The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_loginclass.c

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    1 /*-
    2  * Copyright (c) 2011 The FreeBSD Foundation
    3  * All rights reserved.
    4  *
    5  * This software was developed by Edward Tomasz Napierala under sponsorship
    6  * from the FreeBSD Foundation.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, 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  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  * $FreeBSD: releng/11.1/sys/kern/kern_loginclass.c 290857 2015-11-15 12:10:51Z trasz $
   30  */
   31 
   32 /*
   33  * Processes may set login class name using setloginclass(2).  This
   34  * is usually done through call to setusercontext(3), by programs
   35  * such as login(1), based on information from master.passwd(5).  Kernel
   36  * uses this information to enforce per-class resource limits.  Current
   37  * login class can be determined using id(1).  Login class is inherited
   38  * from the parent process during fork(2).  If not set, it defaults
   39  * to "default".
   40  *
   41  * Code in this file implements setloginclass(2) and getloginclass(2)
   42  * system calls, and maintains class name storage and retrieval.
   43  */
   44 
   45 #include <sys/cdefs.h>
   46 __FBSDID("$FreeBSD: releng/11.1/sys/kern/kern_loginclass.c 290857 2015-11-15 12:10:51Z trasz $");
   47 
   48 #include <sys/param.h>
   49 #include <sys/eventhandler.h>
   50 #include <sys/kernel.h>
   51 #include <sys/lock.h>
   52 #include <sys/loginclass.h>
   53 #include <sys/malloc.h>
   54 #include <sys/types.h>
   55 #include <sys/priv.h>
   56 #include <sys/proc.h>
   57 #include <sys/queue.h>
   58 #include <sys/racct.h>
   59 #include <sys/refcount.h>
   60 #include <sys/rwlock.h>
   61 #include <sys/sysproto.h>
   62 #include <sys/systm.h>
   63 
   64 static MALLOC_DEFINE(M_LOGINCLASS, "loginclass", "loginclass structures");
   65 
   66 LIST_HEAD(, loginclass) loginclasses;
   67 
   68 /*
   69  * Lock protecting loginclasses list.
   70  */
   71 static struct rwlock loginclasses_lock;
   72 RW_SYSINIT(loginclasses_init, &loginclasses_lock, "loginclasses lock");
   73 
   74 void
   75 loginclass_hold(struct loginclass *lc)
   76 {
   77 
   78         refcount_acquire(&lc->lc_refcount);
   79 }
   80 
   81 void
   82 loginclass_free(struct loginclass *lc)
   83 {
   84         int old;
   85 
   86         old = lc->lc_refcount;
   87         if (old > 1 && atomic_cmpset_int(&lc->lc_refcount, old, old - 1))
   88                 return;
   89 
   90         rw_wlock(&loginclasses_lock);
   91         if (!refcount_release(&lc->lc_refcount)) {
   92                 rw_wunlock(&loginclasses_lock);
   93                 return;
   94         }
   95 
   96         racct_destroy(&lc->lc_racct);
   97         LIST_REMOVE(lc, lc_next);
   98         rw_wunlock(&loginclasses_lock);
   99 
  100         free(lc, M_LOGINCLASS);
  101 }
  102 
  103 /*
  104  * Look up a loginclass struct for the parameter name.
  105  * loginclasses_lock must be locked.
  106  * Increase refcount on loginclass struct returned.
  107  */
  108 static struct loginclass *
  109 loginclass_lookup(const char *name)
  110 {
  111         struct loginclass *lc;
  112 
  113         rw_assert(&loginclasses_lock, RA_LOCKED);
  114         LIST_FOREACH(lc, &loginclasses, lc_next)
  115                 if (strcmp(name, lc->lc_name) == 0) {
  116                         loginclass_hold(lc);
  117                         break;
  118                 }
  119 
  120         return (lc);
  121 }
  122 
  123 /*
  124  * Return loginclass structure with a corresponding name.  Not
  125  * performance critical, as it's used mainly by setloginclass(2),
  126  * which happens once per login session.  Caller has to use
  127  * loginclass_free() on the returned value when it's no longer
  128  * needed.
  129  */
  130 struct loginclass *
  131 loginclass_find(const char *name)
  132 {
  133         struct loginclass *lc, *new_lc;
  134 
  135         if (name[0] == '\0' || strlen(name) >= MAXLOGNAME)
  136                 return (NULL);
  137 
  138         rw_rlock(&loginclasses_lock);
  139         lc = loginclass_lookup(name);
  140         rw_runlock(&loginclasses_lock);
  141         if (lc != NULL)
  142                 return (lc);
  143 
  144         new_lc = malloc(sizeof(*new_lc), M_LOGINCLASS, M_ZERO | M_WAITOK);
  145         racct_create(&new_lc->lc_racct);
  146         refcount_init(&new_lc->lc_refcount, 1);
  147         strcpy(new_lc->lc_name, name);
  148 
  149         rw_wlock(&loginclasses_lock);
  150         /*
  151          * There's a chance someone created our loginclass while we
  152          * were in malloc and not holding the lock, so we have to
  153          * make sure we don't insert a duplicate loginclass.
  154          */
  155         if ((lc = loginclass_lookup(name)) == NULL) {
  156                 LIST_INSERT_HEAD(&loginclasses, new_lc, lc_next);
  157                 rw_wunlock(&loginclasses_lock);
  158                 lc = new_lc;
  159         } else {
  160                 rw_wunlock(&loginclasses_lock);
  161                 racct_destroy(&new_lc->lc_racct);
  162                 free(new_lc, M_LOGINCLASS);
  163         }
  164 
  165         return (lc);
  166 }
  167 
  168 /*
  169  * Get login class name.
  170  */
  171 #ifndef _SYS_SYSPROTO_H_
  172 struct getloginclass_args {
  173         char    *namebuf;
  174         size_t  namelen;
  175 };
  176 #endif
  177 /* ARGSUSED */
  178 int
  179 sys_getloginclass(struct thread *td, struct getloginclass_args *uap)
  180 {
  181         struct loginclass *lc;
  182         size_t lcnamelen;
  183 
  184         lc = td->td_ucred->cr_loginclass;
  185         lcnamelen = strlen(lc->lc_name) + 1;
  186         if (lcnamelen > uap->namelen)
  187                 return (ERANGE);
  188         return (copyout(lc->lc_name, uap->namebuf, lcnamelen));
  189 }
  190 
  191 /*
  192  * Set login class name.
  193  */
  194 #ifndef _SYS_SYSPROTO_H_
  195 struct setloginclass_args {
  196         const char      *namebuf;
  197 };
  198 #endif
  199 /* ARGSUSED */
  200 int
  201 sys_setloginclass(struct thread *td, struct setloginclass_args *uap)
  202 {
  203         struct proc *p = td->td_proc;
  204         int error;
  205         char lcname[MAXLOGNAME];
  206         struct loginclass *newlc;
  207         struct ucred *newcred, *oldcred;
  208 
  209         error = priv_check(td, PRIV_PROC_SETLOGINCLASS);
  210         if (error != 0)
  211                 return (error);
  212         error = copyinstr(uap->namebuf, lcname, sizeof(lcname), NULL);
  213         if (error != 0)
  214                 return (error);
  215 
  216         newlc = loginclass_find(lcname);
  217         if (newlc == NULL)
  218                 return (EINVAL);
  219         newcred = crget();
  220 
  221         PROC_LOCK(p);
  222         oldcred = crcopysafe(p, newcred);
  223         newcred->cr_loginclass = newlc;
  224         proc_set_cred(p, newcred);
  225         PROC_UNLOCK(p);
  226 #ifdef RACCT
  227         racct_proc_ucred_changed(p, oldcred, newcred);
  228 #endif
  229         loginclass_free(oldcred->cr_loginclass);
  230         crfree(oldcred);
  231 
  232         return (0);
  233 }
  234 
  235 void
  236 loginclass_racct_foreach(void (*callback)(struct racct *racct,
  237     void *arg2, void *arg3), void (*pre)(void), void (*post)(void),
  238     void *arg2, void *arg3)
  239 {
  240         struct loginclass *lc;
  241 
  242         rw_rlock(&loginclasses_lock);
  243         if (pre != NULL)
  244                 (pre)();
  245         LIST_FOREACH(lc, &loginclasses, lc_next)
  246                 (callback)(lc->lc_racct, arg2, arg3);
  247         if (post != NULL)
  248                 (post)();
  249         rw_runlock(&loginclasses_lock);
  250 }

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