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Why might sudo chmod -R a+w * cause

sudo: /etc/sudoers is mode 0640, should be 0440 sudo:   
no valid sudoers sources found, quitting

and how might it be made to work?

Jorge Castro
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jacknad
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  • Possible duplicate http://askubuntu.com/questions/50704/sudo-error-is-mode-0777-should-be-0440?rq=1 –  Sep 17 '12 at 16:23
  • possible duplicate of http://askubuntu.com/questions/50704/sudo-error-is-mode-0777-should-be-0440?rq=1 – Ankit Sep 17 '12 at 16:43

2 Answers2

10

I think your best bet is to start the system in recovery mode (see here for instructions), drop to root shell and do chmod 0440 /etc/sudoers.

EDIT: as Mik suggested below, the following should work as well without rebooting the system:

pkexec chmod 0440 /etc/sudoers
Community
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January
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    You could also try using `pkexec chmod 0440 /etc/sudoers` without going into recovery mode. –  Sep 17 '12 at 16:28
  • Thanks a million! BTW: also had to `pkexec chmod 0440 /etc/sudoers.d/README`. I wonder if I broke anything else in /etc. Meh. – jacknad Sep 17 '12 at 17:16
  • @Mik Thanks a lot. You have saved me so much time. I thought I'd have to re-install Ubuntu. Although can you tell me: Now that most of the system is 0777 permitted, is it dangerous to work on internet? – Aayush Dec 01 '12 at 07:08
  • @Aayush Although we can't really discuss it here, see [this answer](http://askubuntu.com/questions/20105/for-security-reasons-why-should-var-www-not-have-chmod-777) regarding 777 permissions and refer to other questions on the site for resetting the correct permissions on files and directories. –  Dec 03 '12 at 20:07
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Why might the command cuase this to happen? I suspect you ran the command while your current directory was /etc!

sudo refuses to work if the permissions of /etc/sudoers have been tamprered with to avoid compromising the system. You will have to fix the permissions using recovery mode unless you have another way of getting root access.

StarNamer
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