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![Eric Dumazet](/assets/img/avatar_default.png)
We got another syzbot report [1] that tells us we must use
write_lock_irq()/write_unlock_irq() to avoid possible deadlock.
[1]
WARNING: inconsistent lock state
5.5.0-rc1-syzkaller #0 Not tainted
--------------------------------
inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-R} usage.
syz-executor826/9605 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffffffff8a128718 (disc_data_lock){+-..}, at: sp_get.isra.0+0x1d/0xf0 drivers/net/ppp/ppp_synctty.c:138
{HARDIRQ-ON-W} state was registered at:
lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485
__raw_write_lock_bh include/linux/rwlock_api_smp.h:203 [inline]
_raw_write_lock_bh+0x33/0x50 kernel/locking/spinlock.c:319
sixpack_close+0x1d/0x250 drivers/net/hamradio/6pack.c:657
tty_ldisc_close.isra.0+0x119/0x1a0 drivers/tty/tty_ldisc.c:489
tty_set_ldisc+0x230/0x6b0 drivers/tty/tty_ldisc.c:585
tiocsetd drivers/tty/tty_io.c:2337 [inline]
tty_ioctl+0xe8d/0x14f0 drivers/tty/tty_io.c:2597
vfs_ioctl fs/ioctl.c:47 [inline]
file_ioctl fs/ioctl.c:545 [inline]
do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
__do_sys_ioctl fs/ioctl.c:756 [inline]
__se_sys_ioctl fs/ioctl.c:754 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
irq event stamp: 3946
hardirqs last enabled at (3945): [<ffffffff87c86e43>] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline]
hardirqs last enabled at (3945): [<ffffffff87c86e43>] _raw_spin_unlock_irq+0x23/0x80 kernel/locking/spinlock.c:199
hardirqs last disabled at (3946): [<ffffffff8100675f>] trace_hardirqs_off_thunk+0x1a/0x1c arch/x86/entry/thunk_64.S:42
softirqs last enabled at (2658): [<ffffffff86a8b4df>] spin_unlock_bh include/linux/spinlock.h:383 [inline]
softirqs last enabled at (2658): [<ffffffff86a8b4df>] clusterip_netdev_event+0x46f/0x670 net/ipv4/netfilter/ipt_CLUSTERIP.c:222
softirqs last disabled at (2656): [<ffffffff86a8b22b>] spin_lock_bh include/linux/spinlock.h:343 [inline]
softirqs last disabled at (2656): [<ffffffff86a8b22b>] clusterip_netdev_event+0x1bb/0x670 net/ipv4/netfilter/ipt_CLUSTERIP.c:196
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(disc_data_lock);
<Interrupt>
lock(disc_data_lock);
*** DEADLOCK ***
5 locks held by syz-executor826/9605:
#0: ffff8880a905e198 (&tty->legacy_mutex){+.+.}, at: tty_lock+0xc7/0x130 drivers/tty/tty_mutex.c:19
#1: ffffffff899a56c0 (rcu_read_lock){....}, at: mutex_spin_on_owner+0x0/0x330 kernel/locking/mutex.c:413
#2: ffff8880a496a2b0 (&(&i->lock)->rlock){-.-.}, at: spin_lock include/linux/spinlock.h:338 [inline]
#2: ffff8880a496a2b0 (&(&i->lock)->rlock){-.-.}, at: serial8250_interrupt+0x2d/0x1a0 drivers/tty/serial/8250/8250_core.c:116
#3: ffffffff8c104048 (&port_lock_key){-.-.}, at: serial8250_handle_irq.part.0+0x24/0x330 drivers/tty/serial/8250/8250_port.c:1823
#4: ffff8880a905e090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref+0x22/0x90 drivers/tty/tty_ldisc.c:288
stack backtrace:
CPU: 1 PID: 9605 Comm: syz-executor826 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x197/0x210 lib/dump_stack.c:118
print_usage_bug.cold+0x327/0x378 kernel/locking/lockdep.c:3101
valid_state kernel/locking/lockdep.c:3112 [inline]
mark_lock_irq kernel/locking/lockdep.c:3309 [inline]
mark_lock+0xbb4/0x1220 kernel/locking/lockdep.c:3666
mark_usage kernel/locking/lockdep.c:3554 [inline]
__lock_acquire+0x1e55/0x4a00 kernel/locking/lockdep.c:3909
lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485
__raw_read_lock include/linux/rwlock_api_smp.h:149 [inline]
_raw_read_lock+0x32/0x50 kernel/locking/spinlock.c:223
sp_get.isra.0+0x1d/0xf0 drivers/net/ppp/ppp_synctty.c:138
sixpack_write_wakeup+0x25/0x340 drivers/net/hamradio/6pack.c:402
tty_wakeup+0xe9/0x120 drivers/tty/tty_io.c:536
tty_port_default_wakeup+0x2b/0x40 drivers/tty/tty_port.c:50
tty_port_tty_wakeup+0x57/0x70 drivers/tty/tty_port.c:387
uart_write_wakeup+0x46/0x70 drivers/tty/serial/serial_core.c:104
serial8250_tx_chars+0x495/0xaf0 drivers/tty/serial/8250/8250_port.c:1761
serial8250_handle_irq.part.0+0x2a2/0x330 drivers/tty/serial/8250/8250_port.c:1834
serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1820 [inline]
serial8250_default_handle_irq+0xc0/0x150 drivers/tty/serial/8250/8250_port.c:1850
serial8250_interrupt+0xf1/0x1a0 drivers/tty/serial/8250/8250_core.c:126
__handle_irq_event_percpu+0x15d/0x970 kernel/irq/handle.c:149
handle_irq_event_percpu+0x74/0x160 kernel/irq/handle.c:189
handle_irq_event+0xa7/0x134 kernel/irq/handle.c:206
handle_edge_irq+0x25e/0x8d0 kernel/irq/chip.c:830
generic_handle_irq_desc include/linux/irqdesc.h:156 [inline]
do_IRQ+0xde/0x280 arch/x86/kernel/irq.c:250
common_interrupt+0xf/0xf arch/x86/entry/entry_64.S:607
</IRQ>
RIP: 0010:cpu_relax arch/x86/include/asm/processor.h:685 [inline]
RIP: 0010:mutex_spin_on_owner+0x247/0x330 kernel/locking/mutex.c:579
Code: c3 be 08 00 00 00 4c 89 e7 e8 e5 06 59 00 4c 89 e0 48 c1 e8 03 42 80 3c 38 00 0f 85 e1 00 00 00 49 8b 04 24 a8 01 75 96 f3 90 <e9> 2f fe ff ff 0f 0b e8 0d 19 09 00 84 c0 0f 85 ff fd ff ff 48 c7
RSP: 0018:ffffc90001eafa20 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffd7
RAX: 0000000000000000 RBX: ffff88809fd9e0c0 RCX: 1ffffffff13266dd
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000000
RBP: ffffc90001eafa60 R08: 1ffff11013d22898 R09: ffffed1013d22899
R10: ffffed1013d22898 R11: ffff88809e9144c7 R12: ffff8880a905e138
R13: ffff88809e9144c0 R14: 0000000000000000 R15: dffffc0000000000
mutex_optimistic_spin kernel/locking/mutex.c:673 [inline]
__mutex_lock_common kernel/locking/mutex.c:962 [inline]
__mutex_lock+0x32b/0x13c0 kernel/locking/mutex.c:1106
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1121
tty_lock+0xc7/0x130 drivers/tty/tty_mutex.c:19
tty_release+0xb5/0xe90 drivers/tty/tty_io.c:1665
__fput+0x2ff/0x890 fs/file_table.c:280
____fput+0x16/0x20 fs/file_table.c:313
task_work_run+0x145/0x1c0 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x8e7/0x2ef0 kernel/exit.c:797
do_group_exit+0x135/0x360 kernel/exit.c:895
__do_sys_exit_group kernel/exit.c:906 [inline]
__se_sys_exit_group kernel/exit.c:904 [inline]
__x64_sys_exit_group+0x44/0x50 kernel/exit.c:904
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43fef8
Code: Bad RIP value.
RSP: 002b:00007ffdb07d2338 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043fef8
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004bf730 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d1180 R14: 0000000000000000 R15: 0000000000000000
Fixes: 6e4e2f811b
("6pack,mkiss: fix lock inconsistency")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
978 lines
23 KiB
C
978 lines
23 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* 6pack.c This module implements the 6pack protocol for kernel-based
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* devices like TTY. It interfaces between a raw TTY and the
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* kernel's AX.25 protocol layers.
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*
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* Authors: Andreas Könsgen <ajk@comnets.uni-bremen.de>
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* Ralf Baechle DL5RB <ralf@linux-mips.org>
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*
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* Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by
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*
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* Laurence Culhane, <loz@holmes.demon.co.uk>
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* Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
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*/
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#include <linux/module.h>
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#include <linux/uaccess.h>
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#include <linux/bitops.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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#include <linux/in.h>
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#include <linux/tty.h>
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#include <linux/errno.h>
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#include <linux/netdevice.h>
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#include <linux/timer.h>
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#include <linux/slab.h>
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#include <net/ax25.h>
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#include <linux/etherdevice.h>
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#include <linux/skbuff.h>
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#include <linux/rtnetlink.h>
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#include <linux/spinlock.h>
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#include <linux/if_arp.h>
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#include <linux/init.h>
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <linux/semaphore.h>
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#include <linux/refcount.h>
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#define SIXPACK_VERSION "Revision: 0.3.0"
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/* sixpack priority commands */
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#define SIXP_SEOF 0x40 /* start and end of a 6pack frame */
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#define SIXP_TX_URUN 0x48 /* transmit overrun */
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#define SIXP_RX_ORUN 0x50 /* receive overrun */
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#define SIXP_RX_BUF_OVL 0x58 /* receive buffer overflow */
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#define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */
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/* masks to get certain bits out of the status bytes sent by the TNC */
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#define SIXP_CMD_MASK 0xC0
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#define SIXP_CHN_MASK 0x07
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#define SIXP_PRIO_CMD_MASK 0x80
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#define SIXP_STD_CMD_MASK 0x40
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#define SIXP_PRIO_DATA_MASK 0x38
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#define SIXP_TX_MASK 0x20
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#define SIXP_RX_MASK 0x10
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#define SIXP_RX_DCD_MASK 0x18
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#define SIXP_LEDS_ON 0x78
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#define SIXP_LEDS_OFF 0x60
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#define SIXP_CON 0x08
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#define SIXP_STA 0x10
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#define SIXP_FOUND_TNC 0xe9
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#define SIXP_CON_ON 0x68
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#define SIXP_DCD_MASK 0x08
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#define SIXP_DAMA_OFF 0
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/* default level 2 parameters */
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#define SIXP_TXDELAY (HZ/4) /* in 1 s */
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#define SIXP_PERSIST 50 /* in 256ths */
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#define SIXP_SLOTTIME (HZ/10) /* in 1 s */
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#define SIXP_INIT_RESYNC_TIMEOUT (3*HZ/2) /* in 1 s */
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#define SIXP_RESYNC_TIMEOUT 5*HZ /* in 1 s */
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/* 6pack configuration. */
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#define SIXP_NRUNIT 31 /* MAX number of 6pack channels */
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#define SIXP_MTU 256 /* Default MTU */
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enum sixpack_flags {
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SIXPF_ERROR, /* Parity, etc. error */
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};
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struct sixpack {
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/* Various fields. */
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struct tty_struct *tty; /* ptr to TTY structure */
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struct net_device *dev; /* easy for intr handling */
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/* These are pointers to the malloc()ed frame buffers. */
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unsigned char *rbuff; /* receiver buffer */
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int rcount; /* received chars counter */
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unsigned char *xbuff; /* transmitter buffer */
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unsigned char *xhead; /* next byte to XMIT */
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int xleft; /* bytes left in XMIT queue */
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unsigned char raw_buf[4];
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unsigned char cooked_buf[400];
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unsigned int rx_count;
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unsigned int rx_count_cooked;
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int mtu; /* Our mtu (to spot changes!) */
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int buffsize; /* Max buffers sizes */
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unsigned long flags; /* Flag values/ mode etc */
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unsigned char mode; /* 6pack mode */
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/* 6pack stuff */
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unsigned char tx_delay;
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unsigned char persistence;
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unsigned char slottime;
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unsigned char duplex;
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unsigned char led_state;
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unsigned char status;
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unsigned char status1;
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unsigned char status2;
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unsigned char tx_enable;
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unsigned char tnc_state;
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struct timer_list tx_t;
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struct timer_list resync_t;
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refcount_t refcnt;
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struct completion dead;
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spinlock_t lock;
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};
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#define AX25_6PACK_HEADER_LEN 0
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static void sixpack_decode(struct sixpack *, const unsigned char[], int);
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static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
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/*
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* Perform the persistence/slottime algorithm for CSMA access. If the
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* persistence check was successful, write the data to the serial driver.
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* Note that in case of DAMA operation, the data is not sent here.
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*/
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static void sp_xmit_on_air(struct timer_list *t)
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{
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struct sixpack *sp = from_timer(sp, t, tx_t);
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int actual, when = sp->slottime;
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static unsigned char random;
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random = random * 17 + 41;
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if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
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sp->led_state = 0x70;
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sp->tty->ops->write(sp->tty, &sp->led_state, 1);
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sp->tx_enable = 1;
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actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
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sp->xleft -= actual;
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sp->xhead += actual;
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sp->led_state = 0x60;
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sp->tty->ops->write(sp->tty, &sp->led_state, 1);
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sp->status2 = 0;
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} else
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mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
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}
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/* ----> 6pack timer interrupt handler and friends. <---- */
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/* Encapsulate one AX.25 frame and stuff into a TTY queue. */
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static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
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{
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unsigned char *msg, *p = icp;
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int actual, count;
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if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
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msg = "oversized transmit packet!";
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goto out_drop;
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}
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if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
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msg = "oversized transmit packet!";
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goto out_drop;
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}
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if (p[0] > 5) {
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msg = "invalid KISS command";
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goto out_drop;
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}
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if ((p[0] != 0) && (len > 2)) {
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msg = "KISS control packet too long";
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goto out_drop;
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}
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if ((p[0] == 0) && (len < 15)) {
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msg = "bad AX.25 packet to transmit";
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goto out_drop;
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}
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count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
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set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
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switch (p[0]) {
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case 1: sp->tx_delay = p[1];
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return;
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case 2: sp->persistence = p[1];
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return;
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case 3: sp->slottime = p[1];
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return;
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case 4: /* ignored */
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return;
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case 5: sp->duplex = p[1];
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return;
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}
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if (p[0] != 0)
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return;
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/*
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* In case of fullduplex or DAMA operation, we don't take care about the
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* state of the DCD or of any timers, as the determination of the
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* correct time to send is the job of the AX.25 layer. We send
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* immediately after data has arrived.
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*/
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if (sp->duplex == 1) {
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sp->led_state = 0x70;
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sp->tty->ops->write(sp->tty, &sp->led_state, 1);
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sp->tx_enable = 1;
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actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
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sp->xleft = count - actual;
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sp->xhead = sp->xbuff + actual;
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sp->led_state = 0x60;
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sp->tty->ops->write(sp->tty, &sp->led_state, 1);
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} else {
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sp->xleft = count;
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sp->xhead = sp->xbuff;
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sp->status2 = count;
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sp_xmit_on_air(&sp->tx_t);
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}
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return;
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out_drop:
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sp->dev->stats.tx_dropped++;
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netif_start_queue(sp->dev);
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if (net_ratelimit())
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printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
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}
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/* Encapsulate an IP datagram and kick it into a TTY queue. */
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static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct sixpack *sp = netdev_priv(dev);
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if (skb->protocol == htons(ETH_P_IP))
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return ax25_ip_xmit(skb);
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spin_lock_bh(&sp->lock);
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/* We were not busy, so we are now... :-) */
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netif_stop_queue(dev);
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dev->stats.tx_bytes += skb->len;
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sp_encaps(sp, skb->data, skb->len);
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spin_unlock_bh(&sp->lock);
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dev_kfree_skb(skb);
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return NETDEV_TX_OK;
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}
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static int sp_open_dev(struct net_device *dev)
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{
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struct sixpack *sp = netdev_priv(dev);
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if (sp->tty == NULL)
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return -ENODEV;
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return 0;
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}
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/* Close the low-level part of the 6pack channel. */
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static int sp_close(struct net_device *dev)
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{
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struct sixpack *sp = netdev_priv(dev);
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spin_lock_bh(&sp->lock);
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if (sp->tty) {
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/* TTY discipline is running. */
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clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
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}
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netif_stop_queue(dev);
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spin_unlock_bh(&sp->lock);
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return 0;
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}
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static int sp_set_mac_address(struct net_device *dev, void *addr)
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{
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struct sockaddr_ax25 *sa = addr;
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netif_tx_lock_bh(dev);
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netif_addr_lock(dev);
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memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
|
|
netif_addr_unlock(dev);
|
|
netif_tx_unlock_bh(dev);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct net_device_ops sp_netdev_ops = {
|
|
.ndo_open = sp_open_dev,
|
|
.ndo_stop = sp_close,
|
|
.ndo_start_xmit = sp_xmit,
|
|
.ndo_set_mac_address = sp_set_mac_address,
|
|
};
|
|
|
|
static void sp_setup(struct net_device *dev)
|
|
{
|
|
/* Finish setting up the DEVICE info. */
|
|
dev->netdev_ops = &sp_netdev_ops;
|
|
dev->needs_free_netdev = true;
|
|
dev->mtu = SIXP_MTU;
|
|
dev->hard_header_len = AX25_MAX_HEADER_LEN;
|
|
dev->header_ops = &ax25_header_ops;
|
|
|
|
dev->addr_len = AX25_ADDR_LEN;
|
|
dev->type = ARPHRD_AX25;
|
|
dev->tx_queue_len = 10;
|
|
|
|
/* Only activated in AX.25 mode */
|
|
memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
|
|
memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
|
|
|
|
dev->flags = 0;
|
|
}
|
|
|
|
/* Send one completely decapsulated IP datagram to the IP layer. */
|
|
|
|
/*
|
|
* This is the routine that sends the received data to the kernel AX.25.
|
|
* 'cmd' is the KISS command. For AX.25 data, it is zero.
|
|
*/
|
|
|
|
static void sp_bump(struct sixpack *sp, char cmd)
|
|
{
|
|
struct sk_buff *skb;
|
|
int count;
|
|
unsigned char *ptr;
|
|
|
|
count = sp->rcount + 1;
|
|
|
|
sp->dev->stats.rx_bytes += count;
|
|
|
|
if ((skb = dev_alloc_skb(count + 1)) == NULL)
|
|
goto out_mem;
|
|
|
|
ptr = skb_put(skb, count + 1);
|
|
*ptr++ = cmd; /* KISS command */
|
|
|
|
memcpy(ptr, sp->cooked_buf + 1, count);
|
|
skb->protocol = ax25_type_trans(skb, sp->dev);
|
|
netif_rx(skb);
|
|
sp->dev->stats.rx_packets++;
|
|
|
|
return;
|
|
|
|
out_mem:
|
|
sp->dev->stats.rx_dropped++;
|
|
}
|
|
|
|
|
|
/* ----------------------------------------------------------------------- */
|
|
|
|
/*
|
|
* We have a potential race on dereferencing tty->disc_data, because the tty
|
|
* layer provides no locking at all - thus one cpu could be running
|
|
* sixpack_receive_buf while another calls sixpack_close, which zeroes
|
|
* tty->disc_data and frees the memory that sixpack_receive_buf is using. The
|
|
* best way to fix this is to use a rwlock in the tty struct, but for now we
|
|
* use a single global rwlock for all ttys in ppp line discipline.
|
|
*/
|
|
static DEFINE_RWLOCK(disc_data_lock);
|
|
|
|
static struct sixpack *sp_get(struct tty_struct *tty)
|
|
{
|
|
struct sixpack *sp;
|
|
|
|
read_lock(&disc_data_lock);
|
|
sp = tty->disc_data;
|
|
if (sp)
|
|
refcount_inc(&sp->refcnt);
|
|
read_unlock(&disc_data_lock);
|
|
|
|
return sp;
|
|
}
|
|
|
|
static void sp_put(struct sixpack *sp)
|
|
{
|
|
if (refcount_dec_and_test(&sp->refcnt))
|
|
complete(&sp->dead);
|
|
}
|
|
|
|
/*
|
|
* Called by the TTY driver when there's room for more data. If we have
|
|
* more packets to send, we send them here.
|
|
*/
|
|
static void sixpack_write_wakeup(struct tty_struct *tty)
|
|
{
|
|
struct sixpack *sp = sp_get(tty);
|
|
int actual;
|
|
|
|
if (!sp)
|
|
return;
|
|
if (sp->xleft <= 0) {
|
|
/* Now serial buffer is almost free & we can start
|
|
* transmission of another packet */
|
|
sp->dev->stats.tx_packets++;
|
|
clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
|
|
sp->tx_enable = 0;
|
|
netif_wake_queue(sp->dev);
|
|
goto out;
|
|
}
|
|
|
|
if (sp->tx_enable) {
|
|
actual = tty->ops->write(tty, sp->xhead, sp->xleft);
|
|
sp->xleft -= actual;
|
|
sp->xhead += actual;
|
|
}
|
|
|
|
out:
|
|
sp_put(sp);
|
|
}
|
|
|
|
/* ----------------------------------------------------------------------- */
|
|
|
|
/*
|
|
* Handle the 'receiver data ready' interrupt.
|
|
* This function is called by the tty module in the kernel when
|
|
* a block of 6pack data has been received, which can now be decapsulated
|
|
* and sent on to some IP layer for further processing.
|
|
*/
|
|
static void sixpack_receive_buf(struct tty_struct *tty,
|
|
const unsigned char *cp, char *fp, int count)
|
|
{
|
|
struct sixpack *sp;
|
|
int count1;
|
|
|
|
if (!count)
|
|
return;
|
|
|
|
sp = sp_get(tty);
|
|
if (!sp)
|
|
return;
|
|
|
|
/* Read the characters out of the buffer */
|
|
count1 = count;
|
|
while (count) {
|
|
count--;
|
|
if (fp && *fp++) {
|
|
if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
|
|
sp->dev->stats.rx_errors++;
|
|
continue;
|
|
}
|
|
}
|
|
sixpack_decode(sp, cp, count1);
|
|
|
|
sp_put(sp);
|
|
tty_unthrottle(tty);
|
|
}
|
|
|
|
/*
|
|
* Try to resync the TNC. Called by the resync timer defined in
|
|
* decode_prio_command
|
|
*/
|
|
|
|
#define TNC_UNINITIALIZED 0
|
|
#define TNC_UNSYNC_STARTUP 1
|
|
#define TNC_UNSYNCED 2
|
|
#define TNC_IN_SYNC 3
|
|
|
|
static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
|
|
{
|
|
char *msg;
|
|
|
|
switch (new_tnc_state) {
|
|
default: /* gcc oh piece-o-crap ... */
|
|
case TNC_UNSYNC_STARTUP:
|
|
msg = "Synchronizing with TNC";
|
|
break;
|
|
case TNC_UNSYNCED:
|
|
msg = "Lost synchronization with TNC\n";
|
|
break;
|
|
case TNC_IN_SYNC:
|
|
msg = "Found TNC";
|
|
break;
|
|
}
|
|
|
|
sp->tnc_state = new_tnc_state;
|
|
printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
|
|
}
|
|
|
|
static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
|
|
{
|
|
int old_tnc_state = sp->tnc_state;
|
|
|
|
if (old_tnc_state != new_tnc_state)
|
|
__tnc_set_sync_state(sp, new_tnc_state);
|
|
}
|
|
|
|
static void resync_tnc(struct timer_list *t)
|
|
{
|
|
struct sixpack *sp = from_timer(sp, t, resync_t);
|
|
static char resync_cmd = 0xe8;
|
|
|
|
/* clear any data that might have been received */
|
|
|
|
sp->rx_count = 0;
|
|
sp->rx_count_cooked = 0;
|
|
|
|
/* reset state machine */
|
|
|
|
sp->status = 1;
|
|
sp->status1 = 1;
|
|
sp->status2 = 0;
|
|
|
|
/* resync the TNC */
|
|
|
|
sp->led_state = 0x60;
|
|
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
|
|
sp->tty->ops->write(sp->tty, &resync_cmd, 1);
|
|
|
|
|
|
/* Start resync timer again -- the TNC might be still absent */
|
|
mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
|
|
}
|
|
|
|
static inline int tnc_init(struct sixpack *sp)
|
|
{
|
|
unsigned char inbyte = 0xe8;
|
|
|
|
tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
|
|
|
|
sp->tty->ops->write(sp->tty, &inbyte, 1);
|
|
|
|
mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Open the high-level part of the 6pack channel.
|
|
* This function is called by the TTY module when the
|
|
* 6pack line discipline is called for. Because we are
|
|
* sure the tty line exists, we only have to link it to
|
|
* a free 6pcack channel...
|
|
*/
|
|
static int sixpack_open(struct tty_struct *tty)
|
|
{
|
|
char *rbuff = NULL, *xbuff = NULL;
|
|
struct net_device *dev;
|
|
struct sixpack *sp;
|
|
unsigned long len;
|
|
int err = 0;
|
|
|
|
if (!capable(CAP_NET_ADMIN))
|
|
return -EPERM;
|
|
if (tty->ops->write == NULL)
|
|
return -EOPNOTSUPP;
|
|
|
|
dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
|
|
sp_setup);
|
|
if (!dev) {
|
|
err = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
sp = netdev_priv(dev);
|
|
sp->dev = dev;
|
|
|
|
spin_lock_init(&sp->lock);
|
|
refcount_set(&sp->refcnt, 1);
|
|
init_completion(&sp->dead);
|
|
|
|
/* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
|
|
|
|
len = dev->mtu * 2;
|
|
|
|
rbuff = kmalloc(len + 4, GFP_KERNEL);
|
|
xbuff = kmalloc(len + 4, GFP_KERNEL);
|
|
|
|
if (rbuff == NULL || xbuff == NULL) {
|
|
err = -ENOBUFS;
|
|
goto out_free;
|
|
}
|
|
|
|
spin_lock_bh(&sp->lock);
|
|
|
|
sp->tty = tty;
|
|
|
|
sp->rbuff = rbuff;
|
|
sp->xbuff = xbuff;
|
|
|
|
sp->mtu = AX25_MTU + 73;
|
|
sp->buffsize = len;
|
|
sp->rcount = 0;
|
|
sp->rx_count = 0;
|
|
sp->rx_count_cooked = 0;
|
|
sp->xleft = 0;
|
|
|
|
sp->flags = 0; /* Clear ESCAPE & ERROR flags */
|
|
|
|
sp->duplex = 0;
|
|
sp->tx_delay = SIXP_TXDELAY;
|
|
sp->persistence = SIXP_PERSIST;
|
|
sp->slottime = SIXP_SLOTTIME;
|
|
sp->led_state = 0x60;
|
|
sp->status = 1;
|
|
sp->status1 = 1;
|
|
sp->status2 = 0;
|
|
sp->tx_enable = 0;
|
|
|
|
netif_start_queue(dev);
|
|
|
|
timer_setup(&sp->tx_t, sp_xmit_on_air, 0);
|
|
|
|
timer_setup(&sp->resync_t, resync_tnc, 0);
|
|
|
|
spin_unlock_bh(&sp->lock);
|
|
|
|
/* Done. We have linked the TTY line to a channel. */
|
|
tty->disc_data = sp;
|
|
tty->receive_room = 65536;
|
|
|
|
/* Now we're ready to register. */
|
|
err = register_netdev(dev);
|
|
if (err)
|
|
goto out_free;
|
|
|
|
tnc_init(sp);
|
|
|
|
return 0;
|
|
|
|
out_free:
|
|
kfree(xbuff);
|
|
kfree(rbuff);
|
|
|
|
free_netdev(dev);
|
|
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
|
|
/*
|
|
* Close down a 6pack channel.
|
|
* This means flushing out any pending queues, and then restoring the
|
|
* TTY line discipline to what it was before it got hooked to 6pack
|
|
* (which usually is TTY again).
|
|
*/
|
|
static void sixpack_close(struct tty_struct *tty)
|
|
{
|
|
struct sixpack *sp;
|
|
|
|
write_lock_irq(&disc_data_lock);
|
|
sp = tty->disc_data;
|
|
tty->disc_data = NULL;
|
|
write_unlock_irq(&disc_data_lock);
|
|
if (!sp)
|
|
return;
|
|
|
|
/*
|
|
* We have now ensured that nobody can start using ap from now on, but
|
|
* we have to wait for all existing users to finish.
|
|
*/
|
|
if (!refcount_dec_and_test(&sp->refcnt))
|
|
wait_for_completion(&sp->dead);
|
|
|
|
/* We must stop the queue to avoid potentially scribbling
|
|
* on the free buffers. The sp->dead completion is not sufficient
|
|
* to protect us from sp->xbuff access.
|
|
*/
|
|
netif_stop_queue(sp->dev);
|
|
|
|
del_timer_sync(&sp->tx_t);
|
|
del_timer_sync(&sp->resync_t);
|
|
|
|
/* Free all 6pack frame buffers. */
|
|
kfree(sp->rbuff);
|
|
kfree(sp->xbuff);
|
|
|
|
unregister_netdev(sp->dev);
|
|
}
|
|
|
|
/* Perform I/O control on an active 6pack channel. */
|
|
static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
|
|
unsigned int cmd, unsigned long arg)
|
|
{
|
|
struct sixpack *sp = sp_get(tty);
|
|
struct net_device *dev;
|
|
unsigned int tmp, err;
|
|
|
|
if (!sp)
|
|
return -ENXIO;
|
|
dev = sp->dev;
|
|
|
|
switch(cmd) {
|
|
case SIOCGIFNAME:
|
|
err = copy_to_user((void __user *) arg, dev->name,
|
|
strlen(dev->name) + 1) ? -EFAULT : 0;
|
|
break;
|
|
|
|
case SIOCGIFENCAP:
|
|
err = put_user(0, (int __user *) arg);
|
|
break;
|
|
|
|
case SIOCSIFENCAP:
|
|
if (get_user(tmp, (int __user *) arg)) {
|
|
err = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
sp->mode = tmp;
|
|
dev->addr_len = AX25_ADDR_LEN;
|
|
dev->hard_header_len = AX25_KISS_HEADER_LEN +
|
|
AX25_MAX_HEADER_LEN + 3;
|
|
dev->type = ARPHRD_AX25;
|
|
|
|
err = 0;
|
|
break;
|
|
|
|
case SIOCSIFHWADDR: {
|
|
char addr[AX25_ADDR_LEN];
|
|
|
|
if (copy_from_user(&addr,
|
|
(void __user *) arg, AX25_ADDR_LEN)) {
|
|
err = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
netif_tx_lock_bh(dev);
|
|
memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
|
|
netif_tx_unlock_bh(dev);
|
|
|
|
err = 0;
|
|
break;
|
|
}
|
|
|
|
default:
|
|
err = tty_mode_ioctl(tty, file, cmd, arg);
|
|
}
|
|
|
|
sp_put(sp);
|
|
|
|
return err;
|
|
}
|
|
|
|
static struct tty_ldisc_ops sp_ldisc = {
|
|
.owner = THIS_MODULE,
|
|
.magic = TTY_LDISC_MAGIC,
|
|
.name = "6pack",
|
|
.open = sixpack_open,
|
|
.close = sixpack_close,
|
|
.ioctl = sixpack_ioctl,
|
|
.receive_buf = sixpack_receive_buf,
|
|
.write_wakeup = sixpack_write_wakeup,
|
|
};
|
|
|
|
/* Initialize 6pack control device -- register 6pack line discipline */
|
|
|
|
static const char msg_banner[] __initconst = KERN_INFO \
|
|
"AX.25: 6pack driver, " SIXPACK_VERSION "\n";
|
|
static const char msg_regfail[] __initconst = KERN_ERR \
|
|
"6pack: can't register line discipline (err = %d)\n";
|
|
|
|
static int __init sixpack_init_driver(void)
|
|
{
|
|
int status;
|
|
|
|
printk(msg_banner);
|
|
|
|
/* Register the provided line protocol discipline */
|
|
if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
|
|
printk(msg_regfail, status);
|
|
|
|
return status;
|
|
}
|
|
|
|
static const char msg_unregfail[] = KERN_ERR \
|
|
"6pack: can't unregister line discipline (err = %d)\n";
|
|
|
|
static void __exit sixpack_exit_driver(void)
|
|
{
|
|
int ret;
|
|
|
|
if ((ret = tty_unregister_ldisc(N_6PACK)))
|
|
printk(msg_unregfail, ret);
|
|
}
|
|
|
|
/* encode an AX.25 packet into 6pack */
|
|
|
|
static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
|
|
int length, unsigned char tx_delay)
|
|
{
|
|
int count = 0;
|
|
unsigned char checksum = 0, buf[400];
|
|
int raw_count = 0;
|
|
|
|
tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
|
|
tx_buf_raw[raw_count++] = SIXP_SEOF;
|
|
|
|
buf[0] = tx_delay;
|
|
for (count = 1; count < length; count++)
|
|
buf[count] = tx_buf[count];
|
|
|
|
for (count = 0; count < length; count++)
|
|
checksum += buf[count];
|
|
buf[length] = (unsigned char) 0xff - checksum;
|
|
|
|
for (count = 0; count <= length; count++) {
|
|
if ((count % 3) == 0) {
|
|
tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
|
|
tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
|
|
} else if ((count % 3) == 1) {
|
|
tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
|
|
tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
|
|
} else {
|
|
tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
|
|
tx_buf_raw[raw_count++] = (buf[count] >> 2);
|
|
}
|
|
}
|
|
if ((length % 3) != 2)
|
|
raw_count++;
|
|
tx_buf_raw[raw_count++] = SIXP_SEOF;
|
|
return raw_count;
|
|
}
|
|
|
|
/* decode 4 sixpack-encoded bytes into 3 data bytes */
|
|
|
|
static void decode_data(struct sixpack *sp, unsigned char inbyte)
|
|
{
|
|
unsigned char *buf;
|
|
|
|
if (sp->rx_count != 3) {
|
|
sp->raw_buf[sp->rx_count++] = inbyte;
|
|
|
|
return;
|
|
}
|
|
|
|
buf = sp->raw_buf;
|
|
sp->cooked_buf[sp->rx_count_cooked++] =
|
|
buf[0] | ((buf[1] << 2) & 0xc0);
|
|
sp->cooked_buf[sp->rx_count_cooked++] =
|
|
(buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
|
|
sp->cooked_buf[sp->rx_count_cooked++] =
|
|
(buf[2] & 0x03) | (inbyte << 2);
|
|
sp->rx_count = 0;
|
|
}
|
|
|
|
/* identify and execute a 6pack priority command byte */
|
|
|
|
static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
|
|
{
|
|
int actual;
|
|
|
|
if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
|
|
|
|
/* RX and DCD flags can only be set in the same prio command,
|
|
if the DCD flag has been set without the RX flag in the previous
|
|
prio command. If DCD has not been set before, something in the
|
|
transmission has gone wrong. In this case, RX and DCD are
|
|
cleared in order to prevent the decode_data routine from
|
|
reading further data that might be corrupt. */
|
|
|
|
if (((sp->status & SIXP_DCD_MASK) == 0) &&
|
|
((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
|
|
if (sp->status != 1)
|
|
printk(KERN_DEBUG "6pack: protocol violation\n");
|
|
else
|
|
sp->status = 0;
|
|
cmd &= ~SIXP_RX_DCD_MASK;
|
|
}
|
|
sp->status = cmd & SIXP_PRIO_DATA_MASK;
|
|
} else { /* output watchdog char if idle */
|
|
if ((sp->status2 != 0) && (sp->duplex == 1)) {
|
|
sp->led_state = 0x70;
|
|
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
|
|
sp->tx_enable = 1;
|
|
actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
|
|
sp->xleft -= actual;
|
|
sp->xhead += actual;
|
|
sp->led_state = 0x60;
|
|
sp->status2 = 0;
|
|
|
|
}
|
|
}
|
|
|
|
/* needed to trigger the TNC watchdog */
|
|
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
|
|
|
|
/* if the state byte has been received, the TNC is present,
|
|
so the resync timer can be reset. */
|
|
|
|
if (sp->tnc_state == TNC_IN_SYNC)
|
|
mod_timer(&sp->resync_t, jiffies + SIXP_INIT_RESYNC_TIMEOUT);
|
|
|
|
sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
|
|
}
|
|
|
|
/* identify and execute a standard 6pack command byte */
|
|
|
|
static void decode_std_command(struct sixpack *sp, unsigned char cmd)
|
|
{
|
|
unsigned char checksum = 0, rest = 0;
|
|
short i;
|
|
|
|
switch (cmd & SIXP_CMD_MASK) { /* normal command */
|
|
case SIXP_SEOF:
|
|
if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
|
|
if ((sp->status & SIXP_RX_DCD_MASK) ==
|
|
SIXP_RX_DCD_MASK) {
|
|
sp->led_state = 0x68;
|
|
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
|
|
}
|
|
} else {
|
|
sp->led_state = 0x60;
|
|
/* fill trailing bytes with zeroes */
|
|
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
|
|
rest = sp->rx_count;
|
|
if (rest != 0)
|
|
for (i = rest; i <= 3; i++)
|
|
decode_data(sp, 0);
|
|
if (rest == 2)
|
|
sp->rx_count_cooked -= 2;
|
|
else if (rest == 3)
|
|
sp->rx_count_cooked -= 1;
|
|
for (i = 0; i < sp->rx_count_cooked; i++)
|
|
checksum += sp->cooked_buf[i];
|
|
if (checksum != SIXP_CHKSUM) {
|
|
printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
|
|
} else {
|
|
sp->rcount = sp->rx_count_cooked-2;
|
|
sp_bump(sp, 0);
|
|
}
|
|
sp->rx_count_cooked = 0;
|
|
}
|
|
break;
|
|
case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
|
|
break;
|
|
case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
|
|
break;
|
|
case SIXP_RX_BUF_OVL:
|
|
printk(KERN_DEBUG "6pack: RX buffer overflow\n");
|
|
}
|
|
}
|
|
|
|
/* decode a 6pack packet */
|
|
|
|
static void
|
|
sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
|
|
{
|
|
unsigned char inbyte;
|
|
int count1;
|
|
|
|
for (count1 = 0; count1 < count; count1++) {
|
|
inbyte = pre_rbuff[count1];
|
|
if (inbyte == SIXP_FOUND_TNC) {
|
|
tnc_set_sync_state(sp, TNC_IN_SYNC);
|
|
del_timer(&sp->resync_t);
|
|
}
|
|
if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
|
|
decode_prio_command(sp, inbyte);
|
|
else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
|
|
decode_std_command(sp, inbyte);
|
|
else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
|
|
decode_data(sp, inbyte);
|
|
}
|
|
}
|
|
|
|
MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
|
|
MODULE_DESCRIPTION("6pack driver for AX.25");
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_ALIAS_LDISC(N_6PACK);
|
|
|
|
module_init(sixpack_init_driver);
|
|
module_exit(sixpack_exit_driver);
|