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freebsd-dev/lib/libutil/login_class.c
Ed Schouten bc093719ca Integrate the new MPSAFE TTY layer to the FreeBSD operating system. 
The last half year I've been working on a replacement TTY layer for the
FreeBSD kernel. The new TTY layer was designed to improve the following:

- Improved driver model:

  The old TTY layer has a driver model that is not abstract enough to
  make it friendly to use. A good example is the output path, where the
  device drivers directly access the output buffers. This means that an
  in-kernel PPP implementation must always convert network buffers into
  TTY buffers.

  If a PPP implementation would be built on top of the new TTY layer
  (still needs a hooks layer, though), it would allow the PPP
  implementation to directly hand the data to the TTY driver.

- Improved hotplugging:

  With the old TTY layer, it isn't entirely safe to destroy TTY's from
  the system. This implementation has a two-step destructing design,
  where the driver first abandons the TTY. After all threads have left
  the TTY, the TTY layer calls a routine in the driver, which can be
  used to free resources (unit numbers, etc).

  The pts(4) driver also implements this feature, which means
  posix_openpt() will now return PTY's that are created on the fly.

- Improved performance:

  One of the major improvements is the per-TTY mutex, which is expected
  to improve scalability when compared to the old Giant locking.
  Another change is the unbuffered copying to userspace, which is both
  used on TTY device nodes and PTY masters.

Upgrading should be quite straightforward. Unlike previous versions,
existing kernel configuration files do not need to be changed, except
when they reference device drivers that are listed in UPDATING.

Obtained from:		//depot/projects/mpsafetty/...
Approved by:		philip (ex-mentor)
Discussed:		on the lists, at BSDCan, at the DevSummit
Sponsored by:		Snow B.V., the Netherlands
dcons(4) fixed by:	kan
2008-08-20 08:31:58 +00:00

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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/types.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/cpuset.h>
#include <sys/mac.h>
#include <sys/rtprio.h>
#include <errno.h>
#include <fcntl.h>
#include <login_cap.h>
#include <paths.h>
#include <pwd.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 },
{ 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;
if (pwd != NULL) {
/* Count the number of ~'s in var to substitute */
for (p = (char *)var; (p = strchr(p, '~')) != NULL; p++)
++tildes;
/* Count the number of $'s in var to substitute */
for (p = (char *)var; (p = strchr(p, '$')) != NULL; p++)
++dollas;
}
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 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->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->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->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;
}
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 ((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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