NetworkPkg: Dhcp6Dxe: SECURITY PATCH CVE-2023-45230 Patch

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=4535

PixieFail Bug #2
CVE-2023-45230
CVSS 8.3 : CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
CWE-119 Improper Restriction of Operations within the Bounds
 of a Memory Buffer

Changes Overview:
> -UINT8 *
> +EFI_STATUS
>  Dhcp6AppendOption (
> -  IN OUT UINT8   *Buf,
> -  IN     UINT16  OptType,
> -  IN     UINT16  OptLen,
> -  IN     UINT8   *Data
> +  IN OUT EFI_DHCP6_PACKET  *Packet,
> +  IN OUT UINT8             **PacketCursor,
> +  IN     UINT16            OptType,
> +  IN     UINT16            OptLen,
> +  IN     UINT8             *Data
>    );

Dhcp6AppendOption() and variants can return errors now.  All callsites
are adapted accordingly.

It gets passed in EFI_DHCP6_PACKET as additional parameter ...

> +  //
> +  // Verify the PacketCursor is within the packet
> +  //
> +  if (  (*PacketCursor < Packet->Dhcp6.Option)
> +     || (*PacketCursor >= Packet->Dhcp6.Option +
 (Packet->Size - sizeof (EFI_DHCP6_HEADER))))
> +  {
> +    return EFI_INVALID_PARAMETER;
> +  }

... so it can look at Packet->Size when checking buffer space.
Also to allow Packet->Length updates.

Lots of checks added.

Cc: Saloni Kasbekar <saloni.kasbekar@intel.com>
Cc: Zachary Clark-williams <zachary.clark-williams@intel.com>

Signed-off-by: Doug Flick [MSFT] <doug.edk2@gmail.com>
Reviewed-by: Saloni Kasbekar <saloni.kasbekar@intel.com>
Reviewed-by: Jeff Brasen <jbrasen@nvidia.com>
Tested-by: Jeff Brasen <jbrasen@nvidia.com>

NetworkPkg/Dhcp6Dxe/Dhcp6Impl.h

@@ -45,6 +45,49 @@ typedef struct _DHCP6_INSTANCE  DHCP6_INSTANCE;
 #define DHCP6_SERVICE_SIGNATURE   SIGNATURE_32 ('D', 'H', '6', 'S')
 #define DHCP6_INSTANCE_SIGNATURE  SIGNATURE_32 ('D', 'H', '6', 'I')
 
+//
+// For more information on DHCP options see RFC 8415, Section 21.1
+//
+// The format of DHCP options is:
+//
+//     0                   1                   2                   3
+//     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//    |          option-code          |           option-len          |
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//    |                          option-data                          |
+//    |                      (option-len octets)                      |
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//
+#define DHCP6_SIZE_OF_OPT_CODE  (sizeof(UINT16))
+#define DHCP6_SIZE_OF_OPT_LEN   (sizeof(UINT16))
+
+//
+// Combined size of Code and Length
+//
+#define DHCP6_SIZE_OF_COMBINED_CODE_AND_LEN  (DHCP6_SIZE_OF_OPT_CODE + \
+                                              DHCP6_SIZE_OF_OPT_LEN)
+
+STATIC_ASSERT (
+  DHCP6_SIZE_OF_COMBINED_CODE_AND_LEN == 4,
+  "Combined size of Code and Length must be 4 per RFC 8415"
+  );
+
+//
+// Offset to the length is just past the code
+//
+#define DHCP6_OPT_LEN_OFFSET(a)  (a + DHCP6_SIZE_OF_OPT_CODE)
+STATIC_ASSERT (
+  DHCP6_OPT_LEN_OFFSET (0) == 2,
+  "Offset of length is + 2 past start of option"
+  );
+
+#define DHCP6_OPT_DATA_OFFSET(a)  (a + DHCP6_SIZE_OF_COMBINED_CODE_AND_LEN)
+STATIC_ASSERT (
+  DHCP6_OPT_DATA_OFFSET (0) == 4,
+  "Offset to option data should be +4 from start of option"
+  );
+
 #define DHCP6_PACKET_ALL        0
 #define DHCP6_PACKET_STATEFUL   1
 #define DHCP6_PACKET_STATELESS  2