As for the setuid solution I have come up with I understand that it is not a completely secure solution. Other users can view the envfile.txt contents by running the setuid script using eval `/tmp/filereader.pl /tmp/envfile.txt`.
It's worse than that. Any user who can run filereader.pl can get the contents of the env file.
Quote:
But i just tbought until I come up with a more secure solution this would be at least safer than having no Setuid script at all and giving read permission to all to /tmp/envfile.txt and using . /tmp/envfile.txt inside the shell script.
Rename filereader.pl to hackers-please-ignore.pl and you'll understand how insecure this really is. It's not better, it's worse.
Quote:
Corona,
As for your suggestion that i create a shell script filreader.sh owned by master account that has read access to envfile.txt and which is shielded from read/execute access by other users and which has inside it
Now inside the main script test.sh that other userids can execute i include
This would work.
Why bother using reader.pl? The script master script was already secured.
Quote:
But again it would expose a threat in that other user ids can use a simple hack in the form of a script like this which prints the contents of envfile.txt
1) sudo does not inherit shell options like -x. It excludes almost everything in fact.
2) Users can't do sudo -u masteraccount filereader.sh unless you told sudo to let them run filereader.sh as masteraccount. If you don't want to let them do that, don't tell sudo to let them do that.
The Key point here I was not aware of is that SUDO does not inherit shell options like -x. That helps thanks.
Since I do not have root access to modify /etc/sudoers at work I tested this out on my Mac Pro that runs underlying OS Darwin 10.8 BSD/OSX based Linux.
First as root I added the following entry to /etc/sudoers so that user 'otheruser' has sudo permission to run the command owned by admin account. Note that on Mac OS, in addition to admin there is also root user.
As admin user 'admin' I created the following files which have no read/execute permission to group and others
Then I created following script with 'otheruser' which just sources above admin script without using Sudo
Obviously it fails like below due to no read/execute permission
Then I updated this 'otheruser' script to use sudo instead of directly calling it as below
Now when I invoked this script by 'otheruser' I got the following output which shows that even though the admin script got execute fine, envfile.txt contents are hidden as sudo does not inherit -x oiption
On the other hand when I used xtrace option set -x within a script owned by 'admin' user as below, where it invokes the script directly without using sudo, the xtrace output prints the entries of the envfile.txt as they are parsed
Output
So this proves your theory that sudo doesnot inherit -x option meaning a secure script owned by admin that sources a secure env file, can be granted sudo access to other users without the risk of those user being able to trace envfile contents with the Xtrace option.
The semi-colons are necessary as command separators.
But I'm still wondering why you want to make an environment file unreadable by certain users. All they have to do is type "env" to see everything you put in there anyways. (and "alias")
But I'm still wondering why you want to make an environment file unreadable by certain users. All they have to do is type "env" to see everything you put in there anyways.
I suspect it's paths and passwords for a database, and that the shell script in question just uses the database and doesn't give the user a shell prompt to play with.
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