source: trunk/src/trustfile.c@ 220

Last change on this file since 220 was 220, checked in by katerina, 16 years ago

Fix problem with standalone trustfile (ticket #147).
File size: 27.6 KB
Line 
1/* debug problems */
2/* #define TRUST_DEBUG */
3
4/* switch off full check */
5/* #define TEST_ONLY */
6
7/* standalone */
8/* #define TRUST_MAIN */
9/* $(CC) -DTRUST_MAIN -DSL_ALWAYS_TRUSTED=... */
10
11/* LINTLIBRARY */
12/*
13 * This is the file with all the library routines in it
14 *
15 * Author information:
16 * Matt Bishop
17 * Department of Computer Science
18 * University of California at Davis
19 * Davis, CA 95616-8562
20 * phone (916) 752-8060
21 * email bishop@cs.ucdavis.edu
22 *
23 * This code is placed in the public domain. I do ask that
24 * you keep my name associated with it, that you not represent
25 * it as written by you, and that you preserve these comments.
26 * This software is provided "as is" and without any guarantees
27 * of any sort.
28 *
29 * Compilation notes:
30 * * this does NOT use malloc(3), but fixed storage. this means we
31 * do lots of bounds checking, but it still is faster, and smaller,
32 * than forcing inclusion of malloc. All buffers etc. are of size
33 * MAXFILENAME (defined in trustfile.h); to get more room, recompile
34 * with this set larger.
35 * * if you support the following directory semantics, define STICKY;
36 * otherwise, undefine it
37 * "if a directory is both world-writeable AND has the sticky bit
38 * set, then ONLY the owner of an existing file may delete it"
39 * On some systems (eg, IRIX), you can delete the file under these
40 * conditions if the file is world writeable. Foor our purposes,
41 * this is irrelevant since if the file is world-writeable it is
42 * untrustworthy; either it can be replaced with another file (the
43 * IRIX version) or it can be altered (all versions).
44 * if this is true and STICKY is not set, the sticky bit is ignored
45 * and the directory will be flagged as untrustworthy, even when only
46 * a trusted user could delete the file
47 * * this uses a library call to get the name of the current working
48 * directory. Define the following to get the various versions:
49 * GETCWD for Solaris 2.x, SunOS 4.1.x, IRIX 5.x
50 * char *getcwd(char *buf, int bufsz);
51 * where buf is a buffer for the path name, and bufsz is
52 * the size of the buffer; if the size if too small, you
53 * get an error return (NULL)
54 * GETWD for Ultrix 4.4
55 * char *getwd(char *buf)
56 * where buf is a buffer for the path name, and it is
57 * assumed to be at lease as big as MAXPATHLEN.
58 * *** IMPORTANT NOTE ***
59 * Ultrix supports getcwd as well, but it uses popen to
60 * run the command "pwd" (according to the manual). This
61 * means it's vulnerable to a number of attacks if used
62 * in a privileged program. YOU DON'T WANT THIS.
63 * * the debugging flag DEBUG prints out each step of the file name
64 * checking, as well as info on symbolic links (if S_IFLNK defined),
65 * file name canonicalization, and user, group, and permission for
66 * each file or directory; this is useful if you want to be sure
67 * you're checking the right file
68 *
69 * Version information:
70 * 1.0 December 28, 1995 Matt Bishop
71 *
72 * 2.0 March 26, 2000 Rainer Wichmann -- adapted for slib.
73 */
74
75/* --- Why strcpy is safe here: ---- */
76
77/* The input path is checked once, and then either shortened [in dirz()],
78 * or safely expanded (symlinks) with bound checking.
79 * I.e., the path length can never exceed (MAXFILENAME-1), while the path
80 * is always copied between buffers of length MAXFILENAME.
81 */
82
83#ifndef TRUST_MAIN
84#include "config_xor.h"
85#include "sh_calls.h"
86#else
87#define UID_CAST long
88#define HAVE_GETPWENT
89#define SH_MUTEX_LOCK(a) ((void)0)
90#define SH_MUTEX_UNLOCK(a) ((void)0)
91#endif
92
93#include <stdio.h>
94#include <stdlib.h>
95#include <sys/types.h>
96#include <sys/stat.h>
97#include <grp.h>
98#include <pwd.h>
99#include <string.h>
100#include <unistd.h>
101
102
103#ifndef TRUST_MAIN
104
105#include "slib.h"
106#define SH_NEED_PWD_GRP 1
107#include "sh_static.h"
108#include "sh_pthread.h"
109
110#else
111
112#define sh_getgrgid getgrgid
113#define sh_getgrgid_r getgrgid_r
114#define sh_getpwnam getpwnam
115#define sh_getpwnam_r getpwnam_r
116#define sh_getpwuid getpwuid
117#define sh_getpwuid_r getpwuid_r
118#define sh_getpwent getpwent
119#define sh_endpwent endpwent
120
121#define TRUST_DEBUG
122#define SL_FALSE 0
123#define SL_TRUE 1
124#define SL_ENTER(string)
125#define SL_IRETURN(a, b) return a
126#define retry_lstat(a,b,c,d) lstat(c,d)
127#define _(string) string
128#define N_(string) string
129#define MAXFILENAME 4096
130static int sl_errno = 0;
131#define SL_ENONE 0
132#define SL_ENULL -1024 /* Invalid use of NULL pointer. */
133#define SL_ERANGE -1025 /* Argument out of range. */
134#define SL_ETRUNC -1026 /* Result truncated. */
135#define SL_EINTERNAL -1028 /* Internal error. */
136#define SL_EBADFILE -1030 /* File access error. Check errno. */
137#define SL_EBADNAME -1040 /* Invalid name. */
138#define SL_ESTAT -1041 /* stat of file failed. Check errno. */
139#define SL_EBADUID -1050 /* Owner not trustworthy. */
140#define SL_EBADGID -1051 /* Group writeable and not trustworthy.*/
141#define SL_EBADOTH -1052 /* World writeable. */
142
143#endif
144
145
146#if defined(__linux__) || defined(__FreeBSD__)
147#define STICKY
148#endif
149
150#undef FIL__
151#define FIL__ _("trustfile.c")
152
153/*
154 * the get current working directory function
155 * every version of UNIX seems to have its own
156 * idea of how to do this, so we group them by
157 * arguments ...
158 * all must return a pointer to the right name
159 */
160
161
162#ifndef TRUST_MAIN
163
164#if defined(HAVE_GETCWD) && !defined(HAVE_BROKEN_GETCWD)
165#define CURDIR(buf,nbuf) getcwd((buf), (nbuf))
166#elif defined(HAVE_GETWD)
167#define CURDIR(buf,nbuf) getwd((buf))
168#endif
169
170#else
171
172#define CURDIR(buf,nbuf) getcwd((buf), (nbuf))
173
174#endif
175
176
177
178/*
179 * this checks to see if there are symbolic links
180 * assumes the link bit in the protection mask is called S_IFLNK
181 * (seems to be true on all UNIXes with them)
182 */
183#ifndef S_IFLNK
184#define lstat stat
185#endif
186
187
188/*
189 * these are useful global variables
190 *
191 * first set: who you gonna trust, by default?
192 * if the user does not specify a trusted or untrusted set of users,
193 * all users are considered untrusted EXCEPT:
194 * UID 0 -- root as root can do anything on most UNIX systems, this
195 * seems reasonable
196 * tf_euid -- programmer-selectable UID
197 * if the caller specifies a specific UID by putting
198 * it in this variable, it will be trusted; this is
199 * typically used to trust the effective UID of the
200 * process (note: NOT the real UID, which will cause all
201 * sorts of problems!) By default, this is set to -1,
202 * so if it's not set, root is the only trusted user
203 */
204
205/* modified Tue Feb 22 10:36:44 NFT 2000 Rainer Wichmann */
206
207
208#ifndef SL_ALWAYS_TRUSTED
209#define SL_ALWAYS_TRUSTED 0
210#endif
211static uid_t test_rootonly[] = { SL_ALWAYS_TRUSTED };
212
213#define tf_uid_neg ((uid_t)-1)
214
215uid_t rootonly[] = { SL_ALWAYS_TRUSTED,
216 tf_uid_neg, tf_uid_neg, tf_uid_neg, tf_uid_neg,
217 tf_uid_neg, tf_uid_neg, tf_uid_neg, tf_uid_neg,
218 tf_uid_neg, tf_uid_neg, tf_uid_neg, tf_uid_neg,
219 tf_uid_neg, tf_uid_neg, tf_uid_neg, tf_uid_neg };
220
221uid_t tf_euid = tf_uid_neg;
222int EUIDSLOT = sizeof(test_rootonly)/sizeof(uid_t);
223int ORIG_EUIDSLOT = sizeof(test_rootonly)/sizeof(uid_t);
224
225char tf_path[MAXFILENAME]; /* error path for trust function */
226uid_t tf_baduid;
227gid_t tf_badgid;
228
229static
230int dirz(char *path)
231{
232 register char *p = path;/* points to rest of path to clean up */
233 register char *q; /* temp pointer for skipping over stuff */
234
235 static char swp[MAXFILENAME];
236
237 SL_ENTER(_("dirz"));
238 /*
239 * standard error checking
240 */
241 if (path == NULL)
242 SL_IRETURN(SL_ENULL, _("dirz"));
243 if (path[0] == '.')
244 SL_IRETURN(SL_EINTERNAL, _("dirz"));
245
246
247 /*
248 * loop over the path name until everything is checked
249 */
250 while(*p)
251 {
252 /* skip
253 */
254 if (*p != '/')
255 {
256 p++;
257 continue;
258 }
259
260 /* "/./" or "/."
261 */
262 if (p[1] == '.' && (p[2] == '/' || p[2] == '\0'))
263 {
264 /* yes -- delete "/."
265 */
266 (void) strcpy(swp, &p[2]); /* known to fit */
267 (void) strcpy(p, swp); /* known to fit */
268
269 /* special case "/." as full path name
270 */
271 if (p == path && *p == '\0')
272 {
273 *p++ = '/';
274 *p = '\0';
275 }
276 }
277
278 /* "//"
279 */
280 else if (p[1] == '/')
281 {
282 /* yes -- skip
283 */
284 for(q = &p[2]; *q == '/'; q++)
285 ;
286 (void) strcpy(swp, q); /* known to fit */
287 (void) strcpy(&p[1], swp); /* known to fit */
288 }
289
290 /* "/../" or "/.."
291 */
292 else if (p[1] == '.' && p[2] == '.' && (p[3] == '/' || p[3] == '\0'))
293 {
294 /* yes -- if it's root, delete .. only
295 */
296 if (p == path)
297 {
298 (void) strcpy(swp, &p[3]); /* known to fit */
299 (void) strcpy(p, swp); /* known to fit */
300 }
301 else
302 {
303 /* back up over previous component
304 */
305 q = p - 1;
306 while(q != path && *q != '/')
307 q--;
308 /* now wipe it out
309 */
310 (void) strcpy(swp, &p[3]); /* known to fit */
311 (void) strcpy(q, swp); /* known to fit */
312 p = q;
313 }
314 }
315 else
316 p++;
317 }
318 SL_IRETURN(SL_ENONE, _("dirz"));
319}
320
321
322
323/* not static to circumvent stupid gcc 4 bug */
324int getfname(const char *fname, char *rbuf, int rsz)
325{
326#ifndef TRUST_MAIN
327 register int status;
328#endif
329
330 SL_ENTER(_("getfname"));
331 /*
332 * do the initial checking
333 * NULL pointer
334 */
335 if (fname == NULL || rbuf == NULL)
336 SL_IRETURN(SL_ENULL, _("getfname"));
337 if (rsz <= 0)
338 SL_IRETURN(SL_ERANGE, _("getfname"));
339
340
341 /* already a full path name */
342 if (*fname == '/')
343 rbuf[0] = '\0';
344 else
345 {
346 if (CURDIR(rbuf, rsz) == NULL)
347 {
348#ifdef TRUST_DEBUG
349 fprintf(stderr, "trustfile: getcwd failed\n");
350#endif
351 SL_IRETURN(SL_EBADNAME, _("getfname"));
352 }
353 }
354
355 /*
356 * append the file name and reduce
357 */
358 if (fname != NULL && *fname != '\0')
359 {
360#ifndef TRUST_MAIN
361 status = sl_strlcat(rbuf, "/", rsz);
362 if (status == SL_ENONE)
363 status = sl_strlcat(rbuf, fname, rsz);
364 if (status != SL_ENONE)
365 SL_IRETURN(status, _("getfname"));
366#else
367 strncat(rbuf, "/", rsz-strlen(rbuf)-1);
368 strncat(rbuf, fname, rsz-strlen(rbuf)-1);
369 rbuf[rsz-1] = '\0';
370#endif
371 }
372 SL_IRETURN(dirz(rbuf), _("getfname"));
373}
374
375static
376int isin(uid_t n, uid_t *list)
377{
378 SL_ENTER(_("isin"));
379 if (list == NULL)
380 SL_IRETURN(SL_FALSE, _("isin"));
381
382 while(*list != tf_uid_neg && *list != n)
383 {
384#ifdef TRUST_DEBUG
385 fprintf (stderr,
386 "trustfile: owner_uid=%ld, trusted uid=%ld, no match\n",
387 (UID_CAST) n, (UID_CAST) *list);
388#endif
389 list++;
390 }
391
392 if (*list == tf_uid_neg)
393 {
394#ifdef TRUST_DEBUG
395 fprintf (stderr,
396 "trustfile: owner_uid=%ld, no match with any trusted user --> ERROR\n",
397 (UID_CAST) n);
398#endif
399 SL_IRETURN(SL_FALSE, _("isin"));
400 }
401
402#ifdef TRUST_DEBUG
403 fprintf (stderr,
404 "trustfile: owner_uid=%ld, trusted_uid=%ld, match found --> OK\n",
405 (UID_CAST)n, (UID_CAST)*list);
406#endif
407 SL_IRETURN(SL_TRUE, _("isin"));
408}
409
410/* comment added by R. Wichmann
411 * RETURN TRUE if ANYONE in ulist is group member
412 */
413/* not static to circumvent stupid gcc 4 bug */
414int isingrp(gid_t grp, uid_t *ulist)
415{
416 struct passwd *w; /* info about group member */
417 register uid_t *u; /* points to current ulist member */
418 register char **p; /* points to current group member */
419 struct group *g; /* pointer to group information */
420
421#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
422 struct group gr;
423 char buffer[SH_GRBUF_SIZE];
424 struct passwd pwd;
425 char pbuffer[SH_PWBUF_SIZE];
426#endif
427
428 SL_ENTER(_("isingrp"));
429
430#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
431 sh_getgrgid_r(grp, &gr, buffer, sizeof(buffer), &g);
432#else
433 g = sh_getgrgid(grp);
434#endif
435
436 if (g == NULL)
437 {
438 SL_IRETURN(SL_FALSE, _("isingrp") );
439 }
440 /*
441 if(g->gr_mem == NULL || g->gr_mem[0] == NULL )
442 SL_IRETURN(SL_FALSE, _("isingrp") );
443 */
444
445 /* this will return at the first match
446 */
447 for(p = g->gr_mem; *p != NULL; p++)
448 {
449 for(u = ulist; *u != tf_uid_neg; u++)
450 {
451 /* map user name to UID and compare */
452#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETPWNAM_R)
453 sh_getpwnam_r(*p, &pwd, pbuffer, sizeof(pbuffer), &w);
454#else
455 w = sh_getpwnam(*p);
456#endif
457
458#ifdef TRUST_MAIN
459 if (w != NULL && *u == (uid_t)(w->pw_uid) )
460 SL_IRETURN(SL_TRUE, _("isingrp"));
461#else
462 if (w != NULL && *u == (uid_t)(w->pw_uid) )
463 {
464 SL_IRETURN(SL_TRUE, _("isingrp"));
465 }
466#endif
467 }
468 }
469 /* added by R. Wichmann Fri Mar 30 08:16:14 CEST 2001:
470 * a user can have a GID but no entry in /etc/group
471 */
472 for(u = ulist; *u != tf_uid_neg; u++)
473 {
474#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETPWUID_R)
475 sh_getpwuid_r(*u, &pwd, pbuffer, sizeof(pbuffer), &w);
476#else
477 w = sh_getpwuid(*u);
478#endif
479#ifdef TRUST_MAIN
480 if (w != NULL && grp == (gid_t)(w->pw_gid) )
481 SL_IRETURN(SL_TRUE, _("isingrp"));
482#else
483 if (w != NULL && grp == (gid_t)(w->pw_gid) )
484 {
485 SL_IRETURN(SL_TRUE, _("isingrp"));
486 }
487#endif
488 }
489
490 SL_IRETURN(SL_FALSE, _("isingrp"));
491}
492
493/* added by R. Wichmann Fri Mar 30 08:16:14 CEST 2001
494 * RETURN TRUE only if ALL group members are trusted
495 */
496/* not static to circumvent stupid gcc 4 bug */
497int onlytrustedingrp(gid_t grp, uid_t *ulist)
498{
499 struct passwd *w; /* info about group member */
500 register uid_t *u; /* points to current ulist member */
501 register char **p; /* points to current group member */
502 struct group *g; /* pointer to group information */
503 register int flag = -1; /* group member found */
504
505#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
506 struct group gr;
507 char buffer[SH_GRBUF_SIZE];
508 struct passwd pw;
509 char pbuffer[SH_PWBUF_SIZE];
510#endif
511
512 int retval = SL_FALSE;
513
514 SL_ENTER(_("onlytrustedingrp"));
515
516#ifdef TRUST_DEBUG
517 fprintf(stderr, "trustfile: group writeable, group_gid: %ld\n",
518 (UID_CAST)grp);
519#endif
520
521#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
522 sh_getgrgid_r(grp, &gr, buffer, sizeof(buffer), &g);
523#else
524 g = sh_getgrgid(grp);
525#endif
526
527 if (g == NULL)
528 {
529#ifdef TRUST_DEBUG
530 fprintf(stderr,
531 "trustfile: group_gid: %ld, no such group --> ERROR\n",
532 (UID_CAST)grp);
533#endif
534 SL_IRETURN(SL_FALSE, _("onlytrustedingrp") );
535 }
536
537 /* empty group -> no problem
538
539 if(g->gr_mem == NULL || g->gr_mem[0] == NULL )
540 SL_IRETURN(SL_TRUE, _("onlytrustedingrp") );
541 */
542
543 /* check for untrusted members of the group
544 */
545 for(p = g->gr_mem; *p != NULL; p++)
546 {
547 flag = -1;
548#ifdef TRUST_DEBUG
549 fprintf(stderr, "trustfile: group_member: %s\n", *p);
550#endif
551 /* map user name to UID and compare
552 */
553#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETPWNAM_R)
554 sh_getpwnam_r(*p, &pw, pbuffer, sizeof(pbuffer), &w);
555#else
556 w = sh_getpwnam(*p);
557#endif
558
559 if (w == NULL) /* not a valid user, ignore */
560 {
561 flag = 0;
562 }
563 else /* check list of trusted users */
564 {
565#ifdef TRUST_DEBUG
566 fprintf (stderr,
567 "trustfile: uid=%ld, checking whether it is trusted\n",
568 (UID_CAST)(w->pw_uid));
569#endif
570 for(u = ulist; *u != tf_uid_neg; u++)
571 {
572 if (*u == (w->pw_uid) )
573 {
574#ifdef TRUST_DEBUG
575 fprintf (stderr,
576 "trustfile: uid=%ld, trusted_uid=%ld, match found --> OK\n",
577 (UID_CAST)(w->pw_uid), (UID_CAST)*u);
578#endif
579 flag = 0;
580 break;
581 }
582 else
583 {
584#ifdef TRUST_DEBUG
585 fprintf (stderr,
586 "trustfile: uid=%ld, trusted_uid=%ld, no match\n",
587 (UID_CAST)(w->pw_uid), (UID_CAST)*u);
588#endif
589 ;
590 }
591 }
592 }
593 /* not found
594 */
595 if (flag == -1)
596 {
597#ifdef TRUST_DEBUG
598 fprintf (stderr,
599 "trustfile: user=%s (gid %ld), not a trusted user --> ERROR\n", *p, (UID_CAST)grp);
600#endif
601 tf_baduid = w->pw_uid;
602 SL_IRETURN(SL_FALSE, _("onlytrustedingrp"));
603 }
604 }
605
606#ifndef TEST_ONLY
607#ifdef HAVE_GETPWENT
608 /* now check ALL users for their GID !!!
609 */
610 SH_MUTEX_LOCK(mutex_pwent);
611
612 while (NULL != (w = sh_getpwent()))
613 {
614 if (grp == (gid_t)(w->pw_gid))
615 {
616#ifdef TRUST_DEBUG
617 fprintf(stderr, "trustfile: checking group member %s, uid %ld\n",
618 w->pw_name, (UID_CAST)w->pw_uid);
619#endif
620 /* is it a trusted user ?
621 */
622 flag = -1;
623 for(u = ulist; *u != tf_uid_neg; u++)
624 {
625 if (*u == (uid_t)(w->pw_uid))
626 {
627#ifdef TRUST_DEBUG
628 fprintf (stderr,
629 "trustfile: uid=%ld, trusted_uid=%ld, match found --> OK\n",
630 (UID_CAST)(w->pw_uid), (UID_CAST)(*u));
631#endif
632 flag = 0;
633 break;
634 }
635 else
636 {
637#ifdef TRUST_DEBUG
638 fprintf (stderr,
639 "trustfile: uid=%ld, trusted_uid=%ld, no match\n",
640 (UID_CAST)(w->pw_uid), (UID_CAST)*u);
641#endif
642 ;
643 }
644 }
645 /* not found */
646 if (flag == -1)
647 {
648#ifdef TRUST_DEBUG
649 fprintf(stderr,"trustfile: group member %s not found in trusted users --> ERROR\n", w->pw_name);
650#endif
651 tf_baduid = w->pw_uid;
652 retval = SL_FALSE;
653 goto out;
654 /* SL_IRETURN(SL_FALSE, _("onlytrustedingrp")); */
655 }
656 }
657 }
658 retval = SL_TRUE;
659
660 out:
661
662#ifdef HAVE_ENDPWENT
663 sh_endpwent();
664#endif
665
666 SH_MUTEX_UNLOCK(mutex_pwent);
667
668 /* TEST_ONLY */
669#endif
670 /* #ifdef HAVE_GETPWENT */
671#endif
672
673#ifdef TRUST_DEBUG
674 if (retval == SL_TRUE)
675 fprintf(stderr,
676 "trustfile: group %ld: all members are trusted users --> OK\n",
677 (UID_CAST)grp);
678#endif
679 /* all found
680 */
681 SL_IRETURN(retval, _("onlytrustedingrp"));
682}
683
684int sl_trustfile(const char *fname, uid_t *okusers, uid_t *badusers)
685{
686 char fexp[MAXFILENAME]; /* file name fully expanded */
687 register char *p = fexp; /* used to hold name to be checked */
688 struct stat stbuf; /* used to check file permissions */
689 char c; /* used to hold temp char */
690
691 SL_ENTER(_("sl_trustfile"));
692 if (fname == NULL)
693 SL_IRETURN(SL_EBADFILE, _("sl_trustfile"));
694
695 /*
696 * next expand to the full file name
697 * getfname sets sl_errno as appropriate
698 */
699#ifdef TRUST_MAIN
700 sl_errno = getfname(fname, fexp, MAXFILENAME);
701 if (sl_errno != 0)
702 return sl_errno;
703#else
704 if (SL_ISERROR(getfname(fname, fexp, MAXFILENAME)))
705 SL_IRETURN(sl_errno, _("sl_trustfile"));
706#endif
707
708 if (okusers == NULL && badusers == NULL)
709 {
710 okusers = rootonly;
711 rootonly[EUIDSLOT] = tf_euid;
712 }
713
714 /*
715 * now loop through the path a component at a time
716 * note we have to special-case root
717 */
718 while(*p)
719 {
720 /*
721 * get next component
722 */
723 while(*p && *p != '/')
724 p++;
725
726 /* save where you are
727 */
728 if (p == fexp)
729 {
730 /* keep the / if it's the root dir
731 */
732 c = p[1];
733 p[1] = '\0';
734 }
735 else
736 {
737 /* clobber the / if it isn't the root dir
738 */
739 c = *p;
740 *p = '\0';
741 }
742
743 /*
744 * now get the information
745 */
746 if (retry_lstat(FIL__, __LINE__, fexp, &stbuf) < 0)
747 {
748 (void) strncpy(tf_path, fexp, sizeof(tf_path));
749 tf_path[sizeof(tf_path)-1] = '\0';
750#ifdef TRUST_MAIN
751 fprintf(stderr, "---------------------------------------------\n");
752 fprintf(stderr, "trustfile: ESTAT: stat(%s) failed,\n", fexp);
753 fprintf(stderr, "maybe the file does not exist\n");
754 fprintf(stderr, "---------------------------------------------\n");
755#endif
756 SL_IRETURN(SL_ESTAT, _("sl_trustfile"));
757 }
758
759#ifdef S_IFLNK
760 /*
761 * if it's a symbolic link, recurse
762 */
763 if ((stbuf.st_mode & S_IFLNK) == S_IFLNK)
764 {
765 /*
766 * this is tricky
767 * if the symlink is to an absolute path
768 * name, just call trustfile on it; but
769 * if it's a relative path name, it's
770 * interpreted WRT the current working
771 * directory AND NOT THE FILE NAME!!!!!
772 * so, we simply put /../ at the end of
773 * the file name, then append the symlink
774 * contents; trustfile will canonicalize
775 * this, and the /../ we added "undoes"
776 * the name of the symlink to put us in
777 * the current working directory, at
778 * which point the symlink contents (appended
779 * to the CWD) are interpreted correctly.
780 * got it?
781 */
782 char csym[MAXFILENAME]; /* contents of symlink file */
783 char full[MAXFILENAME]; /* "full" name of symlink */
784 register char *b, *t; /* used to copy stuff around */
785 register int lsym; /* num chars in symlink ref */
786 register int i; /* trustworthy or not? */
787 const char * t_const;
788 char *end;
789
790 /*
791 * get what the symbolic link points to
792 *
793 * The original code does not check the return code of readlink(),
794 * and has an off-by-one error
795 * (MAXFILENAME instead of MAXFILENAME-1)
796 * R.W. Tue May 29 22:05:16 CEST 2001
797 */
798 lsym = readlink(fexp, csym, MAXFILENAME-1);
799 if (lsym >= 0)
800 csym[lsym] = '\0';
801 else
802 {
803#ifdef TRUST_MAIN
804 fprintf(stderr, "---------------------------------------------\n");
805 fprintf(stderr, "trustfile: EBADNAME: readlink(%s) failed\n",
806 fexp);
807 fprintf(stderr, "---------------------------------------------\n");
808#endif
809 SL_IRETURN(SL_EBADNAME, _("sl_trustfile"));
810 }
811
812 /*
813 * relative or absolute referent?
814 */
815 if (csym[0] != '/')
816 {
817 /* pointer to one above last element
818 */
819 end = &full[MAXFILENAME-1]; ++end;
820
821 /* initialize pointers
822 */
823 b = full;
824
825 /* copy in base path
826 */
827 t = fexp;
828 while(*t && b < end)
829 *b++ = *t++;
830
831 /* smack on the /../
832 */
833 t_const = "/../"; t = (char *)t_const;
834 while(*t && b < end)
835 *b++ = *t++;
836
837 /* append the symlink referent
838 */
839 t = csym;
840 while(*t && b < end)
841 *b++ = *t++;
842
843 /* see if we're too big
844 */
845 if (*t || b == end)
846 {
847 /* yes -- error
848 */
849 (void) strncpy(tf_path, fexp, sizeof(tf_path));
850 tf_path[sizeof(tf_path)-1] = '\0';
851#ifdef TRUST_MAIN
852 fprintf(stderr, "---------------------------------------------\n");
853 fprintf(stderr,
854 "trustfile: ETRUNC: normalized path too long (%s)\n",
855 fexp);
856 fprintf(stderr, "---------------------------------------------\n");
857#endif
858 SL_IRETURN(SL_ETRUNC, _("sl_trustfile"));
859 }
860 *b = '\0';
861 }
862 else
863 {
864 /* absolute -- just copy */
865 /* overflow can't occur as the arrays */
866 /* are the same size */
867 (void) strcpy(full, csym); /* known to fit */
868 }
869 /*
870 * now check out this file and its ancestors
871 */
872 if ((i = sl_trustfile(full, okusers, badusers)) != SL_ENONE)
873 SL_IRETURN(i, _("sl_trustfile"));
874
875 /*
876 * okay, this part is valid ... let's check the rest
877 * put the / back
878 */
879 if (p == fexp)
880 {
881 /* special case for root */
882 p[1] = c;
883 p++;
884 }
885 else
886 {
887 /* ordinary case for everything else */
888 *p = c;
889 if (*p)
890 p++;
891 }
892 continue;
893 }
894#endif
895
896
897#ifdef TRUST_DEBUG
898 fprintf(stderr, "\ntrustfile: checking path=%s\n", fexp);
899#endif
900 /*
901 * if the owner is not trusted then -- as the owner can
902 * change protection modes -- he/she can write to the
903 * file regardless of permissions, so bomb
904 */
905 if (((okusers != NULL && SL_FALSE == isin((uid_t)stbuf.st_uid,okusers))||
906 (badusers != NULL && SL_TRUE == isin((uid_t)stbuf.st_uid,badusers))))
907 {
908#ifdef TRUST_DEBUG
909 fprintf(stderr, "---------------------------------------------\n");
910 fprintf(stderr, "trustfile: EBADUID %s (owner not trusted)\n",
911 fexp);
912 fprintf(stderr, "The owner of this file/directory is not in samhains\n");
913 fprintf(stderr, "list of trusted users.\n");
914 fprintf(stderr, "Please run ./configure again with the option\n");
915 fprintf(stderr, " ./configure [more options] --with-trusted=0,...,UID\n");
916 fprintf(stderr, "where UID is the UID of the (yet) untrusted user.\n");
917 fprintf(stderr, "---------------------------------------------\n");
918#endif
919 (void) strncpy(tf_path, fexp, sizeof(tf_path));
920 tf_path[sizeof(tf_path)-1] = '\0';
921
922 tf_baduid = (uid_t) stbuf.st_uid;
923 SL_IRETURN(SL_EBADUID, _("sl_trustfile"));
924 }
925
926 /*
927 * if a group member can write but the
928 * member is not trusted, bomb; but if
929 * sticky bit semantics are honored, it's
930 * okay
931 */
932 /* Thu Mar 29 21:10:28 CEST 2001 Rainer Wichmann
933 * replace !isingrp() with onlytrustedingrp(), as isingrp()
934 * will return at the first trusted user, even if there are additional
935 * (untrusted) users in the group
936 */
937 if (((stbuf.st_mode & S_IWGRP) == S_IWGRP) &&
938 ((okusers != NULL && !onlytrustedingrp((gid_t)stbuf.st_gid,okusers))||
939 (badusers != NULL && isingrp((gid_t)stbuf.st_gid, badusers)))
940#ifdef STICKY
941 && ((stbuf.st_mode&S_IFDIR) != S_IFDIR ||
942 (stbuf.st_mode&S_ISVTX) != S_ISVTX)
943#endif
944 )
945 {
946#ifdef TRUST_DEBUG
947 fprintf(stderr, "---------------------------------------------\n");
948 fprintf(stderr,
949 "trustfile: EBADGID %ld %s (group member not trusted)\n",
950 (UID_CAST)stbuf.st_gid, fexp);
951 fprintf(stderr, "This file/directory is group writeable, and one of the group members\n");
952 fprintf(stderr, "is not in samhains list of trusted users.\n");
953 fprintf(stderr, "Please run ./configure again with the option\n");
954 fprintf(stderr, " ./configure [more options] --with-trusted=0,...,UID\n");
955 fprintf(stderr, "where UID is the UID of the (yet) untrusted user.\n");
956 fprintf(stderr, "---------------------------------------------\n");
957#endif
958 (void) strncpy(tf_path, fexp, sizeof(tf_path));
959 tf_path[sizeof(tf_path)-1] = '\0';
960
961 tf_badgid = (gid_t) stbuf.st_gid;
962 SL_IRETURN(SL_EBADGID, _("sl_trustfile"));
963 }
964 /*
965 * if other can write, bomb; but if the sticky
966 * bit semantics are honored, it's okay
967 */
968 if (((stbuf.st_mode & S_IWOTH) == S_IWOTH)
969#ifdef STICKY
970 && ((stbuf.st_mode&S_IFDIR) != S_IFDIR ||
971 (stbuf.st_mode&S_ISVTX) != S_ISVTX)
972#endif
973 )
974 {
975#ifdef TRUST_DEBUG
976 fprintf(stderr, "---------------------------------------------\n");
977 fprintf(stderr, "trustfile: EBADOTH (world writeable): %s\n",
978 fexp);
979 fprintf(stderr, "This file/directory is world writeable.\n");
980 fprintf(stderr, "---------------------------------------------\n");
981#endif
982 (void) strncpy(tf_path, fexp, sizeof(tf_path));
983 tf_path[sizeof(tf_path)-1] = '\0';
984
985 SL_IRETURN(SL_EBADOTH, _("sl_trustfile"));
986 }
987 /*
988 * put the / back
989 */
990 if (p == fexp)
991 {
992 /* special case for root */
993 p[1] = c;
994 p++;
995 }
996 else
997 {
998 /* ordinary case for everything else */
999 *p = c;
1000 if (*p)
1001 p++;
1002 }
1003 }
1004 /*
1005 * yes, it can be trusted
1006 */
1007 (void) strncpy(tf_path, fexp, sizeof(tf_path));
1008 tf_path[sizeof(tf_path)-1] = '\0';
1009
1010 SL_IRETURN(SL_ENONE, _("sl_trustfile"));
1011}
1012
1013#ifdef TRUST_MAIN
1014
1015#if defined(HOST_IS_CYGWIN) || defined(__cygwin__) || defined(__CYGWIN32__) || defined(__CYGWIN__)
1016int main()
1017{
1018 return 0;
1019}
1020#else
1021int main (int argc, char * argv[])
1022{
1023 int status;
1024#if defined(SH_WITH_SERVER)
1025 struct passwd * pass;
1026#endif
1027
1028 if (argc < 2) {
1029 fprintf(stderr, "%s: Usage: %s <fullpath>\n", argv[0], argv[0]);
1030 return 1;
1031 }
1032
1033 tf_path[0] = '\0';
1034#if defined(SH_WITH_SERVER)
1035 pass = sh_getpwnam(SH_IDENT); /* TESTONLY */
1036 if (pass != NULL)
1037 tf_euid = pass->pw_uid;
1038 else
1039 {
1040 fprintf(stderr, "trustfile: ERROR: getpwnam(%s) failed\n",
1041 SH_IDENT);
1042 return 1;
1043 }
1044#else
1045 tf_euid = geteuid();
1046#endif
1047
1048 status = sl_trustfile(argv[1], NULL, NULL);
1049 if (status != SL_ENONE)
1050 {
1051 fprintf(stderr, "trustfile: ERROR: not a trusted path: %s\n",
1052 argv[1]);
1053 return 1;
1054 }
1055 return 0;
1056}
1057#endif
1058#endif
1059
1060
1061
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