kernel/linux.git/drivers/tty/tty_ldisc.c, branch v5.10.257

tty: ldsic: fix tty_ldisc_autoload sysctl's proc_handler

2024-12-14T18:48:09+00:00

commit 635a9fca54f4f4148be1ae1c7c6bd37af80f5773 upstream. Commit 7c0cca7c847e ("tty: ldisc: add sysctl to prevent autoloading of ldiscs") introduces the tty_ldisc_autoload sysctl with the wrong proc_handler. .extra1 and .extra2 parameters are set to avoid other values thant SYSCTL_ZERO or SYSCTL_ONE to be set but proc_dointvec do not uses them. This commit fixes this by using proc_dointvec_minmax instead of proc_dointvec. Fixes: 7c0cca7c847e ("tty: ldisc: add sysctl to prevent autoloading of ldiscs") Cc: stable Signed-off-by: Nicolas Bouchinet Reviewed-by: Lin Feng Reviewed-by: Jiri Slaby Link: https://lore.kernel.org/r/20241112131357.49582-4-nicolas.bouchinet@clip-os.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman

tty: create internal tty.h file

2023-05-17T09:48:08+00:00

[ Upstream commit 98602c010ceba82f2c2384122dbd07bc965fd367 ] 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 Cc: Jiri Slaby Link: https://lore.kernel.org/r/20210408125134.3016837-2-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman Stable-dep-of: 094fb49a2d0d ("tty: Prevent writing chars during tcsetattr TCSADRAIN/FLUSH") Signed-off-by: Sasha Levin

tty: fix kernel-doc

2020-08-18T11:51:18+00:00

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 Link: https://lore.kernel.org/r/20200818085655.12071-4-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty_ldisc: simplify tty_ldisc_autoload initialization

2019-10-04T13:11:25+00:00

We have got existing macro to check for CONFIG option, use it. Signed-off-by: Pavel Machek Link: https://lore.kernel.org/r/20190924083244.GA4344@amd Signed-off-by: Greg Kroah-Hartman

proc/sysctl: add shared variables for range check

2019-07-19T00:08:07+00:00

In the sysctl code the proc_dointvec_minmax() function is often used to validate the user supplied value between an allowed range. This function uses the extra1 and extra2 members from struct ctl_table as minimum and maximum allowed value. On sysctl handler declaration, in every source file there are some readonly variables containing just an integer which address is assigned to the extra1 and extra2 members, so the sysctl range is enforced. The special values 0, 1 and INT_MAX are very often used as range boundary, leading duplication of variables like zero=0, one=1, int_max=INT_MAX in different source files: $ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l 248 Add a const int array containing the most commonly used values, some macros to refer more easily to the correct array member, and use them instead of creating a local one for every object file. This is the bloat-o-meter output comparing the old and new binary compiled with the default Fedora config: # scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164) Data old new delta sysctl_vals - 12 +12 __kstrtab_sysctl_vals - 12 +12 max 14 10 -4 int_max 16 - -16 one 68 - -68 zero 128 28 -100 Total: Before=20583249, After=20583085, chg -0.00% [mcroce@redhat.com: tipc: remove two unused variables] Link: http://lkml.kernel.org/r/20190530091952.4108-1-mcroce@redhat.com [akpm@linux-foundation.org: fix net/ipv6/sysctl_net_ipv6.c] [arnd@arndb.de: proc/sysctl: make firmware loader table conditional] Link: http://lkml.kernel.org/r/20190617130014.1713870-1-arnd@arndb.de [akpm@linux-foundation.org: fix fs/eventpoll.c] Link: http://lkml.kernel.org/r/20190430180111.10688-1-mcroce@redhat.com Signed-off-by: Matteo Croce Signed-off-by: Arnd Bergmann Acked-by: Kees Cook Reviewed-by: Aaron Tomlin Cc: Matthew Wilcox Cc: Stephen Rothwell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

locking/lockdep: Rename lockdep_assert_held_exclusive() -> lockdep_assert_held_write()

2019-06-17T10:09:24+00:00

All callers of lockdep_assert_held_exclusive() use it to verify the correct locking state of either a semaphore (ldisc_sem in tty, mmap_sem for perf events, i_rwsem of inode for dax) or rwlock by apparmor. Thus it makes sense to rename _exclusive to _write since that's the semantics callers care. Additionally there is already lockdep_assert_held_read(), which this new naming is more consistent with. No functional changes. Signed-off-by: Nikolay Borisov Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20190531100651.3969-1-nborisov@suse.com Signed-off-by: Ingo Molnar

tty: ldisc: add sysctl to prevent autoloading of ldiscs

2019-01-30T08:31:30+00:00

By default, the kernel will automatically load the module of any line dicipline that is asked for. As this sometimes isn't the safest thing to do, provide a sysctl to disable this feature. By default, we set this to 'y' as that is the historical way that Linux has worked, and we do not want to break working systems. But in the future, perhaps this can default to 'n' to prevent this functionality. Signed-off-by: Greg Kroah-Hartman Reviewed-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman

tty/ldsem: Add lockdep asserts for ldisc_sem

2018-12-05T11:16:33+00:00

Make sure under CONFIG_LOCKDEP that each change to line discipline is done with held write semaphor. Otherwise potential reader will have a good time dereferencing incomplete/uninitialized ldisc. An exception here is tty_ldisc_open(), as it's called without ldisc_sem locked by tty_init_dev() => tty_ldisc_setup() for the tty->link. It seem valid as tty_init_dev() will call tty_driver_install_tty() which will find ops->install(). Install will establish tty->link in pty_common_install(), just after allocation of slave tty with alloc_tty_struct(). So, no one should have a reference to slave pty yet. Cc: Jiri Slaby Cc: Peter Zijlstra Signed-off-by: Dmitry Safonov Signed-off-by: Greg Kroah-Hartman

tty: Don't block on IO when ldisc change is pending

2018-12-05T11:16:33+00:00

There might be situations where tty_ldisc_lock() has blocked, but there is already IO on tty and it prevents line discipline changes. It might theoretically turn into dead-lock. Basically, provide more priority to pending tty_ldisc_lock() than to servicing reads/writes over tty. User-visible issue was reported by Mikulas where on pa-risc with Debian 5 reboot took either 80 seconds, 3 minutes or 3:25 after proper locking in tty_reopen(). Cc: Jiri Slaby Reported-by: Mikulas Patocka Signed-off-by: Dmitry Safonov Signed-off-by: Greg Kroah-Hartman

proc: introduce proc_create_seq{,_data}

2018-05-16T05:23:35+00:00

Variants of proc_create{,_data} that directly take a struct seq_operations argument and drastically reduces the boilerplate code in the callers. All trivial callers converted over. Signed-off-by: Christoph Hellwig