[PATCH v4 2/7] OvmfPkg: add 'initrd' shell command to expose Linux initrd via device path

["Ard Biesheuvel" <ard.biesheuvel@linaro.org>]

Add a new 'initrd' command to the UEFI Shell that allows any file that is
accessible to the shell to be registered as the initrd that is returned
when Linux's EFI stub loader invokes the LoadFile2 protocol on its special
vendor media device path.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2564
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
---
 OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c   | 429 ++++++++++++++++++++
 OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.inf |  53 +++
 OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni |  49 +++
 3 files changed, 531 insertions(+)

diff --git a/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c
new file mode 100644
index 000000000000..47ed26b50d3a
--- /dev/null
+++ b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c
@@ -0,0 +1,429 @@
+/** @file
+  Provides 'initrd' dynamic UEFI shell command to load a Linux initrd
+  via its GUIDed vendor media path
+
+  Copyright (c) 2020, Arm, Ltd. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Uefi.h>
+
+#include <Library/DebugLib.h>
+#include <Library/DevicePathLib.h>
+#include <Library/HiiLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/ShellLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiHiiServicesLib.h>
+
+#include <Guid/LinuxEfiInitrdMedia.h>
+
+#include <Protocol/DevicePath.h>
+#include <Protocol/HiiPackageList.h>
+#include <Protocol/LoadFile2.h>
+#include <Protocol/ShellDynamicCommand.h>
+
+#pragma pack (1)
+typedef struct {
+  VENDOR_DEVICE_PATH          VenMediaNode;
+  EFI_DEVICE_PATH_PROTOCOL    EndNode;
+} SINGLE_NODE_VENDOR_MEDIA_DEVPATH;
+#pragma pack ()
+
+STATIC EFI_HII_HANDLE         mLinuxInitrdShellCommandHiiHandle;
+STATIC EFI_PHYSICAL_ADDRESS   mInitrdFileAddress;
+STATIC UINTN                  mInitrdFileSize;
+STATIC EFI_HANDLE             mInitrdLoadFile2Handle;
+
+STATIC CONST SHELL_PARAM_ITEM ParamList[] = {
+  {L"-u", TypeFlag},
+  {NULL, TypeMax}
+  };
+
+STATIC CONST SINGLE_NODE_VENDOR_MEDIA_DEVPATH mInitrdDevicePath = {
+  {
+    {
+      MEDIA_DEVICE_PATH, MEDIA_VENDOR_DP, { sizeof (VENDOR_DEVICE_PATH) }
+    },
+    LINUX_EFI_INITRD_MEDIA_GUID
+  }, {
+    END_DEVICE_PATH_TYPE, END_ENTIRE_DEVICE_PATH_SUBTYPE,
+    { sizeof (EFI_DEVICE_PATH_PROTOCOL) }
+  }
+};
+
+STATIC
+EFI_STATUS
+EFIAPI
+InitrdLoadFile2 (
+  IN      EFI_LOAD_FILE2_PROTOCOL       *This,
+  IN      EFI_DEVICE_PATH_PROTOCOL      *FilePath,
+  IN      BOOLEAN                       BootPolicy,
+  IN  OUT UINTN                         *BufferSize,
+  OUT     VOID                          *Buffer     OPTIONAL
+  )
+{
+  if (BootPolicy) {
+    return EFI_UNSUPPORTED;
+  }
+
+  if (BufferSize == NULL || !IsDevicePathValid (FilePath, 0)) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  if (FilePath->Type != END_DEVICE_PATH_TYPE ||
+      FilePath->SubType != END_ENTIRE_DEVICE_PATH_SUBTYPE ||
+      mInitrdFileSize == 0) {
+    return EFI_NOT_FOUND;
+  }
+
+  if (Buffer == NULL || *BufferSize < mInitrdFileSize) {
+    *BufferSize = mInitrdFileSize;
+    return EFI_BUFFER_TOO_SMALL;
+  }
+
+  ASSERT (mInitrdFileAddress != 0);
+
+  gBS->CopyMem (Buffer, (VOID *)(UINTN)mInitrdFileAddress, mInitrdFileSize);
+  *BufferSize = mInitrdFileSize;
+  return EFI_SUCCESS;
+}
+
+STATIC CONST EFI_LOAD_FILE2_PROTOCOL     mInitrdLoadFile2 = {
+  InitrdLoadFile2,
+};
+
+STATIC
+EFI_STATUS
+UninstallLoadFile2Protocol (
+  VOID
+  )
+{
+  EFI_STATUS    Status;
+
+  if (mInitrdLoadFile2Handle != NULL) {
+    Status = gBS->UninstallMultipleProtocolInterfaces (mInitrdLoadFile2Handle,
+                    &gEfiDevicePathProtocolGuid,    &mInitrdDevicePath,
+                    &gEfiLoadFile2ProtocolGuid,     &mInitrdLoadFile2,
+                    NULL);
+    if (!EFI_ERROR (Status)) {
+      mInitrdLoadFile2Handle = NULL;
+    }
+  }
+  return Status;
+}
+
+STATIC
+VOID
+FreeInitrdFile (
+  VOID
+  )
+{
+  if (mInitrdFileSize != 0) {
+    gBS->FreePages (mInitrdFileAddress, EFI_SIZE_TO_PAGES (mInitrdFileSize));
+    mInitrdFileSize = 0;
+  }
+}
+
+STATIC
+EFI_STATUS
+CacheInitrdFile (
+  IN  SHELL_FILE_HANDLE   FileHandle
+  )
+{
+  EFI_STATUS              Status;
+  UINT64                  FileSize;
+  UINTN                   ReadSize;
+
+  Status = gEfiShellProtocol->GetFileSize (FileHandle, &FileSize);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  if (FileSize == 0 || FileSize > MAX_UINTN) {
+    return EFI_UNSUPPORTED;
+  }
+
+  Status = gBS->AllocatePages (AllocateAnyPages, EfiLoaderData,
+                  EFI_SIZE_TO_PAGES ((UINTN)FileSize), &mInitrdFileAddress);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  ReadSize = (UINTN)FileSize;
+  Status = gEfiShellProtocol->ReadFile (FileHandle, &ReadSize,
+                                (VOID *)(UINTN)mInitrdFileAddress);
+  if (EFI_ERROR (Status) || ReadSize < FileSize) {
+    DEBUG ((DEBUG_WARN, "%a: failed to read initrd file - %r 0x%lx 0x%lx\n",
+      __FUNCTION__, Status, (UINT64)ReadSize, FileSize));
+    goto FreeMemory;
+  }
+
+  if (mInitrdLoadFile2Handle == NULL) {
+    Status = gBS->InstallMultipleProtocolInterfaces (&mInitrdLoadFile2Handle,
+                    &gEfiDevicePathProtocolGuid,  &mInitrdDevicePath,
+                    &gEfiLoadFile2ProtocolGuid,   &mInitrdLoadFile2,
+                    NULL);
+    ASSERT_EFI_ERROR (Status);
+  }
+
+  mInitrdFileSize = FileSize;
+  return EFI_SUCCESS;
+
+FreeMemory:
+  gBS->FreePages (mInitrdFileAddress, EFI_SIZE_TO_PAGES ((UINTN)FileSize));
+  return Status;
+}
+
+/**
+  Function for 'initrd' command.
+
+  @param[in] ImageHandle  Handle to the Image (NULL if Internal).
+  @param[in] SystemTable  Pointer to the System Table (NULL if Internal).
+**/
+STATIC
+SHELL_STATUS
+EFIAPI
+RunInitrd (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  EFI_STATUS            Status;
+  LIST_ENTRY            *Package;
+  CHAR16                *ProblemParam;
+  CONST CHAR16          *Param;
+  CHAR16                *Filename;
+  SHELL_STATUS          ShellStatus;
+  SHELL_FILE_HANDLE     FileHandle;
+
+  ProblemParam        = NULL;
+  ShellStatus         = SHELL_SUCCESS;
+
+  Status = ShellInitialize ();
+  ASSERT_EFI_ERROR (Status);
+
+  //
+  // parse the command line
+  //
+  Status = ShellCommandLineParse (ParamList, &Package, &ProblemParam, TRUE);
+  if (EFI_ERROR (Status)) {
+    if (Status == EFI_VOLUME_CORRUPTED && ProblemParam != NULL) {
+      ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_PROBLEM),
+        mLinuxInitrdShellCommandHiiHandle, L"initrd", ProblemParam);
+      FreePool (ProblemParam);
+      ShellStatus = SHELL_INVALID_PARAMETER;
+    } else {
+      ASSERT(FALSE);
+    }
+  } else {
+    if (ShellCommandLineGetCount (Package) > 2) {
+      ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_TOO_MANY),
+        mLinuxInitrdShellCommandHiiHandle, L"initrd");
+      ShellStatus = SHELL_INVALID_PARAMETER;
+    } else if (ShellCommandLineGetCount (Package) < 2) {
+      if (ShellCommandLineGetFlag (Package, L"-u")) {
+        FreeInitrdFile ();
+        UninstallLoadFile2Protocol ();
+      } else {
+        ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_TOO_FEW),
+          mLinuxInitrdShellCommandHiiHandle, L"initrd");
+        ShellStatus = SHELL_INVALID_PARAMETER;
+      }
+    } else {
+      Param = ShellCommandLineGetRawValue (Package, 1);
+      ASSERT (Param != NULL);
+
+      Filename = ShellFindFilePath (Param);
+      if (Filename == NULL) {
+        ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_FIND_FAIL),
+          mLinuxInitrdShellCommandHiiHandle, L"initrd", Param);
+        ShellStatus = SHELL_NOT_FOUND;
+      } else {
+        Status = ShellOpenFileByName (Filename, &FileHandle,
+                   EFI_FILE_MODE_READ, 0);
+        if (!EFI_ERROR (Status)) {
+          FreeInitrdFile ();
+          Status = CacheInitrdFile (FileHandle);
+          ShellCloseFile (&FileHandle);
+        }
+        if (EFI_ERROR (Status)) {
+          ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_FILE_OPEN_FAIL),
+            mLinuxInitrdShellCommandHiiHandle, L"initrd", Param);
+          ShellStatus = SHELL_NOT_FOUND;
+        }
+        FreePool (Filename);
+      }
+    }
+  }
+  return ShellStatus;
+}
+
+
+/**
+  This is the shell command handler function pointer callback type.  This
+  function handles the command when it is invoked in the shell.
+
+  @param[in] This                   The instance of the
+                                    EFI_SHELL_DYNAMIC_COMMAND_PROTOCOL.
+  @param[in] SystemTable            The pointer to the system table.
+  @param[in] ShellParameters        The parameters associated with the command.
+  @param[in] Shell                  The instance of the shell protocol used in
+                                    the context of processing this command.
+
+  @return EFI_SUCCESS               the operation was successful
+  @return other                     the operation failed.
+**/
+SHELL_STATUS
+EFIAPI
+LinuxInitrdCommandHandler (
+  IN EFI_SHELL_DYNAMIC_COMMAND_PROTOCOL    *This,
+  IN EFI_SYSTEM_TABLE                      *SystemTable,
+  IN EFI_SHELL_PARAMETERS_PROTOCOL         *ShellParameters,
+  IN EFI_SHELL_PROTOCOL                    *Shell
+  )
+{
+  gEfiShellParametersProtocol = ShellParameters;
+  gEfiShellProtocol           = Shell;
+
+  return RunInitrd (gImageHandle, SystemTable);
+}
+
+/**
+  This is the command help handler function pointer callback type.  This
+  function is responsible for displaying help information for the associated
+  command.
+
+  @param[in] This                   The instance of the
+                                    EFI_SHELL_DYNAMIC_COMMAND_PROTOCOL.
+  @param[in] Language               The pointer to the language string to use.
+
+  @return string                    Pool allocated help string, must be freed
+                                    by caller
+**/
+STATIC
+CHAR16 *
+EFIAPI
+LinuxInitrdGetHelp (
+  IN EFI_SHELL_DYNAMIC_COMMAND_PROTOCOL    *This,
+  IN CONST CHAR8                           *Language
+  )
+{
+  return HiiGetString (mLinuxInitrdShellCommandHiiHandle,
+           STRING_TOKEN (STR_GET_HELP_INITRD), Language);
+}
+
+STATIC EFI_SHELL_DYNAMIC_COMMAND_PROTOCOL mLinuxInitrdDynamicCommand = {
+  L"initrd",
+  LinuxInitrdCommandHandler,
+  LinuxInitrdGetHelp
+};
+
+/**
+  Retrieve HII package list from ImageHandle and publish to HII database.
+
+  @param ImageHandle            The image handle of the process.
+
+  @return HII handle.
+**/
+STATIC
+EFI_HII_HANDLE
+InitializeHiiPackage (
+  EFI_HANDLE                  ImageHandle
+  )
+{
+  EFI_STATUS                  Status;
+  EFI_HII_PACKAGE_LIST_HEADER *PackageList;
+  EFI_HII_HANDLE              HiiHandle;
+
+  //
+  // Retrieve HII package list from ImageHandle
+  //
+  Status = gBS->OpenProtocol (ImageHandle, &gEfiHiiPackageListProtocolGuid,
+                  (VOID **)&PackageList, ImageHandle, NULL,
+                  EFI_OPEN_PROTOCOL_GET_PROTOCOL);
+  ASSERT_EFI_ERROR (Status);
+  if (EFI_ERROR (Status)) {
+    return NULL;
+  }
+
+  //
+  // Publish HII package list to HII Database.
+  //
+  Status = gHiiDatabase->NewPackageList (gHiiDatabase, PackageList, NULL,
+                           &HiiHandle);
+  ASSERT_EFI_ERROR (Status);
+  if (EFI_ERROR (Status)) {
+    return NULL;
+  }
+  return HiiHandle;
+}
+
+/**
+  Entry point of Linux Initrd dynamic UEFI Shell command.
+
+  Produce the DynamicCommand protocol to handle "initrd" command.
+
+  @param ImageHandle            The image handle of the process.
+  @param SystemTable            The EFI System Table pointer.
+
+  @retval EFI_SUCCESS           Initrd command is executed successfully.
+  @retval EFI_ABORTED           HII package was failed to initialize.
+  @retval others                Other errors when executing Initrd command.
+**/
+EFI_STATUS
+EFIAPI
+LinuxInitrdDynamicShellCommandEntryPoint (
+  IN EFI_HANDLE               ImageHandle,
+  IN EFI_SYSTEM_TABLE         *SystemTable
+  )
+{
+  EFI_STATUS                  Status;
+
+  mLinuxInitrdShellCommandHiiHandle = InitializeHiiPackage (ImageHandle);
+  if (mLinuxInitrdShellCommandHiiHandle == NULL) {
+    return EFI_ABORTED;
+  }
+
+  Status = gBS->InstallProtocolInterface (&ImageHandle,
+                  &gEfiShellDynamicCommandProtocolGuid,
+                  EFI_NATIVE_INTERFACE,
+                  &mLinuxInitrdDynamicCommand);
+  ASSERT_EFI_ERROR (Status);
+  return Status;
+}
+
+/**
+  Unload the dynamic UEFI Shell command.
+
+  @param ImageHandle            The image handle of the process.
+
+  @retval EFI_SUCCESS           The image is unloaded.
+  @retval Others                Failed to unload the image.
+**/
+EFI_STATUS
+EFIAPI
+LinuxInitrdDynamicShellCommandUnload (
+  IN EFI_HANDLE               ImageHandle
+)
+{
+  EFI_STATUS                  Status;
+
+  FreeInitrdFile ();
+
+  Status = UninstallLoadFile2Protocol ();
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  Status = gBS->UninstallProtocolInterface (ImageHandle,
+                  &gEfiShellDynamicCommandProtocolGuid,
+                  &mLinuxInitrdDynamicCommand);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  HiiRemovePackages (mLinuxInitrdShellCommandHiiHandle);
+  return EFI_SUCCESS;
+}
diff --git a/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.inf b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.inf
new file mode 100644
index 000000000000..6da6ef6d7818
--- /dev/null
+++ b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.inf
@@ -0,0 +1,53 @@
+##  @file
+# Provides 'initrd' dynamic UEFI shell command to load a Linux initrd
+# via its GUIDed vendor media path
+#
+# Copyright (c) 2020, Arm, Ltd. All rights reserved.<BR>
+#
+#  SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+#
+##
+
+[Defines]
+  INF_VERSION                    = 1.27
+  BASE_NAME                      = LinuxInitrdDynamicShellCommand
+  FILE_GUID                      = 2f30da26-f51b-4b6f-85c4-31873c281bca
+  MODULE_TYPE                    = DXE_DRIVER
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = LinuxInitrdDynamicShellCommandEntryPoint
+  UNLOAD_IMAGE                   = LinuxInitrdDynamicShellCommandUnload
+  UEFI_HII_RESOURCE_SECTION      = TRUE
+
+#
+#  VALID_ARCHITECTURES           = IA32 X64 ARM AARCH64 EBC
+#
+
+[Sources.common]
+  LinuxInitrdDynamicShellCommand.c
+  LinuxInitrdDynamicShellCommand.uni
+
+[Packages]
+  MdePkg/MdePkg.dec
+  ShellPkg/ShellPkg.dec
+  MdeModulePkg/MdeModulePkg.dec
+  OvmfPkg/OvmfPkg.dec
+
+[LibraryClasses]
+  DebugLib
+  DevicePathLib
+  HiiLib
+  MemoryAllocationLib
+  ShellLib
+  UefiBootServicesTableLib
+  UefiDriverEntryPoint
+  UefiHiiServicesLib
+
+[Protocols]
+  gEfiDevicePathProtocolGuid                      ## SOMETIMES_PRODUCES
+  gEfiHiiPackageListProtocolGuid                  ## CONSUMES
+  gEfiLoadFile2ProtocolGuid                       ## SOMETIMES_PRODUCES
+  gEfiShellDynamicCommandProtocolGuid             ## PRODUCES
+
+[DEPEX]
+  TRUE
diff --git a/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni
new file mode 100644
index 000000000000..a88fa6e3641b
--- /dev/null
+++ b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni
@@ -0,0 +1,49 @@
+// /**
+//
+// Copyright (c) 2020, Arm, Ltd. All rights reserved.<BR>
+// SPDX-License-Identifier: BSD-2-Clause-Patent
+//
+// Module Name:
+//
+// LinuxInitrdDynamicShellCommand.uni
+//
+// Abstract:
+//
+// String definitions for 'initrd' UEFI Shell command
+//
+// **/
+
+/=#
+
+#langdef   en-US "english"
+
+#string STR_GEN_PROBLEM           #language en-US "%H%s%N: Unknown flag - '%H%s%N'\r\n"
+#string STR_GEN_TOO_MANY          #language en-US "%H%s%N: Too many arguments.\r\n"
+#string STR_GEN_TOO_FEW           #language en-US "%H%s%N: Too few arguments.\r\n"
+#string STR_GEN_FIND_FAIL         #language en-US "%H%s%N: File not found - '%H%s%N'\r\n"
+#string STR_GEN_FILE_OPEN_FAIL    #language en-US "%H%s%N: Cannot open file - '%H%s%N'\r\n"
+
+#string STR_GET_HELP_INITRD       #language en-US ""
+".TH initrd 0 "Registers or unregisters a file as Linux initrd."\r\n"
+".SH NAME\r\n"
+"Registers or unregisters a file as Linux initrd.\r\n"
+".SH SYNOPSIS\r\n"
+" \r\n"
+"initrd <FileName>\r\n"
+"initrd -u\r\n"
+".SH OPTIONS\r\n"
+" \r\n"
+"  FileName    - Specifies a file to register as initrd.\r\n"
+"  -u          - Unregisters any previously registered initrd files.\r\n"
+".SH DESCRIPTION\r\n"
+" \r\n"
+"NOTES:\r\n"
+"  1. Only a single file can be loaded as initrd at any given time. Using the\r\n"
+"     command twice with a <FileName> option will result in the first file to\r\n"
+"     be unloaded again, regardless of whether the second invocation succeeded\r\n"
+"     or not.\r\n"
+"  2. The initrd is not unloaded when the shell exits, and will remain active\r\n"
+"     until it is unloaded again by a different invocation of the shell.\r\n"
+"     Consumers of the LoadFile2 protocol on the LINUX_EFI_INITRD_MEDIA_GUID\r\n"
+"     device path that are started via means other than the shell will be able\r\n"
+"     to locate the protocol and invoke it.\r\n"
-- 
2.17.1