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 #include <sys/socket.h> 33 #ifdef HAVE_SYS_UN_H 34 # include <sys/un.h> 35 #endif 36 37 #include <netinet/in.h> 38 #include <arpa/inet.h> 39 40 #include <errno.h> 41 #include <signal.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include <unistd.h> 45 #include <stddef.h> /* for offsetof */ 46 47 #include <openssl/rand.h> 48 #include <openssl/crypto.h> 49 #include <openssl/err.h> 50 51 #include "openbsd-compat/openssl-compat.h" 52 53 #include "ssh.h" 54 #include "misc.h" 55 #include "xmalloc.h" 56 #include "atomicio.h" 57 #include "pathnames.h" 58 #include "log.h" 59 #include "sshbuf.h" 60 #include "ssherr.h" 61 62 /* 63 * Portable OpenSSH PRNG seeding: 64 * If OpenSSL has not "internally seeded" itself (e.g. pulled data from 65 * /dev/random), then collect RANDOM_SEED_SIZE bytes of randomness from 66 * PRNGd. 67 */ 68 #ifndef OPENSSL_PRNG_ONLY 69 70 /* 71 * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon 72 * listening either on 'tcp_port', or via Unix domain socket at * 73 * 'socket_path'. 74 * Either a non-zero tcp_port or a non-null socket_path must be 75 * supplied. 76 * Returns 0 on success, -1 on error 77 */ 78 int 79 get_random_bytes_prngd(unsigned char *buf, int len, 80 unsigned short tcp_port, char *socket_path) 81 { 82 int fd, addr_len, rval, errors; 83 u_char msg[2]; 84 struct sockaddr_storage addr; 85 struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr; 86 struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr; 87 sshsig_t old_sigpipe; 88 89 /* Sanity checks */ 90 if (socket_path == NULL && tcp_port == 0) 91 fatal("You must specify a port or a socket"); 92 if (socket_path != NULL && 93 strlen(socket_path) >= sizeof(addr_un->sun_path)) 94 fatal("Random pool path is too long"); 95 if (len <= 0 || len > 255) 96 fatal("Too many bytes (%d) to read from PRNGD", len); 97 98 memset(&addr, '\0', sizeof(addr)); 99 100 if (tcp_port != 0) { 101 addr_in->sin_family = AF_INET; 102 addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK); 103 addr_in->sin_port = htons(tcp_port); 104 addr_len = sizeof(*addr_in); 105 } else { 106 addr_un->sun_family = AF_UNIX; 107 strlcpy(addr_un->sun_path, socket_path, 108 sizeof(addr_un->sun_path)); 109 addr_len = offsetof(struct sockaddr_un, sun_path) + 110 strlen(socket_path) + 1; 111 } 112 113 old_sigpipe = ssh_signal(SIGPIPE, SIG_IGN); 114 115 errors = 0; 116 rval = -1; 117 reopen: 118 fd = socket(addr.ss_family, SOCK_STREAM, 0); 119 if (fd == -1) { 120 error("Couldn't create socket: %s", strerror(errno)); 121 goto done; 122 } 123 124 if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { 125 if (tcp_port != 0) { 126 error("Couldn't connect to PRNGD port %d: %s", 127 tcp_port, strerror(errno)); 128 } else { 129 error("Couldn't connect to PRNGD socket \"%s\": %s", 130 addr_un->sun_path, strerror(errno)); 131 } 132 goto done; 133 } 134 135 /* Send blocking read request to PRNGD */ 136 msg[0] = 0x02; 137 msg[1] = len; 138 139 if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) { 140 if (errno == EPIPE && errors < 10) { 141 close(fd); 142 errors++; 143 goto reopen; 144 } 145 error("Couldn't write to PRNGD socket: %s", 146 strerror(errno)); 147 goto done; 148 } 149 150 if (atomicio(read, fd, buf, len) != (size_t)len) { 151 if (errno == EPIPE && errors < 10) { 152 close(fd); 153 errors++; 154 goto reopen; 155 } 156 error("Couldn't read from PRNGD socket: %s", 157 strerror(errno)); 158 goto done; 159 } 160 161 rval = 0; 162 done: 163 ssh_signal(SIGPIPE, old_sigpipe); 164 if (fd != -1) 165 close(fd); 166 return rval; 167 } 168 169 static int 170 seed_from_prngd(unsigned char *buf, size_t bytes) 171 { 172 #ifdef PRNGD_PORT 173 debug("trying egd/prngd port %d", PRNGD_PORT); 174 if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0) 175 return 0; 176 #endif 177 #ifdef PRNGD_SOCKET 178 debug("trying egd/prngd socket %s", PRNGD_SOCKET); 179 if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0) 180 return 0; 181 #endif 182 return -1; 183 } 184 185 void 186 rexec_send_rng_seed(struct sshbuf *m) 187 { 188 u_char buf[RANDOM_SEED_SIZE]; 189 size_t len = sizeof(buf); 190 int r; 191 192 if (RAND_bytes(buf, sizeof(buf)) <= 0) { 193 error("Couldn't obtain random bytes (error %ld)", 194 ERR_get_error()); 195 len = 0; 196 } 197 if ((r = sshbuf_put_string(m, buf, len)) != 0) 198 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 199 explicit_bzero(buf, sizeof(buf)); 200 } 201 202 void 203 rexec_recv_rng_seed(struct sshbuf *m) 204 { 205 const u_char *buf = NULL; 206 size_t len = 0; 207 int r; 208 209 if ((r = sshbuf_get_string_direct(m, &buf, &len)) != 0) 210 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 211 212 debug3("rexec_recv_rng_seed: seeding rng with %lu bytes", 213 (unsigned long)len); 214 RAND_add(buf, len, len); 215 } 216 #endif /* OPENSSL_PRNG_ONLY */ 217 218 void 219 seed_rng(void) 220 { 221 unsigned char buf[RANDOM_SEED_SIZE]; 222 223 /* Initialise libcrypto */ 224 ssh_libcrypto_init(); 225 226 if (!ssh_compatible_openssl(OPENSSL_VERSION_NUMBER, 227 OpenSSL_version_num())) 228 fatal("OpenSSL version mismatch. Built against %lx, you " 229 "have %lx", (u_long)OPENSSL_VERSION_NUMBER, 230 OpenSSL_version_num()); 231 232 #ifndef OPENSSL_PRNG_ONLY 233 if (RAND_status() == 1) 234 debug3("RNG is ready, skipping seeding"); 235 else { 236 if (seed_from_prngd(buf, sizeof(buf)) == -1) 237 fatal("Could not obtain seed from PRNGd"); 238 RAND_add(buf, sizeof(buf), sizeof(buf)); 239 } 240 #endif /* OPENSSL_PRNG_ONLY */ 241 242 if (RAND_status() != 1) 243 fatal("PRNG is not seeded"); 244 245 /* Ensure arc4random() is primed */ 246 arc4random_buf(buf, sizeof(buf)); 247 explicit_bzero(buf, sizeof(buf)); 248 } 249 250 #else /* WITH_OPENSSL */ 251 252 #include <stdlib.h> 253 #include <string.h> 254 255 /* Actual initialisation is handled in arc4random() */ 256 void 257 seed_rng(void) 258 { 259 unsigned char buf[RANDOM_SEED_SIZE]; 260 261 /* Ensure arc4random() is primed */ 262 arc4random_buf(buf, sizeof(buf)); 263 explicit_bzero(buf, sizeof(buf)); 264 } 265 266 #endif /* WITH_OPENSSL */ 267