| 1 | /* -*- c-file-style: "linux"; -*- |
| 2 | |
| 3 | Copyright (C) 1998-2000 by Andrew Tridgell |
| 4 | |
| 5 | This program is free software; you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by |
| 7 | the Free Software Foundation; either version 2 of the License, or |
| 8 | (at your option) any later version. |
| 9 | |
| 10 | This program is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | GNU General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU General Public License |
| 16 | along with this program; if not, write to the Free Software |
| 17 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| 18 | */ |
| 19 | |
| 20 | /* support rsync authentication */ |
| 21 | #include "rsync.h" |
| 22 | |
| 23 | extern char *password_file; |
| 24 | |
| 25 | /*************************************************************************** |
| 26 | encode a buffer using base64 - simple and slow algorithm. null terminates |
| 27 | the result. |
| 28 | ***************************************************************************/ |
| 29 | void base64_encode(char *buf, int len, char *out, int pad) |
| 30 | { |
| 31 | char *b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
| 32 | int bit_offset, byte_offset, idx, i; |
| 33 | unsigned char *d = (unsigned char *)buf; |
| 34 | int bytes = (len*8 + 5)/6; |
| 35 | |
| 36 | for (i = 0; i < bytes; i++) { |
| 37 | byte_offset = (i*6)/8; |
| 38 | bit_offset = (i*6)%8; |
| 39 | if (bit_offset < 3) { |
| 40 | idx = (d[byte_offset] >> (2-bit_offset)) & 0x3F; |
| 41 | } else { |
| 42 | idx = (d[byte_offset] << (bit_offset-2)) & 0x3F; |
| 43 | if (byte_offset+1 < len) { |
| 44 | idx |= (d[byte_offset+1] >> (8-(bit_offset-2))); |
| 45 | } |
| 46 | } |
| 47 | out[i] = b64[idx]; |
| 48 | } |
| 49 | |
| 50 | while (pad && (i % 4)) |
| 51 | out[i++] = '='; |
| 52 | |
| 53 | out[i] = '\0'; |
| 54 | } |
| 55 | |
| 56 | /* Generate a challenge buffer and return it base64-encoded. */ |
| 57 | static void gen_challenge(char *addr, char *challenge) |
| 58 | { |
| 59 | char input[32]; |
| 60 | char md4_out[MD4_SUM_LENGTH]; |
| 61 | struct timeval tv; |
| 62 | |
| 63 | memset(input, 0, sizeof input); |
| 64 | |
| 65 | strlcpy((char *)input, addr, 17); |
| 66 | sys_gettimeofday(&tv); |
| 67 | SIVAL(input, 16, tv.tv_sec); |
| 68 | SIVAL(input, 20, tv.tv_usec); |
| 69 | SIVAL(input, 24, getpid()); |
| 70 | |
| 71 | sum_init(0); |
| 72 | sum_update(input, sizeof input); |
| 73 | sum_end(md4_out); |
| 74 | |
| 75 | base64_encode(md4_out, MD4_SUM_LENGTH, challenge, 0); |
| 76 | } |
| 77 | |
| 78 | |
| 79 | /* Return the secret for a user from the secret file, null terminated. |
| 80 | * Maximum length is len (not counting the null). */ |
| 81 | static int get_secret(int module, char *user, char *secret, int len) |
| 82 | { |
| 83 | char *fname = lp_secrets_file(module); |
| 84 | STRUCT_STAT st; |
| 85 | int fd, ok = 1; |
| 86 | char ch, *p; |
| 87 | |
| 88 | if (!fname || !*fname) |
| 89 | return 0; |
| 90 | |
| 91 | if ((fd = open(fname, O_RDONLY)) < 0) |
| 92 | return 0; |
| 93 | |
| 94 | if (do_stat(fname, &st) == -1) { |
| 95 | rsyserr(FLOG, errno, "stat(%s)", fname); |
| 96 | ok = 0; |
| 97 | } else if (lp_strict_modes(module)) { |
| 98 | if ((st.st_mode & 06) != 0) { |
| 99 | rprintf(FLOG, "secrets file must not be other-accessible (see strict modes option)\n"); |
| 100 | ok = 0; |
| 101 | } else if (MY_UID() == 0 && st.st_uid != 0) { |
| 102 | rprintf(FLOG, "secrets file must be owned by root when running as root (see strict modes)\n"); |
| 103 | ok = 0; |
| 104 | } |
| 105 | } |
| 106 | if (!ok) { |
| 107 | rprintf(FLOG, "continuing without secrets file\n"); |
| 108 | close(fd); |
| 109 | return 0; |
| 110 | } |
| 111 | |
| 112 | if (*user == '#') { |
| 113 | /* Reject attempt to match a comment. */ |
| 114 | close(fd); |
| 115 | return 0; |
| 116 | } |
| 117 | |
| 118 | /* Try to find a line that starts with the user name and a ':'. */ |
| 119 | p = user; |
| 120 | while (1) { |
| 121 | if (read(fd, &ch, 1) != 1) { |
| 122 | close(fd); |
| 123 | return 0; |
| 124 | } |
| 125 | if (ch == '\n') |
| 126 | p = user; |
| 127 | else if (p) { |
| 128 | if (*p == ch) |
| 129 | p++; |
| 130 | else if (!*p && ch == ':') |
| 131 | break; |
| 132 | else |
| 133 | p = NULL; |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | /* Slurp the secret into the "secret" buffer. */ |
| 138 | p = secret; |
| 139 | while (len > 0) { |
| 140 | if (read(fd, p, 1) != 1 || *p == '\n') |
| 141 | break; |
| 142 | if (*p == '\r') |
| 143 | continue; |
| 144 | p++; |
| 145 | len--; |
| 146 | } |
| 147 | *p = '\0'; |
| 148 | close(fd); |
| 149 | |
| 150 | return 1; |
| 151 | } |
| 152 | |
| 153 | static char *getpassf(char *filename) |
| 154 | { |
| 155 | STRUCT_STAT st; |
| 156 | char buffer[512], *p; |
| 157 | int fd, n, ok = 1; |
| 158 | char *envpw = getenv("RSYNC_PASSWORD"); |
| 159 | |
| 160 | if (!filename) |
| 161 | return NULL; |
| 162 | |
| 163 | if ((fd = open(filename,O_RDONLY)) < 0) { |
| 164 | rsyserr(FERROR, errno, "could not open password file \"%s\"", |
| 165 | filename); |
| 166 | if (envpw) |
| 167 | rprintf(FERROR, "falling back to RSYNC_PASSWORD environment variable.\n"); |
| 168 | return NULL; |
| 169 | } |
| 170 | |
| 171 | if (do_stat(filename, &st) == -1) { |
| 172 | rsyserr(FERROR, errno, "stat(%s)", filename); |
| 173 | ok = 0; |
| 174 | } else if ((st.st_mode & 06) != 0) { |
| 175 | rprintf(FERROR,"password file must not be other-accessible\n"); |
| 176 | ok = 0; |
| 177 | } else if (MY_UID() == 0 && st.st_uid != 0) { |
| 178 | rprintf(FERROR,"password file must be owned by root when running as root\n"); |
| 179 | ok = 0; |
| 180 | } |
| 181 | if (!ok) { |
| 182 | rprintf(FERROR,"continuing without password file\n"); |
| 183 | if (envpw) |
| 184 | rprintf(FERROR, "using RSYNC_PASSWORD environment variable.\n"); |
| 185 | close(fd); |
| 186 | return NULL; |
| 187 | } |
| 188 | |
| 189 | if (envpw) |
| 190 | rprintf(FERROR, "RSYNC_PASSWORD environment variable ignored\n"); |
| 191 | |
| 192 | n = read(fd, buffer, sizeof buffer - 1); |
| 193 | close(fd); |
| 194 | if (n > 0) { |
| 195 | buffer[n] = '\0'; |
| 196 | if ((p = strtok(buffer, "\n\r")) != NULL) |
| 197 | return strdup(p); |
| 198 | } |
| 199 | |
| 200 | return NULL; |
| 201 | } |
| 202 | |
| 203 | /* Generate an MD4 hash created from the combination of the password |
| 204 | * and the challenge string and return it base64-encoded. */ |
| 205 | static void generate_hash(char *in, char *challenge, char *out) |
| 206 | { |
| 207 | char buf[MD4_SUM_LENGTH]; |
| 208 | |
| 209 | sum_init(0); |
| 210 | sum_update(in, strlen(in)); |
| 211 | sum_update(challenge, strlen(challenge)); |
| 212 | sum_end(buf); |
| 213 | |
| 214 | base64_encode(buf, MD4_SUM_LENGTH, out, 0); |
| 215 | } |
| 216 | |
| 217 | /* Possibly negotiate authentication with the client. Use "leader" to |
| 218 | * start off the auth if necessary. |
| 219 | * |
| 220 | * Return NULL if authentication failed. Return "" if anonymous access. |
| 221 | * Otherwise return username. |
| 222 | */ |
| 223 | char *auth_server(int f_in, int f_out, int module, char *host, char *addr, |
| 224 | char *leader) |
| 225 | { |
| 226 | char *users = lp_auth_users(module); |
| 227 | char challenge[MD4_SUM_LENGTH*2]; |
| 228 | char line[BIGPATHBUFLEN]; |
| 229 | char secret[512]; |
| 230 | char pass2[MD4_SUM_LENGTH*2]; |
| 231 | char *tok, *pass; |
| 232 | |
| 233 | /* if no auth list then allow anyone in! */ |
| 234 | if (!users || !*users) |
| 235 | return ""; |
| 236 | |
| 237 | gen_challenge(addr, challenge); |
| 238 | |
| 239 | io_printf(f_out, "%s%s\n", leader, challenge); |
| 240 | |
| 241 | if (!read_line(f_in, line, sizeof line - 1) |
| 242 | || (pass = strchr(line, ' ')) == NULL) { |
| 243 | rprintf(FLOG, "auth failed on module %s from %s (%s): " |
| 244 | "invalid challenge response\n", |
| 245 | lp_name(module), host, addr); |
| 246 | return NULL; |
| 247 | } |
| 248 | *pass++ = '\0'; |
| 249 | |
| 250 | if (!(users = strdup(users))) |
| 251 | out_of_memory("auth_server"); |
| 252 | |
| 253 | for (tok = strtok(users, " ,\t"); tok; tok = strtok(NULL, " ,\t")) { |
| 254 | if (wildmatch(tok, line)) |
| 255 | break; |
| 256 | } |
| 257 | free(users); |
| 258 | |
| 259 | if (!tok) { |
| 260 | rprintf(FLOG, "auth failed on module %s from %s (%s): " |
| 261 | "unauthorized user\n", |
| 262 | lp_name(module), host, addr); |
| 263 | return NULL; |
| 264 | } |
| 265 | |
| 266 | memset(secret, 0, sizeof secret); |
| 267 | if (!get_secret(module, line, secret, sizeof secret - 1)) { |
| 268 | memset(secret, 0, sizeof secret); |
| 269 | rprintf(FLOG, "auth failed on module %s from %s (%s): " |
| 270 | "missing secret for user \"%s\"\n", |
| 271 | lp_name(module), host, addr, line); |
| 272 | return NULL; |
| 273 | } |
| 274 | |
| 275 | generate_hash(secret, challenge, pass2); |
| 276 | memset(secret, 0, sizeof secret); |
| 277 | |
| 278 | if (strcmp(pass, pass2) != 0) { |
| 279 | rprintf(FLOG, "auth failed on module %s from %s (%s): " |
| 280 | "password mismatch\n", |
| 281 | lp_name(module), host, addr); |
| 282 | return NULL; |
| 283 | } |
| 284 | |
| 285 | return strdup(line); |
| 286 | } |
| 287 | |
| 288 | |
| 289 | void auth_client(int fd, char *user, char *challenge) |
| 290 | { |
| 291 | char *pass; |
| 292 | char pass2[MD4_SUM_LENGTH*2]; |
| 293 | |
| 294 | if (!user || !*user) |
| 295 | user = "nobody"; |
| 296 | |
| 297 | if (!(pass = getpassf(password_file)) |
| 298 | && !(pass = getenv("RSYNC_PASSWORD"))) { |
| 299 | /* XXX: cyeoh says that getpass is deprecated, because |
| 300 | * it may return a truncated password on some systems, |
| 301 | * and it is not in the LSB. |
| 302 | * |
| 303 | * Andrew Klein says that getpassphrase() is present |
| 304 | * on Solaris and reads up to 256 characters. |
| 305 | * |
| 306 | * OpenBSD has a readpassphrase() that might be more suitable. |
| 307 | */ |
| 308 | pass = getpass("Password: "); |
| 309 | } |
| 310 | |
| 311 | if (!pass) |
| 312 | pass = ""; |
| 313 | |
| 314 | generate_hash(pass, challenge, pass2); |
| 315 | io_printf(fd, "%s %s\n", user, pass2); |
| 316 | } |