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/9.1/sys/kern/kern_loginclass.c 225617 2011-09-16 13:58:51Z kmacy $
   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/9.1/sys/kern/kern_loginclass.c 225617 2011-09-16 13:58:51Z kmacy $");
   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 
   73 static void lc_init(void);
   74 SYSINIT(loginclass, SI_SUB_CPU, SI_ORDER_FIRST, lc_init, NULL);
   75 
   76 void
   77 loginclass_hold(struct loginclass *lc)
   78 {
   79 
   80         refcount_acquire(&lc->lc_refcount);
   81 }
   82 
   83 void
   84 loginclass_free(struct loginclass *lc)
   85 {
   86         int old;
   87 
   88         old = lc->lc_refcount;
   89         if (old > 1 && atomic_cmpset_int(&lc->lc_refcount, old, old - 1))
   90                 return;
   91 
   92         mtx_lock(&loginclasses_lock);
   93         if (refcount_release(&lc->lc_refcount)) {
   94                 racct_destroy(&lc->lc_racct);
   95                 LIST_REMOVE(lc, lc_next);
   96                 mtx_unlock(&loginclasses_lock);
   97                 free(lc, M_LOGINCLASS);
   98 
   99                 return;
  100         }
  101         mtx_unlock(&loginclasses_lock);
  102 }
  103 
  104 /*
  105  * Return loginclass structure with a corresponding name.  Not
  106  * performance critical, as it's used mainly by setloginclass(2),
  107  * which happens once per login session.  Caller has to use
  108  * loginclass_free() on the returned value when it's no longer
  109  * needed.
  110  */
  111 struct loginclass *
  112 loginclass_find(const char *name)
  113 {
  114         struct loginclass *lc, *newlc;
  115 
  116         if (name[0] == '\0' || strlen(name) >= MAXLOGNAME)
  117                 return (NULL);
  118 
  119         newlc = malloc(sizeof(*newlc), M_LOGINCLASS, M_ZERO | M_WAITOK);
  120         racct_create(&newlc->lc_racct);
  121 
  122         mtx_lock(&loginclasses_lock);
  123         LIST_FOREACH(lc, &loginclasses, lc_next) {
  124                 if (strcmp(name, lc->lc_name) != 0)
  125                         continue;
  126 
  127                 /* Found loginclass with a matching name? */
  128                 loginclass_hold(lc);
  129                 mtx_unlock(&loginclasses_lock);
  130                 racct_destroy(&newlc->lc_racct);
  131                 free(newlc, M_LOGINCLASS);
  132                 return (lc);
  133         }
  134 
  135         /* Add new loginclass. */
  136         strcpy(newlc->lc_name, name);
  137         refcount_init(&newlc->lc_refcount, 1);
  138         LIST_INSERT_HEAD(&loginclasses, newlc, lc_next);
  139         mtx_unlock(&loginclasses_lock);
  140 
  141         return (newlc);
  142 }
  143 
  144 /*
  145  * Get login class name.
  146  */
  147 #ifndef _SYS_SYSPROTO_H_
  148 struct getloginclass_args {
  149         char    *namebuf;
  150         size_t  namelen;
  151 };
  152 #endif
  153 /* ARGSUSED */
  154 int
  155 sys_getloginclass(struct thread *td, struct getloginclass_args *uap)
  156 {
  157         int error = 0;
  158         size_t lcnamelen;
  159         struct proc *p;
  160         struct loginclass *lc;
  161 
  162         p = td->td_proc;
  163         PROC_LOCK(p);
  164         lc = p->p_ucred->cr_loginclass;
  165         loginclass_hold(lc);
  166         PROC_UNLOCK(p);
  167 
  168         lcnamelen = strlen(lc->lc_name) + 1;
  169         if (lcnamelen > uap->namelen)
  170                 error = ERANGE;
  171         if (error == 0)
  172                 error = copyout(lc->lc_name, uap->namebuf, lcnamelen);
  173         loginclass_free(lc);
  174         return (error);
  175 }
  176 
  177 /*
  178  * Set login class name.
  179  */
  180 #ifndef _SYS_SYSPROTO_H_
  181 struct setloginclass_args {
  182         const char      *namebuf;
  183 };
  184 #endif
  185 /* ARGSUSED */
  186 int
  187 sys_setloginclass(struct thread *td, struct setloginclass_args *uap)
  188 {
  189         struct proc *p = td->td_proc;
  190         int error;
  191         char lcname[MAXLOGNAME];
  192         struct loginclass *newlc;
  193         struct ucred *newcred, *oldcred;
  194 
  195         error = priv_check(td, PRIV_PROC_SETLOGINCLASS);
  196         if (error != 0)
  197                 return (error);
  198         error = copyinstr(uap->namebuf, lcname, sizeof(lcname), NULL);
  199         if (error != 0)
  200                 return (error);
  201 
  202         newlc = loginclass_find(lcname);
  203         if (newlc == NULL)
  204                 return (EINVAL);
  205         newcred = crget();
  206 
  207         PROC_LOCK(p);
  208         oldcred = crcopysafe(p, newcred);
  209         newcred->cr_loginclass = newlc;
  210         p->p_ucred = newcred;
  211         PROC_UNLOCK(p);
  212 #ifdef RACCT
  213         racct_proc_ucred_changed(p, oldcred, newcred);
  214 #endif
  215         loginclass_free(oldcred->cr_loginclass);
  216         crfree(oldcred);
  217 
  218         return (0);
  219 }
  220 
  221 void
  222 loginclass_racct_foreach(void (*callback)(struct racct *racct,
  223     void *arg2, void *arg3), void *arg2, void *arg3)
  224 {
  225         struct loginclass *lc;
  226 
  227         mtx_lock(&loginclasses_lock);
  228         LIST_FOREACH(lc, &loginclasses, lc_next)
  229                 (callback)(lc->lc_racct, arg2, arg3);
  230         mtx_unlock(&loginclasses_lock);
  231 }
  232 
  233 static void
  234 lc_init(void)
  235 {
  236 
  237         mtx_init(&loginclasses_lock, "loginclasses lock", NULL, MTX_DEF);
  238 }

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