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edk2/SOURCES/0030-OvmfPkg-Add-a-Fallback...

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From 24da4bc42a6f16094ea589ffb2a9326cf8a596cc Mon Sep 17 00:00:00 2001
From: Oliver Steffen <osteffen@redhat.com>
Date: Mon, 4 Nov 2024 12:40:12 +0100
Subject: [PATCH] OvmfPkg: Add a Fallback RNG (RH only)
RH-Author: Oliver Steffen <osteffen@redhat.com>
RH-MergeRequest: 82: Add a Fallback RNG (RH only)
RH-Jira: RHEL-66234
RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>
RH-Commit: [1/2] bb62ac9e3f1cd5eae1bb94e047fb6ebada57cd24 (osteffen/edk2)
Since the pixiefail CVE fix, the network stack requires a random number
generator.
In case there is no hardware random number generator available,
have the Platform Boot Manager install a pseudo RNG to ensure
the network can be used.
Signed-off-by: Oliver Steffen <osteffen@redhat.com>
patch_name: edk2-OvmfPkg-Add-a-Fallback-RNG-RH-only.patch
present_in_specfile: true
location_in_specfile: 48
---
.../PlatformBootManagerLib/BdsPlatform.c | 7 +
.../PlatformBootManagerLib/FallbackRng.c | 222 ++++++++++++++++++
.../PlatformBootManagerLib/FallbackRng.h | 20 ++
.../PlatformBootManagerLib.inf | 5 +
4 files changed, 254 insertions(+)
create mode 100644 OvmfPkg/Library/PlatformBootManagerLib/FallbackRng.c
create mode 100644 OvmfPkg/Library/PlatformBootManagerLib/FallbackRng.h
diff --git a/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c b/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c
index d9f61757cf..87d1ac3142 100644
--- a/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c
+++ b/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c
@@ -15,6 +15,8 @@
#include <Library/Tcg2PhysicalPresenceLib.h>
#include <Library/XenPlatformLib.h>
+#include "FallbackRng.h"
+
//
// Global data
//
@@ -539,6 +541,9 @@ PlatformBootManagerBeforeConsole (
ConnectVirtioPciRng,
NULL
);
+
+ FallbackRngCheckAndInstall ();
+
}
EFI_STATUS
@@ -1778,6 +1783,8 @@ PlatformBootManagerAfterConsole (
DEBUG ((DEBUG_INFO, "PlatformBootManagerAfterConsole\n"));
+ FallbackRngPrintWarning ();
+
if (PcdGetBool (PcdOvmfFlashVariablesEnable)) {
DEBUG ((
DEBUG_INFO,
diff --git a/OvmfPkg/Library/PlatformBootManagerLib/FallbackRng.c b/OvmfPkg/Library/PlatformBootManagerLib/FallbackRng.c
new file mode 100644
index 0000000000..bba60e29d5
--- /dev/null
+++ b/OvmfPkg/Library/PlatformBootManagerLib/FallbackRng.c
@@ -0,0 +1,222 @@
+/** @file
+ Copyright (C) 2024, Red Hat, Inc.
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Uefi/UefiBaseType.h>
+#include <Uefi/UefiSpec.h>
+#include <Protocol/Rng.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/RngLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+#include <Library/PrintLib.h>
+#include <Library/DxeServicesTableLib.h>
+
+#include "FallbackRng.h"
+
+typedef struct {
+ EFI_RNG_PROTOCOL Rng;
+ EFI_HANDLE Handle;
+} FALLBACK_RNG_DEV;
+
+/**
+ 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
+FallbackRngGetInfo (
+ 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
+FallbackRngGetRNG (
+ IN EFI_RNG_PROTOCOL *This,
+ IN EFI_RNG_ALGORITHM *RNGAlgorithm OPTIONAL,
+ IN UINTN RNGValueLength,
+ OUT UINT8 *RNGValue
+ )
+{
+ UINT64 RandomData;
+ EFI_STATUS Status;
+ UINTN i;
+
+ 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;
+ }
+
+ for (i = 0; i < RNGValueLength; ++i) {
+ if (i % 4 == 0) {
+ Status = GetRandomNumber64 (&RandomData);
+ if (EFI_ERROR (Status)) {
+ return Status;
+ }
+ }
+ }
+
+ return EFI_SUCCESS;
+}
+
+static FALLBACK_RNG_DEV Dev = {
+ .Rng.GetInfo = FallbackRngGetInfo,
+ .Rng.GetRNG = FallbackRngGetRNG,
+ .Handle = NULL,
+};
+
+EFI_STATUS
+FallbackRngCheckAndInstall (
+ )
+{
+ EFI_STATUS Status;
+ EFI_HANDLE *HandleBuffer = NULL;
+ UINTN HandleCount = 0;
+
+ if (Dev.Handle != NULL) {
+ DEBUG ((DEBUG_INFO, "Fallback RNG already installed.\n"));
+ return EFI_ALREADY_STARTED;
+ }
+
+ Status = gBS->LocateHandleBuffer (
+ ByProtocol,
+ &gEfiRngProtocolGuid,
+ NULL,
+ &HandleCount,
+ &HandleBuffer
+ );
+
+ gBS->FreePool (HandleBuffer);
+
+ if (Status == EFI_NOT_FOUND) {
+ HandleCount = 0;
+ } else if (EFI_ERROR (Status)) {
+ DEBUG ((DEBUG_ERROR, "Error locating RNG protocol instances: %r\n", Status));
+ return Status;
+ }
+
+ DEBUG ((DEBUG_INFO, "Found %u RNGs\n", HandleCount));
+
+ if (HandleCount == 0) {
+ // Install RNG
+ Status = gBS->InstallProtocolInterface (
+ &Dev.Handle,
+ &gEfiRngProtocolGuid,
+ EFI_NATIVE_INTERFACE,
+ &Dev.Rng
+ );
+ if (EFI_ERROR (Status)) {
+ DEBUG ((DEBUG_ERROR, "Failed to install fallback RNG: %r\n", Status));
+ return Status;
+ }
+
+ gDS->Dispatch ();
+ }
+
+ return EFI_SUCCESS;
+}
+
+VOID
+FallbackRngPrintWarning (
+ )
+{
+ if (Dev.Handle != NULL) {
+ Print (L"WARNING: Pseudo Random Number Generator in use - Pixiefail CVE not mitigated!\n");
+ DEBUG ((DEBUG_WARN, "WARNING: Pseudo Random Number Generator in use - Pixiefail CVE not mitigated!\n"));
+ gBS->Stall (2000000);
+ }
+}
diff --git a/OvmfPkg/Library/PlatformBootManagerLib/FallbackRng.h b/OvmfPkg/Library/PlatformBootManagerLib/FallbackRng.h
new file mode 100644
index 0000000000..77332bc51c
--- /dev/null
+++ b/OvmfPkg/Library/PlatformBootManagerLib/FallbackRng.h
@@ -0,0 +1,20 @@
+/** @file
+ Copyright (C) 2024, Red Hat, Inc.
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#ifndef _FALLBACK_RNG_H_
+#define _FALLBACK_RNG_H_
+
+#include <Uefi/UefiBaseType.h>
+#include <Uefi/UefiSpec.h>
+
+EFI_STATUS
+FallbackRngCheckAndInstall (
+ );
+
+VOID
+FallbackRngPrintWarning (
+ );
+
+#endif
diff --git a/OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf b/OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf
index c6ffc1ed9e..211716e30d 100644
--- a/OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf
+++ b/OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf
@@ -25,6 +25,8 @@
PlatformData.c
QemuKernel.c
BdsPlatform.h
+ FallbackRng.c
+ FallbackRng.h
[Packages]
MdePkg/MdePkg.dec
@@ -56,6 +58,7 @@
PlatformBmPrintScLib
Tcg2PhysicalPresenceLib
XenPlatformLib
+ RngLib
[Pcd]
gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent
@@ -80,6 +83,7 @@
gEfiDxeSmmReadyToLockProtocolGuid # PROTOCOL SOMETIMES_PRODUCED
gEfiLoadedImageProtocolGuid # PROTOCOL SOMETIMES_PRODUCED
gEfiFirmwareVolume2ProtocolGuid # PROTOCOL SOMETIMES_CONSUMED
+ gEfiRngProtocolGuid # PROTOCOL SOMETIMES_PRODUCED
[Guids]
gEfiEndOfDxeEventGroupGuid
@@ -87,3 +91,4 @@
gRootBridgesConnectedEventGroupGuid
gUefiShellFileGuid
gGrubFileGuid
+ gEfiRngAlgorithmRaw
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