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 #ifdef HAVE_SYS_STAT_H
31 # include <sys/stat.h>
40 #include <openssl/rand.h>
41 #include <openssl/crypto.h>
42 #include <openssl/err.h>
48 #include "pathnames.h"
53 * Portable OpenSSH PRNG seeding:
54 * If OpenSSL has not "internally seeded" itself (e.g. pulled data from
55 * /dev/random), then we execute a "ssh-rand-helper" program which
56 * collects entropy and writes it to stdout. The child program must
57 * write at least RANDOM_SEED_SIZE bytes. The child is run with stderr
58 * attached, so error/debugging output should be visible.
60 * XXX: we should tell the child how many bytes we need.
63 #ifndef OPENSSL_PRNG_ONLY
64 #define RANDOM_SEED_SIZE 48
65 static uid_t original_uid, original_euid;
71 #ifndef OPENSSL_PRNG_ONLY
76 unsigned char buf[RANDOM_SEED_SIZE];
79 if (RAND_status() == 1) {
80 debug3("RNG is ready, skipping seeding");
84 debug3("Seeding PRNG from %s", SSH_RAND_HELPER);
86 if ((devnull = open("/dev/null", O_RDWR)) == -1)
87 fatal("Couldn't open /dev/null: %s", strerror(errno));
89 fatal("pipe: %s", strerror(errno));
91 old_sigchld = signal(SIGCHLD, SIG_DFL);
92 if ((pid = fork()) == -1)
93 fatal("Couldn't fork: %s", strerror(errno));
95 dup2(devnull, STDIN_FILENO);
96 dup2(p[1], STDOUT_FILENO);
97 /* Keep stderr open for errors */
102 if (original_uid != original_euid &&
103 ( seteuid(getuid()) == -1 ||
104 setuid(original_uid) == -1) ) {
105 fprintf(stderr, "(rand child) setuid(%li): %s\n",
106 (long int)original_uid, strerror(errno));
110 execl(SSH_RAND_HELPER, "ssh-rand-helper", NULL);
111 fprintf(stderr, "(rand child) Couldn't exec '%s': %s\n",
112 SSH_RAND_HELPER, strerror(errno));
119 memset(buf, '\0', sizeof(buf));
120 ret = atomicio(read, p[0], buf, sizeof(buf));
122 fatal("Couldn't read from ssh-rand-helper: %s",
124 if (ret != sizeof(buf))
125 fatal("ssh-rand-helper child produced insufficient data");
129 if (waitpid(pid, &ret, 0) == -1)
130 fatal("Couldn't wait for ssh-rand-helper completion: %s",
132 signal(SIGCHLD, old_sigchld);
134 /* We don't mind if the child exits upon a SIGPIPE */
135 if (!WIFEXITED(ret) &&
136 (!WIFSIGNALED(ret) || WTERMSIG(ret) != SIGPIPE))
137 fatal("ssh-rand-helper terminated abnormally");
138 if (WEXITSTATUS(ret) != 0)
139 fatal("ssh-rand-helper exit with exit status %d", ret);
141 RAND_add(buf, sizeof(buf), sizeof(buf));
142 memset(buf, '\0', sizeof(buf));
144 #endif /* OPENSSL_PRNG_ONLY */
145 if (RAND_status() != 1)
146 fatal("PRNG is not seeded");
153 * OpenSSL version numbers: MNNFFPPS: major minor fix patch status
154 * We match major, minor, fix and status (not patch)
156 if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L)
157 fatal("OpenSSL version mismatch. Built against %lx, you "
158 "have %lx", OPENSSL_VERSION_NUMBER, SSLeay());
160 #ifndef OPENSSL_PRNG_ONLY
161 original_uid = getuid();
162 original_euid = geteuid();
166 #ifndef OPENSSL_PRNG_ONLY
168 rexec_send_rng_seed(Buffer *m)
170 u_char buf[RANDOM_SEED_SIZE];
172 if (RAND_bytes(buf, sizeof(buf)) <= 0) {
173 error("Couldn't obtain random bytes (error %ld)",
175 buffer_put_string(m, "", 0);
177 buffer_put_string(m, buf, sizeof(buf));
181 rexec_recv_rng_seed(Buffer *m)
186 buf = buffer_get_string_ret(m, &len);
188 debug3("rexec_recv_rng_seed: seeding rng with %u bytes", len);
189 RAND_add(buf, len, len);