source3/web/cgi.c

   1 /*
   2    some simple CGI helper routines
   3    Copyright (C) Andrew Tridgell 1997-1998
   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 3 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, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19
  20 #include "includes.h"
  21 #include "web/swat_proto.h"
  22 #include "secrets.h"
  23 #include "../lib/util/util.h"
  24
  25 #define MAX_VARIABLES 10000
  26
  27 /* set the expiry on fixed pages */
  28 #define EXPIRY_TIME (60*60*24*7)
  29
  30 #ifdef DEBUG_COMMENTS
  31 extern void print_title(char *fmt, ...);
  32 #endif
  33
  34 struct cgi_var {
  35         char *name;
  36         char *value;
  37 };
  38
  39 static struct cgi_var variables[MAX_VARIABLES];
  40 static int num_variables;
  41 static int content_length;
  42 static int request_post;
  43 static char *query_string;
  44 static const char *baseurl;
  45 static char *pathinfo;
  46 static char *C_user;
  47 static char *C_pass;
  48 static char *C_nonce;
  49 static bool inetd_server;
  50 static bool got_request;
  51
  52 static char *grab_line(FILE *f, int *cl)
  53 {
  54         char *ret = NULL;
  55         int i = 0;
  56         int len = 0;
  57
  58         while ((*cl)) {
  59                 int c;
  60
  61                 if (i == len) {
  62                         char *ret2;
  63                         if (len == 0) len = 1024;
  64                         else len *= 2;
  65                         ret2 = (char *)SMB_REALLOC_KEEP_OLD_ON_ERROR(ret, len);
  66                         if (!ret2) return ret;
  67                         ret = ret2;
  68                 }
  69
  70                 c = fgetc(f);
  71                 (*cl)--;
  72
  73                 if (c == EOF) {
  74                         (*cl) = 0;
  75                         break;
  76                 }
  77
  78                 if (c == '\r') continue;
  79
  80                 if (strchr_m("\n&", c)) break;
  81
  82                 ret[i++] = c;
  83
  84         }
  85
  86         if (ret) {
  87                 ret[i] = 0;
  88         }
  89         return ret;
  90 }
  91
  92 /**
  93  URL encoded strings can have a '+', which should be replaced with a space
  94
  95  (This was in rfc1738_unescape(), but that broke the squid helper)
  96 **/
  97
  98 static void plus_to_space_unescape(char *buf)
  99 {
 100         char *p=buf;
 101
 102         while ((p=strchr_m(p,'+')))
 103                 *p = ' ';
 104 }
 105
 106 /***************************************************************************
 107   load all the variables passed to the CGI program. May have multiple variables
 108   with the same name and the same or different values. Takes a file parameter
 109   for simulating CGI invocation eg loading saved preferences.
 110   ***************************************************************************/
 111 void cgi_load_variables(void)
 112 {
 113         static char *line;
 114         char *p, *s, *tok;
 115         int len, i;
 116         FILE *f = stdin;
 117
 118 #ifdef DEBUG_COMMENTS
 119         char dummy[100]="";
 120         print_title(dummy);
 121         d_printf("<!== Start dump in cgi_load_variables() %s ==>\n",__FILE__);
 122 #endif
 123
 124         if (!content_length) {
 125                 p = getenv("CONTENT_LENGTH");
 126                 len = p?atoi(p):0;
 127         } else {
 128                 len = content_length;
 129         }
 130
 131
 132         if (len > 0 &&
 133             (request_post ||
 134              ((s=getenv("REQUEST_METHOD")) &&
 135               strequal(s,"POST")))) {
 136                 while (len && (line=grab_line(f, &len))) {
 137                         p = strchr_m(line,'=');
 138                         if (!p) continue;
 139
 140                         *p = 0;
 141
 142                         variables[num_variables].name = SMB_STRDUP(line);
 143                         variables[num_variables].value = SMB_STRDUP(p+1);
 144
 145                         SAFE_FREE(line);
 146
 147                         if (!variables[num_variables].name ||
 148                             !variables[num_variables].value)
 149                                 continue;
 150
 151                         plus_to_space_unescape(variables[num_variables].value);
 152                         rfc1738_unescape(variables[num_variables].value);
 153                         plus_to_space_unescape(variables[num_variables].name);
 154                         rfc1738_unescape(variables[num_variables].name);
 155
 156 #ifdef DEBUG_COMMENTS
 157                         printf("<!== POST var %s has value \"%s\"  ==>\n",
 158                                variables[num_variables].name,
 159                                variables[num_variables].value);
 160 #endif
 161
 162                         num_variables++;
 163                         if (num_variables == MAX_VARIABLES) break;
 164                 }
 165         }
 166
 167         fclose(stdin);
 168         open("/dev/null", O_RDWR);
 169
 170         if ((s=query_string) || (s=getenv("QUERY_STRING"))) {
 171                 char *saveptr;
 172                 for (tok=strtok_r(s, "&;", &saveptr); tok;
 173                      tok=strtok_r(NULL, "&;", &saveptr)) {
 174                         p = strchr_m(tok,'=');
 175                         if (!p) continue;
 176
 177                         *p = 0;
 178
 179                         variables[num_variables].name = SMB_STRDUP(tok);
 180                         variables[num_variables].value = SMB_STRDUP(p+1);
 181
 182                         if (!variables[num_variables].name ||
 183                             !variables[num_variables].value)
 184                                 continue;
 185
 186                         plus_to_space_unescape(variables[num_variables].value);
 187                         rfc1738_unescape(variables[num_variables].value);
 188                         plus_to_space_unescape(variables[num_variables].name);
 189                         rfc1738_unescape(variables[num_variables].name);
 190
 191 #ifdef DEBUG_COMMENTS
 192                         printf("<!== Commandline var %s has value \"%s\"  ==>\n",
 193                                variables[num_variables].name,
 194                                variables[num_variables].value);
 195 #endif
 196                         num_variables++;
 197                         if (num_variables == MAX_VARIABLES) break;
 198                 }
 199
 200         }
 201 #ifdef DEBUG_COMMENTS
 202         printf("<!== End dump in cgi_load_variables() ==>\n");
 203 #endif
 204
 205         /* variables from the client are in UTF-8 - convert them
 206            to our internal unix charset before use */
 207         for (i=0;i<num_variables;i++) {
 208                 TALLOC_CTX *frame = talloc_stackframe();
 209                 char *dest = NULL;
 210                 size_t dest_len;
 211
 212                 convert_string_talloc(frame, CH_UTF8, CH_UNIX,
 213                                variables[i].name, strlen(variables[i].name),
 214                                &dest, &dest_len, True);
 215                 SAFE_FREE(variables[i].name);
 216                 variables[i].name = SMB_STRDUP(dest ? dest : "");
 217
 218                 dest = NULL;
 219                 convert_string_talloc(frame, CH_UTF8, CH_UNIX,
 220                                variables[i].value, strlen(variables[i].value),
 221                                &dest, &dest_len, True);
 222                 SAFE_FREE(variables[i].value);
 223                 variables[i].value = SMB_STRDUP(dest ? dest : "");
 224                 TALLOC_FREE(frame);
 225         }
 226 }
 227
 228
 229 /***************************************************************************
 230   find a variable passed via CGI
 231   Doesn't quite do what you think in the case of POST text variables, because
 232   if they exist they might have a value of "" or even " ", depending on the
 233   browser. Also doesn't allow for variables[] containing multiple variables
 234   with the same name and the same or different values.
 235   ***************************************************************************/
 236
 237 const char *cgi_variable(const char *name)
 238 {
 239         int i;
 240
 241         for (i=0;i<num_variables;i++)
 242                 if (strcmp(variables[i].name, name) == 0)
 243                         return variables[i].value;
 244         return NULL;
 245 }
 246
 247 /***************************************************************************
 248  Version of the above that can't return a NULL pointer.
 249 ***************************************************************************/
 250
 251 const char *cgi_variable_nonull(const char *name)
 252 {
 253         const char *var = cgi_variable(name);
 254         if (var) {
 255                 return var;
 256         } else {
 257                 return "";
 258         }
 259 }
 260
 261 /***************************************************************************
 262 tell a browser about a fatal error in the http processing
 263   ***************************************************************************/
 264 static void cgi_setup_error(const char *err, const char *header, const char *info)
 265 {
 266         if (!got_request) {
 267                 /* damn browsers don't like getting cut off before they give a request */
 268                 char line[1024];
 269                 while (fgets(line, sizeof(line)-1, stdin)) {
 270                         if (strnequal(line,"GET ", 4) ||
 271                             strnequal(line,"POST ", 5) ||
 272                             strnequal(line,"PUT ", 4)) {
 273                                 break;
 274                         }
 275                 }
 276         }
 277
 278         d_printf("HTTP/1.0 %s\r\n%sConnection: close\r\nContent-Type: text/html\r\n\r\n<HTML><HEAD><TITLE>%s</TITLE></HEAD><BODY><H1>%s</H1>%s<p></BODY></HTML>\r\n\r\n", err, header, err, err, info);
 279         fclose(stdin);
 280         fclose(stdout);
 281         exit(0);
 282 }
 283
 284
 285 /***************************************************************************
 286 tell a browser about a fatal authentication error
 287   ***************************************************************************/
 288 static void cgi_auth_error(void)
 289 {
 290         if (inetd_server) {
 291                 cgi_setup_error("401 Authorization Required",
 292                                 "WWW-Authenticate: Basic realm=\"SWAT\"\r\n",
 293                                 "You must be authenticated to use this service");
 294         } else {
 295                 printf("Content-Type: text/html\r\n");
 296
 297                 printf("\r\n<HTML><HEAD><TITLE>SWAT</TITLE></HEAD>\n");
 298                 printf("<BODY><H1>Installation Error</H1>\n");
 299                 printf("SWAT must be installed via inetd. It cannot be run as a CGI script<p>\n");
 300                 printf("</BODY></HTML>\r\n");
 301         }
 302         exit(0);
 303 }
 304
 305 /***************************************************************************
 306 authenticate when we are running as a CGI
 307   ***************************************************************************/
 308 static void cgi_web_auth(void)
 309 {
 310         const char *user = getenv("REMOTE_USER");
 311         struct passwd *pwd;
 312         const char *head = "Content-Type: text/html\r\n\r\n<HTML><BODY><H1>SWAT installation Error</H1>\n";
 313         const char *tail = "</BODY></HTML>\r\n";
 314
 315         if (!user) {
 316                 printf("%sREMOTE_USER not set. Not authenticated by web server.<br>%s\n",
 317                        head, tail);
 318                 exit(0);
 319         }
 320
 321         pwd = Get_Pwnam_alloc(talloc_autofree_context(), user);
 322         if (!pwd) {
 323                 printf("%sCannot find user %s<br>%s\n", head, user, tail);
 324                 exit(0);
 325         }
 326
 327         C_user = SMB_STRDUP(user);
 328
 329         if (!setuid(0)) {
 330                 C_pass = SMB_STRDUP(cgi_nonce());
 331         }
 332         setuid(pwd->pw_uid);
 333         if (geteuid() != pwd->pw_uid || getuid() != pwd->pw_uid) {
 334                 printf("%sFailed to become user %s - uid=%d/%d<br>%s\n",
 335                        head, user, (int)geteuid(), (int)getuid(), tail);
 336                 exit(0);
 337         }
 338         TALLOC_FREE(pwd);
 339 }
 340
 341
 342 /***************************************************************************
 343 handle a http authentication line
 344   ***************************************************************************/
 345 static bool cgi_handle_authorization(char *line)
 346 {
 347         char *p;
 348         fstring user, user_pass;
 349         struct passwd *pass = NULL;
 350
 351         if (!strnequal(line,"Basic ", 6)) {
 352                 goto err;
 353         }
 354         line += 6;
 355         while (line[0] == ' ') line++;
 356         base64_decode_inplace(line);
 357         if (!(p=strchr_m(line,':'))) {
 358                 /*
 359                  * Always give the same error so a cracker
 360                  * cannot tell why we fail.
 361                  */
 362                 goto err;
 363         }
 364         *p = 0;
 365
 366         convert_string(CH_UTF8, CH_UNIX,
 367                        line, -1,
 368                        user, sizeof(user), True);
 369
 370         convert_string(CH_UTF8, CH_UNIX,
 371                        p+1, -1,
 372                        user_pass, sizeof(user_pass), True);
 373
 374         /*
 375          * Try and get the user from the UNIX password file.
 376          */
 377
 378         pass = Get_Pwnam_alloc(talloc_autofree_context(), user);
 379
 380         /*
 381          * Validate the password they have given.
 382          */
 383
 384         if NT_STATUS_IS_OK(pass_check(pass, user, user_pass,
 385                       strlen(user_pass), NULL, False)) {
 386
 387                 if (pass) {
 388                         /*
 389                          * Password was ok.
 390                          */
 391
 392                         if ( initgroups(pass->pw_name, pass->pw_gid) != 0 )
 393                                 goto err;
 394
 395                         become_user_permanently(pass->pw_uid, pass->pw_gid);
 396
 397                         /* Save the users name */
 398                         C_user = SMB_STRDUP(user);
 399                         C_pass = SMB_STRDUP(user_pass);
 400                         TALLOC_FREE(pass);
 401                         return True;
 402                 }
 403         }
 404
 405 err:
 406         cgi_setup_error("401 Bad Authorization",
 407                         "WWW-Authenticate: Basic realm=\"SWAT\"\r\n",
 408                         "username or password incorrect");
 409
 410         TALLOC_FREE(pass);
 411         return False;
 412 }
 413
 414 /***************************************************************************
 415 is this root?
 416   ***************************************************************************/
 417 bool am_root(void)
 418 {
 419         if (geteuid() == 0) {
 420                 return( True);
 421         } else {
 422                 return( False);
 423         }
 424 }
 425
 426 /***************************************************************************
 427 return a ptr to the users name
 428   ***************************************************************************/
 429 char *cgi_user_name(void)
 430 {
 431         return(C_user);
 432 }
 433
 434 /***************************************************************************
 435 return a ptr to the users password
 436   ***************************************************************************/
 437 char *cgi_user_pass(void)
 438 {
 439         return(C_pass);
 440 }
 441
 442 /***************************************************************************
 443 return a ptr to the nonce
 444   ***************************************************************************/
 445 char *cgi_nonce(void)
 446 {
 447         const char *head = "Content-Type: text/html\r\n\r\n<HTML><BODY><H1>SWAT installation Error</H1>\n";
 448         const char *tail = "</BODY></HTML>\r\n";
 449         C_nonce = secrets_fetch_generic("root", "SWAT");
 450         if (C_nonce == NULL) {
 451                 char *tmp_pass = NULL;
 452                 tmp_pass = generate_random_str(talloc_tos(), 16);
 453                 if (tmp_pass == NULL) {
 454                         printf("%sFailed to create random nonce for "
 455                                "SWAT session\n<br>%s\n", head, tail);
 456                         exit(0);
 457                 }
 458                 secrets_store_generic("root", "SWAT", tmp_pass);
 459                 C_nonce = SMB_STRDUP(tmp_pass);
 460                 TALLOC_FREE(tmp_pass);
 461         }
 462         return(C_nonce);
 463 }
 464
 465
 466 /***************************************************************************
 467 handle a file download
 468   ***************************************************************************/
 469 static void cgi_download(char *file)
 470 {
 471         SMB_STRUCT_STAT st;
 472         char buf[1024];
 473         int fd, l, i;
 474         char *p;
 475         char *lang;
 476
 477         /* sanitise the filename */
 478         for (i=0;file[i];i++) {
 479                 if (!isalnum((int)file[i]) && !strchr_m("/.-_", file[i])) {
 480                         cgi_setup_error("404 File Not Found","",
 481                                         "Illegal character in filename");
 482                 }
 483         }
 484
 485         if (sys_stat(file, &st, false) != 0)    {
 486                 cgi_setup_error("404 File Not Found","",
 487                                 "The requested file was not found");
 488         }
 489
 490         if (S_ISDIR(st.st_ex_mode))
 491         {
 492                 snprintf(buf, sizeof(buf), "%s/index.html", file);
 493                 if (!file_exist_stat(buf, &st, false)
 494                     || !S_ISREG(st.st_ex_mode))
 495                 {
 496                         cgi_setup_error("404 File Not Found","",
 497                                         "The requested file was not found");
 498                 }
 499         }
 500         else if (S_ISREG(st.st_ex_mode))
 501         {
 502                 snprintf(buf, sizeof(buf), "%s", file);
 503         }
 504         else
 505         {
 506                 cgi_setup_error("404 File Not Found","",
 507                                 "The requested file was not found");
 508         }
 509
 510         fd = web_open(buf,O_RDONLY,0);
 511         if (fd == -1) {
 512                 cgi_setup_error("404 File Not Found","",
 513                                 "The requested file was not found");
 514         }
 515         printf("HTTP/1.0 200 OK\r\n");
 516         if ((p=strrchr_m(buf, '.'))) {
 517                 if (strcmp(p,".gif")==0) {
 518                         printf("Content-Type: image/gif\r\n");
 519                 } else if (strcmp(p,".jpg")==0) {
 520                         printf("Content-Type: image/jpeg\r\n");
 521                 } else if (strcmp(p,".png")==0) {
 522                         printf("Content-Type: image/png\r\n");
 523                 } else if (strcmp(p,".css")==0) {
 524                         printf("Content-Type: text/css\r\n");
 525                 } else if (strcmp(p,".txt")==0) {
 526                         printf("Content-Type: text/plain\r\n");
 527                 } else {
 528                         printf("Content-Type: text/html\r\n");
 529                 }
 530         }
 531         printf("Expires: %s\r\n",
 532                    http_timestring(talloc_tos(), time(NULL)+EXPIRY_TIME));
 533
 534         lang = lang_tdb_current();
 535         if (lang) {
 536                 printf("Content-Language: %s\r\n", lang);
 537         }
 538
 539         printf("Content-Length: %d\r\n\r\n", (int)st.st_ex_size);
 540         while ((l=read(fd,buf,sizeof(buf)))>0) {
 541                 if (fwrite(buf, 1, l, stdout) != l) {
 542                         break;
 543                 }
 544         }
 545         close(fd);
 546         exit(0);
 547 }
 548
 549
 550
 551
 552 /**
 553  * @brief Setup the CGI framework.
 554  *
 555  * Setup the cgi framework, handling the possibility that this program
 556  * is either run as a true CGI program with a gateway to a web server, or
 557  * is itself a mini web server.
 558  **/
 559 void cgi_setup(const char *rootdir, int auth_required)
 560 {
 561         bool authenticated = False;
 562         char line[1024];
 563         char *url=NULL;
 564         char *p;
 565         char *lang;
 566
 567         if (chdir(rootdir)) {
 568                 cgi_setup_error("500 Server Error", "",
 569                                 "chdir failed - the server is not configured correctly");
 570         }
 571
 572         /* Handle the possibility we might be running as non-root */
 573         sec_init();
 574
 575         if ((lang=getenv("HTTP_ACCEPT_LANGUAGE"))) {
 576                 /* if running as a cgi program */
 577                 web_set_lang(lang);
 578         }
 579
 580         /* maybe we are running under a web server */
 581         if (getenv("CONTENT_LENGTH") || getenv("REQUEST_METHOD")) {
 582                 if (auth_required) {
 583                         cgi_web_auth();
 584                 }
 585                 return;
 586         }
 587
 588         inetd_server = True;
 589
 590         if (!check_access(1, lp_hostsallow(-1), lp_hostsdeny(-1))) {
 591                 cgi_setup_error("403 Forbidden", "",
 592                                 "Samba is configured to deny access from this client\n<br>Check your \"hosts allow\" and \"hosts deny\" options in smb.conf ");
 593         }
 594
 595         /* we are a mini-web server. We need to read the request from stdin
 596            and handle authentication etc */
 597         while (fgets(line, sizeof(line)-1, stdin)) {
 598                 if (line[0] == '\r' || line[0] == '\n') break;
 599                 if (strnequal(line,"GET ", 4)) {
 600                         got_request = True;
 601                         url = SMB_STRDUP(&line[4]);
 602                 } else if (strnequal(line,"POST ", 5)) {
 603                         got_request = True;
 604                         request_post = 1;
 605                         url = SMB_STRDUP(&line[5]);
 606                 } else if (strnequal(line,"PUT ", 4)) {
 607                         got_request = True;
 608                         cgi_setup_error("400 Bad Request", "",
 609                                         "This server does not accept PUT requests");
 610                 } else if (strnequal(line,"Authorization: ", 15)) {
 611                         authenticated = cgi_handle_authorization(&line[15]);
 612                 } else if (strnequal(line,"Content-Length: ", 16)) {
 613                         content_length = atoi(&line[16]);
 614                 } else if (strnequal(line,"Accept-Language: ", 17)) {
 615                         web_set_lang(&line[17]);
 616                 }
 617                 /* ignore all other requests! */
 618         }
 619
 620         if (auth_required && !authenticated) {
 621                 cgi_auth_error();
 622         }
 623
 624         if (!url) {
 625                 cgi_setup_error("400 Bad Request", "",
 626                                 "You must specify a GET or POST request");
 627         }
 628
 629         /* trim the URL */
 630         if ((p = strchr_m(url,' ')) || (p=strchr_m(url,'\t'))) {
 631                 *p = 0;
 632         }
 633         while (*url && strchr_m("\r\n",url[strlen(url)-1])) {
 634                 url[strlen(url)-1] = 0;
 635         }
 636
 637         /* anything following a ? in the URL is part of the query string */
 638         if ((p=strchr_m(url,'?'))) {
 639                 query_string = p+1;
 640                 *p = 0;
 641         }
 642
 643         string_sub(url, "/swat/", "", 0);
 644
 645         if (url[0] != '/' && strstr(url,"..")==0) {
 646                 cgi_download(url);
 647         }
 648
 649         printf("HTTP/1.0 200 OK\r\nConnection: close\r\n");
 650         printf("Date: %s\r\n", http_timestring(talloc_tos(), time(NULL)));
 651         baseurl = "";
 652         pathinfo = url+1;
 653 }
 654
 655
 656 /***************************************************************************
 657 return the current pages URL
 658   ***************************************************************************/
 659 const char *cgi_baseurl(void)
 660 {
 661         if (inetd_server) {
 662                 return baseurl;
 663         }
 664         return getenv("SCRIPT_NAME");
 665 }
 666
 667 /***************************************************************************
 668 return the current pages path info
 669   ***************************************************************************/
 670 const char *cgi_pathinfo(void)
 671 {
 672         char *r;
 673         if (inetd_server) {
 674                 return pathinfo;
 675         }
 676         r = getenv("PATH_INFO");
 677         if (!r) return "";
 678         if (*r == '/') r++;
 679         return r;
 680 }
 681
 682 /***************************************************************************
 683 return the hostname of the client
 684   ***************************************************************************/
 685 const char *cgi_remote_host(void)
 686 {
 687         if (inetd_server) {
 688                 return get_peer_name(1,False);
 689         }
 690         return getenv("REMOTE_HOST");
 691 }
 692
 693 /***************************************************************************
 694 return the hostname of the client
 695   ***************************************************************************/
 696 const char *cgi_remote_addr(void)
 697 {
 698         if (inetd_server) {
 699                 char addr[INET6_ADDRSTRLEN];
 700                 get_peer_addr(1,addr,sizeof(addr));
 701                 return talloc_strdup(talloc_tos(), addr);
 702         }
 703         return getenv("REMOTE_ADDR");
 704 }
 705
 706
 707 /***************************************************************************
 708 return True if the request was a POST
 709   ***************************************************************************/
 710 bool cgi_waspost(void)
 711 {
 712         if (inetd_server) {
 713                 return request_post;
 714         }
 715         return strequal(getenv("REQUEST_METHOD"), "POST");
 716 }