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authorAndrei Vagin <avagin@gmail.com>2019-03-29 06:44:13 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-29 20:01:37 +0300
commitfcfc2aa0185f4a731d05a21e9f359968fdfd02e7 (patch)
treebe2e72904e527207f223eeb070b94062999ebdbf
parenteebf36480678f948b3ed15d56ca7b8e6194e7c18 (diff)
downloadlinux-fcfc2aa0185f4a731d05a21e9f359968fdfd02e7.tar.xz
ptrace: take into account saved_sigmask in PTRACE{GET,SET}SIGMASK
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_GETSIGMASK returns saved_sigmask if 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> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/sched/signal.h18
-rw-r--r--kernel/ptrace.c15
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;
}