Re: SIGNAL_UNKILLABLE and init again
Hi Jamie, On 08/14, Jamie Iles wrote: > > > > Not sure, let me think a bit more... and this is not enough anyway. > > > > > > perhaps we should start with this simple change, but the "real" fix > > > needs a lot of cleanups, although I am not sure if we will ever do this. > > > > Okay, sounds good. I'm happy to spend more time looking at this if you > > have suggestions - in the context of namespaces and containers this > > seems more relevant than when it was just the system init that we were > > protecting. > > Any objections to moving ahead with this patch? Oh, sorry. OK, lets do this simple change then try to improve this logic further. I'm afraid you need to re-send your patch, sorry. Oleg.
Re: SIGNAL_UNKILLABLE and init again
Hi Jamie, On 08/14, Jamie Iles wrote: > > > > Not sure, let me think a bit more... and this is not enough anyway. > > > > > > perhaps we should start with this simple change, but the "real" fix > > > needs a lot of cleanups, although I am not sure if we will ever do this. > > > > Okay, sounds good. I'm happy to spend more time looking at this if you > > have suggestions - in the context of namespaces and containers this > > seems more relevant than when it was just the system init that we were > > protecting. > > Any objections to moving ahead with this patch? Oh, sorry. OK, lets do this simple change then try to improve this logic further. I'm afraid you need to re-send your patch, sorry. Oleg.
Re: SIGNAL_UNKILLABLE and init again
Hi Oleg, On Thu, Apr 27, 2017 at 01:16:51PM +0100, Jamie Iles wrote: > On Wed, Apr 26, 2017 at 05:18:58PM +0200, Oleg Nesterov wrote: > > Hi Jamie, > > > > On 04/25, Jamie Iles wrote: > > > > > > Hi Oleg, > > > > > > I'm back looking at SIGNAL_UNKILLABLE and debugging child reapers again, > > > and the current issue is when running code in the target process, > > > SIGTRAP firing and that causing SIGNAL_UNKILLABLE protection to be > > > removed in force_sig_info(): > > > > > > if (action->sa.sa_handler == SIG_DFL) > > > t->signal->flags &= ~SIGNAL_UNKILLABLE; > > > > Yes, this is what I meant when I said force_sig_info() needs changes too. > > I was going to fix it "tomorrow" but I was distracted and then forgot. > > > > > @@ -1185,7 +1185,7 @@ force_sig_info(int sig, struct siginfo *info, > > > struct task_struct *t) > > > recalc_sigpending_and_wake(t); > > > } > > > } > > > - if (action->sa.sa_handler == SIG_DFL) > > > + if (action->sa.sa_handler == SIG_DFL && !t->ptrace) > > > t->signal->flags &= ~SIGNAL_UNKILLABLE; > > > ret = specific_send_sig_info(sig, info, t); > > > spin_unlock_irqrestore(>sighand->siglock, flags); > > > > Not sure, let me think a bit more... and this is not enough anyway. > > > > perhaps we should start with this simple change, but the "real" fix > > needs a lot of cleanups, although I am not sure if we will ever do this. > > Okay, sounds good. I'm happy to spend more time looking at this if you > have suggestions - in the context of namespaces and containers this > seems more relevant than when it was just the system init that we were > protecting. Any objections to moving ahead with this patch? Thanks, Jamie
Re: SIGNAL_UNKILLABLE and init again
Hi Oleg, On Thu, Apr 27, 2017 at 01:16:51PM +0100, Jamie Iles wrote: > On Wed, Apr 26, 2017 at 05:18:58PM +0200, Oleg Nesterov wrote: > > Hi Jamie, > > > > On 04/25, Jamie Iles wrote: > > > > > > Hi Oleg, > > > > > > I'm back looking at SIGNAL_UNKILLABLE and debugging child reapers again, > > > and the current issue is when running code in the target process, > > > SIGTRAP firing and that causing SIGNAL_UNKILLABLE protection to be > > > removed in force_sig_info(): > > > > > > if (action->sa.sa_handler == SIG_DFL) > > > t->signal->flags &= ~SIGNAL_UNKILLABLE; > > > > Yes, this is what I meant when I said force_sig_info() needs changes too. > > I was going to fix it "tomorrow" but I was distracted and then forgot. > > > > > @@ -1185,7 +1185,7 @@ force_sig_info(int sig, struct siginfo *info, > > > struct task_struct *t) > > > recalc_sigpending_and_wake(t); > > > } > > > } > > > - if (action->sa.sa_handler == SIG_DFL) > > > + if (action->sa.sa_handler == SIG_DFL && !t->ptrace) > > > t->signal->flags &= ~SIGNAL_UNKILLABLE; > > > ret = specific_send_sig_info(sig, info, t); > > > spin_unlock_irqrestore(>sighand->siglock, flags); > > > > Not sure, let me think a bit more... and this is not enough anyway. > > > > perhaps we should start with this simple change, but the "real" fix > > needs a lot of cleanups, although I am not sure if we will ever do this. > > Okay, sounds good. I'm happy to spend more time looking at this if you > have suggestions - in the context of namespaces and containers this > seems more relevant than when it was just the system init that we were > protecting. Any objections to moving ahead with this patch? Thanks, Jamie
Re: SIGNAL_UNKILLABLE and init again
On Wed, Apr 26, 2017 at 05:18:58PM +0200, Oleg Nesterov wrote: > Hi Jamie, > > On 04/25, Jamie Iles wrote: > > > > Hi Oleg, > > > > I'm back looking at SIGNAL_UNKILLABLE and debugging child reapers again, > > and the current issue is when running code in the target process, > > SIGTRAP firing and that causing SIGNAL_UNKILLABLE protection to be > > removed in force_sig_info(): > > > > if (action->sa.sa_handler == SIG_DFL) > > t->signal->flags &= ~SIGNAL_UNKILLABLE; > > Yes, this is what I meant when I said force_sig_info() needs changes too. > I was going to fix it "tomorrow" but I was distracted and then forgot. > > > @@ -1185,7 +1185,7 @@ force_sig_info(int sig, struct siginfo *info, > > struct task_struct *t) > > recalc_sigpending_and_wake(t); > > } > > } > > - if (action->sa.sa_handler == SIG_DFL) > > + if (action->sa.sa_handler == SIG_DFL && !t->ptrace) > > t->signal->flags &= ~SIGNAL_UNKILLABLE; > > ret = specific_send_sig_info(sig, info, t); > > spin_unlock_irqrestore(>sighand->siglock, flags); > > Not sure, let me think a bit more... and this is not enough anyway. > > perhaps we should start with this simple change, but the "real" fix > needs a lot of cleanups, although I am not sure if we will ever do this. Okay, sounds good. I'm happy to spend more time looking at this if you have suggestions - in the context of namespaces and containers this seems more relevant than when it was just the system init that we were protecting. Jamie
Re: SIGNAL_UNKILLABLE and init again
On Wed, Apr 26, 2017 at 05:18:58PM +0200, Oleg Nesterov wrote: > Hi Jamie, > > On 04/25, Jamie Iles wrote: > > > > Hi Oleg, > > > > I'm back looking at SIGNAL_UNKILLABLE and debugging child reapers again, > > and the current issue is when running code in the target process, > > SIGTRAP firing and that causing SIGNAL_UNKILLABLE protection to be > > removed in force_sig_info(): > > > > if (action->sa.sa_handler == SIG_DFL) > > t->signal->flags &= ~SIGNAL_UNKILLABLE; > > Yes, this is what I meant when I said force_sig_info() needs changes too. > I was going to fix it "tomorrow" but I was distracted and then forgot. > > > @@ -1185,7 +1185,7 @@ force_sig_info(int sig, struct siginfo *info, > > struct task_struct *t) > > recalc_sigpending_and_wake(t); > > } > > } > > - if (action->sa.sa_handler == SIG_DFL) > > + if (action->sa.sa_handler == SIG_DFL && !t->ptrace) > > t->signal->flags &= ~SIGNAL_UNKILLABLE; > > ret = specific_send_sig_info(sig, info, t); > > spin_unlock_irqrestore(>sighand->siglock, flags); > > Not sure, let me think a bit more... and this is not enough anyway. > > perhaps we should start with this simple change, but the "real" fix > needs a lot of cleanups, although I am not sure if we will ever do this. Okay, sounds good. I'm happy to spend more time looking at this if you have suggestions - in the context of namespaces and containers this seems more relevant than when it was just the system init that we were protecting. Jamie
Re: SIGNAL_UNKILLABLE and init again
Hi Jamie, On 04/25, Jamie Iles wrote: > > Hi Oleg, > > I'm back looking at SIGNAL_UNKILLABLE and debugging child reapers again, > and the current issue is when running code in the target process, > SIGTRAP firing and that causing SIGNAL_UNKILLABLE protection to be > removed in force_sig_info(): > > if (action->sa.sa_handler == SIG_DFL) > t->signal->flags &= ~SIGNAL_UNKILLABLE; Yes, this is what I meant when I said force_sig_info() needs changes too. I was going to fix it "tomorrow" but I was distracted and then forgot. > @@ -1185,7 +1185,7 @@ force_sig_info(int sig, struct siginfo *info, struct > task_struct *t) > recalc_sigpending_and_wake(t); > } > } > - if (action->sa.sa_handler == SIG_DFL) > + if (action->sa.sa_handler == SIG_DFL && !t->ptrace) > t->signal->flags &= ~SIGNAL_UNKILLABLE; > ret = specific_send_sig_info(sig, info, t); > spin_unlock_irqrestore(>sighand->siglock, flags); Not sure, let me think a bit more... and this is not enough anyway. perhaps we should start with this simple change, but the "real" fix needs a lot of cleanups, although I am not sure if we will ever do this. Oleg.
Re: SIGNAL_UNKILLABLE and init again
Hi Jamie, On 04/25, Jamie Iles wrote: > > Hi Oleg, > > I'm back looking at SIGNAL_UNKILLABLE and debugging child reapers again, > and the current issue is when running code in the target process, > SIGTRAP firing and that causing SIGNAL_UNKILLABLE protection to be > removed in force_sig_info(): > > if (action->sa.sa_handler == SIG_DFL) > t->signal->flags &= ~SIGNAL_UNKILLABLE; Yes, this is what I meant when I said force_sig_info() needs changes too. I was going to fix it "tomorrow" but I was distracted and then forgot. > @@ -1185,7 +1185,7 @@ force_sig_info(int sig, struct siginfo *info, struct > task_struct *t) > recalc_sigpending_and_wake(t); > } > } > - if (action->sa.sa_handler == SIG_DFL) > + if (action->sa.sa_handler == SIG_DFL && !t->ptrace) > t->signal->flags &= ~SIGNAL_UNKILLABLE; > ret = specific_send_sig_info(sig, info, t); > spin_unlock_irqrestore(>sighand->siglock, flags); Not sure, let me think a bit more... and this is not enough anyway. perhaps we should start with this simple change, but the "real" fix needs a lot of cleanups, although I am not sure if we will ever do this. Oleg.
SIGNAL_UNKILLABLE and init again
Hi Oleg, I'm back looking at SIGNAL_UNKILLABLE and debugging child reapers again, and the current issue is when running code in the target process, SIGTRAP firing and that causing SIGNAL_UNKILLABLE protection to be removed in force_sig_info(): if (action->sa.sa_handler == SIG_DFL) t->signal->flags &= ~SIGNAL_UNKILLABLE; Would relaxing that if the task is being traced with something like diff --git i/kernel/signal.c w/kernel/signal.c index 7e59ebc2c25e..f701f1889895 100644 --- i/kernel/signal.c +++ w/kernel/signal.c @@ -1185,7 +1185,7 @@ force_sig_info(int sig, struct siginfo *info, struct task_struct *t) recalc_sigpending_and_wake(t); } } - if (action->sa.sa_handler == SIG_DFL) + if (action->sa.sa_handler == SIG_DFL && !t->ptrace) t->signal->flags &= ~SIGNAL_UNKILLABLE; ret = specific_send_sig_info(sig, info, t); spin_unlock_irqrestore(>sighand->siglock, flags); make any sense? It does address the issue that I'm seeing, but are there any downsides to doing so? Thanks, Jamie
SIGNAL_UNKILLABLE and init again
Hi Oleg, I'm back looking at SIGNAL_UNKILLABLE and debugging child reapers again, and the current issue is when running code in the target process, SIGTRAP firing and that causing SIGNAL_UNKILLABLE protection to be removed in force_sig_info(): if (action->sa.sa_handler == SIG_DFL) t->signal->flags &= ~SIGNAL_UNKILLABLE; Would relaxing that if the task is being traced with something like diff --git i/kernel/signal.c w/kernel/signal.c index 7e59ebc2c25e..f701f1889895 100644 --- i/kernel/signal.c +++ w/kernel/signal.c @@ -1185,7 +1185,7 @@ force_sig_info(int sig, struct siginfo *info, struct task_struct *t) recalc_sigpending_and_wake(t); } } - if (action->sa.sa_handler == SIG_DFL) + if (action->sa.sa_handler == SIG_DFL && !t->ptrace) t->signal->flags &= ~SIGNAL_UNKILLABLE; ret = specific_send_sig_info(sig, info, t); spin_unlock_irqrestore(>sighand->siglock, flags); make any sense? It does address the issue that I'm seeing, but are there any downsides to doing so? Thanks, Jamie
