drivers/filters/fltmgr/Registry.c

   1 /*
   2  * PROJECT:         Filesystem Filter Manager
   3  * LICENSE:         GPL - See COPYING in the top level directory
   4  * FILE:            drivers/filters/fltmgr/Misc.c
   5  * PURPOSE:         Uncataloged functions
   6  * PROGRAMMERS:     Ged Murphy (gedmurphy@reactos.org)
   7  */
   8
   9 /* INCLUDES ******************************************************************/
  10
  11 #include "fltmgr.h"
  12 #include "fltmgrint.h"
  13
  14 #define NDEBUG
  15 #include <debug.h>
  16
  17
  18 /* DATA *********************************************************************/
  19
  20 #define REG_SERVICES_KEY    L"\\Registry\\Machine\\System\\CurrentControlSet\\Services\\"
  21 #define REG_PATH_LENGTH     512
  22
  23
  24 /* INTERNAL FUNCTIONS ******************************************************/
  25
  26
  27 NTSTATUS
  28 FltpOpenFilterServicesKey(
  29     _In_ PFLT_FILTER Filter,
  30     _In_ ACCESS_MASK DesiredAccess,
  31     _In_opt_ PUNICODE_STRING SubKey,
  32     _Out_ PHANDLE Handle)
  33 {
  34     OBJECT_ATTRIBUTES ObjectAttributes;
  35     UNICODE_STRING ServicesKey;
  36     UNICODE_STRING Path;
  37     WCHAR Buffer[REG_PATH_LENGTH];
  38
  39     /* Setup a local buffer to hold the services key path */
  40     Path.Length = 0;
  41     Path.MaximumLength = REG_PATH_LENGTH;
  42     Path.Buffer = Buffer;
  43
  44     /* Build up the serices key name */
  45     RtlInitUnicodeString(&ServicesKey, REG_SERVICES_KEY);
  46     RtlCopyUnicodeString(&Path, &ServicesKey);
  47     RtlAppendUnicodeStringToString(&Path, &Filter->Name);
  48
  49     if (SubKey)
  50     {
  51         /* Tag on any child key */
  52         RtlAppendUnicodeToString(&Path, L"\\");
  53         RtlAppendUnicodeStringToString(&Path, SubKey);
  54     }
  55
  56     InitializeObjectAttributes(&ObjectAttributes,
  57                                &Path,
  58                                OBJ_KERNEL_HANDLE | OBJ_CASE_INSENSITIVE,
  59                                NULL,
  60                                NULL);
  61
  62     /* Open and return the key handle param*/
  63     return ZwOpenKey(Handle, DesiredAccess, &ObjectAttributes);
  64 }
  65
  66 NTSTATUS
  67 FltpReadRegistryValue(_In_ HANDLE KeyHandle,
  68                       _In_ PUNICODE_STRING ValueName,
  69                       _In_opt_ ULONG Type,
  70                       _Out_writes_bytes_(BufferSize) PVOID Buffer,
  71                       _In_ ULONG BufferSize,
  72                       _Out_opt_ PULONG BytesRequired)
  73 {
  74     PKEY_VALUE_PARTIAL_INFORMATION Value = NULL;
  75     ULONG ValueLength = 0;
  76     NTSTATUS Status;
  77
  78     PAGED_CODE();
  79
  80     /* Get the size of the buffer required to hold the string */
  81     Status = ZwQueryValueKey(KeyHandle,
  82                              ValueName,
  83                              KeyValuePartialInformation,
  84                              NULL,
  85                              0,
  86                              &ValueLength);
  87     if (Status != STATUS_BUFFER_TOO_SMALL && Status != STATUS_BUFFER_OVERFLOW)
  88     {
  89         return Status;
  90     }
  91
  92     /* Allocate the buffer */
  93     Value = (PKEY_VALUE_PARTIAL_INFORMATION)ExAllocatePoolWithTag(PagedPool,
  94                                                                   ValueLength,
  95                                                                   FM_TAG_TEMP_REGISTRY);
  96     if (Value == NULL)
  97     {
  98         Status = STATUS_INSUFFICIENT_RESOURCES;
  99         goto Quit;
 100     }
 101
 102     /* Now read in the value */
 103     Status = ZwQueryValueKey(KeyHandle,
 104                              ValueName,
 105                              KeyValuePartialInformation,
 106                              Value,
 107                              ValueLength,
 108                              &ValueLength);
 109     if (!NT_SUCCESS(Status))
 110     {
 111         goto Quit;
 112     }
 113
 114     /* Make sure we got the type expected */
 115     if (Value->Type != Type)
 116     {
 117         Status = STATUS_INVALID_PARAMETER;
 118         goto Quit;
 119     }
 120
 121     if (BytesRequired)
 122     {
 123         *BytesRequired = Value->DataLength;
 124     }
 125
 126     /* Make sure the caller buffer is big enough to hold the data */
 127     if (!BufferSize || BufferSize < Value->DataLength)
 128     {
 129         Status = STATUS_BUFFER_TOO_SMALL;
 130         goto Quit;
 131     }
 132
 133     /* Copy the data into the caller buffer */
 134     RtlCopyMemory(Buffer, Value->Data, Value->DataLength);
 135
 136 Quit:
 137
 138     if (Value)
 139         ExFreePoolWithTag(Value, FM_TAG_TEMP_REGISTRY);
 140
 141     return Status;
 142 }