/* $OpenBSD: getentropy_solaris.c,v 1.3 2014/07/12 14:46:31 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.
*/
#include "config.h"
#include <sys/types.h>
#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/resource.h>
#include <sys/syscall.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>
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#include <stdio.h>
#include <termios.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>
#ifdef HAVE_SYS_SHA2_H
#include <sys/sha2.h>
#define SHA512_Init SHA512Init
#define SHA512_Update SHA512Update
#define SHA512_Final SHA512Final
#else
#include "openssl/sha.h"
#endif
#include <sys/vfs.h>
#include <sys/statfs.h>
#include <sys/loadavg.h>
#define REPEAT 5
#define min(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);
#ifdef CAN_REFERENCE_MAIN
extern int main(int, char *argv[]);
#endif
static int gotdata(char *buf, size_t len);
static int getentropy_urandom(void *buf, size_t len, const char *path,
int devfscheck);
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
*
* Solaris provides /dev/urandom as a symbolic link to
* /devices/pseudo/random@0:urandom which is provided by
* a devfs filesystem. Best practice is to use O_NOFOLLOW,
* so we must try the unpublished name directly.
*
* This can fail if the process is inside a chroot which lacks
* the devfs mount, or if file descriptors are exhausted.
*/
ret = getentropy_urandom(buf, len,
"/devices/pseudo/random@0:urandom", 1);
if (ret != -1)
return (ret);
/*
* Unfortunately, chroot spaces on Solaris are sometimes setup
* with direct device node of the well-known /dev/urandom name
* (perhaps to avoid dragging all of devfs into the space).
*
* This can fail if the process is inside a chroot or if file
* descriptors are exhausted.
*/
ret = getentropy_urandom(buf, len, "/dev/urandom", 0);
if (ret != -1)
return (ret);
/*
* Entropy collection via /dev/urandom has failed.
*
* No other API exists for collecting entropy, and we have
* no failsafe way to get it on Solaris 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 Solaris
* does not provide a failsafe API for entropy collection.
*
* We hope this demonstrates that Solaris 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);
}
/*
* Basic sanity checking; wish we could do better.
*/
static int
gotdata(char *buf, size_t len)
{
char any_set = 0;
size_t i;
for (i = 0; i < len; ++i)
any_set |= buf[i];
if (any_set == 0)
return -1;
return 0;
}
static int
getentropy_urandom(void *buf, size_t len, const char *path, int devfscheck)
{
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(path, 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) ||
(devfscheck && (strcmp(st.st_fstype, "devfs") != 0))) {
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);
if (gotdata(buf, len) == 0) {
errno = save_errno;
return 0; /* satisfied */
}
nodevrandom:
errno = EIO;
return -1;
}
static const int cl[] = {
CLOCK_REALTIME,
#ifdef CLOCK_MONOTONIC
CLOCK_MONOTONIC,
#endif
#ifdef CLOCK_MONOTONIC_RAW
CLOCK_MONOTONIC_RAW,
#endif
#ifdef CLOCK_TAI
CLOCK_TAI,
#endif
#ifdef CLOCK_VIRTUAL
CLOCK_VIRTUAL,
#endif
#ifdef CLOCK_UPTIME
CLOCK_UPTIME,
#endif
#ifdef CLOCK_PROCESS_CPUTIME_ID
CLOCK_PROCESS_CPUTIME_ID,
#endif
#ifdef CLOCK_THREAD_CPUTIME_ID
CLOCK_THREAD_CPUTIME_ID,
#endif
};
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;
double loadavg[3];
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;
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;
}
for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]); ii++)
HX(clock_gettime(cl[ii], &ts) == -1, ts);
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);
HX((getloadavg(loadavg, 3) == -1), loadavg);
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);
#ifdef CAN_REFERENCE_MAIN
HF(main); /* an addr in program */
#endif
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;
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... */
for (ii = 0; ii < sizeof(cl)/sizeof(cl[0]);
ii++) {
HX((e = clock_gettime(cl[ii],
&ts)) == -1, ts);
if (e != -1)
cnt += (int)ts.tv_nsec;
}
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(stat("/", &st) == -1, st);
HX(statvfs("/", &stvfs) == -1, stvfs);
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((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, min(sizeof(results), len - i));
i += min(sizeof(results), len - i);
}
memset(results, 0, sizeof results);
if (gotdata(buf, len) == 0) {
errno = save_errno;
return 0; /* satisfied */
}
errno = EIO;
return -1;
}
