kc3-lang/libbsd/src/getentropy_osx.c

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• Hash : 847e682f
  Author :
  Date : 2021-02-07T00:09:30
  

  Use libmd hashing function implementations instead of embedding our own This splits the implementation responsibilities, and reduces embedded code copies, which was one of the driving points with this project to start with, so it's nice to give a good example.

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• src/getentropy_osx.c

• /*	$OpenBSD: getentropy_osx.c,v 1.11 2016/09/03 15:24:09 bcook 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 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, (uint8_t *)(x), (l)))
  #define HD(x)	 (SHA512_Update(&ctx, (uint8_t *)&(x), sizeof (x)))
  #define HF(x)    (SHA512_Update(&ctx, (uint8_t *)&(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);
  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);
  }
  
  /*
   * 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)
  {
  	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);
  	if (gotdata(buf, len) == 0) {
  		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
  	uint64_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, 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);
  }
  

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