56c0434453
o Incorporated BSDI code and enhancements, better logging for error checking (which has been shown to be a problem, and is therefore justified, imho); also some minor things we were missing, including better quad_t math, which checks for under/overflows. o setusercontext() now allows user resource limit overrides, but does this AFTER dropping root privs, to restrict the user to droping hard limits and set soft limits within the kernel's allowed user limits. o umask() only set once, and only if requested. o add _secure_path(), and use in login.conf to guard against symlinks etc. and non-root owned or non-user owned files being used. Derived from BSDI contributed code. o revamped authentication code to BSDI's latest api, which includes deleting authenticate() and adding auth_check() and a few other functions. This is still marked as depecated in BSDI, but is included for completeness. No other source in the tree uses this anyway, so it is now bracketed with #ifdef LOGIN_CAP_AUTH which is by default not defined. Only auth_checknologin() and auth_cat() are actually used in module login_auth.c. o AUTH_NONE definition removed (collided with other includes in the tree). [bde] o BSDI's login_getclass() now accepts a char *classname parameter rather than struct passwd *pwd. We now do likewise, but added login_getpwclass() for (sort of) backwards compatiblity, namely because we handle root as a special case for the default class. This will require quite a few changes elsewhere in the source tree. o We no longer pretend to support rlim_t as a long type. o Revised code formatting to be more bsd-ish style.
388 lines
10 KiB
C
388 lines
10 KiB
C
/*-
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* Copyright (c) 1996 by
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* Sean Eric Fagan <sef@kithrup.com>
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* David Nugent <davidn@blaze.net.au>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, is permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice immediately at the beginning of the file, without modification,
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* this list of conditions, and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. This work was done expressly for inclusion into FreeBSD. Other use
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* is permitted provided this notation is included.
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* 4. Absolutely no warranty of function or purpose is made by the authors.
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* 5. Modifications may be freely made to this file providing the above
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* conditions are met.
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*
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* High-level routines relating to use of the user capabilities database
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*
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* $Id: login_class.c,v 1.5 1997/02/22 15:08:22 peter Exp $
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <sys/resource.h>
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#include <fcntl.h>
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#include <pwd.h>
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#include <syslog.h>
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#include <login_cap.h>
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#include <paths.h>
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#undef UNKNOWN
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#define UNKNOWN "su"
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static struct login_res {
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const char *what;
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rlim_t (*who)(login_cap_t *, const char *, rlim_t, rlim_t);
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int why;
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} resources[] = {
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{ "cputime", login_getcaptime, RLIMIT_CPU },
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{ "filesize", login_getcapsize, RLIMIT_FSIZE },
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{ "datasize", login_getcapsize, RLIMIT_DATA },
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{ "stacksize", login_getcapsize, RLIMIT_STACK },
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{ "memoryuse", login_getcapsize, RLIMIT_RSS },
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{ "memorylocked", login_getcapsize, RLIMIT_MEMLOCK },
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{ "maxproc", login_getcapnum, RLIMIT_NPROC },
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{ "openfiles", login_getcapnum, RLIMIT_NOFILE },
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{ "coredumpsize", login_getcapsize, RLIMIT_CORE },
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{ NULL, 0, 0 }
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};
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void
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setclassresources(login_cap_t *lc)
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{
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struct login_res *lr;
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if (lc == NULL)
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return;
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for (lr = resources; lr->what != NULL; ++lr) {
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struct rlimit rlim;
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/*
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* The login.conf file can have <limit>, <limit>-max, and
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* <limit>-cur entries.
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* What we do is get the current current- and maximum- limits.
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* Then, we try to get an entry for <limit> from the capability,
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* using the current and max limits we just got as the
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* default/error values.
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* *Then*, we try looking for <limit>-cur and <limit>-max,
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* again using the appropriate values as the default/error
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* conditions.
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*/
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if (getrlimit(lr->why, &rlim) != 0)
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syslog(LOG_ERR, "getting %s resource limit: %m", lr->what);
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else {
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char name_cur[40];
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char name_max[40];
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rlim_t rcur = rlim.rlim_cur;
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rlim_t rmax = rlim.rlim_max;
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sprintf(name_cur, "%s-cur", lr->what);
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sprintf(name_max, "%s-max", lr->what);
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rcur = (*lr->who)(lc, lr->what, rcur, rcur);
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rmax = (*lr->who)(lc, lr->what, rmax, rmax);
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rlim.rlim_cur = (*lr->who)(lc, name_cur, rcur, rcur);
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rlim.rlim_max = (*lr->who)(lc, name_max, rmax, rmax);
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if (setrlimit(lr->why, &rlim) == -1)
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syslog(LOG_WARNING, "set class '%s' resource limit %s: %m", lc->lc_class, lr->what);
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}
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}
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}
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static struct login_vars {
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const char *tag;
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const char *var;
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const char *def;
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} pathvars[] = {
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{ "path", "PATH", NULL },
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{ "cdpath", "CDPATH", NULL },
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{ "manpath", "MANPATH", NULL },
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{ NULL, NULL, NULL }
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}, envars[] = {
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{ "lang", "LANG", NULL },
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{ "charset", "MM_CHARSET", NULL },
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{ "timezone", "TZ", NULL },
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{ "term", "TERM", UNKNOWN },
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{ NULL, NULL, NULL }
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};
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static char *
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substvar(char * var, const struct passwd * pwd, int hlen, int pch, int nlen)
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{
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char *np = NULL;
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if (var != NULL) {
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int tildes = 0;
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int dollas = 0;
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char *p;
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if (pwd != NULL) {
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/* Count the number of ~'s in var to substitute */
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p = var;
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for (p = var; (p = strchr(p, '~')) != NULL; p++)
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++tildes;
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/* Count the number of $'s in var to substitute */
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p = var;
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for (p = var; (p = strchr(p, '$')) != NULL; p++)
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++dollas;
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}
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np = malloc(strlen(var) + (dollas * nlen)
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- dollas + (tildes * (pch+hlen))
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- tildes + 1);
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if (np != NULL) {
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p = strcpy(np, var);
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if (pwd != NULL) {
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/*
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* This loop does user username and homedir substitutions
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* for unescaped $ (username) and ~ (homedir)
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*/
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while (*(p += strcspn(p, "~$")) != '\0') {
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int l = strlen(p);
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if (p > var && *(p-1) == '\\') /* Escaped: */
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memmove(p - 1, p, l + 1); /* Slide-out the backslash */
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else if (*p == '~') {
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int v = pch && *(p+1) != '/'; /* Avoid double // */
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memmove(p + hlen + v, p + 1, l); /* Subst homedir */
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memmove(p, pwd->pw_dir, hlen);
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if (v)
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p[hlen] = '/';
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p += hlen + v;
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}
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else /* if (*p == '$') */ {
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memmove(p + nlen, p + 1, l); /* Subst username */
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memmove(p, pwd->pw_name, nlen);
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p += nlen;
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}
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}
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}
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}
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}
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return np;
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}
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void
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setclassenvironment(login_cap_t *lc, const struct passwd * pwd, int paths)
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{
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struct login_vars *vars = paths ? pathvars : envars;
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int hlen = pwd ? strlen(pwd->pw_dir) : 0;
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int nlen = pwd ? strlen(pwd->pw_name) : 0;
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char pch = 0;
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if (hlen && pwd->pw_dir[hlen-1] != '/')
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++pch;
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while (vars->tag != NULL) {
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char * var = paths ? login_getpath(lc, vars->tag, NULL)
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: login_getcapstr(lc, vars->tag, NULL, NULL);
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char * np = substvar(var, pwd, hlen, pch, nlen);
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if (np != NULL) {
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setenv(vars->var, np, 1);
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free(np);
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} else if (vars->def != NULL) {
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setenv(vars->var, vars->def, 0);
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}
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++vars;
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}
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/*
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* If we're not processing paths, then see if there is a setenv list by
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* which the admin and/or user may set an arbitrary set of env vars.
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*/
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if (!paths) {
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char **set_env = login_getcaplist(lc, "setenv", ",");
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if (set_env != NULL) {
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while (*set_env != NULL) {
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char *p = strchr(*set_env, '=');
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if (p != NULL) { /* Discard invalid entries */
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char *np;
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*p++ = '\0';
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if ((np = substvar(p, pwd, hlen, pch, nlen)) != NULL) {
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setenv(*set_env, np, 1);
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free(np);
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}
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}
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++set_env;
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}
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}
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}
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}
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/*
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* setclasscontext()
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*
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* For the login class <class>, set various class context values
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* (limits, mainly) to the values for that class. Which values are
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* set are controlled by <flags> -- see <login_class.h> for the
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* possible values.
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*
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* setclasscontext() can only set resources, priority, and umask.
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*/
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int
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setclasscontext(const char *classname, unsigned int flags)
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{
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int rc;
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login_cap_t *lc;
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lc = login_getclassbyname(classname, NULL);
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flags &= LOGIN_SETRESOURCES | LOGIN_SETPRIORITY |
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LOGIN_SETUMASK | LOGIN_SETPATH;
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rc = lc ? setusercontext(lc, NULL, 0, flags) : -1;
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login_close(lc);
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return rc;
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}
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/*
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* Private functionw which takes care of processing
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*/
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static mode_t
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setlogincontext(login_cap_t *lc, const struct passwd *pwd,
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mode_t mymask, unsigned long flags)
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{
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if (lc) {
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/* Set resources */
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if (flags & LOGIN_SETRESOURCES)
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setclassresources(lc);
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/* See if there's a umask override */
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if (flags & LOGIN_SETUMASK)
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mymask = (mode_t)login_getcapnum(lc, "umask", mymask, mymask);
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/* Set paths */
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if (flags & LOGIN_SETPATH)
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setclassenvironment(lc, pwd, 1);
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/* Set environment */
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if (flags & LOGIN_SETENV)
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setclassenvironment(lc, pwd, 0);
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}
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return mymask;
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}
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/*
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* setusercontext()
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*
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* Given a login class <lc> and a user in <pwd>, with a uid <uid>,
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* set the context as in setclasscontext(). <flags> controls which
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* values are set.
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*
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* The difference between setclasscontext() and setusercontext() is
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* that the former sets things up for an already-existing process,
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* while the latter sets things up from a root context. Such as might
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* be called from login(1).
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*
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*/
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int
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setusercontext(login_cap_t *lc, const struct passwd *pwd, uid_t uid, unsigned int flags)
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{
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quad_t p;
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mode_t mymask;
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login_cap_t *llc = NULL;
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if (lc == NULL) {
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if (pwd != NULL && (lc = login_getpwclass(pwd)) != NULL)
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llc = lc; /* free this when we're done */
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}
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if (flags & LOGIN_SETPATH)
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pathvars[0].def = uid ? _PATH_DEFPATH : _PATH_STDPATH;
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/* we need a passwd entry to set these */
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if (pwd == NULL)
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flags &= ~(LOGIN_SETGROUP | LOGIN_SETLOGIN);
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/* Set the process priority */
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if (flags & LOGIN_SETPRIORITY) {
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p = login_getcapnum(lc, "priority", LOGIN_DEFPRI, LOGIN_DEFPRI);
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p = (p < PRIO_MIN || p > PRIO_MAX) ? LOGIN_DEFPRI : p;
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if (setpriority(PRIO_PROCESS, 0, (int)p) != 0)
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syslog(LOG_WARNING, "setpriority '%s' (%s): %m",
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pwd->pw_name, lc ? lc->lc_class : LOGIN_DEFCLASS);
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}
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/* Setup the user's group permissions */
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if (flags & LOGIN_SETGROUP) {
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if (setgid(pwd->pw_gid) != 0) {
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syslog(LOG_ERR, "setgid(%ld): %m", (long)pwd->pw_gid);
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login_close(llc);
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return -1;
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}
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if (initgroups(pwd->pw_name, pwd->pw_gid) == -1) {
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syslog(LOG_ERR, "initgroups(%s,%ld): %m", pwd->pw_name,
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pwd->pw_gid);
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login_close(llc);
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return -1;
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}
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}
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/* Set the sessions login */
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if ((flags & LOGIN_SETLOGIN) && setlogin(pwd->pw_name) != 0) {
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syslog(LOG_ERR, "setlogin(%s): %m", pwd->pw_name);
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login_close(llc);
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return -1;
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}
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mymask = (flags & LOGIN_SETUMASK) ? umask(LOGIN_DEFUMASK) : 0;
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mymask = setlogincontext(lc, pwd, mymask, flags);
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login_close(llc);
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/* This needs to be done after anything that needs root privs */
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if ((flags & LOGIN_SETUSER) && setuid(uid) != 0) {
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syslog(LOG_ERR, "setuid(%ld): %m", uid);
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return -1; /* Paranoia again */
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}
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/*
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* Now, we repeat some of the above for the user's private entries
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*/
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if ((lc = login_getuserclass(pwd)) != NULL) {
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mymask = setlogincontext(lc, pwd, mymask, flags);
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login_close(lc);
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}
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/* Finally, set any umask we've found */
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if (flags & LOGIN_SETUMASK)
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umask(mymask);
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return 0;
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}
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