blob: e5b45b0b614f3b8119fe06f7f6ad8e6fa7ca9190 [file] [log] [blame]
Damien Miller040f3832000-04-03 14:50:43 +10001/*
Damien Miller62116dc2001-12-24 01:41:47 +11002 * Copyright (c) 2001 Damien Miller. All rights reserved.
Damien Miller040f3832000-04-03 14:50:43 +10003 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
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.
Damien Miller040f3832000-04-03 14:50:43 +100012 *
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.
23 */
24
25#include "includes.h"
26
Damien Miller5f056372000-04-16 12:31:48 +100027#include <openssl/rand.h>
Damien Miller767c7fc2001-02-27 09:20:57 +110028#include <openssl/crypto.h>
Darren Tuckerc6f82192005-09-27 22:46:32 +100029#include <openssl/err.h>
Damien Miller040f3832000-04-03 14:50:43 +100030
Ben Lindstrom226cfa02001-01-22 05:34:40 +000031#include "ssh.h"
Damien Millera1072a82001-02-18 15:28:11 +110032#include "misc.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000033#include "xmalloc.h"
34#include "atomicio.h"
Ben Lindstromcb577332001-01-22 21:06:19 +000035#include "pathnames.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000036#include "log.h"
Darren Tuckerc6f82192005-09-27 22:46:32 +100037#include "buffer.h"
38#include "bufaux.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000039
Damien Miller14c12cb2000-06-07 22:20:23 +100040/*
Damien Miller62116dc2001-12-24 01:41:47 +110041 * Portable OpenSSH PRNG seeding:
Damien Millera8e06ce2003-11-21 23:48:55 +110042 * If OpenSSL has not "internally seeded" itself (e.g. pulled data from
43 * /dev/random), then we execute a "ssh-rand-helper" program which
44 * collects entropy and writes it to stdout. The child program must
Damien Miller62116dc2001-12-24 01:41:47 +110045 * write at least RANDOM_SEED_SIZE bytes. The child is run with stderr
46 * attached, so error/debugging output should be visible.
47 *
48 * XXX: we should tell the child how many bytes we need.
Damien Miller14c12cb2000-06-07 22:20:23 +100049 */
Damien Miller62116dc2001-12-24 01:41:47 +110050
Darren Tucker46e7ba52005-09-28 08:26:30 +100051RCSID("$Id: entropy.c,v 1.52 2005/09/27 22:26:30 dtucker Exp $");
Damien Miller6c21c512002-01-22 21:57:53 +110052
53#ifndef OPENSSL_PRNG_ONLY
Damien Miller62116dc2001-12-24 01:41:47 +110054#define RANDOM_SEED_SIZE 48
Damien Miller62116dc2001-12-24 01:41:47 +110055static uid_t original_uid, original_euid;
Damien Miller6c21c512002-01-22 21:57:53 +110056#endif
Damien Miller62116dc2001-12-24 01:41:47 +110057
Damien Miller14c12cb2000-06-07 22:20:23 +100058void
59seed_rng(void)
60{
Damien Miller6c21c512002-01-22 21:57:53 +110061#ifndef OPENSSL_PRNG_ONLY
Damien Miller62116dc2001-12-24 01:41:47 +110062 int devnull;
63 int p[2];
64 pid_t pid;
65 int ret;
66 unsigned char buf[RANDOM_SEED_SIZE];
Damien Millera370f4d2002-04-18 22:53:22 +100067 mysig_t old_sigchld;
Kevin Stevesef4eea92001-02-05 12:42:17 +000068
Damien Miller62116dc2001-12-24 01:41:47 +110069 if (RAND_status() == 1) {
70 debug3("RNG is ready, skipping seeding");
71 return;
Damien Miller08006472000-06-26 13:55:31 +100072 }
Kevin Stevesef4eea92001-02-05 12:42:17 +000073
Kevin Steves58193072002-03-11 00:16:34 +000074 debug3("Seeding PRNG from %s", SSH_RAND_HELPER);
Damien Miller62116dc2001-12-24 01:41:47 +110075
76 if ((devnull = open("/dev/null", O_RDWR)) == -1)
77 fatal("Couldn't open /dev/null: %s", strerror(errno));
78 if (pipe(p) == -1)
79 fatal("pipe: %s", strerror(errno));
80
Ben Lindstrom5ade9ab2003-08-25 01:16:21 +000081 old_sigchld = signal(SIGCHLD, SIG_DFL);
Damien Miller62116dc2001-12-24 01:41:47 +110082 if ((pid = fork()) == -1)
83 fatal("Couldn't fork: %s", strerror(errno));
84 if (pid == 0) {
85 dup2(devnull, STDIN_FILENO);
86 dup2(p[1], STDOUT_FILENO);
87 /* Keep stderr open for errors */
88 close(p[0]);
89 close(p[1]);
90 close(devnull);
91
Damien Millera8e06ce2003-11-21 23:48:55 +110092 if (original_uid != original_euid &&
93 ( seteuid(getuid()) == -1 ||
Tim Ricef02dccc2002-04-21 11:26:10 -070094 setuid(original_uid) == -1) ) {
Damien Millera8e06ce2003-11-21 23:48:55 +110095 fprintf(stderr, "(rand child) setuid(%li): %s\n",
Damien Millerc46b6bc2003-05-16 15:51:44 +100096 (long int)original_uid, strerror(errno));
Damien Miller62116dc2001-12-24 01:41:47 +110097 _exit(1);
98 }
Damien Miller787b2ec2003-11-21 23:56:47 +110099
Damien Miller62116dc2001-12-24 01:41:47 +1100100 execl(SSH_RAND_HELPER, "ssh-rand-helper", NULL);
Damien Millera8e06ce2003-11-21 23:48:55 +1100101 fprintf(stderr, "(rand child) Couldn't exec '%s': %s\n",
Damien Miller62116dc2001-12-24 01:41:47 +1100102 SSH_RAND_HELPER, strerror(errno));
103 _exit(1);
104 }
105
106 close(devnull);
107 close(p[1]);
108
109 memset(buf, '\0', sizeof(buf));
110 ret = atomicio(read, p[0], buf, sizeof(buf));
111 if (ret == -1)
112 fatal("Couldn't read from ssh-rand-helper: %s",
113 strerror(errno));
114 if (ret != sizeof(buf))
115 fatal("ssh-rand-helper child produced insufficient data");
116
117 close(p[0]);
118
119 if (waitpid(pid, &ret, 0) == -1)
Damien Millerb6f72f52005-07-17 17:26:43 +1000120 fatal("Couldn't wait for ssh-rand-helper completion: %s",
121 strerror(errno));
Ben Lindstrom5ade9ab2003-08-25 01:16:21 +0000122 signal(SIGCHLD, old_sigchld);
Damien Miller62116dc2001-12-24 01:41:47 +1100123
124 /* We don't mind if the child exits upon a SIGPIPE */
Damien Millera8e06ce2003-11-21 23:48:55 +1100125 if (!WIFEXITED(ret) &&
Damien Miller62116dc2001-12-24 01:41:47 +1100126 (!WIFSIGNALED(ret) || WTERMSIG(ret) != SIGPIPE))
127 fatal("ssh-rand-helper terminated abnormally");
128 if (WEXITSTATUS(ret) != 0)
129 fatal("ssh-rand-helper exit with exit status %d", ret);
130
131 RAND_add(buf, sizeof(buf), sizeof(buf));
Damien Miller14c12cb2000-06-07 22:20:23 +1000132 memset(buf, '\0', sizeof(buf));
Damien Miller6c21c512002-01-22 21:57:53 +1100133
134#endif /* OPENSSL_PRNG_ONLY */
135 if (RAND_status() != 1)
136 fatal("PRNG is not seeded");
Damien Miller14c12cb2000-06-07 22:20:23 +1000137}
138
Damien Miller60bc5172001-03-19 09:38:15 +1100139void
Damien Millera8e06ce2003-11-21 23:48:55 +1100140init_rng(void)
Damien Miller767c7fc2001-02-27 09:20:57 +1100141{
Damien Millerbb7c9762001-02-26 20:49:58 +1100142 /*
Damien Miller62116dc2001-12-24 01:41:47 +1100143 * OpenSSL version numbers: MNNFFPPS: major minor fix patch status
144 * We match major, minor, fix and status (not patch)
Damien Millerbb7c9762001-02-26 20:49:58 +1100145 */
Damien Miller62116dc2001-12-24 01:41:47 +1100146 if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L)
147 fatal("OpenSSL version mismatch. Built against %lx, you "
148 "have %lx", OPENSSL_VERSION_NUMBER, SSLeay());
Kevin Stevesef4eea92001-02-05 12:42:17 +0000149
Damien Miller6c21c512002-01-22 21:57:53 +1100150#ifndef OPENSSL_PRNG_ONLY
Darren Tuckerf1377bd2005-09-27 19:50:25 +1000151 original_uid = getuid();
152 original_euid = geteuid();
Damien Miller6c21c512002-01-22 21:57:53 +1100153#endif
Damien Millerf9b625c2000-07-09 22:42:32 +1000154}
Damien Miller6c21c512002-01-22 21:57:53 +1100155
Darren Tuckerc6f82192005-09-27 22:46:32 +1000156#ifndef OPENSSL_PRNG_ONLY
157void
158rexec_send_rng_seed(Buffer *m)
159{
160 u_char buf[RANDOM_SEED_SIZE];
161
162 if (RAND_bytes(buf, sizeof(buf)) <= 0) {
163 error("Couldn't obtain random bytes (error %ld)",
164 ERR_get_error());
165 buffer_put_string(m, "", 0);
166 } else
167 buffer_put_string(m, buf, sizeof(buf));
168}
169
170void
171rexec_recv_rng_seed(Buffer *m)
172{
Darren Tucker46e7ba52005-09-28 08:26:30 +1000173 u_char *buf;
Darren Tuckerc6f82192005-09-27 22:46:32 +1000174 u_int len;
175
176 buf = buffer_get_string_ret(m, &len);
177 if (buf != NULL) {
178 debug3("rexec_recv_rng_seed: seeding rng with %u bytes", len);
179 RAND_add(buf, len, len);
180 }
181}
182#endif