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/* $Id: SUPR3HardenedMain-darwin.cpp $ */
/** @file
* VirtualBox Support Library - Hardened main(), posix bits.
*/
/*
* Copyright (C) 2017-2020 Oracle Corporation
*
* This file is part of VirtualBox Open Source Edition (OSE), as
* available from http://www.virtualbox.org. This file is free software;
* you can redistribute it and/or modify it under the terms of the GNU
* General Public License (GPL) as published by the Free Software
* Foundation, in version 2 as it comes in the "COPYING" file of the
* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
* VirtualBox OSE distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#include <VBox/err.h>
#include <VBox/sup.h>
#include <iprt/path.h>
#include <iprt/string.h>
#include <dlfcn.h>
#include <sys/mman.h>
#include <errno.h>
#include <sys/sysctl.h> /* sysctlbyname() */
#include <stdio.h>
#include <stdint.h>
#include <mach-o/dyld.h>
#include "SUPLibInternal.h"
/*********************************************************************************************************************************
* Defined Constants And Macros *
*********************************************************************************************************************************/
/*********************************************************************************************************************************
* Structures and Typedefs *
*********************************************************************************************************************************/
/**
* Interpose table entry.
*/
typedef struct DYLDINTERPOSE
{
/** The symbol address to replace with. */
const void *pvReplacement;
/** The replaced symbol address. */
const void *pvReplacee;
} DYLDINTERPOSE;
/** Pointer to an interposer table entry. */
typedef DYLDINTERPOSE *PDYLDINTERPOSE;
/** Pointer to a const interposer table entry. */
typedef const DYLDINTERPOSE *PCDYLDINTERPOSE;
/** @sa dyld_dynamic_interpose(). */
typedef const mach_header * FNDYLDDYNAMICINTERPOSE(const struct mach_header* mh, PCDYLDINTERPOSE paSym, size_t cSyms);
typedef FNDYLDDYNAMICINTERPOSE *PFNDYLDDYNAMICINTERPOSE;
/** @sa dlopen(). */
typedef void *FNDLOPEN(const char *path, int mode);
typedef FNDLOPEN *PFNDLOPEN;
/*********************************************************************************************************************************
* Internal Functions *
*********************************************************************************************************************************/
extern "C" void _dyld_register_func_for_add_image(void (*func)(const struct mach_header* mh, intptr_t vmaddr_slide));
static void * supR3HardenedDarwinDlopenInterpose(const char *path, int mode);
/*********************************************************************************************************************************
* Global Variables *
*********************************************************************************************************************************/
/** Flag whether macOS 11.x (BigSur) was detected. */
static bool g_fMacOs11 = false;
/** Resolved dyld_dynamic_interpose() value. */
static PFNDYLDDYNAMICINTERPOSE g_pfnDyldDynamicInterpose = NULL;
/** Pointer to the real dlopen() function used from the interposer when verification succeeded. */
static PFNDLOPEN g_pfnDlopenReal = NULL;
/**
* The interposer table.
*/
static const DYLDINTERPOSE g_aInterposers[] =
{
{ (const void *)(uintptr_t)&supR3HardenedDarwinDlopenInterpose, (const void *)(uintptr_t)&dlopen }
};
/**
* dlopen() interposer which verifies that the path to be loaded meets the criteria for hardened builds.
*
* @sa dlopen() man page.
*/
static void * supR3HardenedDarwinDlopenInterpose(const char *path, int mode)
{
/*
* Giving NULL as the filename indicates opening the main program which is fine
* We are already loaded and executing after all.
*
* Filenames without any path component (whether absolute or relative) are allowed
* unconditionally too as the loader will only search the default paths configured by root.
*/
if ( path
&& strchr(path, '/') != NULL)
{
int rc = VINF_SUCCESS;
/*
* Starting with macOS 11.0 (BigSur) system provided libraries
* under /System/Libraries are not stored on the filesystem anymore
* but in a dynamic linker cache. The integrity of the linker cache
* is maintained by the system and dyld. Our verification code fails because
* it can't find the file.
* The obvious solution is to exclude paths starting with /System/Libraries
* when we run on BigSur. Other paths are still subject to verification.
*/
if ( !g_fMacOs11
|| strncmp(path, RT_STR_TUPLE("/System/Library")))
rc = supR3HardenedVerifyFileFollowSymlinks(path, RTHCUINTPTR_MAX, true /* fMaybe3rdParty */,
NULL /* pErrInfo */);
if (RT_FAILURE(rc))
return NULL;
}
return g_pfnDlopenReal(path, mode);
}
/**
* Callback to get notified of new images being loaded to be able to apply our dlopn() interposer.
*
* @returns nothing.
* @param mh Pointer to the mach header of the loaded image.
* @param vmaddr_slide The slide value for ASLR.
*/
static DECLCALLBACK(void) supR3HardenedDarwinAddImage(const struct mach_header* mh, intptr_t vmaddr_slide)
{
RT_NOREF(vmaddr_slide);
g_pfnDyldDynamicInterpose((const struct mach_header*)mh, &g_aInterposers[0], RT_ELEMENTS(g_aInterposers));
}
/**
* Hardening initialization for macOS hosts.
*
* @returns nothing.
*
* @note Doesn't return on error.
*/
DECLHIDDEN(void) supR3HardenedDarwinInit(void)
{
/*
* Check whether we are running on macOS BigSur by checking kern.osproductversion
* available since some point in 2018.
*/
char szVers[256]; RT_ZERO(szVers);
size_t cbVers = sizeof(szVers);
int rc = sysctlbyname("kern.osproductversion", &szVers[0], &cbVers, NULL, 0);
if ( !rc
&& !memcmp(&szVers[0], RT_STR_TUPLE("10.16")))
g_fMacOs11 = true;
/* Saved to call real dlopen() later on, as we will interpose dlopen() from the main binary in the next step as well. */
g_pfnDlopenReal = (PFNDLOPEN)dlsym(RTLD_DEFAULT, "dlopen");
g_pfnDyldDynamicInterpose = (PFNDYLDDYNAMICINTERPOSE)dlsym(RTLD_DEFAULT, "dyld_dynamic_interpose");
if (!g_pfnDyldDynamicInterpose)
supR3HardenedFatalMsg("supR3HardenedDarwinInit", kSupInitOp_Integrity, VERR_SYMBOL_NOT_FOUND,
"Failed to find dyld_dynamic_interpose()");
/*
* The following will causes our add image notification to be called for all images loaded so far.
* The callback will set up the interposer.
*/
_dyld_register_func_for_add_image(supR3HardenedDarwinAddImage);
}
/*
* assert.cpp
*
* ASSUMES working DECLHIDDEN or there will be symbol confusion!
*/
RTDATADECL(char) g_szRTAssertMsg1[1024];
RTDATADECL(char) g_szRTAssertMsg2[4096];
RTDATADECL(const char * volatile) g_pszRTAssertExpr;
RTDATADECL(const char * volatile) g_pszRTAssertFile;
RTDATADECL(uint32_t volatile) g_u32RTAssertLine;
RTDATADECL(const char * volatile) g_pszRTAssertFunction;
RTDECL(bool) RTAssertMayPanic(void)
{
return true;
}
RTDECL(void) RTAssertMsg1(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction)
{
/*
* Fill in the globals.
*/
g_pszRTAssertExpr = pszExpr;
g_pszRTAssertFile = pszFile;
g_pszRTAssertFunction = pszFunction;
g_u32RTAssertLine = uLine;
snprintf(g_szRTAssertMsg1, sizeof(g_szRTAssertMsg1),
"\n!!Assertion Failed!!\n"
"Expression: %s\n"
"Location : %s(%u) %s\n",
pszExpr, pszFile, uLine, pszFunction);
}
RTDECL(void) RTAssertMsg2V(const char *pszFormat, va_list va)
{
vsnprintf(g_szRTAssertMsg2, sizeof(g_szRTAssertMsg2), pszFormat, va);
if (g_enmSupR3HardenedMainState < SUPR3HARDENEDMAINSTATE_CALLED_TRUSTED_MAIN)
supR3HardenedFatalMsg(g_pszRTAssertExpr, kSupInitOp_Misc, VERR_INTERNAL_ERROR,
"%s%s", g_szRTAssertMsg1, g_szRTAssertMsg2);
else
supR3HardenedError(VERR_INTERNAL_ERROR, false/*fFatal*/, "%s%s", g_szRTAssertMsg1, g_szRTAssertMsg2);
}
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