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path: root/drivers/tty/tty_io.c
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* drivers/tty: require read access for controlling terminalJann Horn2015-10-041-4/+27
| | | | | | | | | This is mostly a hardening fix, given that write-only access to other users' ttys is usually only given through setgid tty executables. Signed-off-by: Jann Horn <jann@thejh.net> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: don't leak cdev in tty_cdev_add()Leon Yu2015-10-041-2/+7
| | | | | | | | | | | | | | | | Commit a3a10ce3429e ("Avoid usb reset crashes by making tty_io cdevs truly dynamic") which mixes using cdev_alloc() and cdev_init() is problematic. Subsequent call to cdev_init() after cdev_alloc() sets kobj release method from cdev_dynamic_release() to cdev_default_release() and thus makes it impossible to free allocated cdev. This patch also consolidates error path of cdev_add() as cdev can also leak here if things went wrong. Signed-off-by: Leon Yu <chianglungyu@gmail.com> Fixes: a3a10ce3429e ("Avoid usb reset crashes by making tty_io cdevs truly dynamic") Acked-by: Richard Watts <rrw@kynesim.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Avoid usb reset crashes by making tty_io cdevs truly dynamicRichard Watts2015-08-041-8/+16
| | | | | | | | Avoid usb reset crashes by making tty_io cdevs truly dynamic Signed-off-by: Richard Watts <rrw@kynesim.co.uk> Reported-by: Duncan Mackintosh <DMackintosh@cbnl.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Replace #ifdef TTY_DEBUG_HANGUP with tty_debug_hangup()Peter Hurley2015-07-241-29/+18Star
| | | | | | | | Add tty_debug_hangup() macro which uses tty_debug to print the debug message; remove inlined #ifdefs. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: core: Add tty_debug() for printk(KERN_DEBUG) messagesPeter Hurley2015-07-241-24/+17Star
| | | | | | | | | | | Introduce tty_debug() macro to output uniform debug information for tty core debug messages (function name and tty name). Note: printk(KERN_DEBUG) is retained here over pr_debug() since messages can be enabled in non-DEBUG builds. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: core: Improve debug message contentPeter Hurley2015-07-241-13/+16
| | | | | | | | | Output the function name, tty name, and invariant failure (if applicable). Add the tty count to the tty_open() message. Fix the disassociate_ctty() message, which printed the NULL pointer and the wrong message. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: add missing rcu_read_lock for task_pgrpPatrick Donnelly2015-07-241-5/+12
| | | | | | | | | | task_pgrp requires an rcu or tasklist lock to be obtained if the returned pid is to be dereferenced, which kill_pgrp does. Obtain an RCU lock for the duration of use. Signed-off-by: Patrick Donnelly <batrick@batbytes.com> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: remove buf parameter from tty_name()Rasmus Villemoes2015-05-061-17/+11Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | tty_name no longer uses the buf parameter, so remove it along with all the 64 byte stack buffers that used to be passed in. Mostly generated by the coccinelle script @depends on patch@ identifier buf; constant C; expression tty; @@ - char buf[C]; <+... - tty_name(tty, buf) + tty_name(tty) ...+> allmodconfig compiles, so I'm fairly confident the stack buffers weren't used for other purposes as well. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Jesper Nilsson <jesper.nilsson@axis.com> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: return tty->name directly from tty_nameRasmus Villemoes2015-05-061-5/+3Star
| | | | | | | | | | | All users of tty_name pass the return value (the provided buffer) to some printf-like function. We can thus avoid the strcpy and, more importantly, later remove the buf parameter completely, eliminating the need for some 64 byte stack buffers. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: constify return type of tty_nameRasmus Villemoes2015-05-061-1/+1
| | | | | | | | | | | | | | All users of tty_name pass the result directly to a printf-like function. This means we can actually let tty_name return the literal "NULL tty" or tty->name directly, avoiding the strcpy and a lot of medium-sized stack buffers. In preparation for that, make the return type const char*. While at it, we can also constify the tty parameter. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: clean up the tty time logic a bitGreg Kroah-Hartman2015-03-261-2/+8
| | | | | | | | | | We only care if anything other than the lower 3 bits of the tty has changed, so just check that way, which makes it a bit faster, and more obvious what is going on. Also, document this for future developers to understand why we did this. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
* tty: Use static attribute groups for sysfs entriesTakashi Iwai2015-03-261-4/+10
| | | | | | | | | Instead of manual calls of device_create_file() and device_remove_file(), pass the static attribute groups using device_create_with_groups(). Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: fix up atime/mtime mess, take fourJiri Slaby2015-03-071-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This problem was taken care of three times already in * b0de59b5733d18b0d1974a060860a8b5c1b36a2e (TTY: do not update atime/mtime on read/write), * 37b7f3c76595e23257f61bd80b223de8658617ee (TTY: fix atime/mtime regression), and * b0b885657b6c8ef63a46bc9299b2a7715d19acde (tty: fix up atime/mtime mess, take three) But it still misses one point. As John Paul correctly points out, we do not care about setting date. If somebody ever changes wall time backwards (by mistake for example), tty timestamps are never updated until the original wall time passes. So check the absolute difference of times and if it large than "8 seconds or so", always update the time. That means we will update immediatelly when changing time. Ergo, CAP_SYS_TIME can foul the check, but it was always that way. Thanks John for serving me this so nicely debugged. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Reported-by: John Paul Perry <john_paul.perry@alcatel-lucent.com> Cc: <stable@vger.kernel.org> # all, as b0b885657 was backported Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Prevent hw state corruption in exclusive mode reopenPeter Hurley2015-01-091-4/+3Star
| | | | | | | | | | | | | Exclusive mode ttys (TTY_EXCLUSIVE) do not allow further reopens; fail the condition before associating the file pointer and calling the driver open() method. Prevents DTR programming when the tty is already in exclusive mode. Reported-by: Shreyas Bethur <shreyas.bethur@ni.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Shreyas Bethur <shreyas.bethur@ni.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Deletion of unnecessary checks before two function callsMarkus Elfring2014-11-271-4/+2Star
| | | | | | | | | | | The functions put_device() and tty_kref_put() test whether their argument is NULL and then return immediately. Thus the test around the call is not needed. This issue was detected by using the Coccinelle software. Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: warn on deprecated serial flagsJiri Slaby2014-11-071-0/+21
| | | | | | | | | | | | | | | | | When somebody calls TIOCSSERIAL ioctl with serial flags to set one of * ASYNC_SESSION_LOCKOUT * ASYNC_PGRP_LOCKOUT * ASYNC_CALLOUT_NOHUP * ASYNC_AUTOPROBE nothing happens. We actually ignore the flags for over a decade at least (I checked 2.6.0). So start yelling at users who use those flags, that they shouldn't. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Call methods in modern stylePeter Hurley2014-11-061-6/+6
| | | | | | | | The use of older function ptr calling style, (*fn)(), makes static analysis more error-prone; replace with modern fn() style. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Replace open-coded test with tty_hung_up_p()Peter Hurley2014-11-061-1/+1
| | | | | | | tty_hung_up_p() is equivalent to the open-coded test in tty_open(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge branch 'tty-linus' into 'tty-testing'Greg Kroah-Hartman2014-11-061-3/+12
|\ | | | | | | | | | | | | We need the fixes in drivers/tty/tty_io.c that were done in there for future patches in this branch. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * tty: Prevent "read/write wait queue active!" log floodingPeter Hurley2014-11-061-2/+6
| | | | | | | | | | | | | | | | | | Only print one warning when a task is on the read_wait or write_wait wait queue at final tty release. Cc: <stable@vger.kernel.org> # 3.4.x+ Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * tty: Fix high cpu load if tty is unreleaseablePeter Hurley2014-11-061-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Kernel oops can cause the tty to be unreleaseable (for example, if n_tty_read() crashes while on the read_wait queue). This will cause tty_release() to endlessly loop without sleeping. Use a killable sleep timeout which grows by 2n+1 jiffies over the interval [0, 120 secs.) and then jumps to forever (but still killable). NB: killable just allows for the task to be rewoken manually, not to be terminated. Cc: <stable@vger.kernel.org> # since before 2.6.32 Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Flush ldisc buffer atomically with tty flip buffersPeter Hurley2014-11-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | tty_ldisc_flush() first clears the line discipline input buffer, then clears the tty flip buffers. However, this allows for existing data in the tty flip buffers to be added after the ldisc input buffer has been cleared, but before the flip buffers have been cleared. Add an optional ldisc parameter to tty_buffer_flush() to allow tty_ldisc_flush() to pass the ldisc to clear. NB: Initially, the plan was to do this automatically in tty_buffer_flush(). However, an audit of the behavior of existing line disciplines showed that performing a ldisc buffer flush on ioctl(TCFLSH) was not always the outcome. For example, some line disciplines have flush_buffer() methods but not ioctl() methods, so a ->flush_buffer() command would be unexpected. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Change tty lock order to master->slavePeter Hurley2014-11-061-4/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When releasing the master pty, the slave pty also needs to be locked to prevent concurrent tty count changes for the slave pty and to ensure that only one parallel master and slave release observe the final close, and proceed to destruct the pty pair. Conversely, when releasing the slave pty, locking the master pty is not necessary (since the master's state can be inferred by the slave tty count). Introduce tty_lock_slave()/tty_unlock_slave() which acquires/releases the tty lock of the slave pty. Remove tty_lock_pair()/tty_unlock_pair(). Dropping the tty_lock is no longer required to re-establish a stable lock order. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Simplify tty_release() state checksPeter Hurley2014-11-061-10/+9Star
| | | | | | | | | | | | | | | | | | | | | | | | The local o_tty variable in tty_release() is now accessed only when closing the pty master. Set o_tty to slave pty when closing pty master, otherwise NULL; use o_tty != NULL as replacement for pty_master. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Simplify tty_release_checks() interfacePeter Hurley2014-11-061-3/+4
| | | | | | | | | | | | | | | | | | Passing the 'other' tty to tty_release_checks() only makes sense for a pty pair; make o_tty scope local instead. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Simplify tty_ldisc_release() interfacePeter Hurley2014-11-061-1/+1
| | | | | | | | | | | | | | | | | | Passing the 'other' tty to tty_ldisc_release() only makes sense for a pty pair; make o_tty function local instead. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Fold pty pair handling into tty_flush_works()Peter Hurley2014-11-061-5/+7
| | | | | | | | | | | | | | | | | | Perform work flush for both ends of a pty pair within tty_flush_works(), rather than calling twice. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Simplify pty pair teardown logicPeter Hurley2014-11-061-19/+10Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When the slave side closes and its tty count is 0, the pty pair can be destroyed; the master side must have already closed for the slave side tty count to be 0. Thus, only the pty master close must check if the slave side has closed by checking the slave tty count. Remove the pre-computed closing flags and check the actual count(s). Regular ttys are unaffected by this change. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Document check_tty_count() requires tty_lock heldPeter Hurley2014-11-061-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Holding the tty_lock() is necessary to prevent concurrent changes to the tty count that may cause it to differ from the open file list count. The tty_lock() is already held at all call sites. NB: Note that the check for the pty master tty count is safe because the slave's tty_lock() is held while decrementing the pty master tty count. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Don't release tty locks for wait queue sanity checkPeter Hurley2014-11-061-6/+2Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Releasing the tty locks while waiting for the tty wait queues to be empty is no longer necessary nor desirable. Prior to "tty: Don't take tty_mutex for tty count changes", dropping the tty locks was necessary to reestablish the correct lock order between tty_mutex and the tty locks. Dropping the global tty_mutex was necessary; otherwise new ttys could not have been opened while waiting. However, without needing the global tty_mutex held, the tty locks for the releasing tty can now be held through the sleep. The sanity check is for abnormal conditions caused by kernel bugs, not for recoverable errors caused by misbehaving userspace; dropping the tty locks only allows the tty state to get more sideways. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Don't take tty_mutex for tty count changesPeter Hurley2014-11-061-6/+0Star
| | | | | | | | | | | | | | | | | | | | Holding tty_mutex is no longer required to serialize changes to the tty_count or to prevent concurrent opens of closing ttys; tty_lock() is sufficient. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Remove TTY_CLOSINGPeter Hurley2014-11-061-12/+2Star
| | | | | | | | | | | | | | | | | | | | Now that re-open is not permitted for a legacy BSD pty master, using TTY_CLOSING to indicate when a tty can be torn-down is no longer necessary. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Drop tty_mutex before tty reopenPeter Hurley2014-11-061-8/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Holding tty_mutex for a tty re-open is no longer necessary since "tty: Clarify re-open behavior of master ptys". Because the slave tty count is no longer accessed by tty_reopen(), holding tty_mutex to prevent concurrent final tty_release() of the slave pty is not required. As with "tty: Re-open /dev/tty without tty_mutex", holding a tty kref until the tty_lock is acquired is sufficient to ensure the tty has not been freed, which, in turn, is sufficient to ensure the tty_lock can be safely acquired and the tty count can be safely retrieved. A non-zero tty count with the tty lock held guarantees that release_tty() has not run and cannot run concurrently with tty_reopen(). Change tty_driver_lookup_tty() to acquire the tty kref, which allows the tty_mutex to be dropped before acquiring the tty lock. Dropping the tty_mutex before attempting the tty_lock allows other ttys to be opened and released, without needing this tty_reopen() to complete. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Re-open /dev/tty without tty_mutexPeter Hurley2014-11-061-26/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Opening /dev/tty (ie., the controlling tty for the current task) is always a re-open of the underlying tty. Because holding the tty_lock is sufficient for safely re-opening a tty, and because having a tty kref is sufficient for safely acquiring the tty_lock [1], tty_open_current_tty() does not require holding tty_mutex. Repurpose tty_open_current_tty() to perform the re-open itself and refactor tty_open(). [1] Analysis of safely re-opening the current tty w/o tty_mutex get_current_tty() gets a tty kref from the already kref'ed tty value of current->signal->tty while holding the sighand lock for the current task. This guarantees that the tty pointer returned from get_current_tty() points to a tty which remains referenceable while holding the kref. Although release_tty() may run concurrently, and thus the driver reference may be removed, release_one_tty() cannot have run, and won't while holding the tty kref. This, in turn, guarantees the tty_lock() can safely be acquired (since tty->magic and tty->legacy_mutex are still a valid dereferences). The tty_lock() also gets a tty kref to prevent the tty_unlock() from dereferencing a released tty. Thus, the kref returned from get_current_tty() can be released. Lastly, the first operation of tty_reopen() is to check the tty count. If non-zero, this ensures release_tty() is not running concurrently, and the driver references have not been removed. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Check tty->count instead of TTY_CLOSING in tty_reopen()Peter Hurley2014-11-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Although perhaps not obvious, the TTY_CLOSING bit is set when the tty count has been decremented to 0 (which occurs while holding tty_lock). The only other case when tty count is 0 during a re-open is when a legacy BSD pty master has been opened in parallel but after the pty slave, which is unsupported and returns an error. Thus !tty->count contains the complete set of degenerate conditions under which a tty open fails. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Clarify re-open behavior of master ptysPeter Hurley2014-11-061-11/+4Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Re-opening master ptys is not allowed. Once opened and for the remaining lifetime of the master pty, its tty count is 1. If its tty count has dropped to 0, then the master pty was closed and TTY_CLOSING was set, and destruction may begin imminently. Besides the normal case of a legacy BSD pty master being re-opened (which always returns -EIO), this code is only reachable in 2 degenerate cases: 1. The pty master is the controlling terminal (this is possible through the TIOCSCTTY ioctl). pty masters are not designed to be controlling terminals and it's an oversight that tiocsctty() ever let that happen. The attempted open of /dev/tty will always fail. No known program does this. 2. The legacy BSD pty slave was opened first. The slave open will fail in pty_open() and tty_release() will commence. But before tty_release() claims the tty_mutex, there is a very small window where a parallel master open might succeed. In a test of racing legacy BSD slave and master parallel opens, where: slave open attempts: 10000 success:4527 failure:5473 master open attempts: 11728 success:5789 failure:5939 only 8 master open attempts would have succeeded reaching this code and successfully opened the master pty. This case is not possible with SysV ptys. Always return -EIO if a master pty is re-opened or the slave is opened first and the master opened in parallel (for legacy BSD ptys). Furthermore, now that changing the slave's count is not required, the tty_lock is sufficient for preventing concurrent changes to the tty being re-opened (or failing re-opening). Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Remove TTY_HUPPINGPeter Hurley2014-11-061-11/+1Star
| | | | | | | | | | | | | | | | | | | | | | | | Now that tty_ldisc_hangup() does not drop the tty lock, it is no longer possible to observe TTY_HUPPING while holding the tty lock on another cpu. Remove TTY_HUPPING bit definition. Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Update code comment in __proc_set_tty()Peter Hurley2014-11-061-1/+4
| | | | | | | | | | | | | | | | | | | | The session and foreground process group pid references will be non-NULL if tiocsctty() is stealing the controlling tty from another session (ie., arg == 1 in tiocsctty()). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Serialize proc_set_tty() with tty_lockPeter Hurley2014-11-061-8/+5Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Setting the controlling terminal for a session occurs with either the first open of a non-pty master tty or with ioctl(TIOCSCTTY). Since only the session leader can set the controlling terminal for a session (and the session leader cannot change), it is not necessary to prevent a process from attempting to set different ttys as the controlling terminal concurrently. So it's only necessary to prevent the same tty from becoming the controlling terminal for different session leaders. The tty_lock() is sufficient to prevent concurrent proc_set_tty() for the same tty. Remove the tty_mutex lock region; add tty_lock() to tiocsctty(). While this may appear to allow a race condition between opening the controlling tty via tty_open_current_tty() and stealing the controlling tty via ioctl(TIOCSCTTY, 1), that race condition already existed. Even if the tty_mutex prevented stealing the controlling tty while tty_open_current_tty() returned the original controlling tty, it cannot prevent stealing the controlling tty before tty_open() returns. Thus, tty_open() could already return a no-longer-controlling tty when opening /dev/tty. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Move session_of_pgrp() and make staticPeter Hurley2014-11-061-0/+21
| | | | | | | | | | | | | | | | | | tiocspgrp() is the lone caller of session_of_pgrp(); relocate and limit to file scope. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Fix multiple races when setting the controlling terminalPeter Hurley2014-11-061-6/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Claim a read lock on the tasklist_lock while setting the controlling terminal for the session leader. This fixes multiple races: 1. task_pgrp() and task_session() cannot be safely dereferenced, such as passing to get_pid(), without holding either rcu_read_lock() or tasklist_lock 2. setsid() unwisely allows any thread in the thread group to make the thread group leader the session leader; this makes the unlocked reads of ->signal->leader and signal->tty potentially unordered, stale or even have spurious values. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Remove !tty condition from __proc_set_tty()Peter Hurley2014-11-061-13/+12Star
| | | | | | | | | | | | | | | | | | The tty parameter to __proc_set_tty() cannot be NULL; all call sites have already dereferenced tty. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Replace open-coded tty_get_pgrp()Peter Hurley2014-11-061-6/+2Star
| | | | | | | | | | | | | | | | Replace open-coded instances of tty_get_pgrp(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Remove tsk parameter from proc_set_tty()Peter Hurley2014-11-061-14/+14
| | | | | | | | | | | | | | | | | | Only the current task itself can set its controlling tty (other than before the task has been forked). Equivalent to existing usage. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Reorder proc_set_tty() and related fnsPeter Hurley2014-11-061-63/+62Star
| | | | | | | | | | | | | | | | | | Move the controlling tty-related functions and remove forward declarations for __proc_set_tty() and proc_set_tty(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Remove tty_pair_get_tty()/tty_pair_get_pty() apiPeter Hurley2014-11-061-11/+5Star
| | | | | | | | | | | | | | | | | | | | tty_pair_get_pty() has no in-tree users and tty_pair_get_tty() has only one file-local user. Remove the external declarations, the export declarations, and declare tty_pair_get_tty() static. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Remove sparse lock annotations from tty_write_lock()/_unlock()Peter Hurley2014-11-061-2/+0Star
|/ | | | | | | | | | | | | | | | | | | sparse lock annotations cannot represent conditional acquire, such as mutex_lock_interruptible() or mutex_trylock(), and produce sparse warnings at _every_ correct call site. Remove lock annotations from tty_write_lock() and tty_write_unlock(). Fixes sparse warnings: drivers/tty/tty_io.c:1083:13: warning: context imbalance in 'tty_write_unlock' - wrong count at exit drivers/tty/tty_io.c:1090:12: warning: context imbalance in 'tty_write_lock' - wrong count at exit drivers/tty/tty_io.c:1211:17: warning: context imbalance in 'tty_write_message' - unexpected unlock drivers/tty/tty_io.c:1233:16: warning: context imbalance in 'tty_write' - different lock contexts for basic block drivers/tty/tty_io.c:1285:5: warning: context imbalance in 'tty_send_xchar' - different lock contexts for basic block drivers/tty/tty_io.c:2653:12: warning: context imbalance in 'send_break' - different lock contexts for basic block Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge tag 'locks-v3.18-1' of git://git.samba.org/jlayton/linuxLinus Torvalds2014-10-111-1/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull file locking related changes from Jeff Layton: "This release is a little more busy for file locking changes than the last: - a set of patches from Kinglong Mee to fix the lockowner handling in knfsd - a pile of cleanups to the internal file lease API. This should get us a bit closer to allowing for setlease methods that can block. There are some dependencies between mine and Bruce's trees this cycle, and I based my tree on top of the requisite patches in Bruce's tree" * tag 'locks-v3.18-1' of git://git.samba.org/jlayton/linux: (26 commits) locks: fix fcntl_setlease/getlease return when !CONFIG_FILE_LOCKING locks: flock_make_lock should return a struct file_lock (or PTR_ERR) locks: set fl_owner for leases to filp instead of current->files locks: give lm_break a return value locks: __break_lease cleanup in preparation of allowing direct removal of leases locks: remove i_have_this_lease check from __break_lease locks: move freeing of leases outside of i_lock locks: move i_lock acquisition into generic_*_lease handlers locks: define a lm_setup handler for leases locks: plumb a "priv" pointer into the setlease routines nfsd: don't keep a pointer to the lease in nfs4_file locks: clean up vfs_setlease kerneldoc comments locks: generic_delete_lease doesn't need a file_lock at all nfsd: fix potential lease memory leak in nfs4_setlease locks: close potential race in lease_get_mtime security: make security_file_set_fowner, f_setown and __f_setown void return locks: consolidate "nolease" routines locks: remove lock_may_read and lock_may_write lockd: rip out deferred lock handling from testlock codepath NFSD: Get reference of lockowner when coping file_lock ...
| * security: make security_file_set_fowner, f_setown and __f_setown void returnJeff Layton2014-09-091-1/+2
| | | | | | | | | | | | | | | | | | | | security_file_set_fowner always returns 0, so make it f_setown and __f_setown void return functions and fix up the error handling in the callers. Cc: linux-security-module@vger.kernel.org Signed-off-by: Jeff Layton <jlayton@primarydata.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* | tty: Move and rename send_prio_char() as tty_send_xchar()Peter Hurley2014-09-241-2/+31
| | | | | | | | | | | | | | | | | | Relocate the file-scope function, send_prio_char(), as a global helper tty_send_xchar(). Remove the global declarations for tty_write_lock()/tty_write_unlock(), as these are file-scope only now. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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