| 1 | /* |
| 2 | * Support rsync daemon authentication. |
| 3 | * |
| 4 | * Copyright (C) 1998-2000 Andrew Tridgell |
| 5 | * Copyright (C) 2002, 2004, 2005, 2006 Wayne Davison |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License as published by |
| 9 | * the Free Software Foundation; either version 2 of the License, or |
| 10 | * (at your option) any later version. |
| 11 | * |
| 12 | * This program is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | * GNU General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License along |
| 18 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 19 | * 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. |
| 20 | */ |
| 21 | |
| 22 | #include "rsync.h" |
| 23 | |
| 24 | extern char *password_file; |
| 25 | |
| 26 | /*************************************************************************** |
| 27 | encode a buffer using base64 - simple and slow algorithm. null terminates |
| 28 | the result. |
| 29 | ***************************************************************************/ |
| 30 | void base64_encode(char *buf, int len, char *out, int pad) |
| 31 | { |
| 32 | char *b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
| 33 | int bit_offset, byte_offset, idx, i; |
| 34 | unsigned char *d = (unsigned char *)buf; |
| 35 | int bytes = (len*8 + 5)/6; |
| 36 | |
| 37 | for (i = 0; i < bytes; i++) { |
| 38 | byte_offset = (i*6)/8; |
| 39 | bit_offset = (i*6)%8; |
| 40 | if (bit_offset < 3) { |
| 41 | idx = (d[byte_offset] >> (2-bit_offset)) & 0x3F; |
| 42 | } else { |
| 43 | idx = (d[byte_offset] << (bit_offset-2)) & 0x3F; |
| 44 | if (byte_offset+1 < len) { |
| 45 | idx |= (d[byte_offset+1] >> (8-(bit_offset-2))); |
| 46 | } |
| 47 | } |
| 48 | out[i] = b64[idx]; |
| 49 | } |
| 50 | |
| 51 | while (pad && (i % 4)) |
| 52 | out[i++] = '='; |
| 53 | |
| 54 | out[i] = '\0'; |
| 55 | } |
| 56 | |
| 57 | /* Generate a challenge buffer and return it base64-encoded. */ |
| 58 | static void gen_challenge(char *addr, char *challenge) |
| 59 | { |
| 60 | char input[32]; |
| 61 | char md4_out[MD4_SUM_LENGTH]; |
| 62 | struct timeval tv; |
| 63 | |
| 64 | memset(input, 0, sizeof input); |
| 65 | |
| 66 | strlcpy((char *)input, addr, 17); |
| 67 | sys_gettimeofday(&tv); |
| 68 | SIVAL(input, 16, tv.tv_sec); |
| 69 | SIVAL(input, 20, tv.tv_usec); |
| 70 | SIVAL(input, 24, getpid()); |
| 71 | |
| 72 | sum_init(0); |
| 73 | sum_update(input, sizeof input); |
| 74 | sum_end(md4_out); |
| 75 | |
| 76 | base64_encode(md4_out, MD4_SUM_LENGTH, challenge, 0); |
| 77 | } |
| 78 | |
| 79 | |
| 80 | /* Return the secret for a user from the secret file, null terminated. |
| 81 | * Maximum length is len (not counting the null). */ |
| 82 | static int get_secret(int module, char *user, char *secret, int len) |
| 83 | { |
| 84 | char *fname = lp_secrets_file(module); |
| 85 | STRUCT_STAT st; |
| 86 | int fd, ok = 1; |
| 87 | char ch, *p; |
| 88 | |
| 89 | if (!fname || !*fname) |
| 90 | return 0; |
| 91 | |
| 92 | if ((fd = open(fname, O_RDONLY)) < 0) |
| 93 | return 0; |
| 94 | |
| 95 | if (do_stat(fname, &st) == -1) { |
| 96 | rsyserr(FLOG, errno, "stat(%s)", fname); |
| 97 | ok = 0; |
| 98 | } else if (lp_strict_modes(module)) { |
| 99 | if ((st.st_mode & 06) != 0) { |
| 100 | rprintf(FLOG, "secrets file must not be other-accessible (see strict modes option)\n"); |
| 101 | ok = 0; |
| 102 | } else if (MY_UID() == 0 && st.st_uid != 0) { |
| 103 | rprintf(FLOG, "secrets file must be owned by root when running as root (see strict modes)\n"); |
| 104 | ok = 0; |
| 105 | } |
| 106 | } |
| 107 | if (!ok) { |
| 108 | rprintf(FLOG, "continuing without secrets file\n"); |
| 109 | close(fd); |
| 110 | return 0; |
| 111 | } |
| 112 | |
| 113 | if (*user == '#') { |
| 114 | /* Reject attempt to match a comment. */ |
| 115 | close(fd); |
| 116 | return 0; |
| 117 | } |
| 118 | |
| 119 | /* Try to find a line that starts with the user name and a ':'. */ |
| 120 | p = user; |
| 121 | while (1) { |
| 122 | if (read(fd, &ch, 1) != 1) { |
| 123 | close(fd); |
| 124 | return 0; |
| 125 | } |
| 126 | if (ch == '\n') |
| 127 | p = user; |
| 128 | else if (p) { |
| 129 | if (*p == ch) |
| 130 | p++; |
| 131 | else if (!*p && ch == ':') |
| 132 | break; |
| 133 | else |
| 134 | p = NULL; |
| 135 | } |
| 136 | } |
| 137 | |
| 138 | /* Slurp the secret into the "secret" buffer. */ |
| 139 | p = secret; |
| 140 | while (len > 0) { |
| 141 | if (read(fd, p, 1) != 1 || *p == '\n') |
| 142 | break; |
| 143 | if (*p == '\r') |
| 144 | continue; |
| 145 | p++; |
| 146 | len--; |
| 147 | } |
| 148 | *p = '\0'; |
| 149 | close(fd); |
| 150 | |
| 151 | return 1; |
| 152 | } |
| 153 | |
| 154 | static char *getpassf(char *filename) |
| 155 | { |
| 156 | STRUCT_STAT st; |
| 157 | char buffer[512], *p; |
| 158 | int fd, n, ok = 1; |
| 159 | char *envpw = getenv("RSYNC_PASSWORD"); |
| 160 | |
| 161 | if (!filename) |
| 162 | return NULL; |
| 163 | |
| 164 | if ((fd = open(filename,O_RDONLY)) < 0) { |
| 165 | rsyserr(FERROR, errno, "could not open password file \"%s\"", |
| 166 | filename); |
| 167 | if (envpw) |
| 168 | rprintf(FERROR, "falling back to RSYNC_PASSWORD environment variable.\n"); |
| 169 | return NULL; |
| 170 | } |
| 171 | |
| 172 | if (do_stat(filename, &st) == -1) { |
| 173 | rsyserr(FERROR, errno, "stat(%s)", filename); |
| 174 | ok = 0; |
| 175 | } else if ((st.st_mode & 06) != 0) { |
| 176 | rprintf(FERROR,"password file must not be other-accessible\n"); |
| 177 | ok = 0; |
| 178 | } else if (MY_UID() == 0 && st.st_uid != 0) { |
| 179 | rprintf(FERROR,"password file must be owned by root when running as root\n"); |
| 180 | ok = 0; |
| 181 | } |
| 182 | if (!ok) { |
| 183 | rprintf(FERROR,"continuing without password file\n"); |
| 184 | if (envpw) |
| 185 | rprintf(FERROR, "using RSYNC_PASSWORD environment variable.\n"); |
| 186 | close(fd); |
| 187 | return NULL; |
| 188 | } |
| 189 | |
| 190 | if (envpw) |
| 191 | rprintf(FERROR, "RSYNC_PASSWORD environment variable ignored\n"); |
| 192 | |
| 193 | n = read(fd, buffer, sizeof buffer - 1); |
| 194 | close(fd); |
| 195 | if (n > 0) { |
| 196 | buffer[n] = '\0'; |
| 197 | if ((p = strtok(buffer, "\n\r")) != NULL) |
| 198 | return strdup(p); |
| 199 | } |
| 200 | |
| 201 | return NULL; |
| 202 | } |
| 203 | |
| 204 | /* Generate an MD4 hash created from the combination of the password |
| 205 | * and the challenge string and return it base64-encoded. */ |
| 206 | static void generate_hash(char *in, char *challenge, char *out) |
| 207 | { |
| 208 | char buf[MD4_SUM_LENGTH]; |
| 209 | |
| 210 | sum_init(0); |
| 211 | sum_update(in, strlen(in)); |
| 212 | sum_update(challenge, strlen(challenge)); |
| 213 | sum_end(buf); |
| 214 | |
| 215 | base64_encode(buf, MD4_SUM_LENGTH, out, 0); |
| 216 | } |
| 217 | |
| 218 | /* Possibly negotiate authentication with the client. Use "leader" to |
| 219 | * start off the auth if necessary. |
| 220 | * |
| 221 | * Return NULL if authentication failed. Return "" if anonymous access. |
| 222 | * Otherwise return username. |
| 223 | */ |
| 224 | char *auth_server(int f_in, int f_out, int module, char *host, char *addr, |
| 225 | char *leader) |
| 226 | { |
| 227 | char *users = lp_auth_users(module); |
| 228 | char challenge[MD4_SUM_LENGTH*2]; |
| 229 | char line[BIGPATHBUFLEN]; |
| 230 | char secret[512]; |
| 231 | char pass2[MD4_SUM_LENGTH*2]; |
| 232 | char *tok, *pass; |
| 233 | |
| 234 | /* if no auth list then allow anyone in! */ |
| 235 | if (!users || !*users) |
| 236 | return ""; |
| 237 | |
| 238 | gen_challenge(addr, challenge); |
| 239 | |
| 240 | io_printf(f_out, "%s%s\n", leader, challenge); |
| 241 | |
| 242 | if (!read_line(f_in, line, sizeof line - 1) |
| 243 | || (pass = strchr(line, ' ')) == NULL) { |
| 244 | rprintf(FLOG, "auth failed on module %s from %s (%s): " |
| 245 | "invalid challenge response\n", |
| 246 | lp_name(module), host, addr); |
| 247 | return NULL; |
| 248 | } |
| 249 | *pass++ = '\0'; |
| 250 | |
| 251 | if (!(users = strdup(users))) |
| 252 | out_of_memory("auth_server"); |
| 253 | |
| 254 | for (tok = strtok(users, " ,\t"); tok; tok = strtok(NULL, " ,\t")) { |
| 255 | if (wildmatch(tok, line)) |
| 256 | break; |
| 257 | } |
| 258 | free(users); |
| 259 | |
| 260 | if (!tok) { |
| 261 | rprintf(FLOG, "auth failed on module %s from %s (%s): " |
| 262 | "unauthorized user\n", |
| 263 | lp_name(module), host, addr); |
| 264 | return NULL; |
| 265 | } |
| 266 | |
| 267 | memset(secret, 0, sizeof secret); |
| 268 | if (!get_secret(module, line, secret, sizeof secret - 1)) { |
| 269 | memset(secret, 0, sizeof secret); |
| 270 | rprintf(FLOG, "auth failed on module %s from %s (%s): " |
| 271 | "missing secret for user \"%s\"\n", |
| 272 | lp_name(module), host, addr, line); |
| 273 | return NULL; |
| 274 | } |
| 275 | |
| 276 | generate_hash(secret, challenge, pass2); |
| 277 | memset(secret, 0, sizeof secret); |
| 278 | |
| 279 | if (strcmp(pass, pass2) != 0) { |
| 280 | rprintf(FLOG, "auth failed on module %s from %s (%s): " |
| 281 | "password mismatch\n", |
| 282 | lp_name(module), host, addr); |
| 283 | return NULL; |
| 284 | } |
| 285 | |
| 286 | return strdup(line); |
| 287 | } |
| 288 | |
| 289 | |
| 290 | void auth_client(int fd, char *user, char *challenge) |
| 291 | { |
| 292 | char *pass; |
| 293 | char pass2[MD4_SUM_LENGTH*2]; |
| 294 | |
| 295 | if (!user || !*user) |
| 296 | user = "nobody"; |
| 297 | |
| 298 | if (!(pass = getpassf(password_file)) |
| 299 | && !(pass = getenv("RSYNC_PASSWORD"))) { |
| 300 | /* XXX: cyeoh says that getpass is deprecated, because |
| 301 | * it may return a truncated password on some systems, |
| 302 | * and it is not in the LSB. |
| 303 | * |
| 304 | * Andrew Klein says that getpassphrase() is present |
| 305 | * on Solaris and reads up to 256 characters. |
| 306 | * |
| 307 | * OpenBSD has a readpassphrase() that might be more suitable. |
| 308 | */ |
| 309 | pass = getpass("Password: "); |
| 310 | } |
| 311 | |
| 312 | if (!pass) |
| 313 | pass = ""; |
| 314 | |
| 315 | generate_hash(pass, challenge, pass2); |
| 316 | io_printf(fd, "%s %s\n", user, pass2); |
| 317 | } |