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bfc9a610 | 1 | /* |
46058ce2 | 2 | * Copyright (c) 2001 Damien Miller. All rights reserved. |
bfc9a610 | 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. | |
bfc9a610 | 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 | ||
32b0131a | 27 | #include <sys/types.h> |
28 | #include <sys/wait.h> | |
29 | ||
35484284 | 30 | #include <openssl/rand.h> |
c7c72446 | 31 | #include <openssl/crypto.h> |
72f02ae7 | 32 | #include <openssl/err.h> |
bfc9a610 | 33 | |
42f11eb2 | 34 | #include "ssh.h" |
e1a023df | 35 | #include "misc.h" |
42f11eb2 | 36 | #include "xmalloc.h" |
37 | #include "atomicio.h" | |
effa6591 | 38 | #include "pathnames.h" |
42f11eb2 | 39 | #include "log.h" |
72f02ae7 | 40 | #include "buffer.h" |
41 | #include "bufaux.h" | |
42f11eb2 | 42 | |
48c99b2c | 43 | /* |
46058ce2 | 44 | * Portable OpenSSH PRNG seeding: |
aff51935 | 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 | |
46058ce2 | 48 | * write at least RANDOM_SEED_SIZE bytes. The child is run with stderr |
49 | * attached, so error/debugging output should be visible. | |
50 | * | |
51 | * XXX: we should tell the child how many bytes we need. | |
48c99b2c | 52 | */ |
2b87da3b | 53 | |
f1b0ecc3 | 54 | #ifndef OPENSSL_PRNG_ONLY |
55 | #define RANDOM_SEED_SIZE 48 | |
46058ce2 | 56 | static uid_t original_uid, original_euid; |
f1b0ecc3 | 57 | #endif |
48c99b2c | 58 | |
e339aa53 | 59 | void |
46058ce2 | 60 | seed_rng(void) |
bfc9a610 | 61 | { |
f1b0ecc3 | 62 | #ifndef OPENSSL_PRNG_ONLY |
46058ce2 | 63 | int devnull; |
bfc9a610 | 64 | int p[2]; |
65 | pid_t pid; | |
46058ce2 | 66 | int ret; |
67 | unsigned char buf[RANDOM_SEED_SIZE]; | |
6dc63b4f | 68 | mysig_t old_sigchld; |
bfc9a610 | 69 | |
46058ce2 | 70 | if (RAND_status() == 1) { |
71 | debug3("RNG is ready, skipping seeding"); | |
b7a87eea | 72 | return; |
73 | } | |
74 | ||
dc254471 | 75 | debug3("Seeding PRNG from %s", SSH_RAND_HELPER); |
d3083fbd | 76 | |
46058ce2 | 77 | if ((devnull = open("/dev/null", O_RDWR)) == -1) |
78 | fatal("Couldn't open /dev/null: %s", strerror(errno)); | |
79 | if (pipe(p) == -1) | |
80 | fatal("pipe: %s", strerror(errno)); | |
81 | ||
f00d1f78 | 82 | old_sigchld = signal(SIGCHLD, SIG_DFL); |
46058ce2 | 83 | if ((pid = fork()) == -1) |
84 | fatal("Couldn't fork: %s", strerror(errno)); | |
85 | if (pid == 0) { | |
86 | dup2(devnull, STDIN_FILENO); | |
87 | dup2(p[1], STDOUT_FILENO); | |
88 | /* Keep stderr open for errors */ | |
89 | close(p[0]); | |
90 | close(p[1]); | |
91 | close(devnull); | |
92 | ||
aff51935 | 93 | if (original_uid != original_euid && |
94 | ( seteuid(getuid()) == -1 || | |
ac033f8c | 95 | setuid(original_uid) == -1) ) { |
aff51935 | 96 | fprintf(stderr, "(rand child) setuid(%li): %s\n", |
7be625e1 | 97 | (long int)original_uid, strerror(errno)); |
46058ce2 | 98 | _exit(1); |
48c99b2c | 99 | } |
b6453d99 | 100 | |
46058ce2 | 101 | execl(SSH_RAND_HELPER, "ssh-rand-helper", NULL); |
aff51935 | 102 | fprintf(stderr, "(rand child) Couldn't exec '%s': %s\n", |
46058ce2 | 103 | SSH_RAND_HELPER, strerror(errno)); |
104 | _exit(1); | |
d3083fbd | 105 | } |
106 | ||
46058ce2 | 107 | close(devnull); |
108 | close(p[1]); | |
2b87da3b | 109 | |
46058ce2 | 110 | memset(buf, '\0', sizeof(buf)); |
111 | ret = atomicio(read, p[0], buf, sizeof(buf)); | |
112 | if (ret == -1) | |
113 | fatal("Couldn't read from ssh-rand-helper: %s", | |
114 | strerror(errno)); | |
115 | if (ret != sizeof(buf)) | |
116 | fatal("ssh-rand-helper child produced insufficient data"); | |
a64009ad | 117 | |
46058ce2 | 118 | close(p[0]); |
264dce47 | 119 | |
46058ce2 | 120 | if (waitpid(pid, &ret, 0) == -1) |
98c044d0 | 121 | fatal("Couldn't wait for ssh-rand-helper completion: %s", |
122 | strerror(errno)); | |
f00d1f78 | 123 | signal(SIGCHLD, old_sigchld); |
b7a87eea | 124 | |
46058ce2 | 125 | /* We don't mind if the child exits upon a SIGPIPE */ |
aff51935 | 126 | if (!WIFEXITED(ret) && |
46058ce2 | 127 | (!WIFSIGNALED(ret) || WTERMSIG(ret) != SIGPIPE)) |
128 | fatal("ssh-rand-helper terminated abnormally"); | |
129 | if (WEXITSTATUS(ret) != 0) | |
130 | fatal("ssh-rand-helper exit with exit status %d", ret); | |
a64009ad | 131 | |
46058ce2 | 132 | RAND_add(buf, sizeof(buf), sizeof(buf)); |
133 | memset(buf, '\0', sizeof(buf)); | |
f1b0ecc3 | 134 | |
135 | #endif /* OPENSSL_PRNG_ONLY */ | |
136 | if (RAND_status() != 1) | |
137 | fatal("PRNG is not seeded"); | |
264dce47 | 138 | } |
ad85db64 | 139 | |
e339aa53 | 140 | void |
aff51935 | 141 | init_rng(void) |
264dce47 | 142 | { |
e9a13ac1 | 143 | /* |
46058ce2 | 144 | * OpenSSL version numbers: MNNFFPPS: major minor fix patch status |
145 | * We match major, minor, fix and status (not patch) | |
e9a13ac1 | 146 | */ |
46058ce2 | 147 | if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L) |
148 | fatal("OpenSSL version mismatch. Built against %lx, you " | |
149 | "have %lx", OPENSSL_VERSION_NUMBER, SSLeay()); | |
264dce47 | 150 | |
f1b0ecc3 | 151 | #ifndef OPENSSL_PRNG_ONLY |
759ab0d9 | 152 | original_uid = getuid(); |
153 | original_euid = geteuid(); | |
f1b0ecc3 | 154 | #endif |
bfc9a610 | 155 | } |
f1b0ecc3 | 156 | |
72f02ae7 | 157 | #ifndef OPENSSL_PRNG_ONLY |
158 | void | |
159 | rexec_send_rng_seed(Buffer *m) | |
160 | { | |
161 | u_char buf[RANDOM_SEED_SIZE]; | |
162 | ||
163 | if (RAND_bytes(buf, sizeof(buf)) <= 0) { | |
164 | error("Couldn't obtain random bytes (error %ld)", | |
165 | ERR_get_error()); | |
166 | buffer_put_string(m, "", 0); | |
167 | } else | |
168 | buffer_put_string(m, buf, sizeof(buf)); | |
169 | } | |
170 | ||
171 | void | |
172 | rexec_recv_rng_seed(Buffer *m) | |
173 | { | |
4ebacf50 | 174 | u_char *buf; |
72f02ae7 | 175 | u_int len; |
176 | ||
177 | buf = buffer_get_string_ret(m, &len); | |
178 | if (buf != NULL) { | |
179 | debug3("rexec_recv_rng_seed: seeding rng with %u bytes", len); | |
180 | RAND_add(buf, len, len); | |
181 | } | |
182 | } | |
183 | #endif |