]>
Commit | Line | Data |
---|---|---|
1 | /* | |
2 | * Copyright (c) 2001 Damien Miller. All rights reserved. | |
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 | ||
27 | #include <openssl/rand.h> | |
28 | #include <openssl/crypto.h> | |
29 | ||
30 | #include "ssh.h" | |
31 | #include "misc.h" | |
32 | #include "xmalloc.h" | |
33 | #include "atomicio.h" | |
34 | #include "pathnames.h" | |
35 | #include "log.h" | |
36 | ||
37 | /* | |
38 | * Portable OpenSSH PRNG seeding: | |
39 | * If OpenSSL has not "internally seeded" itself (e.g. pulled data from | |
40 | * /dev/random), then we execute a "ssh-rand-helper" program which | |
41 | * collects entropy and writes it to stdout. The child program must | |
42 | * write at least RANDOM_SEED_SIZE bytes. The child is run with stderr | |
43 | * attached, so error/debugging output should be visible. | |
44 | * | |
45 | * XXX: we should tell the child how many bytes we need. | |
46 | */ | |
47 | ||
48 | RCSID("$Id$"); | |
49 | ||
50 | #ifndef OPENSSL_PRNG_ONLY | |
51 | #define RANDOM_SEED_SIZE 48 | |
52 | static uid_t original_uid, original_euid; | |
53 | #endif | |
54 | ||
55 | void | |
56 | seed_rng(void) | |
57 | { | |
58 | #ifndef OPENSSL_PRNG_ONLY | |
59 | int devnull; | |
60 | int p[2]; | |
61 | pid_t pid; | |
62 | int ret; | |
63 | unsigned char buf[RANDOM_SEED_SIZE]; | |
64 | ||
65 | if (RAND_status() == 1) { | |
66 | debug3("RNG is ready, skipping seeding"); | |
67 | return; | |
68 | } | |
69 | ||
70 | debug3("Seeing PRNG from %s", SSH_RAND_HELPER); | |
71 | ||
72 | if ((devnull = open("/dev/null", O_RDWR)) == -1) | |
73 | fatal("Couldn't open /dev/null: %s", strerror(errno)); | |
74 | if (pipe(p) == -1) | |
75 | fatal("pipe: %s", strerror(errno)); | |
76 | ||
77 | if ((pid = fork()) == -1) | |
78 | fatal("Couldn't fork: %s", strerror(errno)); | |
79 | if (pid == 0) { | |
80 | dup2(devnull, STDIN_FILENO); | |
81 | dup2(p[1], STDOUT_FILENO); | |
82 | /* Keep stderr open for errors */ | |
83 | close(p[0]); | |
84 | close(p[1]); | |
85 | close(devnull); | |
86 | ||
87 | if (original_uid != original_euid && | |
88 | setuid(original_uid) == -1) { | |
89 | fprintf(stderr, "(rand child) setuid: %s\n", | |
90 | strerror(errno)); | |
91 | _exit(1); | |
92 | } | |
93 | ||
94 | execl(SSH_RAND_HELPER, "ssh-rand-helper", NULL); | |
95 | fprintf(stderr, "(rand child) Couldn't exec '%s': %s\n", | |
96 | SSH_RAND_HELPER, strerror(errno)); | |
97 | _exit(1); | |
98 | } | |
99 | ||
100 | close(devnull); | |
101 | close(p[1]); | |
102 | ||
103 | memset(buf, '\0', sizeof(buf)); | |
104 | ret = atomicio(read, p[0], buf, sizeof(buf)); | |
105 | if (ret == -1) | |
106 | fatal("Couldn't read from ssh-rand-helper: %s", | |
107 | strerror(errno)); | |
108 | if (ret != sizeof(buf)) | |
109 | fatal("ssh-rand-helper child produced insufficient data"); | |
110 | ||
111 | close(p[0]); | |
112 | ||
113 | if (waitpid(pid, &ret, 0) == -1) | |
114 | fatal("Couldn't wait for ssh-rand-helper completion: %s", | |
115 | strerror(errno)); | |
116 | ||
117 | /* We don't mind if the child exits upon a SIGPIPE */ | |
118 | if (!WIFEXITED(ret) && | |
119 | (!WIFSIGNALED(ret) || WTERMSIG(ret) != SIGPIPE)) | |
120 | fatal("ssh-rand-helper terminated abnormally"); | |
121 | if (WEXITSTATUS(ret) != 0) | |
122 | fatal("ssh-rand-helper exit with exit status %d", ret); | |
123 | ||
124 | RAND_add(buf, sizeof(buf), sizeof(buf)); | |
125 | memset(buf, '\0', sizeof(buf)); | |
126 | ||
127 | #endif /* OPENSSL_PRNG_ONLY */ | |
128 | if (RAND_status() != 1) | |
129 | fatal("PRNG is not seeded"); | |
130 | } | |
131 | ||
132 | void | |
133 | init_rng(void) | |
134 | { | |
135 | /* | |
136 | * OpenSSL version numbers: MNNFFPPS: major minor fix patch status | |
137 | * We match major, minor, fix and status (not patch) | |
138 | */ | |
139 | if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L) | |
140 | fatal("OpenSSL version mismatch. Built against %lx, you " | |
141 | "have %lx", OPENSSL_VERSION_NUMBER, SSLeay()); | |
142 | ||
143 | #ifndef OPENSSL_PRNG_ONLY | |
144 | if ((original_uid = getuid()) == -1) | |
145 | fatal("getuid: %s", strerror(errno)); | |
146 | if ((original_euid = geteuid()) == -1) | |
147 | fatal("geteuid: %s", strerror(errno)); | |
148 | #endif | |
149 | } | |
150 |