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Diffstat (limited to 'crypto/openssh/entropy.c')
-rw-r--r-- | crypto/openssh/entropy.c | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/crypto/openssh/entropy.c b/crypto/openssh/entropy.c new file mode 100644 index 0000000..dcc8689 --- /dev/null +++ b/crypto/openssh/entropy.c @@ -0,0 +1,154 @@ +/* + * 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 1.44 2002/06/09 19:41:48 mouring 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 = mysignal(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(%d): %s\n", + 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)); + mysignal(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 + if ((original_uid = getuid()) == -1) + fatal("getuid: %s", strerror(errno)); + if ((original_euid = geteuid()) == -1) + fatal("geteuid: %s", strerror(errno)); +#endif +} + |