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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 | ||
27 | #include <openssl/rand.h> | |
3c0ef626 | 28 | #include <openssl/crypto.h> |
29 | ||
3c0ef626 | 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 | ||
3c0ef626 | 37 | /* |
e9a17296 | 38 | * Portable OpenSSH PRNG seeding: |
416fd2a8 | 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 | |
e9a17296 | 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. | |
3c0ef626 | 46 | */ |
3c0ef626 | 47 | |
e9a17296 | 48 | RCSID("$Id$"); |
3c0ef626 | 49 | |
e9a17296 | 50 | #ifndef OPENSSL_PRNG_ONLY |
51 | #define RANDOM_SEED_SIZE 48 | |
52 | static uid_t original_uid, original_euid; | |
53 | #endif | |
3c0ef626 | 54 | |
55 | void | |
e9a17296 | 56 | seed_rng(void) |
3c0ef626 | 57 | { |
e9a17296 | 58 | #ifndef OPENSSL_PRNG_ONLY |
59 | int devnull; | |
3c0ef626 | 60 | int p[2]; |
3c0ef626 | 61 | pid_t pid; |
e9a17296 | 62 | int ret; |
63 | unsigned char buf[RANDOM_SEED_SIZE]; | |
2980ea68 | 64 | mysig_t old_sigchld; |
3c0ef626 | 65 | |
e9a17296 | 66 | if (RAND_status() == 1) { |
67 | debug3("RNG is ready, skipping seeding"); | |
3c0ef626 | 68 | return; |
3c0ef626 | 69 | } |
3c0ef626 | 70 | |
2980ea68 | 71 | debug3("Seeding PRNG from %s", SSH_RAND_HELPER); |
3c0ef626 | 72 | |
e9a17296 | 73 | if ((devnull = open("/dev/null", O_RDWR)) == -1) |
74 | fatal("Couldn't open /dev/null: %s", strerror(errno)); | |
75 | if (pipe(p) == -1) | |
76 | fatal("pipe: %s", strerror(errno)); | |
77 | ||
70791e56 | 78 | old_sigchld = signal(SIGCHLD, SIG_DFL); |
e9a17296 | 79 | if ((pid = fork()) == -1) |
80 | fatal("Couldn't fork: %s", strerror(errno)); | |
81 | if (pid == 0) { | |
82 | dup2(devnull, STDIN_FILENO); | |
83 | dup2(p[1], STDOUT_FILENO); | |
84 | /* Keep stderr open for errors */ | |
85 | close(p[0]); | |
86 | close(p[1]); | |
87 | close(devnull); | |
88 | ||
416fd2a8 | 89 | if (original_uid != original_euid && |
90 | ( seteuid(getuid()) == -1 || | |
2980ea68 | 91 | setuid(original_uid) == -1) ) { |
416fd2a8 | 92 | fprintf(stderr, "(rand child) setuid(%li): %s\n", |
70791e56 | 93 | (long int)original_uid, strerror(errno)); |
e9a17296 | 94 | _exit(1); |
3c0ef626 | 95 | } |
416fd2a8 | 96 | |
e9a17296 | 97 | execl(SSH_RAND_HELPER, "ssh-rand-helper", NULL); |
416fd2a8 | 98 | fprintf(stderr, "(rand child) Couldn't exec '%s': %s\n", |
e9a17296 | 99 | SSH_RAND_HELPER, strerror(errno)); |
100 | _exit(1); | |
3c0ef626 | 101 | } |
102 | ||
e9a17296 | 103 | close(devnull); |
104 | close(p[1]); | |
3c0ef626 | 105 | |
e9a17296 | 106 | memset(buf, '\0', sizeof(buf)); |
107 | ret = atomicio(read, p[0], buf, sizeof(buf)); | |
108 | if (ret == -1) | |
109 | fatal("Couldn't read from ssh-rand-helper: %s", | |
110 | strerror(errno)); | |
111 | if (ret != sizeof(buf)) | |
112 | fatal("ssh-rand-helper child produced insufficient data"); | |
3c0ef626 | 113 | |
e9a17296 | 114 | close(p[0]); |
3c0ef626 | 115 | |
e9a17296 | 116 | if (waitpid(pid, &ret, 0) == -1) |
416fd2a8 | 117 | fatal("Couldn't wait for ssh-rand-helper completion: %s", |
ff2d7a98 | 118 | strerror(errno)); |
70791e56 | 119 | signal(SIGCHLD, old_sigchld); |
3c0ef626 | 120 | |
e9a17296 | 121 | /* We don't mind if the child exits upon a SIGPIPE */ |
416fd2a8 | 122 | if (!WIFEXITED(ret) && |
e9a17296 | 123 | (!WIFSIGNALED(ret) || WTERMSIG(ret) != SIGPIPE)) |
124 | fatal("ssh-rand-helper terminated abnormally"); | |
125 | if (WEXITSTATUS(ret) != 0) | |
126 | fatal("ssh-rand-helper exit with exit status %d", ret); | |
3c0ef626 | 127 | |
e9a17296 | 128 | RAND_add(buf, sizeof(buf), sizeof(buf)); |
129 | memset(buf, '\0', sizeof(buf)); | |
3c0ef626 | 130 | |
e9a17296 | 131 | #endif /* OPENSSL_PRNG_ONLY */ |
132 | if (RAND_status() != 1) | |
133 | fatal("PRNG is not seeded"); | |
3c0ef626 | 134 | } |
135 | ||
136 | void | |
416fd2a8 | 137 | init_rng(void) |
3c0ef626 | 138 | { |
3c0ef626 | 139 | /* |
e9a17296 | 140 | * OpenSSL version numbers: MNNFFPPS: major minor fix patch status |
141 | * We match major, minor, fix and status (not patch) | |
3c0ef626 | 142 | */ |
e9a17296 | 143 | if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L) |
144 | fatal("OpenSSL version mismatch. Built against %lx, you " | |
145 | "have %lx", OPENSSL_VERSION_NUMBER, SSLeay()); | |
3c0ef626 | 146 | |
e9a17296 | 147 | #ifndef OPENSSL_PRNG_ONLY |
148 | if ((original_uid = getuid()) == -1) | |
149 | fatal("getuid: %s", strerror(errno)); | |
150 | if ((original_euid = geteuid()) == -1) | |
151 | fatal("geteuid: %s", strerror(errno)); | |
152 | #endif | |
3c0ef626 | 153 | } |
154 |