lib/libutil/login_class.c

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