1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate * Copyright (c) 2001 Damien Miller. All rights reserved.
3*0Sstevel@tonic-gate *
4*0Sstevel@tonic-gate * Redistribution and use in source and binary forms, with or without
5*0Sstevel@tonic-gate * modification, are permitted provided that the following conditions
6*0Sstevel@tonic-gate * are met:
7*0Sstevel@tonic-gate * 1. Redistributions of source code must retain the above copyright
8*0Sstevel@tonic-gate * notice, this list of conditions and the following disclaimer.
9*0Sstevel@tonic-gate * 2. Redistributions in binary form must reproduce the above copyright
10*0Sstevel@tonic-gate * notice, this list of conditions and the following disclaimer in the
11*0Sstevel@tonic-gate * documentation and/or other materials provided with the distribution.
12*0Sstevel@tonic-gate *
13*0Sstevel@tonic-gate * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14*0Sstevel@tonic-gate * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15*0Sstevel@tonic-gate * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16*0Sstevel@tonic-gate * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17*0Sstevel@tonic-gate * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18*0Sstevel@tonic-gate * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19*0Sstevel@tonic-gate * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20*0Sstevel@tonic-gate * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21*0Sstevel@tonic-gate * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22*0Sstevel@tonic-gate * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23*0Sstevel@tonic-gate */
24*0Sstevel@tonic-gate
25*0Sstevel@tonic-gate #include "includes.h"
26*0Sstevel@tonic-gate
27*0Sstevel@tonic-gate #include <openssl/rand.h>
28*0Sstevel@tonic-gate #include <openssl/crypto.h>
29*0Sstevel@tonic-gate
30*0Sstevel@tonic-gate #include "ssh.h"
31*0Sstevel@tonic-gate #include "misc.h"
32*0Sstevel@tonic-gate #include "xmalloc.h"
33*0Sstevel@tonic-gate #include "atomicio.h"
34*0Sstevel@tonic-gate #include "pathnames.h"
35*0Sstevel@tonic-gate #include "log.h"
36*0Sstevel@tonic-gate
37*0Sstevel@tonic-gate /*
38*0Sstevel@tonic-gate * Portable OpenSSH PRNG seeding:
39*0Sstevel@tonic-gate * If OpenSSL has not "internally seeded" itself (e.g. pulled data from
40*0Sstevel@tonic-gate * /dev/random), then we execute a "ssh-rand-helper" program which
41*0Sstevel@tonic-gate * collects entropy and writes it to stdout. The child program must
42*0Sstevel@tonic-gate * write at least RANDOM_SEED_SIZE bytes. The child is run with stderr
43*0Sstevel@tonic-gate * attached, so error/debugging output should be visible.
44*0Sstevel@tonic-gate *
45*0Sstevel@tonic-gate * XXX: we should tell the child how many bytes we need.
46*0Sstevel@tonic-gate */
47*0Sstevel@tonic-gate
48*0Sstevel@tonic-gate RCSID("$Id: entropy.c,v 1.44 2002/06/09 19:41:48 mouring Exp $");
49*0Sstevel@tonic-gate
50*0Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI"
51*0Sstevel@tonic-gate
52*0Sstevel@tonic-gate #ifndef OPENSSL_PRNG_ONLY
53*0Sstevel@tonic-gate #define RANDOM_SEED_SIZE 48
54*0Sstevel@tonic-gate static uid_t original_uid, original_euid;
55*0Sstevel@tonic-gate #endif
56*0Sstevel@tonic-gate
57*0Sstevel@tonic-gate void
seed_rng(void)58*0Sstevel@tonic-gate seed_rng(void)
59*0Sstevel@tonic-gate {
60*0Sstevel@tonic-gate #ifndef OPENSSL_PRNG_ONLY
61*0Sstevel@tonic-gate int devnull;
62*0Sstevel@tonic-gate int p[2];
63*0Sstevel@tonic-gate pid_t pid;
64*0Sstevel@tonic-gate int ret;
65*0Sstevel@tonic-gate unsigned char buf[RANDOM_SEED_SIZE];
66*0Sstevel@tonic-gate mysig_t old_sigchld;
67*0Sstevel@tonic-gate
68*0Sstevel@tonic-gate if (RAND_status() == 1) {
69*0Sstevel@tonic-gate debug3("RNG is ready, skipping seeding");
70*0Sstevel@tonic-gate return;
71*0Sstevel@tonic-gate }
72*0Sstevel@tonic-gate
73*0Sstevel@tonic-gate debug3("Seeding PRNG from %s", SSH_RAND_HELPER);
74*0Sstevel@tonic-gate
75*0Sstevel@tonic-gate if ((devnull = open("/dev/null", O_RDWR)) == -1)
76*0Sstevel@tonic-gate fatal("Couldn't open /dev/null: %s", strerror(errno));
77*0Sstevel@tonic-gate if (pipe(p) == -1)
78*0Sstevel@tonic-gate fatal("pipe: %s", strerror(errno));
79*0Sstevel@tonic-gate
80*0Sstevel@tonic-gate old_sigchld = mysignal(SIGCHLD, SIG_DFL);
81*0Sstevel@tonic-gate if ((pid = fork()) == -1)
82*0Sstevel@tonic-gate fatal("Couldn't fork: %s", strerror(errno));
83*0Sstevel@tonic-gate if (pid == 0) {
84*0Sstevel@tonic-gate dup2(devnull, STDIN_FILENO);
85*0Sstevel@tonic-gate dup2(p[1], STDOUT_FILENO);
86*0Sstevel@tonic-gate /* Keep stderr open for errors */
87*0Sstevel@tonic-gate close(p[0]);
88*0Sstevel@tonic-gate close(p[1]);
89*0Sstevel@tonic-gate close(devnull);
90*0Sstevel@tonic-gate
91*0Sstevel@tonic-gate if (original_uid != original_euid &&
92*0Sstevel@tonic-gate ( seteuid(getuid()) == -1 ||
93*0Sstevel@tonic-gate setuid(original_uid) == -1) ) {
94*0Sstevel@tonic-gate fprintf(stderr, "(rand child) setuid(%d): %s\n",
95*0Sstevel@tonic-gate original_uid, strerror(errno));
96*0Sstevel@tonic-gate _exit(1);
97*0Sstevel@tonic-gate }
98*0Sstevel@tonic-gate
99*0Sstevel@tonic-gate execl(SSH_RAND_HELPER, "ssh-rand-helper", NULL);
100*0Sstevel@tonic-gate fprintf(stderr, "(rand child) Couldn't exec '%s': %s\n",
101*0Sstevel@tonic-gate SSH_RAND_HELPER, strerror(errno));
102*0Sstevel@tonic-gate _exit(1);
103*0Sstevel@tonic-gate }
104*0Sstevel@tonic-gate
105*0Sstevel@tonic-gate close(devnull);
106*0Sstevel@tonic-gate close(p[1]);
107*0Sstevel@tonic-gate
108*0Sstevel@tonic-gate memset(buf, '\0', sizeof(buf));
109*0Sstevel@tonic-gate ret = atomicio(read, p[0], buf, sizeof(buf));
110*0Sstevel@tonic-gate if (ret == -1)
111*0Sstevel@tonic-gate fatal("Couldn't read from ssh-rand-helper: %s",
112*0Sstevel@tonic-gate strerror(errno));
113*0Sstevel@tonic-gate if (ret != sizeof(buf))
114*0Sstevel@tonic-gate fatal("ssh-rand-helper child produced insufficient data");
115*0Sstevel@tonic-gate
116*0Sstevel@tonic-gate close(p[0]);
117*0Sstevel@tonic-gate
118*0Sstevel@tonic-gate if (waitpid(pid, &ret, 0) == -1)
119*0Sstevel@tonic-gate fatal("Couldn't wait for ssh-rand-helper completion: %s",
120*0Sstevel@tonic-gate strerror(errno));
121*0Sstevel@tonic-gate mysignal(SIGCHLD, old_sigchld);
122*0Sstevel@tonic-gate
123*0Sstevel@tonic-gate /* We don't mind if the child exits upon a SIGPIPE */
124*0Sstevel@tonic-gate if (!WIFEXITED(ret) &&
125*0Sstevel@tonic-gate (!WIFSIGNALED(ret) || WTERMSIG(ret) != SIGPIPE))
126*0Sstevel@tonic-gate fatal("ssh-rand-helper terminated abnormally");
127*0Sstevel@tonic-gate if (WEXITSTATUS(ret) != 0)
128*0Sstevel@tonic-gate fatal("ssh-rand-helper exit with exit status %d", ret);
129*0Sstevel@tonic-gate
130*0Sstevel@tonic-gate RAND_add(buf, sizeof(buf), sizeof(buf));
131*0Sstevel@tonic-gate memset(buf, '\0', sizeof(buf));
132*0Sstevel@tonic-gate
133*0Sstevel@tonic-gate #endif /* OPENSSL_PRNG_ONLY */
134*0Sstevel@tonic-gate if (RAND_status() != 1)
135*0Sstevel@tonic-gate fatal("PRNG is not seeded");
136*0Sstevel@tonic-gate }
137*0Sstevel@tonic-gate
138*0Sstevel@tonic-gate void
init_rng(void)139*0Sstevel@tonic-gate init_rng(void)
140*0Sstevel@tonic-gate {
141*0Sstevel@tonic-gate /*
142*0Sstevel@tonic-gate * OpenSSL version numbers: MNNFFPPS: major minor fix patch status
143*0Sstevel@tonic-gate * We match major, minor, fix and status (not patch)
144*0Sstevel@tonic-gate */
145*0Sstevel@tonic-gate if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L)
146*0Sstevel@tonic-gate fatal("OpenSSL version mismatch. Built against %lx, you "
147*0Sstevel@tonic-gate "have %lx", OPENSSL_VERSION_NUMBER, SSLeay());
148*0Sstevel@tonic-gate
149*0Sstevel@tonic-gate #ifndef OPENSSL_PRNG_ONLY
150*0Sstevel@tonic-gate if ((original_uid = getuid()) == -1)
151*0Sstevel@tonic-gate fatal("getuid: %s", strerror(errno));
152*0Sstevel@tonic-gate if ((original_euid = geteuid()) == -1)
153*0Sstevel@tonic-gate fatal("geteuid: %s", strerror(errno));
154*0Sstevel@tonic-gate #endif
155*0Sstevel@tonic-gate }
156*0Sstevel@tonic-gate
157