/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/blockcancel.internal.h"
#include "libc/calls/calls.h"
#include "libc/calls/cp.internal.h"
#include "libc/calls/internal.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/struct/stat.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/fmt/itoa.h"
#include "libc/intrin/asan.internal.h"
#include "libc/intrin/describeflags.internal.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/safemacros.internal.h"
#include "libc/intrin/strace.internal.h"
#include "libc/intrin/weaken.h"
#include "libc/limits.h"
#include "libc/proc/execve.internal.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/f.h"
#include "libc/sysv/consts/fd.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/mfd.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/consts/prot.h"
#include "libc/sysv/consts/shm.h"
#include "libc/sysv/errfuns.h"
static bool IsAPEFd(const int fd) {
char buf[8];
return (sys_pread(fd, buf, 8, 0, 0) == 8) && IsApeLoadable(buf);
}
static int fexecve_impl(const int fd, char *const argv[], char *const envp[]) {
int rc;
if (IsLinux()) {
char path[14 + 12];
FormatInt32(stpcpy(path, "/proc/self/fd/"), fd);
rc = __sys_execve(path, argv, envp);
} else if (IsFreebsd()) {
rc = sys_fexecve(fd, argv, envp);
} else {
rc = enosys();
}
return rc;
}
typedef enum {
PTF_NUM = 1 << 0,
PTF_NUM2 = 1 << 1,
PTF_NUM3 = 1 << 2,
PTF_ANY = 1 << 3
} PTF_PARSE;
static bool ape_to_elf(void *ape, const size_t apesize) {
static const char printftok[] = "printf '";
static const size_t printftoklen = sizeof(printftok) - 1;
const char *tok = memmem(ape, apesize, printftok, printftoklen);
if (tok) {
tok += printftoklen;
uint8_t *dest = ape;
PTF_PARSE state = PTF_ANY;
uint8_t value = 0;
for (; tok < (const char *)(dest + apesize); tok++) {
if ((state & (PTF_NUM | PTF_NUM2 | PTF_NUM3)) &&
(*tok >= '0' && *tok <= '7')) {
value = (value << 3) | (*tok - '0');
state <<= 1;
if (state & PTF_ANY) {
*dest++ = value;
}
} else if (state & PTF_NUM) {
break;
} else {
if (state & (PTF_NUM2 | PTF_NUM3)) {
*dest++ = value;
}
if (*tok == '\\') {
state = PTF_NUM;
value = 0;
} else if (*tok == '\'') {
return true;
} else {
*dest++ = *tok;
state = PTF_ANY;
}
}
}
}
errno = ENOEXEC;
return false;
}
/**
* Creates a memfd and copies fd to it.
*
* This does an inplace conversion of APE to ELF when detected!!!!
*/
static int fd_to_mem_fd(const int infd, char *path) {
if ((!IsLinux() && !IsFreebsd()) || !_weaken(mmap) || !_weaken(munmap)) {
return enosys();
}
struct stat st;
if (fstat(infd, &st) == -1) {
return -1;
}
int fd;
if (IsLinux()) {
fd = sys_memfd_create(__func__, MFD_CLOEXEC);
} else if (IsFreebsd()) {
fd = sys_shm_open(SHM_ANON, O_CREAT | O_RDWR, 0);
} else {
return enosys();
}
if (fd == -1) {
return -1;
}
void *space;
if ((sys_ftruncate(fd, st.st_size, st.st_size) != -1) &&
((space = _weaken(mmap)(0, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED,
fd, 0)) != MAP_FAILED)) {
ssize_t readRc;
readRc = pread(infd, space, st.st_size, 0);
bool success = readRc != -1;
if (success && (st.st_size > 8) && IsApeLoadable(space)) {
int flags = fcntl(fd, F_GETFD);
if ((success = (flags != -1) &&
(fcntl(fd, F_SETFD, flags & (~FD_CLOEXEC)) != -1) &&
ape_to_elf(space, st.st_size))) {
const int newfd = fcntl(fd, F_DUPFD, 9001);
if (newfd != -1) {
close(fd);
fd = newfd;
}
}
}
const int e = errno;
if ((_weaken(munmap)(space, st.st_size) != -1) && success) {
if (path) {
FormatInt32(stpcpy(path, "COSMOPOLITAN_INIT_ZIPOS="), fd);
}
unassert(readRc == st.st_size);
return fd;
} else if (!success) {
errno = e;
}
}
const int e = errno;
close(fd);
errno = e;
return -1;
}
/**
* Executes binary executable at file descriptor.
*
* This is only supported on Linux and FreeBSD. APE binaries are
* supported. Zipos is supported. Zipos fds or FD_CLOEXEC APE fds or
* fds that fail fexecve with ENOEXEC are copied to a new memfd (with
* in-memory APE to ELF conversion) and fexecve is (re)attempted.
*
* @param fd is opened executable and current file position is ignored
* @return doesn't return on success, otherwise -1 w/ errno
* @raise ENOEXEC if file at `fd` isn't an assimilated ELF executable
* @raise ENOSYS on Windows, XNU, OpenBSD, NetBSD, and Metal
*/
int fexecve(int fd, char *const argv[], char *const envp[]) {
int rc = 0;
if (!argv || !envp ||
(IsAsan() &&
(!__asan_is_valid_strlist(argv) || !__asan_is_valid_strlist(envp)))) {
rc = efault();
} else {
STRACE("fexecve(%d, %s, %s) → ...", fd, DescribeStringList(argv),
DescribeStringList(envp));
int savedErr = 0;
do {
if (!IsLinux() && !IsFreebsd()) {
rc = enosys();
break;
}
if (!__isfdkind(fd, kFdZip)) {
bool memfdReq;
BLOCK_SIGNALS;
BLOCK_CANCELATION;
strace_enabled(-1);
memfdReq = ((rc = fcntl(fd, F_GETFD)) != -1) && (rc & FD_CLOEXEC) &&
IsAPEFd(fd);
strace_enabled(+1);
ALLOW_CANCELATION;
ALLOW_SIGNALS;
if (rc == -1) {
break;
} else if (!memfdReq) {
fexecve_impl(fd, argv, envp);
if (errno != ENOEXEC) {
break;
}
savedErr = ENOEXEC;
}
}
int newfd;
char *path = alloca(PATH_MAX);
BLOCK_SIGNALS;
BLOCK_CANCELATION;
strace_enabled(-1);
newfd = fd_to_mem_fd(fd, path);
strace_enabled(+1);
ALLOW_CANCELATION;
ALLOW_SIGNALS;
if (newfd == -1) {
break;
}
size_t numenvs;
for (numenvs = 0; envp[numenvs];)
++numenvs;
// const size_t desenvs = min(500, max(numenvs + 1, 2));
static _Thread_local char *envs[500];
memcpy(envs, envp, numenvs * sizeof(char *));
envs[numenvs] = path;
envs[numenvs + 1] = NULL;
fexecve_impl(newfd, argv, envs);
if (!savedErr) {
savedErr = errno;
}
BLOCK_SIGNALS;
BLOCK_CANCELATION;
strace_enabled(-1);
close(newfd);
strace_enabled(+1);
ALLOW_CANCELATION;
ALLOW_SIGNALS;
} while (0);
if (savedErr) {
errno = savedErr;
}
rc = -1;
}
STRACE("fexecve(%d) failed %d% m", fd, rc);
return rc;
}