add initial AIX getentropy/arc4random files. Thanks to Michael Felt.

src/lib/libcrypto/arc4random/arc4random_aix.h

@@ -0,0 +1,80 @@
+/*	$OpenBSD: arc4random_aix.h,v 1.1 2015/03/30 11:29:48 bcook Exp $	*/
+
+/*
+ * Copyright (c) 1996, David Mazieres <dm@uun.org>
+ * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
+ * Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
+ * Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org>
+ *
+ * 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.
+ */
+
+/*
+ * Stub functions for portability.
+ */
+
+#include <sys/mman.h>
+
+#include <pthread.h>
+#include <signal.h>
+
+static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
+#define _ARC4_LOCK()   pthread_mutex_lock(&arc4random_mtx)
+#define _ARC4_UNLOCK() pthread_mutex_unlock(&arc4random_mtx)
+
+#define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
+
+static inline void
+_getentropy_fail(void)
+{
+	raise(SIGKILL);
+}
+
+static volatile sig_atomic_t _rs_forked;
+
+static inline void
+_rs_forkhandler(void)
+{
+	_rs_forked = 1;
+}
+
+static inline void
+_rs_forkdetect(void)
+{
+	static pid_t _rs_pid = 0;
+	pid_t pid = getpid();
+
+	if (_rs_pid == 0 || _rs_pid != pid || _rs_forked) {
+		_rs_pid = pid;
+		_rs_forked = 0;
+		if (rs)
+			memset(rs, 0, sizeof(*rs));
+	}
+}
+
+static inline int
+_rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
+{
+	if ((*rsp = mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,
+	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
+		return (-1);
+
+	if ((*rsxp = mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,
+	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
+		munmap(*rsp, sizeof(**rsp));
+		return (-1);
+	}
+
+	_ARC4_ATFORK(_rs_forkhandler);
+	return (0);
+}

src/lib/libcrypto/arc4random/getentropy_aix.c

@@ -0,0 +1,421 @@
+/*	$OpenBSD: getentropy_aix.c,v 1.1 2015/03/30 11:29:48 bcook Exp $	*/
+
+/*
+ * Copyright (c) 2015 Michael Felt <aixtools@gmail.com>
+ * 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.
+ *
+ * Intended to Emulate getentropy(2) as documented at:
+ * http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man2/getentropy.2
+ */
+/*
+ * -lperfstat is needed for the psuedo entropy data
+ */
+
+#include <sys/mman.h>
+#include <sys/procfs.h>
+#include <sys/protosw.h>
+#include <sys/resource.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/statvfs.h>
+#include <sys/timers.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <termios.h>
+
+#include <openssl/sha.h>
+
+#include <libperfstat.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);
+
+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
+	 */
+	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 AIX 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 AIX
+	 * does not provide a failsafe API for entropy collection.
+	 *
+	 * We hope this demonstrates that AIX 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)) {
+		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 = sysconf(_SC_PAGESIZE), faster = 0, repeat;
+	static int cnt;
+	struct timespec ts;
+	struct timeval tv;
+	perfstat_cpu_total_t cpustats;
+	perfstat_cpu_total_wpar_t cpustats_wpar;
+	perfstat_partition_total_t lparstats;
+	perfstat_disk_total_t diskinfo;
+	perfstat_netinterface_total_t netinfo;
+	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;
+			}
+
+			HX(perfstat_cpu_total(NULL, &cpustats,
+			    sizeof(cpustats), 1) == -1, cpustats);
+
+			HX(perfstat_cpu_total_wpar(NULL, &cpustats_wpar,
+			    sizeof(cpustats_wpar), 1) == -1, cpustats_wpar);
+
+			HX(perfstat_partition_total(NULL, &lparstats,
+			    sizeof(lparstats), 1) == -1, lparstats);
+
+			HX(perfstat_disk_total(NULL, &diskinfo,
+			    sizeof(diskinfo), 1) == -1, diskinfo);
+
+			HX(perfstat_netinterface_total(NULL, &netinfo,
+			    sizeof(netinfo), 1) == -1, netinfo);
+
+			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);
+
+			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;
+				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);
+	}
+	explicit_bzero(&ctx, sizeof ctx);
+	explicit_bzero(results, sizeof results);
+	if (gotdata(buf, len) == 0) {
+		errno = save_errno;
+		return 0;		/* satisfied */
+	}
+	errno = EIO;
+	return -1;
+}

src/lib/libcrypto/crypto/arc4random_aix.h

@@ -0,0 +1,80 @@
+/*	$OpenBSD: arc4random_aix.h,v 1.1 2015/03/30 11:29:48 bcook Exp $	*/
+
+/*
+ * Copyright (c) 1996, David Mazieres <dm@uun.org>
+ * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
+ * Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
+ * Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org>
+ *
+ * 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.
+ */
+
+/*
+ * Stub functions for portability.
+ */
+
+#include <sys/mman.h>
+
+#include <pthread.h>
+#include <signal.h>
+
+static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
+#define _ARC4_LOCK()   pthread_mutex_lock(&arc4random_mtx)
+#define _ARC4_UNLOCK() pthread_mutex_unlock(&arc4random_mtx)
+
+#define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
+
+static inline void
+_getentropy_fail(void)
+{
+	raise(SIGKILL);
+}
+
+static volatile sig_atomic_t _rs_forked;
+
+static inline void
+_rs_forkhandler(void)
+{
+	_rs_forked = 1;
+}
+
+static inline void
+_rs_forkdetect(void)
+{
+	static pid_t _rs_pid = 0;
+	pid_t pid = getpid();
+
+	if (_rs_pid == 0 || _rs_pid != pid || _rs_forked) {
+		_rs_pid = pid;
+		_rs_forked = 0;
+		if (rs)
+			memset(rs, 0, sizeof(*rs));
+	}
+}
+
+static inline int
+_rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
+{
+	if ((*rsp = mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,
+	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
+		return (-1);
+
+	if ((*rsxp = mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,
+	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
+		munmap(*rsp, sizeof(**rsp));
+		return (-1);
+	}
+
+	_ARC4_ATFORK(_rs_forkhandler);
+	return (0);
+}

src/lib/libcrypto/crypto/getentropy_aix.c

@@ -0,0 +1,421 @@
+/*	$OpenBSD: getentropy_aix.c,v 1.1 2015/03/30 11:29:48 bcook Exp $	*/
+
+/*
+ * Copyright (c) 2015 Michael Felt <aixtools@gmail.com>
+ * 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.
+ *
+ * Intended to Emulate getentropy(2) as documented at:
+ * http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man2/getentropy.2
+ */
+/*
+ * -lperfstat is needed for the psuedo entropy data
+ */
+
+#include <sys/mman.h>
+#include <sys/procfs.h>
+#include <sys/protosw.h>
+#include <sys/resource.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/statvfs.h>
+#include <sys/timers.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <termios.h>
+
+#include <openssl/sha.h>
+
+#include <libperfstat.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);
+
+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
+	 */
+	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 AIX 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 AIX
+	 * does not provide a failsafe API for entropy collection.
+	 *
+	 * We hope this demonstrates that AIX 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)) {
+		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 = sysconf(_SC_PAGESIZE), faster = 0, repeat;
+	static int cnt;
+	struct timespec ts;
+	struct timeval tv;
+	perfstat_cpu_total_t cpustats;
+	perfstat_cpu_total_wpar_t cpustats_wpar;
+	perfstat_partition_total_t lparstats;
+	perfstat_disk_total_t diskinfo;
+	perfstat_netinterface_total_t netinfo;
+	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;
+			}
+
+			HX(perfstat_cpu_total(NULL, &cpustats,
+			    sizeof(cpustats), 1) == -1, cpustats);
+
+			HX(perfstat_cpu_total_wpar(NULL, &cpustats_wpar,
+			    sizeof(cpustats_wpar), 1) == -1, cpustats_wpar);
+
+			HX(perfstat_partition_total(NULL, &lparstats,
+			    sizeof(lparstats), 1) == -1, lparstats);
+
+			HX(perfstat_disk_total(NULL, &diskinfo,
+			    sizeof(diskinfo), 1) == -1, diskinfo);
+
+			HX(perfstat_netinterface_total(NULL, &netinfo,
+			    sizeof(netinfo), 1) == -1, netinfo);
+
+			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);
+
+			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;
+				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);
+	}
+	explicit_bzero(&ctx, sizeof ctx);
+	explicit_bzero(results, sizeof results);
+	if (gotdata(buf, len) == 0) {
+		errno = save_errno;
+		return 0;		/* satisfied */
+	}
+	errno = EIO;
+	return -1;
+}