417 lines
10 KiB
C
Executable file
417 lines
10 KiB
C
Executable file
/* $OpenBSD: getentropy_osx.c,v 1.13 2020/05/17 14:44:20 deraadt Exp $ */
|
|
|
|
/*
|
|
* Copyright (c) 2014 Theo de Raadt <deraadt@openbsd.org>
|
|
* Copyright (c) 2014 Bob Beck <beck@obtuse.com>
|
|
*
|
|
* Permission to use, copy, modify, and 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.
|
|
*
|
|
* Emulation of getentropy(2) as documented at:
|
|
* http://man.openbsd.org/getentropy.2
|
|
*/
|
|
|
|
#include <TargetConditionals.h>
|
|
#include <sys/types.h>
|
|
#include <sys/param.h>
|
|
#include <sys/ioctl.h>
|
|
#include <sys/resource.h>
|
|
#include <sys/syscall.h>
|
|
#include <sys/sysctl.h>
|
|
#include <sys/statvfs.h>
|
|
#include <sys/socket.h>
|
|
#include <sys/mount.h>
|
|
#include <sys/mman.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/time.h>
|
|
#include <stdlib.h>
|
|
#include <stdint.h>
|
|
#include <stdio.h>
|
|
#include <termios.h>
|
|
#include <fcntl.h>
|
|
#include <signal.h>
|
|
#include <string.h>
|
|
#include <errno.h>
|
|
#include <unistd.h>
|
|
#include <time.h>
|
|
#include <mach/mach_time.h>
|
|
#include <mach/mach_host.h>
|
|
#include <mach/host_info.h>
|
|
#if TARGET_OS_OSX
|
|
#include <sys/socketvar.h>
|
|
#include <sys/vmmeter.h>
|
|
#endif
|
|
#include <netinet/in.h>
|
|
#include <netinet/tcp.h>
|
|
#if TARGET_OS_OSX
|
|
#include <netinet/udp.h>
|
|
#include <netinet/ip_var.h>
|
|
#include <netinet/tcp_var.h>
|
|
#include <netinet/udp_var.h>
|
|
#endif
|
|
#include <CommonCrypto/CommonDigest.h>
|
|
#define SHA512_Update(a, b, c) (CC_SHA512_Update((a), (b), (c)))
|
|
#define SHA512_Init(xxx) (CC_SHA512_Init((xxx)))
|
|
#define SHA512_Final(xxx, yyy) (CC_SHA512_Final((xxx), (yyy)))
|
|
#define SHA512_CTX CC_SHA512_CTX
|
|
#define SHA512_DIGEST_LENGTH CC_SHA512_DIGEST_LENGTH
|
|
|
|
#define REPEAT 5
|
|
#define MINIMUM(a, b) (((a) < (b)) ? (a) : (b))
|
|
|
|
#define HX(a, b) \
|
|
do { \
|
|
if ((a)) \
|
|
HD(errno); \
|
|
else \
|
|
HD(b); \
|
|
} while (0)
|
|
|
|
#define HR(x, l) (SHA512_Update(&ctx, (char *)(x), (l)))
|
|
#define HD(x) (SHA512_Update(&ctx, (char *)&(x), sizeof (x)))
|
|
#define HF(x) (SHA512_Update(&ctx, (char *)&(x), sizeof (void*)))
|
|
|
|
int getentropy(void *buf, size_t len);
|
|
|
|
static int getentropy_urandom(void *buf, size_t len);
|
|
static int getentropy_fallback(void *buf, size_t len);
|
|
|
|
int
|
|
getentropy(void *buf, size_t len)
|
|
{
|
|
int ret = -1;
|
|
|
|
if (len > 256) {
|
|
errno = EIO;
|
|
return (-1);
|
|
}
|
|
|
|
/*
|
|
* Try to get entropy with /dev/urandom
|
|
*
|
|
* This can fail if the process is inside a chroot or if file
|
|
* descriptors are exhausted.
|
|
*/
|
|
ret = getentropy_urandom(buf, len);
|
|
if (ret != -1)
|
|
return (ret);
|
|
|
|
/*
|
|
* Entropy collection via /dev/urandom and sysctl have failed.
|
|
*
|
|
* No other API exists for collecting entropy, and we have
|
|
* no failsafe way to get it on OSX that is not sensitive
|
|
* to resource exhaustion.
|
|
*
|
|
* We have very few options:
|
|
* - Even syslog_r is unsafe to call at this low level, so
|
|
* there is no way to alert the user or program.
|
|
* - Cannot call abort() because some systems have unsafe
|
|
* corefiles.
|
|
* - Could raise(SIGKILL) resulting in silent program termination.
|
|
* - Return EIO, to hint that arc4random's stir function
|
|
* should raise(SIGKILL)
|
|
* - Do the best under the circumstances....
|
|
*
|
|
* This code path exists to bring light to the issue that OSX
|
|
* does not provide a failsafe API for entropy collection.
|
|
*
|
|
* We hope this demonstrates that OSX should consider
|
|
* providing a new failsafe API which works in a chroot or
|
|
* when file descriptors are exhausted.
|
|
*/
|
|
#undef FAIL_INSTEAD_OF_TRYING_FALLBACK
|
|
#ifdef FAIL_INSTEAD_OF_TRYING_FALLBACK
|
|
raise(SIGKILL);
|
|
#endif
|
|
ret = getentropy_fallback(buf, len);
|
|
if (ret != -1)
|
|
return (ret);
|
|
|
|
errno = EIO;
|
|
return (ret);
|
|
}
|
|
|
|
static int
|
|
getentropy_urandom(void *buf, size_t len)
|
|
{
|
|
struct stat st;
|
|
size_t i;
|
|
int fd, flags;
|
|
int save_errno = errno;
|
|
|
|
start:
|
|
|
|
flags = O_RDONLY;
|
|
#ifdef O_NOFOLLOW
|
|
flags |= O_NOFOLLOW;
|
|
#endif
|
|
#ifdef O_CLOEXEC
|
|
flags |= O_CLOEXEC;
|
|
#endif
|
|
fd = open("/dev/urandom", flags, 0);
|
|
if (fd == -1) {
|
|
if (errno == EINTR)
|
|
goto start;
|
|
goto nodevrandom;
|
|
}
|
|
#ifndef O_CLOEXEC
|
|
fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
|
|
#endif
|
|
|
|
/* Lightly verify that the device node looks sane */
|
|
if (fstat(fd, &st) == -1 || !S_ISCHR(st.st_mode)) {
|
|
close(fd);
|
|
goto nodevrandom;
|
|
}
|
|
for (i = 0; i < len; ) {
|
|
size_t wanted = len - i;
|
|
ssize_t ret = read(fd, (char *)buf + i, wanted);
|
|
|
|
if (ret == -1) {
|
|
if (errno == EAGAIN || errno == EINTR)
|
|
continue;
|
|
close(fd);
|
|
goto nodevrandom;
|
|
}
|
|
i += ret;
|
|
}
|
|
close(fd);
|
|
errno = save_errno;
|
|
return (0); /* satisfied */
|
|
nodevrandom:
|
|
errno = EIO;
|
|
return (-1);
|
|
}
|
|
|
|
#if TARGET_OS_OSX
|
|
static int tcpmib[] = { CTL_NET, AF_INET, IPPROTO_TCP, TCPCTL_STATS };
|
|
static int udpmib[] = { CTL_NET, AF_INET, IPPROTO_UDP, UDPCTL_STATS };
|
|
static int ipmib[] = { CTL_NET, AF_INET, IPPROTO_IP, IPCTL_STATS };
|
|
#endif
|
|
static int kmib[] = { CTL_KERN, KERN_USRSTACK };
|
|
static int hwmib[] = { CTL_HW, HW_USERMEM };
|
|
|
|
static int
|
|
getentropy_fallback(void *buf, size_t len)
|
|
{
|
|
uint8_t results[SHA512_DIGEST_LENGTH];
|
|
int save_errno = errno, e, pgs = getpagesize(), faster = 0, repeat;
|
|
static int cnt;
|
|
struct timespec ts;
|
|
struct timeval tv;
|
|
struct rusage ru;
|
|
sigset_t sigset;
|
|
struct stat st;
|
|
SHA512_CTX ctx;
|
|
static pid_t lastpid;
|
|
pid_t pid;
|
|
size_t i, ii, m;
|
|
char *p;
|
|
#if TARGET_OS_OSX
|
|
struct tcpstat tcpstat;
|
|
struct udpstat udpstat;
|
|
struct ipstat ipstat;
|
|
#endif
|
|
u_int64_t mach_time;
|
|
unsigned int idata;
|
|
void *addr;
|
|
|
|
pid = getpid();
|
|
if (lastpid == pid) {
|
|
faster = 1;
|
|
repeat = 2;
|
|
} else {
|
|
faster = 0;
|
|
lastpid = pid;
|
|
repeat = REPEAT;
|
|
}
|
|
for (i = 0; i < len; ) {
|
|
int j;
|
|
SHA512_Init(&ctx);
|
|
for (j = 0; j < repeat; j++) {
|
|
HX((e = gettimeofday(&tv, NULL)) == -1, tv);
|
|
if (e != -1) {
|
|
cnt += (int)tv.tv_sec;
|
|
cnt += (int)tv.tv_usec;
|
|
}
|
|
|
|
mach_time = mach_absolute_time();
|
|
HD(mach_time);
|
|
|
|
ii = sizeof(addr);
|
|
HX(sysctl(kmib, sizeof(kmib) / sizeof(kmib[0]),
|
|
&addr, &ii, NULL, 0) == -1, addr);
|
|
|
|
ii = sizeof(idata);
|
|
HX(sysctl(hwmib, sizeof(hwmib) / sizeof(hwmib[0]),
|
|
&idata, &ii, NULL, 0) == -1, idata);
|
|
|
|
#if TARGET_OS_OSX
|
|
ii = sizeof(tcpstat);
|
|
HX(sysctl(tcpmib, sizeof(tcpmib) / sizeof(tcpmib[0]),
|
|
&tcpstat, &ii, NULL, 0) == -1, tcpstat);
|
|
|
|
ii = sizeof(udpstat);
|
|
HX(sysctl(udpmib, sizeof(udpmib) / sizeof(udpmib[0]),
|
|
&udpstat, &ii, NULL, 0) == -1, udpstat);
|
|
|
|
ii = sizeof(ipstat);
|
|
HX(sysctl(ipmib, sizeof(ipmib) / sizeof(ipmib[0]),
|
|
&ipstat, &ii, NULL, 0) == -1, ipstat);
|
|
#endif
|
|
|
|
HX((pid = getpid()) == -1, pid);
|
|
HX((pid = getsid(pid)) == -1, pid);
|
|
HX((pid = getppid()) == -1, pid);
|
|
HX((pid = getpgid(0)) == -1, pid);
|
|
HX((e = getpriority(0, 0)) == -1, e);
|
|
|
|
if (!faster) {
|
|
ts.tv_sec = 0;
|
|
ts.tv_nsec = 1;
|
|
(void) nanosleep(&ts, NULL);
|
|
}
|
|
|
|
HX(sigpending(&sigset) == -1, sigset);
|
|
HX(sigprocmask(SIG_BLOCK, NULL, &sigset) == -1,
|
|
sigset);
|
|
|
|
HF(getentropy); /* an addr in this library */
|
|
HF(printf); /* an addr in libc */
|
|
p = (char *)&p;
|
|
HD(p); /* an addr on stack */
|
|
p = (char *)&errno;
|
|
HD(p); /* the addr of errno */
|
|
|
|
if (i == 0) {
|
|
struct sockaddr_storage ss;
|
|
struct statvfs stvfs;
|
|
struct termios tios;
|
|
struct statfs stfs;
|
|
socklen_t ssl;
|
|
off_t off;
|
|
|
|
/*
|
|
* Prime-sized mappings encourage fragmentation;
|
|
* thus exposing some address entropy.
|
|
*/
|
|
struct mm {
|
|
size_t npg;
|
|
void *p;
|
|
} mm[] = {
|
|
{ 17, MAP_FAILED }, { 3, MAP_FAILED },
|
|
{ 11, MAP_FAILED }, { 2, MAP_FAILED },
|
|
{ 5, MAP_FAILED }, { 3, MAP_FAILED },
|
|
{ 7, MAP_FAILED }, { 1, MAP_FAILED },
|
|
{ 57, MAP_FAILED }, { 3, MAP_FAILED },
|
|
{ 131, MAP_FAILED }, { 1, MAP_FAILED },
|
|
};
|
|
|
|
for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
|
|
HX(mm[m].p = mmap(NULL,
|
|
mm[m].npg * pgs,
|
|
PROT_READ|PROT_WRITE,
|
|
MAP_PRIVATE|MAP_ANON, -1,
|
|
(off_t)0), mm[m].p);
|
|
if (mm[m].p != MAP_FAILED) {
|
|
size_t mo;
|
|
|
|
/* Touch some memory... */
|
|
p = mm[m].p;
|
|
mo = cnt %
|
|
(mm[m].npg * pgs - 1);
|
|
p[mo] = 1;
|
|
cnt += (int)((long)(mm[m].p)
|
|
/ pgs);
|
|
}
|
|
|
|
/* Check cnts and times... */
|
|
mach_time = mach_absolute_time();
|
|
HD(mach_time);
|
|
cnt += (int)mach_time;
|
|
|
|
HX((e = getrusage(RUSAGE_SELF,
|
|
&ru)) == -1, ru);
|
|
if (e != -1) {
|
|
cnt += (int)ru.ru_utime.tv_sec;
|
|
cnt += (int)ru.ru_utime.tv_usec;
|
|
}
|
|
}
|
|
|
|
for (m = 0; m < sizeof mm/sizeof(mm[0]); m++) {
|
|
if (mm[m].p != MAP_FAILED)
|
|
munmap(mm[m].p, mm[m].npg * pgs);
|
|
mm[m].p = MAP_FAILED;
|
|
}
|
|
|
|
HX(stat(".", &st) == -1, st);
|
|
HX(statvfs(".", &stvfs) == -1, stvfs);
|
|
HX(statfs(".", &stfs) == -1, stfs);
|
|
|
|
HX(stat("/", &st) == -1, st);
|
|
HX(statvfs("/", &stvfs) == -1, stvfs);
|
|
HX(statfs("/", &stfs) == -1, stfs);
|
|
|
|
HX((e = fstat(0, &st)) == -1, st);
|
|
if (e == -1) {
|
|
if (S_ISREG(st.st_mode) ||
|
|
S_ISFIFO(st.st_mode) ||
|
|
S_ISSOCK(st.st_mode)) {
|
|
HX(fstatvfs(0, &stvfs) == -1,
|
|
stvfs);
|
|
HX(fstatfs(0, &stfs) == -1,
|
|
stfs);
|
|
HX((off = lseek(0, (off_t)0,
|
|
SEEK_CUR)) < 0, off);
|
|
}
|
|
if (S_ISCHR(st.st_mode)) {
|
|
HX(tcgetattr(0, &tios) == -1,
|
|
tios);
|
|
} else if (S_ISSOCK(st.st_mode)) {
|
|
memset(&ss, 0, sizeof ss);
|
|
ssl = sizeof(ss);
|
|
HX(getpeername(0,
|
|
(void *)&ss, &ssl) == -1,
|
|
ss);
|
|
}
|
|
}
|
|
|
|
HX((e = getrusage(RUSAGE_CHILDREN,
|
|
&ru)) == -1, ru);
|
|
if (e != -1) {
|
|
cnt += (int)ru.ru_utime.tv_sec;
|
|
cnt += (int)ru.ru_utime.tv_usec;
|
|
}
|
|
} else {
|
|
/* Subsequent hashes absorb previous result */
|
|
HD(results);
|
|
}
|
|
|
|
HX((e = gettimeofday(&tv, NULL)) == -1, tv);
|
|
if (e != -1) {
|
|
cnt += (int)tv.tv_sec;
|
|
cnt += (int)tv.tv_usec;
|
|
}
|
|
|
|
HD(cnt);
|
|
}
|
|
|
|
SHA512_Final(results, &ctx);
|
|
memcpy((char *)buf + i, results, MINIMUM(sizeof(results), len - i));
|
|
i += MINIMUM(sizeof(results), len - i);
|
|
}
|
|
explicit_bzero(&ctx, sizeof ctx);
|
|
explicit_bzero(results, sizeof results);
|
|
errno = save_errno;
|
|
return (0); /* satisfied */
|
|
}
|