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 <sys/types.h> 28 #include <sys/socket.h> 29 #ifdef HAVE_SYS_UN_H 30 # include <sys/un.h> 31 #endif 32 33 #include <netinet/in.h> 34 #include <arpa/inet.h> 35 36 #include <errno.h> 37 #include <signal.h> 38 #include <string.h> 39 #include <unistd.h> 40 #include <stddef.h> /* for offsetof */ 41 42 #include <openssl/rand.h> 43 #include <openssl/crypto.h> 44 #include <openssl/err.h> 45 46 #include "ssh.h" 47 #include "misc.h" 48 #include "xmalloc.h" 49 #include "atomicio.h" 50 #include "pathnames.h" 51 #include "log.h" 52 #include "buffer.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 #define RANDOM_SEED_SIZE 48 63 64 /* 65 * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon 66 * listening either on 'tcp_port', or via Unix domain socket at * 67 * 'socket_path'. 68 * Either a non-zero tcp_port or a non-null socket_path must be 69 * supplied. 70 * Returns 0 on success, -1 on error 71 */ 72 int 73 get_random_bytes_prngd(unsigned char *buf, int len, 74 unsigned short tcp_port, char *socket_path) 75 { 76 int fd, addr_len, rval, errors; 77 u_char msg[2]; 78 struct sockaddr_storage addr; 79 struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr; 80 struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr; 81 mysig_t old_sigpipe; 82 83 /* Sanity checks */ 84 if (socket_path == NULL && tcp_port == 0) 85 fatal("You must specify a port or a socket"); 86 if (socket_path != NULL && 87 strlen(socket_path) >= sizeof(addr_un->sun_path)) 88 fatal("Random pool path is too long"); 89 if (len <= 0 || len > 255) 90 fatal("Too many bytes (%d) to read from PRNGD", len); 91 92 memset(&addr, '\0', sizeof(addr)); 93 94 if (tcp_port != 0) { 95 addr_in->sin_family = AF_INET; 96 addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK); 97 addr_in->sin_port = htons(tcp_port); 98 addr_len = sizeof(*addr_in); 99 } else { 100 addr_un->sun_family = AF_UNIX; 101 strlcpy(addr_un->sun_path, socket_path, 102 sizeof(addr_un->sun_path)); 103 addr_len = offsetof(struct sockaddr_un, sun_path) + 104 strlen(socket_path) + 1; 105 } 106 107 old_sigpipe = mysignal(SIGPIPE, SIG_IGN); 108 109 errors = 0; 110 rval = -1; 111 reopen: 112 fd = socket(addr.ss_family, SOCK_STREAM, 0); 113 if (fd == -1) { 114 error("Couldn't create socket: %s", strerror(errno)); 115 goto done; 116 } 117 118 if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { 119 if (tcp_port != 0) { 120 error("Couldn't connect to PRNGD port %d: %s", 121 tcp_port, strerror(errno)); 122 } else { 123 error("Couldn't connect to PRNGD socket \"%s\": %s", 124 addr_un->sun_path, strerror(errno)); 125 } 126 goto done; 127 } 128 129 /* Send blocking read request to PRNGD */ 130 msg[0] = 0x02; 131 msg[1] = len; 132 133 if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) { 134 if (errno == EPIPE && errors < 10) { 135 close(fd); 136 errors++; 137 goto reopen; 138 } 139 error("Couldn't write to PRNGD socket: %s", 140 strerror(errno)); 141 goto done; 142 } 143 144 if (atomicio(read, fd, buf, len) != (size_t)len) { 145 if (errno == EPIPE && errors < 10) { 146 close(fd); 147 errors++; 148 goto reopen; 149 } 150 error("Couldn't read from PRNGD socket: %s", 151 strerror(errno)); 152 goto done; 153 } 154 155 rval = 0; 156 done: 157 mysignal(SIGPIPE, old_sigpipe); 158 if (fd != -1) 159 close(fd); 160 return rval; 161 } 162 163 static int 164 seed_from_prngd(unsigned char *buf, size_t bytes) 165 { 166 #ifdef PRNGD_PORT 167 debug("trying egd/prngd port %d", PRNGD_PORT); 168 if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0) 169 return 0; 170 #endif 171 #ifdef PRNGD_SOCKET 172 debug("trying egd/prngd socket %s", PRNGD_SOCKET); 173 if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0) 174 return 0; 175 #endif 176 return -1; 177 } 178 179 void 180 rexec_send_rng_seed(Buffer *m) 181 { 182 u_char buf[RANDOM_SEED_SIZE]; 183 184 if (RAND_bytes(buf, sizeof(buf)) <= 0) { 185 error("Couldn't obtain random bytes (error %ld)", 186 ERR_get_error()); 187 buffer_put_string(m, "", 0); 188 } else 189 buffer_put_string(m, buf, sizeof(buf)); 190 } 191 192 void 193 rexec_recv_rng_seed(Buffer *m) 194 { 195 u_char *buf; 196 u_int len; 197 198 buf = buffer_get_string_ret(m, &len); 199 if (buf != NULL) { 200 debug3("rexec_recv_rng_seed: seeding rng with %u bytes", len); 201 RAND_add(buf, len, len); 202 } 203 } 204 #endif /* OPENSSL_PRNG_ONLY */ 205 206 void 207 seed_rng(void) 208 { 209 #ifndef OPENSSL_PRNG_ONLY 210 unsigned char buf[RANDOM_SEED_SIZE]; 211 #endif 212 /* 213 * OpenSSL version numbers: MNNFFPPS: major minor fix patch status 214 * We match major, minor, fix and status (not patch) 215 */ 216 if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L) 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
