Messages in this thread Patch in this message | | | From | Andrey Vagin <> | Subject | [PATCH] ptrace: add ability to get/set signal-blocked mask | Date | Mon, 22 Apr 2013 13:53:20 +0400 |
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crtools uses a parasite code for dumping processes. The parasite code is injected into a process with help PTRACE_SEIZE.
Currently crtools blocks signals from a parasite code. If a process has pending signals, crtools wait while a process handles these signals.
This method is not suitable for stopped tasks. A stopped task can have a few pending signals, when we will try to execute a parasite code, we will need to drop SIGSTOP, but all other signals must remain pending, because a state of processes must not be changed during checkpointing.
This patch adds two ptrace commands to set/get signal-blocked mask.
I think gdb can use this commands too.
Cc: Roland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Signed-off-by: Andrey Vagin <avagin@openvz.org> --- include/linux/signal.h | 1 + include/uapi/linux/ptrace.h | 2 ++ kernel/ptrace.c | 36 ++++++++++++++++++++++++++++++++++++ kernel/signal.c | 2 +- 4 files changed, 40 insertions(+), 1 deletion(-)
diff --git a/include/linux/signal.h b/include/linux/signal.h index a2dcb94..706b88d 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -246,6 +246,7 @@ extern int do_sigtimedwait(const sigset_t *, siginfo_t *, extern int sigprocmask(int, sigset_t *, sigset_t *); extern void set_current_blocked(sigset_t *); extern void __set_current_blocked(const sigset_t *); +extern void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset); extern int show_unhandled_signals; extern int sigsuspend(sigset_t *); diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h index 52ebcc8..1527684 100644 --- a/include/uapi/linux/ptrace.h +++ b/include/uapi/linux/ptrace.h @@ -54,6 +54,8 @@ #define PTRACE_LISTEN 0x4208 #define PTRACE_PEEKSIGINFO 0x4209 +#define PTRACE_GETSIGMASK 0x420a +#define PTRACE_SETSIGMASK 0x420b struct ptrace_peeksiginfo_args { __u64 off; /* from which siginfo to start */ diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 17ae54d..317a737 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -841,6 +841,42 @@ int ptrace_request(struct task_struct *child, long request, ret = ptrace_setsiginfo(child, &siginfo); break; + case PTRACE_GETSIGMASK: + if (addr != sizeof(sigset_t)) { + ret = -EINVAL; + break; + } + + if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t))) + ret = -EFAULT; + else + ret = 0; + + break; + + case PTRACE_SETSIGMASK: + { + sigset_t new_set; + + if (addr != sizeof(sigset_t)) { + ret = -EINVAL; + break; + } + + if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) { + ret = -EFAULT; + break; + } + + sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); + + spin_lock_irq(&child->sighand->siglock); + __set_task_blocked(child, &new_set); + spin_unlock_irq(&child->sighand->siglock); + + ret = 0; + break; + } case PTRACE_INTERRUPT: /* * Stop tracee without any side-effect on signal or job diff --git a/kernel/signal.c b/kernel/signal.c index dd72567..d757e5b 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2522,7 +2522,7 @@ long do_no_restart_syscall(struct restart_block *param) return -EINTR; } -static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset) +void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset) { if (signal_pending(tsk) && !thread_group_empty(tsk)) { sigset_t newblocked; -- 1.8.1.4
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