Traditionally, changes to struct file->f_flags have been done under BKL
protection, or with no protection at all. This patch causes all f_flags
changes after file open/creation time to be done under protection of
f_lock. This allows the removal of some BKL usage and fixes a number of
longstanding (if microscopic) races.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
__tty_open could return (to userspace) holding the tty_mutex thanks to a
regression introduced by 4a2b5fddd5 ("Move
tty lookup/reopen to caller").
This was found by bisecting an fsfuzzer problem. Admittedly I have no
idea how it managed to tickle this 100% reliably, but it is clearly a
regression and when hit leaves the box in a completely unusable state.
This patch lets the fsfuzzer test complete every time.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have special case logic for resizing pty/tty pairs. We also have a per
driver resize method so for the pty case we should use it.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixed sparse warning:
drivers/char/tty_io.c:1216:19: warning: symbol 'tty_driver_lookup_tty' was not declared. Should it be static?
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes the loss of echoed (and other ldisc-generated characters) when
the tty is stopped or when the driver output buffer is full (happens
frequently for input during continuous program output, such as ^C)
and removes the Big Kernel Lock from the N_TTY line discipline.
Adds an "echo buffer" to the N_TTY line discipline that handles all
ldisc-generated output (including echoed characters). Along with the
loss of characters, this also fixes the associated loss of sync between
tty output and the ldisc state when characters cannot be immediately
written to the tty driver.
The echo buffer stores (in addition to characters) state operations that need
to be done at the time of character output (like management of the column
position). This allows echo to cooperate correctly with program output,
since the ldisc state remains consistent with actual characters written.
Since the echo buffer code now isolates the tty column state code
to the process_out* and process_echoes functions, we can remove the
Big Kernel Lock (BKL) and replace it with mutex locks.
Highlights are:
* Handles echo (and other ldisc output) when tty driver buffer is full
- continuous program output can block echo
* Saves echo when tty is in stopped state (e.g. ^S)
- (e.g.: ^Q will correctly cause held characters to be released for output)
* Control character pairs (e.g. "^C") are treated atomically and not
split up by interleaved program output
* Line discipline state is kept consistent with characters sent to
the tty driver
* Remove the big kernel lock (BKL) from N_TTY line discipline
Signed-off-by: Joe Peterson <joe@skyrush.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
AUDIT_TTY records currently log all data read by processes marked for
TTY input auditing, even if the data was "pushed back" using the TIOCSTI
ioctl, not typed by the user.
This patch records all TIOCSTI calls to disambiguate the input. It
generates one audit message per character pushed back; considering
TIOCSTI is used very rarely, this simple solution is probably good
enough. (The only program I could find that uses TIOCSTI is mailx/nail
in "header editing" mode, e.g. using the ~h escape. mailx is used very
rarely, and the escapes are used even rarer.)
Signed-Off-By: Miloslav Trmac <mitr@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Morris <jmorris@namei.org>
When no console is configured tty_open tries to call kref_get on a NULL
pointer, return ENODEV instead.
Signed-off-by: Will Newton <will.newton@gmail.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
proc_clear_tty() gets called with interrupts off (while holding the task list
lock) from sys_setid. This means that it needs the _irqsave version of the
locking primitives.
Reported-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Tested-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/char/tty_io.c:1413:17: warning: symbol 'buf' shadows an earlier one
drivers/char/tty_io.c:1379:20: originally declared here
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Copy the simplification from the pty unix98 special case to the generic one.
This allows us to kill off driver->termios_locked entirely which is nice. We
have to whack bits of the cris driver as it meddles in places it shouldn't
providing its own arrays that were never used anyway.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pass-in 'inode' or 'tty' parameter to devpts interfaces. With multiple
devpts instances, these parameters will be used in subsequent patches
to identify the instance of devpts mounted. The parameters also help
simplify devpts implementation.
Changelog[v3]:
- minor changes due to merge with ttydev updates
- rename parameters to emphasize they are ptmx or pts inodes
- pass-in tty_struct * to devpts_pty_kill() (this will help
cleanup the get_node() call in a subsequent patch)
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move tty_driver_lookup_tty() and tty_reopen() from tty_init_dev()
into tty_open() (one of the two callers of tty_init_dev()). These
calls are not really required in ptmx_open(), the other caller,
since ptmx_open() would be setting up a new tty.
Changelog[v2]:
- remove the lookup and reopen calls from ptmx_open
- merge with recent changes to ttydev tree
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The majority of the remaining init_dev code is pty special cases. We
refactor this code into the driver->install method.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Original suggestion and proposal from Sukadev Bhattiprolu.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have the lookup operation abstracted which is nice for pty cleanup but
we really want to abstract the add/remove entries as well so that we can
pull the pty code out of the tty core and create a clear defined interface
for the tty driver table.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix up the naming, style and extract some bits of code into the driver
specific code
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the 'find-tty' and 'fast-track-open' parts of init_dev() to
separate functions.
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Carry on pushing code out of tty_io when it belongs to other drivers. I'm
not 100% happy with some of this and it will be worth revisiting some of the
exports later when the restructuring work is done.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Right now there are various drivers that try to use tty->count to know when
they get the final close. Aristeau Rozanski showed while debugging the vt
sysfs race that this isn't entirely safe.
Instead of driver side tricks to work around this introduce a shutdown which
is called when the tty is being destructed. This also means that the shutdown
method is tied into the refcounting.
Use this to rework the console close/sysfs logic.
Remove lots of special case code from the tty core code. The pty code can now
have a shutdown() method that replaces the special case hackery in the tree
free up paths.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The open path for ptmx slaves is via the ptmx device. Opening them any
other way is not allowed. Vegard Nossum found that previously this was not
the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently it is sometimes locked by the tty mutex and sometimes by the
sighand lock. The latter is in fact correct and now we can hand back referenced
objects we can fix this up without problems around sleeping functions.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We now have the infrastructure to sort this out but rather than teaching
the syscall tty lock rules we move the hard work into a tty helper
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is pure tty code so put it in the tty layer where it can be with the
locking relevant material it uses
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We now return a kref covered tty reference. That ensures the tty structure
doesn't go away when you have a return from get_current_tty. This is not
enough to protect you from most of the resources being freed behind your
back - yet.
[Updated to include fixes for SELinux problems found by Andrew Morton and
an s390 leak found while debugging the former]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We always use the real tty one for stuff so the pty one should not be
compared. As we propagate window changes to both it doesn't currently
matter but will when we tidy up the pty termios logic a bit more
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This moves us towards sanity and should mean our termios locking is now
complete and comprehensive.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The tty layer keeps driver module counts that are used so the driver knows
when it can be unloaded. For obvious reasons we want to tie that to the
refcounting properly.
At this point the driver side itself isn't refcounted nicely but we can do
that later and kref the drivers.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce a kref to the tty structure and use it to protect the tty->signal
tty references. For now we don't introduce it for anything else.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The two are basically independent chunks of code so lets split them up for
readability and sanity. It also makes the API boundaries much clearer.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Right now we have ifdefs and hooks in the core ioctl handler for TIOCLINUX
and then test if its a console. This is brain dead. Instead call the
tioclinux helper from the relevant driver ioctl methods.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The tty_find_polling_driver() routine did not correctly check the base
part of the tty name. This can lead to kgdboc selecting an incorrect
driver, as well as accepting a completely invalid tty such as "echo
ffff0 > /sys/module/kgdboc/parameters/kgdboc".
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Kanru Chen posted a patch versus the old code which deals with the case
where you resize the pty side of a pty/tty pair. In that situation the
termios data is updated for both pty and tty but the locks are not held
for the right side.
This implements the fix differently against the updated tty code. Patch
by self but the hard bit (noticing and fixing the bug) is thanks to Kanru
Chen.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This moves it to being a tty operation. That removes special cases and now
also means that resize can be picked up by um and other non vt consoles
which may have a resize operation.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While testing our KVM code for s390 (starting and killall kvm in a loop)
I can reproduce the following oops:
Unable to handle kernel pointer dereference at virtual kernel address 6b6b6b6b6b6b6000 Oops: 0038 [#1] SMP
Modules linked in: dm_multipath sunrpc qeth_l3 qeth_l2 dm_mod qeth
ccwgroup CPU: 1 Not tainted 2.6.27-rc1 #54
Process kuli (pid: 4409, task: 00000000b6aa5940, ksp: 00000000b7343e10)
Krnl PSW : 0704e00180000000 00000000002e0b8c
(disassociate_ctty+0x1c0/0x288) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3
CC:2 PM:0 EA:3 Krnl GPRS: 0000000000000000 6b6b6b6b6b6b6b6b
0000000000000001 00000000000003a6 00000000002e0a46 00000000004b4160
0000000000000001 00000000bbd79758 00000000b7343e58 00000000b8854148
00000000bd34dea0 00000000b7343c20 0000000000000001 00000000004b6d08
00000000002e0a46 00000000b7343c20 Krnl Code: 00000000002e0b7e:
eb9fb0a00004 lmg %r9,%r15,160(%r11) 00000000002e0b84:
07f4 bcr 15,%r4 00000000002e0b86:
e31090080004 lg %r1,8(%r9) >00000000002e0b8c:
d501109cd000 clc 156(2,%r1),0(%r13) 00000000002e0b92:
a784ff5d brc 8,2e0a4c 00000000002e0b96:
b9040029 lgr %r2,%r9 00000000002e0b9a:
c0e5fffff9c3 brasl %r14,2dff20 00000000002e0ba0:
a7f4ff56 brc 15,2e0a4c Call Trace:
([<00000000002e0a46>] disassociate_ctty+0x7a/0x288)
[<0000000000141fe6>] do_exit+0x212/0x8d4
[<0000000000142708>] do_group_exit+0x60/0xcc
[<0000000000150660>] get_signal_to_deliver+0x270/0x3ac
[<000000000010bfd6>] do_signal+0x8e/0x8dc
[<0000000000113772>] sysc_sigpending+0xe/0x22
[<000001ff0000b134>] 0x1ff0000b134
INFO: lockdep is turned off.
Last Breaking-Event-Address:
[<00000000002e0a48>] disassociate_ctty+0x7c/0x288
Kernel panic - not syncing: Fatal exception: panic_on_oops
It seems that tty was already free in disassocate_ctty when it tries
to dereference tty->driver.
After moving the lock_kernel before the mutex_unlock, I can no longer
reproduce the problem.
[ This is a temporary partial fix for the documented and long standing
race in disassociate_tty. This stops most problem cases for now.
For the next release the -next tree has an initial implementation of
kref counting for tty structures and this quickfix will be dropped.
- Alan ]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by; Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the removal of the Solaris binary emulation the export of
proc_clear_tty became unused.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch removes the no longer used is_tty().
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some hardware needs to do break handling itself and may have partial
support only. Make break_ctl return an error code. Add a tty driver flag
so you can indicate driver hardware side break support.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
device_create() is race-prone, so use the race-free
device_create_drvdata() instead as device_create() is going away.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Reverse the order of one test and it gets much more readable
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Every tty driver has its own concept of a port structure and because
they all differ we cannot extract commonality. Begin fixing this by
creating a structure drivers can elect to use so that over time we can
push fields into this and create commonality and then introduce common
methods.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the line disciplines towards a conventional ->ops arrangement. For
the moment the actual 'tty_ldisc' struct in the tty is kept as part of
the tty struct but this can then be changed if it turns out that when it
all settles down we want to refcount ldiscs separately to the tty.
Pull the ldisc code out of /proc and put it with our ldisc code.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Not sure how this came to get inverted but it appears to have been my
mess up.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jonathan Corbet