| /* |
| * Copyright (c) 2001 Damien Miller. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "includes.h" |
| |
| #include <openssl/rand.h> |
| #include <openssl/crypto.h> |
| |
| #include "ssh.h" |
| #include "misc.h" |
| #include "xmalloc.h" |
| #include "atomicio.h" |
| #include "pathnames.h" |
| #include "log.h" |
| |
| /* |
| * Portable OpenSSH PRNG seeding: |
| * If OpenSSL has not "internally seeded" itself (e.g. pulled data from |
| * /dev/random), then we execute a "ssh-rand-helper" program which |
| * collects entropy and writes it to stdout. The child program must |
| * write at least RANDOM_SEED_SIZE bytes. The child is run with stderr |
| * attached, so error/debugging output should be visible. |
| * |
| * XXX: we should tell the child how many bytes we need. |
| */ |
| |
| RCSID("$Id: entropy.c,v 1.50 2005/09/27 09:50:25 dtucker Exp $"); |
| |
| #ifndef OPENSSL_PRNG_ONLY |
| #define RANDOM_SEED_SIZE 48 |
| static uid_t original_uid, original_euid; |
| #endif |
| |
| void |
| seed_rng(void) |
| { |
| #ifndef OPENSSL_PRNG_ONLY |
| int devnull; |
| int p[2]; |
| pid_t pid; |
| int ret; |
| unsigned char buf[RANDOM_SEED_SIZE]; |
| mysig_t old_sigchld; |
| |
| if (RAND_status() == 1) { |
| debug3("RNG is ready, skipping seeding"); |
| return; |
| } |
| |
| debug3("Seeding PRNG from %s", SSH_RAND_HELPER); |
| |
| if ((devnull = open("/dev/null", O_RDWR)) == -1) |
| fatal("Couldn't open /dev/null: %s", strerror(errno)); |
| if (pipe(p) == -1) |
| fatal("pipe: %s", strerror(errno)); |
| |
| old_sigchld = signal(SIGCHLD, SIG_DFL); |
| if ((pid = fork()) == -1) |
| fatal("Couldn't fork: %s", strerror(errno)); |
| if (pid == 0) { |
| dup2(devnull, STDIN_FILENO); |
| dup2(p[1], STDOUT_FILENO); |
| /* Keep stderr open for errors */ |
| close(p[0]); |
| close(p[1]); |
| close(devnull); |
| |
| if (original_uid != original_euid && |
| ( seteuid(getuid()) == -1 || |
| setuid(original_uid) == -1) ) { |
| fprintf(stderr, "(rand child) setuid(%li): %s\n", |
| (long int)original_uid, strerror(errno)); |
| _exit(1); |
| } |
| |
| execl(SSH_RAND_HELPER, "ssh-rand-helper", NULL); |
| fprintf(stderr, "(rand child) Couldn't exec '%s': %s\n", |
| SSH_RAND_HELPER, strerror(errno)); |
| _exit(1); |
| } |
| |
| close(devnull); |
| close(p[1]); |
| |
| memset(buf, '\0', sizeof(buf)); |
| ret = atomicio(read, p[0], buf, sizeof(buf)); |
| if (ret == -1) |
| fatal("Couldn't read from ssh-rand-helper: %s", |
| strerror(errno)); |
| if (ret != sizeof(buf)) |
| fatal("ssh-rand-helper child produced insufficient data"); |
| |
| close(p[0]); |
| |
| if (waitpid(pid, &ret, 0) == -1) |
| fatal("Couldn't wait for ssh-rand-helper completion: %s", |
| strerror(errno)); |
| signal(SIGCHLD, old_sigchld); |
| |
| /* We don't mind if the child exits upon a SIGPIPE */ |
| if (!WIFEXITED(ret) && |
| (!WIFSIGNALED(ret) || WTERMSIG(ret) != SIGPIPE)) |
| fatal("ssh-rand-helper terminated abnormally"); |
| if (WEXITSTATUS(ret) != 0) |
| fatal("ssh-rand-helper exit with exit status %d", ret); |
| |
| RAND_add(buf, sizeof(buf), sizeof(buf)); |
| memset(buf, '\0', sizeof(buf)); |
| |
| #endif /* OPENSSL_PRNG_ONLY */ |
| if (RAND_status() != 1) |
| fatal("PRNG is not seeded"); |
| } |
| |
| void |
| init_rng(void) |
| { |
| /* |
| * OpenSSL version numbers: MNNFFPPS: major minor fix patch status |
| * We match major, minor, fix and status (not patch) |
| */ |
| if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L) |
| fatal("OpenSSL version mismatch. Built against %lx, you " |
| "have %lx", OPENSSL_VERSION_NUMBER, SSLeay()); |
| |
| #ifndef OPENSSL_PRNG_ONLY |
| original_uid = getuid(); |
| original_euid = geteuid(); |
| #endif |
| } |
| |