src/boot/efi/shim.c - systemd-stable - Rivoreo Source Code Repositories

 /*
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU Lesser General Public License as published by
  * the Free Software Foundation; either version 2.1 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  * Lesser General Public License for more details.
  *
  * Port to systemd-boot
  * Copyright 2017 Max Resch <resch.max@gmail.com>
  *
  * Security Policy Handling
  * Copyright 2012 <James.Bottomley@HansenPartnership.com>
  * https://github.com/mjg59/efitools
  */

 #include <efi.h>
 #include <efilib.h>

 #include "util.h"
 #include "shim.h"

 /* well known shim lock guid */
 #define SHIM_LOCK_GUID

 struct ShimLock {
         EFI_STATUS __attribute__((sysv_abi)) (*shim_verify) (VOID *buffer, UINT32 size);

         /* context is actually a struct for the PE header, but it isn't needed so void is sufficient just do define the interface
          * see shim.c/shim.h and PeHeader.h in the github shim repo */
         EFI_STATUS __attribute__((sysv_abi)) (*generate_hash) (VOID *data, UINT32 datasize, VOID *context, UINT8 *sha256hash, UINT8 *sha1hash);

         EFI_STATUS __attribute__((sysv_abi)) (*read_header) (VOID *data, UINT32 datasize, VOID *context);
 };

 static const EFI_GUID simple_fs_guid = SIMPLE_FILE_SYSTEM_PROTOCOL;
 static const EFI_GUID global_guid = EFI_GLOBAL_VARIABLE;

 static const EFI_GUID security_protocol_guid = { 0xa46423e3, 0x4617, 0x49f1, {0xb9, 0xff, 0xd1, 0xbf, 0xa9, 0x11, 0x58, 0x39 } };
 static const EFI_GUID security2_protocol_guid = { 0x94ab2f58, 0x1438, 0x4ef1, {0x91, 0x52, 0x18, 0x94, 0x1a, 0x3a, 0x0e, 0x68 } };
 static const EFI_GUID shim_lock_guid = { 0x605dab50, 0xe046, 0x4300, {0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23} };

 BOOLEAN shim_loaded(void) {
         struct ShimLock *shim_lock;

         return uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID*) &shim_lock_guid, NULL, (VOID**) &shim_lock) == EFI_SUCCESS;
 }

 static BOOLEAN shim_validate(VOID *data, UINT32 size) {
         struct ShimLock *shim_lock;

         if (!data)
                 return FALSE;

         if (uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID*) &shim_lock_guid, NULL, (VOID**) &shim_lock) != EFI_SUCCESS)
                 return FALSE;

         if (!shim_lock)
                 return FALSE;

         if (shim_lock->shim_verify(data, size) == EFI_SUCCESS)
                 return TRUE;

         return FALSE;
 }

 BOOLEAN secure_boot_enabled(void) {
         CHAR8 *b;
         UINTN size;
         BOOLEAN result;

         if (efivar_get_raw(&global_guid, L"SecureBoot", &b, &size) == EFI_SUCCESS) {
                 result = *b > 0;
                 FreePool(b);
                 return result;
         }

         return FALSE;
 }

 /*
  * See the UEFI Platform Initialization manual (Vol2: DXE) for this
  */
 struct _EFI_SECURITY2_PROTOCOL;
 struct _EFI_SECURITY_PROTOCOL;
 struct _EFI_DEVICE_PATH_PROTOCOL;

 typedef struct _EFI_SECURITY2_PROTOCOL EFI_SECURITY2_PROTOCOL;
 typedef struct _EFI_SECURITY_PROTOCOL EFI_SECURITY_PROTOCOL;
 typedef struct _EFI_DEVICE_PATH_PROTOCOL EFI_DEVICE_PATH_PROTOCOL;

 typedef EFI_STATUS (EFIAPI *EFI_SECURITY_FILE_AUTHENTICATION_STATE) (
         const EFI_SECURITY_PROTOCOL *This,
         UINT32 AuthenticationStatus,
         const EFI_DEVICE_PATH_PROTOCOL *File
 );

 typedef EFI_STATUS (EFIAPI *EFI_SECURITY2_FILE_AUTHENTICATION) (
         const EFI_SECURITY2_PROTOCOL *This,
         const EFI_DEVICE_PATH_PROTOCOL *DevicePath,
         VOID *FileBuffer,
         UINTN FileSize,
         BOOLEAN  BootPolicy
 );

 struct _EFI_SECURITY2_PROTOCOL {
         EFI_SECURITY2_FILE_AUTHENTICATION FileAuthentication;
 };

 struct _EFI_SECURITY_PROTOCOL {
         EFI_SECURITY_FILE_AUTHENTICATION_STATE  FileAuthenticationState;
 };

 /* Handle to the original authenticator for security1 protocol */
 static EFI_SECURITY_FILE_AUTHENTICATION_STATE esfas = NULL;

 /* Handle to the original authenticator for security2 protocol */
 static EFI_SECURITY2_FILE_AUTHENTICATION es2fa = NULL;

 /*
  * Perform shim/MOK and Secure Boot authentication on a binary that's already been
  * loaded into memory. This function does the platform SB authentication first
  * but preserves its return value in case of its failure, so that it can be
  * returned in case of a shim/MOK authentication failure. This is done because
  * the SB failure code seems to vary from one implementation to another, and I
  * don't want to interfere with that at this time.
  */
 static EFIAPI EFI_STATUS security2_policy_authentication (const EFI_SECURITY2_PROTOCOL *this,
                                                           const EFI_DEVICE_PATH_PROTOCOL *device_path,
                                                           VOID *file_buffer, UINTN file_size, BOOLEAN boot_policy) {
         EFI_STATUS status;

         /* Chain original security policy */
         status = uefi_call_wrapper(es2fa, 5, this, device_path, file_buffer, file_size, boot_policy);

         /* if OK, don't bother with MOK check */
         if (status == EFI_SUCCESS)
                 return status;

         if (shim_validate(file_buffer, file_size))
                 return EFI_SUCCESS;

         return status;
 }

 /*
  * Perform both shim/MOK and platform Secure Boot authentication. This function loads
  * the file and performs shim/MOK authentication first simply to avoid double loads
  * of Linux kernels, which are much more likely to be shim/MOK-signed than platform-signed,
  * since kernels are big and can take several seconds to load on some computers and
  * filesystems. This also has the effect of returning whatever the platform code is for
  * authentication failure, be it EFI_ACCESS_DENIED, EFI_SECURITY_VIOLATION, or something
  * else. (This seems to vary between implementations.)
  */
 static EFIAPI EFI_STATUS security_policy_authentication (const EFI_SECURITY_PROTOCOL *this, UINT32 authentication_status,
                                                          const EFI_DEVICE_PATH_PROTOCOL *device_path_const) {
         EFI_STATUS status;
         EFI_DEVICE_PATH *dev_path;
         EFI_HANDLE h;
         EFI_FILE *root;
         VOID *file_buffer = NULL;
         UINTN file_size;
         CHAR16 *dev_path_str;

         if (!device_path_const)
                 return EFI_INVALID_PARAMETER;

         dev_path = DuplicateDevicePath((EFI_DEVICE_PATH*) device_path_const);

         status = uefi_call_wrapper(BS->LocateDevicePath, 3, (EFI_GUID*) &simple_fs_guid, &dev_path, &h);
         if (status != EFI_SUCCESS) {
                 FreePool(dev_path);
                 return status;
         }

         /* No need to check return value, this already happend in efi_main() */
         root = LibOpenRoot(h);
         dev_path_str = DevicePathToStr(dev_path);
         FreePool(dev_path);

         file_size = file_read(root, dev_path_str, 0, 0, file_buffer);
         FreePool(dev_path_str);
         uefi_call_wrapper(root->Close, 1, root);

         if (shim_validate(file_buffer, file_size))
                 status = EFI_SUCCESS;

         FreePool(file_buffer);

         /* Try using the platform's native policy.... */
         if (status != EFI_SUCCESS)
                 status = uefi_call_wrapper(esfas, 3, this, authentication_status, device_path_const);

         return status;
 }

 EFI_STATUS security_policy_install(void) {
         EFI_SECURITY_PROTOCOL *security_protocol;
         EFI_SECURITY2_PROTOCOL *security2_protocol = NULL;
         EFI_STATUS status;

         /* Already Installed */
         if (esfas)
                 return EFI_ALREADY_STARTED;

         /*
          * Don't bother with status here.  The call is allowed
          * to fail, since SECURITY2 was introduced in PI 1.2.1
          * If it fails, use security2_protocol == NULL as indicator
          */
         uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID*) &security2_protocol_guid, NULL, (VOID**) &security2_protocol);

         status = uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID*) &security_protocol_guid, NULL, (VOID**) &security_protocol);
          /* This one is mandatory, so there's a serious problem */
         if (status != EFI_SUCCESS)
                 return status;

         if (!security2_protocol) {
                 es2fa = security2_protocol->FileAuthentication;
                 security2_protocol->FileAuthentication = security2_policy_authentication;
         }

         esfas = security_protocol->FileAuthenticationState;
         security_protocol->FileAuthenticationState = security_policy_authentication;

         return EFI_SUCCESS;
 }

 EFI_STATUS security_policy_uninstall(void) {
         EFI_STATUS status;

         if (esfas) {
                 EFI_SECURITY_PROTOCOL *security_protocol;

                 status = uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID*) &security_protocol_guid, NULL, (VOID**) &security_protocol);

                 if (status != EFI_SUCCESS)
                         return status;

                 security_protocol->FileAuthenticationState = esfas;
                 esfas = NULL;
         } else
                 /* nothing installed */
                 return EFI_NOT_STARTED;

         if (es2fa) {
                 EFI_SECURITY2_PROTOCOL *security2_protocol;

                 status = uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID*) &security2_protocol_guid, NULL, (VOID**) &security2_protocol);

                 if (status != EFI_SUCCESS)
                         return status;

                 security2_protocol->FileAuthentication = es2fa;
                 es2fa = NULL;
         }

         return EFI_SUCCESS;
 }
	/*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU Lesser General Public License as published by
	* the Free Software Foundation; either version 2.1 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* Port to systemd-boot
	* Copyright 2017 Max Resch <resch.max@gmail.com>
	*
	* Security Policy Handling
	* Copyright 2012 <James.Bottomley@HansenPartnership.com>
	* https://github.com/mjg59/efitools
	*/

	#include <efi.h>
	#include <efilib.h>

	#include "util.h"
	#include "shim.h"

	/* well known shim lock guid */
	#define SHIM_LOCK_GUID

	struct ShimLock {
	EFI_STATUS __attribute__((sysv_abi)) (shim_verify) (VOID buffer, UINT32 size);

	/* context is actually a struct for the PE header, but it isn't needed so void is sufficient just do define the interface
	* see shim.c/shim.h and PeHeader.h in the github shim repo */
	EFI_STATUS __attribute__((sysv_abi)) (generate_hash) (VOID data, UINT32 datasize, VOID context, UINT8 sha256hash, UINT8 *sha1hash);

	EFI_STATUS __attribute__((sysv_abi)) (read_header) (VOID data, UINT32 datasize, VOID *context);
	};

	static const EFI_GUID simple_fs_guid = SIMPLE_FILE_SYSTEM_PROTOCOL;
	static const EFI_GUID global_guid = EFI_GLOBAL_VARIABLE;

	static const EFI_GUID security_protocol_guid = { 0xa46423e3, 0x4617, 0x49f1, {0xb9, 0xff, 0xd1, 0xbf, 0xa9, 0x11, 0x58, 0x39 } };
	static const EFI_GUID security2_protocol_guid = { 0x94ab2f58, 0x1438, 0x4ef1, {0x91, 0x52, 0x18, 0x94, 0x1a, 0x3a, 0x0e, 0x68 } };
	static const EFI_GUID shim_lock_guid = { 0x605dab50, 0xe046, 0x4300, {0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23} };

	BOOLEAN shim_loaded(void) {
	struct ShimLock *shim_lock;

	return uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID) &shim_lock_guid, NULL, (VOID*) &shim_lock) == EFI_SUCCESS;
	}

	static BOOLEAN shim_validate(VOID *data, UINT32 size) {
	struct ShimLock *shim_lock;

	if (!data)
	return FALSE;

	if (uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID) &shim_lock_guid, NULL, (VOID*) &shim_lock) != EFI_SUCCESS)
	return FALSE;

	if (!shim_lock)
	return FALSE;

	if (shim_lock->shim_verify(data, size) == EFI_SUCCESS)
	return TRUE;

	return FALSE;
	}

	BOOLEAN secure_boot_enabled(void) {
	CHAR8 *b;
	UINTN size;
	BOOLEAN result;

	if (efivar_get_raw(&global_guid, L"SecureBoot", &b, &size) == EFI_SUCCESS) {
	result = *b > 0;
	FreePool(b);
	return result;
	}

	return FALSE;
	}

	/*
	* See the UEFI Platform Initialization manual (Vol2: DXE) for this
	*/
	struct _EFI_SECURITY2_PROTOCOL;
	struct _EFI_SECURITY_PROTOCOL;
	struct _EFI_DEVICE_PATH_PROTOCOL;

	typedef struct _EFI_SECURITY2_PROTOCOL EFI_SECURITY2_PROTOCOL;
	typedef struct _EFI_SECURITY_PROTOCOL EFI_SECURITY_PROTOCOL;
	typedef struct _EFI_DEVICE_PATH_PROTOCOL EFI_DEVICE_PATH_PROTOCOL;

	typedef EFI_STATUS (EFIAPI *EFI_SECURITY_FILE_AUTHENTICATION_STATE) (
	const EFI_SECURITY_PROTOCOL *This,
	UINT32 AuthenticationStatus,
	const EFI_DEVICE_PATH_PROTOCOL *File
	);

	typedef EFI_STATUS (EFIAPI *EFI_SECURITY2_FILE_AUTHENTICATION) (
	const EFI_SECURITY2_PROTOCOL *This,
	const EFI_DEVICE_PATH_PROTOCOL *DevicePath,
	VOID *FileBuffer,
	UINTN FileSize,
	BOOLEAN BootPolicy
	);

	struct _EFI_SECURITY2_PROTOCOL {
	EFI_SECURITY2_FILE_AUTHENTICATION FileAuthentication;
	};

	struct _EFI_SECURITY_PROTOCOL {
	EFI_SECURITY_FILE_AUTHENTICATION_STATE FileAuthenticationState;
	};

	/* Handle to the original authenticator for security1 protocol */
	static EFI_SECURITY_FILE_AUTHENTICATION_STATE esfas = NULL;

	/* Handle to the original authenticator for security2 protocol */
	static EFI_SECURITY2_FILE_AUTHENTICATION es2fa = NULL;

	/*
	* Perform shim/MOK and Secure Boot authentication on a binary that's already been
	* loaded into memory. This function does the platform SB authentication first
	* but preserves its return value in case of its failure, so that it can be
	* returned in case of a shim/MOK authentication failure. This is done because
	* the SB failure code seems to vary from one implementation to another, and I
	* don't want to interfere with that at this time.
	*/
	static EFIAPI EFI_STATUS security2_policy_authentication (const EFI_SECURITY2_PROTOCOL *this,
	const EFI_DEVICE_PATH_PROTOCOL *device_path,
	VOID *file_buffer, UINTN file_size, BOOLEAN boot_policy) {
	EFI_STATUS status;

	/* Chain original security policy */
	status = uefi_call_wrapper(es2fa, 5, this, device_path, file_buffer, file_size, boot_policy);

	/* if OK, don't bother with MOK check */
	if (status == EFI_SUCCESS)
	return status;

	if (shim_validate(file_buffer, file_size))
	return EFI_SUCCESS;

	return status;
	}

	/*
	* Perform both shim/MOK and platform Secure Boot authentication. This function loads
	* the file and performs shim/MOK authentication first simply to avoid double loads
	* of Linux kernels, which are much more likely to be shim/MOK-signed than platform-signed,
	* since kernels are big and can take several seconds to load on some computers and
	* filesystems. This also has the effect of returning whatever the platform code is for
	* authentication failure, be it EFI_ACCESS_DENIED, EFI_SECURITY_VIOLATION, or something
	* else. (This seems to vary between implementations.)
	*/
	static EFIAPI EFI_STATUS security_policy_authentication (const EFI_SECURITY_PROTOCOL *this, UINT32 authentication_status,
	const EFI_DEVICE_PATH_PROTOCOL *device_path_const) {
	EFI_STATUS status;
	EFI_DEVICE_PATH *dev_path;
	EFI_HANDLE h;
	EFI_FILE *root;
	VOID *file_buffer = NULL;
	UINTN file_size;
	CHAR16 *dev_path_str;

	if (!device_path_const)
	return EFI_INVALID_PARAMETER;

	dev_path = DuplicateDevicePath((EFI_DEVICE_PATH*) device_path_const);

	status = uefi_call_wrapper(BS->LocateDevicePath, 3, (EFI_GUID*) &simple_fs_guid, &dev_path, &h);
	if (status != EFI_SUCCESS) {
	FreePool(dev_path);
	return status;
	}

	/* No need to check return value, this already happend in efi_main() */
	root = LibOpenRoot(h);
	dev_path_str = DevicePathToStr(dev_path);
	FreePool(dev_path);

	file_size = file_read(root, dev_path_str, 0, 0, file_buffer);
	FreePool(dev_path_str);
	uefi_call_wrapper(root->Close, 1, root);

	if (shim_validate(file_buffer, file_size))
	status = EFI_SUCCESS;

	FreePool(file_buffer);

	/* Try using the platform's native policy.... */
	if (status != EFI_SUCCESS)
	status = uefi_call_wrapper(esfas, 3, this, authentication_status, device_path_const);

	return status;
	}

	EFI_STATUS security_policy_install(void) {
	EFI_SECURITY_PROTOCOL *security_protocol;
	EFI_SECURITY2_PROTOCOL *security2_protocol = NULL;
	EFI_STATUS status;

	/* Already Installed */
	if (esfas)
	return EFI_ALREADY_STARTED;

	/*
	* Don't bother with status here. The call is allowed
	* to fail, since SECURITY2 was introduced in PI 1.2.1
	* If it fails, use security2_protocol == NULL as indicator
	*/
	uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID) &security2_protocol_guid, NULL, (VOID*) &security2_protocol);

	status = uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID) &security_protocol_guid, NULL, (VOID*) &security_protocol);
	/* This one is mandatory, so there's a serious problem */
	if (status != EFI_SUCCESS)
	return status;

	if (!security2_protocol) {
	es2fa = security2_protocol->FileAuthentication;
	security2_protocol->FileAuthentication = security2_policy_authentication;
	}

	esfas = security_protocol->FileAuthenticationState;
	security_protocol->FileAuthenticationState = security_policy_authentication;

	return EFI_SUCCESS;
	}

	EFI_STATUS security_policy_uninstall(void) {
	EFI_STATUS status;

	if (esfas) {
	EFI_SECURITY_PROTOCOL *security_protocol;

	status = uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID) &security_protocol_guid, NULL, (VOID*) &security_protocol);

	if (status != EFI_SUCCESS)
	return status;

	security_protocol->FileAuthenticationState = esfas;
	esfas = NULL;
	} else
	/* nothing installed */
	return EFI_NOT_STARTED;

	if (es2fa) {
	EFI_SECURITY2_PROTOCOL *security2_protocol;

	status = uefi_call_wrapper(BS->LocateProtocol, 3, (EFI_GUID) &security2_protocol_guid, NULL, (VOID*) &security2_protocol);

	if (status != EFI_SUCCESS)
	return status;

	security2_protocol->FileAuthentication = es2fa;
	es2fa = NULL;
	}

	return EFI_SUCCESS;
	}