![Linus Torvalds](/assets/img/avatar_default.png)
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
804 lines
18 KiB
C
804 lines
18 KiB
C
/*
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* PPP synchronous tty channel driver for Linux.
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*
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* This is a ppp channel driver that can be used with tty device drivers
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* that are frame oriented, such as synchronous HDLC devices.
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*
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* Complete PPP frames without encoding/decoding are exchanged between
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* the channel driver and the device driver.
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*
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* The async map IOCTL codes are implemented to keep the user mode
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* applications happy if they call them. Synchronous PPP does not use
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* the async maps.
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*
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* Copyright 1999 Paul Mackerras.
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*
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* Also touched by the grubby hands of Paul Fulghum paulkf@microgate.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* This driver provides the encapsulation and framing for sending
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* and receiving PPP frames over sync serial lines. It relies on
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* the generic PPP layer to give it frames to send and to process
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* received frames. It implements the PPP line discipline.
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*
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* Part of the code in this driver was inspired by the old async-only
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* PPP driver, written by Michael Callahan and Al Longyear, and
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* subsequently hacked by Paul Mackerras.
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*
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* ==FILEVERSION 20040616==
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/tty.h>
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#include <linux/netdevice.h>
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#include <linux/poll.h>
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#include <linux/ppp_defs.h>
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#include <linux/if_ppp.h>
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#include <linux/ppp_channel.h>
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#include <linux/spinlock.h>
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#include <linux/init.h>
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#include <asm/uaccess.h>
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#include <asm/semaphore.h>
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#define PPP_VERSION "2.4.2"
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/* Structure for storing local state. */
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struct syncppp {
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struct tty_struct *tty;
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unsigned int flags;
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unsigned int rbits;
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int mru;
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spinlock_t xmit_lock;
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spinlock_t recv_lock;
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unsigned long xmit_flags;
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u32 xaccm[8];
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u32 raccm;
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unsigned int bytes_sent;
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unsigned int bytes_rcvd;
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struct sk_buff *tpkt;
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unsigned long last_xmit;
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struct sk_buff_head rqueue;
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struct tasklet_struct tsk;
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atomic_t refcnt;
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struct semaphore dead_sem;
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struct ppp_channel chan; /* interface to generic ppp layer */
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};
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/* Bit numbers in xmit_flags */
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#define XMIT_WAKEUP 0
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#define XMIT_FULL 1
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/* Bits in rbits */
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#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
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#define PPPSYNC_MAX_RQLEN 32 /* arbitrary */
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/*
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* Prototypes.
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*/
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static struct sk_buff* ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *);
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static int ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb);
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static int ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd,
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unsigned long arg);
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static void ppp_sync_process(unsigned long arg);
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static int ppp_sync_push(struct syncppp *ap);
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static void ppp_sync_flush_output(struct syncppp *ap);
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static void ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
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char *flags, int count);
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static struct ppp_channel_ops sync_ops = {
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ppp_sync_send,
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ppp_sync_ioctl
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};
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/*
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* Utility procedures to print a buffer in hex/ascii
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*/
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static void
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ppp_print_hex (register __u8 * out, const __u8 * in, int count)
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{
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register __u8 next_ch;
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static char hex[] = "0123456789ABCDEF";
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while (count-- > 0) {
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next_ch = *in++;
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*out++ = hex[(next_ch >> 4) & 0x0F];
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*out++ = hex[next_ch & 0x0F];
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++out;
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}
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}
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static void
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ppp_print_char (register __u8 * out, const __u8 * in, int count)
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{
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register __u8 next_ch;
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while (count-- > 0) {
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next_ch = *in++;
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if (next_ch < 0x20 || next_ch > 0x7e)
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*out++ = '.';
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else {
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*out++ = next_ch;
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if (next_ch == '%') /* printk/syslogd has a bug !! */
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*out++ = '%';
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}
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}
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*out = '\0';
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}
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static void
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ppp_print_buffer (const char *name, const __u8 *buf, int count)
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{
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__u8 line[44];
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if (name != NULL)
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printk(KERN_DEBUG "ppp_synctty: %s, count = %d\n", name, count);
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while (count > 8) {
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memset (line, 32, 44);
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ppp_print_hex (line, buf, 8);
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ppp_print_char (&line[8 * 3], buf, 8);
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printk(KERN_DEBUG "%s\n", line);
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count -= 8;
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buf += 8;
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}
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if (count > 0) {
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memset (line, 32, 44);
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ppp_print_hex (line, buf, count);
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ppp_print_char (&line[8 * 3], buf, count);
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printk(KERN_DEBUG "%s\n", line);
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}
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}
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/*
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* Routines implementing the synchronous PPP line discipline.
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*/
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/*
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* We have a potential race on dereferencing tty->disc_data,
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* because the tty layer provides no locking at all - thus one
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* cpu could be running ppp_synctty_receive while another
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* calls ppp_synctty_close, which zeroes tty->disc_data and
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* frees the memory that ppp_synctty_receive is using. The best
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* way to fix this is to use a rwlock in the tty struct, but for now
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* we use a single global rwlock for all ttys in ppp line discipline.
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*
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* FIXME: Fixed in tty_io nowdays.
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*/
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static DEFINE_RWLOCK(disc_data_lock);
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static struct syncppp *sp_get(struct tty_struct *tty)
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{
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struct syncppp *ap;
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read_lock(&disc_data_lock);
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ap = tty->disc_data;
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if (ap != NULL)
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atomic_inc(&ap->refcnt);
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read_unlock(&disc_data_lock);
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return ap;
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}
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static void sp_put(struct syncppp *ap)
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{
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if (atomic_dec_and_test(&ap->refcnt))
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up(&ap->dead_sem);
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}
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/*
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* Called when a tty is put into sync-PPP line discipline.
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*/
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static int
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ppp_sync_open(struct tty_struct *tty)
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{
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struct syncppp *ap;
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int err;
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ap = kmalloc(sizeof(*ap), GFP_KERNEL);
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err = -ENOMEM;
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if (ap == 0)
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goto out;
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/* initialize the syncppp structure */
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memset(ap, 0, sizeof(*ap));
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ap->tty = tty;
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ap->mru = PPP_MRU;
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spin_lock_init(&ap->xmit_lock);
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spin_lock_init(&ap->recv_lock);
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ap->xaccm[0] = ~0U;
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ap->xaccm[3] = 0x60000000U;
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ap->raccm = ~0U;
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skb_queue_head_init(&ap->rqueue);
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tasklet_init(&ap->tsk, ppp_sync_process, (unsigned long) ap);
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atomic_set(&ap->refcnt, 1);
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init_MUTEX_LOCKED(&ap->dead_sem);
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ap->chan.private = ap;
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ap->chan.ops = &sync_ops;
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ap->chan.mtu = PPP_MRU;
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ap->chan.hdrlen = 2; /* for A/C bytes */
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err = ppp_register_channel(&ap->chan);
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if (err)
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goto out_free;
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tty->disc_data = ap;
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return 0;
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out_free:
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kfree(ap);
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out:
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return err;
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}
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/*
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* Called when the tty is put into another line discipline
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* or it hangs up. We have to wait for any cpu currently
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* executing in any of the other ppp_synctty_* routines to
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* finish before we can call ppp_unregister_channel and free
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* the syncppp struct. This routine must be called from
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* process context, not interrupt or softirq context.
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*/
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static void
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ppp_sync_close(struct tty_struct *tty)
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{
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struct syncppp *ap;
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write_lock_irq(&disc_data_lock);
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ap = tty->disc_data;
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tty->disc_data = NULL;
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write_unlock_irq(&disc_data_lock);
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if (ap == 0)
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return;
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/*
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* We have now ensured that nobody can start using ap from now
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* on, but we have to wait for all existing users to finish.
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* Note that ppp_unregister_channel ensures that no calls to
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* our channel ops (i.e. ppp_sync_send/ioctl) are in progress
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* by the time it returns.
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*/
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if (!atomic_dec_and_test(&ap->refcnt))
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down(&ap->dead_sem);
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tasklet_kill(&ap->tsk);
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ppp_unregister_channel(&ap->chan);
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skb_queue_purge(&ap->rqueue);
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if (ap->tpkt != 0)
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kfree_skb(ap->tpkt);
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kfree(ap);
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}
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/*
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* Called on tty hangup in process context.
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*
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* Wait for I/O to driver to complete and unregister PPP channel.
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* This is already done by the close routine, so just call that.
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*/
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static int ppp_sync_hangup(struct tty_struct *tty)
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{
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ppp_sync_close(tty);
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return 0;
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}
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/*
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* Read does nothing - no data is ever available this way.
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* Pppd reads and writes packets via /dev/ppp instead.
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*/
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static ssize_t
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ppp_sync_read(struct tty_struct *tty, struct file *file,
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unsigned char __user *buf, size_t count)
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{
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return -EAGAIN;
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}
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/*
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* Write on the tty does nothing, the packets all come in
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* from the ppp generic stuff.
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*/
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static ssize_t
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ppp_sync_write(struct tty_struct *tty, struct file *file,
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const unsigned char *buf, size_t count)
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{
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return -EAGAIN;
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}
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static int
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ppp_synctty_ioctl(struct tty_struct *tty, struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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struct syncppp *ap = sp_get(tty);
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int __user *p = (int __user *)arg;
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int err, val;
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if (ap == 0)
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return -ENXIO;
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err = -EFAULT;
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switch (cmd) {
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case PPPIOCGCHAN:
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err = -ENXIO;
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if (ap == 0)
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break;
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err = -EFAULT;
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if (put_user(ppp_channel_index(&ap->chan), p))
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break;
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err = 0;
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break;
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case PPPIOCGUNIT:
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err = -ENXIO;
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if (ap == 0)
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break;
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err = -EFAULT;
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if (put_user(ppp_unit_number(&ap->chan), p))
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break;
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err = 0;
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break;
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case TCGETS:
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case TCGETA:
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err = n_tty_ioctl(tty, file, cmd, arg);
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break;
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case TCFLSH:
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/* flush our buffers and the serial port's buffer */
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if (arg == TCIOFLUSH || arg == TCOFLUSH)
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ppp_sync_flush_output(ap);
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err = n_tty_ioctl(tty, file, cmd, arg);
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break;
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case FIONREAD:
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val = 0;
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if (put_user(val, p))
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break;
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err = 0;
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break;
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default:
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err = -ENOIOCTLCMD;
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}
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sp_put(ap);
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return err;
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}
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/* No kernel lock - fine */
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static unsigned int
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ppp_sync_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
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{
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return 0;
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}
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static int
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ppp_sync_room(struct tty_struct *tty)
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{
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return 65535;
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}
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/*
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* This can now be called from hard interrupt level as well
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* as soft interrupt level or mainline.
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*/
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static void
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ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
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char *cflags, int count)
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{
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struct syncppp *ap = sp_get(tty);
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unsigned long flags;
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if (ap == 0)
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return;
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spin_lock_irqsave(&ap->recv_lock, flags);
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ppp_sync_input(ap, buf, cflags, count);
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spin_unlock_irqrestore(&ap->recv_lock, flags);
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if (skb_queue_len(&ap->rqueue))
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tasklet_schedule(&ap->tsk);
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sp_put(ap);
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if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
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&& tty->driver->unthrottle)
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tty->driver->unthrottle(tty);
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}
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static void
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ppp_sync_wakeup(struct tty_struct *tty)
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{
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struct syncppp *ap = sp_get(tty);
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clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
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if (ap == 0)
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return;
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set_bit(XMIT_WAKEUP, &ap->xmit_flags);
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tasklet_schedule(&ap->tsk);
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sp_put(ap);
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}
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static struct tty_ldisc ppp_sync_ldisc = {
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.owner = THIS_MODULE,
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.magic = TTY_LDISC_MAGIC,
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.name = "pppsync",
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.open = ppp_sync_open,
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.close = ppp_sync_close,
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.hangup = ppp_sync_hangup,
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.read = ppp_sync_read,
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.write = ppp_sync_write,
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.ioctl = ppp_synctty_ioctl,
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.poll = ppp_sync_poll,
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.receive_room = ppp_sync_room,
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.receive_buf = ppp_sync_receive,
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.write_wakeup = ppp_sync_wakeup,
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};
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static int __init
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ppp_sync_init(void)
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{
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int err;
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err = tty_register_ldisc(N_SYNC_PPP, &ppp_sync_ldisc);
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if (err != 0)
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printk(KERN_ERR "PPP_sync: error %d registering line disc.\n",
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err);
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return err;
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}
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/*
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* The following routines provide the PPP channel interface.
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*/
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static int
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ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg)
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{
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struct syncppp *ap = chan->private;
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int err, val;
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u32 accm[8];
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void __user *argp = (void __user *)arg;
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u32 __user *p = argp;
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err = -EFAULT;
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switch (cmd) {
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case PPPIOCGFLAGS:
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val = ap->flags | ap->rbits;
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if (put_user(val, (int __user *) argp))
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break;
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err = 0;
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break;
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case PPPIOCSFLAGS:
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if (get_user(val, (int __user *) argp))
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break;
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ap->flags = val & ~SC_RCV_BITS;
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spin_lock_irq(&ap->recv_lock);
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ap->rbits = val & SC_RCV_BITS;
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spin_unlock_irq(&ap->recv_lock);
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err = 0;
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break;
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case PPPIOCGASYNCMAP:
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if (put_user(ap->xaccm[0], p))
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break;
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err = 0;
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break;
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case PPPIOCSASYNCMAP:
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if (get_user(ap->xaccm[0], p))
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break;
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err = 0;
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break;
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case PPPIOCGRASYNCMAP:
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if (put_user(ap->raccm, p))
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break;
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err = 0;
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break;
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case PPPIOCSRASYNCMAP:
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if (get_user(ap->raccm, p))
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break;
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err = 0;
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break;
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case PPPIOCGXASYNCMAP:
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if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm)))
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break;
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err = 0;
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break;
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case PPPIOCSXASYNCMAP:
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if (copy_from_user(accm, argp, sizeof(accm)))
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break;
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accm[2] &= ~0x40000000U; /* can't escape 0x5e */
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accm[3] |= 0x60000000U; /* must escape 0x7d, 0x7e */
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memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
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err = 0;
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break;
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case PPPIOCGMRU:
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if (put_user(ap->mru, (int __user *) argp))
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break;
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err = 0;
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break;
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case PPPIOCSMRU:
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if (get_user(val, (int __user *) argp))
|
|
break;
|
|
if (val < PPP_MRU)
|
|
val = PPP_MRU;
|
|
ap->mru = val;
|
|
err = 0;
|
|
break;
|
|
|
|
default:
|
|
err = -ENOTTY;
|
|
}
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* This is called at softirq level to deliver received packets
|
|
* to the ppp_generic code, and to tell the ppp_generic code
|
|
* if we can accept more output now.
|
|
*/
|
|
static void ppp_sync_process(unsigned long arg)
|
|
{
|
|
struct syncppp *ap = (struct syncppp *) arg;
|
|
struct sk_buff *skb;
|
|
|
|
/* process received packets */
|
|
while ((skb = skb_dequeue(&ap->rqueue)) != NULL) {
|
|
if (skb->len == 0) {
|
|
/* zero length buffers indicate error */
|
|
ppp_input_error(&ap->chan, 0);
|
|
kfree_skb(skb);
|
|
}
|
|
else
|
|
ppp_input(&ap->chan, skb);
|
|
}
|
|
|
|
/* try to push more stuff out */
|
|
if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_sync_push(ap))
|
|
ppp_output_wakeup(&ap->chan);
|
|
}
|
|
|
|
/*
|
|
* Procedures for encapsulation and framing.
|
|
*/
|
|
|
|
struct sk_buff*
|
|
ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *skb)
|
|
{
|
|
int proto;
|
|
unsigned char *data;
|
|
int islcp;
|
|
|
|
data = skb->data;
|
|
proto = (data[0] << 8) + data[1];
|
|
|
|
/* LCP packets with codes between 1 (configure-request)
|
|
* and 7 (code-reject) must be sent as though no options
|
|
* have been negotiated.
|
|
*/
|
|
islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7;
|
|
|
|
/* compress protocol field if option enabled */
|
|
if (data[0] == 0 && (ap->flags & SC_COMP_PROT) && !islcp)
|
|
skb_pull(skb,1);
|
|
|
|
/* prepend address/control fields if necessary */
|
|
if ((ap->flags & SC_COMP_AC) == 0 || islcp) {
|
|
if (skb_headroom(skb) < 2) {
|
|
struct sk_buff *npkt = dev_alloc_skb(skb->len + 2);
|
|
if (npkt == NULL) {
|
|
kfree_skb(skb);
|
|
return NULL;
|
|
}
|
|
skb_reserve(npkt,2);
|
|
memcpy(skb_put(npkt,skb->len), skb->data, skb->len);
|
|
kfree_skb(skb);
|
|
skb = npkt;
|
|
}
|
|
skb_push(skb,2);
|
|
skb->data[0] = PPP_ALLSTATIONS;
|
|
skb->data[1] = PPP_UI;
|
|
}
|
|
|
|
ap->last_xmit = jiffies;
|
|
|
|
if (skb && ap->flags & SC_LOG_OUTPKT)
|
|
ppp_print_buffer ("send buffer", skb->data, skb->len);
|
|
|
|
return skb;
|
|
}
|
|
|
|
/*
|
|
* Transmit-side routines.
|
|
*/
|
|
|
|
/*
|
|
* Send a packet to the peer over an sync tty line.
|
|
* Returns 1 iff the packet was accepted.
|
|
* If the packet was not accepted, we will call ppp_output_wakeup
|
|
* at some later time.
|
|
*/
|
|
static int
|
|
ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb)
|
|
{
|
|
struct syncppp *ap = chan->private;
|
|
|
|
ppp_sync_push(ap);
|
|
|
|
if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags))
|
|
return 0; /* already full */
|
|
skb = ppp_sync_txmunge(ap, skb);
|
|
if (skb != NULL)
|
|
ap->tpkt = skb;
|
|
else
|
|
clear_bit(XMIT_FULL, &ap->xmit_flags);
|
|
|
|
ppp_sync_push(ap);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Push as much data as possible out to the tty.
|
|
*/
|
|
static int
|
|
ppp_sync_push(struct syncppp *ap)
|
|
{
|
|
int sent, done = 0;
|
|
struct tty_struct *tty = ap->tty;
|
|
int tty_stuffed = 0;
|
|
|
|
if (!spin_trylock_bh(&ap->xmit_lock))
|
|
return 0;
|
|
for (;;) {
|
|
if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags))
|
|
tty_stuffed = 0;
|
|
if (!tty_stuffed && ap->tpkt != 0) {
|
|
set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
|
|
sent = tty->driver->write(tty, ap->tpkt->data, ap->tpkt->len);
|
|
if (sent < 0)
|
|
goto flush; /* error, e.g. loss of CD */
|
|
if (sent < ap->tpkt->len) {
|
|
tty_stuffed = 1;
|
|
} else {
|
|
kfree_skb(ap->tpkt);
|
|
ap->tpkt = NULL;
|
|
clear_bit(XMIT_FULL, &ap->xmit_flags);
|
|
done = 1;
|
|
}
|
|
continue;
|
|
}
|
|
/* haven't made any progress */
|
|
spin_unlock_bh(&ap->xmit_lock);
|
|
if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags)
|
|
|| (!tty_stuffed && ap->tpkt != 0)))
|
|
break;
|
|
if (!spin_trylock_bh(&ap->xmit_lock))
|
|
break;
|
|
}
|
|
return done;
|
|
|
|
flush:
|
|
if (ap->tpkt != 0) {
|
|
kfree_skb(ap->tpkt);
|
|
ap->tpkt = NULL;
|
|
clear_bit(XMIT_FULL, &ap->xmit_flags);
|
|
done = 1;
|
|
}
|
|
spin_unlock_bh(&ap->xmit_lock);
|
|
return done;
|
|
}
|
|
|
|
/*
|
|
* Flush output from our internal buffers.
|
|
* Called for the TCFLSH ioctl.
|
|
*/
|
|
static void
|
|
ppp_sync_flush_output(struct syncppp *ap)
|
|
{
|
|
int done = 0;
|
|
|
|
spin_lock_bh(&ap->xmit_lock);
|
|
if (ap->tpkt != NULL) {
|
|
kfree_skb(ap->tpkt);
|
|
ap->tpkt = NULL;
|
|
clear_bit(XMIT_FULL, &ap->xmit_flags);
|
|
done = 1;
|
|
}
|
|
spin_unlock_bh(&ap->xmit_lock);
|
|
if (done)
|
|
ppp_output_wakeup(&ap->chan);
|
|
}
|
|
|
|
/*
|
|
* Receive-side routines.
|
|
*/
|
|
|
|
/* called when the tty driver has data for us.
|
|
*
|
|
* Data is frame oriented: each call to ppp_sync_input is considered
|
|
* a whole frame. If the 1st flag byte is non-zero then the whole
|
|
* frame is considered to be in error and is tossed.
|
|
*/
|
|
static void
|
|
ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
|
|
char *flags, int count)
|
|
{
|
|
struct sk_buff *skb;
|
|
unsigned char *p;
|
|
|
|
if (count == 0)
|
|
return;
|
|
|
|
if (ap->flags & SC_LOG_INPKT)
|
|
ppp_print_buffer ("receive buffer", buf, count);
|
|
|
|
/* stuff the chars in the skb */
|
|
if ((skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2)) == 0) {
|
|
printk(KERN_ERR "PPPsync: no memory (input pkt)\n");
|
|
goto err;
|
|
}
|
|
/* Try to get the payload 4-byte aligned */
|
|
if (buf[0] != PPP_ALLSTATIONS)
|
|
skb_reserve(skb, 2 + (buf[0] & 1));
|
|
|
|
if (flags != 0 && *flags) {
|
|
/* error flag set, ignore frame */
|
|
goto err;
|
|
} else if (count > skb_tailroom(skb)) {
|
|
/* packet overflowed MRU */
|
|
goto err;
|
|
}
|
|
|
|
p = skb_put(skb, count);
|
|
memcpy(p, buf, count);
|
|
|
|
/* strip address/control field if present */
|
|
p = skb->data;
|
|
if (p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
|
|
/* chop off address/control */
|
|
if (skb->len < 3)
|
|
goto err;
|
|
p = skb_pull(skb, 2);
|
|
}
|
|
|
|
/* decompress protocol field if compressed */
|
|
if (p[0] & 1) {
|
|
/* protocol is compressed */
|
|
skb_push(skb, 1)[0] = 0;
|
|
} else if (skb->len < 2)
|
|
goto err;
|
|
|
|
/* queue the frame to be processed */
|
|
skb_queue_tail(&ap->rqueue, skb);
|
|
return;
|
|
|
|
err:
|
|
/* queue zero length packet as error indication */
|
|
if (skb || (skb = dev_alloc_skb(0))) {
|
|
skb_trim(skb, 0);
|
|
skb_queue_tail(&ap->rqueue, skb);
|
|
}
|
|
}
|
|
|
|
static void __exit
|
|
ppp_sync_cleanup(void)
|
|
{
|
|
if (tty_register_ldisc(N_SYNC_PPP, NULL) != 0)
|
|
printk(KERN_ERR "failed to unregister Sync PPP line discipline\n");
|
|
}
|
|
|
|
module_init(ppp_sync_init);
|
|
module_exit(ppp_sync_cleanup);
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_ALIAS_LDISC(N_SYNC_PPP);
|