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 * Redistribution and use in source and binary forms, with or without
8 * modification, is permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice immediately at the beginning of the file, without modification,
12 * this list of conditions, and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. This work was done expressly for inclusion into FreeBSD. Other use
17 * is permitted provided this notation is included.
18 * 4. Absolutely no warranty of function or purpose is made by the authors.
19 * 5. Modifications may be freely made to this file providing the above
20 * conditions are met.
21 *
22 * High-level routines relating to use of the user capabilities database
23 */
24
25 #include <sys/cdefs.h>
26 __FBSDID("$FreeBSD: stable/12/lib/libutil/login_class.c 369610 2021-04-15 19:23:32Z git2svn $");
27
28 #include <sys/param.h>
29 #include <sys/cpuset.h>
30 #include <sys/mac.h>
31 #include <sys/resource.h>
32 #include <sys/rtprio.h>
33 #include <sys/stat.h>
34 #include <sys/time.h>
35
36 #include <ctype.h>
37 #include <err.h>
38 #include <errno.h>
39 #include <fcntl.h>
40 #include <login_cap.h>
41 #include <paths.h>
42 #include <pwd.h>
43 #include <signal.h>
44 #include <stdio.h>
45 #include <stdlib.h>
46 #include <string.h>
47 #include <syslog.h>
48 #include <unistd.h>
49
50
51 static struct login_res {
52 const char *what;
53 rlim_t (*who)(login_cap_t *, const char *, rlim_t, rlim_t);
54 int why;
55 } resources[] = {
56 { "cputime", login_getcaptime, RLIMIT_CPU },
57 { "filesize", login_getcapsize, RLIMIT_FSIZE },
58 { "datasize", login_getcapsize, RLIMIT_DATA },
59 { "stacksize", login_getcapsize, RLIMIT_STACK },
60 { "memoryuse", login_getcapsize, RLIMIT_RSS },
61 { "memorylocked", login_getcapsize, RLIMIT_MEMLOCK },
62 { "maxproc", login_getcapnum, RLIMIT_NPROC },
63 { "openfiles", login_getcapnum, RLIMIT_NOFILE },
64 { "coredumpsize", login_getcapsize, RLIMIT_CORE },
65 { "sbsize", login_getcapsize, RLIMIT_SBSIZE },
66 { "vmemoryuse", login_getcapsize, RLIMIT_VMEM },
67 { "pseudoterminals", login_getcapnum, RLIMIT_NPTS },
68 { "swapuse", login_getcapsize, RLIMIT_SWAP },
69 { "kqueues", login_getcapsize, RLIMIT_KQUEUES },
70 { "umtxp", login_getcapnum, RLIMIT_UMTXP },
71 { NULL, 0, 0 }
72 };
73
74
75 void
setclassresources(login_cap_t * lc)76 setclassresources(login_cap_t *lc)
77 {
78 struct login_res *lr;
79
80 if (lc == NULL)
81 return;
82
83 for (lr = resources; lr->what != NULL; ++lr) {
84 struct rlimit rlim;
85
86 /*
87 * The login.conf file can have <limit>, <limit>-max, and
88 * <limit>-cur entries.
89 * What we do is get the current current- and maximum- limits.
90 * Then, we try to get an entry for <limit> from the capability,
91 * using the current and max limits we just got as the
92 * default/error values.
93 * *Then*, we try looking for <limit>-cur and <limit>-max,
94 * again using the appropriate values as the default/error
95 * conditions.
96 */
97
98 if (getrlimit(lr->why, &rlim) != 0)
99 syslog(LOG_ERR, "getting %s resource limit: %m", lr->what);
100 else {
101 char name_cur[40];
102 char name_max[40];
103 rlim_t rcur = rlim.rlim_cur;
104 rlim_t rmax = rlim.rlim_max;
105
106 sprintf(name_cur, "%s-cur", lr->what);
107 sprintf(name_max, "%s-max", lr->what);
108
109 rcur = (*lr->who)(lc, lr->what, rcur, rcur);
110 rmax = (*lr->who)(lc, lr->what, rmax, rmax);
111 rlim.rlim_cur = (*lr->who)(lc, name_cur, rcur, rcur);
112 rlim.rlim_max = (*lr->who)(lc, name_max, rmax, rmax);
113
114 if (setrlimit(lr->why, &rlim) == -1)
115 syslog(LOG_WARNING, "set class '%s' resource limit %s: %m", lc->lc_class, lr->what);
116 }
117 }
118 }
119
120
121
122 static struct login_vars {
123 const char *tag;
124 const char *var;
125 const char *def;
126 int overwrite;
127 } pathvars[] = {
128 { "path", "PATH", NULL, 1},
129 { "cdpath", "CDPATH", NULL, 1},
130 { "manpath", "MANPATH", NULL, 1},
131 { NULL, NULL, NULL, 0}
132 }, envars[] = {
133 { "lang", "LANG", NULL, 1},
134 { "charset", "MM_CHARSET", NULL, 1},
135 { "mail", "MAIL", NULL, 1},
136 { "timezone", "TZ", NULL, 1},
137 { "term", "TERM", NULL, 0},
138 { NULL, NULL, NULL, 0}
139 };
140
141 static char *
substvar(const char * var,const struct passwd * pwd,int hlen,int pch,int nlen)142 substvar(const char * var, const struct passwd * pwd, int hlen, int pch, int nlen)
143 {
144 char *np = NULL;
145
146 if (var != NULL) {
147 int tildes = 0;
148 int dollas = 0;
149 char *p;
150 const char *q;
151
152 if (pwd != NULL) {
153 for (q = var; *q != '\0'; ++q) {
154 tildes += (*q == '~');
155 dollas += (*q == '$');
156 }
157 }
158
159 np = malloc(strlen(var) + (dollas * nlen)
160 - dollas + (tildes * (pch+hlen))
161 - tildes + 1);
162
163 if (np != NULL) {
164 p = strcpy(np, var);
165
166 if (pwd != NULL) {
167 /*
168 * This loop does user username and homedir substitutions
169 * for unescaped $ (username) and ~ (homedir)
170 */
171 while (*(p += strcspn(p, "~$")) != '\0') {
172 int l = strlen(p);
173
174 if (p > np && *(p-1) == '\\') /* Escaped: */
175 memmove(p - 1, p, l + 1); /* Slide-out the backslash */
176 else if (*p == '~') {
177 int v = pch && *(p+1) != '/'; /* Avoid double // */
178 memmove(p + hlen + v, p + 1, l); /* Subst homedir */
179 memmove(p, pwd->pw_dir, hlen);
180 if (v)
181 p[hlen] = '/';
182 p += hlen + v;
183 }
184 else /* if (*p == '$') */ {
185 memmove(p + nlen, p + 1, l); /* Subst username */
186 memmove(p, pwd->pw_name, nlen);
187 p += nlen;
188 }
189 }
190 }
191 }
192 }
193
194 return (np);
195 }
196
197
198 void
setclassenvironment(login_cap_t * lc,const struct passwd * pwd,int paths)199 setclassenvironment(login_cap_t *lc, const struct passwd * pwd, int paths)
200 {
201 struct login_vars *vars = paths ? pathvars : envars;
202 int hlen = pwd ? strlen(pwd->pw_dir) : 0;
203 int nlen = pwd ? strlen(pwd->pw_name) : 0;
204 char pch = 0;
205
206 if (hlen && pwd->pw_dir[hlen-1] != '/')
207 ++pch;
208
209 while (vars->tag != NULL) {
210 const char * var = paths ? login_getpath(lc, vars->tag, NULL)
211 : login_getcapstr(lc, vars->tag, NULL, NULL);
212
213 char * np = substvar(var, pwd, hlen, pch, nlen);
214
215 if (np != NULL) {
216 setenv(vars->var, np, vars->overwrite);
217 free(np);
218 } else if (vars->def != NULL) {
219 setenv(vars->var, vars->def, 0);
220 }
221 ++vars;
222 }
223
224 /*
225 * If we're not processing paths, then see if there is a setenv list by
226 * which the admin and/or user may set an arbitrary set of env vars.
227 */
228 if (!paths) {
229 const char **set_env = login_getcaplist(lc, "setenv", ",");
230
231 if (set_env != NULL) {
232 while (*set_env != NULL) {
233 char *p = strchr(*set_env, '=');
234
235 if (p != NULL && p != *set_env) { /* Discard invalid entries */
236 const char *ep;
237 char *np;
238
239 *p++ = '\0';
240 /* Strip leading spaces from variable name */
241 ep = *set_env;
242 while (*ep == ' ' || *ep == '\t')
243 ep++;
244 if ((np = substvar(p, pwd, hlen, pch, nlen)) != NULL) {
245 setenv(ep, np, 1);
246 free(np);
247 }
248 }
249 ++set_env;
250 }
251 }
252 }
253 }
254
255
256 static int
list2cpuset(const char * list,cpuset_t * mask)257 list2cpuset(const char *list, cpuset_t *mask)
258 {
259 enum { NONE, NUM, DASH } state;
260 int lastnum;
261 int curnum;
262 const char *l;
263
264 state = NONE;
265 curnum = lastnum = 0;
266 for (l = list; *l != '\0';) {
267 if (isdigit(*l)) {
268 curnum = atoi(l);
269 if (curnum > CPU_SETSIZE)
270 errx(EXIT_FAILURE,
271 "Only %d cpus supported", CPU_SETSIZE);
272 while (isdigit(*l))
273 l++;
274 switch (state) {
275 case NONE:
276 lastnum = curnum;
277 state = NUM;
278 break;
279 case DASH:
280 for (; lastnum <= curnum; lastnum++)
281 CPU_SET(lastnum, mask);
282 state = NONE;
283 break;
284 case NUM:
285 default:
286 return (0);
287 }
288 continue;
289 }
290 switch (*l) {
291 case ',':
292 switch (state) {
293 case NONE:
294 break;
295 case NUM:
296 CPU_SET(curnum, mask);
297 state = NONE;
298 break;
299 case DASH:
300 return (0);
301 break;
302 }
303 break;
304 case '-':
305 if (state != NUM)
306 return (0);
307 state = DASH;
308 break;
309 default:
310 return (0);
311 }
312 l++;
313 }
314 switch (state) {
315 case NONE:
316 break;
317 case NUM:
318 CPU_SET(curnum, mask);
319 break;
320 case DASH:
321 return (0);
322 }
323 return (1);
324 }
325
326
327 void
setclasscpumask(login_cap_t * lc)328 setclasscpumask(login_cap_t *lc)
329 {
330 const char *maskstr;
331 cpuset_t maskset;
332 cpusetid_t setid;
333
334 maskstr = login_getcapstr(lc, "cpumask", NULL, NULL);
335 CPU_ZERO(&maskset);
336 if (maskstr == NULL)
337 return;
338 if (strcasecmp("default", maskstr) == 0)
339 return;
340 if (!list2cpuset(maskstr, &maskset)) {
341 syslog(LOG_WARNING,
342 "list2cpuset(%s) invalid mask specification", maskstr);
343 return;
344 }
345
346 if (cpuset(&setid) != 0) {
347 syslog(LOG_ERR, "cpuset(): %s", strerror(errno));
348 return;
349 }
350
351 if (cpuset_setaffinity(CPU_LEVEL_CPUSET, CPU_WHICH_PID, -1,
352 sizeof(maskset), &maskset) != 0)
353 syslog(LOG_ERR, "cpuset_setaffinity(%s): %s", maskstr,
354 strerror(errno));
355 }
356
357
358 /*
359 * setclasscontext()
360 *
361 * For the login class <class>, set various class context values
362 * (limits, mainly) to the values for that class. Which values are
363 * set are controlled by <flags> -- see <login_class.h> for the
364 * possible values.
365 *
366 * setclasscontext() can only set resources, priority, and umask.
367 */
368
369 int
setclasscontext(const char * classname,unsigned int flags)370 setclasscontext(const char *classname, unsigned int flags)
371 {
372 int rc;
373 login_cap_t *lc;
374
375 lc = login_getclassbyname(classname, NULL);
376
377 flags &= LOGIN_SETRESOURCES | LOGIN_SETPRIORITY |
378 LOGIN_SETUMASK | LOGIN_SETPATH;
379
380 rc = lc ? setusercontext(lc, NULL, 0, flags) : -1;
381 login_close(lc);
382 return (rc);
383 }
384
385
386
387 /*
388 * Private function which takes care of processing
389 */
390
391 static mode_t
setlogincontext(login_cap_t * lc,const struct passwd * pwd,mode_t mymask,unsigned long flags)392 setlogincontext(login_cap_t *lc, const struct passwd *pwd,
393 mode_t mymask, unsigned long flags)
394 {
395 if (lc) {
396 /* Set resources */
397 if (flags & LOGIN_SETRESOURCES)
398 setclassresources(lc);
399 /* See if there's a umask override */
400 if (flags & LOGIN_SETUMASK)
401 mymask = (mode_t)login_getcapnum(lc, "umask", mymask, mymask);
402 /* Set paths */
403 if (flags & LOGIN_SETPATH)
404 setclassenvironment(lc, pwd, 1);
405 /* Set environment */
406 if (flags & LOGIN_SETENV)
407 setclassenvironment(lc, pwd, 0);
408 /* Set cpu affinity */
409 if (flags & LOGIN_SETCPUMASK)
410 setclasscpumask(lc);
411 }
412 return (mymask);
413 }
414
415
416
417 /*
418 * setusercontext()
419 *
420 * Given a login class <lc> and a user in <pwd>, with a uid <uid>,
421 * set the context as in setclasscontext(). <flags> controls which
422 * values are set.
423 *
424 * The difference between setclasscontext() and setusercontext() is
425 * that the former sets things up for an already-existing process,
426 * while the latter sets things up from a root context. Such as might
427 * be called from login(1).
428 *
429 */
430
431 int
setusercontext(login_cap_t * lc,const struct passwd * pwd,uid_t uid,unsigned int flags)432 setusercontext(login_cap_t *lc, const struct passwd *pwd, uid_t uid, unsigned int flags)
433 {
434 rlim_t p;
435 mode_t mymask;
436 login_cap_t *llc = NULL;
437 struct sigaction sa, prevsa;
438 struct rtprio rtp;
439 int error;
440
441 if (lc == NULL) {
442 if (pwd != NULL && (lc = login_getpwclass(pwd)) != NULL)
443 llc = lc; /* free this when we're done */
444 }
445
446 if (flags & LOGIN_SETPATH)
447 pathvars[0].def = uid ? _PATH_DEFPATH : _PATH_STDPATH;
448
449 /* we need a passwd entry to set these */
450 if (pwd == NULL)
451 flags &= ~(LOGIN_SETGROUP | LOGIN_SETLOGIN | LOGIN_SETMAC);
452
453 /* Set the process priority */
454 if (flags & LOGIN_SETPRIORITY) {
455 p = login_getcapnum(lc, "priority", LOGIN_DEFPRI, LOGIN_DEFPRI);
456
457 if (p > PRIO_MAX) {
458 rtp.type = RTP_PRIO_IDLE;
459 p -= PRIO_MAX + 1;
460 rtp.prio = p > RTP_PRIO_MAX ? RTP_PRIO_MAX : p;
461 if (rtprio(RTP_SET, 0, &rtp))
462 syslog(LOG_WARNING, "rtprio '%s' (%s): %m",
463 pwd ? pwd->pw_name : "-",
464 lc ? lc->lc_class : LOGIN_DEFCLASS);
465 } else if (p < PRIO_MIN) {
466 rtp.type = RTP_PRIO_REALTIME;
467 p -= PRIO_MIN - RTP_PRIO_MAX;
468 rtp.prio = p < RTP_PRIO_MIN ? RTP_PRIO_MIN : p;
469 if (rtprio(RTP_SET, 0, &rtp))
470 syslog(LOG_WARNING, "rtprio '%s' (%s): %m",
471 pwd ? pwd->pw_name : "-",
472 lc ? lc->lc_class : LOGIN_DEFCLASS);
473 } else {
474 if (setpriority(PRIO_PROCESS, 0, (int)p) != 0)
475 syslog(LOG_WARNING, "setpriority '%s' (%s): %m",
476 pwd ? pwd->pw_name : "-",
477 lc ? lc->lc_class : LOGIN_DEFCLASS);
478 }
479 }
480
481 /* Setup the user's group permissions */
482 if (flags & LOGIN_SETGROUP) {
483 if (setgid(pwd->pw_gid) != 0) {
484 syslog(LOG_ERR, "setgid(%lu): %m", (u_long)pwd->pw_gid);
485 login_close(llc);
486 return (-1);
487 }
488 if (initgroups(pwd->pw_name, pwd->pw_gid) == -1) {
489 syslog(LOG_ERR, "initgroups(%s,%lu): %m", pwd->pw_name,
490 (u_long)pwd->pw_gid);
491 login_close(llc);
492 return (-1);
493 }
494 }
495
496 /* Set up the user's MAC label. */
497 if ((flags & LOGIN_SETMAC) && mac_is_present(NULL) == 1) {
498 const char *label_string;
499 mac_t label;
500
501 label_string = login_getcapstr(lc, "label", NULL, NULL);
502 if (label_string != NULL) {
503 if (mac_from_text(&label, label_string) == -1) {
504 syslog(LOG_ERR, "mac_from_text('%s') for %s: %m",
505 pwd->pw_name, label_string);
506 return (-1);
507 }
508 if (mac_set_proc(label) == -1)
509 error = errno;
510 else
511 error = 0;
512 mac_free(label);
513 if (error != 0) {
514 syslog(LOG_ERR, "mac_set_proc('%s') for %s: %s",
515 label_string, pwd->pw_name, strerror(error));
516 return (-1);
517 }
518 }
519 }
520
521 /* Set the sessions login */
522 if ((flags & LOGIN_SETLOGIN) && setlogin(pwd->pw_name) != 0) {
523 syslog(LOG_ERR, "setlogin(%s): %m", pwd->pw_name);
524 login_close(llc);
525 return (-1);
526 }
527
528 /* Inform the kernel about current login class */
529 if (lc != NULL && lc->lc_class != NULL && (flags & LOGIN_SETLOGINCLASS)) {
530 /*
531 * XXX: This is a workaround to fail gracefully in case the kernel
532 * does not support setloginclass(2).
533 */
534 bzero(&sa, sizeof(sa));
535 sa.sa_handler = SIG_IGN;
536 sigfillset(&sa.sa_mask);
537 sigaction(SIGSYS, &sa, &prevsa);
538 error = setloginclass(lc->lc_class);
539 sigaction(SIGSYS, &prevsa, NULL);
540 if (error != 0) {
541 syslog(LOG_ERR, "setloginclass(%s): %m", lc->lc_class);
542 #ifdef notyet
543 login_close(llc);
544 return (-1);
545 #endif
546 }
547 }
548
549 mymask = (flags & LOGIN_SETUMASK) ? umask(LOGIN_DEFUMASK) : 0;
550 mymask = setlogincontext(lc, pwd, mymask, flags);
551 login_close(llc);
552
553 /* This needs to be done after anything that needs root privs */
554 if ((flags & LOGIN_SETUSER) && setuid(uid) != 0) {
555 syslog(LOG_ERR, "setuid(%lu): %m", (u_long)uid);
556 return (-1); /* Paranoia again */
557 }
558
559 /*
560 * Now, we repeat some of the above for the user's private entries
561 */
562 if (getuid() == uid && (lc = login_getuserclass(pwd)) != NULL) {
563 mymask = setlogincontext(lc, pwd, mymask, flags);
564 login_close(lc);
565 }
566
567 /* Finally, set any umask we've found */
568 if (flags & LOGIN_SETUMASK)
569 umask(mymask);
570
571 return (0);
572 }
573