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 #define RANDOM_SEED_SIZE 48 28 29 #ifdef WITH_OPENSSL 30 31 #include <sys/types.h> 32 33 #include <errno.h> 34 #include <signal.h> 35 #include <stdlib.h> 36 #include <string.h> 37 #include <unistd.h> 38 39 #include <openssl/rand.h> 40 #include <openssl/crypto.h> 41 #include <openssl/err.h> 42 43 #include "openbsd-compat/openssl-compat.h" 44 45 #include "ssh.h" 46 #include "misc.h" 47 #include "xmalloc.h" 48 #include "atomicio.h" 49 #include "pathnames.h" 50 #include "log.h" 51 #include "sshbuf.h" 52 #include "ssherr.h" 53 54 /* 55 * Portable OpenSSH PRNG seeding: 56 * If OpenSSL has not "internally seeded" itself (e.g. pulled data from 57 * /dev/random), then collect RANDOM_SEED_SIZE bytes of randomness from 58 * PRNGd. 59 */ 60 #ifndef OPENSSL_PRNG_ONLY 61 62 void 63 rexec_send_rng_seed(struct sshbuf *m) 64 { 65 u_char buf[RANDOM_SEED_SIZE]; 66 size_t len = sizeof(buf); 67 int r; 68 69 if (RAND_bytes(buf, sizeof(buf)) <= 0) { 70 error("Couldn't obtain random bytes (error %ld)", 71 ERR_get_error()); 72 len = 0; 73 } 74 if ((r = sshbuf_put_string(m, buf, len)) != 0) 75 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 76 explicit_bzero(buf, sizeof(buf)); 77 } 78 79 void 80 rexec_recv_rng_seed(struct sshbuf *m) 81 { 82 const u_char *buf = NULL; 83 size_t len = 0; 84 int r; 85 86 if ((r = sshbuf_get_string_direct(m, &buf, &len)) != 0) 87 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 88 89 debug3("rexec_recv_rng_seed: seeding rng with %lu bytes", 90 (unsigned long)len); 91 RAND_add(buf, len, len); 92 } 93 #endif /* OPENSSL_PRNG_ONLY */ 94 95 void 96 seed_rng(void) 97 { 98 unsigned char buf[RANDOM_SEED_SIZE]; 99 100 /* Initialise libcrypto */ 101 ssh_libcrypto_init(); 102 103 if (!ssh_compatible_openssl(OPENSSL_VERSION_NUMBER, 104 OpenSSL_version_num())) 105 fatal("OpenSSL version mismatch. Built against %lx, you " 106 "have %lx", (u_long)OPENSSL_VERSION_NUMBER, 107 OpenSSL_version_num()); 108 109 #ifndef OPENSSL_PRNG_ONLY 110 if (RAND_status() == 1) 111 debug3("RNG is ready, skipping seeding"); 112 else { 113 if (seed_from_prngd(buf, sizeof(buf)) == -1) 114 fatal("Could not obtain seed from PRNGd"); 115 RAND_add(buf, sizeof(buf), sizeof(buf)); 116 } 117 #endif /* OPENSSL_PRNG_ONLY */ 118 119 if (RAND_status() != 1) 120 fatal("PRNG is not seeded"); 121 122 /* Ensure arc4random() is primed */ 123 arc4random_buf(buf, sizeof(buf)); 124 explicit_bzero(buf, sizeof(buf)); 125 } 126 127 #else /* WITH_OPENSSL */ 128 129 #include <stdlib.h> 130 #include <string.h> 131 132 /* Actual initialisation is handled in arc4random() */ 133 void 134 seed_rng(void) 135 { 136 unsigned char buf[RANDOM_SEED_SIZE]; 137 138 /* Ensure arc4random() is primed */ 139 arc4random_buf(buf, sizeof(buf)); 140 explicit_bzero(buf, sizeof(buf)); 141 } 142 143 #endif /* WITH_OPENSSL */ 144