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 <sys/types.h>
30 #include <openssl/rand.h>
31 #include <openssl/crypto.h>
32 #include <openssl/err.h>
38 #include "pathnames.h"
44 * Portable OpenSSH PRNG seeding:
45 * If OpenSSL has not "internally seeded" itself (e.g. pulled data from
46 * /dev/random), then we execute a "ssh-rand-helper" program which
47 * collects entropy and writes it to stdout. The child program must
48 * write at least RANDOM_SEED_SIZE bytes. The child is run with stderr
49 * attached, so error/debugging output should be visible.
51 * XXX: we should tell the child how many bytes we need.
56 #ifndef OPENSSL_PRNG_ONLY
57 #define RANDOM_SEED_SIZE 48
58 static uid_t original_uid, original_euid;
64 #ifndef OPENSSL_PRNG_ONLY
69 unsigned char buf[RANDOM_SEED_SIZE];
72 if (RAND_status() == 1) {
73 debug3("RNG is ready, skipping seeding");
77 debug3("Seeding PRNG from %s", SSH_RAND_HELPER);
79 if ((devnull = open("/dev/null", O_RDWR)) == -1)
80 fatal("Couldn't open /dev/null: %s", strerror(errno));
82 fatal("pipe: %s", strerror(errno));
84 old_sigchld = signal(SIGCHLD, SIG_DFL);
85 if ((pid = fork()) == -1)
86 fatal("Couldn't fork: %s", strerror(errno));
88 dup2(devnull, STDIN_FILENO);
89 dup2(p[1], STDOUT_FILENO);
90 /* Keep stderr open for errors */
95 if (original_uid != original_euid &&
96 ( seteuid(getuid()) == -1 ||
97 setuid(original_uid) == -1) ) {
98 fprintf(stderr, "(rand child) setuid(%li): %s\n",
99 (long int)original_uid, strerror(errno));
103 execl(SSH_RAND_HELPER, "ssh-rand-helper", NULL);
104 fprintf(stderr, "(rand child) Couldn't exec '%s': %s\n",
105 SSH_RAND_HELPER, strerror(errno));
112 memset(buf, '\0', sizeof(buf));
113 ret = atomicio(read, p[0], buf, sizeof(buf));
115 fatal("Couldn't read from ssh-rand-helper: %s",
117 if (ret != sizeof(buf))
118 fatal("ssh-rand-helper child produced insufficient data");
122 if (waitpid(pid, &ret, 0) == -1)
123 fatal("Couldn't wait for ssh-rand-helper completion: %s",
125 signal(SIGCHLD, old_sigchld);
127 /* We don't mind if the child exits upon a SIGPIPE */
128 if (!WIFEXITED(ret) &&
129 (!WIFSIGNALED(ret) || WTERMSIG(ret) != SIGPIPE))
130 fatal("ssh-rand-helper terminated abnormally");
131 if (WEXITSTATUS(ret) != 0)
132 fatal("ssh-rand-helper exit with exit status %d", ret);
134 RAND_add(buf, sizeof(buf), sizeof(buf));
135 memset(buf, '\0', sizeof(buf));
137 #endif /* OPENSSL_PRNG_ONLY */
138 if (RAND_status() != 1)
139 fatal("PRNG is not seeded");
146 * OpenSSL version numbers: MNNFFPPS: major minor fix patch status
147 * We match major, minor, fix and status (not patch)
149 if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L)
150 fatal("OpenSSL version mismatch. Built against %lx, you "
151 "have %lx", OPENSSL_VERSION_NUMBER, SSLeay());
153 #ifndef OPENSSL_PRNG_ONLY
154 original_uid = getuid();
155 original_euid = geteuid();
159 #ifndef OPENSSL_PRNG_ONLY
161 rexec_send_rng_seed(Buffer *m)
163 u_char buf[RANDOM_SEED_SIZE];
165 if (RAND_bytes(buf, sizeof(buf)) <= 0) {
166 error("Couldn't obtain random bytes (error %ld)",
168 buffer_put_string(m, "", 0);
170 buffer_put_string(m, buf, sizeof(buf));
174 rexec_recv_rng_seed(Buffer *m)
179 buf = buffer_get_string_ret(m, &len);
181 debug3("rexec_recv_rng_seed: seeding rng with %u bytes", len);
182 RAND_add(buf, len, len);