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: 29000caecb
("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>
This commit is contained in:
parent
eebf364806
commit
fcfc2aa018
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@ -418,10 +418,20 @@ static inline void set_restore_sigmask(void)
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set_thread_flag(TIF_RESTORE_SIGMASK);
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WARN_ON(!test_thread_flag(TIF_SIGPENDING));
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}
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static inline void clear_tsk_restore_sigmask(struct task_struct *tsk)
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{
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clear_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK);
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}
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static inline void clear_restore_sigmask(void)
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{
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clear_thread_flag(TIF_RESTORE_SIGMASK);
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}
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static inline bool test_tsk_restore_sigmask(struct task_struct *tsk)
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{
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return test_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK);
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}
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static inline bool test_restore_sigmask(void)
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{
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return test_thread_flag(TIF_RESTORE_SIGMASK);
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@ -439,6 +449,10 @@ static inline void set_restore_sigmask(void)
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current->restore_sigmask = true;
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WARN_ON(!test_thread_flag(TIF_SIGPENDING));
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}
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static inline void clear_tsk_restore_sigmask(struct task_struct *tsk)
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{
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tsk->restore_sigmask = false;
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}
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static inline void clear_restore_sigmask(void)
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{
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current->restore_sigmask = false;
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@ -447,6 +461,10 @@ static inline bool test_restore_sigmask(void)
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{
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return current->restore_sigmask;
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}
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static inline bool test_tsk_restore_sigmask(struct task_struct *tsk)
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{
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return tsk->restore_sigmask;
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}
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static inline bool test_and_clear_restore_sigmask(void)
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{
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if (!current->restore_sigmask)
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@ -29,6 +29,7 @@
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#include <linux/hw_breakpoint.h>
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#include <linux/cn_proc.h>
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#include <linux/compat.h>
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#include <linux/sched/signal.h>
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/*
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* Access another process' address space via ptrace.
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@ -924,18 +925,26 @@ int ptrace_request(struct task_struct *child, long request,
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ret = ptrace_setsiginfo(child, &siginfo);
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break;
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case PTRACE_GETSIGMASK:
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case PTRACE_GETSIGMASK: {
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sigset_t *mask;
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if (addr != sizeof(sigset_t)) {
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ret = -EINVAL;
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break;
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}
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if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))
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if (test_tsk_restore_sigmask(child))
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mask = &child->saved_sigmask;
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else
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mask = &child->blocked;
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if (copy_to_user(datavp, mask, sizeof(sigset_t)))
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ret = -EFAULT;
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else
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ret = 0;
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break;
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}
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case PTRACE_SETSIGMASK: {
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sigset_t new_set;
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@ -961,6 +970,8 @@ int ptrace_request(struct task_struct *child, long request,
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child->blocked = new_set;
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spin_unlock_irq(&child->sighand->siglock);
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clear_tsk_restore_sigmask(child);
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ret = 0;
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break;
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}
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