darling-dyld/dyld3/ClosureFileSystemPhysical.cpp
2023-04-29 11:24:58 -07:00

311 lines
11 KiB
C++

/*
* Copyright (c) 2017 Apple Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
#include "ClosureFileSystemPhysical.h"
#include <TargetConditionals.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/errno.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <mach/mach.h>
#if !TARGET_OS_SIMULATOR && !TARGET_OS_DRIVERKIT
#include <sandbox.h>
#include <sandbox/private.h>
#endif
#include <TargetConditionals.h>
#include "MachOFile.h"
#include "MachOAnalyzer.h"
using dyld3::closure::FileSystemPhysical;
bool FileSystemPhysical::getRealPath(const char possiblePath[MAXPATHLEN], char realPath[MAXPATHLEN]) const {
__block bool success = false;
// first pass: open file and ask kernel for canonical path
forEachPath(possiblePath, ^(const char* aPath, unsigned prefixLen, bool& stop) {
int fd = dyld3::open(aPath, O_RDONLY, 0);
if ( fd != -1 ) {
char tempPath[MAXPATHLEN];
success = (fcntl(fd, F_GETPATH, tempPath) == 0);
::close(fd);
if ( success ) {
// if prefix was used, remove it
strcpy(realPath, &tempPath[prefixLen]);
}
stop = true;
}
});
if (success)
return success;
// second pass: file does not exist but may be a symlink to a non-existent file
// This is only for use on-device on platforms where dylibs are removed
if ( _overlayPath == nullptr && _rootPath == nullptr ) {
realpath(possiblePath, realPath);
int realpathErrno = errno;
// If realpath() resolves to a path which does not exist on disk, errno is set to ENOENT
success = (realpathErrno == ENOENT) || (realpathErrno == 0);
}
return success;
}
static bool sandboxBlocked(const char* path, const char* kind)
{
#if TARGET_OS_SIMULATOR || TARGET_OS_DRIVERKIT
// sandbox calls not yet supported in dyld_sim
return false;
#else
sandbox_filter_type filter = (sandbox_filter_type)(SANDBOX_FILTER_PATH | SANDBOX_CHECK_NO_REPORT);
return ( sandbox_check(getpid(), kind, filter, path) > 0 );
#endif
}
static bool sandboxBlockedMmap(const char* path)
{
return sandboxBlocked(path, "file-map-executable");
}
static bool sandboxBlockedOpen(const char* path)
{
return sandboxBlocked(path, "file-read-data");
}
static bool sandboxBlockedStat(const char* path)
{
return sandboxBlocked(path, "file-read-metadata");
}
void FileSystemPhysical::forEachPath(const char* path, void (^handler)(const char* fullPath, unsigned prefixLen, bool& stop)) const
{
bool stop = false;
char altPath[PATH_MAX];
if ( _overlayPath != nullptr ) {
strlcpy(altPath, _overlayPath, PATH_MAX);
strlcat(altPath, path, PATH_MAX);
handler(altPath, (unsigned)strlen(_overlayPath), stop);
if ( stop )
return;
}
if ( _rootPath != nullptr ) {
strlcpy(altPath, _rootPath, PATH_MAX);
if ( path[0] != '/' )
strlcat(altPath, "/", PATH_MAX);
strlcat(altPath, path, PATH_MAX);
handler(altPath, (unsigned)strlen(_rootPath), stop);
if ( stop )
return;
}
else {
handler(path, 0, stop);
}
}
static bool isFileRelativePath(const char* path)
{
if ( path[0] == '/' )
return false;
if ( path[0] != '.' )
return true;
if ( path[1] == '/' )
return true;
if ( (path[1] == '.') && (path[2] == '/') )
return true;
return false;
}
// Returns true on success. If an error occurs the given callback will be called with the reason.
// On success, info is filled with info about the loaded file. If the path supplied includes a symlink,
// the supplier realerPath is filled in with the real path of the file, otherwise it is set to the empty string.
bool FileSystemPhysical::loadFile(const char* path, LoadedFileInfo& info, char realerPath[MAXPATHLEN], void (^error)(const char* format, ...)) const {
if ( !_allowRelativePaths && isFileRelativePath(path) ) {
error("relative file paths not allowed '%s'", path);
return false;
}
// open file
__block int fd;
__block struct stat statBuf;
forEachPath(path, ^(const char* aPath, unsigned prefixLen, bool& stop) {
fd = dyld3::open(aPath, O_RDONLY, 0);
if ( fd == -1 ) {
int openErrno = errno;
if ( (openErrno == EPERM) && sandboxBlockedOpen(path) )
error("file system sandbox blocked open(\"%s\", O_RDONLY)", path);
else if ( (openErrno != ENOENT) && (openErrno != ENOTDIR) )
error("open(\"%s\", O_RDONLY) failed with errno=%d", path, openErrno);
}
else {
// get file info
#if TARGET_OS_SIMULATOR
if ( ::stat(aPath, &statBuf) != 0 ) {
#else
if ( ::fstat(fd, &statBuf) != 0 ) {
#endif
int statErr = errno;
if ( (statErr == EPERM) && sandboxBlockedStat(path) )
error("file system sandbox blocked stat(\"%s\")", path);
else
error("stat(\"%s\") failed with errno=%d", path, errno);
::close(fd);
fd = -1;
}
else {
// Get the realpath of the file if it is a symlink
char tempPath[MAXPATHLEN];
if ( fcntl(fd, F_GETPATH, tempPath) == 0 ) {
const char* realPathWithin = &tempPath[prefixLen];
// Don't set the realpath if it is just the same as the regular path
if ( strcmp(path, realPathWithin) == 0 ) {
// zero out realerPath if path is fine as-is
// <rdar://45018392> don't trash input 'path' if realerPath is same buffer as path
if ( realerPath != path )
realerPath[0] = '\0';
}
else
strcpy(realerPath, realPathWithin);
stop = true;
}
else {
error("Could not get real path for \"%s\"\n", path);
::close(fd);
fd = -1;
}
}
}
});
if ( fd == -1 )
return false;
// only regular files can be loaded
if ( !S_ISREG(statBuf.st_mode) ) {
error("not a file for %s", path);
::close(fd);
return false;
}
// mach-o files must be at list one page in size
if ( statBuf.st_size < 4096 ) {
error("file too short %s", path);
::close(fd);
return false;
}
info.fileContent = nullptr;
info.fileContentLen = statBuf.st_size;
info.sliceOffset = 0;
info.sliceLen = statBuf.st_size;
info.isOSBinary = false;
info.inode = statBuf.st_ino;
info.mtime = statBuf.st_mtime;
info.path = path;
// mmap() whole file
void* wholeFile = ::mmap(nullptr, (size_t)statBuf.st_size, PROT_READ, MAP_PRIVATE|MAP_RESILIENT_CODESIGN, fd, 0);
if ( wholeFile == MAP_FAILED ) {
int mmapErr = errno;
if ( mmapErr == EPERM ) {
if ( sandboxBlockedMmap(path) )
error("file system sandbox blocked mmap() of '%s'", path);
else
error("code signing blocked mmap() of '%s'", path);
}
else {
error("mmap() failed with errno=%d for %s", errno, path);
}
::close(fd);
return false;
}
info.fileContent = wholeFile;
// if this is an arm64e mach-o or a fat file with an arm64e slice we need to record if it is an OS binary
#if TARGET_OS_OSX && __arm64e__
const MachOAnalyzer* ma = (MachOAnalyzer*)wholeFile;
if ( ma->hasMachOMagic() ) {
if ( (ma->cputype == CPU_TYPE_ARM64) && ((ma->cpusubtype & ~CPU_SUBTYPE_MASK) == CPU_SUBTYPE_ARM64E) ) {
if ( ma->isOSBinary(fd, 0, info.fileContentLen) )
info.isOSBinary = true;
}
}
else if ( const FatFile* fat = FatFile::isFatFile(wholeFile) ) {
Diagnostics diag;
fat->forEachSlice(diag, info.fileContentLen, ^(uint32_t sliceCpuType, uint32_t sliceCpuSubType, const void* sliceStart, uint64_t sliceSize, bool& stop) {
if ( (sliceCpuType == CPU_TYPE_ARM64) && ((sliceCpuSubType & ~CPU_SUBTYPE_MASK) == CPU_SUBTYPE_ARM64E) ) {
uint64_t sliceOffset = (uint8_t*)sliceStart-(uint8_t*)wholeFile;
const MachOAnalyzer* sliceMA = (MachOAnalyzer*)((uint8_t*)wholeFile + sliceOffset);
if ( sliceMA->isOSBinary(fd, sliceOffset, sliceSize) )
info.isOSBinary = true;
}
});
}
#endif
// Set unmap as the unload method.
info.unload = [](const LoadedFileInfo& info) {
::munmap((void*)info.fileContent, (size_t)info.fileContentLen);
};
::close(fd);
return true;
}
void FileSystemPhysical::unloadFile(const LoadedFileInfo& info) const {
if (info.unload)
info.unload(info);
}
void FileSystemPhysical::unloadPartialFile(LoadedFileInfo& info, uint64_t keepStartOffset, uint64_t keepLength) const {
// Unmap from 0..keepStartOffset and (keepStartOffset+keepLength)..info.fileContentLen
if (keepStartOffset)
::munmap((void*)info.fileContent, (size_t)trunc_page(keepStartOffset));
if ((keepStartOffset + keepLength) != info.fileContentLen) {
uintptr_t start = round_page((uintptr_t)info.fileContent + keepStartOffset + keepLength);
uintptr_t end = (uintptr_t)info.fileContent + info.fileContentLen;
::munmap((void*)start, end - start);
}
info.fileContent = (const void*)((char*)info.fileContent + keepStartOffset);
info.fileContentLen = keepLength;
}
bool FileSystemPhysical::fileExists(const char* path, uint64_t* inode, uint64_t* mtime,
bool* issetuid, bool* inodesMatchRuntime) const {
__block bool result = false;
forEachPath(path, ^(const char* aPath, unsigned prefixLen, bool& stop) {
struct stat statBuf;
if ( dyld3::stat(aPath, &statBuf) == 0 ) {
if (inode)
*inode = statBuf.st_ino;
if (mtime)
*mtime = statBuf.st_mtime;
if (issetuid)
*issetuid = (statBuf.st_mode & (S_ISUID|S_ISGID));
if (inodesMatchRuntime)
*inodesMatchRuntime = true;
stop = true;
result = true;
}
});
return result;
}