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