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path: root/drivers/tty/pty.c
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2021-04-15tty: create internal tty.h fileGreg Kroah-Hartman1-0/+1
There are a number of functions and #defines in include/linux/tty.h that do not belong there as they are private to the tty core code. Create an initial drivers/tty/tty.h file and copy the odd "tty logging" macros into it to seed the file with some initial things that we know nothing outside of the tty core should be calling. Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Jiri Slaby <jirislaby@kernel.org> Link: https://lore.kernel.org/r/20210408125134.3016837-2-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-04-02tty: pty: Add a blank line after declarationsXiaofei Tan1-0/+4
Add a blank line after declarations, reported by checkpatch.pl. Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com> Link: https://lore.kernel.org/r/1617351990-5189-1-git-send-email-tanxiaofei@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-10Revert "drivers:tty:pty: Fix a race causing data loss on close"Greg Kroah-Hartman1-13/+2
This reverts commit 33d4ae98859873ddd49e22e4ca724387548b3d89. Pierre-Louis writes: Our SOF/audio CI shows an across-the-board regression when we try v5.12-rc1, specifically on pause/resume tests with an interactive terminal running 'aplay -i' commands managed by expect to simulate the user pressing the space bar to pause/unpause. It turns out the processes are not longer killed and the audio devices remain busy (see publicly available test results listed below). git bisect points to commit 33d4ae9885987 ("drivers:tty:pty: Fix a race causing data loss on close"). Reverting the patch fixes the issue on all test devices. Further analysis with Corey Minyard points to a problem where a slave tty will not get a SIGHUP when the master is closed. So revert this for now: Reported-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Link: https://lore.kernel.org/r/00154592-c5ee-aaba-956e-b265473b53bc@linux.intel.com Cc: Corey Minyard <cminyard@mvista.com> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Mark Brown <broonie@kernel.org>, Fixes: 33d4ae988598 ("drivers:tty:pty: Fix a race causing data loss on close") Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-07drivers:tty:pty: Fix a race causing data loss on closeCorey Minyard1-2/+13
Remove the tty_vhangup() from the pty code and just release the redirect. The tty_vhangup() results in data loss and data out of order issues. If you write to a pty master an immediately close the pty master, the receiver might get a chunk of data dropped, but then receive some later data. That's obviously something rather unexpected for a user. It certainly confused my test program. It turns out that tty_vhangup() on the slave pty gets called from pty_close(), and that causes the data on the slave side to be flushed, but due to races more data can be copied into the slave side's buffer after that. Consider the following sequence: thread1 thread2 thread3 ------- ------- ------- | |-write data into buffer, | | n_tty buffer is filled | | along with other buffers | |-pty_close(master) | |--tty_vhangup(slave) | |---tty_ldisc_hangup() | |----n_tty_flush_buffer() | |-----reset_buffer_flags() |-n_tty_read() | |--up_read(&tty->termios_rwsem); | |------down_read(&tty->termios_rwsem) | |------clear n_tty buffer contents | |------up_read(&tty->termios_rwsem) |--tty_buffer_flush_work() | |--schedules work calling | | flush_to_ldisc() | | |-flush_to_ldisc() | |--receive_buf() | |---tty_port_default_receive_buf() | |----tty_ldisc_receive_buf() | |-----n_tty_receive_buf2() | |------n_tty_receive_buf_common() | |-------down_read(&tty->termios_rwsem) | |-------__receive_buf() | | copies data into n_tty buffer | |-------up_read(&tty->termios_rwsem) |--down_read(&tty->termios_rwsem) |--copy buffer data to user >From this sequence, you can see that thread2 writes to the buffer then only clears the part of the buffer in n_tty. The n_tty receive buffer code then copies more data into the n_tty buffer. But part of the vhangup, releasing the redirect, is still required to avoid issues with consoles running on pty slaves. So do that. As far as I can tell, that is all that should be required. Signed-off-by: Corey Minyard <cminyard@mvista.com> Link: https://lore.kernel.org/r/20201124004902.1398477-3-minyard@acm.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-07tty: pty, remove BUG_ON from pty_closeJiri Slaby1-1/+0
tty->ops->close is always called with a valid tty, so the BUG_ON cannot trigger. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20210105120239.28031-5-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-06tty: pty: Provide descriptions for the 'file' parametersLee Jones1-0/+2
Fixes the following W=1 kernel build warning(s): drivers/tty/pty.c:710: warning: Function parameter or member 'file' not described in 'ptm_unix98_lookup' drivers/tty/pty.c:726: warning: Function parameter or member 'file' not described in 'pts_unix98_lookup' Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: "C. Scott Ananian" <cananian@alumni.princeton.edu> Signed-off-by: Lee Jones <lee.jones@linaro.org> Link: https://lore.kernel.org/r/20201104193549.4026187-17-lee.jones@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-04pty: do tty_flip_buffer_push without port->lock in pty_writeArtem Savkov1-1/+1
b6da31b2c07c "tty: Fix data race in tty_insert_flip_string_fixed_flag" puts tty_flip_buffer_push under port->lock introducing the following possible circular locking dependency: [30129.876566] ====================================================== [30129.876566] WARNING: possible circular locking dependency detected [30129.876567] 5.9.0-rc2+ #3 Tainted: G S W [30129.876568] ------------------------------------------------------ [30129.876568] sysrq.sh/1222 is trying to acquire lock: [30129.876569] ffffffff92c39480 (console_owner){....}-{0:0}, at: console_unlock+0x3fe/0xa90 [30129.876572] but task is already holding lock: [30129.876572] ffff888107cb9018 (&pool->lock/1){-.-.}-{2:2}, at: show_workqueue_state.cold.55+0x15b/0x6ca [30129.876576] which lock already depends on the new lock. [30129.876577] the existing dependency chain (in reverse order) is: [30129.876578] -> #3 (&pool->lock/1){-.-.}-{2:2}: [30129.876581] _raw_spin_lock+0x30/0x70 [30129.876581] __queue_work+0x1a3/0x10f0 [30129.876582] queue_work_on+0x78/0x80 [30129.876582] pty_write+0x165/0x1e0 [30129.876583] n_tty_write+0x47f/0xf00 [30129.876583] tty_write+0x3d6/0x8d0 [30129.876584] vfs_write+0x1a8/0x650 [30129.876588] -> #2 (&port->lock#2){-.-.}-{2:2}: [30129.876590] _raw_spin_lock_irqsave+0x3b/0x80 [30129.876591] tty_port_tty_get+0x1d/0xb0 [30129.876592] tty_port_default_wakeup+0xb/0x30 [30129.876592] serial8250_tx_chars+0x3d6/0x970 [30129.876593] serial8250_handle_irq.part.12+0x216/0x380 [30129.876593] serial8250_default_handle_irq+0x82/0xe0 [30129.876594] serial8250_interrupt+0xdd/0x1b0 [30129.876595] __handle_irq_event_percpu+0xfc/0x850 [30129.876602] -> #1 (&port->lock){-.-.}-{2:2}: [30129.876605] _raw_spin_lock_irqsave+0x3b/0x80 [30129.876605] serial8250_console_write+0x12d/0x900 [30129.876606] console_unlock+0x679/0xa90 [30129.876606] register_console+0x371/0x6e0 [30129.876607] univ8250_console_init+0x24/0x27 [30129.876607] console_init+0x2f9/0x45e [30129.876609] -> #0 (console_owner){....}-{0:0}: [30129.876611] __lock_acquire+0x2f70/0x4e90 [30129.876612] lock_acquire+0x1ac/0xad0 [30129.876612] console_unlock+0x460/0xa90 [30129.876613] vprintk_emit+0x130/0x420 [30129.876613] printk+0x9f/0xc5 [30129.876614] show_pwq+0x154/0x618 [30129.876615] show_workqueue_state.cold.55+0x193/0x6ca [30129.876615] __handle_sysrq+0x244/0x460 [30129.876616] write_sysrq_trigger+0x48/0x4a [30129.876616] proc_reg_write+0x1a6/0x240 [30129.876617] vfs_write+0x1a8/0x650 [30129.876619] other info that might help us debug this: [30129.876620] Chain exists of: [30129.876621] console_owner --> &port->lock#2 --> &pool->lock/1 [30129.876625] Possible unsafe locking scenario: [30129.876626] CPU0 CPU1 [30129.876626] ---- ---- [30129.876627] lock(&pool->lock/1); [30129.876628] lock(&port->lock#2); [30129.876630] lock(&pool->lock/1); [30129.876631] lock(console_owner); [30129.876633] *** DEADLOCK *** [30129.876634] 5 locks held by sysrq.sh/1222: [30129.876634] #0: ffff8881d3ce0470 (sb_writers#3){.+.+}-{0:0}, at: vfs_write+0x359/0x650 [30129.876637] #1: ffffffff92c612c0 (rcu_read_lock){....}-{1:2}, at: __handle_sysrq+0x4d/0x460 [30129.876640] #2: ffffffff92c612c0 (rcu_read_lock){....}-{1:2}, at: show_workqueue_state+0x5/0xf0 [30129.876642] #3: ffff888107cb9018 (&pool->lock/1){-.-.}-{2:2}, at: show_workqueue_state.cold.55+0x15b/0x6ca [30129.876645] #4: ffffffff92c39980 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0x123/0x420 [30129.876648] stack backtrace: [30129.876649] CPU: 3 PID: 1222 Comm: sysrq.sh Tainted: G S W 5.9.0-rc2+ #3 [30129.876649] Hardware name: Intel Corporation 2012 Client Platform/Emerald Lake 2, BIOS ACRVMBY1.86C.0078.P00.1201161002 01/16/2012 [30129.876650] Call Trace: [30129.876650] dump_stack+0x9d/0xe0 [30129.876651] check_noncircular+0x34f/0x410 [30129.876653] __lock_acquire+0x2f70/0x4e90 [30129.876656] lock_acquire+0x1ac/0xad0 [30129.876658] console_unlock+0x460/0xa90 [30129.876660] vprintk_emit+0x130/0x420 [30129.876660] printk+0x9f/0xc5 [30129.876661] show_pwq+0x154/0x618 [30129.876662] show_workqueue_state.cold.55+0x193/0x6ca [30129.876664] __handle_sysrq+0x244/0x460 [30129.876665] write_sysrq_trigger+0x48/0x4a [30129.876665] proc_reg_write+0x1a6/0x240 [30129.876666] vfs_write+0x1a8/0x650 It looks like the commit was aimed to protect tty_insert_flip_string and there is no need for tty_flip_buffer_push to be under this lock. Fixes: b6da31b2c07c ("tty: Fix data race in tty_insert_flip_string_fixed_flag") Signed-off-by: Artem Savkov <asavkov@redhat.com> Acked-by: Jiri Slaby <jirislaby@kernel.org> Link: https://lore.kernel.org/r/20200902120045.3693075-1-asavkov@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-18tty: fix kernel-docJiri Slaby1-1/+1
With W=1, the kernel-doc checker complains quite a lot in the tty layer. Over the time, many documented parameters were renamed, removed or switched from tty to tty_port and similar. Some were mistyped in the doc too. So fix all these in the tty core. (But do not add the missing ones which the checker complains about too. Not now.) The rest in the tty layer will follow in the next patches. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200818085655.12071-4-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-13pty: fix compat ioctlsAl Viro1-2/+12
pointer-taking ones need compat_ptr(); int-taking one doesn't. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-07-21pty: fix O_CLOEXEC for TIOCGPTPEERMatthijs van Duin1-1/+1
It was being ignored because the flags were not passed to fd allocation. Fixes: 54ebbfb16034 ("tty: add TIOCGPTPEER ioctl") Signed-off-by: Matthijs van Duin <matthijsvanduin@gmail.com> Acked-by: Aleksa Sarai <asarai@suse.de> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-14tty: Fix data race in tty_insert_flip_string_fixed_flagDaeRyong Jeong1-0/+3
Unlike normal serials, in pty layer, there is no guarantee that multiple threads don't insert input characters at the same time. If it is happened, tty_insert_flip_string_fixed_flag can be executed concurrently. This can lead slab out-of-bounds write in tty_insert_flip_string_fixed_flag. Call sequences are as follows. CPU0 CPU1 n_tty_ioctl_helper n_tty_ioctl_helper __start_tty tty_send_xchar tty_wakeup pty_write n_hdlc_tty_wakeup tty_insert_flip_string n_hdlc_send_frames tty_insert_flip_string_fixed_flag pty_write tty_insert_flip_string tty_insert_flip_string_fixed_flag To fix the race, acquire port->lock in pty_write() before it inserts input characters to tty buffer. It prevents multiple threads from inserting input characters concurrently. The crash log is as follows: BUG: KASAN: slab-out-of-bounds in tty_insert_flip_string_fixed_flag+0xb5/ 0x130 drivers/tty/tty_buffer.c:316 at addr ffff880114fcc121 Write of size 1792 by task syz-executor0/30017 CPU: 1 PID: 30017 Comm: syz-executor0 Not tainted 4.8.0 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014 0000000000000000 ffff88011638f888 ffffffff81694cc3 ffff88007d802140 ffff880114fcb300 ffff880114fcc300 ffff880114fcb300 ffff88011638f8b0 ffffffff8130075c ffff88011638f940 ffff88007d802140 ffff880194fcc121 Call Trace: __dump_stack lib/dump_stack.c:15 [inline] dump_stack+0xb3/0x110 lib/dump_stack.c:51 kasan_object_err+0x1c/0x70 mm/kasan/report.c:156 print_address_description mm/kasan/report.c:194 [inline] kasan_report_error+0x1f7/0x4e0 mm/kasan/report.c:283 kasan_report+0x36/0x40 mm/kasan/report.c:303 check_memory_region_inline mm/kasan/kasan.c:292 [inline] check_memory_region+0x13e/0x1a0 mm/kasan/kasan.c:299 memcpy+0x37/0x50 mm/kasan/kasan.c:335 tty_insert_flip_string_fixed_flag+0xb5/0x130 drivers/tty/tty_buffer.c:316 tty_insert_flip_string include/linux/tty_flip.h:35 [inline] pty_write+0x7f/0xc0 drivers/tty/pty.c:115 n_hdlc_send_frames+0x1d4/0x3b0 drivers/tty/n_hdlc.c:419 n_hdlc_tty_wakeup+0x73/0xa0 drivers/tty/n_hdlc.c:496 tty_wakeup+0x92/0xb0 drivers/tty/tty_io.c:601 __start_tty.part.26+0x66/0x70 drivers/tty/tty_io.c:1018 __start_tty+0x34/0x40 drivers/tty/tty_io.c:1013 n_tty_ioctl_helper+0x146/0x1e0 drivers/tty/tty_ioctl.c:1138 n_hdlc_tty_ioctl+0xb3/0x2b0 drivers/tty/n_hdlc.c:794 tty_ioctl+0xa85/0x16d0 drivers/tty/tty_io.c:2992 vfs_ioctl fs/ioctl.c:43 [inline] do_vfs_ioctl+0x13e/0xba0 fs/ioctl.c:679 SYSC_ioctl fs/ioctl.c:694 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 entry_SYSCALL_64_fastpath+0x1f/0xbd Signed-off-by: DaeRyong Jeong <threeearcat@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-02-12vfs: do bulk POLL* -> EPOLL* replacementLinus Torvalds1-2/+2
This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script: for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'` for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done done with de-mangling cleanups yet to come. NOTE! On almost all architectures, the EPOLL* constants have the same values as the POLL* constants do. But they keyword here is "almost". For various bad reasons they aren't the same, and epoll() doesn't actually work quite correctly in some cases due to this on Sparc et al. The next patch from Al will sort out the final differences, and we should be all done. Scripted-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman1-0/+1
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-09-05Merge tag 'tty-4.14-rc1' of ↵Linus Torvalds1-1/+7
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty/serial updates from Greg KH: "Here is the big tty/serial driver update for 4.14-rc1. Well, not all that big, just a number of small serial driver fixes, and a new serial driver. Also in here are some much needed goldfish tty driver (emulator) fixes to try to get that codebase under control. All of these have been in linux-next for a while with no reported issues" * tag 'tty-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (94 commits) tty: goldfish: Implement support for kernel 'earlycon' parameter tty: goldfish: Use streaming DMA for r/w operations on Ranchu platforms tty: goldfish: Refactor constants to better reflect their nature serial: 8250_port: Remove useless NULL checks earlycon: initialise baud field of earlycon device structure tty: hvcs: make ktermios const pty: show associative slave of ptmx in fdinfo tty: n_gsm: Add compat_ioctl tty: hvcs: constify vio_device_id tty: hvc_vio: constify vio_device_id tty: mips_ejtag_fdc: constify mips_cdmm_device_id Introduce 8250_men_mcb mcb: introduce mcb_get_resource() serial: imx: Avoid post-PIO cleanup if TX DMA is started tty: serial: imx: disable irq after suspend serial: 8250_uniphier: add suspend/resume support serial: 8250_uniphier: use CHAR register for canary to detect power-off serial: 8250_uniphier: fix serial port index in private data serial: 8250: of: Add new port type for MediaTek BTIF controller on MT7622/23 SoC dt-bindings: serial: 8250: Add MediaTek BTIF controller bindings ...
2017-08-28pty: show associative slave of ptmx in fdinfoMasatake YAMATO1-1/+7
This patch adds "tty-index" field to /proc/PID/fdinfo/N if N specifies /dev/ptmx. The field shows the index of associative slave pts. Though a minor number is given for each pts instance, ptmx is not. It means there is no way in user-space to know the association between file descriptors for pts/n and ptmx. (n = 0, 1, ...) This is different from pipe. About pipe such association can be solved by inode of pipefs. Providing the way to know the association between pts/n and ptmx helps users understand the status of running system. lsof can utilize this field. Signed-off-by: Masatake YAMATO <yamato@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-08-24pty: Repair TIOCGPTPEEREric W. Biederman1-37/+27
The implementation of TIOCGPTPEER has two issues. When /dev/ptmx (as opposed to /dev/pts/ptmx) is opened the wrong vfsmount is passed to dentry_open. Which results in the kernel displaying the wrong pathname for the peer. The second is simply by caching the vfsmount and dentry of the peer it leaves them open, in a way they were not previously Which because of the inreased reference counts can cause unnecessary behaviour differences resulting in regressions. To fix these move the ioctl into tty_io.c at a generic level allowing the ioctl to have access to the struct file on which the ioctl is being called. This allows the path of the slave to be derived when opening the slave through TIOCGPTPEER instead of requiring the path to the slave be cached. Thus removing the need for caching the path. A new function devpts_ptmx_path is factored out of devpts_acquire and used to implement a function devpts_mntget. The new function devpts_mntget takes a filp to perform the lookup on and fsi so that it can confirm that the superblock that is found by devpts_ptmx_path is the proper superblock. v2: Lots of fixes to make the code actually work v3: Suggestions by Linus - Removed the unnecessary initialization of filp in ptm_open_peer - Simplified devpts_ptmx_path as gotos are no longer required [ This is the fix for the issue that was reverted in commit 143c97cc6529, but this time without breaking 'pbuilder' due to increased reference counts - Linus ] Fixes: 54ebbfb16034 ("tty: add TIOCGPTPEER ioctl") Reported-by: Christian Brauner <christian.brauner@canonical.com> Reported-and-tested-by: Stefan Lippers-Hollmann <s.l-h@gmx.de> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-24Revert "pty: fix the cached path of the pty slave file descriptor in the master"Linus Torvalds1-5/+2
This reverts commit c8c03f1858331e85d397bacccd34ef409aae993c. It turns out that while fixing the ptmx file descriptor to have the correct 'struct path' to the associated slave pty is a really good thing, it breaks some user space tools for a very annoying reason. The problem is that /dev/ptmx and its associated slave pty (/dev/pts/X) are on different mounts. That was what caused us to have the wrong path in the first place (we would mix up the vfsmount of the 'ptmx' node, with the dentry of the pty slave node), but it also means that now while we use the right vfsmount, having the pty master open also keeps the pts mount busy. And it turn sout that that makes 'pbuilder' very unhappy, as noted by Stefan Lippers-Hollmann: "This patch introduces a regression for me when using pbuilder 0.228.7[2] (a helper to build Debian packages in a chroot and to create and update its chroots) when trying to umount /dev/ptmx (inside the chroot) on Debian/ unstable (full log and pbuilder configuration file[3] attached). [...] Setting up build-essential (12.3) ... Processing triggers for libc-bin (2.24-15) ... I: unmounting dev/ptmx filesystem W: Could not unmount dev/ptmx: umount: /var/cache/pbuilder/build/1340/dev/ptmx: target is busy (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1).)" apparently pbuilder tries to unmount the /dev/pts filesystem while still holding at least one master node open, which is arguably not very nice, but we don't break user space even when fixing other bugs. So this commit has to be reverted. I'll try to figure out a way to avoid caching the path to the slave pty in the master pty. The only thing that actually wants that slave pty path is the "TIOCGPTPEER" ioctl, and I think we could just recreate the path at that time. Reported-by: Stefan Lippers-Hollmann <s.l-h@gmx.de> Cc: Eric W Biederman <ebiederm@xmission.com> Cc: Christian Brauner <christian.brauner@canonical.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-17pty: fix the cached path of the pty slave file descriptor in the masterLinus Torvalds1-2/+5
Christian Brauner reported that if you use the TIOCGPTPEER ioctl() to get a slave pty file descriptor, the resulting file descriptor doesn't look right in /proc/<pid>/fd/<fd>. In particular, he wanted to use readlink() on /proc/self/fd/<fd> to get the pathname of the slave pty (basically implementing "ptsname{_r}()"). The reason for that was that we had generated the wrong 'struct path' when we create the pty in ptmx_open(). In particular, the dentry was correct, but the vfsmount pointed to the mount of the ptmx node. That _can_ be correct - in case you use "/dev/pts/ptmx" to open the master - but usually is not. The normal case is to use /dev/ptmx, which then looks up the pts/ directory, and then the vfsmount of the ptmx node is obviously the /dev directory, not the /dev/pts/ directory. We actually did have the right vfsmount available, but in the wrong place (it gets looked up in 'devpts_acquire()' when we get a reference to the pts filesystem), and so ptmx_open() used the wrong mnt pointer. The end result of this confusion was that the pty worked fine, but when if you did TIOCGPTPEER to get the slave side of the pty, end end result would also work, but have that dodgy 'struct path'. And then when doing "d_path()" on to get the pathname, the vfsmount would not match the root of the pts directory, and d_path() would return an empty pathname thinking that the entry had escaped a bind mount into another mount. This fixes the problem by making devpts_acquire() return the vfsmount for the pts filesystem, allowing ptmx_open() to trivially just use the right mount for the pts dentry, and create the proper 'struct path'. Reported-by: Christian Brauner <christian.brauner@ubuntu.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Eric Biederman <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-17tty: hide unused pty_get_peer functionArnd Bergmann1-43/+42
TIOCGPTPEER is only used for unix98 PTYs, and we get a warning when those are disabled: drivers/tty/pty.c:466:12: error: 'pty_get_peer' defined but not used [-Werror=unused-function] This moves the respective functions inside of the existing #ifdef. Fixes: 54ebbfb16034 ("tty: add TIOCGPTPEER ioctl") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Aleksa Sarai <asarai@suse.de> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-09tty: add TIOCGPTPEER ioctlAleksa Sarai1-4/+67
When opening the slave end of a PTY, it is not possible for userspace to safely ensure that /dev/pts/$num is actually a slave (in cases where the mount namespace in which devpts was mounted is controlled by an untrusted process). In addition, there are several unresolvable race conditions if userspace were to attempt to detect attacks through stat(2) and other similar methods [in addition it is not clear how userspace could detect attacks involving FUSE]. Resolve this by providing an interface for userpace to safely open the "peer" end of a PTY file descriptor by using the dentry cached by devpts. Since it is not possible to have an open master PTY without having its slave exposed in /dev/pts this interface is safe. This interface currently does not provide a way to get the master pty (since it is not clear whether such an interface is safe or even useful). Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Valentin Rothberg <vrothberg@suse.com> Signed-off-by: Aleksa Sarai <asarai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-09tty: add compat_ioctl callbacksAleksa Sarai1-0/+22
In order to avoid future diversions between fs/compat_ioctl.c and drivers/tty/pty.c, define .compat_ioctl callbacks for the relevant tty_operations structs. Since both pty_unix98_ioctl() and pty_bsd_ioctl() are compatible between 32-bit and 64-bit userspace no special translation is required. Signed-off-by: Aleksa Sarai <asarai@suse.de> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-03-17tty: pty: Fix ldisc flush after userspace become aware of the data alreadyWang YanQing1-6/+1
While using emacs, cat or others' commands in konsole with recent kernels, I have met many times that CTRL-C freeze konsole. After konsole freeze I can't type anything, then I have to open a new one, it is very annoying. See bug report: https://bugs.kde.org/show_bug.cgi?id=175283 The platform in that bug report is Solaris, but now the pty in linux has the same problem or the same behavior as Solaris :) It has high possibility to trigger the problem follow steps below: Note: In my test, BigFile is a text file whose size is bigger than 1G 1:open konsole 1:cat BigFile 2:CTRL-C After some digging, I find out the reason is that commit 1d1d14da12e7 ("pty: Fix buffer flush deadlock") changes the behavior of pty_flush_buffer. Thread A Thread B -------- -------- 1:n_tty_poll return POLLIN 2:CTRL-C trigger pty_flush_buffer tty_buffer_flush n_tty_flush_buffer 3:attempt to check count of chars: ioctl(fd, TIOCINQ, &available) available is equal to 0 4:read(fd, buffer, avaiable) return 0 5:konsole close fd Yes, I know we could use the same patch included in the BUG report as a workaround for linux platform too. But I think the data in ldisc is belong to application of another side, we shouldn't clear it when we want to flush write buffer of this side in pty_flush_buffer. So I think it is better to disable ldisc flush in pty_flush_buffer, because its new hehavior bring no benefit except that it mess up the behavior between POLLIN, and TIOCINQ or FIONREAD. Also I find no flush_buffer function in others' tty driver has the same behavior as current pty_flush_buffer. Fixes: 1d1d14da12e7 ("pty: Fix buffer flush deadlock") CC: stable@vger.kernel.org # v4.0+ Signed-off-by: Wang YanQing <udknight@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar1-1/+1
<linux/sched/signal.h> We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/signal.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-09-15pty: make ptmx file ops read-only after initKees Cook1-1/+1
The ptmx_fops structure is only changed during init, so mark it as such. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-06-26devpts: fix null pointer dereference on failed memory allocationColin Ian King1-2/+5
An ENOMEM when creating a pair tty in tty_ldisc_setup causes a null pointer dereference in devpts_kill_index because tty->link->driver_data is NULL. The oops was triggered with the pty stressor in stress-ng when in a low memory condition. tty_init_dev tries to clean up a tty_ldisc_setup ENOMEM error by calling release_tty, however, this ultimately tries to clean up the NULL pair'd tty in pty_unix98_remove, triggering the Oops. Add check to pty_unix98_remove to only clean up fsi if it is not NULL. Ooops: [ 23.020961] Oops: 0000 [#1] SMP [ 23.020976] Modules linked in: ppdev snd_hda_codec_generic snd_hda_intel snd_hda_codec parport_pc snd_hda_core snd_hwdep parport snd_pcm input_leds joydev snd_timer serio_raw snd soundcore i2c_piix4 mac_hid ib_iser rdma_cm iw_cm ib_cm ib_core configfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel qxl aes_x86_64 ttm lrw gf128mul glue_helper ablk_helper drm_kms_helper cryptd syscopyarea sysfillrect psmouse sysimgblt floppy fb_sys_fops drm pata_acpi jitterentropy_rng drbg ansi_cprng [ 23.020978] CPU: 0 PID: 1452 Comm: stress-ng-pty Not tainted 4.7.0-rc4+ #2 [ 23.020978] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 [ 23.020979] task: ffff88007ba30000 ti: ffff880078ea8000 task.ti: ffff880078ea8000 [ 23.020981] RIP: 0010:[<ffffffff813f11ff>] [<ffffffff813f11ff>] ida_remove+0x1f/0x120 [ 23.020981] RSP: 0018:ffff880078eabb60 EFLAGS: 00010a03 [ 23.020982] RAX: 4444444444444567 RBX: 0000000000000000 RCX: 000000000000001f [ 23.020982] RDX: 000000000000014c RSI: 000000000000026f RDI: 0000000000000000 [ 23.020982] RBP: ffff880078eabb70 R08: 0000000000000004 R09: 0000000000000036 [ 23.020983] R10: 000000000000026f R11: 0000000000000000 R12: 000000000000026f [ 23.020983] R13: 000000000000026f R14: ffff88007c944b40 R15: 000000000000026f [ 23.020984] FS: 00007f9a2f3cc700(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000 [ 23.020984] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.020985] CR2: 0000000000000010 CR3: 000000006c81b000 CR4: 00000000001406f0 [ 23.020988] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.020988] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.020988] Stack: [ 23.020989] 0000000000000000 000000000000026f ffff880078eabb90 ffffffff812a5a99 [ 23.020990] 0000000000000000 00000000fffffff4 ffff880078eabba8 ffffffff814f9cbe [ 23.020991] ffff88007965c800 ffff880078eabbc8 ffffffff814eef43 fffffffffffffff4 [ 23.020991] Call Trace: [ 23.021000] [<ffffffff812a5a99>] devpts_kill_index+0x29/0x50 [ 23.021002] [<ffffffff814f9cbe>] pty_unix98_remove+0x2e/0x50 [ 23.021006] [<ffffffff814eef43>] release_tty+0xb3/0x1b0 [ 23.021007] [<ffffffff814f18d4>] tty_init_dev+0xd4/0x1c0 [ 23.021011] [<ffffffff814f9fae>] ptmx_open+0xae/0x190 [ 23.021013] [<ffffffff812254ef>] chrdev_open+0xbf/0x1b0 [ 23.021015] [<ffffffff8121d973>] do_dentry_open+0x203/0x310 [ 23.021016] [<ffffffff81225430>] ? cdev_put+0x30/0x30 [ 23.021017] [<ffffffff8121ee44>] vfs_open+0x54/0x80 [ 23.021018] [<ffffffff8122b8fc>] ? may_open+0x8c/0x100 [ 23.021019] [<ffffffff8122f26b>] path_openat+0x2eb/0x1440 [ 23.021020] [<ffffffff81230534>] ? putname+0x54/0x60 [ 23.021022] [<ffffffff814f6f97>] ? n_tty_ioctl_helper+0x27/0x100 [ 23.021023] [<ffffffff81231651>] do_filp_open+0x91/0x100 [ 23.021024] [<ffffffff81230596>] ? getname_flags+0x56/0x1f0 [ 23.021026] [<ffffffff8123fc66>] ? __alloc_fd+0x46/0x190 [ 23.021027] [<ffffffff8121f1e4>] do_sys_open+0x124/0x210 [ 23.021028] [<ffffffff8121f2ee>] SyS_open+0x1e/0x20 [ 23.021035] [<ffffffff81845576>] entry_SYSCALL_64_fastpath+0x1e/0xa8 [ 23.021044] Code: 63 28 45 31 e4 eb dd 0f 1f 44 00 00 55 4c 63 d6 48 ba 89 88 88 88 88 88 88 88 4c 89 d0 b9 1f 00 00 00 48 f7 e2 48 89 e5 41 54 53 <8b> 47 10 48 89 fb 8d 3c c5 00 00 00 00 48 c1 ea 09 b8 01 00 00 [ 23.021045] RIP [<ffffffff813f11ff>] ida_remove+0x1f/0x120 [ 23.021045] RSP <ffff880078eabb60> [ 23.021046] CR2: 0000000000000010 Signed-off-by: Colin Ian King <colin.king@canonical.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-06-05devpts: Make each mount of devpts an independent filesystem.Eric W. Biederman1-7/+8
The /dev/ptmx device node is changed to lookup the directory entry "pts" in the same directory as the /dev/ptmx device node was opened in. If there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx uses that filesystem. Otherwise the open of /dev/ptmx fails. The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that userspace can now safely depend on each mount of devpts creating a new instance of the filesystem. Each mount of devpts is now a separate and equal filesystem. Reserved ttys are now available to all instances of devpts where the mounter is in the initial mount namespace. A new vfs helper path_pts is introduced that finds a directory entry named "pts" in the directory of the passed in path, and changes the passed in path to point to it. The helper path_pts uses a function path_parent_directory that was factored out of follow_dotdot. In the implementation of devpts: - devpts_mnt is killed as it is no longer meaningful if all mounts of devpts are equal. - pts_sb_from_inode is replaced by just inode->i_sb as all cached inodes in the tty layer are now from the devpts filesystem. - devpts_add_ref is rolled into the new function devpts_ptmx. And the unnecessary inode hold is removed. - devpts_del_ref is renamed devpts_release and reduced to just a deacrivate_super. - The newinstance mount option continues to be accepted but is now ignored. In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as they are never used. Documentation/filesystems/devices.txt is updated to describe the current situation. This has been verified to work properly on openwrt-15.05, centos5, centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3, ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1, slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01. With the caveat that on centos6 and on slackware-14.1 that there wind up being two instances of the devpts filesystem mounted on /dev/pts, the lower copy does not end up getting used. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-09Merge 4.6-rc7 into tty-nextGreg Kroah-Hartman1-10/+8
We want the pty fixes in here as well so that patches can build on it. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-05-01Fix OpenSSH pty regression on closeBrian Bloniarz1-3/+1
OpenSSH expects the (non-blocking) read() of pty master to return EAGAIN only if it has received all of the slave-side output after it has received SIGCHLD. This used to work on pre-3.12 kernels. This fix effectively forces non-blocking read() and poll() to block for parallel i/o to complete for all ttys. It also unwinds these changes: 1) f8747d4a466ab2cafe56112c51b3379f9fdb7a12 tty: Fix pty master read() after slave closes 2) 52bce7f8d4fc633c9a9d0646eef58ba6ae9a3b73 pty, n_tty: Simplify input processing on final close 3) 1a48632ffed61352a7810ce089dc5a8bcd505a60 pty: Fix input race when closing Inspired by analysis and patch from Marc Aurele La France <tsi@tuyoix.net> Reported-by: Volth <openssh@volth.com> Reported-by: Marc Aurele La France <tsi@tuyoix.net> BugLink: https://bugzilla.mindrot.org/show_bug.cgi?id=52 BugLink: https://bugzilla.mindrot.org/show_bug.cgi?id=2492 Signed-off-by: Brian Bloniarz <brian.bloniarz@gmail.com> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-04-30tty: Replace TTY_IO_ERROR bit tests with tty_io_error()Peter Hurley1-1/+1
Abstract TTY_IO_ERROR status test treewide with tty_io_error(). NB: tty->flags uses atomic bit ops; replace non-atomic bit test with test_bit(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-04-27devpts: more pty driver interface cleanupsLinus Torvalds1-10/+8
This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-18devpts: clean up interface to pty driversLinus Torvalds1-33/+30
This gets rid of the horrible notion of having that struct inode *ptmx_inode be the linchpin of the interface between the pty code and devpts. By de-emphasizing the ptmx inode, a lot of things actually get cleaner, and we will have a much saner way forward. In particular, this will allow us to associate with any particular devpts instance at open-time, and not be artificially tied to one particular ptmx inode. The patch itself is actually fairly straightforward, and apart from some locking and return path cleanups it's pretty mechanical: - the interfaces that devpts exposes all take "struct pts_fs_info *" instead of "struct inode *ptmx_inode" now. NOTE! The "struct pts_fs_info" thing is a completely opaque structure as far as the pty driver is concerned: it's still declared entirely internally to devpts. So the pty code can't actually access it in any way, just pass it as a "cookie" to the devpts code. - the "look up the pts fs info" is now a single clear operation, that also does the reference count increment on the pts superblock. So "devpts_add/del_ref()" is gone, and replaced by a "lookup and get ref" operation (devpts_get_ref(inode)), along with a "put ref" op (devpts_put_ref()). - the pty master "tty->driver_data" field now contains the pts_fs_info, not the ptmx inode. - because we don't care about the ptmx inode any more as some kind of base index, the ref counting can now drop the inode games - it just gets the ref on the superblock. - the pts_fs_info now has a back-pointer to the super_block. That's so that we can easily look up the information we actually need. Although quite often, the pts fs info was actually all we wanted, and not having to look it up based on some magical inode makes things more straightforward. In particular, now that "devpts_get_ref(inode)" operation should really be the *only* place we need to look up what devpts instance we're associated with, and we do it exactly once, at ptmx_open() time. The other side of this is that one ptmx node could now be associated with multiple different devpts instances - you could have a single /dev/ptmx node, and then have multiple mount namespaces with their own instances of devpts mounted on /dev/pts/. And that's all perfectly sane in a model where we just look up the pts instance at open time. This will eventually allow us to get rid of our odd single-vs-multiple pts instance model, but this patch in itself changes no semantics, only an internal binding model. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-02-15Merge 4.5-rc4 into tty-nextGreg Kroah-Hartman1-1/+20
We want the fixes in here, and this resolves a merge error in tty_io.c Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-07pty: make sure super_block is still valid in final /dev/tty closeHerton R. Krzesinski1-3/+6
Considering current pty code and multiple devpts instances, it's possible to umount a devpts file system while a program still has /dev/tty opened pointing to a previosuly closed pty pair in that instance. In the case all ptmx and pts/N files are closed, umount can be done. If the program closes /dev/tty after umount is done, devpts_kill_index will use now an invalid super_block, which was already destroyed in the umount operation after running ->kill_sb. This is another "use after free" type of issue, but now related to the allocated super_block instance. To avoid the problem (warning at ida_remove and potential crashes) for this specific case, I added two functions in devpts which grabs additional references to the super_block, which pty code now uses so it makes sure the super block structure is still valid until pty shutdown is done. I also moved the additional inode references to the same functions, which also covered similar case with inode being freed before /dev/tty final close/shutdown. Signed-off-by: Herton R. Krzesinski <herton@redhat.com> Cc: stable@vger.kernel.org # 2.6.29+ Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-07pty: fix possible use after free of tty->driver_dataHerton R. Krzesinski1-1/+17
This change fixes a bug for a corner case where we have the the last release from a pty master/slave coming from a previously opened /dev/tty file. When this happens, the tty->driver_data can be stale, due to all ptmx or pts/N files having already been closed before (and thus the inode related to these files, which tty->driver_data points to, being already freed/destroyed). The fix here is to keep a reference on the opened master ptmx inode. We maintain the inode referenced until the final pty_unix98_shutdown, and only pass this inode to devpts_kill_index. Signed-off-by: Herton R. Krzesinski <herton@redhat.com> Cc: <stable@vger.kernel.org> # 2.6.29+ Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-01-29tty: Use termios c_*flag macrosPeter Hurley1-2/+1
Expressions of the form "tty->termios.c_*flag & FLAG" are more clearly expressed with the termios flags macros, I_FLAG(), C_FLAG(), O_FLAG(), and L_FLAG(). Convert treewide. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-01-28pty: Remove pty_unix98_shutdown()Peter Hurley1-10/+1
The tty core invokes the optional driver shutdown() just before the optional driver remove() (shutdown() has access to the termios and remove() does not). Because pty drivers must prevent the default remove() action, the Unix98 pty drivers define a dummy remove() function. Instead, release the slave index in the remove() method and delete the optional shutdown() method. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-01-28tty: Fix tty_init_termios() declarationPeter Hurley1-12/+3
tty_init_termios() never returns an error; re-declare as void. Remove unnecessary error handling from callers. Remove extern declarations of tty_free_termios() and free_tty_struct() and re-declare in file scope. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-01-28tty: Fix ldisc leak in failed tty_init_dev()Peter Hurley1-3/+2
release_tty() leaks the ldisc instance when called directly (rather than when releasing the file descriptor from tty_release()). Since tty_ldisc_release() clears tty->ldisc, releasing the ldisc instance at tty teardown if tty->ldisc is non-null is not in danger of double-releasing the ldisc. Remove deinitialize_tty_struct() now that free_tty_struct() always performs the tty_ldisc_deinit(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-12-14tty: Remove __func__ from tty_debug() macroPeter Hurley1-1/+1
Now that tty_debug() macro uses pr_debug(), the function name can be printed when using dynamic debug; printing the function name within the format string is redundant. Remove the __func__ parameter and print specifier from the format string. Add context to messages for when the function name is not printed by dynamic debug, or when dynamic debug is not enabled. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-10-04drivers/tty: make pty.c slightly more explicitly non-modularPaul Gortmaker1-2/+5
The Kconfig currently controlling compilation of this code is: drivers/tty/Kconfig:config LEGACY_PTYS drivers/tty/Kconfig: bool "Legacy (BSD) PTY support" ...and: drivers/tty/Kconfig:config UNIX98_PTYS drivers/tty/Kconfig: bool "Unix98 PTY support" if EXPERT combined with this: obj-$(CONFIG_LEGACY_PTYS) += pty.o obj-$(CONFIG_UNIX98_PTYS) += pty.o ...meaning that it currently is not being built as a module by anyone. Lets remove the traces of modularity we can so that when reading the driver there is less doubt it is builtin-only. Since module_init translates to device_initcall in the non-modular case, the init ordering remains unchanged with this commit. We don't delete the module.h include since other parts of the file are using content from there. Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jslaby@suse.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-07-24pty: Add debug message for ptmx openPeter Hurley1-0/+8
Opens of /dev/ptmx don't use tty_open() so debug messages are not printed for those opens; print a debug message with the open count (which must always be 1) if TTY_DEBUG_HANGUP is defined. NB: Each tty core source file undefs support for debug messages. The relevant source file must be patched/edited to enable these messages. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-10pty: Fix input race when closingPeter Hurley1-2/+3
A read() from a pty master may mistakenly indicate EOF (errno == -EIO) after the pty slave has closed, even though input data remains to be read. For example, pty slave | input worker | pty master | | | | n_tty_read() pty_write() | | input avail? no add data | | sleep schedule worker --->| | . |---> flush_to_ldisc() | . pty_close() | fill read buffer | . wait for worker | wakeup reader --->| . | read buffer full? |---> input avail ? yes |<--- yes - exit worker | copy 4096 bytes to user TTY_OTHER_CLOSED <---| |<--- kick worker | | **** New read() before worker starts **** | | n_tty_read() | | input avail? no | | TTY_OTHER_CLOSED? yes | | return -EIO Several conditions are required to trigger this race: 1. the ldisc read buffer must become full so the input worker exits 2. the read() count parameter must be >= 4096 so the ldisc read buffer is empty 3. the subsequent read() occurs before the kicked worker has processed more input However, the underlying cause of the race is that data is pipelined, while tty state is not; ie., data already written by the pty slave end is not yet visible to the pty master end, but state changes by the pty slave end are visible to the pty master end immediately. Pipeline the TTY_OTHER_CLOSED state through input worker to the reader. 1. Introduce TTY_OTHER_DONE which is set by the input worker when TTY_OTHER_CLOSED is set and either the input buffers are flushed or input processing has completed. Readers/polls are woken when TTY_OTHER_DONE is set. 2. Reader/poll checks TTY_OTHER_DONE instead of TTY_OTHER_CLOSED. 3. A new input worker is started from pty_close() after setting TTY_OTHER_CLOSED, which ensures the TTY_OTHER_DONE state will be set if the last input worker is already finished (or just about to exit). Remove tty_flush_to_ldisc(); no in-tree callers. Fixes: 52bce7f8d4fc ("pty, n_tty: Simplify input processing on final close") Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=96311 BugLink: http://bugs.launchpad.net/bugs/1429756 Cc: <stable@vger.kernel.org> # 3.19+ Reported-by: Andy Whitcroft <apw@canonical.com> Reported-by: H.J. Lu <hjl.tools@gmail.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-02n_tty: Fix signal handling flushesPeter Hurley1-0/+1
BRKINT and ISIG requires input and output flush when a signal char is received. However, the order of operations is significant since parallel i/o may be ongoing. Merge the signal handling for BRKINT with ISIG handling. Process the signal first. This ensures any ongoing i/o is aborted; without this, a waiting writer may continue writing after the flush occurs and after the signal char has been echoed. Write lock the termios_rwsem, which excludes parallel writers from pushing new i/o until after the output buffers are flushed; claiming the write lock is necessary anyway to exclude parallel readers while the read buffer is flushed. Subclass the termios_rwsem for ptys since the slave pty performing the flush may appear to reorder the termios_rwsem->tty buffer lock lock order; adding annotation clarifies that slave tty_buffer lock-> slave termios_rwsem -> master tty_buffer lock is a valid lock order. Flush the echo buffer. In this context, the echo buffer is 'output'. Otherwise, the output will appear discontinuous because the output buffer was cleared which contains older output than the echo buffer. Open-code the read buffer flush since the input worker does not need kicking (this is the input worker). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-02pty: Fix buffer flush deadlockPeter Hurley1-1/+9
The pty driver does not clear its write buffer when commanded. This is to avoid an apparent deadlock between parallel flushes from both pty ends; specifically when handling either BRK or INTR input. However, parallel flushes from this source is not possible since the pty master can never be set to BRKINT or ISIG. Parallel flushes from other sources are possible but these do not threaten deadlocks. Annotate the tty buffer mutex for lockdep to represent the nested tty_buffer locking which occurs when the pty slave is processing input (its buffer mutex held) and receives INTR or BRK and acquires the linked tty buffer mutex via tty_buffer_flush(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-02pty: Fix overlimit memory usePeter Hurley1-14/+3
The pty_space() computation is broken; the space already consumed in the tty buffer is not accounted for. Use tty_buffer_set_limit(), which enforces the limit automatically. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-02-02tty: Prevent untrappable signals from malicious programPeter Hurley1-0/+3
Commit 26df6d13406d1a5 ("tty: Add EXTPROC support for LINEMODE") allows a process which has opened a pty master to send _any_ signal to the process group of the pty slave. Although potentially exploitable by a malicious program running a setuid program on a pty slave, it's unknown if this exploit currently exists. Limit to signals actually used. Cc: Theodore Ts'o <tytso@mit.edu> Cc: Howard Chu <hyc@symas.com> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jiri Slaby <jslaby@suse.cz> Cc: <stable@vger.kernel.org> # 2.6.36+ Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-06pty, n_tty: Simplify input processing on final closePeter Hurley1-0/+1
When releasing one end of a pty pair, that end may just have written to the other, which the input processing worker, flush_to_ldisc(), is still working on but has not completed the copy to the other end's read buffer. So input may not appear to be available to a waiting reader but yet TTY_OTHER_CLOSED is now observed. The n_tty line discipline has worked around this by waiting for input processing to complete and then re-checking if input is available before exiting with -EIO. Since the tty/ldisc lock reordering, the wait for input processing to complete can now occur during final close before setting TTY_OTHER_CLOSED. In this way, a waiting reader is guaranteed to see input available (if any) before observing TTY_OTHER_CLOSED. 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>
2014-11-06pty: Don't drop pty master tty lock to hangup slavePeter Hurley1-2/+0
With the revised tty lock order and lockdep annotation, claiming the pty slave lock is now safe while still holding the pty master lock. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-06tty: Preset lock subclass for nested tty locksPeter Hurley1-0/+2
Eliminate the requirement of specifying the tty lock nesting at lock time; instead, set the lock subclass for slave ptys at pty install (normal ttys and master ptys use subclass 0). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-06pty: Always return -EIO if slave BSD pty opened firstPeter Hurley1-2/+5
Opening the slave BSD pty first already returns -EIO from the slave pty_open(), which in turn causes the newly installed tty pair to be released before returning from tty_open(). However, this can also cause a parallel master BSD pty open to fail because the pty pair destruction may already been taking place in tty_release(). Failing at driver->install() if the slave pty is opened first ensures that a pty master open cannot fail, because the driver tables will not have been updated so tty_driver_lookup_tty() won't find the master pty (and attempt to "re-open" it). In turn, this guarantees that any tty with a tty->count == 0 is in final close (rather than never opened). 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>
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