From: Oleg Nesterov <oleg@redhat.com>
To: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
viro@zeniv.linux.org.uk, arnd@arndb.de, dbueso@suse.de,
axboe@kernel.dk, dave@stgolabs.net, e@80x24.org,
jbaron@akamai.com, linux-fsdevel@vger.kernel.org,
linux-aio@kvack.org, omar.kilani@gmail.com, tglx@linutronix.de,
stable@vger.kernel.org
Subject: Re: [PATCH v2] signal: Adjust error codes according to restore_user_sigmask()
Date: Wed, 22 May 2019 17:05:06 +0200 [thread overview]
Message-ID: <20190522150505.GA4915@redhat.com> (raw)
In-Reply-To: <20190522032144.10995-1-deepa.kernel@gmail.com>
On 05/21, Deepa Dinamani wrote:
>
> Note that this patch returns interrupted errors (EINTR, ERESTARTNOHAND,
> etc) only when there is no other error. If there is a signal and an error
> like EINVAL, the syscalls return -EINVAL rather than the interrupted
> error codes.
Ugh. I need to re-check, but at first glance I really dislike this change.
I think we can fix the problem _and_ simplify the code. Something like below.
The patch is obviously incomplete, it changes only only one caller of
set_user_sigmask(), epoll_pwait() to explain what I mean.
restore_user_sigmask() should simply die. Although perhaps another helper
makes sense to add WARN_ON(test_tsk_restore_sigmask() && !signal_pending).
Oleg.
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 4a0e98d..85f56e4 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -2318,19 +2318,19 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
size_t, sigsetsize)
{
int error;
- sigset_t ksigmask, sigsaved;
/*
* If the caller wants a certain signal mask to be set during the wait,
* we apply it here.
*/
- error = set_user_sigmask(sigmask, &ksigmask, &sigsaved, sigsetsize);
+ error = set_user_sigmask(sigmask, sigsetsize);
if (error)
return error;
error = do_epoll_wait(epfd, events, maxevents, timeout);
- restore_user_sigmask(sigmask, &sigsaved);
+ if (error != -EINTR)
+ restore_saved_sigmask();
return error;
}
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index e412c09..1e82ae0 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -416,7 +416,6 @@ void task_join_group_stop(struct task_struct *task);
static inline void set_restore_sigmask(void)
{
set_thread_flag(TIF_RESTORE_SIGMASK);
- WARN_ON(!test_thread_flag(TIF_SIGPENDING));
}
static inline void clear_tsk_restore_sigmask(struct task_struct *tsk)
@@ -447,7 +446,6 @@ static inline bool test_and_clear_restore_sigmask(void)
static inline void set_restore_sigmask(void)
{
current->restore_sigmask = true;
- WARN_ON(!test_thread_flag(TIF_SIGPENDING));
}
static inline void clear_tsk_restore_sigmask(struct task_struct *tsk)
{
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 9702016..887cea6 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -273,8 +273,7 @@ extern int group_send_sig_info(int sig, struct kernel_siginfo *info,
struct task_struct *p, enum pid_type type);
extern int __group_send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
extern int sigprocmask(int, sigset_t *, sigset_t *);
-extern int set_user_sigmask(const sigset_t __user *usigmask, sigset_t *set,
- sigset_t *oldset, size_t sigsetsize);
+extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
extern void restore_user_sigmask(const void __user *usigmask,
sigset_t *sigsaved);
extern void set_current_blocked(sigset_t *);
diff --git a/kernel/signal.c b/kernel/signal.c
index 227ba17..76f4f9a 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2801,19 +2801,21 @@ EXPORT_SYMBOL(sigprocmask);
* This is useful for syscalls such as ppoll, pselect, io_pgetevents and
* epoll_pwait where a new sigmask is passed from userland for the syscalls.
*/
-int set_user_sigmask(const sigset_t __user *usigmask, sigset_t *set,
- sigset_t *oldset, size_t sigsetsize)
+int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
{
- if (!usigmask)
+ sigset_t *kmask;
+
+ if (!umask)
return 0;
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
- if (copy_from_user(set, usigmask, sizeof(sigset_t)))
+ if (copy_from_user(kmask, umask, sizeof(sigset_t)))
return -EFAULT;
- *oldset = current->blocked;
- set_current_blocked(set);
+ set_restore_sigmask();
+ current->saved_sigmask = current->blocked;
+ set_current_blocked(kmask);
return 0;
}
@@ -2840,39 +2842,6 @@ int set_compat_user_sigmask(const compat_sigset_t __user *usigmask,
EXPORT_SYMBOL(set_compat_user_sigmask);
#endif
-/*
- * restore_user_sigmask:
- * usigmask: sigmask passed in from userland.
- * sigsaved: saved sigmask when the syscall started and changed the sigmask to
- * usigmask.
- *
- * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
- * epoll_pwait where a new sigmask is passed in from userland for the syscalls.
- */
-void restore_user_sigmask(const void __user *usigmask, sigset_t *sigsaved)
-{
-
- if (!usigmask)
- return;
- /*
- * When signals are pending, do not restore them here.
- * Restoring sigmask here can lead to delivering signals that the above
- * syscalls are intended to block because of the sigmask passed in.
- */
- if (signal_pending(current)) {
- current->saved_sigmask = *sigsaved;
- set_restore_sigmask();
- return;
- }
-
- /*
- * This is needed because the fast syscall return path does not restore
- * saved_sigmask when signals are not pending.
- */
- set_current_blocked(sigsaved);
-}
-EXPORT_SYMBOL(restore_user_sigmask);
-
/**
* sys_rt_sigprocmask - change the list of currently blocked signals
* @how: whether to add, remove, or set signals
next prev parent reply other threads:[~2019-05-22 15:05 UTC|newest]
Thread overview: 123+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-22 3:21 [PATCH v2] signal: Adjust error codes according to restore_user_sigmask() Deepa Dinamani
2019-05-22 15:05 ` Oleg Nesterov [this message]
2019-05-22 15:55 ` Deepa Dinamani
2019-05-22 16:14 ` Oleg Nesterov
2019-05-22 16:33 ` Deepa Dinamani
2019-05-23 9:03 ` David Laight
2019-05-23 14:59 ` Oleg Nesterov
2019-05-23 16:18 ` David Laight
2019-05-23 16:36 ` Oleg Nesterov
2019-05-23 16:56 ` David Laight
2019-05-23 18:06 ` Deepa Dinamani
2019-05-23 20:41 ` Deepa Dinamani
2019-05-23 21:06 ` Deepa Dinamani
2019-05-24 9:58 ` David Laight
2019-05-24 14:10 ` Oleg Nesterov
2019-05-24 15:16 ` Deepa Dinamani
2019-05-24 16:33 ` Oleg Nesterov
2019-05-24 17:01 ` Deepa Dinamani
2019-05-27 15:04 ` Oleg Nesterov
2019-05-28 20:47 ` Deepa Dinamani
2019-05-29 16:57 ` Oleg Nesterov
2019-05-29 18:42 ` Deepa Dinamani
2019-05-28 9:02 ` David Laight
2019-05-28 9:12 ` David Laight
2019-05-28 11:37 ` Deepa Dinamani
2019-05-28 12:04 ` David Laight
2019-05-24 14:19 ` Oleg Nesterov
2019-05-24 14:29 ` Deepa Dinamani
2019-05-24 14:51 ` Oleg Nesterov
2019-05-24 13:29 ` Oleg Nesterov
2019-05-24 14:59 ` David Laight
2019-05-24 15:09 ` David Laight
2019-05-24 15:46 ` Oleg Nesterov
2019-05-24 15:44 ` Oleg Nesterov
2019-05-24 16:40 ` David Laight
2019-05-23 14:33 ` Oleg Nesterov
2019-05-22 22:18 ` Chris Down
2019-05-22 22:52 ` Deepa Dinamani
2019-05-29 16:11 ` pselect/etc semantics (Was: [PATCH v2] signal: Adjust error codes according to restore_user_sigmask()) Oleg Nesterov
2019-05-29 16:54 ` David Laight
2019-05-29 18:50 ` Eric Wong
2019-05-30 9:34 ` David Laight
2019-05-30 13:04 ` pselect/etc semantics Eric W. Biederman
2019-05-29 16:56 ` pselect/etc semantics (Was: [PATCH v2] signal: Adjust error codes according to restore_user_sigmask()) Deepa Dinamani
2019-05-29 18:26 ` Deepa Dinamani
2019-05-29 22:32 ` Arnd Bergmann
2019-05-30 1:54 ` pselect/etc semantics Eric W. Biederman
2019-05-30 18:28 ` Arnd Bergmann
2019-05-30 14:40 ` pselect/etc semantics (Was: [PATCH v2] signal: Adjust error codes according to restore_user_sigmask()) Oleg Nesterov
2019-05-30 18:37 ` Arnd Bergmann
2019-05-30 13:01 ` pselect/etc semantics Eric W. Biederman
2019-05-30 15:18 ` David Laight
2019-05-30 16:13 ` Oleg Nesterov
2019-05-30 15:38 ` Eric W. Biederman
2019-05-30 15:48 ` Deepa Dinamani
2019-05-30 16:59 ` Deepa Dinamani
2019-05-30 16:08 ` Oleg Nesterov
2019-05-30 17:20 ` Eric W. Biederman
2019-05-30 16:22 ` David Laight
2019-05-30 15:57 ` Oleg Nesterov
2019-05-30 21:03 ` Eric Wong
2019-06-04 13:41 ` [PATCH] signal: remove the wrong signal_pending() check in restore_user_sigmask() Oleg Nesterov
2019-06-04 15:31 ` Eric W. Biederman
2019-06-04 15:57 ` David Laight
2019-06-04 16:37 ` Arnd Bergmann
2019-06-04 18:14 ` Deepa Dinamani
2019-06-04 18:35 ` Eric Wong
2019-06-04 21:26 ` Linus Torvalds
2019-06-04 22:24 ` Eric Wong
2019-06-04 23:51 ` Eric W. Biederman
2019-06-05 9:04 ` Oleg Nesterov
2019-06-05 8:56 ` Oleg Nesterov
2019-06-05 9:02 ` David Laight
2019-06-05 9:25 ` Oleg Nesterov
2019-06-05 9:58 ` David Laight
2019-06-05 15:58 ` [PATCH -mm 0/1] signal: simplify set_user_sigmask/restore_user_sigmask Oleg Nesterov
2019-06-05 15:58 ` [PATCH -mm 1/1] " Oleg Nesterov
2019-06-06 0:14 ` kbuild test robot
2019-06-06 1:06 ` kbuild test robot
2019-06-06 7:25 ` Oleg Nesterov
2019-06-06 7:30 ` Sedat Dilek
2019-06-05 17:24 ` [PATCH -mm 0/1] " Linus Torvalds
2019-06-06 9:05 ` David Laight
2019-06-06 11:05 ` Oleg Nesterov
2019-06-06 11:29 ` David Laight
2019-06-06 12:41 ` Oleg Nesterov
2019-06-06 13:23 ` David Laight
2019-06-06 10:22 ` Oleg Nesterov
2019-06-06 11:32 ` [PATCH -mm V2 1/1] " Oleg Nesterov
2019-06-06 14:08 ` [PATCH 0/2] select: simplify the usage of restore_saved_sigmask_unless() Oleg Nesterov
2019-06-06 14:08 ` [PATCH 1/2] select: change do_poll() to return -ERESTARTNOHAND rather than -EINTR Oleg Nesterov
2019-06-07 18:05 ` Linus Torvalds
2019-06-06 14:09 ` [PATCH 2/2] select: shift restore_saved_sigmask_unless() into poll_select_copy_remaining() Oleg Nesterov
2019-06-07 21:39 ` [RFC PATCH 0/5]: Removing saved_sigmask Eric W. Biederman
2019-06-07 21:41 ` [RFC PATCH 1/5] signal: Teach sigsuspend to use set_user_sigmask Eric W. Biederman
2019-06-07 22:07 ` Linus Torvalds
2019-06-10 16:22 ` Oleg Nesterov
2019-06-10 21:20 ` Eric W. Biederman
2019-06-11 9:52 ` David Laight
2019-06-11 11:14 ` David Laight
2019-06-12 12:55 ` Eric W. Biederman
2019-06-12 13:24 ` David Laight
2019-06-12 13:35 ` Oleg Nesterov
2019-06-12 13:39 ` David Laight
2019-06-11 15:46 ` David Laight
2019-06-12 12:40 ` Eric W. Biederman
2019-06-12 13:45 ` Oleg Nesterov
2019-06-12 14:18 ` David Laight
2019-06-12 15:11 ` Eric W. Biederman
2019-06-12 15:37 ` Oleg Nesterov
2019-06-13 8:48 ` David Laight
2019-06-13 9:43 ` Oleg Nesterov
2019-06-13 10:56 ` David Laight
2019-06-13 12:43 ` Oleg Nesterov
2019-06-11 18:55 ` Oleg Nesterov
2019-06-11 19:02 ` Eric W. Biederman
2019-06-12 8:39 ` David Laight
2019-06-12 13:09 ` Eric W. Biederman
2019-06-07 21:41 ` [RFC PATCH 2/5] signal/kvm: Stop using sigprocmask in kvm_sigset_(activate|deactivate) Eric W. Biederman
2019-06-07 21:42 ` [RFC PATCH 3/5] signal: Always keep real_blocked in sync with blocked Eric W. Biederman
2019-06-07 21:43 ` [RFC PATCH 4/5] signal: Remove saved_sigmask Eric W. Biederman
2019-06-07 21:44 ` [RFC PATCH 5/5] signal: Remove the unnecessary restore_sigmask flag Eric W. Biederman
2019-06-11 18:58 ` [RFC PATCH 0/5]: Removing saved_sigmask Oleg Nesterov
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