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 #define POST_LIMIT 131072
  42
  43 enum part {
  44         PART_UNKNOWN,
  45         PART_SESSIONID,
  46         PART_FILENAME,
  47         PART_FILEMODE,
  48         PART_FILEDATA
  49 };
  50
  51 const char *parts[] = {
  52         "(bug)",
  53         "sessionid",
  54         "filename",
  55         "filemode",
  56         "filedata",
  57 };
  58
  59 struct state
  60 {
  61         bool is_content_disposition;
  62         enum part parttype;
  63         char *sessionid;
  64         char *filename;
  65         bool filedata;
  66         int filemode;
  67         int filefd;
  68         int tempfd;
  69 };
  70
  71 enum {
  72         SES_ACCESS,
  73         __SES_MAX,
  74 };
  75
  76 static const struct blobmsg_policy ses_policy[__SES_MAX] = {
  77         [SES_ACCESS] = { .name = "access", .type = BLOBMSG_TYPE_BOOL },
  78 };
  79
  80
  81 static struct state st;
  82
  83 static void
  84 session_access_cb(struct ubus_request *req, int type, struct blob_attr *msg)
  85 {
  86         struct blob_attr *tb[__SES_MAX];
  87         bool *allow = (bool *)req->priv;
  88
  89         if (!msg)
  90                 return;
  91
  92         blobmsg_parse(ses_policy, __SES_MAX, tb, blob_data(msg), blob_len(msg));
  93
  94         if (tb[SES_ACCESS])
  95                 *allow = blobmsg_get_bool(tb[SES_ACCESS]);
  96 }
  97
  98 static bool
  99 session_access(const char *sid, const char *scope, const char *obj, const char *func)
 100 {
 101         uint32_t id;
 102         bool allow = false;
 103         struct ubus_context *ctx;
 104         static struct blob_buf req;
 105
 106         ctx = ubus_connect(NULL);
 107
 108         if (!ctx || ubus_lookup_id(ctx, "session", &id))
 109                 goto out;
 110
 111         blob_buf_init(&req, 0);
 112         blobmsg_add_string(&req, "ubus_rpc_session", sid);
 113         blobmsg_add_string(&req, "scope", scope);
 114         blobmsg_add_string(&req, "object", obj);
 115         blobmsg_add_string(&req, "function", func);
 116
 117         ubus_invoke(ctx, id, "access", req.head, session_access_cb, &allow, 500);
 118
 119 out:
 120         if (ctx)
 121                 ubus_free(ctx);
 122
 123         return allow;
 124 }
 125
 126 static char *
 127 checksum(const char *applet, size_t sumlen, const char *file)
 128 {
 129         pid_t pid;
 130         int r;
 131         int fds[2];
 132         static char chksum[65];
 133
 134         if (pipe(fds))
 135                 return NULL;
 136
 137         switch ((pid = fork()))
 138         {
 139         case -1:
 140                 return NULL;
 141
 142         case 0:
 143                 uloop_done();
 144
 145                 dup2(fds[1], 1);
 146
 147                 close(0);
 148                 close(2);
 149                 close(fds[0]);
 150                 close(fds[1]);
 151
 152                 if (execl("/bin/busybox", "/bin/busybox", applet, file, NULL))
 153                         return NULL;
 154
 155                 break;
 156
 157         default:
 158                 memset(chksum, 0, sizeof(chksum));
 159                 r = read(fds[0], chksum, sumlen);
 160
 161                 waitpid(pid, NULL, 0);
 162                 close(fds[0]);
 163                 close(fds[1]);
 164
 165                 if (r < 0)
 166                         return NULL;
 167         }
 168
 169         return chksum;
 170 }
 171
 172 static char *
 173 datadup(const void *in, size_t len)
 174 {
 175         char *out = malloc(len + 1);
 176
 177         if (!out)
 178                 return NULL;
 179
 180         memcpy(out, in, len);
 181
 182         *(out + len) = 0;
 183
 184         return out;
 185 }
 186
 187 static bool
 188 urldecode(char *buf)
 189 {
 190         char *c, *p;
 191
 192         if (!buf || !*buf)
 193                 return true;
 194
 195 #define hex(x) \
 196         (((x) <= '9') ? ((x) - '0') : \
 197                 (((x) <= 'F') ? ((x) - 'A' + 10) : \
 198                         ((x) - 'a' + 10)))
 199
 200         for (c = p = buf; *p; c++)
 201         {
 202                 if (*p == '%')
 203                 {
 204                         if (!isxdigit(*(p + 1)) || !isxdigit(*(p + 2)))
 205                                 return false;
 206
 207                         *c = (char)(16 * hex(*(p + 1)) + hex(*(p + 2)));
 208
 209                         p += 3;
 210                 }
 211                 else if (*p == '+')
 212                 {
 213                         *c = ' ';
 214                         p++;
 215                 }
 216                 else
 217                 {
 218                         *c = *p++;
 219                 }
 220         }
 221
 222         *c = 0;
 223
 224         return true;
 225 }
 226
 227 static char *
 228 postdecode(char **fields, int n_fields)
 229 {
 230         const char *var;
 231         char *p, *postbuf;
 232         int i, field, found = 0;
 233         ssize_t len = 0, rlen = 0, content_length = 0;
 234
 235         var = getenv("CONTENT_TYPE");
 236
 237         if (!var || strncmp(var, "application/x-www-form-urlencoded", 33))
 238                 return NULL;
 239
 240         var = getenv("CONTENT_LENGTH");
 241
 242         if (!var)
 243                 return NULL;
 244
 245         content_length = strtol(var, &p, 10);
 246
 247         if (p == var || content_length <= 0 || content_length >= POST_LIMIT)
 248                 return NULL;
 249
 250         postbuf = calloc(1, content_length + 1);
 251
 252         if (postbuf == NULL)
 253                 return NULL;
 254
 255         for (len = 0; len < content_length; )
 256         {
 257                 rlen = read(0, postbuf + len, content_length - len);
 258
 259                 if (rlen <= 0)
 260                         break;
 261
 262                 len += rlen;
 263         }
 264
 265         if (len < content_length)
 266         {
 267                 free(postbuf);
 268                 return NULL;
 269         }
 270
 271         for (p = postbuf, i = 0; i <= len; i++)
 272         {
 273                 if (postbuf[i] == '=')
 274                 {
 275                         postbuf[i] = 0;
 276
 277                         for (field = 0; field < (n_fields * 2); field += 2)
 278                         {
 279                                 if (!strcmp(p, fields[field]))
 280                                 {
 281                                         fields[field + 1] = postbuf + i + 1;
 282                                         found++;
 283                                 }
 284                         }
 285                 }
 286                 else if (postbuf[i] == '&' || postbuf[i] == '\0')
 287                 {
 288                         postbuf[i] = 0;
 289
 290                         if (found >= n_fields)
 291                                 break;
 292
 293                         p = postbuf + i + 1;
 294                 }
 295         }
 296
 297         for (field = 0; field < (n_fields * 2); field += 2)
 298         {
 299                 if (!urldecode(fields[field + 1]))
 300                 {
 301                         free(postbuf);
 302                         return NULL;
 303                 }
 304         }
 305
 306         return postbuf;
 307 }
 308
 309 static char *
 310 canonicalize_path(const char *path, size_t len)
 311 {
 312         char *canonpath, *cp;
 313         const char *p, *e;
 314
 315         if (path == NULL || *path == '\0')
 316                 return NULL;
 317
 318         canonpath = datadup(path, len);
 319
 320         if (canonpath == NULL)
 321                 return NULL;
 322
 323         /* normalize */
 324         for (cp = canonpath, p = path, e = path + len; p < e; ) {
 325                 if (*p != '/')
 326                         goto next;
 327
 328                 /* skip repeating / */
 329                 if ((p + 1 < e) && (p[1] == '/')) {
 330                         p++;
 331                         continue;
 332                 }
 333
 334                 /* /./ or /../ */
 335                 if ((p + 1 < e) && (p[1] == '.')) {
 336                         /* skip /./ */
 337                         if ((p + 2 >= e) || (p[2] == '/')) {
 338                                 p += 2;
 339                                 continue;
 340                         }
 341
 342                         /* collapse /x/../ */
 343                         if ((p + 2 < e) && (p[2] == '.') && ((p + 3 >= e) || (p[3] == '/'))) {
 344                                 while ((cp > canonpath) && (*--cp != '/'))
 345                                         ;
 346
 347                                 p += 3;
 348                                 continue;
 349                         }
 350                 }
 351
 352 next:
 353                 *cp++ = *p++;
 354         }
 355
 356         /* remove trailing slash if not root / */
 357         if ((cp > canonpath + 1) && (cp[-1] == '/'))
 358                 cp--;
 359         else if (cp == canonpath)
 360                 *cp++ = '/';
 361
 362         *cp = '\0';
 363
 364         return canonpath;
 365 }
 366
 367 static int
 368 response(bool success, const char *message)
 369 {
 370         char *chksum;
 371         struct stat s;
 372
 373         printf("Status: 200 OK\r\n");
 374         printf("Content-Type: text/plain\r\n\r\n{\n");
 375
 376         if (success)
 377         {
 378                 if (!stat(st.filename, &s))
 379                         printf("\t\"size\": %u,\n", (unsigned int)s.st_size);
 380                 else
 381                         printf("\t\"size\": null,\n");
 382
 383                 chksum = checksum("md5sum", 32, st.filename);
 384                 printf("\t\"checksum\": %s%s%s,\n",
 385                         chksum ? "\"" : "",
 386                         chksum ? chksum : "null",
 387                         chksum ? "\"" : "");
 388
 389                 chksum = checksum("sha256sum", 64, st.filename);
 390                 printf("\t\"sha256sum\": %s%s%s\n",
 391                         chksum ? "\"" : "",
 392                         chksum ? chksum : "null",
 393                         chksum ? "\"" : "");
 394         }
 395         else
 396         {
 397                 if (message)
 398                         printf("\t\"message\": \"%s\",\n", message);
 399
 400                 printf("\t\"failure\": [ %u, \"%s\" ]\n", errno, strerror(errno));
 401
 402                 if (st.filefd > -1)
 403                         unlink(st.filename);
 404         }
 405
 406         printf("}\n");
 407
 408         return -1;
 409 }
 410
 411 static int
 412 failure(int code, int e, const char *message)
 413 {
 414         printf("Status: %d %s\r\n", code, message);
 415         printf("Content-Type: text/plain\r\n\r\n");
 416         printf("%s", message);
 417
 418         if (e)
 419                 printf(": %s", strerror(e));
 420
 421         printf("\n");
 422
 423         return -1;
 424 }
 425
 426 static int
 427 filecopy(void)
 428 {
 429         int len;
 430         char buf[READ_BLOCK];
 431
 432         if (!st.filedata)
 433         {
 434                 close(st.tempfd);
 435                 errno = EINVAL;
 436                 return response(false, "No file data received");
 437         }
 438
 439         if (lseek(st.tempfd, 0, SEEK_SET) < 0)
 440         {
 441                 close(st.tempfd);
 442                 return response(false, "Failed to rewind temp file");
 443         }
 444
 445         st.filefd = open(st.filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
 446
 447         if (st.filefd < 0)
 448         {
 449                 close(st.tempfd);
 450                 return response(false, "Failed to open target file");
 451         }
 452
 453         while ((len = read(st.tempfd, buf, sizeof(buf))) > 0)
 454         {
 455                 if (write(st.filefd, buf, len) != len)
 456                 {
 457                         close(st.tempfd);
 458                         close(st.filefd);
 459                         return response(false, "I/O failure while writing target file");
 460                 }
 461         }
 462
 463         close(st.tempfd);
 464         close(st.filefd);
 465
 466         if (chmod(st.filename, st.filemode))
 467                 return response(false, "Failed to chmod target file");
 468
 469         return 0;
 470 }
 471
 472 static int
 473 header_field(multipart_parser *p, const char *data, size_t len)
 474 {
 475         st.is_content_disposition = !strncasecmp(data, "Content-Disposition", len);
 476         return 0;
 477 }
 478
 479 static int
 480 header_value(multipart_parser *p, const char *data, size_t len)
 481 {
 482         size_t i, j;
 483
 484         if (!st.is_content_disposition)
 485                 return 0;
 486
 487         if (len < 10 || strncasecmp(data, "form-data", 9))
 488                 return 0;
 489
 490         for (data += 9, len -= 9; *data == ' ' || *data == ';'; data++, len--);
 491
 492         if (len < 8 || strncasecmp(data, "name=\"", 6))
 493                 return 0;
 494
 495         for (data += 6, len -= 6, i = 0; i <= len; i++)
 496         {
 497                 if (*(data + i) != '"')
 498                         continue;
 499
 500                 for (j = 1; j < sizeof(parts) / sizeof(parts[0]); j++)
 501                         if (!strncmp(data, parts[j], i))
 502                                 st.parttype = j;
 503
 504                 break;
 505         }
 506
 507         return 0;
 508 }
 509
 510 static int
 511 data_begin_cb(multipart_parser *p)
 512 {
 513         char tmpname[24] = "/tmp/luci-upload.XXXXXX";
 514
 515         if (st.parttype == PART_FILEDATA)
 516         {
 517                 if (!st.sessionid)
 518                         return response(false, "File data without session");
 519
 520                 if (!st.filename)
 521                         return response(false, "File data without name");
 522
 523                 if (!session_access(st.sessionid, "file", st.filename, "write"))
 524                         return response(false, "Access to path denied by ACL");
 525
 526                 st.tempfd = mkstemp(tmpname);
 527
 528                 if (st.tempfd < 0)
 529                         return response(false, "Failed to create temporary file");
 530
 531                 unlink(tmpname);
 532         }
 533
 534         return 0;
 535 }
 536
 537 static int
 538 data_cb(multipart_parser *p, const char *data, size_t len)
 539 {
 540         int wlen = len;
 541
 542         switch (st.parttype)
 543         {
 544         case PART_SESSIONID:
 545                 st.sessionid = datadup(data, len);
 546                 break;
 547
 548         case PART_FILENAME:
 549                 st.filename = canonicalize_path(data, len);
 550                 break;
 551
 552         case PART_FILEMODE:
 553                 st.filemode = strtoul(data, NULL, 8);
 554                 break;
 555
 556         case PART_FILEDATA:
 557                 if (write(st.tempfd, data, len) != wlen)
 558                 {
 559                         close(st.tempfd);
 560                         return response(false, "I/O failure while writing temporary file");
 561                 }
 562
 563                 if (!st.filedata)
 564                         st.filedata = !!wlen;
 565
 566                 break;
 567
 568         default:
 569                 break;
 570         }
 571
 572         return 0;
 573 }
 574
 575 static int
 576 data_end_cb(multipart_parser *p)
 577 {
 578         if (st.parttype == PART_SESSIONID)
 579         {
 580                 if (!session_access(st.sessionid, "cgi-io", "upload", "write"))
 581                 {
 582                         errno = EPERM;
 583                         return response(false, "Upload permission denied");
 584                 }
 585         }
 586         else if (st.parttype == PART_FILEDATA)
 587         {
 588                 if (st.tempfd < 0)
 589                         return response(false, "Internal program failure");
 590
 591 #if 0
 592                 /* prepare directory */
 593                 for (ptr = st.filename; *ptr; ptr++)
 594                 {
 595                         if (*ptr == '/')
 596                         {
 597                                 *ptr = 0;
 598
 599                                 if (mkdir(st.filename, 0755))
 600                                 {
 601                                         unlink(st.tmpname);
 602                                         return response(false, "Failed to create destination directory");
 603                                 }
 604
 605                                 *ptr = '/';
 606                         }
 607                 }
 608 #endif
 609
 610                 if (filecopy())
 611                         return -1;
 612
 613                 return response(true, NULL);
 614         }
 615
 616         st.parttype = PART_UNKNOWN;
 617         return 0;
 618 }
 619
 620 static multipart_parser *
 621 init_parser(void)
 622 {
 623         char *boundary;
 624         const char *var;
 625
 626         multipart_parser *p;
 627         static multipart_parser_settings s = {
 628                 .on_part_data        = data_cb,
 629                 .on_headers_complete = data_begin_cb,
 630                 .on_part_data_end    = data_end_cb,
 631                 .on_header_field     = header_field,
 632                 .on_header_value     = header_value
 633         };
 634
 635         var = getenv("CONTENT_TYPE");
 636
 637         if (!var || strncmp(var, "multipart/form-data;", 20))
 638                 return NULL;
 639
 640         for (var += 20; *var && *var != '='; var++);
 641
 642         if (*var++ != '=')
 643                 return NULL;
 644
 645         boundary = malloc(strlen(var) + 3);
 646
 647         if (!boundary)
 648                 return NULL;
 649
 650         strcpy(boundary, "--");
 651         strcpy(boundary + 2, var);
 652
 653         st.tempfd = -1;
 654         st.filefd = -1;
 655         st.filemode = 0600;
 656
 657         p = multipart_parser_init(boundary, &s);
 658
 659         free(boundary);
 660
 661         return p;
 662 }
 663
 664 static int
 665 main_upload(int argc, char *argv[])
 666 {
 667         int rem, len;
 668         bool done = false;
 669         char buf[READ_BLOCK];
 670         multipart_parser *p;
 671
 672         p = init_parser();
 673
 674         if (!p)
 675         {
 676                 errno = EINVAL;
 677                 return response(false, "Invalid request");
 678         }
 679
 680         while ((len = read(0, buf, sizeof(buf))) > 0)
 681         {
 682                 if (!done) {
 683                         rem = multipart_parser_execute(p, buf, len);
 684                         done = (rem < len);
 685                 }
 686         }
 687
 688         multipart_parser_free(p);
 689
 690         return 0;
 691 }
 692
 693 static void
 694 free_charp(char **ptr)
 695 {
 696         free(*ptr);
 697 }
 698
 699 #define autochar __attribute__((__cleanup__(free_charp))) char
 700
 701 static int
 702 main_download(int argc, char **argv)
 703 {
 704         char *fields[] = { "sessionid", NULL, "path", NULL, "filename", NULL, "mimetype", NULL };
 705         unsigned long long size = 0;
 706         char *p, buf[READ_BLOCK];
 707         ssize_t len = 0;
 708         struct stat s;
 709         int rfd;
 710
 711         autochar *post = postdecode(fields, 4);
 712
 713         if (!fields[1] || !session_access(fields[1], "cgi-io", "download", "read"))
 714                 return failure(403, 0, "Download permission denied");
 715
 716         if (!fields[3] || !session_access(fields[1], "file", fields[3], "read"))
 717                 return failure(403, 0, "Access to path denied by ACL");
 718
 719         if (stat(fields[3], &s))
 720                 return failure(404, errno, "Failed to stat requested path");
 721
 722         if (!S_ISREG(s.st_mode) && !S_ISBLK(s.st_mode))
 723                 return failure(403, 0, "Requested path is not a regular file or block device");
 724
 725         for (p = fields[5]; p && *p; p++)
 726                 if (!isalnum(*p) && !strchr(" ()<>@,;:[]?.=%-", *p))
 727                         return failure(400, 0, "Invalid characters in filename");
 728
 729         for (p = fields[7]; p && *p; p++)
 730                 if (!isalnum(*p) && !strchr(" .;=/-", *p))
 731                         return failure(400, 0, "Invalid characters in mimetype");
 732
 733         rfd = open(fields[3], O_RDONLY);
 734
 735         if (rfd < 0)
 736                 return failure(500, errno, "Failed to open requested path");
 737
 738         if (S_ISBLK(s.st_mode))
 739                 ioctl(rfd, BLKGETSIZE64, &size);
 740         else
 741                 size = (unsigned long long)s.st_size;
 742
 743         printf("Status: 200 OK\r\n");
 744         printf("Content-Type: %s\r\n", fields[7] ? fields[7] : "application/octet-stream");
 745
 746         if (fields[5])
 747                 printf("Content-Disposition: attachment; filename=\"%s\"\r\n", fields[5]);
 748
 749         if (size > 0) {
 750                 printf("Content-Length: %llu\r\n\r\n", size);
 751                 fflush(stdout);
 752
 753                 while (size > 0) {
 754                         len = sendfile(1, rfd, NULL, size);
 755
 756                         if (len == -1) {
 757                                 if (errno == ENOSYS || errno == EINVAL) {
 758                                         while ((len = read(rfd, buf, sizeof(buf))) > 0)
 759                                                 fwrite(buf, len, 1, stdout);
 760
 761                                         fflush(stdout);
 762                                         break;
 763                                 }
 764
 765                                 if (errno == EINTR || errno == EAGAIN)
 766                                         continue;
 767                         }
 768
 769                         if (len <= 0)
 770                                 break;
 771
 772                         size -= len;
 773                 }
 774         }
 775         else {
 776                 printf("\r\n");
 777
 778                 while ((len = read(rfd, buf, sizeof(buf))) > 0)
 779                         fwrite(buf, len, 1, stdout);
 780
 781                 fflush(stdout);
 782         }
 783
 784         close(rfd);
 785
 786         return 0;
 787 }
 788
 789 static int
 790 main_backup(int argc, char **argv)
 791 {
 792         pid_t pid;
 793         time_t now;
 794         int r;
 795         int len;
 796         int status;
 797         int fds[2];
 798         char datestr[16] = { 0 };
 799         char hostname[64] = { 0 };
 800         char *fields[] = { "sessionid", NULL };
 801
 802         autochar *post = postdecode(fields, 1);
 803
 804         if (!fields[1] || !session_access(fields[1], "cgi-io", "backup", "read"))
 805                 return failure(403, 0, "Backup permission denied");
 806
 807         if (pipe(fds))
 808                 return failure(500, errno, "Failed to spawn pipe");
 809
 810         switch ((pid = fork()))
 811         {
 812         case -1:
 813                 return failure(500, errno, "Failed to fork process");
 814
 815         case 0:
 816                 dup2(fds[1], 1);
 817
 818                 close(0);
 819                 close(2);
 820                 close(fds[0]);
 821                 close(fds[1]);
 822
 823                 r = chdir("/");
 824                 if (r < 0)
 825                         return failure(500, errno, "Failed chdir('/')");
 826
 827                 execl("/sbin/sysupgrade", "/sbin/sysupgrade",
 828                       "--create-backup", "-", NULL);
 829
 830                 return -1;
 831
 832         default:
 833                 close(fds[1]);
 834
 835                 now = time(NULL);
 836                 strftime(datestr, sizeof(datestr) - 1, "%Y-%m-%d", localtime(&now));
 837
 838                 if (gethostname(hostname, sizeof(hostname) - 1))
 839                         sprintf(hostname, "OpenWrt");
 840
 841                 printf("Status: 200 OK\r\n");
 842                 printf("Content-Type: application/x-targz\r\n");
 843                 printf("Content-Disposition: attachment; "
 844                        "filename=\"backup-%s-%s.tar.gz\"\r\n\r\n", hostname, datestr);
 845
 846                 fflush(stdout);
 847
 848                 do {
 849                         len = splice(fds[0], NULL, 1, NULL, READ_BLOCK, SPLICE_F_MORE);
 850                 } while (len > 0);
 851
 852                 waitpid(pid, &status, 0);
 853
 854                 close(fds[0]);
 855
 856                 return 0;
 857         }
 858 }
 859
 860
 861 static const char *
 862 lookup_executable(const char *cmd)
 863 {
 864         size_t plen = 0, clen = strlen(cmd) + 1;
 865         static char path[PATH_MAX];
 866         char *search, *p;
 867         struct stat s;
 868
 869         if (!stat(cmd, &s) && S_ISREG(s.st_mode))
 870                 return cmd;
 871
 872         search = getenv("PATH");
 873
 874         if (!search)
 875                 search = "/bin:/usr/bin:/sbin:/usr/sbin";
 876
 877         p = search;
 878
 879         do {
 880                 if (*p != ':' && *p != '\0')
 881                         continue;
 882
 883                 plen = p - search;
 884
 885                 if ((plen + clen) >= sizeof(path))
 886                         continue;
 887
 888                 strncpy(path, search, plen);
 889                 sprintf(path + plen, "/%s", cmd);
 890
 891                 if (!stat(path, &s) && S_ISREG(s.st_mode))
 892                         return path;
 893
 894                 search = p + 1;
 895         } while (*p++);
 896
 897         return NULL;
 898 }
 899
 900 static char **
 901 parse_command(const char *cmdline)
 902 {
 903         const char *p = cmdline, *s;
 904         char **argv = NULL, *out;
 905         size_t arglen = 0;
 906         int argnum = 0;
 907         bool esc;
 908
 909         while (isspace(*cmdline))
 910                 cmdline++;
 911
 912         for (p = cmdline, s = p, esc = false; p; p++) {
 913                 if (esc) {
 914                         esc = false;
 915                 }
 916                 else if (*p == '\\' && p[1] != 0) {
 917                         esc = true;
 918                 }
 919                 else if (isspace(*p) || *p == 0) {
 920                         if (p > s) {
 921                                 argnum += 1;
 922                                 arglen += sizeof(char *) + (p - s) + 1;
 923                         }
 924
 925                         s = p + 1;
 926                 }
 927
 928                 if (*p == 0)
 929                         break;
 930         }
 931
 932         if (arglen == 0)
 933                 return NULL;
 934
 935         argv = calloc(1, arglen + sizeof(char *));
 936
 937         if (!argv)
 938                 return NULL;
 939
 940         out = (char *)argv + sizeof(char *) * (argnum + 1);
 941         argv[0] = out;
 942
 943         for (p = cmdline, s = p, esc = false, argnum = 0; p; p++) {
 944                 if (esc) {
 945                         esc = false;
 946                         *out++ = *p;
 947                 }
 948                 else if (*p == '\\' && p[1] != 0) {
 949                         esc = true;
 950                 }
 951                 else if (isspace(*p) || *p == 0) {
 952                         if (p > s) {
 953                                 *out++ = ' ';
 954                                 argv[++argnum] = out;
 955                         }
 956
 957                         s = p + 1;
 958                 }
 959                 else {
 960                         *out++ = *p;
 961                 }
 962
 963                 if (*p == 0)
 964                         break;
 965         }
 966
 967         argv[argnum] = NULL;
 968         out[-1] = 0;
 969
 970         return argv;
 971 }
 972
 973 static int
 974 main_exec(int argc, char **argv)
 975 {
 976         char *fields[] = { "sessionid", NULL, "command", NULL, "filename", NULL, "mimetype", NULL };
 977         int i, devnull, status, fds[2];
 978         bool allowed = false;
 979         ssize_t len = 0;
 980         const char *exe;
 981         char *p, **args;
 982         pid_t pid;
 983
 984         autochar *post = postdecode(fields, 4);
 985
 986         if (!fields[1] || !session_access(fields[1], "cgi-io", "exec", "read"))
 987                 return failure(403, 0, "Exec permission denied");
 988
 989         for (p = fields[5]; p && *p; p++)
 990                 if (!isalnum(*p) && !strchr(" ()<>@,;:[]?.=%-", *p))
 991                         return failure(400, 0, "Invalid characters in filename");
 992
 993         for (p = fields[7]; p && *p; p++)
 994                 if (!isalnum(*p) && !strchr(" .;=/-", *p))
 995                         return failure(400, 0, "Invalid characters in mimetype");
 996
 997         args = fields[3] ? parse_command(fields[3]) : NULL;
 998
 999         if (!args)
1000                 return failure(400, 0, "Invalid command parameter");
1001
1002         /* First check if we find an ACL match for the whole cmdline ... */
1003         allowed = session_access(fields[1], "file", args[0], "exec");
1004
1005         /* Now split the command vector... */
1006         for (i = 1; args[i]; i++)
1007                 args[i][-1] = 0;
1008
1009         /* Find executable... */
1010         exe = lookup_executable(args[0]);
1011
1012         if (!exe) {
1013                 free(args);
1014                 return failure(404, 0, "Executable not found");
1015         }
1016
1017         /* If there was no ACL match, check for a match on the executable */
1018         if (!allowed && !session_access(fields[1], "file", exe, "exec")) {
1019                 free(args);
1020                 return failure(403, 0, "Access to command denied by ACL");
1021         }
1022
1023         if (pipe(fds)) {
1024                 free(args);
1025                 return failure(500, errno, "Failed to spawn pipe");
1026         }
1027
1028         switch ((pid = fork()))
1029         {
1030         case -1:
1031                 free(args);
1032                 close(fds[0]);
1033                 close(fds[1]);
1034                 return failure(500, errno, "Failed to fork process");
1035
1036         case 0:
1037                 devnull = open("/dev/null", O_RDWR);
1038
1039                 if (devnull > -1) {
1040                         dup2(devnull, 0);
1041                         dup2(devnull, 2);
1042                         close(devnull);
1043                 }
1044                 else {
1045                         close(0);
1046                         close(2);
1047                 }
1048
1049                 dup2(fds[1], 1);
1050                 close(fds[0]);
1051                 close(fds[1]);
1052
1053                 if (chdir("/") < 0) {
1054                         free(args);
1055                         return failure(500, errno, "Failed chdir('/')");
1056                 }
1057
1058                 if (execv(exe, args) < 0) {
1059                         free(args);
1060                         return failure(500, errno, "Failed execv(...)");
1061                 }
1062
1063                 return -1;
1064
1065         default:
1066                 close(fds[1]);
1067
1068                 printf("Status: 200 OK\r\n");
1069                 printf("Content-Type: %s\r\n",
1070                        fields[7] ? fields[7] : "application/octet-stream");
1071
1072                 if (fields[5])
1073                         printf("Content-Disposition: attachment; filename=\"%s\"\r\n",
1074                                fields[5]);
1075
1076                 printf("\r\n");
1077                 fflush(stdout);
1078
1079                 do {
1080                         len = splice(fds[0], NULL, 1, NULL, READ_BLOCK, SPLICE_F_MORE);
1081                 } while (len > 0);
1082
1083                 waitpid(pid, &status, 0);
1084
1085                 close(fds[0]);
1086                 free(args);
1087
1088                 return 0;
1089         }
1090 }
1091
1092 int main(int argc, char **argv)
1093 {
1094         if (strstr(argv[0], "cgi-upload"))
1095                 return main_upload(argc, argv);
1096         else if (strstr(argv[0], "cgi-download"))
1097                 return main_download(argc, argv);
1098         else if (strstr(argv[0], "cgi-backup"))
1099                 return main_backup(argc, argv);
1100         else if (strstr(argv[0], "cgi-exec"))
1101                 return main_exec(argc, argv);
1102
1103         return -1;
1104 }