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I have a linux development servers with some projects in home folders belonging to different users. Due to the nature of the server, some users can do sudo -s for some administrative task. Is there any way I can prevent users from snooping other home folders (or a specific folder)?

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    Yes, don't give them root access via sudo or any other method. Feb 14, 2017 at 17:48
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    Avoid giving them root access by using a program that runs a command as root but only whitelisted commands. No idea if this would work. Feb 14, 2017 at 18:44

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If a user runs a command with sudo then they are running the command as if they were root, because they are root. So you cannot prevent a user that can use sudo from switching to a directory.

If you don't want users to access files in a directory, you can't give them root access on the machine.

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  • Encrypting wouldn't help. That protects against someone who steals the hard drive, not against someone who can run commands on the machine while the files are accessible. Feb 14, 2017 at 23:37
  • You can encrypt a file with gpg for example. You password encrypt it and only you know that password, other users do not.
    – ProdIssue
    Feb 15, 2017 at 0:04
  • But if someone is root then they can read the file as soon as the legitimate user enters the password, and they can read the password too. Feb 15, 2017 at 0:09
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If someone can run arbitrary commands as root, then they can switch to any user account, so they can do whatever that user can do.

In practice you have three options.

  • The privileged users only need to perform very specific tasks. Then let them only run some specific commands with sudo. This is secure only if those commands don't allow “shell escapes”, i.e. if there's no way to leverage those commands to execute other programs. For example, package management (allowing sudo apt-get install …) often allows shell escapes by injecting the commands inside a package (this can be ok if package signatures are checked properly from known sources).
  • The privileged users need administrative powers, but they don't need it on the “real” computer, all they need is to have it on some computer (e.g. to play with network settings). Then create virtual environments (e.g. a virtual machine, or an lxc container, or an ad hoc Linux namespace) for the privileged users, and don't make other users' data available in the virtual environments.
  • Use social rather than technical controls: give the users broad permissions but let them know that any violation of privacy will be harshly dealt with. This is often ok if the users are employees, but it depends on how sensitive the data is.
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Depending on what they need to be able to do, you can give them sudo access to only certain commands by dropping a line like this into your sudoers file:

%devgroup ALL=(ALL): /bin/commandname

which would make it so members of the group devgroup can only execute /bin/commandname as root (and of course with this particular example, you'd also want to remove them from the wheel group).

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