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freebsd-dev/lib/libutil/login_class.c
Eitan Adler 0bdc3ecf11 Fix NULL ptr dereference in setusercontext if pwd is null, 
LOGIN_SETPRIORITY is set, and setting the priority (rtprio or
setpriority) fails.

PR:		kern/164238
Submitted by:	Alexander Wittig <alexander@wittig.name>
Reviewed by:	des
Approved by:	cperciva
MFC after:	1 month
2012-02-09 21:06:47 +00:00

565 lines
14 KiB
C
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/*-
* Copyright (c) 1996 by
* Sean Eric Fagan <sef@kithrup.com>
* David Nugent <davidn@blaze.net.au>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, is permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice immediately at the beginning of the file, without modification,
* this list of conditions, and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. This work was done expressly for inclusion into FreeBSD. Other use
* is permitted provided this notation is included.
* 4. Absolutely no warranty of function or purpose is made by the authors.
* 5. Modifications may be freely made to this file providing the above
* conditions are met.
*
* High-level routines relating to use of the user capabilities database
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/cpuset.h>
#include <sys/mac.h>
#include <sys/resource.h>
#include <sys/rtprio.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <login_cap.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
static struct login_res {
const char *what;
rlim_t (*who)(login_cap_t *, const char *, rlim_t, rlim_t);
int why;
} resources[] = {
{ "cputime", login_getcaptime, RLIMIT_CPU },
{ "filesize", login_getcapsize, RLIMIT_FSIZE },
{ "datasize", login_getcapsize, RLIMIT_DATA },
{ "stacksize", login_getcapsize, RLIMIT_STACK },
{ "memoryuse", login_getcapsize, RLIMIT_RSS },
{ "memorylocked", login_getcapsize, RLIMIT_MEMLOCK },
{ "maxproc", login_getcapnum, RLIMIT_NPROC },
{ "openfiles", login_getcapnum, RLIMIT_NOFILE },
{ "coredumpsize", login_getcapsize, RLIMIT_CORE },
{ "sbsize", login_getcapsize, RLIMIT_SBSIZE },
{ "vmemoryuse", login_getcapsize, RLIMIT_VMEM },
{ "pseudoterminals", login_getcapnum, RLIMIT_NPTS },
{ "swapuse", login_getcapsize, RLIMIT_SWAP },
{ NULL, 0, 0 }
};
void
setclassresources(login_cap_t *lc)
{
struct login_res *lr;
if (lc == NULL)
return;
for (lr = resources; lr->what != NULL; ++lr) {
struct rlimit rlim;
/*
* The login.conf file can have <limit>, <limit>-max, and
* <limit>-cur entries.
* What we do is get the current current- and maximum- limits.
* Then, we try to get an entry for <limit> from the capability,
* using the current and max limits we just got as the
* default/error values.
* *Then*, we try looking for <limit>-cur and <limit>-max,
* again using the appropriate values as the default/error
* conditions.
*/
if (getrlimit(lr->why, &rlim) != 0)
syslog(LOG_ERR, "getting %s resource limit: %m", lr->what);
else {
char name_cur[40];
char name_max[40];
rlim_t rcur = rlim.rlim_cur;
rlim_t rmax = rlim.rlim_max;
sprintf(name_cur, "%s-cur", lr->what);
sprintf(name_max, "%s-max", lr->what);
rcur = (*lr->who)(lc, lr->what, rcur, rcur);
rmax = (*lr->who)(lc, lr->what, rmax, rmax);
rlim.rlim_cur = (*lr->who)(lc, name_cur, rcur, rcur);
rlim.rlim_max = (*lr->who)(lc, name_max, rmax, rmax);
if (setrlimit(lr->why, &rlim) == -1)
syslog(LOG_WARNING, "set class '%s' resource limit %s: %m", lc->lc_class, lr->what);
}
}
}
static struct login_vars {
const char *tag;
const char *var;
const char *def;
int overwrite;
} pathvars[] = {
{ "path", "PATH", NULL, 1},
{ "cdpath", "CDPATH", NULL, 1},
{ "manpath", "MANPATH", NULL, 1},
{ NULL, NULL, NULL, 0}
}, envars[] = {
{ "lang", "LANG", NULL, 1},
{ "charset", "MM_CHARSET", NULL, 1},
{ "timezone", "TZ", NULL, 1},
{ "term", "TERM", NULL, 0},
{ NULL, NULL, NULL, 0}
};
static char *
substvar(const char * var, const struct passwd * pwd, int hlen, int pch, int nlen)
{
char *np = NULL;
if (var != NULL) {
int tildes = 0;
int dollas = 0;
char *p;
const char *q;
if (pwd != NULL) {
for (q = var; *q != '\0'; ++q) {
tildes += (*q == '~');
dollas += (*q == '$');
}
}
np = malloc(strlen(var) + (dollas * nlen)
- dollas + (tildes * (pch+hlen))
- tildes + 1);
if (np != NULL) {
p = strcpy(np, var);
if (pwd != NULL) {
/*
* This loop does user username and homedir substitutions
* for unescaped $ (username) and ~ (homedir)
*/
while (*(p += strcspn(p, "~$")) != '\0') {
int l = strlen(p);
if (p > np && *(p-1) == '\\') /* Escaped: */
memmove(p - 1, p, l + 1); /* Slide-out the backslash */
else if (*p == '~') {
int v = pch && *(p+1) != '/'; /* Avoid double // */
memmove(p + hlen + v, p + 1, l); /* Subst homedir */
memmove(p, pwd->pw_dir, hlen);
if (v)
p[hlen] = '/';
p += hlen + v;
}
else /* if (*p == '$') */ {
memmove(p + nlen, p + 1, l); /* Subst username */
memmove(p, pwd->pw_name, nlen);
p += nlen;
}
}
}
}
}
return (np);
}
void
setclassenvironment(login_cap_t *lc, const struct passwd * pwd, int paths)
{
struct login_vars *vars = paths ? pathvars : envars;
int hlen = pwd ? strlen(pwd->pw_dir) : 0;
int nlen = pwd ? strlen(pwd->pw_name) : 0;
char pch = 0;
if (hlen && pwd->pw_dir[hlen-1] != '/')
++pch;
while (vars->tag != NULL) {
const char * var = paths ? login_getpath(lc, vars->tag, NULL)
: login_getcapstr(lc, vars->tag, NULL, NULL);
char * np = substvar(var, pwd, hlen, pch, nlen);
if (np != NULL) {
setenv(vars->var, np, vars->overwrite);
free(np);
} else if (vars->def != NULL) {
setenv(vars->var, vars->def, 0);
}
++vars;
}
/*
* If we're not processing paths, then see if there is a setenv list by
* which the admin and/or user may set an arbitrary set of env vars.
*/
if (!paths) {
const char **set_env = login_getcaplist(lc, "setenv", ",");
if (set_env != NULL) {
while (*set_env != NULL) {
char *p = strchr(*set_env, '=');
if (p != NULL) { /* Discard invalid entries */
char *np;
*p++ = '\0';
if ((np = substvar(p, pwd, hlen, pch, nlen)) != NULL) {
setenv(*set_env, np, 1);
free(np);
}
}
++set_env;
}
}
}
}
static int
list2cpuset(const char *list, cpuset_t *mask)
{
enum { NONE, NUM, DASH } state;
int lastnum;
int curnum;
const char *l;
state = NONE;
curnum = lastnum = 0;
for (l = list; *l != '\0';) {
if (isdigit(*l)) {
curnum = atoi(l);
if (curnum > CPU_SETSIZE)
errx(EXIT_FAILURE,
"Only %d cpus supported", CPU_SETSIZE);
while (isdigit(*l))
l++;
switch (state) {
case NONE:
lastnum = curnum;
state = NUM;
break;
case DASH:
for (; lastnum <= curnum; lastnum++)
CPU_SET(lastnum, mask);
state = NONE;
break;
case NUM:
default:
return (0);
}
continue;
}
switch (*l) {
case ',':
switch (state) {
case NONE:
break;
case NUM:
CPU_SET(curnum, mask);
state = NONE;
break;
case DASH:
return (0);
break;
}
break;
case '-':
if (state != NUM)
return (0);
state = DASH;
break;
default:
return (0);
}
l++;
}
switch (state) {
case NONE:
break;
case NUM:
CPU_SET(curnum, mask);
break;
case DASH:
return (0);
}
return (1);
}
void
setclasscpumask(login_cap_t *lc)
{
const char *maskstr;
cpuset_t maskset;
cpusetid_t setid;
maskstr = login_getcapstr(lc, "cpumask", NULL, NULL);
CPU_ZERO(&maskset);
if (maskstr == NULL)
return;
if (strcasecmp("default", maskstr) == 0)
return;
if (!list2cpuset(maskstr, &maskset)) {
syslog(LOG_WARNING,
"list2cpuset(%s) invalid mask specification", maskstr);
return;
}
if (cpuset(&setid) != 0) {
syslog(LOG_ERR, "cpuset(): %s", strerror(errno));
return;
}
if (cpuset_setaffinity(CPU_LEVEL_CPUSET, CPU_WHICH_PID, -1,
sizeof(maskset), &maskset) != 0)
syslog(LOG_ERR, "cpuset_setaffinity(%s): %s", maskstr,
strerror(errno));
}
/*
* setclasscontext()
*
* For the login class <class>, set various class context values
* (limits, mainly) to the values for that class. Which values are
* set are controlled by <flags> -- see <login_class.h> for the
* possible values.
*
* setclasscontext() can only set resources, priority, and umask.
*/
int
setclasscontext(const char *classname, unsigned int flags)
{
int rc;
login_cap_t *lc;
lc = login_getclassbyname(classname, NULL);
flags &= LOGIN_SETRESOURCES | LOGIN_SETPRIORITY |
LOGIN_SETUMASK | LOGIN_SETPATH;
rc = lc ? setusercontext(lc, NULL, 0, flags) : -1;
login_close(lc);
return (rc);
}
/*
* Private function which takes care of processing
*/
static mode_t
setlogincontext(login_cap_t *lc, const struct passwd *pwd,
mode_t mymask, unsigned long flags)
{
if (lc) {
/* Set resources */
if (flags & LOGIN_SETRESOURCES)
setclassresources(lc);
/* See if there's a umask override */
if (flags & LOGIN_SETUMASK)
mymask = (mode_t)login_getcapnum(lc, "umask", mymask, mymask);
/* Set paths */
if (flags & LOGIN_SETPATH)
setclassenvironment(lc, pwd, 1);
/* Set environment */
if (flags & LOGIN_SETENV)
setclassenvironment(lc, pwd, 0);
/* Set cpu affinity */
if (flags & LOGIN_SETCPUMASK)
setclasscpumask(lc);
}
return (mymask);
}
/*
* setusercontext()
*
* Given a login class <lc> and a user in <pwd>, with a uid <uid>,
* set the context as in setclasscontext(). <flags> controls which
* values are set.
*
* The difference between setclasscontext() and setusercontext() is
* that the former sets things up for an already-existing process,
* while the latter sets things up from a root context. Such as might
* be called from login(1).
*
*/
int
setusercontext(login_cap_t *lc, const struct passwd *pwd, uid_t uid, unsigned int flags)
{
quad_t p;
mode_t mymask;
login_cap_t *llc = NULL;
struct sigaction sa, prevsa;
struct rtprio rtp;
int error;
if (lc == NULL) {
if (pwd != NULL && (lc = login_getpwclass(pwd)) != NULL)
llc = lc; /* free this when we're done */
}
if (flags & LOGIN_SETPATH)
pathvars[0].def = uid ? _PATH_DEFPATH : _PATH_STDPATH;
/* we need a passwd entry to set these */
if (pwd == NULL)
flags &= ~(LOGIN_SETGROUP | LOGIN_SETLOGIN | LOGIN_SETMAC);
/* Set the process priority */
if (flags & LOGIN_SETPRIORITY) {
p = login_getcapnum(lc, "priority", LOGIN_DEFPRI, LOGIN_DEFPRI);
if (p > PRIO_MAX) {
rtp.type = RTP_PRIO_IDLE;
rtp.prio = p - PRIO_MAX - 1;
p = (rtp.prio > RTP_PRIO_MAX) ? 31 : p;
if (rtprio(RTP_SET, 0, &rtp))
syslog(LOG_WARNING, "rtprio '%s' (%s): %m",
pwd ? pwd->pw_name : "-",
lc ? lc->lc_class : LOGIN_DEFCLASS);
} else if (p < PRIO_MIN) {
rtp.type = RTP_PRIO_REALTIME;
rtp.prio = abs(p - PRIO_MIN + RTP_PRIO_MAX);
p = (rtp.prio > RTP_PRIO_MAX) ? 1 : p;
if (rtprio(RTP_SET, 0, &rtp))
syslog(LOG_WARNING, "rtprio '%s' (%s): %m",
pwd ? pwd->pw_name : "-",
lc ? lc->lc_class : LOGIN_DEFCLASS);
} else {
if (setpriority(PRIO_PROCESS, 0, (int)p) != 0)
syslog(LOG_WARNING, "setpriority '%s' (%s): %m",
pwd ? pwd->pw_name : "-",
lc ? lc->lc_class : LOGIN_DEFCLASS);
}
}
/* Setup the user's group permissions */
if (flags & LOGIN_SETGROUP) {
if (setgid(pwd->pw_gid) != 0) {
syslog(LOG_ERR, "setgid(%lu): %m", (u_long)pwd->pw_gid);
login_close(llc);
return (-1);
}
if (initgroups(pwd->pw_name, pwd->pw_gid) == -1) {
syslog(LOG_ERR, "initgroups(%s,%lu): %m", pwd->pw_name,
(u_long)pwd->pw_gid);
login_close(llc);
return (-1);
}
}
/* Set up the user's MAC label. */
if ((flags & LOGIN_SETMAC) && mac_is_present(NULL) == 1) {
const char *label_string;
mac_t label;
label_string = login_getcapstr(lc, "label", NULL, NULL);
if (label_string != NULL) {
if (mac_from_text(&label, label_string) == -1) {
syslog(LOG_ERR, "mac_from_text('%s') for %s: %m",
pwd->pw_name, label_string);
return (-1);
}
if (mac_set_proc(label) == -1)
error = errno;
else
error = 0;
mac_free(label);
if (error != 0) {
syslog(LOG_ERR, "mac_set_proc('%s') for %s: %s",
label_string, pwd->pw_name, strerror(error));
return (-1);
}
}
}
/* Set the sessions login */
if ((flags & LOGIN_SETLOGIN) && setlogin(pwd->pw_name) != 0) {
syslog(LOG_ERR, "setlogin(%s): %m", pwd->pw_name);
login_close(llc);
return (-1);
}
/* Inform the kernel about current login class */
if (lc != NULL && lc->lc_class != NULL && (flags & LOGIN_SETLOGINCLASS)) {
/*
* XXX: This is a workaround to fail gracefully in case the kernel
* does not support setloginclass(2).
*/
bzero(&sa, sizeof(sa));
sa.sa_handler = SIG_IGN;
sigfillset(&sa.sa_mask);
sigaction(SIGSYS, &sa, &prevsa);
error = setloginclass(lc->lc_class);
sigaction(SIGSYS, &prevsa, NULL);
if (error != 0) {
syslog(LOG_ERR, "setloginclass(%s): %m", lc->lc_class);
#ifdef notyet
login_close(llc);
return (-1);
#endif
}
}
mymask = (flags & LOGIN_SETUMASK) ? umask(LOGIN_DEFUMASK) : 0;
mymask = setlogincontext(lc, pwd, mymask, flags);
login_close(llc);
/* This needs to be done after anything that needs root privs */
if ((flags & LOGIN_SETUSER) && setuid(uid) != 0) {
syslog(LOG_ERR, "setuid(%lu): %m", (u_long)uid);
return (-1); /* Paranoia again */
}
/*
* Now, we repeat some of the above for the user's private entries
*/
if (getuid() == uid && (lc = login_getuserclass(pwd)) != NULL) {
mymask = setlogincontext(lc, pwd, mymask, flags);
login_close(lc);
}
/* Finally, set any umask we've found */
if (flags & LOGIN_SETUMASK)
umask(mymask);
return (0);
}
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