[Linaro-uefi] Platforms/AMD/Styx: implement h/w based EFI_RNG_PROTOCOL

Message ID 1461772202-6504-1-git-send-email-ard.biesheuvel@linaro.org
State New
Headers show

Commit Message

Ard Biesheuvel April 27, 2016, 3:50 p.m.
This implements the EFI_RNG_PROTOCOL protocol based on the True Random
Number Generator (TRNG) that can be found in Seattle SOCs. Note that only
the raw EFI RNG algorithm is exposed, since this is essentially what the
hardware supplies, and deterministic algorithms could potentially be
implemented on top of this by another driver.

The primary purpose currently is to enable the arm64 Linux KASLR
implementation to randomize the kernel VA space at early boot time.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 Platforms/AMD/Styx/Drivers/StyxRngDxe/StyxRngDxe.c   | 189 ++++++++++++++++++++
 Platforms/AMD/Styx/Drivers/StyxRngDxe/StyxRngDxe.inf |  47 +++++
 2 files changed, 236 insertions(+)

Patch

diff --git a/Platforms/AMD/Styx/Drivers/StyxRngDxe/StyxRngDxe.c b/Platforms/AMD/Styx/Drivers/StyxRngDxe/StyxRngDxe.c
new file mode 100644
index 000000000000..c3de0b9f5c33
--- /dev/null
+++ b/Platforms/AMD/Styx/Drivers/StyxRngDxe/StyxRngDxe.c
@@ -0,0 +1,189 @@ 
+/** @file
+
+  This driver produces an EFI_RNG_PROTOCOL instance for the AMD Seattle CCP
+
+  Copyright (C) 2016, Linaro Ltd.
+
+  This program and the accompanying materials are licensed and made available
+  under the terms and conditions of the BSD License which accompanies this
+  distribution. The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
+  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+#include <Library/BaseMemoryLib.h>
+#include <Library/PcdLib.h>
+#include <Library/IoLib.h>
+
+#include <Protocol/Rng.h>
+
+#define CCP_TRNG_OFFSET     0xc
+#define CCP_TNRG_RETRIES    5
+
+STATIC EFI_PHYSICAL_ADDRESS mCcpRngOutputReg;
+
+STATIC EFI_HANDLE mHandle;
+
+/**
+  Returns information about the random number generation implementation.
+
+  @param[in]     This                 A pointer to the EFI_RNG_PROTOCOL
+                                      instance.
+  @param[in,out] RNGAlgorithmListSize On input, the size in bytes of
+                                      RNGAlgorithmList.
+                                      On output with a return code of
+                                      EFI_SUCCESS, the size in bytes of the
+                                      data returned in RNGAlgorithmList. On
+                                      output with a return code of
+                                      EFI_BUFFER_TOO_SMALL, the size of
+                                      RNGAlgorithmList required to obtain the
+                                      list.
+  @param[out] RNGAlgorithmList        A caller-allocated memory buffer filled
+                                      by the driver with one EFI_RNG_ALGORITHM
+                                      element for each supported RNG algorithm.
+                                      The list must not change across multiple
+                                      calls to the same driver. The first
+                                      algorithm in the list is the default
+                                      algorithm for the driver.
+
+  @retval EFI_SUCCESS                 The RNG algorithm list was returned
+                                      successfully.
+  @retval EFI_UNSUPPORTED             The services is not supported by this
+                                      driver.
+  @retval EFI_DEVICE_ERROR            The list of algorithms could not be
+                                      retrieved due to a hardware or firmware
+                                      error.
+  @retval EFI_INVALID_PARAMETER       One or more of the parameters are
+                                      incorrect.
+  @retval EFI_BUFFER_TOO_SMALL        The buffer RNGAlgorithmList is too small
+                                      to hold the result.
+
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+StyxRngGetInfo (
+  IN      EFI_RNG_PROTOCOL        *This,
+  IN OUT  UINTN                   *RNGAlgorithmListSize,
+  OUT     EFI_RNG_ALGORITHM       *RNGAlgorithmList
+  )
+{
+  if (This == NULL || RNGAlgorithmListSize == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  if (*RNGAlgorithmListSize < sizeof (EFI_RNG_ALGORITHM)) {
+    *RNGAlgorithmListSize = sizeof (EFI_RNG_ALGORITHM);
+    return EFI_BUFFER_TOO_SMALL;
+  }
+
+  if (RNGAlgorithmList == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  *RNGAlgorithmListSize = sizeof (EFI_RNG_ALGORITHM);
+  CopyGuid (RNGAlgorithmList, &gEfiRngAlgorithmRaw);
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Produces and returns an RNG value using either the default or specified RNG
+  algorithm.
+
+  @param[in]  This                    A pointer to the EFI_RNG_PROTOCOL
+                                      instance.
+  @param[in]  RNGAlgorithm            A pointer to the EFI_RNG_ALGORITHM that
+                                      identifies the RNG algorithm to use. May
+                                      be NULL in which case the function will
+                                      use its default RNG algorithm.
+  @param[in]  RNGValueLength          The length in bytes of the memory buffer
+                                      pointed to by RNGValue. The driver shall
+                                      return exactly this numbers of bytes.
+  @param[out] RNGValue                A caller-allocated memory buffer filled
+                                      by the driver with the resulting RNG
+                                      value.
+
+  @retval EFI_SUCCESS                 The RNG value was returned successfully.
+  @retval EFI_UNSUPPORTED             The algorithm specified by RNGAlgorithm
+                                      is not supported by this driver.
+  @retval EFI_DEVICE_ERROR            An RNG value could not be retrieved due
+                                      to a hardware or firmware error.
+  @retval EFI_NOT_READY               There is not enough random data available
+                                      to satisfy the length requested by
+                                      RNGValueLength.
+  @retval EFI_INVALID_PARAMETER       RNGValue is NULL or RNGValueLength is
+                                      zero.
+
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+StyxRngGetRNG (
+  IN EFI_RNG_PROTOCOL            *This,
+  IN EFI_RNG_ALGORITHM           *RNGAlgorithm, OPTIONAL
+  IN UINTN                       RNGValueLength,
+  OUT UINT8                      *RNGValue
+  )
+{
+  UINT32 Val;
+  UINT32 Retries;
+  UINT32 Loop;
+
+  if (This == NULL || RNGValueLength == 0 || RNGValue == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  //
+  // We only support the raw algorithm, so reject requests for anything else
+  //
+  if (RNGAlgorithm != NULL &&
+      !CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmRaw)) {
+    return EFI_UNSUPPORTED;
+  }
+
+  do {
+    Retries = CCP_TNRG_RETRIES;
+    do {
+      Val = MmioRead32 (mCcpRngOutputReg);
+    } while (!Val && Retries-- > 0);
+
+    if (!Val) {
+      return EFI_DEVICE_ERROR;
+    }
+
+    for (Loop = 0; Loop < 4 && RNGValueLength > 0; Loop++, RNGValueLength--) {
+      *RNGValue++ = (UINT8)Val;
+      Val >>= 8;
+    }
+  } while (RNGValueLength > 0);
+
+  return EFI_SUCCESS;
+}
+
+STATIC EFI_RNG_PROTOCOL mStyxRngProtocol = {
+  StyxRngGetInfo,
+  StyxRngGetRNG
+};
+
+//
+// Entry point of this driver.
+//
+EFI_STATUS
+EFIAPI
+StyxRngEntryPoint (
+  IN EFI_HANDLE       ImageHandle,
+  IN EFI_SYSTEM_TABLE *SystemTable
+  )
+{
+  mCcpRngOutputReg = PcdGet64 (PcdCCPBase) + CCP_TRNG_OFFSET;
+
+  return SystemTable->BootServices->InstallMultipleProtocolInterfaces (
+                                      &mHandle,
+                                      &gEfiRngProtocolGuid, &mStyxRngProtocol,
+                                      NULL
+                                      );
+}
diff --git a/Platforms/AMD/Styx/Drivers/StyxRngDxe/StyxRngDxe.inf b/Platforms/AMD/Styx/Drivers/StyxRngDxe/StyxRngDxe.inf
new file mode 100644
index 000000000000..3ffb69d8aade
--- /dev/null
+++ b/Platforms/AMD/Styx/Drivers/StyxRngDxe/StyxRngDxe.inf
@@ -0,0 +1,47 @@ 
+## @file
+# This driver produces an EFI_RNG_PROTOCOL instance for the AMD Seattle CCP
+#
+# Copyright (C) 2016, Linaro Ltd.
+#
+# This program and the accompanying materials are licensed and made available
+# under the terms and conditions of the BSD License which accompanies this
+# distribution. The full text of the license may be found at
+# http://opensource.org/licenses/bsd-license.php
+#
+# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
+# WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = StyxRngDxe
+  FILE_GUID                      = 58E26F0D-CBAC-4BBA-B70F-18221415665A
+  MODULE_TYPE                    = DXE_DRIVER
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = StyxRngEntryPoint
+
+[Sources]
+  StyxRngDxe.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  AmdModulePkg/AmdModulePkg.dec
+
+[LibraryClasses]
+  BaseMemoryLib
+  IoLib
+  PcdLib
+  UefiDriverEntryPoint
+
+[Pcd]
+  gAmdModulePkgTokenSpaceGuid.PcdCCPBase
+
+[Protocols]
+  gEfiRngProtocolGuid              ## PRODUCES
+
+[Guids]
+  gEfiRngAlgorithmRaw
+
+[Depex]
+  TRUE