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 #ifdef WITH_OPENSSL 28 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #ifdef HAVE_SYS_UN_H 32 # include <sys/un.h> 33 #endif 34 35 #include <netinet/in.h> 36 #include <arpa/inet.h> 37 38 #include <errno.h> 39 #include <signal.h> 40 #include <string.h> 41 #include <unistd.h> 42 #include <stddef.h> /* for offsetof */ 43 44 #include <openssl/rand.h> 45 #include <openssl/crypto.h> 46 #include <openssl/err.h> 47 48 #include "openbsd-compat/openssl-compat.h" 49 50 #include "ssh.h" 51 #include "misc.h" 52 #include "xmalloc.h" 53 #include "atomicio.h" 54 #include "pathnames.h" 55 #include "log.h" 56 #include "buffer.h" 57 58 /* 59 * Portable OpenSSH PRNG seeding: 60 * If OpenSSL has not "internally seeded" itself (e.g. pulled data from 61 * /dev/random), then collect RANDOM_SEED_SIZE bytes of randomness from 62 * PRNGd. 63 */ 64 #ifndef OPENSSL_PRNG_ONLY 65 66 #define RANDOM_SEED_SIZE 48 67 68 /* 69 * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon 70 * listening either on 'tcp_port', or via Unix domain socket at * 71 * 'socket_path'. 72 * Either a non-zero tcp_port or a non-null socket_path must be 73 * supplied. 74 * Returns 0 on success, -1 on error 75 */ 76 int 77 get_random_bytes_prngd(unsigned char *buf, int len, 78 unsigned short tcp_port, char *socket_path) 79 { 80 int fd, addr_len, rval, errors; 81 u_char msg[2]; 82 struct sockaddr_storage addr; 83 struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr; 84 struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr; 85 mysig_t old_sigpipe; 86 87 /* Sanity checks */ 88 if (socket_path == NULL && tcp_port == 0) 89 fatal("You must specify a port or a socket"); 90 if (socket_path != NULL && 91 strlen(socket_path) >= sizeof(addr_un->sun_path)) 92 fatal("Random pool path is too long"); 93 if (len <= 0 || len > 255) 94 fatal("Too many bytes (%d) to read from PRNGD", len); 95 96 memset(&addr, '\0', sizeof(addr)); 97 98 if (tcp_port != 0) { 99 addr_in->sin_family = AF_INET; 100 addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK); 101 addr_in->sin_port = htons(tcp_port); 102 addr_len = sizeof(*addr_in); 103 } else { 104 addr_un->sun_family = AF_UNIX; 105 strlcpy(addr_un->sun_path, socket_path, 106 sizeof(addr_un->sun_path)); 107 addr_len = offsetof(struct sockaddr_un, sun_path) + 108 strlen(socket_path) + 1; 109 } 110 111 old_sigpipe = mysignal(SIGPIPE, SIG_IGN); 112 113 errors = 0; 114 rval = -1; 115 reopen: 116 fd = socket(addr.ss_family, SOCK_STREAM, 0); 117 if (fd == -1) { 118 error("Couldn't create socket: %s", strerror(errno)); 119 goto done; 120 } 121 122 if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { 123 if (tcp_port != 0) { 124 error("Couldn't connect to PRNGD port %d: %s", 125 tcp_port, strerror(errno)); 126 } else { 127 error("Couldn't connect to PRNGD socket \"%s\": %s", 128 addr_un->sun_path, strerror(errno)); 129 } 130 goto done; 131 } 132 133 /* Send blocking read request to PRNGD */ 134 msg[0] = 0x02; 135 msg[1] = len; 136 137 if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) { 138 if (errno == EPIPE && errors < 10) { 139 close(fd); 140 errors++; 141 goto reopen; 142 } 143 error("Couldn't write to PRNGD socket: %s", 144 strerror(errno)); 145 goto done; 146 } 147 148 if (atomicio(read, fd, buf, len) != (size_t)len) { 149 if (errno == EPIPE && errors < 10) { 150 close(fd); 151 errors++; 152 goto reopen; 153 } 154 error("Couldn't read from PRNGD socket: %s", 155 strerror(errno)); 156 goto done; 157 } 158 159 rval = 0; 160 done: 161 mysignal(SIGPIPE, old_sigpipe); 162 if (fd != -1) 163 close(fd); 164 return rval; 165 } 166 167 static int 168 seed_from_prngd(unsigned char *buf, size_t bytes) 169 { 170 #ifdef PRNGD_PORT 171 debug("trying egd/prngd port %d", PRNGD_PORT); 172 if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0) 173 return 0; 174 #endif 175 #ifdef PRNGD_SOCKET 176 debug("trying egd/prngd socket %s", PRNGD_SOCKET); 177 if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0) 178 return 0; 179 #endif 180 return -1; 181 } 182 183 void 184 rexec_send_rng_seed(Buffer *m) 185 { 186 u_char buf[RANDOM_SEED_SIZE]; 187 188 if (RAND_bytes(buf, sizeof(buf)) <= 0) { 189 error("Couldn't obtain random bytes (error %ld)", 190 ERR_get_error()); 191 buffer_put_string(m, "", 0); 192 } else 193 buffer_put_string(m, buf, sizeof(buf)); 194 } 195 196 void 197 rexec_recv_rng_seed(Buffer *m) 198 { 199 u_char *buf; 200 u_int len; 201 202 buf = buffer_get_string_ret(m, &len); 203 if (buf != NULL) { 204 debug3("rexec_recv_rng_seed: seeding rng with %u bytes", len); 205 RAND_add(buf, len, len); 206 } 207 } 208 #endif /* OPENSSL_PRNG_ONLY */ 209 210 void 211 seed_rng(void) 212 { 213 #ifndef OPENSSL_PRNG_ONLY 214 unsigned char buf[RANDOM_SEED_SIZE]; 215 #endif 216 if (!ssh_compatible_openssl(OPENSSL_VERSION_NUMBER, SSLeay())) 217 fatal("OpenSSL version mismatch. Built against %lx, you " 218 "have %lx", (u_long)OPENSSL_VERSION_NUMBER, SSLeay()); 219 220 #ifndef OPENSSL_PRNG_ONLY 221 if (RAND_status() == 1) { 222 debug3("RNG is ready, skipping seeding"); 223 return; 224 } 225 226 if (seed_from_prngd(buf, sizeof(buf)) == -1) 227 fatal("Could not obtain seed from PRNGd"); 228 RAND_add(buf, sizeof(buf), sizeof(buf)); 229 memset(buf, '\0', sizeof(buf)); 230 231 #endif /* OPENSSL_PRNG_ONLY */ 232 if (RAND_status() != 1) 233 fatal("PRNG is not seeded"); 234 } 235 236 #else /* WITH_OPENSSL */ 237 238 /* Handled in arc4random() */ 239 void 240 seed_rng(void) 241 { 242 } 243 244 #endif /* WITH_OPENSSL */ 245