2 * Copyright (c) 2001 Damien Miller. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 #include <openssl/rand.h>
28 #include <openssl/crypto.h>
34 #include "pathnames.h"
38 * Portable OpenSSH PRNG seeding:
39 * If OpenSSL has not "internally seeded" itself (e.g. pulled data from
40 * /dev/random), then we execute a "ssh-rand-helper" program which
41 * collects entropy and writes it to stdout. The child program must
42 * write at least RANDOM_SEED_SIZE bytes. The child is run with stderr
43 * attached, so error/debugging output should be visible.
45 * XXX: we should tell the child how many bytes we need.
50 #ifndef OPENSSL_PRNG_ONLY
51 #define RANDOM_SEED_SIZE 48
52 static uid_t original_uid, original_euid;
58 #ifndef OPENSSL_PRNG_ONLY
63 unsigned char buf[RANDOM_SEED_SIZE];
65 if (RAND_status() == 1) {
66 debug3("RNG is ready, skipping seeding");
70 debug3("Seeding PRNG from %s", SSH_RAND_HELPER);
72 if ((devnull = open("/dev/null", O_RDWR)) == -1)
73 fatal("Couldn't open /dev/null: %s", strerror(errno));
75 fatal("pipe: %s", strerror(errno));
77 if ((pid = fork()) == -1)
78 fatal("Couldn't fork: %s", strerror(errno));
80 dup2(devnull, STDIN_FILENO);
81 dup2(p[1], STDOUT_FILENO);
82 /* Keep stderr open for errors */
87 if (original_uid != original_euid &&
88 setuid(original_uid) == -1) {
89 fprintf(stderr, "(rand child) setuid: %s\n",
94 execl(SSH_RAND_HELPER, "ssh-rand-helper", NULL);
95 fprintf(stderr, "(rand child) Couldn't exec '%s': %s\n",
96 SSH_RAND_HELPER, strerror(errno));
103 memset(buf, '\0', sizeof(buf));
104 ret = atomicio(read, p[0], buf, sizeof(buf));
106 fatal("Couldn't read from ssh-rand-helper: %s",
108 if (ret != sizeof(buf))
109 fatal("ssh-rand-helper child produced insufficient data");
113 if (waitpid(pid, &ret, 0) == -1)
114 fatal("Couldn't wait for ssh-rand-helper completion: %s",
117 /* We don't mind if the child exits upon a SIGPIPE */
118 if (!WIFEXITED(ret) &&
119 (!WIFSIGNALED(ret) || WTERMSIG(ret) != SIGPIPE))
120 fatal("ssh-rand-helper terminated abnormally");
121 if (WEXITSTATUS(ret) != 0)
122 fatal("ssh-rand-helper exit with exit status %d", ret);
124 RAND_add(buf, sizeof(buf), sizeof(buf));
125 memset(buf, '\0', sizeof(buf));
127 #endif /* OPENSSL_PRNG_ONLY */
128 if (RAND_status() != 1)
129 fatal("PRNG is not seeded");
136 * OpenSSL version numbers: MNNFFPPS: major minor fix patch status
137 * We match major, minor, fix and status (not patch)
139 if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L)
140 fatal("OpenSSL version mismatch. Built against %lx, you "
141 "have %lx", OPENSSL_VERSION_NUMBER, SSLeay());
143 #ifndef OPENSSL_PRNG_ONLY
144 if ((original_uid = getuid()) == -1)
145 fatal("getuid: %s", strerror(errno));
146 if ((original_euid = geteuid()) == -1)
147 fatal("geteuid: %s", strerror(errno));