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/9/lib/libutil/login_class.c 273931 2014-11-01 13:45:01Z dim $");
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 { NULL, 0, 0 }
70 };
71
72
73 void
setclassresources(login_cap_t * lc)74 setclassresources(login_cap_t *lc)
75 {
76 struct login_res *lr;
77
78 if (lc == NULL)
79 return;
80
81 for (lr = resources; lr->what != NULL; ++lr) {
82 struct rlimit rlim;
83
84 /*
85 * The login.conf file can have <limit>, <limit>-max, and
86 * <limit>-cur entries.
87 * What we do is get the current current- and maximum- limits.
88 * Then, we try to get an entry for <limit> from the capability,
89 * using the current and max limits we just got as the
90 * default/error values.
91 * *Then*, we try looking for <limit>-cur and <limit>-max,
92 * again using the appropriate values as the default/error
93 * conditions.
94 */
95
96 if (getrlimit(lr->why, &rlim) != 0)
97 syslog(LOG_ERR, "getting %s resource limit: %m", lr->what);
98 else {
99 char name_cur[40];
100 char name_max[40];
101 rlim_t rcur = rlim.rlim_cur;
102 rlim_t rmax = rlim.rlim_max;
103
104 sprintf(name_cur, "%s-cur", lr->what);
105 sprintf(name_max, "%s-max", lr->what);
106
107 rcur = (*lr->who)(lc, lr->what, rcur, rcur);
108 rmax = (*lr->who)(lc, lr->what, rmax, rmax);
109 rlim.rlim_cur = (*lr->who)(lc, name_cur, rcur, rcur);
110 rlim.rlim_max = (*lr->who)(lc, name_max, rmax, rmax);
111
112 if (setrlimit(lr->why, &rlim) == -1)
113 syslog(LOG_WARNING, "set class '%s' resource limit %s: %m", lc->lc_class, lr->what);
114 }
115 }
116 }
117
118
119
120 static struct login_vars {
121 const char *tag;
122 const char *var;
123 const char *def;
124 int overwrite;
125 } pathvars[] = {
126 { "path", "PATH", NULL, 1},
127 { "cdpath", "CDPATH", NULL, 1},
128 { "manpath", "MANPATH", NULL, 1},
129 { NULL, NULL, NULL, 0}
130 }, envars[] = {
131 { "lang", "LANG", NULL, 1},
132 { "charset", "MM_CHARSET", NULL, 1},
133 { "timezone", "TZ", NULL, 1},
134 { "term", "TERM", NULL, 0},
135 { NULL, NULL, NULL, 0}
136 };
137
138 static char *
substvar(const char * var,const struct passwd * pwd,int hlen,int pch,int nlen)139 substvar(const char * var, const struct passwd * pwd, int hlen, int pch, int nlen)
140 {
141 char *np = NULL;
142
143 if (var != NULL) {
144 int tildes = 0;
145 int dollas = 0;
146 char *p;
147 const char *q;
148
149 if (pwd != NULL) {
150 for (q = var; *q != '\0'; ++q) {
151 tildes += (*q == '~');
152 dollas += (*q == '$');
153 }
154 }
155
156 np = malloc(strlen(var) + (dollas * nlen)
157 - dollas + (tildes * (pch+hlen))
158 - tildes + 1);
159
160 if (np != NULL) {
161 p = strcpy(np, var);
162
163 if (pwd != NULL) {
164 /*
165 * This loop does user username and homedir substitutions
166 * for unescaped $ (username) and ~ (homedir)
167 */
168 while (*(p += strcspn(p, "~$")) != '\0') {
169 int l = strlen(p);
170
171 if (p > np && *(p-1) == '\\') /* Escaped: */
172 memmove(p - 1, p, l + 1); /* Slide-out the backslash */
173 else if (*p == '~') {
174 int v = pch && *(p+1) != '/'; /* Avoid double // */
175 memmove(p + hlen + v, p + 1, l); /* Subst homedir */
176 memmove(p, pwd->pw_dir, hlen);
177 if (v)
178 p[hlen] = '/';
179 p += hlen + v;
180 }
181 else /* if (*p == '$') */ {
182 memmove(p + nlen, p + 1, l); /* Subst username */
183 memmove(p, pwd->pw_name, nlen);
184 p += nlen;
185 }
186 }
187 }
188 }
189 }
190
191 return (np);
192 }
193
194
195 void
setclassenvironment(login_cap_t * lc,const struct passwd * pwd,int paths)196 setclassenvironment(login_cap_t *lc, const struct passwd * pwd, int paths)
197 {
198 struct login_vars *vars = paths ? pathvars : envars;
199 int hlen = pwd ? strlen(pwd->pw_dir) : 0;
200 int nlen = pwd ? strlen(pwd->pw_name) : 0;
201 char pch = 0;
202
203 if (hlen && pwd->pw_dir[hlen-1] != '/')
204 ++pch;
205
206 while (vars->tag != NULL) {
207 const char * var = paths ? login_getpath(lc, vars->tag, NULL)
208 : login_getcapstr(lc, vars->tag, NULL, NULL);
209
210 char * np = substvar(var, pwd, hlen, pch, nlen);
211
212 if (np != NULL) {
213 setenv(vars->var, np, vars->overwrite);
214 free(np);
215 } else if (vars->def != NULL) {
216 setenv(vars->var, vars->def, 0);
217 }
218 ++vars;
219 }
220
221 /*
222 * If we're not processing paths, then see if there is a setenv list by
223 * which the admin and/or user may set an arbitrary set of env vars.
224 */
225 if (!paths) {
226 const char **set_env = login_getcaplist(lc, "setenv", ",");
227
228 if (set_env != NULL) {
229 while (*set_env != NULL) {
230 char *p = strchr(*set_env, '=');
231
232 if (p != NULL) { /* Discard invalid entries */
233 char *np;
234
235 *p++ = '\0';
236 if ((np = substvar(p, pwd, hlen, pch, nlen)) != NULL) {
237 setenv(*set_env, np, 1);
238 free(np);
239 }
240 }
241 ++set_env;
242 }
243 }
244 }
245 }
246
247
248 static int
list2cpuset(const char * list,cpuset_t * mask)249 list2cpuset(const char *list, cpuset_t *mask)
250 {
251 enum { NONE, NUM, DASH } state;
252 int lastnum;
253 int curnum;
254 const char *l;
255
256 state = NONE;
257 curnum = lastnum = 0;
258 for (l = list; *l != '\0';) {
259 if (isdigit(*l)) {
260 curnum = atoi(l);
261 if (curnum > CPU_SETSIZE)
262 errx(EXIT_FAILURE,
263 "Only %d cpus supported", CPU_SETSIZE);
264 while (isdigit(*l))
265 l++;
266 switch (state) {
267 case NONE:
268 lastnum = curnum;
269 state = NUM;
270 break;
271 case DASH:
272 for (; lastnum <= curnum; lastnum++)
273 CPU_SET(lastnum, mask);
274 state = NONE;
275 break;
276 case NUM:
277 default:
278 return (0);
279 }
280 continue;
281 }
282 switch (*l) {
283 case ',':
284 switch (state) {
285 case NONE:
286 break;
287 case NUM:
288 CPU_SET(curnum, mask);
289 state = NONE;
290 break;
291 case DASH:
292 return (0);
293 break;
294 }
295 break;
296 case '-':
297 if (state != NUM)
298 return (0);
299 state = DASH;
300 break;
301 default:
302 return (0);
303 }
304 l++;
305 }
306 switch (state) {
307 case NONE:
308 break;
309 case NUM:
310 CPU_SET(curnum, mask);
311 break;
312 case DASH:
313 return (0);
314 }
315 return (1);
316 }
317
318
319 void
setclasscpumask(login_cap_t * lc)320 setclasscpumask(login_cap_t *lc)
321 {
322 const char *maskstr;
323 cpuset_t maskset;
324 cpusetid_t setid;
325
326 maskstr = login_getcapstr(lc, "cpumask", NULL, NULL);
327 CPU_ZERO(&maskset);
328 if (maskstr == NULL)
329 return;
330 if (strcasecmp("default", maskstr) == 0)
331 return;
332 if (!list2cpuset(maskstr, &maskset)) {
333 syslog(LOG_WARNING,
334 "list2cpuset(%s) invalid mask specification", maskstr);
335 return;
336 }
337
338 if (cpuset(&setid) != 0) {
339 syslog(LOG_ERR, "cpuset(): %s", strerror(errno));
340 return;
341 }
342
343 if (cpuset_setaffinity(CPU_LEVEL_CPUSET, CPU_WHICH_PID, -1,
344 sizeof(maskset), &maskset) != 0)
345 syslog(LOG_ERR, "cpuset_setaffinity(%s): %s", maskstr,
346 strerror(errno));
347 }
348
349
350 /*
351 * setclasscontext()
352 *
353 * For the login class <class>, set various class context values
354 * (limits, mainly) to the values for that class. Which values are
355 * set are controlled by <flags> -- see <login_class.h> for the
356 * possible values.
357 *
358 * setclasscontext() can only set resources, priority, and umask.
359 */
360
361 int
setclasscontext(const char * classname,unsigned int flags)362 setclasscontext(const char *classname, unsigned int flags)
363 {
364 int rc;
365 login_cap_t *lc;
366
367 lc = login_getclassbyname(classname, NULL);
368
369 flags &= LOGIN_SETRESOURCES | LOGIN_SETPRIORITY |
370 LOGIN_SETUMASK | LOGIN_SETPATH;
371
372 rc = lc ? setusercontext(lc, NULL, 0, flags) : -1;
373 login_close(lc);
374 return (rc);
375 }
376
377
378
379 /*
380 * Private function which takes care of processing
381 */
382
383 static mode_t
setlogincontext(login_cap_t * lc,const struct passwd * pwd,mode_t mymask,unsigned long flags)384 setlogincontext(login_cap_t *lc, const struct passwd *pwd,
385 mode_t mymask, unsigned long flags)
386 {
387 if (lc) {
388 /* Set resources */
389 if (flags & LOGIN_SETRESOURCES)
390 setclassresources(lc);
391 /* See if there's a umask override */
392 if (flags & LOGIN_SETUMASK)
393 mymask = (mode_t)login_getcapnum(lc, "umask", mymask, mymask);
394 /* Set paths */
395 if (flags & LOGIN_SETPATH)
396 setclassenvironment(lc, pwd, 1);
397 /* Set environment */
398 if (flags & LOGIN_SETENV)
399 setclassenvironment(lc, pwd, 0);
400 /* Set cpu affinity */
401 if (flags & LOGIN_SETCPUMASK)
402 setclasscpumask(lc);
403 }
404 return (mymask);
405 }
406
407
408
409 /*
410 * setusercontext()
411 *
412 * Given a login class <lc> and a user in <pwd>, with a uid <uid>,
413 * set the context as in setclasscontext(). <flags> controls which
414 * values are set.
415 *
416 * The difference between setclasscontext() and setusercontext() is
417 * that the former sets things up for an already-existing process,
418 * while the latter sets things up from a root context. Such as might
419 * be called from login(1).
420 *
421 */
422
423 int
setusercontext(login_cap_t * lc,const struct passwd * pwd,uid_t uid,unsigned int flags)424 setusercontext(login_cap_t *lc, const struct passwd *pwd, uid_t uid, unsigned int flags)
425 {
426 rlim_t p;
427 mode_t mymask;
428 login_cap_t *llc = NULL;
429 struct sigaction sa, prevsa;
430 struct rtprio rtp;
431 int error;
432
433 if (lc == NULL) {
434 if (pwd != NULL && (lc = login_getpwclass(pwd)) != NULL)
435 llc = lc; /* free this when we're done */
436 }
437
438 if (flags & LOGIN_SETPATH)
439 pathvars[0].def = uid ? _PATH_DEFPATH : _PATH_STDPATH;
440
441 /* we need a passwd entry to set these */
442 if (pwd == NULL)
443 flags &= ~(LOGIN_SETGROUP | LOGIN_SETLOGIN | LOGIN_SETMAC);
444
445 /* Set the process priority */
446 if (flags & LOGIN_SETPRIORITY) {
447 p = login_getcapnum(lc, "priority", LOGIN_DEFPRI, LOGIN_DEFPRI);
448
449 if (p > PRIO_MAX) {
450 rtp.type = RTP_PRIO_IDLE;
451 p -= PRIO_MAX + 1;
452 rtp.prio = p > RTP_PRIO_MAX ? RTP_PRIO_MAX : p;
453 if (rtprio(RTP_SET, 0, &rtp))
454 syslog(LOG_WARNING, "rtprio '%s' (%s): %m",
455 pwd ? pwd->pw_name : "-",
456 lc ? lc->lc_class : LOGIN_DEFCLASS);
457 } else if (p < PRIO_MIN) {
458 rtp.type = RTP_PRIO_REALTIME;
459 p -= PRIO_MIN - RTP_PRIO_MAX;
460 rtp.prio = p < RTP_PRIO_MIN ? RTP_PRIO_MIN : 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 {
466 if (setpriority(PRIO_PROCESS, 0, (int)p) != 0)
467 syslog(LOG_WARNING, "setpriority '%s' (%s): %m",
468 pwd ? pwd->pw_name : "-",
469 lc ? lc->lc_class : LOGIN_DEFCLASS);
470 }
471 }
472
473 /* Setup the user's group permissions */
474 if (flags & LOGIN_SETGROUP) {
475 if (setgid(pwd->pw_gid) != 0) {
476 syslog(LOG_ERR, "setgid(%lu): %m", (u_long)pwd->pw_gid);
477 login_close(llc);
478 return (-1);
479 }
480 if (initgroups(pwd->pw_name, pwd->pw_gid) == -1) {
481 syslog(LOG_ERR, "initgroups(%s,%lu): %m", pwd->pw_name,
482 (u_long)pwd->pw_gid);
483 login_close(llc);
484 return (-1);
485 }
486 }
487
488 /* Set up the user's MAC label. */
489 if ((flags & LOGIN_SETMAC) && mac_is_present(NULL) == 1) {
490 const char *label_string;
491 mac_t label;
492
493 label_string = login_getcapstr(lc, "label", NULL, NULL);
494 if (label_string != NULL) {
495 if (mac_from_text(&label, label_string) == -1) {
496 syslog(LOG_ERR, "mac_from_text('%s') for %s: %m",
497 pwd->pw_name, label_string);
498 return (-1);
499 }
500 if (mac_set_proc(label) == -1)
501 error = errno;
502 else
503 error = 0;
504 mac_free(label);
505 if (error != 0) {
506 syslog(LOG_ERR, "mac_set_proc('%s') for %s: %s",
507 label_string, pwd->pw_name, strerror(error));
508 return (-1);
509 }
510 }
511 }
512
513 /* Set the sessions login */
514 if ((flags & LOGIN_SETLOGIN) && setlogin(pwd->pw_name) != 0) {
515 syslog(LOG_ERR, "setlogin(%s): %m", pwd->pw_name);
516 login_close(llc);
517 return (-1);
518 }
519
520 /* Inform the kernel about current login class */
521 if (lc != NULL && lc->lc_class != NULL && (flags & LOGIN_SETLOGINCLASS)) {
522 /*
523 * XXX: This is a workaround to fail gracefully in case the kernel
524 * does not support setloginclass(2).
525 */
526 bzero(&sa, sizeof(sa));
527 sa.sa_handler = SIG_IGN;
528 sigfillset(&sa.sa_mask);
529 sigaction(SIGSYS, &sa, &prevsa);
530 error = setloginclass(lc->lc_class);
531 sigaction(SIGSYS, &prevsa, NULL);
532 if (error != 0) {
533 syslog(LOG_ERR, "setloginclass(%s): %m", lc->lc_class);
534 #ifdef notyet
535 login_close(llc);
536 return (-1);
537 #endif
538 }
539 }
540
541 mymask = (flags & LOGIN_SETUMASK) ? umask(LOGIN_DEFUMASK) : 0;
542 mymask = setlogincontext(lc, pwd, mymask, flags);
543 login_close(llc);
544
545 /* This needs to be done after anything that needs root privs */
546 if ((flags & LOGIN_SETUSER) && setuid(uid) != 0) {
547 syslog(LOG_ERR, "setuid(%lu): %m", (u_long)uid);
548 return (-1); /* Paranoia again */
549 }
550
551 /*
552 * Now, we repeat some of the above for the user's private entries
553 */
554 if (getuid() == uid && (lc = login_getuserclass(pwd)) != NULL) {
555 mymask = setlogincontext(lc, pwd, mymask, flags);
556 login_close(lc);
557 }
558
559 /* Finally, set any umask we've found */
560 if (flags & LOGIN_SETUMASK)
561 umask(mymask);
562
563 return (0);
564 }
565