commit 26f204380a3c182e5adf1a798db0724d6111b597 upstream.
The fcntl's F_SETOWN command sets the process that handle SIGIO/SIGURG
for the related file descriptor. Before this change, the
file_set_fowner LSM hook was always called, ignoring the VFS logic which
may not actually change the process that handles SIGIO (e.g. TUN, TTY,
dnotify), nor update the related UID/EUID.
Moreover, because security_file_set_fowner() was called without lock
(e.g. f_owner.lock), concurrent F_SETOWN commands could result to a race
condition and inconsistent LSM states (e.g. SELinux's fown_sid) compared
to struct fown_struct's UID/EUID.
This change makes sure the LSM states are always in sync with the VFS
state by moving the security_file_set_fowner() call close to the
UID/EUID updates and using the same f_owner.lock .
Rename f_modown() to __f_setown() to simplify code.
Cc: stable@vger.kernel.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: James Morris <jmorris@namei.org>
Cc: Jann Horn <jannh@google.com>
Cc: Ondrej Mosnacek <omosnace@redhat.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit f671a691e299f58835d4660d642582bf0e8f6fda ]
Syzbot reports a potential deadlock in do_fcntl:
========================================================
WARNING: possible irq lock inversion dependency detected
5.12.0-syzkaller #0 Not tainted
--------------------------------------------------------
syz-executor132/8391 just changed the state of lock:
ffff888015967bf8 (&f->f_owner.lock){.+..}-{2:2}, at: f_getown_ex fs/fcntl.c:211 [inline]
ffff888015967bf8 (&f->f_owner.lock){.+..}-{2:2}, at: do_fcntl+0x8b4/0x1200 fs/fcntl.c:395
but this lock was taken by another, HARDIRQ-safe lock in the past:
(&dev->event_lock){-...}-{2:2}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
Chain exists of:
&dev->event_lock --> &new->fa_lock --> &f->f_owner.lock
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&f->f_owner.lock);
local_irq_disable();
lock(&dev->event_lock);
lock(&new->fa_lock);
<Interrupt>
lock(&dev->event_lock);
*** DEADLOCK ***
This happens because there is a lock hierarchy of
&dev->event_lock --> &new->fa_lock --> &f->f_owner.lock
from the following call chain:
input_inject_event():
spin_lock_irqsave(&dev->event_lock,...);
input_handle_event():
input_pass_values():
input_to_handler():
evdev_events():
evdev_pass_values():
spin_lock(&client->buffer_lock);
__pass_event():
kill_fasync():
kill_fasync_rcu():
read_lock(&fa->fa_lock);
send_sigio():
read_lock_irqsave(&fown->lock,...);
However, since &dev->event_lock is HARDIRQ-safe, interrupts have to be
disabled while grabbing &f->f_owner.lock, otherwise we invert the lock
hierarchy.
Hence, we replace calls to read_lock/read_unlock on &f->f_owner.lock,
with read_lock_irq/read_unlock_irq.
Reported-and-tested-by: syzbot+e6d5398a02c516ce5e70@syzkaller.appspotmail.com
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit cc4a3f885e8f2bc3c86a265972e94fef32d68f67 ]
Currently there is no way to differentiate the file with alive owner
from the file with dead owner but pid of the owner reused. That's why
CRIU can't actually know if it needs to restore file owner or not,
because if it restores owner but actual owner was dead, this can
introduce unexpected signals to the "false"-owner (which reused the
pid).
Let's change the api, so that F_GETOWN(EX) returns 0 in case actual
owner is dead already. This comports with the POSIX spec, which
states that a PID of 0 indicates that no signal will be sent.
Cc: Jeff Layton <jlayton@kernel.org>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Stable-dep-of: f671a691e299 ("fcntl: fix potential deadlocks for &fown_struct.lock")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 2f488f698fda820f8e6fa0407630154eceb145d6 ]
There is an existing lock hierarchy of
&dev->event_lock --> &fasync_struct.fa_lock --> &f->f_owner.lock
from the following call chain:
input_inject_event():
spin_lock_irqsave(&dev->event_lock,...);
input_handle_event():
input_pass_values():
input_to_handler():
evdev_events():
evdev_pass_values():
spin_lock(&client->buffer_lock);
__pass_event():
kill_fasync():
kill_fasync_rcu():
read_lock(&fa->fa_lock);
send_sigio():
read_lock_irqsave(&fown->lock,...);
&dev->event_lock is HARDIRQ-safe, so interrupts have to be disabled
while grabbing &fasync_struct.fa_lock, otherwise we invert the lock
hierarchy. However, since kill_fasync which calls kill_fasync_rcu is
an exported symbol, it may not necessarily be called with interrupts
disabled.
As kill_fasync_rcu may be called with interrupts disabled (for
example, in the call chain above), we replace calls to
read_lock/read_unlock on &fasync_struct.fa_lock in kill_fasync_rcu
with read_lock_irqsave/read_unlock_irqrestore.
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 8d1ddb5e79374fb277985a6b3faa2ed8631c5b4c upstream.
Syzbot reports a potential deadlock found by the newly added recursive
read deadlock detection in lockdep:
[...] ========================================================
[...] WARNING: possible irq lock inversion dependency detected
[...] 5.9.0-rc2-syzkaller #0 Not tainted
[...] --------------------------------------------------------
[...] syz-executor.1/10214 just changed the state of lock:
[...] ffff88811f506338 (&f->f_owner.lock){.+..}-{2:2}, at: send_sigurg+0x1d/0x200
[...] but this lock was taken by another, HARDIRQ-safe lock in the past:
[...] (&dev->event_lock){-...}-{2:2}
[...]
[...]
[...] and interrupts could create inverse lock ordering between them.
[...]
[...]
[...] other info that might help us debug this:
[...] Chain exists of:
[...] &dev->event_lock --> &new->fa_lock --> &f->f_owner.lock
[...]
[...] Possible interrupt unsafe locking scenario:
[...]
[...] CPU0 CPU1
[...] ---- ----
[...] lock(&f->f_owner.lock);
[...] local_irq_disable();
[...] lock(&dev->event_lock);
[...] lock(&new->fa_lock);
[...] <Interrupt>
[...] lock(&dev->event_lock);
[...]
[...] *** DEADLOCK ***
The corresponding deadlock case is as followed:
CPU 0 CPU 1 CPU 2
read_lock(&fown->lock);
spin_lock_irqsave(&dev->event_lock, ...)
write_lock_irq(&filp->f_owner.lock); // wait for the lock
read_lock(&fown-lock); // have to wait until the writer release
// due to the fairness
<interrupted>
spin_lock_irqsave(&dev->event_lock); // wait for the lock
The lock dependency on CPU 1 happens if there exists a call sequence:
input_inject_event():
spin_lock_irqsave(&dev->event_lock,...);
input_handle_event():
input_pass_values():
input_to_handler():
handler->event(): // evdev_event()
evdev_pass_values():
spin_lock(&client->buffer_lock);
__pass_event():
kill_fasync():
kill_fasync_rcu():
read_lock(&fa->fa_lock);
send_sigio():
read_lock(&fown->lock);
To fix this, make the reader in send_sigurg() and send_sigio() use
read_lock_irqsave() and read_lock_irqrestore().
Reported-by: syzbot+22e87cdf94021b984aa6@syzkaller.appspotmail.com
Reported-by: syzbot+c5e32344981ad9f33750@syzkaller.appspotmail.com
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Variables declared in a switch statement before any case statements
cannot be automatically initialized with compiler instrumentation (as
they are not part of any execution flow). With GCC's proposed automatic
stack variable initialization feature, this triggers a warning (and they
don't get initialized). Clang's automatic stack variable initialization
(via CONFIG_INIT_STACK_ALL=y) doesn't throw a warning, but it also
doesn't initialize such variables[1]. Note that these warnings (or silent
skipping) happen before the dead-store elimination optimization phase,
so even when the automatic initializations are later elided in favor of
direct initializations, the warnings remain.
To avoid these problems, move such variables into the "case" where
they're used or lift them up into the main function body.
fs/fcntl.c: In function ‘send_sigio_to_task’:
fs/fcntl.c:738:20: warning: statement will never be executed [-Wswitch-unreachable]
738 | kernel_siginfo_t si;
| ^~
[1] https://bugs.llvm.org/show_bug.cgi?id=44916
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Pull misc vfs cleanups from Al Viro: "No common topic, just three cleanups". * 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: make __d_alloc() static fs/namespace: add __user to open_tree and move_mount syscalls fs/fnctl: fix missing __user in fcntl_rw_hint()
According to commit message in the original commit c75b1d9421f8 ("fs:
add fcntl() interface for setting/getting write life time hints"),
as well as userspace library[1] and man page update[2], R/W hint constants
are intended to have RWH_* prefix. However, RWF_WRITE_LIFE_NOT_SET retained
"RWF_*" prefix used in the early versions of the proposed patch set[3].
Rename it and provide the old name as a synonym for the new one
for backward compatibility.
[1] https://github.com/axboe/fio/commit/bd553af6c849
[2] https://github.com/mkerrisk/man-pages/commit/580082a186fd
[3] https://www.mail-archive.com/linux-block@vger.kernel.org/msg09638.html
Fixes: c75b1d9421f8 ("fs: add fcntl() interface for setting/getting write life time hints")
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The fcntl_rw_hint() has a missing __user annotation in the code when assinging argp. Add this to fix the following sparse warnings: fs/fcntl.c:280:22: warning: incorrect type in initializer (different address spaces) fs/fcntl.c:280:22: expected unsigned long long [usertype] *argp fs/fcntl.c:280:22: got unsigned long long [noderef] [usertype] <asn:1> * fs/fcntl.c:287:34: warning: incorrect type in argument 1 (different address spaces) fs/fcntl.c:287:34: expected void [noderef] <asn:1> *to fs/fcntl.c:287:34: got unsigned long long [usertype] *argp fs/fcntl.c:291:40: warning: incorrect type in argument 2 (different address spaces) fs/fcntl.c:291:40: expected void const [noderef] <asn:1> *from fs/fcntl.c:291:40: got unsigned long long [usertype] *argp fs/fcntl.c:303:34: warning: incorrect type in argument 1 (different address spaces) fs/fcntl.c:303:34: expected void [noderef] <asn:1> *to fs/fcntl.c:303:34: got unsigned long long [usertype] *argp fs/fcntl.c:307:40: warning: incorrect type in argument 2 (different address spaces) fs/fcntl.c:307:40: expected void const [noderef] <asn:1> *from fs/fcntl.c:307:40: got unsigned long long [usertype] *argp Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>