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/10.2/sys/kern/kern_loginclass.c 267579 2014-06-17 13:14:31Z 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/10.2/sys/kern/kern_loginclass.c 267579 2014-06-17 13:14:31Z 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/mutex.h>
   55 #include <sys/types.h>
   56 #include <sys/priv.h>
   57 #include <sys/proc.h>
   58 #include <sys/queue.h>
   59 #include <sys/racct.h>
   60 #include <sys/refcount.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 mtx loginclasses_lock;
   72 MTX_SYSINIT(loginclasses_init, &loginclasses_lock, "loginclasses lock", MTX_DEF);
   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         mtx_lock(&loginclasses_lock);
   91         if (refcount_release(&lc->lc_refcount)) {
   92                 racct_destroy(&lc->lc_racct);
   93                 LIST_REMOVE(lc, lc_next);
   94                 mtx_unlock(&loginclasses_lock);
   95                 free(lc, M_LOGINCLASS);
   96 
   97                 return;
   98         }
   99         mtx_unlock(&loginclasses_lock);
  100 }
  101 
  102 /*
  103  * Return loginclass structure with a corresponding name.  Not
  104  * performance critical, as it's used mainly by setloginclass(2),
  105  * which happens once per login session.  Caller has to use
  106  * loginclass_free() on the returned value when it's no longer
  107  * needed.
  108  */
  109 struct loginclass *
  110 loginclass_find(const char *name)
  111 {
  112         struct loginclass *lc, *newlc;
  113 
  114         if (name[0] == '\0' || strlen(name) >= MAXLOGNAME)
  115                 return (NULL);
  116 
  117         newlc = malloc(sizeof(*newlc), M_LOGINCLASS, M_ZERO | M_WAITOK);
  118         racct_create(&newlc->lc_racct);
  119 
  120         mtx_lock(&loginclasses_lock);
  121         LIST_FOREACH(lc, &loginclasses, lc_next) {
  122                 if (strcmp(name, lc->lc_name) != 0)
  123                         continue;
  124 
  125                 /* Found loginclass with a matching name? */
  126                 loginclass_hold(lc);
  127                 mtx_unlock(&loginclasses_lock);
  128                 racct_destroy(&newlc->lc_racct);
  129                 free(newlc, M_LOGINCLASS);
  130                 return (lc);
  131         }
  132 
  133         /* Add new loginclass. */
  134         strcpy(newlc->lc_name, name);
  135         refcount_init(&newlc->lc_refcount, 1);
  136         LIST_INSERT_HEAD(&loginclasses, newlc, lc_next);
  137         mtx_unlock(&loginclasses_lock);
  138 
  139         return (newlc);
  140 }
  141 
  142 /*
  143  * Get login class name.
  144  */
  145 #ifndef _SYS_SYSPROTO_H_
  146 struct getloginclass_args {
  147         char    *namebuf;
  148         size_t  namelen;
  149 };
  150 #endif
  151 /* ARGSUSED */
  152 int
  153 sys_getloginclass(struct thread *td, struct getloginclass_args *uap)
  154 {
  155         int error = 0;
  156         size_t lcnamelen;
  157         struct proc *p;
  158         struct loginclass *lc;
  159 
  160         p = td->td_proc;
  161         PROC_LOCK(p);
  162         lc = p->p_ucred->cr_loginclass;
  163         loginclass_hold(lc);
  164         PROC_UNLOCK(p);
  165 
  166         lcnamelen = strlen(lc->lc_name) + 1;
  167         if (lcnamelen > uap->namelen)
  168                 error = ERANGE;
  169         if (error == 0)
  170                 error = copyout(lc->lc_name, uap->namebuf, lcnamelen);
  171         loginclass_free(lc);
  172         return (error);
  173 }
  174 
  175 /*
  176  * Set login class name.
  177  */
  178 #ifndef _SYS_SYSPROTO_H_
  179 struct setloginclass_args {
  180         const char      *namebuf;
  181 };
  182 #endif
  183 /* ARGSUSED */
  184 int
  185 sys_setloginclass(struct thread *td, struct setloginclass_args *uap)
  186 {
  187         struct proc *p = td->td_proc;
  188         int error;
  189         char lcname[MAXLOGNAME];
  190         struct loginclass *newlc;
  191         struct ucred *newcred, *oldcred;
  192 
  193         error = priv_check(td, PRIV_PROC_SETLOGINCLASS);
  194         if (error != 0)
  195                 return (error);
  196         error = copyinstr(uap->namebuf, lcname, sizeof(lcname), NULL);
  197         if (error != 0)
  198                 return (error);
  199 
  200         newlc = loginclass_find(lcname);
  201         if (newlc == NULL)
  202                 return (EINVAL);
  203         newcred = crget();
  204 
  205         PROC_LOCK(p);
  206         oldcred = crcopysafe(p, newcred);
  207         newcred->cr_loginclass = newlc;
  208         p->p_ucred = newcred;
  209         PROC_UNLOCK(p);
  210 #ifdef RACCT
  211         racct_proc_ucred_changed(p, oldcred, newcred);
  212 #endif
  213         loginclass_free(oldcred->cr_loginclass);
  214         crfree(oldcred);
  215 
  216         return (0);
  217 }
  218 
  219 void
  220 loginclass_racct_foreach(void (*callback)(struct racct *racct,
  221     void *arg2, void *arg3), void *arg2, void *arg3)
  222 {
  223         struct loginclass *lc;
  224 
  225         mtx_lock(&loginclasses_lock);
  226         LIST_FOREACH(lc, &loginclasses, lc_next)
  227                 (callback)(lc->lc_racct, arg2, arg3);
  228         mtx_unlock(&loginclasses_lock);
  229 }

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