net/cgi-io/src/main.c

   1 /*
   2  * cgi-io - LuCI non-RPC helper
   3  *
   4  *   Copyright (C) 2013 Jo-Philipp Wich <jo@mein.io>
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #define _GNU_SOURCE /* splice(), SPLICE_F_MORE */
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <stdbool.h>
  24 #include <unistd.h>
  25 #include <string.h>
  26 #include <errno.h>
  27 #include <fcntl.h>
  28 #include <ctype.h>
  29 #include <sys/stat.h>
  30 #include <sys/wait.h>
  31 #include <sys/sendfile.h>
  32 #include <sys/ioctl.h>
  33 #include <linux/fs.h>
  34
  35 #include <libubus.h>
  36 #include <libubox/blobmsg.h>
  37
  38 #include "multipart_parser.h"
  39
  40 #define READ_BLOCK 4096
  41
  42 enum part {
  43         PART_UNKNOWN,
  44         PART_SESSIONID,
  45         PART_FILENAME,
  46         PART_FILEMODE,
  47         PART_FILEDATA
  48 };
  49
  50 const char *parts[] = {
  51         "(bug)",
  52         "sessionid",
  53         "filename",
  54         "filemode",
  55         "filedata",
  56 };
  57
  58 struct state
  59 {
  60         bool is_content_disposition;
  61         enum part parttype;
  62         char *sessionid;
  63         char *filename;
  64         bool filedata;
  65         int filemode;
  66         int filefd;
  67         int tempfd;
  68 };
  69
  70 enum {
  71         SES_ACCESS,
  72         __SES_MAX,
  73 };
  74
  75 static const struct blobmsg_policy ses_policy[__SES_MAX] = {
  76         [SES_ACCESS] = { .name = "access", .type = BLOBMSG_TYPE_BOOL },
  77 };
  78
  79
  80 static struct state st;
  81
  82 static void
  83 session_access_cb(struct ubus_request *req, int type, struct blob_attr *msg)
  84 {
  85         struct blob_attr *tb[__SES_MAX];
  86         bool *allow = (bool *)req->priv;
  87
  88         if (!msg)
  89                 return;
  90
  91         blobmsg_parse(ses_policy, __SES_MAX, tb, blob_data(msg), blob_len(msg));
  92
  93         if (tb[SES_ACCESS])
  94                 *allow = blobmsg_get_bool(tb[SES_ACCESS]);
  95 }
  96
  97 static bool
  98 session_access(const char *sid, const char *scope, const char *obj, const char *func)
  99 {
 100         uint32_t id;
 101         bool allow = false;
 102         struct ubus_context *ctx;
 103         static struct blob_buf req;
 104
 105         ctx = ubus_connect(NULL);
 106
 107         if (!ctx || ubus_lookup_id(ctx, "session", &id))
 108                 goto out;
 109
 110         blob_buf_init(&req, 0);
 111         blobmsg_add_string(&req, "ubus_rpc_session", sid);
 112         blobmsg_add_string(&req, "scope", scope);
 113         blobmsg_add_string(&req, "object", obj);
 114         blobmsg_add_string(&req, "function", func);
 115
 116         ubus_invoke(ctx, id, "access", req.head, session_access_cb, &allow, 500);
 117
 118 out:
 119         if (ctx)
 120                 ubus_free(ctx);
 121
 122         return allow;
 123 }
 124
 125 static char *
 126 checksum(const char *applet, size_t sumlen, const char *file)
 127 {
 128         pid_t pid;
 129         int r;
 130         int fds[2];
 131         static char chksum[65];
 132
 133         if (pipe(fds))
 134                 return NULL;
 135
 136         switch ((pid = fork()))
 137         {
 138         case -1:
 139                 return NULL;
 140
 141         case 0:
 142                 uloop_done();
 143
 144                 dup2(fds[1], 1);
 145
 146                 close(0);
 147                 close(2);
 148                 close(fds[0]);
 149                 close(fds[1]);
 150
 151                 if (execl("/bin/busybox", "/bin/busybox", applet, file, NULL))
 152                         return NULL;
 153
 154                 break;
 155
 156         default:
 157                 memset(chksum, 0, sizeof(chksum));
 158                 r = read(fds[0], chksum, sumlen);
 159
 160                 waitpid(pid, NULL, 0);
 161                 close(fds[0]);
 162                 close(fds[1]);
 163
 164                 if (r < 0)
 165                         return NULL;
 166         }
 167
 168         return chksum;
 169 }
 170
 171 static char *
 172 datadup(const void *in, size_t len)
 173 {
 174         char *out = malloc(len + 1);
 175
 176         if (!out)
 177                 return NULL;
 178
 179         memcpy(out, in, len);
 180
 181         *(out + len) = 0;
 182
 183         return out;
 184 }
 185
 186 static bool
 187 urldecode(char *buf)
 188 {
 189         char *c, *p;
 190
 191         if (!buf || !*buf)
 192                 return true;
 193
 194 #define hex(x) \
 195         (((x) <= '9') ? ((x) - '0') : \
 196                 (((x) <= 'F') ? ((x) - 'A' + 10) : \
 197                         ((x) - 'a' + 10)))
 198
 199         for (c = p = buf; *p; c++)
 200         {
 201                 if (*p == '%')
 202                 {
 203                         if (!isxdigit(*(p + 1)) || !isxdigit(*(p + 2)))
 204                                 return false;
 205
 206                         *c = (char)(16 * hex(*(p + 1)) + hex(*(p + 2)));
 207
 208                         p += 3;
 209                 }
 210                 else if (*p == '+')
 211                 {
 212                         *c = ' ';
 213                         p++;
 214                 }
 215                 else
 216                 {
 217                         *c = *p++;
 218                 }
 219         }
 220
 221         *c = 0;
 222
 223         return true;
 224 }
 225
 226 static bool
 227 postdecode(char **fields, int n_fields)
 228 {
 229         char *p;
 230         const char *var;
 231         static char buf[1024];
 232         int i, len, field, found = 0;
 233
 234         var = getenv("CONTENT_TYPE");
 235
 236         if (!var || strncmp(var, "application/x-www-form-urlencoded", 33))
 237                 return false;
 238
 239         memset(buf, 0, sizeof(buf));
 240
 241         if ((len = read(0, buf, sizeof(buf) - 1)) > 0)
 242         {
 243                 for (p = buf, i = 0; i <= len; i++)
 244                 {
 245                         if (buf[i] == '=')
 246                         {
 247                                 buf[i] = 0;
 248
 249                                 for (field = 0; field < (n_fields * 2); field += 2)
 250                                 {
 251                                         if (!strcmp(p, fields[field]))
 252                                         {
 253                                                 fields[field + 1] = buf + i + 1;
 254                                                 found++;
 255                                         }
 256                                 }
 257                         }
 258                         else if (buf[i] == '&' || buf[i] == '\0')
 259                         {
 260                                 buf[i] = 0;
 261
 262                                 if (found >= n_fields)
 263                                         break;
 264
 265                                 p = buf + i + 1;
 266                         }
 267                 }
 268         }
 269
 270         for (field = 0; field < (n_fields * 2); field += 2)
 271                 if (!urldecode(fields[field + 1]))
 272                         return false;
 273
 274         return (found >= n_fields);
 275 }
 276
 277 static char *
 278 canonicalize_path(const char *path, size_t len)
 279 {
 280         char *canonpath, *cp;
 281         const char *p, *e;
 282
 283         if (path == NULL || *path == '\0')
 284                 return NULL;
 285
 286         canonpath = datadup(path, len);
 287
 288         if (canonpath == NULL)
 289                 return NULL;
 290
 291         /* normalize */
 292         for (cp = canonpath, p = path, e = path + len; p < e; ) {
 293                 if (*p != '/')
 294                         goto next;
 295
 296                 /* skip repeating / */
 297                 if ((p + 1 < e) && (p[1] == '/')) {
 298                         p++;
 299                         continue;
 300                 }
 301
 302                 /* /./ or /../ */
 303                 if ((p + 1 < e) && (p[1] == '.')) {
 304                         /* skip /./ */
 305                         if ((p + 2 >= e) || (p[2] == '/')) {
 306                                 p += 2;
 307                                 continue;
 308                         }
 309
 310                         /* collapse /x/../ */
 311                         if ((p + 2 < e) && (p[2] == '.') && ((p + 3 >= e) || (p[3] == '/'))) {
 312                                 while ((cp > canonpath) && (*--cp != '/'))
 313                                         ;
 314
 315                                 p += 3;
 316                                 continue;
 317                         }
 318                 }
 319
 320 next:
 321                 *cp++ = *p++;
 322         }
 323
 324         /* remove trailing slash if not root / */
 325         if ((cp > canonpath + 1) && (cp[-1] == '/'))
 326                 cp--;
 327         else if (cp == canonpath)
 328                 *cp++ = '/';
 329
 330         *cp = '\0';
 331
 332         return canonpath;
 333 }
 334
 335 static int
 336 response(bool success, const char *message)
 337 {
 338         char *chksum;
 339         struct stat s;
 340
 341         printf("Status: 200 OK\r\n");
 342         printf("Content-Type: text/plain\r\n\r\n{\n");
 343
 344         if (success)
 345         {
 346                 if (!stat(st.filename, &s))
 347                         printf("\t\"size\": %u,\n", (unsigned int)s.st_size);
 348                 else
 349                         printf("\t\"size\": null,\n");
 350
 351                 chksum = checksum("md5sum", 32, st.filename);
 352                 printf("\t\"checksum\": %s%s%s,\n",
 353                         chksum ? "\"" : "",
 354                         chksum ? chksum : "null",
 355                         chksum ? "\"" : "");
 356
 357                 chksum = checksum("sha256sum", 64, st.filename);
 358                 printf("\t\"sha256sum\": %s%s%s\n",
 359                         chksum ? "\"" : "",
 360                         chksum ? chksum : "null",
 361                         chksum ? "\"" : "");
 362         }
 363         else
 364         {
 365                 if (message)
 366                         printf("\t\"message\": \"%s\",\n", message);
 367
 368                 printf("\t\"failure\": [ %u, \"%s\" ]\n", errno, strerror(errno));
 369
 370                 if (st.filefd > -1)
 371                         unlink(st.filename);
 372         }
 373
 374         printf("}\n");
 375
 376         return -1;
 377 }
 378
 379 static int
 380 failure(int code, int e, const char *message)
 381 {
 382         printf("Status: %d %s\r\n", code, message);
 383         printf("Content-Type: text/plain\r\n\r\n");
 384         printf("%s", message);
 385
 386         if (e)
 387                 printf(": %s", strerror(e));
 388
 389         printf("\n");
 390
 391         return -1;
 392 }
 393
 394 static int
 395 filecopy(void)
 396 {
 397         int len;
 398         char buf[READ_BLOCK];
 399
 400         if (!st.filedata)
 401         {
 402                 close(st.tempfd);
 403                 errno = EINVAL;
 404                 return response(false, "No file data received");
 405         }
 406
 407         if (lseek(st.tempfd, 0, SEEK_SET) < 0)
 408         {
 409                 close(st.tempfd);
 410                 return response(false, "Failed to rewind temp file");
 411         }
 412
 413         st.filefd = open(st.filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
 414
 415         if (st.filefd < 0)
 416         {
 417                 close(st.tempfd);
 418                 return response(false, "Failed to open target file");
 419         }
 420
 421         while ((len = read(st.tempfd, buf, sizeof(buf))) > 0)
 422         {
 423                 if (write(st.filefd, buf, len) != len)
 424                 {
 425                         close(st.tempfd);
 426                         close(st.filefd);
 427                         return response(false, "I/O failure while writing target file");
 428                 }
 429         }
 430
 431         close(st.tempfd);
 432         close(st.filefd);
 433
 434         if (chmod(st.filename, st.filemode))
 435                 return response(false, "Failed to chmod target file");
 436
 437         return 0;
 438 }
 439
 440 static int
 441 header_field(multipart_parser *p, const char *data, size_t len)
 442 {
 443         st.is_content_disposition = !strncasecmp(data, "Content-Disposition", len);
 444         return 0;
 445 }
 446
 447 static int
 448 header_value(multipart_parser *p, const char *data, size_t len)
 449 {
 450         size_t i, j;
 451
 452         if (!st.is_content_disposition)
 453                 return 0;
 454
 455         if (len < 10 || strncasecmp(data, "form-data", 9))
 456                 return 0;
 457
 458         for (data += 9, len -= 9; *data == ' ' || *data == ';'; data++, len--);
 459
 460         if (len < 8 || strncasecmp(data, "name=\"", 6))
 461                 return 0;
 462
 463         for (data += 6, len -= 6, i = 0; i <= len; i++)
 464         {
 465                 if (*(data + i) != '"')
 466                         continue;
 467
 468                 for (j = 1; j < sizeof(parts) / sizeof(parts[0]); j++)
 469                         if (!strncmp(data, parts[j], i))
 470                                 st.parttype = j;
 471
 472                 break;
 473         }
 474
 475         return 0;
 476 }
 477
 478 static int
 479 data_begin_cb(multipart_parser *p)
 480 {
 481         char tmpname[24] = "/tmp/luci-upload.XXXXXX";
 482
 483         if (st.parttype == PART_FILEDATA)
 484         {
 485                 if (!st.sessionid)
 486                         return response(false, "File data without session");
 487
 488                 if (!st.filename)
 489                         return response(false, "File data without name");
 490
 491                 if (!session_access(st.sessionid, "file", st.filename, "write"))
 492                         return response(false, "Access to path denied by ACL");
 493
 494                 st.tempfd = mkstemp(tmpname);
 495
 496                 if (st.tempfd < 0)
 497                         return response(false, "Failed to create temporary file");
 498
 499                 unlink(tmpname);
 500         }
 501
 502         return 0;
 503 }
 504
 505 static int
 506 data_cb(multipart_parser *p, const char *data, size_t len)
 507 {
 508         int wlen = len;
 509
 510         switch (st.parttype)
 511         {
 512         case PART_SESSIONID:
 513                 st.sessionid = datadup(data, len);
 514                 break;
 515
 516         case PART_FILENAME:
 517                 st.filename = canonicalize_path(data, len);
 518                 break;
 519
 520         case PART_FILEMODE:
 521                 st.filemode = strtoul(data, NULL, 8);
 522                 break;
 523
 524         case PART_FILEDATA:
 525                 if (write(st.tempfd, data, len) != wlen)
 526                 {
 527                         close(st.tempfd);
 528                         return response(false, "I/O failure while writing temporary file");
 529                 }
 530
 531                 if (!st.filedata)
 532                         st.filedata = !!wlen;
 533
 534                 break;
 535
 536         default:
 537                 break;
 538         }
 539
 540         return 0;
 541 }
 542
 543 static int
 544 data_end_cb(multipart_parser *p)
 545 {
 546         if (st.parttype == PART_SESSIONID)
 547         {
 548                 if (!session_access(st.sessionid, "cgi-io", "upload", "write"))
 549                 {
 550                         errno = EPERM;
 551                         return response(false, "Upload permission denied");
 552                 }
 553         }
 554         else if (st.parttype == PART_FILEDATA)
 555         {
 556                 if (st.tempfd < 0)
 557                         return response(false, "Internal program failure");
 558
 559 #if 0
 560                 /* prepare directory */
 561                 for (ptr = st.filename; *ptr; ptr++)
 562                 {
 563                         if (*ptr == '/')
 564                         {
 565                                 *ptr = 0;
 566
 567                                 if (mkdir(st.filename, 0755))
 568                                 {
 569                                         unlink(st.tmpname);
 570                                         return response(false, "Failed to create destination directory");
 571                                 }
 572
 573                                 *ptr = '/';
 574                         }
 575                 }
 576 #endif
 577
 578                 if (filecopy())
 579                         return -1;
 580
 581                 return response(true, NULL);
 582         }
 583
 584         st.parttype = PART_UNKNOWN;
 585         return 0;
 586 }
 587
 588 static multipart_parser *
 589 init_parser(void)
 590 {
 591         char *boundary;
 592         const char *var;
 593
 594         multipart_parser *p;
 595         static multipart_parser_settings s = {
 596                 .on_part_data        = data_cb,
 597                 .on_headers_complete = data_begin_cb,
 598                 .on_part_data_end    = data_end_cb,
 599                 .on_header_field     = header_field,
 600                 .on_header_value     = header_value
 601         };
 602
 603         var = getenv("CONTENT_TYPE");
 604
 605         if (!var || strncmp(var, "multipart/form-data;", 20))
 606                 return NULL;
 607
 608         for (var += 20; *var && *var != '='; var++);
 609
 610         if (*var++ != '=')
 611                 return NULL;
 612
 613         boundary = malloc(strlen(var) + 3);
 614
 615         if (!boundary)
 616                 return NULL;
 617
 618         strcpy(boundary, "--");
 619         strcpy(boundary + 2, var);
 620
 621         st.tempfd = -1;
 622         st.filefd = -1;
 623         st.filemode = 0600;
 624
 625         p = multipart_parser_init(boundary, &s);
 626
 627         free(boundary);
 628
 629         return p;
 630 }
 631
 632 static int
 633 main_upload(int argc, char *argv[])
 634 {
 635         int rem, len;
 636         bool done = false;
 637         char buf[READ_BLOCK];
 638         multipart_parser *p;
 639
 640         p = init_parser();
 641
 642         if (!p)
 643         {
 644                 errno = EINVAL;
 645                 return response(false, "Invalid request");
 646         }
 647
 648         while ((len = read(0, buf, sizeof(buf))) > 0)
 649         {
 650                 if (!done) {
 651                         rem = multipart_parser_execute(p, buf, len);
 652                         done = (rem < len);
 653                 }
 654         }
 655
 656         multipart_parser_free(p);
 657
 658         return 0;
 659 }
 660
 661 static int
 662 main_download(int argc, char **argv)
 663 {
 664         char *fields[] = { "sessionid", NULL, "path", NULL, "filename", NULL, "mimetype", NULL };
 665         unsigned long long size = 0;
 666         char *p, buf[READ_BLOCK];
 667         ssize_t len = 0;
 668         struct stat s;
 669         int rfd;
 670
 671         postdecode(fields, 4);
 672
 673         if (!fields[1] || !session_access(fields[1], "cgi-io", "download", "read"))
 674                 return failure(403, 0, "Download permission denied");
 675
 676         if (!fields[3] || !session_access(fields[1], "file", fields[3], "read"))
 677                 return failure(403, 0, "Access to path denied by ACL");
 678
 679         if (stat(fields[3], &s))
 680                 return failure(404, errno, "Failed to stat requested path");
 681
 682         if (!S_ISREG(s.st_mode) && !S_ISBLK(s.st_mode))
 683                 return failure(403, 0, "Requested path is not a regular file or block device");
 684
 685         for (p = fields[5]; p && *p; p++)
 686                 if (!isalnum(*p) && !strchr(" ()<>@,;:[]?.=%-", *p))
 687                         return failure(400, 0, "Invalid characters in filename");
 688
 689         for (p = fields[7]; p && *p; p++)
 690                 if (!isalnum(*p) && !strchr(" .;=/-", *p))
 691                         return failure(400, 0, "Invalid characters in mimetype");
 692
 693         rfd = open(fields[3], O_RDONLY);
 694
 695         if (rfd < 0)
 696                 return failure(500, errno, "Failed to open requested path");
 697
 698         if (S_ISBLK(s.st_mode))
 699                 ioctl(rfd, BLKGETSIZE64, &size);
 700         else
 701                 size = (unsigned long long)s.st_size;
 702
 703         printf("Status: 200 OK\r\n");
 704         printf("Content-Type: %s\r\n", fields[7] ? fields[7] : "application/octet-stream");
 705
 706         if (fields[5])
 707                 printf("Content-Disposition: attachment; filename=\"%s\"\r\n", fields[5]);
 708
 709         printf("Content-Length: %llu\r\n\r\n", size);
 710         fflush(stdout);
 711
 712         while (size > 0) {
 713                 len = sendfile(1, rfd, NULL, size);
 714
 715                 if (len == -1) {
 716                         if (errno == ENOSYS || errno == EINVAL) {
 717                                 while ((len = read(rfd, buf, sizeof(buf))) > 0)
 718                                         fwrite(buf, len, 1, stdout);
 719
 720                                 fflush(stdout);
 721                                 break;
 722                         }
 723
 724                         if (errno == EINTR || errno == EAGAIN)
 725                                 continue;
 726                 }
 727
 728                 if (len <= 0)
 729                         break;
 730
 731                 size -= len;
 732         }
 733
 734         close(rfd);
 735
 736         return 0;
 737 }
 738
 739 static int
 740 main_backup(int argc, char **argv)
 741 {
 742         pid_t pid;
 743         time_t now;
 744         int r;
 745         int len;
 746         int status;
 747         int fds[2];
 748         char datestr[16] = { 0 };
 749         char hostname[64] = { 0 };
 750         char *fields[] = { "sessionid", NULL };
 751
 752         if (!postdecode(fields, 1) || !session_access(fields[1], "cgi-io", "backup", "read"))
 753                 return failure(403, 0, "Backup permission denied");
 754
 755         if (pipe(fds))
 756                 return failure(500, errno, "Failed to spawn pipe");
 757
 758         switch ((pid = fork()))
 759         {
 760         case -1:
 761                 return failure(500, errno, "Failed to fork process");
 762
 763         case 0:
 764                 dup2(fds[1], 1);
 765
 766                 close(0);
 767                 close(2);
 768                 close(fds[0]);
 769                 close(fds[1]);
 770
 771                 r = chdir("/");
 772                 if (r < 0)
 773                         return failure(500, errno, "Failed chdir('/')");
 774
 775                 execl("/sbin/sysupgrade", "/sbin/sysupgrade",
 776                       "--create-backup", "-", NULL);
 777
 778                 return -1;
 779
 780         default:
 781                 now = time(NULL);
 782                 strftime(datestr, sizeof(datestr) - 1, "%Y-%m-%d", localtime(&now));
 783
 784                 if (gethostname(hostname, sizeof(hostname) - 1))
 785                         sprintf(hostname, "OpenWrt");
 786
 787                 printf("Status: 200 OK\r\n");
 788                 printf("Content-Type: application/x-targz\r\n");
 789                 printf("Content-Disposition: attachment; "
 790                        "filename=\"backup-%s-%s.tar.gz\"\r\n\r\n", hostname, datestr);
 791
 792                 fflush(stdout);
 793
 794                 do {
 795                         len = splice(fds[0], NULL, 1, NULL, READ_BLOCK, SPLICE_F_MORE);
 796                 } while (len > 0);
 797
 798                 waitpid(pid, &status, 0);
 799
 800                 close(fds[0]);
 801                 close(fds[1]);
 802
 803                 return 0;
 804         }
 805 }
 806
 807
 808 static const char *
 809 lookup_executable(const char *cmd)
 810 {
 811         size_t plen = 0, clen = strlen(cmd) + 1;
 812         static char path[PATH_MAX];
 813         char *search, *p;
 814         struct stat s;
 815
 816         if (!stat(cmd, &s) && S_ISREG(s.st_mode))
 817                 return cmd;
 818
 819         search = getenv("PATH");
 820
 821         if (!search)
 822                 search = "/bin:/usr/bin:/sbin:/usr/sbin";
 823
 824         p = search;
 825
 826         do {
 827                 if (*p != ':' && *p != '\0')
 828                         continue;
 829
 830                 plen = p - search;
 831
 832                 if ((plen + clen) >= sizeof(path))
 833                         continue;
 834
 835                 strncpy(path, search, plen);
 836                 sprintf(path + plen, "/%s", cmd);
 837
 838                 if (!stat(path, &s) && S_ISREG(s.st_mode))
 839                         return path;
 840
 841                 search = p + 1;
 842         } while (*p++);
 843
 844         return NULL;
 845 }
 846
 847 static char **
 848 parse_command(const char *cmdline)
 849 {
 850         const char *p = cmdline, *s;
 851         char **argv = NULL, *out;
 852         size_t arglen = 0;
 853         int argnum = 0;
 854         bool esc;
 855
 856         while (isspace(*cmdline))
 857                 cmdline++;
 858
 859         for (p = cmdline, s = p, esc = false; p; p++) {
 860                 if (esc) {
 861                         esc = false;
 862                 }
 863                 else if (*p == '\\' && p[1] != 0) {
 864                         esc = true;
 865                 }
 866                 else if (isspace(*p) || *p == 0) {
 867                         if (p > s) {
 868                                 argnum += 1;
 869                                 arglen += sizeof(char *) + (p - s) + 1;
 870                         }
 871
 872                         s = p + 1;
 873                 }
 874
 875                 if (*p == 0)
 876                         break;
 877         }
 878
 879         if (arglen == 0)
 880                 return NULL;
 881
 882         argv = calloc(1, arglen + sizeof(char *));
 883
 884         if (!argv)
 885                 return NULL;
 886
 887         out = (char *)argv + sizeof(char *) * (argnum + 1);
 888         argv[0] = out;
 889
 890         for (p = cmdline, s = p, esc = false, argnum = 0; p; p++) {
 891                 if (esc) {
 892                         esc = false;
 893                         *out++ = *p;
 894                 }
 895                 else if (*p == '\\' && p[1] != 0) {
 896                         esc = true;
 897                 }
 898                 else if (isspace(*p) || *p == 0) {
 899                         if (p > s) {
 900                                 *out++ = ' ';
 901                                 argv[++argnum] = out;
 902                         }
 903
 904                         s = p + 1;
 905                 }
 906                 else {
 907                         *out++ = *p;
 908                 }
 909
 910                 if (*p == 0)
 911                         break;
 912         }
 913
 914         argv[argnum] = NULL;
 915         out[-1] = 0;
 916
 917         return argv;
 918 }
 919
 920 static int
 921 main_exec(int argc, char **argv)
 922 {
 923         char *fields[] = { "sessionid", NULL, "command", NULL, "filename", NULL, "mimetype", NULL };
 924         int i, devnull, status, fds[2];
 925         bool allowed = false;
 926         ssize_t len = 0;
 927         const char *exe;
 928         char *p, **args;
 929         pid_t pid;
 930
 931         postdecode(fields, 4);
 932
 933         if (!fields[1] || !session_access(fields[1], "cgi-io", "exec", "read"))
 934                 return failure(403, 0, "Exec permission denied");
 935
 936         for (p = fields[5]; p && *p; p++)
 937                 if (!isalnum(*p) && !strchr(" ()<>@,;:[]?.=%-", *p))
 938                         return failure(400, 0, "Invalid characters in filename");
 939
 940         for (p = fields[7]; p && *p; p++)
 941                 if (!isalnum(*p) && !strchr(" .;=/-", *p))
 942                         return failure(400, 0, "Invalid characters in mimetype");
 943
 944         args = fields[3] ? parse_command(fields[3]) : NULL;
 945
 946         if (!args)
 947                 return failure(400, 0, "Invalid command parameter");
 948
 949         /* First check if we find an ACL match for the whole cmdline ... */
 950         allowed = session_access(fields[1], "file", args[0], "exec");
 951
 952         /* Now split the command vector... */
 953         for (i = 1; args[i]; i++)
 954                 args[i][-1] = 0;
 955
 956         /* Find executable... */
 957         exe = lookup_executable(args[0]);
 958
 959         if (!exe) {
 960                 free(args);
 961                 return failure(404, 0, "Executable not found");
 962         }
 963
 964         /* If there was no ACL match, check for a match on the executable */
 965         if (!allowed && !session_access(fields[1], "file", exe, "exec")) {
 966                 free(args);
 967                 return failure(403, 0, "Access to command denied by ACL");
 968         }
 969
 970         if (pipe(fds)) {
 971                 free(args);
 972                 return failure(500, errno, "Failed to spawn pipe");
 973         }
 974
 975         switch ((pid = fork()))
 976         {
 977         case -1:
 978                 free(args);
 979                 close(fds[0]);
 980                 close(fds[1]);
 981                 return failure(500, errno, "Failed to fork process");
 982
 983         case 0:
 984                 devnull = open("/dev/null", O_RDWR);
 985
 986                 if (devnull > -1) {
 987                         dup2(devnull, 0);
 988                         dup2(devnull, 2);
 989                         close(devnull);
 990                 }
 991                 else {
 992                         close(0);
 993                         close(2);
 994                 }
 995
 996                 dup2(fds[1], 1);
 997                 close(fds[0]);
 998                 close(fds[1]);
 999
1000                 if (chdir("/") < 0) {
1001                         free(args);
1002                         return failure(500, errno, "Failed chdir('/')");
1003                 }
1004
1005                 if (execv(exe, args) < 0) {
1006                         free(args);
1007                         return failure(500, errno, "Failed execv(...)");
1008                 }
1009
1010                 return -1;
1011
1012         default:
1013                 printf("Status: 200 OK\r\n");
1014                 printf("Content-Type: %s\r\n",
1015                        fields[7] ? fields[7] : "application/octet-stream");
1016
1017                 if (fields[5])
1018                         printf("Content-Disposition: attachment; filename=\"%s\"\r\n",
1019                                fields[5]);
1020
1021                 printf("\r\n");
1022                 fflush(stdout);
1023
1024                 do {
1025                         len = splice(fds[0], NULL, 1, NULL, READ_BLOCK, SPLICE_F_MORE);
1026                 } while (len > 0);
1027
1028                 waitpid(pid, &status, 0);
1029
1030                 close(fds[0]);
1031                 close(fds[1]);
1032                 free(args);
1033
1034                 return 0;
1035         }
1036 }
1037
1038 int main(int argc, char **argv)
1039 {
1040         if (strstr(argv[0], "cgi-upload"))
1041                 return main_upload(argc, argv);
1042         else if (strstr(argv[0], "cgi-download"))
1043                 return main_download(argc, argv);
1044         else if (strstr(argv[0], "cgi-backup"))
1045                 return main_backup(argc, argv);
1046         else if (strstr(argv[0], "cgi-exec"))
1047                 return main_exec(argc, argv);
1048
1049         return -1;
1050 }