From 9380ec351387cc78240b975c45bd1f39aa6a9e65 Mon Sep 17 00:00:00 2001 From: Andrey Vagin Date: Fri, 28 Jun 2013 09:53:49 +1000 Subject: [PATCH] ptrace: add ability to get/set signal-blocked mask 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. Signed-off-by: Andrey Vagin Reviewed-by: Oleg Nesterov Cc: Roland McGrath Cc: Michael Kerrisk Cc: Pavel Emelyanov Cc: Cyrill Gorcunov Signed-off-by: Andrew Morton --- include/uapi/linux/ptrace.h | 3 +++ kernel/ptrace.c | 42 +++++++++++++++++++++++++++++++++++++ 2 files changed, 45 insertions(+) diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h index 52ebcc89f306..cf1019e15f5b 100644 --- a/include/uapi/linux/ptrace.h +++ b/include/uapi/linux/ptrace.h @@ -61,6 +61,9 @@ struct ptrace_peeksiginfo_args { __s32 nr; /* how may siginfos to take */ }; +#define PTRACE_GETSIGMASK 0x420a +#define PTRACE_SETSIGMASK 0x420b + /* Read signals from a shared (process wide) queue */ #define PTRACE_PEEKSIGINFO_SHARED (1 << 0) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 0ea7f225ba95..565a7d1d9726 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -843,6 +843,48 @@ 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)); + + /* + * Every thread does recalc_sigpending() after resume, so + * retarget_shared_pending() and recalc_sigpending() are not + * called here. + */ + spin_lock_irq(&child->sighand->siglock); + child->blocked = new_set; + spin_unlock_irq(&child->sighand->siglock); + + ret = 0; + break; + } + case PTRACE_INTERRUPT: /* * Stop tracee without any side-effect on signal or job -- 2.39.5