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  * $FreeBSD: src/lib/libutil/login_class.c,v 1.14.2.3 2002/08/06 07:07:52 ache Exp $
  25  * $DragonFly: src/lib/libutil/login_class.c,v 1.5 2006/01/12 14:43:10 corecode Exp $
  26  */
  27
  28 #include <sys/types.h>
  29 #include <sys/stat.h>
  30 #include <sys/time.h>
  31 #include <sys/resource.h>
  32 #include <sys/rtprio.h>
  33
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <paths.h>
  37 #include <pwd.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include <syslog.h>
  42 #include <unistd.h>
  43
  44 #include "login_cap.h"
  45
  46
  47 static struct login_res {
  48     const char *what;
  49     rlim_t (*who)(login_cap_t *, const char *, rlim_t, rlim_t);
  50     int why;
  51 } resources[] = {
  52     { "cputime",        login_getcaptime,       RLIMIT_CPU      },
  53     { "filesize",       login_getcapsize,       RLIMIT_FSIZE    },
  54     { "datasize",       login_getcapsize,       RLIMIT_DATA     },
  55     { "stacksize",      login_getcapsize,       RLIMIT_STACK    },
  56     { "memoryuse",      login_getcapsize,       RLIMIT_RSS      },
  57     { "memorylocked",   login_getcapsize,       RLIMIT_MEMLOCK  },
  58     { "maxproc",        login_getcapnum,        RLIMIT_NPROC    },
  59     { "openfiles",      login_getcapnum,        RLIMIT_NOFILE   },
  60     { "coredumpsize",   login_getcapsize,       RLIMIT_CORE     },
  61     { "sbsize",         login_getcapsize,       RLIMIT_SBSIZE   },
  62     { "vmemoryuse",     login_getcapsize,       RLIMIT_VMEM     },
  63 #ifdef RLIMIT_POSIXLOCKS
  64     { "posixlocks",     login_getcapnum,        RLIMIT_POSIXLOCKS },
  65 #endif
  66     { NULL,             0,                      0               }
  67 };
  68
  69
  70 void
  71 setclassresources(login_cap_t *lc)
  72 {
  73     struct login_res *lr;
  74
  75     if (lc == NULL)
  76         return;
  77
  78     for (lr = resources; lr->what != NULL; ++lr) {
  79         struct rlimit   rlim;
  80
  81         /*
  82          * The login.conf file can have <limit>, <limit>-max, and
  83          * <limit>-cur entries.
  84          * What we do is get the current current- and maximum- limits.
  85          * Then, we try to get an entry for <limit> from the capability,
  86          * using the current and max limits we just got as the
  87          * default/error values.
  88          * *Then*, we try looking for <limit>-cur and <limit>-max,
  89          * again using the appropriate values as the default/error
  90          * conditions.
  91          */
  92
  93         if (getrlimit(lr->why, &rlim) != 0)
  94             syslog(LOG_ERR, "getting %s resource limit: %m", lr->what);
  95         else {
  96             char        name_cur[40];
  97             char        name_max[40];
  98             rlim_t      rcur = rlim.rlim_cur;
  99             rlim_t      rmax = rlim.rlim_max;
 100
 101             sprintf(name_cur, "%s-cur", lr->what);
 102             sprintf(name_max, "%s-max", lr->what);
 103
 104             rcur = (*lr->who)(lc, lr->what, rcur, rcur);
 105             rmax = (*lr->who)(lc, lr->what, rmax, rmax);
 106             rlim.rlim_cur = (*lr->who)(lc, name_cur, rcur, rcur);
 107             rlim.rlim_max = (*lr->who)(lc, name_max, rmax, rmax);
 108
 109             if (setrlimit(lr->why, &rlim) == -1)
 110                 syslog(LOG_WARNING, "set class '%s' resource limit %s: %m", lc->lc_class, lr->what);
 111         }
 112     }
 113 }
 114
 115
 116
 117 static struct login_vars {
 118     const char *tag;
 119     const char *var;
 120     const char *def;
 121     int overwrite;
 122 } pathvars[] = {
 123     { "path",           "PATH",       NULL, 1},
 124     { "cdpath",         "CDPATH",     NULL, 1},
 125     { "manpath",        "MANPATH",    NULL, 1},
 126     { NULL,             NULL,         NULL, 0}
 127 }, envars[] = {
 128     { "lang",           "LANG",       NULL, 1},
 129     { "charset",        "MM_CHARSET", NULL, 1},
 130     { "timezone",       "TZ",         NULL, 1},
 131     { "term",           "TERM",       NULL, 0},
 132     { NULL,             NULL,         NULL, 0}
 133 };
 134
 135 static char *
 136 substvar(char * var, const struct passwd * pwd, int hlen, int pch, int nlen)
 137 {
 138     char    *np = NULL;
 139
 140     if (var != NULL) {
 141         int     tildes = 0;
 142         int     dollas = 0;
 143         char    *p;
 144
 145         if (pwd != NULL) {
 146             /* Count the number of ~'s in var to substitute */
 147             p = var;
 148             for (p = var; (p = strchr(p, '~')) != NULL; p++)
 149                 ++tildes;
 150             /* Count the number of $'s in var to substitute */
 151             p = var;
 152             for (p = var; (p = strchr(p, '$')) != NULL; p++)
 153                 ++dollas;
 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 int
 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         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             if (setenv(vars->var, np, vars->overwrite) == -1) {
 214                 syslog(LOG_ERR, "setclassenvironment: %m");
 215                 free(np);
 216                 return -1;
 217             }
 218             free(np);
 219         } else if (vars->def != NULL) {
 220             if (setenv(vars->var, vars->def, 0) == -1) {
 221                 syslog(LOG_ERR, "setclassenvironment: %m");
 222                 return -1;
 223             }
 224         }
 225         ++vars;
 226     }
 227
 228     /*
 229      * If we're not processing paths, then see if there is a setenv list by
 230      * which the admin and/or user may set an arbitrary set of env vars.
 231      */
 232     if (!paths) {
 233         char    **set_env = login_getcaplist(lc, "setenv", ",");
 234
 235         if (set_env != NULL) {
 236             while (*set_env != NULL) {
 237                 char    *p = strchr(*set_env, '=');
 238
 239                 if (p != NULL) {  /* Discard invalid entries */
 240                     char        *np;
 241
 242                     *p++ = '\0';
 243                     if ((np = substvar(p, pwd, hlen, pch, nlen)) != NULL) {
 244                         if (setenv(*set_env, np, 1) == -1) {
 245                             free(np);
 246                             return -1;
 247                         }
 248                         free(np);
 249                     }
 250                 }
 251                 ++set_env;
 252             }
 253         }
 254     }
 255     return 0;
 256 }
 257
 258
 259 /*
 260  * setclasscontext()
 261  *
 262  * For the login class <class>, set various class context values
 263  * (limits, mainly) to the values for that class.  Which values are
 264  * set are controlled by <flags> -- see <login_class.h> for the
 265  * possible values.
 266  *
 267  * setclasscontext() can only set resources, priority, and umask.
 268  */
 269
 270 int
 271 setclasscontext(const char *classname, unsigned int flags)
 272 {
 273     int         rc;
 274     login_cap_t *lc;
 275
 276     lc = login_getclassbyname(classname, NULL);
 277
 278     flags &= LOGIN_SETRESOURCES | LOGIN_SETPRIORITY |
 279             LOGIN_SETUMASK | LOGIN_SETPATH;
 280
 281     rc = lc ? setusercontext(lc, NULL, 0, flags) : -1;
 282     login_close(lc);
 283     return rc;
 284 }
 285
 286
 287
 288 /*
 289  * Private functionw which takes care of processing
 290  */
 291
 292 static mode_t
 293 setlogincontext(login_cap_t *lc, const struct passwd *pwd,
 294                 mode_t mymask, unsigned long flags, int *errcode)
 295 {
 296     *errcode = 0;
 297     if (lc) {
 298         /* Set resources */
 299         if (flags & LOGIN_SETRESOURCES)
 300             setclassresources(lc);
 301         /* See if there's a umask override */
 302         if (flags & LOGIN_SETUMASK)
 303             mymask = (mode_t)login_getcapnum(lc, "umask", mymask, mymask);
 304         /* Set paths */
 305         if (flags & LOGIN_SETPATH) {
 306             if (setclassenvironment(lc, pwd, 1) == -1)
 307                 *errcode = -1;
 308         }
 309         /* Set environment */
 310         if (flags & LOGIN_SETENV) {
 311             if (setclassenvironment(lc, pwd, 0) == -1)
 312                 *errcode = -1;
 313         }
 314     }
 315     return mymask;
 316 }
 317
 318
 319
 320 /*
 321  * setusercontext()
 322  *
 323  * Given a login class <lc> and a user in <pwd>, with a uid <uid>,
 324  * set the context as in setclasscontext().  <flags> controls which
 325  * values are set.
 326  *
 327  * The difference between setclasscontext() and setusercontext() is
 328  * that the former sets things up for an already-existing process,
 329  * while the latter sets things up from a root context.  Such as might
 330  * be called from login(1).
 331  *
 332  */
 333
 334 int
 335 setusercontext(login_cap_t *lc, const struct passwd *pwd, uid_t uid, unsigned int flags)
 336 {
 337     quad_t      p;
 338     mode_t      mymask;
 339     login_cap_t *llc = NULL;
 340 #ifndef __NETBSD_SYSCALLS
 341     struct rtprio rtp;
 342 #endif
 343     int         errcode;
 344
 345     if (lc == NULL) {
 346         if (pwd != NULL && (lc = login_getpwclass(pwd)) != NULL)
 347             llc = lc; /* free this when we're done */
 348     }
 349
 350     if (flags & LOGIN_SETPATH)
 351         pathvars[0].def = uid ? _PATH_DEFPATH : _PATH_STDPATH;
 352
 353     /* we need a passwd entry to set these */
 354     if (pwd == NULL)
 355         flags &= ~(LOGIN_SETGROUP | LOGIN_SETLOGIN);
 356
 357     /* Set the process priority */
 358     if (flags & LOGIN_SETPRIORITY) {
 359         p = login_getcapnum(lc, "priority", LOGIN_DEFPRI, LOGIN_DEFPRI);
 360
 361         if(p > PRIO_MAX) {
 362 #ifndef __NETBSD_SYSCALLS
 363             rtp.type = RTP_PRIO_IDLE;
 364             rtp.prio = p - PRIO_MAX - 1;
 365             p = (rtp.prio > RTP_PRIO_MAX) ? 31 : p;
 366             if(rtprio(RTP_SET, 0, &rtp))
 367                 syslog(LOG_WARNING, "rtprio '%s' (%s): %m",
 368                     pwd->pw_name, lc ? lc->lc_class : LOGIN_DEFCLASS);
 369 #endif
 370         } else if(p < PRIO_MIN) {
 371 #ifndef __NETBSD_SYSCALLS
 372             rtp.type = RTP_PRIO_REALTIME;
 373             rtp.prio = abs(p - PRIO_MIN + RTP_PRIO_MAX);
 374             p = (rtp.prio > RTP_PRIO_MAX) ? 1 : p;
 375             if(rtprio(RTP_SET, 0, &rtp))
 376                 syslog(LOG_WARNING, "rtprio '%s' (%s): %m",
 377                     pwd->pw_name, lc ? lc->lc_class : LOGIN_DEFCLASS);
 378 #endif
 379         } else {
 380             if (setpriority(PRIO_PROCESS, 0, (int)p) != 0)
 381                 syslog(LOG_WARNING, "setpriority '%s' (%s): %m",
 382                     pwd->pw_name, lc ? lc->lc_class : LOGIN_DEFCLASS);
 383         }
 384     }
 385
 386     /* Setup the user's group permissions */
 387     if (flags & LOGIN_SETGROUP) {
 388         if (setgid(pwd->pw_gid) != 0) {
 389             syslog(LOG_ERR, "setgid(%lu): %m", (u_long)pwd->pw_gid);
 390             login_close(llc);
 391             return -1;
 392         }
 393         if (initgroups(pwd->pw_name, pwd->pw_gid) == -1) {
 394             syslog(LOG_ERR, "initgroups(%s,%lu): %m", pwd->pw_name,
 395                    (u_long)pwd->pw_gid);
 396             login_close(llc);
 397             return -1;
 398         }
 399     }
 400
 401     /* Set the sessions login */
 402     if ((flags & LOGIN_SETLOGIN) && setlogin(pwd->pw_name) != 0) {
 403         syslog(LOG_ERR, "setlogin(%s): %m", pwd->pw_name);
 404         login_close(llc);
 405         return -1;
 406     }
 407
 408     mymask = (flags & LOGIN_SETUMASK) ? umask(LOGIN_DEFUMASK) : 0;
 409     mymask = setlogincontext(lc, pwd, mymask, flags, &errcode);
 410     if (errcode == -1) {
 411         login_close(llc);
 412         return -1;
 413     }
 414     login_close(llc);
 415
 416     /* This needs to be done after anything that needs root privs */
 417     if ((flags & LOGIN_SETUSER) && setuid(uid) != 0) {
 418         syslog(LOG_ERR, "setuid(%lu): %m", (u_long)uid);
 419         return -1;      /* Paranoia again */
 420     }
 421
 422     /*
 423      * Now, we repeat some of the above for the user's private entries
 424      */
 425     if ((lc = login_getuserclass(pwd)) != NULL) {
 426         mymask = setlogincontext(lc, pwd, mymask, flags, &errcode);
 427         if (errcode == -1) {
 428             login_close(lc);
 429             return -1;
 430         }
 431         login_close(lc);
 432     }
 433
 434     /* Finally, set any umask we've found */
 435     if (flags & LOGIN_SETUMASK)
 436         umask(mymask);
 437
 438     return 0;
 439 }
 440