source: trunk/src/trustfile.c@ 582

Last change on this file since 582 was 481, checked in by katerina, 9 years ago

Enhancements and fixes for tickets #374, #375, #376, #377, #378, and #379.
File size: 29.6 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#include <errno.h>
102
103
104#if !defined(TRUST_MAIN)
105
106#include "slib.h"
107#define SH_NEED_PWD_GRP 1
108#include "sh_static.h"
109#include "sh_pthread.h"
110
111#else
112
113#define sh_getgrgid getgrgid
114#define sh_getgrgid_r getgrgid_r
115#define sh_getpwnam getpwnam
116#define sh_getpwnam_r getpwnam_r
117#define sh_getpwuid getpwuid
118#define sh_getpwuid_r getpwuid_r
119#define sh_getpwent getpwent
120#define sh_endpwent endpwent
121
122#define TRUST_DEBUG
123#define S_FALSE 0
124#define S_TRUE 1
125#define SL_ENTER(string)
126#define SL_IRETURN(a, b) return a
127#define retry_lstat(a,b,c,d) lstat(c,d)
128#define _(string) string
129#define N_(string) string
130#define MAXFILENAME 4096
131static int sl_errno = 0;
132#define SL_ENONE 0
133#define SL_ENULL -1024 /* Invalid use of NULL pointer. */
134#define SL_ERANGE -1025 /* Argument out of range. */
135#define SL_ETRUNC -1026 /* Result truncated. */
136#define SL_EINTERNAL -1028 /* Internal error. */
137#define SL_EBADFILE -1030 /* File access error. Check errno. */
138#define SL_EMEM -1032 /* Out of memory. */
139#define SL_EBADNAME -1040 /* Invalid name. */
140#define SL_ESTAT -1041 /* stat of file failed. Check errno. */
141#define SL_EBADUID -1050 /* Owner not trustworthy. */
142#define SL_EBADGID -1051 /* Group writeable and not trustworthy.*/
143#define SL_EBADOTH -1052 /* World writeable. */
144
145#endif
146
147
148#if defined(__linux__) || defined(__FreeBSD__)
149#define STICKY
150#endif
151
152#undef FIL__
153#define FIL__ _("trustfile.c")
154
155/*
156 * the get current working directory function
157 * every version of UNIX seems to have its own
158 * idea of how to do this, so we group them by
159 * arguments ...
160 * all must return a pointer to the right name
161 */
162
163
164#ifndef TRUST_MAIN
165
166#if defined(HAVE_GETCWD) && !defined(HAVE_BROKEN_GETCWD)
167#define CURDIR(buf,nbuf) getcwd((buf), (nbuf))
168#elif defined(HAVE_GETWD)
169#define CURDIR(buf,nbuf) getwd((buf))
170#endif
171
172#else
173
174#define CURDIR(buf,nbuf) getcwd((buf), (nbuf))
175
176#endif
177
178
179
180/*
181 * this checks to see if there are symbolic links
182 * assumes the link bit in the protection mask is called S_IFLNK
183 * (seems to be true on all UNIXes with them)
184 */
185#ifndef S_IFLNK
186#define lstat stat
187#endif
188
189
190/*
191 * these are useful global variables
192 *
193 * first set: who you gonna trust, by default?
194 * if the user does not specify a trusted or untrusted set of users,
195 * all users are considered untrusted EXCEPT:
196 * UID 0 -- root as root can do anything on most UNIX systems, this
197 * seems reasonable
198 * tf_euid -- programmer-selectable UID
199 * if the caller specifies a specific UID by putting
200 * it in this variable, it will be trusted; this is
201 * typically used to trust the effective UID of the
202 * process (note: NOT the real UID, which will cause all
203 * sorts of problems!) By default, this is set to -1,
204 * so if it's not set, root is the only trusted user
205 */
206
207/* modified Tue Feb 22 10:36:44 NFT 2000 Rainer Wichmann */
208
209
210#ifndef SL_ALWAYS_TRUSTED
211#define SL_ALWAYS_TRUSTED 0
212#endif
213uid_t test_rootonly[] = { SL_ALWAYS_TRUSTED };
214
215#define tf_uid_neg ((uid_t)-1)
216
217uid_t rootonly[] = { SL_ALWAYS_TRUSTED,
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 tf_uid_neg, tf_uid_neg, tf_uid_neg, tf_uid_neg,
221 tf_uid_neg, tf_uid_neg, tf_uid_neg, tf_uid_neg };
222
223uid_t tf_euid = tf_uid_neg;
224unsigned int EUIDSLOT = sizeof(test_rootonly)/sizeof(uid_t);
225unsigned int ORIG_EUIDSLOT = sizeof(test_rootonly)/sizeof(uid_t);
226
227char tf_path[MAXFILENAME]; /* error path for trust function */
228uid_t tf_baduid;
229gid_t tf_badgid;
230
231static
232int dirz(char *path)
233{
234 register char *p = path;/* points to rest of path to clean up */
235 register char *q; /* temp pointer for skipping over stuff */
236
237 static char swp[MAXFILENAME];
238
239 SL_ENTER(_("dirz"));
240 /*
241 * standard error checking
242 */
243 if (path == NULL)
244 SL_IRETURN(SL_ENULL, _("dirz"));
245 if (path[0] == '.')
246 SL_IRETURN(SL_EINTERNAL, _("dirz"));
247
248
249 /*
250 * loop over the path name until everything is checked
251 */
252 while(*p)
253 {
254 /* skip
255 */
256 if (*p != '/')
257 {
258 p++;
259 continue;
260 }
261
262 /* "/./" or "/."
263 */
264 if (p[1] == '.' && (p[2] == '/' || p[2] == '\0'))
265 {
266 /* yes -- delete "/."
267 */
268 (void) strcpy(swp, &p[2]); /* known to fit */
269 (void) strcpy(p, swp); /* known to fit */
270
271 /* special case "/." as full path name
272 */
273 if (p == path && *p == '\0')
274 {
275 *p++ = '/';
276 *p = '\0';
277 }
278 }
279
280 /* "//"
281 */
282 else if (p[1] == '/')
283 {
284 /* yes -- skip
285 */
286 for(q = &p[2]; *q == '/'; q++)
287 ;
288 (void) strcpy(swp, q); /* known to fit */
289 (void) strcpy(&p[1], swp); /* known to fit */
290 }
291
292 /* "/../" or "/.."
293 */
294 else if (p[1] == '.' && p[2] == '.' && (p[3] == '/' || p[3] == '\0'))
295 {
296 /* yes -- if it's root, delete .. only
297 */
298 if (p == path)
299 {
300 (void) strcpy(swp, &p[3]); /* known to fit */
301 (void) strcpy(p, swp); /* known to fit */
302 }
303 else
304 {
305 /* back up over previous component
306 */
307 q = p - 1;
308 while(q != path && *q != '/')
309 q--;
310 /* now wipe it out
311 */
312 (void) strcpy(swp, &p[3]); /* known to fit */
313 (void) strcpy(q, swp); /* known to fit */
314 p = q;
315 }
316 }
317 else
318 p++;
319 }
320 SL_IRETURN(SL_ENONE, _("dirz"));
321}
322
323
324
325/* not static to circumvent stupid gcc 4 bug */
326int getfname(const char *fname, char *rbuf, int rsz)
327{
328#ifndef TRUST_MAIN
329 register int status;
330#endif
331
332 SL_ENTER(_("getfname"));
333 /*
334 * do the initial checking
335 * NULL pointer
336 */
337 if (fname == NULL || rbuf == NULL)
338 SL_IRETURN(SL_ENULL, _("getfname"));
339 if (rsz <= 0)
340 SL_IRETURN(SL_ERANGE, _("getfname"));
341
342
343 /* already a full path name */
344 if (*fname == '/')
345 rbuf[0] = '\0';
346 else
347 {
348 if (CURDIR(rbuf, rsz) == NULL)
349 {
350#ifdef TRUST_DEBUG
351 fprintf(stderr, "trustfile: getcwd failed\n");
352#endif
353 SL_IRETURN(SL_EBADNAME, _("getfname"));
354 }
355 }
356
357 /*
358 * append the file name and reduce
359 */
360 if (fname != NULL && *fname != '\0')
361 {
362#ifndef TRUST_MAIN
363 status = sl_strlcat(rbuf, "/", rsz);
364 if (status == SL_ENONE)
365 status = sl_strlcat(rbuf, fname, rsz);
366 if (status != SL_ENONE)
367 SL_IRETURN(status, _("getfname"));
368#else
369 strncat(rbuf, "/", rsz-strlen(rbuf)-1);
370 rbuf[rsz-1] = '\0';
371 strncat(rbuf, fname, rsz-strlen(rbuf)-1);
372 rbuf[rsz-1] = '\0';
373#endif
374 }
375 SL_IRETURN(dirz(rbuf), _("getfname"));
376}
377
378static
379int isin(uid_t n, uid_t *list)
380{
381 SL_ENTER(_("isin"));
382 if (list == NULL)
383 SL_IRETURN(S_FALSE, _("isin"));
384
385 while(*list != tf_uid_neg && *list != n)
386 {
387#ifdef TRUST_DEBUG
388 fprintf (stderr,
389 "trustfile: owner_uid=%ld, trusted uid=%ld, no match\n",
390 (UID_CAST) n, (UID_CAST) *list);
391#endif
392 list++;
393 }
394
395 if (*list == tf_uid_neg)
396 {
397#ifdef TRUST_DEBUG
398 fprintf (stderr,
399 "trustfile: owner_uid=%ld, no match with any trusted user --> ERROR\n",
400 (UID_CAST) n);
401#endif
402 SL_IRETURN(S_FALSE, _("isin"));
403 }
404
405#ifdef TRUST_DEBUG
406 fprintf (stderr,
407 "trustfile: owner_uid=%ld, trusted_uid=%ld, match found --> OK\n",
408 (UID_CAST)n, (UID_CAST)*list);
409#endif
410 SL_IRETURN(S_TRUE, _("isin"));
411}
412
413/* comment added by R. Wichmann
414 * RETURN TRUE if ANYONE in ulist is group member
415 */
416/* not static to circumvent stupid gcc 4 bug */
417int isingrp(gid_t grp, uid_t *ulist, int * errval)
418{
419 struct passwd *w; /* info about group member */
420 register uid_t *u; /* points to current ulist member */
421 register char **p; /* points to current group member */
422 struct group *g; /* pointer to group information */
423
424 int status;
425
426#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
427 struct group gr;
428 char * buffer = NULL;
429 struct passwd pwd;
430 char * pbuffer = NULL;
431#endif
432
433 SL_ENTER(_("isingrp"));
434
435 *errval = 0;
436
437#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
438 buffer = calloc(1,SH_GRBUF_SIZE);
439 status = sh_getgrgid_r(grp, &gr, buffer, SH_GRBUF_SIZE, &g);
440#else
441 errno = 0;
442 g = sh_getgrgid(grp);
443 status = errno;
444#endif
445
446 if (g == NULL)
447 {
448 if (status == ERANGE)
449 *errval = status;
450
451 goto end_false;
452 }
453
454 /* this will return at the first match
455 */
456#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
457 pbuffer = calloc(1,SH_PWBUF_SIZE);
458#endif
459
460 for(p = g->gr_mem; *p != NULL; p++)
461 {
462 for(u = ulist; *u != tf_uid_neg; u++)
463 {
464 /* map user name to UID and compare */
465#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETPWNAM_R)
466 sh_getpwnam_r(*p, &pwd, pbuffer, SH_PWBUF_SIZE, &w);
467#else
468 w = sh_getpwnam(*p);
469#endif
470
471#ifdef TRUST_MAIN
472 if (w != NULL && *u == (uid_t)(w->pw_uid) )
473 goto end_true;
474#else
475 if (w != NULL && *u == (uid_t)(w->pw_uid) )
476 {
477 goto end_true;
478 }
479#endif
480 }
481 }
482 /* added by R. Wichmann Fri Mar 30 08:16:14 CEST 2001:
483 * a user can have a GID but no entry in /etc/group
484 */
485 for(u = ulist; *u != tf_uid_neg; u++)
486 {
487#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETPWUID_R)
488 sh_getpwuid_r(*u, &pwd, pbuffer, SH_PWBUF_SIZE, &w);
489#else
490 w = sh_getpwuid(*u);
491#endif
492#ifdef TRUST_MAIN
493 if (w != NULL && grp == (gid_t)(w->pw_gid) )
494 goto end_true;
495#else
496 if (w != NULL && grp == (gid_t)(w->pw_gid) )
497 {
498 goto end_true;
499 }
500#endif
501 }
502
503 end_false:
504#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
505 if (buffer) free(buffer);
506 if (pbuffer) free(pbuffer);
507#endif
508 SL_IRETURN(S_FALSE, _("isingrp"));
509
510 end_true:
511#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
512 if (buffer) free(buffer);
513 if (pbuffer) free(pbuffer);
514#endif
515 SL_IRETURN(S_TRUE, _("isingrp"));
516}
517
518/* added by R. Wichmann Fri Mar 30 08:16:14 CEST 2001
519 * RETURN TRUE only if ALL group members are trusted
520 */
521/* not static to circumvent stupid gcc 4 bug */
522int onlytrustedingrp(gid_t grp, uid_t *ulist, int * errval)
523{
524 struct passwd *w; /* info about group member */
525 register uid_t *u; /* points to current ulist member */
526 register char **p; /* points to current group member */
527 struct group *g; /* pointer to group information */
528 register int flag = -1; /* group member found */
529
530 int status;
531
532#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
533 struct group gr;
534 char * buffer = NULL;
535 struct passwd pw;
536 char * pbuffer = NULL;
537#endif
538
539 int retval = S_FALSE;
540
541 SL_ENTER(_("onlytrustedingrp"));
542
543 *errval = 0;
544
545#ifdef TRUST_DEBUG
546 fprintf(stderr, "trustfile: group writeable, group_gid: %ld\n",
547 (UID_CAST)grp);
548#endif
549
550#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
551 buffer = calloc(1,SH_GRBUF_SIZE);
552 status = sh_getgrgid_r(grp, &gr, buffer, SH_GRBUF_SIZE, &g);
553#else
554 errno = 0;
555 g = sh_getgrgid(grp);
556 status = errno;
557#endif
558
559 if (g == NULL)
560 {
561 if (status == ERANGE)
562 *errval = status;
563
564#ifdef TRUST_DEBUG
565 fprintf(stderr,
566 "trustfile: group_gid: %ld, no such group --> ERROR\n",
567 (UID_CAST)grp);
568#endif
569 retval = S_FALSE;
570 goto end_retval;
571 }
572
573 /* empty group -> no problem
574
575 if(g->gr_mem == NULL || g->gr_mem[0] == NULL )
576 SL_IRETURN(S_TRUE, _("onlytrustedingrp") );
577 */
578
579 /* check for untrusted members of the group
580 */
581#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETPWNAM_R)
582 pbuffer = calloc(1,SH_PWBUF_SIZE);
583#endif
584
585 for(p = g->gr_mem; *p != NULL; p++)
586 {
587 flag = -1;
588#ifdef TRUST_DEBUG
589 fprintf(stderr, "trustfile: group_member: %s\n", *p);
590#endif
591 /* map user name to UID and compare
592 */
593#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETPWNAM_R)
594 sh_getpwnam_r(*p, &pw, pbuffer, SH_PWBUF_SIZE, &w);
595#else
596 w = sh_getpwnam(*p);
597#endif
598
599 if (w == NULL) /* not a valid user, ignore */
600 {
601 flag = 0;
602 }
603 else /* check list of trusted users */
604 {
605#ifdef TRUST_DEBUG
606 fprintf (stderr,
607 "trustfile: uid=%ld, checking whether it is trusted\n",
608 (UID_CAST)(w->pw_uid));
609#endif
610 for(u = ulist; *u != tf_uid_neg; u++)
611 {
612 if (*u == (w->pw_uid) )
613 {
614#ifdef TRUST_DEBUG
615 fprintf (stderr,
616 "trustfile: uid=%ld, trusted_uid=%ld, match found --> OK\n",
617 (UID_CAST)(w->pw_uid), (UID_CAST)*u);
618#endif
619 flag = 0;
620 break;
621 }
622 else
623 {
624#ifdef TRUST_DEBUG
625 fprintf (stderr,
626 "trustfile: uid=%ld, trusted_uid=%ld, no match\n",
627 (UID_CAST)(w->pw_uid), (UID_CAST)*u);
628#endif
629 ;
630 }
631 }
632 }
633 /* not found
634 */
635 if (flag == -1)
636 {
637#ifdef TRUST_DEBUG
638 fprintf (stderr,
639 "trustfile: user=%s (gid %ld), not a trusted user --> ERROR\n", *p, (UID_CAST)grp);
640#endif
641 tf_baduid = w->pw_uid;
642 retval = S_FALSE;
643#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
644 if (pbuffer) free(pbuffer);
645#endif
646 goto end_retval;
647 }
648 }
649
650#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
651 if (pbuffer) free(pbuffer);
652#endif
653
654#ifndef TEST_ONLY
655#ifdef HAVE_GETPWENT
656 /* now check ALL users for their GID !!!
657 */
658 SH_MUTEX_LOCK(mutex_pwent);
659
660 while (NULL != (w = sh_getpwent()))
661 {
662 if (grp == (gid_t)(w->pw_gid))
663 {
664#ifdef TRUST_DEBUG
665 fprintf(stderr, "trustfile: checking group member %s, uid %ld\n",
666 w->pw_name, (UID_CAST)w->pw_uid);
667#endif
668 /* is it a trusted user ?
669 */
670 flag = -1;
671 for(u = ulist; *u != tf_uid_neg; u++)
672 {
673 if (*u == (uid_t)(w->pw_uid))
674 {
675#ifdef TRUST_DEBUG
676 fprintf (stderr,
677 "trustfile: uid=%ld, trusted_uid=%ld, match found --> OK\n",
678 (UID_CAST)(w->pw_uid), (UID_CAST)(*u));
679#endif
680 flag = 0;
681 break;
682 }
683 else
684 {
685#ifdef TRUST_DEBUG
686 fprintf (stderr,
687 "trustfile: uid=%ld, trusted_uid=%ld, no match\n",
688 (UID_CAST)(w->pw_uid), (UID_CAST)*u);
689#endif
690 ;
691 }
692 }
693 /* not found */
694 if (flag == -1)
695 {
696#ifdef TRUST_DEBUG
697 fprintf(stderr,"trustfile: group member %s not found in trusted users --> ERROR\n", w->pw_name);
698#endif
699 tf_baduid = w->pw_uid;
700 retval = S_FALSE;
701 goto out;
702 /* SL_IRETURN(S_FALSE, _("onlytrustedingrp")); */
703 }
704 }
705 }
706 retval = S_TRUE;
707
708 out:
709
710#ifdef HAVE_ENDPWENT
711 sh_endpwent();
712#endif
713
714 SH_MUTEX_UNLOCK(mutex_pwent);
715
716 /* TEST_ONLY */
717#endif
718 /* #ifdef HAVE_GETPWENT */
719#endif
720
721#ifdef TRUST_DEBUG
722 if (retval == S_TRUE)
723 fprintf(stderr,
724 "trustfile: group %ld: all members are trusted users --> OK\n",
725 (UID_CAST)grp);
726#endif
727 /* all found
728 */
729 end_retval:
730#if defined(HAVE_PTHREAD) && defined (_POSIX_THREAD_SAFE_FUNCTIONS) && defined(HAVE_GETGRGID_R)
731 if (buffer) free(buffer);
732#endif
733 SL_IRETURN(retval, _("onlytrustedingrp"));
734}
735
736int sl_trustfile(const char *fname, uid_t *okusers, uid_t *badusers)
737{
738 char * fexp = NULL; /* file name fully expanded */
739 register char *p; /* used to hold name to be checked */
740 struct stat stbuf; /* used to check file permissions */
741 char c; /* used to hold temp char */
742
743 int errgrp = 0;
744
745 SL_ENTER(_("sl_trustfile"));
746 if (fname == NULL)
747 SL_IRETURN(SL_EBADFILE, _("sl_trustfile"));
748
749 fexp = calloc(1, MAXFILENAME );
750 if (!fexp)
751 SL_IRETURN(SL_EMEM, _("sl_trustfile"));
752
753 p = fexp;
754
755 /*
756 * next expand to the full file name
757 * getfname sets sl_errno as appropriate
758 */
759#ifdef TRUST_MAIN
760 sl_errno = getfname(fname, fexp, MAXFILENAME);
761 if (sl_errno != 0)
762 {
763 free(fexp);
764 return sl_errno;
765 }
766#else
767 if (SL_ISERROR(getfname(fname, fexp, MAXFILENAME)))
768 {
769 free(fexp);
770 SL_IRETURN(sl_errno, _("sl_trustfile"));
771 }
772#endif
773
774 if (okusers == NULL && badusers == NULL)
775 {
776 okusers = rootonly;
777 rootonly[EUIDSLOT] = tf_euid;
778 }
779
780 /*
781 * now loop through the path a component at a time
782 * note we have to special-case root
783 */
784 while(*p)
785 {
786 /*
787 * get next component
788 */
789 while(*p && *p != '/')
790 p++;
791
792 /* save where you are
793 */
794 if (p == fexp)
795 {
796 /* keep the / if it's the root dir
797 */
798 c = p[1];
799 p[1] = '\0';
800 }
801 else
802 {
803 /* clobber the / if it isn't the root dir
804 */
805 c = *p;
806 *p = '\0';
807 }
808
809 /*
810 * now get the information
811 */
812 if (retry_lstat(FIL__, __LINE__, fexp, &stbuf) < 0)
813 {
814 (void) strncpy(tf_path, fexp, sizeof(tf_path));
815 tf_path[sizeof(tf_path)-1] = '\0';
816#ifdef TRUST_MAIN
817 fprintf(stderr, "---------------------------------------------\n");
818 fprintf(stderr, "trustfile: ESTAT: stat(%s) failed,\n", fexp);
819 fprintf(stderr, "maybe the file does not exist\n");
820 fprintf(stderr, "---------------------------------------------\n");
821#endif
822 free(fexp);
823 SL_IRETURN(SL_ESTAT, _("sl_trustfile"));
824 }
825
826#ifdef S_IFLNK
827 /*
828 * if it's a symbolic link, recurse
829 */
830 if ((stbuf.st_mode & S_IFLNK) == S_IFLNK)
831 {
832 /*
833 * this is tricky
834 * if the symlink is to an absolute path
835 * name, just call trustfile on it; but
836 * if it's a relative path name, it's
837 * interpreted WRT the current working
838 * directory AND NOT THE FILE NAME!!!!!
839 * so, we simply put /../ at the end of
840 * the file name, then append the symlink
841 * contents; trustfile will canonicalize
842 * this, and the /../ we added "undoes"
843 * the name of the symlink to put us in
844 * the current working directory, at
845 * which point the symlink contents (appended
846 * to the CWD) are interpreted correctly.
847 * got it?
848 */
849 char * csym; /* contents of symlink file */
850 char * full; /* "full" name of symlink */
851 char *b; /* used to copy stuff around */
852 const char *t; /* used to copy stuff around */
853 int lsym; /* num chars in symlink ref */
854 int i; /* trustworthy or not? */
855 const char * t_const;
856 char *end;
857
858 /*
859 * get what the symbolic link points to
860 *
861 * The original code does not check the return code of readlink(),
862 * and has an off-by-one error
863 * (MAXFILENAME instead of MAXFILENAME-1)
864 * R.W. Tue May 29 22:05:16 CEST 2001
865 */
866 csym = calloc(1, MAXFILENAME );
867 if (!csym)
868 {
869 free(fexp);
870 SL_IRETURN(SL_EMEM, _("sl_trustfile"));
871 }
872
873 lsym = readlink(fexp, csym, MAXFILENAME-1);
874 if (lsym >= 0)
875 csym[lsym] = '\0';
876 else
877 {
878#ifdef TRUST_MAIN
879 fprintf(stderr, "---------------------------------------------\n");
880 fprintf(stderr, "trustfile: EBADNAME: readlink(%s) failed\n",
881 fexp);
882 fprintf(stderr, "---------------------------------------------\n");
883#endif
884 free(csym);
885 free(fexp);
886 SL_IRETURN(SL_EBADNAME, _("sl_trustfile"));
887 }
888
889 full = calloc(1, MAXFILENAME );
890 if (!full)
891 {
892 free(csym);
893 free(fexp);
894 SL_IRETURN(SL_EMEM, _("sl_trustfile"));
895 }
896
897 /*
898 * relative or absolute referent?
899 */
900 if (csym[0] != '/')
901 {
902 /* pointer to one above last element
903 */
904 end = &full[MAXFILENAME-1]; ++end;
905
906 /* initialize pointers
907 */
908 b = full;
909
910 /* copy in base path
911 */
912 t = fexp;
913 while(*t && b < end)
914 *b++ = *t++;
915
916 /* smack on the /../
917 */
918 t_const = "/../"; t = (const char *)t_const;
919 while(*t && b < end)
920 *b++ = *t++;
921
922 /* append the symlink referent
923 */
924 t = csym;
925 while(*t && b < end)
926 *b++ = *t++;
927
928 /* see if we're too big
929 */
930 if (*t || b == end)
931 {
932 /* yes -- error
933 */
934 (void) strncpy(tf_path, fexp, sizeof(tf_path));
935 tf_path[sizeof(tf_path)-1] = '\0';
936#ifdef TRUST_MAIN
937 fprintf(stderr, "---------------------------------------------\n");
938 fprintf(stderr,
939 "trustfile: ETRUNC: normalized path too long (%s)\n",
940 fexp);
941 fprintf(stderr, "---------------------------------------------\n");
942#endif
943 free(full);
944 free(csym);
945 free(fexp);
946 SL_IRETURN(SL_ETRUNC, _("sl_trustfile"));
947 }
948 *b = '\0';
949 }
950 else
951 {
952 /* absolute -- just copy */
953 /* overflow can't occur as the arrays */
954 /* are the same size */
955 (void) strcpy(full, csym); /* known to fit */
956 }
957 /*
958 * now check out this file and its ancestors
959 */
960 if ((i = sl_trustfile(full, okusers, badusers)) != SL_ENONE)
961 {
962 free(full);
963 free(csym);
964 free(fexp);
965 SL_IRETURN(i, _("sl_trustfile"));
966 }
967
968 /*
969 * okay, this part is valid ... let's check the rest
970 * put the / back
971 */
972 if (p == fexp)
973 {
974 /* special case for root */
975 p[1] = c;
976 p++;
977 }
978 else
979 {
980 /* ordinary case for everything else */
981 *p = c;
982 if (*p)
983 p++;
984 }
985 free(full);
986 free(csym);
987 continue;
988 }
989#endif
990
991
992#ifdef TRUST_DEBUG
993 fprintf(stderr, "\ntrustfile: checking path=%s\n", fexp);
994#endif
995 /*
996 * if the owner is not trusted then -- as the owner can
997 * change protection modes -- he/she can write to the
998 * file regardless of permissions, so bomb
999 */
1000 if (((okusers != NULL && S_FALSE == isin((uid_t)stbuf.st_uid,okusers))||
1001 (badusers != NULL && S_TRUE == isin((uid_t)stbuf.st_uid,badusers))))
1002 {
1003#ifdef TRUST_DEBUG
1004 fprintf(stderr, "---------------------------------------------\n");
1005 fprintf(stderr, "trustfile: EBADUID %s (owner not trusted)\n",
1006 fexp);
1007 fprintf(stderr, "The owner of this file/directory is not in samhains\n");
1008 fprintf(stderr, "list of trusted users.\n");
1009 fprintf(stderr, "Please run ./configure again with the option\n");
1010 fprintf(stderr, " ./configure [more options] --with-trusted=0,...,UID\n");
1011 fprintf(stderr, "where UID is the UID of the (yet) untrusted user.\n");
1012 fprintf(stderr, "---------------------------------------------\n");
1013#endif
1014 (void) strncpy(tf_path, fexp, sizeof(tf_path));
1015 tf_path[sizeof(tf_path)-1] = '\0';
1016
1017 tf_baduid = (uid_t) stbuf.st_uid;
1018 free(fexp);
1019 SL_IRETURN(SL_EBADUID, _("sl_trustfile"));
1020 }
1021
1022 /*
1023 * if a group member can write but the
1024 * member is not trusted, bomb; but if
1025 * sticky bit semantics are honored, it's
1026 * okay
1027 */
1028 /* Thu Mar 29 21:10:28 CEST 2001 Rainer Wichmann
1029 * replace !isingrp() with onlytrustedingrp(), as isingrp()
1030 * will return at the first trusted user, even if there are additional
1031 * (untrusted) users in the group
1032 */
1033 if (((stbuf.st_mode & S_IWGRP) == S_IWGRP) &&
1034 ((okusers != NULL && !onlytrustedingrp((gid_t)stbuf.st_gid,okusers,&errgrp))||
1035 (badusers != NULL && isingrp((gid_t)stbuf.st_gid, badusers,&errgrp)))
1036#ifdef STICKY
1037 && ((stbuf.st_mode&S_IFDIR) != S_IFDIR ||
1038 (stbuf.st_mode&S_ISVTX) != S_ISVTX)
1039#endif
1040 )
1041 {
1042#ifdef TRUST_DEBUG
1043 fprintf(stderr, "---------------------------------------------\n");
1044 fprintf(stderr,
1045 "trustfile: EBADGID %ld %s (group member not trusted)\n",
1046 (UID_CAST)stbuf.st_gid, fexp);
1047 fprintf(stderr, "This file/directory is group writeable, and one of the group members\n");
1048 fprintf(stderr, "is not in samhains list of trusted users.\n");
1049 fprintf(stderr, "Please run ./configure again with the option\n");
1050 fprintf(stderr, " ./configure [more options] --with-trusted=0,...,UID\n");
1051 fprintf(stderr, "where UID is the UID of the (yet) untrusted user.\n");
1052 fprintf(stderr, "---------------------------------------------\n");
1053#endif
1054 (void) strncpy(tf_path, fexp, sizeof(tf_path));
1055 tf_path[sizeof(tf_path)-1] = '\0';
1056
1057 tf_badgid = (gid_t) stbuf.st_gid;
1058 free(fexp);
1059 SL_IRETURN((errgrp == ERANGE) ? SL_ERANGE : SL_EBADGID, _("sl_trustfile"));
1060 }
1061 /*
1062 * if other can write, bomb; but if the sticky
1063 * bit semantics are honored, it's okay
1064 */
1065 if (((stbuf.st_mode & S_IWOTH) == S_IWOTH)
1066#ifdef STICKY
1067 && ((stbuf.st_mode&S_IFDIR) != S_IFDIR ||
1068 (stbuf.st_mode&S_ISVTX) != S_ISVTX)
1069#endif
1070 )
1071 {
1072#ifdef TRUST_DEBUG
1073 fprintf(stderr, "---------------------------------------------\n");
1074 fprintf(stderr, "trustfile: EBADOTH (world writeable): %s\n",
1075 fexp);
1076 fprintf(stderr, "This file/directory is world writeable.\n");
1077 fprintf(stderr, "---------------------------------------------\n");
1078#endif
1079 (void) strncpy(tf_path, fexp, sizeof(tf_path));
1080 tf_path[sizeof(tf_path)-1] = '\0';
1081
1082 free(fexp);
1083 SL_IRETURN(SL_EBADOTH, _("sl_trustfile"));
1084 }
1085 /*
1086 * put the / back
1087 */
1088 if (p == fexp)
1089 {
1090 /* special case for root */
1091 p[1] = c;
1092 p++;
1093 }
1094 else
1095 {
1096 /* ordinary case for everything else */
1097 *p = c;
1098 if (*p)
1099 p++;
1100 }
1101 }
1102 /*
1103 * yes, it can be trusted
1104 */
1105 (void) strncpy(tf_path, fexp, sizeof(tf_path));
1106 tf_path[sizeof(tf_path)-1] = '\0';
1107
1108 free(fexp);
1109 SL_IRETURN(SL_ENONE, _("sl_trustfile"));
1110}
1111
1112#ifdef TRUST_MAIN
1113
1114#if defined(HOST_IS_CYGWIN) || defined(__cygwin__) || defined(__CYGWIN32__) || defined(__CYGWIN__)
1115int main()
1116{
1117 return 0;
1118}
1119#else
1120int main (int argc, char * argv[])
1121{
1122 int status;
1123#if defined(SH_WITH_SERVER)
1124 struct passwd * pass;
1125#endif
1126
1127 if (argc < 2) {
1128 fprintf(stderr, "%s: Usage: %s <fullpath>\n", argv[0], argv[0]);
1129 return 1;
1130 }
1131
1132 tf_path[0] = '\0';
1133#if defined(SH_WITH_SERVER)
1134 pass = sh_getpwnam(SH_IDENT); /* TESTONLY */
1135 if (pass != NULL)
1136 tf_euid = pass->pw_uid;
1137 else
1138 {
1139 fprintf(stderr, "trustfile: ERROR: getpwnam(%s) failed\n",
1140 SH_IDENT);
1141 return 1;
1142 }
1143#else
1144 tf_euid = geteuid();
1145#endif
1146
1147 status = sl_trustfile(argv[1], NULL, NULL);
1148 if (status != SL_ENONE)
1149 {
1150 fprintf(stderr, "trustfile: ERROR: not a trusted path: %s\n",
1151 argv[1]);
1152 return 1;
1153 }
1154 return 0;
1155}
1156#endif
1157#endif
1158
1159
1160
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