201 lines
5.0 KiB
C
201 lines
5.0 KiB
C
/*
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*
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* Copyright 1999 Digi International (www.digi.com)
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* James Puzzo <jamesp at digi dot com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED; without even the
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* implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU General Public License for more details.
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*
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*/
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/*
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*
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* Filename:
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*
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* dgrp_common.c
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*
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* Description:
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*
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* Definitions of global variables and functions which are either
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* shared by the tty, mon, and net drivers; or which cross them
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* functionally (like the poller).
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*
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* Author:
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*
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* James A. Puzzo
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*
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*/
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#include <linux/errno.h>
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#include <linux/tty.h>
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#include <linux/sched.h>
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#include <linux/cred.h>
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#include "dgrp_common.h"
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/**
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* dgrp_carrier -- check for carrier change state and act
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* @ch: struct ch_struct *
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*/
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void dgrp_carrier(struct ch_struct *ch)
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{
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struct nd_struct *nd;
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int virt_carrier = 0;
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int phys_carrier = 0;
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/* fix case when the tty has already closed. */
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if (!ch)
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return;
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nd = ch->ch_nd;
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if (!nd)
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return;
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/*
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* If we are currently waiting to determine the status of the port,
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* we don't yet know the state of the modem lines. As a result,
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* we ignore state changes when we are waiting for the modem lines
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* to be established. We know, as a result of code in dgrp_net_ops,
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* that we will be called again immediately following the reception
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* of the status message with the true modem status flags in it.
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*/
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if (ch->ch_expect & RR_STATUS)
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return;
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/*
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* If CH_HANGUP is set, we gotta keep trying to get all the processes
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* that have the port open to close the port.
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* So lets just keep sending a hangup every time we get here.
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*/
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if ((ch->ch_flag & CH_HANGUP) &&
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(ch->ch_tun.un_open_count > 0))
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tty_hangup(ch->ch_tun.un_tty);
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/*
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* Compute the effective state of both the physical and virtual
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* senses of carrier.
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*/
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if (ch->ch_s_mlast & DM_CD)
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phys_carrier = 1;
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if ((ch->ch_s_mlast & DM_CD) ||
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(ch->ch_digi.digi_flags & DIGI_FORCEDCD) ||
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(ch->ch_flag & CH_CLOCAL))
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virt_carrier = 1;
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/*
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* Test for a VIRTUAL carrier transition to HIGH.
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*
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* The CH_HANGUP condition is intended to prevent any action
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* except for close. As a result, we ignore positive carrier
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* transitions during CH_HANGUP.
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*/
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if (((ch->ch_flag & CH_HANGUP) == 0) &&
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((ch->ch_flag & CH_VIRT_CD) == 0) &&
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(virt_carrier == 1)) {
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/*
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* When carrier rises, wake any threads waiting
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* for carrier in the open routine.
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*/
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nd->nd_tx_work = 1;
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if (waitqueue_active(&ch->ch_flag_wait))
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wake_up_interruptible(&ch->ch_flag_wait);
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}
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/*
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* Test for a PHYSICAL transition to low, so long as we aren't
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* currently ignoring physical transitions (which is what "virtual
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* carrier" indicates).
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*
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* The transition of the virtual carrier to low really doesn't
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* matter... it really only means "ignore carrier state", not
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* "make pretend that carrier is there".
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*/
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if ((virt_carrier == 0) &&
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((ch->ch_flag & CH_PHYS_CD) != 0) &&
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(phys_carrier == 0)) {
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/*
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* When carrier drops:
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*
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* Do a Hard Hangup if that is called for.
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*
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* Drop carrier on all open units.
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*
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* Flush queues, waking up any task waiting in the
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* line discipline.
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*
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* Send a hangup to the control terminal.
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*
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* Enable all select calls.
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*/
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nd->nd_tx_work = 1;
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ch->ch_flag &= ~(CH_LOW | CH_EMPTY | CH_DRAIN | CH_INPUT);
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if (waitqueue_active(&ch->ch_flag_wait))
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wake_up_interruptible(&ch->ch_flag_wait);
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if (ch->ch_tun.un_open_count > 0)
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tty_hangup(ch->ch_tun.un_tty);
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if (ch->ch_pun.un_open_count > 0)
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tty_hangup(ch->ch_pun.un_tty);
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}
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/*
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* Make sure that our cached values reflect the current reality.
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*/
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if (virt_carrier == 1)
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ch->ch_flag |= CH_VIRT_CD;
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else
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ch->ch_flag &= ~CH_VIRT_CD;
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if (phys_carrier == 1)
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ch->ch_flag |= CH_PHYS_CD;
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else
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ch->ch_flag &= ~CH_PHYS_CD;
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}
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/**
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* dgrp_chk_perm() -- check permissions for net device
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* @inode: pointer to inode structure for the net communication device
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* @op: operation to be tested
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*
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* The file permissions and ownerships are tested to determine whether
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* the operation "op" is permitted on the file pointed to by the inode.
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* Returns 0 if the operation is permitted, -EACCESS otherwise
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*/
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int dgrp_chk_perm(int mode, int op)
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{
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if (!uid_eq(GLOBAL_ROOT_UID, current_euid()))
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mode >>= 6;
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else if (in_egroup_p(GLOBAL_ROOT_GID))
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mode >>= 3;
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if ((mode & op & 0007) == op)
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return 0;
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if (capable(CAP_SYS_ADMIN))
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return 0;
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return -EACCES;
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}
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/* dgrp_chk_perm wrapper for permission call in struct inode_operations */
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int dgrp_inode_permission(struct inode *inode, int op)
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{
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return dgrp_chk_perm(inode->i_mode, op);
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}
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