login_cap.c revision 121530 
1/*-
2 * Copyright (c) 1996 by
3 * Sean Eric Fagan <sef@kithrup.com>
4 * David Nugent <davidn@blaze.net.au>
5 * All rights reserved.
6 *
7 * Portions copyright (c) 1995,1997
8 * Berkeley Software Design, Inc.
9 * All rights reserved.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, is permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice immediately at the beginning of the file, without modification,
16 *    this list of conditions, and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in the
19 *    documentation and/or other materials provided with the distribution.
20 * 3. This work was done expressly for inclusion into FreeBSD.  Other use
21 *    is permitted provided this notation is included.
22 * 4. Absolutely no warranty of function or purpose is made by the authors.
23 * 5. Modifications may be freely made to this file providing the above
24 *    conditions are met.
25 *
26 * Low-level routines relating to the user capabilities database
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD: head/lib/libutil/login_cap.c 121530 2003-10-26 03:51:47Z peter $");
31
32#include <sys/types.h>
33#include <sys/time.h>
34#include <sys/resource.h>
35#include <sys/param.h>
36#include <errno.h>
37#include <fcntl.h>
38#include <libutil.h>
39#include <login_cap.h>
40#include <pwd.h>
41#include <stdio.h>
42#include <stdlib.h>
43#include <string.h>
44#include <syslog.h>
45#include <unistd.h>
46
47/*
48 * allocstr()
49 * Manage a single static pointer for handling a local char* buffer,
50 * resizing as necessary to contain the string.
51 *
52 * allocarray()
53 * Manage a static array for handling a group of strings, resizing
54 * when necessary.
55 */
56
57static int lc_object_count = 0;
58
59static size_t internal_stringsz = 0;
60static char * internal_string = NULL;
61static size_t internal_arraysz = 0;
62static const char ** internal_array = NULL;
63
64static char *
65allocstr(const char *str)
66{
67    char    *p;
68
69    size_t sz = strlen(str) + 1;	/* realloc() only if necessary */
70    if (sz <= internal_stringsz)
71	p = strcpy(internal_string, str);
72    else if ((p = realloc(internal_string, sz)) != NULL) {
73	internal_stringsz = sz;
74	internal_string = strcpy(p, str);
75    }
76    return p;
77}
78
79
80static const char **
81allocarray(size_t sz)
82{
83    static const char    **p;
84
85    if (sz <= internal_arraysz)
86	p = internal_array;
87    else if ((p = realloc(internal_array, sz * sizeof(char*))) != NULL) {
88	internal_arraysz = sz;
89	internal_array = p;
90    }
91    return p;
92}
93
94
95/*
96 * arrayize()
97 * Turn a simple string <str> separated by any of
98 * the set of <chars> into an array.  The last element
99 * of the array will be NULL, as is proper.
100 * Free using freearraystr()
101 */
102
103static const char **
104arrayize(const char *str, const char *chars, int *size)
105{
106    int	    i;
107    char *ptr;
108    const char *cptr;
109    const char **res = NULL;
110
111    /* count the sub-strings */
112    for (i = 0, cptr = str; *cptr; i++) {
113	int count = strcspn(cptr, chars);
114	cptr += count;
115	if (*cptr)
116	    ++cptr;
117    }
118
119    /* alloc the array */
120    if ((ptr = allocstr(str)) != NULL) {
121	if ((res = allocarray(++i)) == NULL)
122	    free((void *)(uintptr_t)(const void *)str);
123	else {
124	    /* now split the string */
125	    i = 0;
126	    while (*ptr) {
127		int count = strcspn(ptr, chars);
128		res[i++] = ptr;
129		ptr += count;
130		if (*ptr)
131		    *ptr++ = '\0';
132	    }
133	    res[i] = NULL;
134	}
135    }
136
137    if (size)
138	*size = i;
139
140    return res;
141}
142
143
144/*
145 * login_close()
146 * Frees up all resources relating to a login class
147 *
148 */
149
150void
151login_close(login_cap_t * lc)
152{
153    if (lc) {
154	free(lc->lc_style);
155	free(lc->lc_class);
156	free(lc->lc_cap);
157	free(lc);
158	if (--lc_object_count == 0) {
159	    free(internal_string);
160	    free(internal_array);
161	    internal_array = NULL;
162	    internal_arraysz = 0;
163	    internal_string = NULL;
164	    internal_stringsz = 0;
165	    cgetclose();
166	}
167    }
168}
169
170
171/*
172 * login_getclassbyname() get the login class by its name.
173 * If the name given is NULL or empty, the default class
174 * LOGIN_DEFCLASS (ie. "default") is fetched. If the
175 * 'dir' argument contains a non-NULL non-empty string,
176 * then the file _FILE_LOGIN_CONF is picked up from that
177 * directory instead of the system login database.
178 * Return a filled-out login_cap_t structure, including
179 * class name, and the capability record buffer.
180 */
181
182login_cap_t *
183login_getclassbyname(char const *name, const struct passwd *pwd)
184{
185    login_cap_t	*lc;
186
187    if ((lc = malloc(sizeof(login_cap_t))) != NULL) {
188	int         r, me, i = 0;
189	uid_t euid = 0;
190	gid_t egid = 0;
191	const char  *msg = NULL;
192	const char  *dir;
193	char	    userpath[MAXPATHLEN];
194
195	static char *login_dbarray[] = { NULL, NULL, NULL };
196
197	me = (name != NULL && strcmp(name, LOGIN_MECLASS) == 0);
198	dir = (!me || pwd == NULL) ? NULL : pwd->pw_dir;
199	/*
200	 * Switch to user mode before checking/reading its ~/.login_conf
201	 * - some NFSes have root read access disabled.
202	 *
203	 * XXX: This fails to configure additional groups.
204	 */
205	if (dir) {
206	    euid = geteuid();
207	    egid = getegid();
208	    (void)setegid(pwd->pw_gid);
209	    (void)seteuid(pwd->pw_uid);
210	}
211
212	if (dir && snprintf(userpath, MAXPATHLEN, "%s/%s", dir,
213			    _FILE_LOGIN_CONF) < MAXPATHLEN) {
214	    login_dbarray[i] = userpath;
215	    if (_secure_path(userpath, pwd->pw_uid, pwd->pw_gid) != -1)
216		i++;		/* only use 'secure' data */
217	}
218	if (_secure_path(_PATH_LOGIN_CONF, 0, 0) != -1)
219	    login_dbarray[i++] = _PATH_LOGIN_CONF;
220	login_dbarray[i] = NULL;
221
222	memset(lc, 0, sizeof(login_cap_t));
223	lc->lc_cap = lc->lc_class = lc->lc_style = NULL;
224
225	if (name == NULL || *name == '\0')
226	    name = LOGIN_DEFCLASS;
227
228	switch (cgetent(&lc->lc_cap, login_dbarray, name)) {
229	case -1:		/* Failed, entry does not exist */
230	    if (me)
231		break;	/* Don't retry default on 'me' */
232	    if (i == 0)
233	        r = -1;
234	    else if ((r = open(login_dbarray[0], O_RDONLY)) >= 0)
235	        close(r);
236	    /*
237	     * If there's at least one login class database,
238	     * and we aren't searching for a default class
239	     * then complain about a non-existent class.
240	     */
241	    if (r >= 0 || strcmp(name, LOGIN_DEFCLASS) != 0)
242		syslog(LOG_ERR, "login_getclass: unknown class '%s'", name);
243	    /* fall-back to default class */
244	    name = LOGIN_DEFCLASS;
245	    msg = "%s: no default/fallback class '%s'";
246	    if (cgetent(&lc->lc_cap, login_dbarray, name) != 0 && r >= 0)
247		break;
248	    /* FALLTHROUGH - just return system defaults */
249	case 0:		/* success! */
250	    if ((lc->lc_class = strdup(name)) != NULL) {
251		if (dir) {
252		    (void)seteuid(euid);
253		    (void)setegid(egid);
254		}
255		++lc_object_count;
256		return lc;
257	    }
258	    msg = "%s: strdup: %m";
259	    break;
260	case -2:
261	    msg = "%s: retrieving class information: %m";
262	    break;
263	case -3:
264	    msg = "%s: 'tc=' reference loop '%s'";
265	    break;
266	case 1:
267	    msg = "couldn't resolve 'tc=' reference in '%s'";
268	    break;
269	default:
270	    msg = "%s: unexpected cgetent() error '%s': %m";
271	    break;
272	}
273	if (dir) {
274	    (void)seteuid(euid);
275	    (void)setegid(egid);
276	}
277	if (msg != NULL)
278	    syslog(LOG_ERR, msg, "login_getclass", name);
279	free(lc);
280    }
281
282    return NULL;
283}
284
285
286
287/*
288 * login_getclass()
289 * Get the login class for the system (only) login class database.
290 * Return a filled-out login_cap_t structure, including
291 * class name, and the capability record buffer.
292 */
293
294login_cap_t *
295login_getclass(const char *cls)
296{
297    return login_getclassbyname(cls, NULL);
298}
299
300
301/*
302 * login_getclass()
303 * Get the login class for a given password entry from
304 * the system (only) login class database.
305 * If the password entry's class field is not set, or
306 * the class specified does not exist, then use the
307 * default of LOGIN_DEFCLASS (ie. "default").
308 * Return a filled-out login_cap_t structure, including
309 * class name, and the capability record buffer.
310 */
311
312login_cap_t *
313login_getpwclass(const struct passwd *pwd)
314{
315    const char	*cls = NULL;
316
317    if (pwd != NULL) {
318	cls = pwd->pw_class;
319	if (cls == NULL || *cls == '\0')
320	    cls = (pwd->pw_uid == 0) ? LOGIN_DEFROOTCLASS : LOGIN_DEFCLASS;
321    }
322    return login_getclassbyname(cls, pwd);
323}
324
325
326/*
327 * login_getuserclass()
328 * Get the login class for a given password entry, allowing user
329 * overrides via ~/.login_conf.
330 */
331
332login_cap_t *
333login_getuserclass(const struct passwd *pwd)
334{
335    return login_getclassbyname(LOGIN_MECLASS, pwd);
336}
337
338
339
340/*
341 * login_getcapstr()
342 * Given a login_cap entry, and a capability name, return the
343 * value defined for that capability, a defualt if not found, or
344 * an error string on error.
345 */
346
347const char *
348login_getcapstr(login_cap_t *lc, const char *cap, const char *def, const char *error)
349{
350    char    *res;
351    int	    ret;
352
353    if (lc == NULL || cap == NULL || lc->lc_cap == NULL || *cap == '\0')
354	return def;
355
356    if ((ret = cgetstr(lc->lc_cap, cap, &res)) == -1)
357	return def;
358    return (ret >= 0) ? res : error;
359}
360
361
362/*
363 * login_getcaplist()
364 * Given a login_cap entry, and a capability name, return the
365 * value defined for that capability split into an array of
366 * strings.
367 */
368
369const char **
370login_getcaplist(login_cap_t *lc, const char *cap, const char *chars)
371{
372    const char *lstring;
373
374    if (chars == NULL)
375	chars = ", \t";
376    if ((lstring = login_getcapstr(lc, cap, NULL, NULL)) != NULL)
377	return arrayize(lstring, chars, NULL);
378    return NULL;
379}
380
381
382/*
383 * login_getpath()
384 * From the login_cap_t <lc>, get the capability <cap> which is
385 * formatted as either a space or comma delimited list of paths
386 * and append them all into a string and separate by semicolons.
387 * If there is an error of any kind, return <error>.
388 */
389
390const char *
391login_getpath(login_cap_t *lc, const char *cap, const char *error)
392{
393    const char *str;
394    char *ptr;
395    int count;
396
397    str = login_getcapstr(lc, cap, NULL, NULL);
398    if (str == NULL)
399	return error;
400    ptr = __DECONST(char *, str); /* XXXX Yes, very dodgy */
401    while (*ptr) {
402	count = strcspn(ptr, ", \t");
403	ptr += count;
404	if (*ptr)
405	    *ptr++ = ':';
406    }
407    return str;
408}
409
410
411static int
412isinfinite(const char *s)
413{
414    static const char *infs[] = {
415	"infinity",
416	"inf",
417	"unlimited",
418	"unlimit",
419	"-1",
420	NULL
421    };
422    const char **i = &infs[0];
423
424    while (*i != NULL) {
425	if (strcasecmp(s, *i) == 0)
426	    return 1;
427	++i;
428    }
429    return 0;
430}
431
432
433static u_quad_t
434rmultiply(u_quad_t n1, u_quad_t n2)
435{
436    u_quad_t	m, r;
437    int		b1, b2;
438
439    static int bpw = 0;
440
441    /* Handle simple cases */
442    if (n1 == 0 || n2 == 0)
443	return 0;
444    if (n1 == 1)
445	return n2;
446    if (n2 == 1)
447	return n1;
448
449    /*
450     * sizeof() returns number of bytes needed for storage.
451     * This may be different from the actual number of useful bits.
452     */
453    if (!bpw) {
454	bpw = sizeof(u_quad_t) * 8;
455	while (((u_quad_t)1 << (bpw-1)) == 0)
456	    --bpw;
457    }
458
459    /*
460     * First check the magnitude of each number. If the sum of the
461     * magnatude is way to high, reject the number. (If this test
462     * is not done then the first multiply below may overflow.)
463     */
464    for (b1 = bpw; (((u_quad_t)1 << (b1-1)) & n1) == 0; --b1)
465	;
466    for (b2 = bpw; (((u_quad_t)1 << (b2-1)) & n2) == 0; --b2)
467	;
468    if (b1 + b2 - 2 > bpw) {
469	errno = ERANGE;
470	return (UQUAD_MAX);
471    }
472
473    /*
474     * Decompose the multiplication to be:
475     * h1 = n1 & ~1
476     * h2 = n2 & ~1
477     * l1 = n1 & 1
478     * l2 = n2 & 1
479     * (h1 + l1) * (h2 + l2)
480     * (h1 * h2) + (h1 * l2) + (l1 * h2) + (l1 * l2)
481     *
482     * Since h1 && h2 do not have the low bit set, we can then say:
483     *
484     * (h1>>1 * h2>>1 * 4) + ...
485     *
486     * So if (h1>>1 * h2>>1) > (1<<(bpw - 2)) then the result will
487     * overflow.
488     *
489     * Finally, if MAX - ((h1 * l2) + (l1 * h2) + (l1 * l2)) < (h1*h2)
490     * then adding in residual amout will cause an overflow.
491     */
492
493    m = (n1 >> 1) * (n2 >> 1);
494    if (m >= ((u_quad_t)1 << (bpw-2))) {
495	errno = ERANGE;
496	return (UQUAD_MAX);
497    }
498    m *= 4;
499
500    r = (n1 & n2 & 1)
501	+ (n2 & 1) * (n1 & ~(u_quad_t)1)
502	+ (n1 & 1) * (n2 & ~(u_quad_t)1);
503
504    if ((u_quad_t)(m + r) < m) {
505	errno = ERANGE;
506	return (UQUAD_MAX);
507    }
508    m += r;
509
510    return (m);
511}
512
513
514/*
515 * login_getcaptime()
516 * From the login_cap_t <lc>, get the capability <cap>, which is
517 * formatted as a time (e.g., "<cap>=10h3m2s").  If <cap> is not
518 * present in <lc>, return <def>; if there is an error of some kind,
519 * return <error>.
520 */
521
522rlim_t
523login_getcaptime(login_cap_t *lc, const char *cap, rlim_t def, rlim_t error)
524{
525    char    *res, *ep, *oval;
526    int	    r;
527    rlim_t  tot;
528
529    errno = 0;
530    if (lc == NULL || lc->lc_cap == NULL)
531	return def;
532
533    /*
534     * Look for <cap> in lc_cap.
535     * If it's not there (-1), return <def>.
536     * If there's an error, return <error>.
537     */
538
539    if ((r = cgetstr(lc->lc_cap, cap, &res)) == -1)
540	return def;
541    else if (r < 0) {
542	errno = ERANGE;
543	return error;
544    }
545
546    /* "inf" and "infinity" are special cases */
547    if (isinfinite(res))
548	return RLIM_INFINITY;
549
550    /*
551     * Now go through the string, turning something like 1h2m3s into
552     * an integral value.  Whee.
553     */
554
555    errno = 0;
556    tot = 0;
557    oval = res;
558    while (*res) {
559	rlim_t tim = strtoq(res, &ep, 0);
560	rlim_t mult = 1;
561
562	if (ep == NULL || ep == res || errno != 0) {
563	invalid:
564	    syslog(LOG_WARNING, "login_getcaptime: class '%s' bad value %s=%s",
565		   lc->lc_class, cap, oval);
566	    errno = ERANGE;
567	    return error;
568	}
569	/* Look for suffixes */
570	switch (*ep++) {
571	case 0:
572	    ep--;
573	    break;	/* end of string */
574	case 's': case 'S':	/* seconds */
575	    break;
576	case 'm': case 'M':	/* minutes */
577	    mult = 60;
578	    break;
579	case 'h': case 'H':	/* hours */
580	    mult = 60L * 60L;
581	    break;
582	case 'd': case 'D':	/* days */
583	    mult = 60L * 60L * 24L;
584	    break;
585	case 'w': case 'W':	/* weeks */
586	    mult = 60L * 60L * 24L * 7L;
587	    break;
588	case 'y': case 'Y':	/* 365-day years */
589	    mult = 60L * 60L * 24L * 365L;
590	    break;
591	default:
592	    goto invalid;
593	}
594	res = ep;
595	tot += rmultiply(tim, mult);
596	if (errno)
597	    goto invalid;
598    }
599
600    return tot;
601}
602
603
604/*
605 * login_getcapnum()
606 * From the login_cap_t <lc>, extract the numerical value <cap>.
607 * If it is not present, return <def> for a default, and return
608 * <error> if there is an error.
609 * Like login_getcaptime(), only it only converts to a number, not
610 * to a time; "infinity" and "inf" are 'special.'
611 */
612
613rlim_t
614login_getcapnum(login_cap_t *lc, const char *cap, rlim_t def, rlim_t error)
615{
616    char    *ep, *res;
617    int	    r;
618    rlim_t  val;
619
620    if (lc == NULL || lc->lc_cap == NULL)
621	return def;
622
623    /*
624     * For BSDI compatibility, try for the tag=<val> first
625     */
626    if ((r = cgetstr(lc->lc_cap, cap, &res)) == -1) {
627	long	lval;
628	/* string capability not present, so try for tag#<val> as numeric */
629	if ((r = cgetnum(lc->lc_cap, cap, &lval)) == -1)
630	    return def; /* Not there, so return default */
631	else if (r >= 0)
632	    return (rlim_t)lval;
633    }
634
635    if (r < 0) {
636	errno = ERANGE;
637	return error;
638    }
639
640    if (isinfinite(res))
641	return RLIM_INFINITY;
642
643    errno = 0;
644    val = strtoq(res, &ep, 0);
645    if (ep == NULL || ep == res || errno != 0) {
646	syslog(LOG_WARNING, "login_getcapnum: class '%s' bad value %s=%s",
647	       lc->lc_class, cap, res);
648	errno = ERANGE;
649	return error;
650    }
651
652    return val;
653}
654
655
656
657/*
658 * login_getcapsize()
659 * From the login_cap_t <lc>, extract the capability <cap>, which is
660 * formatted as a size (e.g., "<cap>=10M"); it can also be "infinity".
661 * If not present, return <def>, or <error> if there is an error of
662 * some sort.
663 */
664
665rlim_t
666login_getcapsize(login_cap_t *lc, const char *cap, rlim_t def, rlim_t error)
667{
668    char    *ep, *res, *oval;
669    int	    r;
670    rlim_t  tot;
671
672    if (lc == NULL || lc->lc_cap == NULL)
673	return def;
674
675    if ((r = cgetstr(lc->lc_cap, cap, &res)) == -1)
676	return def;
677    else if (r < 0) {
678	errno = ERANGE;
679	return error;
680    }
681
682    if (isinfinite(res))
683	return RLIM_INFINITY;
684
685    errno = 0;
686    tot = 0;
687    oval = res;
688    while (*res) {
689	rlim_t siz = strtoq(res, &ep, 0);
690	rlim_t mult = 1;
691
692	if (ep == NULL || ep == res || errno != 0) {
693	invalid:
694	    syslog(LOG_WARNING, "login_getcapsize: class '%s' bad value %s=%s",
695		   lc->lc_class, cap, oval);
696	    errno = ERANGE;
697	    return error;
698	}
699	switch (*ep++) {
700	case 0:	/* end of string */
701	    ep--;
702	    break;
703	case 'b': case 'B':	/* 512-byte blocks */
704	    mult = 512;
705	    break;
706	case 'k': case 'K':	/* 1024-byte Kilobytes */
707	    mult = 1024;
708	    break;
709	case 'm': case 'M':	/* 1024-k kbytes */
710	    mult = 1024 * 1024;
711	    break;
712	case 'g': case 'G':	/* 1Gbyte */
713	    mult = 1024 * 1024 * 1024;
714	    break;
715	case 't': case 'T':	/* 1TBte */
716	    mult = 1024LL * 1024LL * 1024LL * 1024LL;
717	    break;
718	default:
719	    goto invalid;
720	}
721	res = ep;
722	tot += rmultiply(siz, mult);
723	if (errno)
724	    goto invalid;
725    }
726
727    return tot;
728}
729
730
731/*
732 * login_getcapbool()
733 * From the login_cap_t <lc>, check for the existance of the capability
734 * of <cap>.  Return <def> if <lc>->lc_cap is NULL, otherwise return
735 * the whether or not <cap> exists there.
736 */
737
738int
739login_getcapbool(login_cap_t *lc, const char *cap, int def)
740{
741    if (lc == NULL || lc->lc_cap == NULL)
742	return def;
743    return (cgetcap(lc->lc_cap, cap, ':') != NULL);
744}
745
746
747/*
748 * login_getstyle()
749 * Given a login_cap entry <lc>, and optionally a type of auth <auth>,
750 * and optionally a style <style>, find the style that best suits these
751 * rules:
752 *	1.  If <auth> is non-null, look for an "auth-<auth>=" string
753 *	in the capability; if not present, default to "auth=".
754 *	2.  If there is no auth list found from (1), default to
755 *	"passwd" as an authorization list.
756 *	3.  If <style> is non-null, look for <style> in the list of
757 *	authorization methods found from (2); if <style> is NULL, default
758 *	to LOGIN_DEFSTYLE ("passwd").
759 *	4.  If the chosen style is found in the chosen list of authorization
760 *	methods, return that; otherwise, return NULL.
761 * E.g.:
762 *     login_getstyle(lc, NULL, "ftp");
763 *     login_getstyle(lc, "login", NULL);
764 *     login_getstyle(lc, "skey", "network");
765 */
766
767const char *
768login_getstyle(login_cap_t *lc, const char *style, const char *auth)
769{
770    int	    i;
771    const char **authtypes = NULL;
772    char    *auths= NULL;
773    char    realauth[64];
774
775    static const char *defauthtypes[] = { LOGIN_DEFSTYLE, NULL };
776
777    if (auth != NULL && *auth != '\0') {
778	if (snprintf(realauth, sizeof realauth, "auth-%s", auth) < (int)sizeof(realauth))
779	    authtypes = login_getcaplist(lc, realauth, NULL);
780    }
781
782    if (authtypes == NULL)
783	authtypes = login_getcaplist(lc, "auth", NULL);
784
785    if (authtypes == NULL)
786	authtypes = defauthtypes;
787
788    /*
789     * We have at least one authtype now; auths is a comma-separated
790     * (or space-separated) list of authentication types.  We have to
791     * convert from this to an array of char*'s; authtypes then gets this.
792     */
793    i = 0;
794    if (style != NULL && *style != '\0') {
795	while (authtypes[i] != NULL && strcmp(style, authtypes[i]) != 0)
796	    i++;
797    }
798
799    lc->lc_style = NULL;
800    if (authtypes[i] != NULL && (auths = strdup(authtypes[i])) != NULL)
801	lc->lc_style = auths;
802
803    if (lc->lc_style != NULL)
804	lc->lc_style = strdup(lc->lc_style);
805
806    return lc->lc_style;
807}
808