common/os/session.c

	session.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */


#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sys/types.h>
#include <sys/sysmacros.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/file.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/errno.h>
#include <sys/signal.h>
#include <sys/pcb.h>
#include <sys/cred.h>
#include <sys/policy.h>
#include <sys/user.h>
#include <sys/buf.h>
#include <sys/var.h>
#include <sys/conf.h>
#include <sys/debug.h>
#include <sys/proc.h>
#include <sys/session.h>
#include <sys/kmem.h>
#include <sys/cmn_err.h>
#include <sys/strsubr.h>

sess_t session0 = {
    1,  /* s_ref   */
    0555,   /* s_mode  */
    0,  /* s_uid   */
    0,  /* s_gid   */
    0,  /* s_ctime */
    NODEV,  /* s_dev   */
    NULL,   /* s_vp    */
    &pid0,  /* s_sidp  */
    NULL    /* s_cred  */
};

void
sess_rele(sess_t *sp)
{
    ASSERT(MUTEX_HELD(&pidlock));

    ASSERT(sp->s_ref != 0);
    if (--sp->s_ref == 0) {
        if (sp == &session0)
            panic("sp == &session0");
        PID_RELE(sp->s_sidp);
        mutex_destroy(&sp->s_lock);
        cv_destroy(&sp->s_wait_cv);
        kmem_free(sp, sizeof (sess_t));
    }
}

void
sess_create(void)
{
    proc_t *pp;
    sess_t *sp;

    pp = ttoproc(curthread);

    sp = kmem_zalloc(sizeof (sess_t), KM_SLEEP);

    mutex_init(&sp->s_lock, NULL, MUTEX_DEFAULT, NULL);
    cv_init(&sp->s_wait_cv, NULL, CV_DEFAULT, NULL);

    mutex_enter(&pidlock);

    /*
     * We need to protect p_pgidp with p_lock because
     * /proc looks at it while holding only p_lock.
     */
    mutex_enter(&pp->p_lock);
    pgexit(pp);
    SESS_RELE(pp->p_sessp);

    sp->s_sidp = pp->p_pidp;
    sp->s_ref = 1;
    sp->s_dev = NODEV;

    pp->p_sessp = sp;

    pgjoin(pp, pp->p_pidp);
    mutex_exit(&pp->p_lock);

    PID_HOLD(sp->s_sidp);
    mutex_exit(&pidlock);
}

void
freectty(sess_t *sp)
{
    vnode_t *vp;
    cred_t *cred;

    vp = sp->s_vp;

    strfreectty(vp->v_stream);

    mutex_enter(&sp->s_lock);
    while (sp->s_cnt > 0) {
        cv_wait(&sp->s_wait_cv, &sp->s_lock);
    }
    ASSERT(sp->s_cnt == 0);
    ASSERT(vp->v_count >= 1);
    sp->s_vp = NULL;
    cred = sp->s_cred;

    /*
     * It is possible for the VOP_CLOSE below to call strctty
     * and reallocate a new tty vnode.  To prevent that the
     * session is marked as closing here.
     */

    sp->s_flag = SESS_CLOSE;
    sp->s_cred = NULL;
    mutex_exit(&sp->s_lock);

    /*
     * This will be the only thread with access to
     * this vnode, from this point on.
     */

    (void) VOP_CLOSE(vp, 0, 1, (offset_t)0, cred);
    VN_RELE(vp);

    crfree(cred);
}

/*
 *  ++++++++++++++++++++++++
 *  ++  SunOS4.1 Buyback  ++
 *  ++++++++++++++++++++++++
 *
 * vhangup: Revoke access of the current tty by all processes
 * Used by privileged users to give a "clean" terminal at login
 */
int
vhangup()
{
    if (secpolicy_sys_config(CRED(), B_FALSE) != 0)
        return (set_errno(EPERM));
    /*
     * This routine used to call freectty() under a condition that
     * could never happen.  So this code has never actually done
     * anything, and evidently nobody has ever noticed.  4098399.
     */
    return (0);
}

dev_t
cttydev(proc_t *pp)
{
    sess_t *sp = pp->p_sessp;
    if (sp->s_vp == NULL)
        return (NODEV);
    return (sp->s_dev);
}

void
alloctty(proc_t *pp, vnode_t *vp)
{
    sess_t *sp = pp->p_sessp;
    cred_t *crp;

    sp->s_vp = vp;
    sp->s_dev = vp->v_rdev;

    mutex_enter(&pp->p_crlock);
    crhold(crp = pp->p_cred);
    mutex_exit(&pp->p_crlock);
    sp->s_cred = crp;
    sp->s_uid = crgetuid(crp);
    sp->s_ctime = gethrestime_sec();
    if (session0.s_mode & VSGID)
        sp->s_gid = session0.s_gid;
    else
        sp->s_gid = crgetgid(crp);
    sp->s_mode = (0666 & ~(PTOU(pp)->u_cmask));
}

int
hascttyperm(sess_t *sp, cred_t *cr, mode_t mode)
{
    int shift = 0;

    if (crgetuid(cr) != sp->s_uid) {
        shift += 3;
        if (!groupmember(sp->s_gid, cr))
            shift += 3;
    }

    mode &= ~(sp->s_mode << shift);

    if (mode == 0)
        return (1);

    return (secpolicy_vnode_access(cr, sp->s_vp, sp->s_uid, mode) == 0);
}