From: Andrei Vagin <avagin@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>
Cc: linux-kernel@vger.kernel.org, Andrei Vagin <avagin@gmail.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Stephen Rothwell <sfr@canb.auug.org.au>
Subject: [RESEND PATCH] ptrace: take into account saved_sigmask in PTRACE_{GET,SET}SIGMASK
Date: Tue, 19 Mar 2019 12:19:57 -0700 [thread overview]
Message-ID: <20190319191957.27156-1-avagin@gmail.com> (raw)
There are a few system calls (pselect, ppoll, etc) which replace a task
sigmask while they are running in a kernel-space
When a task calls one of these syscalls, the kernel saves a current
sigmask in task->saved_sigmask and sets a syscall sigmask.
On syscall-exit-stop, ptrace traps a task before restoring the
saved_sigmask, so PTRACE_GETSIGMASK returns the syscall sigmask and
PTRACE_SETSIGMASK does nothing, because its sigmask is replaced by
saved_sigmask, when the task returns to user-space.
This patch fixes this problem. PTRACE_GET_SIGMASK returns saved_sigmask
is it's set. PTRACE_SETSIGMASK drops the TIF_RESTORE_SIGMASK flag.
Link: http://lkml.kernel.org/r/20181120060616.6043-1-avagin@gmail.com
Fixes: 29000caecbe8 ("ptrace: add ability to get/set signal-blocked mask")
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
Hello Andrew,
This patch is in a queue for a long time and it looks like you are
waiting ack from Oleg. He said the patch is fine:
https://www.spinics.net/lists/kernel/msg2972154.html
And promised to send a formal ack in reply to this email.
include/linux/sched/signal.h | 18 ++++++++++++++++++
kernel/ptrace.c | 15 +++++++++++++--
2 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index ae5655197698..e412c092c1e8 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -418,10 +418,20 @@ 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)
+{
+ clear_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK);
+}
+
static inline void clear_restore_sigmask(void)
{
clear_thread_flag(TIF_RESTORE_SIGMASK);
}
+static inline bool test_tsk_restore_sigmask(struct task_struct *tsk)
+{
+ return test_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK);
+}
static inline bool test_restore_sigmask(void)
{
return test_thread_flag(TIF_RESTORE_SIGMASK);
@@ -439,6 +449,10 @@ 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)
+{
+ tsk->restore_sigmask = false;
+}
static inline void clear_restore_sigmask(void)
{
current->restore_sigmask = false;
@@ -447,6 +461,10 @@ static inline bool test_restore_sigmask(void)
{
return current->restore_sigmask;
}
+static inline bool test_tsk_restore_sigmask(struct task_struct *tsk)
+{
+ return tsk->restore_sigmask;
+}
static inline bool test_and_clear_restore_sigmask(void)
{
if (!current->restore_sigmask)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 771e93f9c43f..6f357f4fc859 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -29,6 +29,7 @@
#include <linux/hw_breakpoint.h>
#include <linux/cn_proc.h>
#include <linux/compat.h>
+#include <linux/sched/signal.h>
/*
* Access another process' address space via ptrace.
@@ -924,18 +925,26 @@ int ptrace_request(struct task_struct *child, long request,
ret = ptrace_setsiginfo(child, &siginfo);
break;
- case PTRACE_GETSIGMASK:
+ case PTRACE_GETSIGMASK: {
+ sigset_t *mask;
+
if (addr != sizeof(sigset_t)) {
ret = -EINVAL;
break;
}
- if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))
+ if (test_tsk_restore_sigmask(child))
+ mask = &child->saved_sigmask;
+ else
+ mask = &child->blocked;
+
+ if (copy_to_user(datavp, mask, sizeof(sigset_t)))
ret = -EFAULT;
else
ret = 0;
break;
+ }
case PTRACE_SETSIGMASK: {
sigset_t new_set;
@@ -961,6 +970,8 @@ int ptrace_request(struct task_struct *child, long request,
child->blocked = new_set;
spin_unlock_irq(&child->sighand->siglock);
+ clear_tsk_restore_sigmask(child);
+
ret = 0;
break;
}
--
2.20.1
next reply other threads:[~2019-03-19 19:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-19 19:19 Andrei Vagin [this message]
2019-03-19 22:32 ` [RESEND PATCH] ptrace: take into account saved_sigmask in PTRACE_{GET,SET}SIGMASK Dmitry V. Levin
2019-03-19 22:58 ` Andrew Morton
2019-03-20 13:27 ` Oleg Nesterov
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