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Groups > linux.debian.user > #162614
| From | Gary Dale <garydale@torfree.net> |
|---|---|
| Newsgroups | linux.debian.user |
| Subject | Re: Prevent shutdown with systemctl |
| Date | 2016-01-04 22:50 +0100 |
| Message-ID | <qNlaP-Er-23@gated-at.bofh.it> (permalink) |
| References | <qNfI7-5oL-11@gated-at.bofh.it> <qNgXw-6p8-19@gated-at.bofh.it> <qNhqx-6E0-1@gated-at.bofh.it> <qNjVp-8lm-23@gated-at.bofh.it> <qNkHM-sc-9@gated-at.bofh.it> |
| Organization | eXtreme Ground |
On 04/01/16 03:39 PM, tomas@tuxteam.de wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On Mon, Jan 04, 2016 at 03:25:02PM -0500, Gary Dale wrote: >> On 04/01/16 12:14 PM, tomas@tuxteam.de wrote: > [...] > >>> Dunno about systemctl, but FWIW you can't change the permissions of >>> a symlink. It's always "all on". >>> >>> >> Interesting. Why do they behave that way? Hard links don't (but >> replacing the symlink with a hardlink would fail if /bin & /sbin >> were on different devices. Also, I gather that systemctl looks at >> how it is called to determine the action it needs to take - would >> that create a problem if called from a hard link instead of a >> symlink?). > Perhaps I was a bit cavalier with my "all on": applications *doing* something > useful with a symlink reference it (except things like "rm", of course). > > Thus, the permissions of the referenced-to file apply. Otherwise -- > imagine: I do an ln -s /bin/bash $HOME, chmod u+w $HOME/bas > (since I own the link) and now have write access to the system shell?! > > Hard links are a completely different kind of animal: they are > alternative directory entries for the same blob of data. Consequently, > there is no "primary" (as there is in symlinks). There are no > dangling hardlinks (unless your file system is corrupted). > As you can well imagine, some restrictions apply in the creation > of hardlinks: > > tomas@rasputin:~$ sudo useradd -m test > [sudo] password for tomas: > tomas@rasputin:~$ ls -al /home/test > total 20 > drwxr-xr-x 2 test test 4096 Jan 4 21:50 . > drwxr-xr-x 9 root root 4096 Jan 4 21:50 .. > -rw-r--r-- 1 test test 220 Apr 10 2010 .bash_logout > -rw-r--r-- 1 test test 3392 Jul 13 2012 .bashrc > -rw-r--r-- 1 test test 675 Apr 10 2010 .profile > tomas@rasputin:~$ ln /home/test/.profile test-profile > ln: failed to create hard link `test-profile' => `/home/test/.profile': Operation not permitted > > Regards > - -- tomás Actually I don't see it that way at all. The symlink example is no different from the hardlink case in that I can create a hardlink that has different permissions than the original file. Indeed I can execute systemctl as a normal user by creating a hardlink to it. If that is a problem with symlinks, shouldn't it also be with hardlinks?
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Prevent shutdown with systemctl Floris <jkfloris@dds.nl> - 2016-01-04 17:00 +0100
Re: Prevent shutdown with systemctl Michael Biebl <biebl@debian.org> - 2016-01-04 18:20 +0100
Re: Prevent shutdown with systemctl Floris <jkfloris@dds.nl> - 2016-01-04 20:10 +0100
Re: Prevent shutdown with systemctl Floris <jkfloris@dds.nl> - 2016-01-04 21:00 +0100
Re: Prevent shutdown with systemctl Michael Biebl <biebl@debian.org> - 2016-01-04 21:20 +0100
Re: Prevent shutdown with systemctl Brian <ad44@cityscape.co.uk> - 2016-01-04 21:50 +0100
Re: Prevent shutdown with systemctl Floris <jkfloris@dds.nl> - 2016-01-04 23:50 +0100
Re: Prevent shutdown with systemctl Michael Biebl <biebl@debian.org> - 2016-01-05 00:50 +0100
Re: Prevent shutdown with systemctl Brian <ad44@cityscape.co.uk> - 2016-01-05 01:30 +0100
Re: Prevent shutdown with systemctl Michael Biebl <biebl@debian.org> - 2016-01-05 01:40 +0100
Re: Prevent shutdown with systemctl Gary Dale <garydale@torfree.net> - 2016-01-04 18:20 +0100
Re: Prevent shutdown with systemctl <tomas@tuxteam.de> - 2016-01-04 18:50 +0100
Re: Prevent shutdown with systemctl Stuart Longland <stuartl@longlandclan.id.au> - 2016-01-04 21:20 +0100
Re: Prevent shutdown with systemctl Gary Dale <garydale@torfree.net> - 2016-01-04 21:40 +0100
Re: Prevent shutdown with systemctl Stuart Longland <stuartl@longlandclan.id.au> - 2016-01-04 22:10 +0100
Re: Prevent shutdown with systemctl Gary Dale <garydale@torfree.net> - 2016-01-04 22:50 +0100
Re: Prevent shutdown with systemctl Michael Biebl <biebl@debian.org> - 2016-01-05 01:20 +0100
Re: Prevent shutdown with systemctl Gary Dale <garydale@torfree.net> - 2016-01-05 18:20 +0100
Re: Prevent shutdown with systemctl Gary Dale <garydale@torfree.net> - 2016-01-04 21:30 +0100
Re: Prevent shutdown with systemctl Stuart Longland <stuartl@longlandclan.id.au> - 2016-01-04 22:00 +0100
Re: Prevent shutdown with systemctl David Wright <deblis@lionunicorn.co.uk> - 2016-01-05 05:50 +0100
Re: Prevent shutdown with systemctl <tomas@tuxteam.de> - 2016-01-04 22:20 +0100
Re: Prevent shutdown with systemctl Gary Dale <garydale@torfree.net> - 2016-01-04 22:50 +0100
Re: Prevent shutdown with systemctl David Wright <deblis@lionunicorn.co.uk> - 2016-01-05 06:10 +0100
Symlinks vs. hardlinks [was: Prevent shutdown with systemctl] <tomas@tuxteam.de> - 2016-01-05 09:40 +0100
Re: Symlinks vs. hardlinks "Thomas Schmitt" <scdbackup@gmx.net> - 2016-01-05 11:10 +0100
Re: Symlinks vs. hardlinks <tomas@tuxteam.de> - 2016-01-05 11:40 +0100
Re: Symlinks vs. hardlinks [was: Prevent shutdown with systemctl] <tomas@tuxteam.de> - 2016-01-05 16:30 +0100
Re: Symlinks vs. hardlinks [was: Prevent shutdown with systemctl] David Wright <deblis@lionunicorn.co.uk> - 2016-01-05 16:30 +0100
Re: Prevent shutdown with systemctl Jude DaShiell <jdashiel@panix.com> - 2016-01-04 19:20 +0100
Re: Prevent shutdown with systemctl Brian <ad44@cityscape.co.uk> - 2016-01-04 19:30 +0100
Re: Prevent shutdown with systemctl jdd <jdd@dodin.org> - 2016-01-04 20:10 +0100
Re: Prevent shutdown with systemctl jdd <jdd@dodin.org> - 2016-01-04 20:30 +0100
Re: Prevent shutdown with systemctl Chris Bannister <cbannister@slingshot.co.nz> - 2016-01-05 11:10 +0100
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