Chmod -R 777 / on ubuntu – numerous problems

chmodrootsudo

A client has accidentally given the entire filesystem full permissions on their ubuntu 10.04 box.

chmod -R 777 httpdocs/cd /

As you can see they attempted to cd to the root, and instead gave chmod a fun parameter to play with.

First sign of the problem was inability to use 'su', giving an authentication error. sudo also complained of a missing setuid bit. This was fixed by logging in as root from the machine itself, and running chmod +s /usr/bin/sudo.

I can now sudo su and do what I need to as root. su still gives an authentication failure.

I followed the advice here: http://swiss.ubuntuforums.org/showthread.php?t=1180661&page=2

chmod 0755 /
chmod 0755 /*
chmod 1777 /tmp
chmod 0750 /root
chmod 0700 /lost+found

I then tried to reset root password. I still cannot su to become root, or su root.

The system seems to be running fine. Are there any suggestions for getting su to work once again? Where can I look for more problems?

Best Answer

I would actually consider doing a full reinstall of the system. Even if you manage to get most permissions right and that things seem to work there will most likely be some special permissions laying around, just waiting to cause trouble.

Alternatively I'd compare the permission with a second, possibly freshly installed, machine. Shouldn't be to hard together with your favorite scripting language.

Related Solutions

Ubuntu – Undoing chmod 777

There's an easy way to back up and restore permissions amd ownerships of a directory tree using the ACL tools. It works even if you don't have ACLs enabled on the filesystem.

getfacl -R >saved-permissions
setfacl --restore=saved-permissions

Most permission issues will cause a “permission denied” error message to appear somewhere, either on the console or in some log file.

A powerful tool to investigate file access issues is strace. It shows the system calls made by a process. The output can be difficult to understand, but it's relatively easy to see what files the program is trying to access and why it can or cannot find what it wants. Usage examples:

strace -s9999 -o myprogram.strace myprogram  # trace myprogram
strace -s9999 -fF ...                        # also trace subprocesses
strace -s9999 -p12345                        # connect to running process by PID
strace -s9999 -efile ...                     # only show filesystem calls
strace -eaccess,open,stat,lstat              # only show common file access calls

Revert chmod 777 / -R

Wow... that's pretty bad... The best thing you can do now is back up your personal data and reinstall your system.

Since that's probably not what you wanted to hear, the second best (and probably substantially more painful) thing to do is something like:

for package in `dpkg -l | awk '{print $2}'`; do
    apt-get install --reinstall $package
done

Note that this fix is purely theoretical (I've never tried it), but it will reinstall every package on your system (because as far as I can tell apt and dpkg don't have a "fix permissions" function like RPM). Reinstalling should fix the permissions on all the files that are in packages.

This "fix" may break other things, and you will probably still have some 777'd files floating around that aren't part of any packages, so you should follow up by finding all the stuff that's mode 777 and making sure the list looks sane.

Best Answer

Related Solutions

Ubuntu – Undoing chmod 777

Revert chmod 777 / -R

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