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3c0ef626 | 1 | /* |
e9a17296 | 2 | * Copyright (c) 2001 Damien Miller. All rights reserved. |
3c0ef626 | 3 | * |
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. | |
12 | * | |
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 | ||
2e437378 | 27 | #include <sys/types.h> |
28 | #include <sys/wait.h> | |
29 | ||
30 | #ifdef HAVE_SYS_STAT_H | |
31 | # include <sys/stat.h> | |
32 | #endif | |
33 | ||
34 | #ifdef HAVE_FCNTL_H | |
35 | # include <fcntl.h> | |
36 | #endif | |
37 | #include <stdarg.h> | |
38 | #include <unistd.h> | |
39 | #include <signal.h> | |
40 | ||
3c0ef626 | 41 | #include <openssl/rand.h> |
3c0ef626 | 42 | #include <openssl/crypto.h> |
e00da40d | 43 | #include <openssl/err.h> |
3c0ef626 | 44 | |
3c0ef626 | 45 | #include "ssh.h" |
46 | #include "misc.h" | |
47 | #include "xmalloc.h" | |
48 | #include "atomicio.h" | |
49 | #include "pathnames.h" | |
50 | #include "log.h" | |
e00da40d | 51 | #include "buffer.h" |
3c0ef626 | 52 | |
3c0ef626 | 53 | /* |
e9a17296 | 54 | * Portable OpenSSH PRNG seeding: |
416fd2a8 | 55 | * If OpenSSL has not "internally seeded" itself (e.g. pulled data from |
56 | * /dev/random), then we execute a "ssh-rand-helper" program which | |
57 | * collects entropy and writes it to stdout. The child program must | |
e9a17296 | 58 | * write at least RANDOM_SEED_SIZE bytes. The child is run with stderr |
59 | * attached, so error/debugging output should be visible. | |
60 | * | |
61 | * XXX: we should tell the child how many bytes we need. | |
3c0ef626 | 62 | */ |
3c0ef626 | 63 | |
e9a17296 | 64 | #ifndef OPENSSL_PRNG_ONLY |
65 | #define RANDOM_SEED_SIZE 48 | |
66 | static uid_t original_uid, original_euid; | |
67 | #endif | |
3c0ef626 | 68 | |
69 | void | |
e9a17296 | 70 | seed_rng(void) |
3c0ef626 | 71 | { |
e9a17296 | 72 | #ifndef OPENSSL_PRNG_ONLY |
73 | int devnull; | |
3c0ef626 | 74 | int p[2]; |
3c0ef626 | 75 | pid_t pid; |
e9a17296 | 76 | int ret; |
77 | unsigned char buf[RANDOM_SEED_SIZE]; | |
2980ea68 | 78 | mysig_t old_sigchld; |
3c0ef626 | 79 | |
e9a17296 | 80 | if (RAND_status() == 1) { |
81 | debug3("RNG is ready, skipping seeding"); | |
3c0ef626 | 82 | return; |
3c0ef626 | 83 | } |
3c0ef626 | 84 | |
2980ea68 | 85 | debug3("Seeding PRNG from %s", SSH_RAND_HELPER); |
3c0ef626 | 86 | |
e9a17296 | 87 | if ((devnull = open("/dev/null", O_RDWR)) == -1) |
88 | fatal("Couldn't open /dev/null: %s", strerror(errno)); | |
89 | if (pipe(p) == -1) | |
90 | fatal("pipe: %s", strerror(errno)); | |
91 | ||
70791e56 | 92 | old_sigchld = signal(SIGCHLD, SIG_DFL); |
e9a17296 | 93 | if ((pid = fork()) == -1) |
94 | fatal("Couldn't fork: %s", strerror(errno)); | |
95 | if (pid == 0) { | |
96 | dup2(devnull, STDIN_FILENO); | |
97 | dup2(p[1], STDOUT_FILENO); | |
98 | /* Keep stderr open for errors */ | |
99 | close(p[0]); | |
100 | close(p[1]); | |
101 | close(devnull); | |
102 | ||
416fd2a8 | 103 | if (original_uid != original_euid && |
104 | ( seteuid(getuid()) == -1 || | |
2980ea68 | 105 | setuid(original_uid) == -1) ) { |
416fd2a8 | 106 | fprintf(stderr, "(rand child) setuid(%li): %s\n", |
70791e56 | 107 | (long int)original_uid, strerror(errno)); |
e9a17296 | 108 | _exit(1); |
3c0ef626 | 109 | } |
416fd2a8 | 110 | |
e9a17296 | 111 | execl(SSH_RAND_HELPER, "ssh-rand-helper", NULL); |
416fd2a8 | 112 | fprintf(stderr, "(rand child) Couldn't exec '%s': %s\n", |
e9a17296 | 113 | SSH_RAND_HELPER, strerror(errno)); |
114 | _exit(1); | |
3c0ef626 | 115 | } |
116 | ||
e9a17296 | 117 | close(devnull); |
118 | close(p[1]); | |
3c0ef626 | 119 | |
e9a17296 | 120 | memset(buf, '\0', sizeof(buf)); |
121 | ret = atomicio(read, p[0], buf, sizeof(buf)); | |
122 | if (ret == -1) | |
123 | fatal("Couldn't read from ssh-rand-helper: %s", | |
124 | strerror(errno)); | |
125 | if (ret != sizeof(buf)) | |
126 | fatal("ssh-rand-helper child produced insufficient data"); | |
3c0ef626 | 127 | |
e9a17296 | 128 | close(p[0]); |
3c0ef626 | 129 | |
e9a17296 | 130 | if (waitpid(pid, &ret, 0) == -1) |
34fee935 | 131 | fatal("Couldn't wait for ssh-rand-helper completion: %s", |
132 | strerror(errno)); | |
70791e56 | 133 | signal(SIGCHLD, old_sigchld); |
3c0ef626 | 134 | |
e9a17296 | 135 | /* We don't mind if the child exits upon a SIGPIPE */ |
416fd2a8 | 136 | if (!WIFEXITED(ret) && |
e9a17296 | 137 | (!WIFSIGNALED(ret) || WTERMSIG(ret) != SIGPIPE)) |
138 | fatal("ssh-rand-helper terminated abnormally"); | |
139 | if (WEXITSTATUS(ret) != 0) | |
140 | fatal("ssh-rand-helper exit with exit status %d", ret); | |
3c0ef626 | 141 | |
e9a17296 | 142 | RAND_add(buf, sizeof(buf), sizeof(buf)); |
143 | memset(buf, '\0', sizeof(buf)); | |
3c0ef626 | 144 | |
e9a17296 | 145 | #endif /* OPENSSL_PRNG_ONLY */ |
146 | if (RAND_status() != 1) | |
147 | fatal("PRNG is not seeded"); | |
3c0ef626 | 148 | } |
149 | ||
150 | void | |
416fd2a8 | 151 | init_rng(void) |
3c0ef626 | 152 | { |
3c0ef626 | 153 | /* |
e9a17296 | 154 | * OpenSSL version numbers: MNNFFPPS: major minor fix patch status |
155 | * We match major, minor, fix and status (not patch) | |
3c0ef626 | 156 | */ |
e9a17296 | 157 | if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L) |
158 | fatal("OpenSSL version mismatch. Built against %lx, you " | |
159 | "have %lx", OPENSSL_VERSION_NUMBER, SSLeay()); | |
3c0ef626 | 160 | |
e9a17296 | 161 | #ifndef OPENSSL_PRNG_ONLY |
e00da40d | 162 | original_uid = getuid(); |
163 | original_euid = geteuid(); | |
e9a17296 | 164 | #endif |
3c0ef626 | 165 | } |
166 | ||
e00da40d | 167 | #ifndef OPENSSL_PRNG_ONLY |
168 | void | |
169 | rexec_send_rng_seed(Buffer *m) | |
170 | { | |
171 | u_char buf[RANDOM_SEED_SIZE]; | |
172 | ||
173 | if (RAND_bytes(buf, sizeof(buf)) <= 0) { | |
174 | error("Couldn't obtain random bytes (error %ld)", | |
175 | ERR_get_error()); | |
176 | buffer_put_string(m, "", 0); | |
177 | } else | |
178 | buffer_put_string(m, buf, sizeof(buf)); | |
179 | } | |
180 | ||
181 | void | |
182 | rexec_recv_rng_seed(Buffer *m) | |
183 | { | |
184 | u_char *buf; | |
185 | u_int len; | |
186 | ||
187 | buf = buffer_get_string_ret(m, &len); | |
188 | if (buf != NULL) { | |
189 | debug3("rexec_recv_rng_seed: seeding rng with %u bytes", len); | |
190 | RAND_add(buf, len, len); | |
191 | } | |
192 | } | |
193 | #endif |