From: Guillermo <gdiazhartusch@gmail.com>
To: supervision <supervision@list.skarnet.org>
Subject: Re: runit SIGPWR support
Date: Tue, 25 Feb 2020 15:38:15 -0300 [thread overview]
Message-ID: <CADQ2Nw9hu0tt2_XkF2-3D9z2d0JyAah0Eog=YkXxBMLtCAru7w@mail.gmail.com> (raw)
In-Reply-To: <00e1ad14-3bd4-c9ec-8f18-a33a1ba37bb6@NTLWorld.COM>
El mar., 25 feb. 2020 a las 6:08, Jonathan de Boyne Pollard escribió:
>
> Laurent Bercot:
> > Of course, but once the fd is closed, /dev/console should not have
> > any impact on the process, so would a kbrequest still reach it?
>
> Yes.
Also, I tested it :) I added an open2("/dev/tty0", O_RDONLY |
O_NOCTTY) + ioctl() + fd_close() sequence to s6-linux-init.c right
after the reboot(RB_DISABLE_CAD) call, specifying SIGQUIT as the
argument of the KDSIGACCEPT ioctl (to use a signal 'divertable' by
s6-2.9.0.1's s6-svscan), and the SIGQUIT handler does get called
indeed when I press Alt + Up Arrow.
The file descriptor specified in the ioctl() call, as far as I can
tell, is only used by the kernel to check permissions. The ioctl is
allowed if the FD corresponds to the process' control terminal, or if
the process has CAP_KILL or CAP_SYS_TTY_CONFIG capabilities. But the
kernel just seems to record the PID of the invoking process and the
requested signal number. (vt_ioctl() in drivers/tty/vt/vt_ioctl.c).
> First: This is a kernel virtual terminal thing not a console
> thing. Strictly speaking, it is doing it wrongly to access it through
> the console device, which is not necessarily a KVT.
Yeah, I overlooked this. I suppose it'll work on /dev/console as long
as it is a kernel virtual terminal, but it won't always be the case.
sysvinit and systemd use /dev/tty0 for the ioctl (and sysvinit falls
back to its standard input if that fails), so I used that for the
(second) test.
G.
next prev parent reply other threads:[~2020-02-25 18:38 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1beb6e35-d4be-60b8-fc52-af666c4fffe3@gmx.com>
2020-02-12 14:25 ` innerspacepilot
2020-02-12 21:54 ` Colin Booth
2020-02-12 22:16 ` Dewayne Geraghty
2020-02-14 9:38 ` Jeff
2020-02-14 12:38 ` Steve Litt
2020-02-15 10:47 ` fungal-net
2020-02-14 10:08 ` Jeff
2020-02-14 10:46 ` Jeff
2020-02-14 12:29 ` innerspacepilot
2020-02-14 12:45 ` Steve Litt
[not found] ` <CALZWFRLvtofWfP4kzxJ8_8_K3nzebPjCR-NsJ2MU22cSuaOLng@mail.gmail.com>
[not found] ` <20200214182241.15614126@mydesk.domain.cxm>
2020-02-17 19:46 ` Cameron Nemo
2020-02-23 16:11 ` Jeff
2020-02-17 14:39 ` Jeff
2020-02-14 14:02 ` Casper Ti. Vector
2020-02-17 14:45 ` Jeff
2020-02-17 14:50 ` Jeff
2020-02-14 13:15 ` Casper Ti. Vector
2020-02-14 13:39 ` innerspacepilot
2020-02-14 13:57 ` Casper Ti. Vector
2020-02-14 14:06 ` innerspacepilot
2020-02-14 14:25 ` Casper Ti. Vector
2020-02-14 18:30 ` Laurent Bercot
2020-02-17 10:00 ` innerspacepilot
2020-02-17 15:13 ` Jeff
2020-02-18 9:39 ` Laurent Bercot
2020-02-20 20:39 ` Serge E. Hallyn
2020-02-23 16:51 ` Jeff
2020-02-23 23:53 ` Laurent Bercot
2020-02-24 6:31 ` innerspacepilot
2020-02-24 10:23 ` Laurent Bercot
2020-02-24 13:00 ` Jeff
2020-02-24 19:53 ` Laurent Bercot
2020-02-24 13:12 ` innerspacepilot
2020-02-24 15:26 ` Serge E. Hallyn
2020-02-26 8:07 ` innerspacepilot
2020-02-28 6:39 ` Jan Braun
2020-02-28 9:45 ` Alex Suykov
2020-02-28 23:50 ` fungal-net
2020-02-29 13:44 ` Jonathan de Boyne Pollard
2020-02-29 18:20 ` Guillermo
2020-03-06 20:07 ` innerspacepilot
2020-03-06 20:09 ` innerspacepilot
2020-02-25 8:39 ` Jonathan de Boyne Pollard
2020-02-24 21:13 ` Guillermo
2020-02-24 22:25 ` Laurent Bercot
2020-02-24 22:49 ` Laurent Bercot
2020-02-24 23:08 ` Guillermo
2020-02-25 1:48 ` Laurent Bercot
2020-02-25 9:08 ` Jonathan de Boyne Pollard
2020-02-25 18:38 ` Guillermo [this message]
2020-03-16 12:49 ` Jeff
2020-03-16 17:13 ` Jeff
2020-02-24 23:03 ` Guillermo
2020-03-16 12:31 ` Jeff
2020-03-16 18:03 ` Laurent Bercot
2020-02-23 17:31 ` Jeff
2020-02-24 0:33 ` Laurent Bercot
2020-02-14 19:08 ` John W Higgins
2020-02-14 23:18 ` Laurent Bercot
2020-02-14 23:38 ` John W Higgins
2020-02-15 2:15 ` Laurent Bercot
2020-04-14 16:57 Maxim Vetsalo
-- strict thread matches above, loose matches on Subject: below --
2020-01-23 20:44 innerspacepilot
2020-01-31 4:39 ` Colin Booth
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