAccess |= DELETE;
if (FILE_LIST_DIRECTORY & ParentAccess)
*PGrantedAccess |= FILE_READ_ATTRIBUTES;
}
}
if (CheckParentDirectory)
@ -192,6 +243,11 @@ FSP_API NTSTATUS FspAccessCheckEx(FSP_FILE_SYSTEM *FileSystem,
if (0 == SecurityDescriptorSize)
*PGrantedAccess = (MAXIMUM_ALLOWED & DesiredAccess) ?
FspFileGenericMapping.GenericAll : DesiredAccess;
if (0 != (FileAttributes & FILE_ATTRIBUTE_READONLY) &&
0 != (MAXIMUM_ALLOWED & DesiredAccess))
*PGrantedAccess &= ~(FILE_WRITE_DATA | FILE_APPEND_DATA |
FILE_ADD_SUBDIRECTORY | FILE_DELETE_CHILD);
}
else
*PGrantedAccess = (MAXIMUM_ALLOWED & DesiredAccess) ?