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Old 12-10-2009, 10:15 AM   #1
saagar
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Registered: Jul 2008
Location: Chennai, India
Distribution: RHEL5, Ubuntu
Posts: 191

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A question on SUID (Set User ID)


Friends,

Suppose root user is setting a file script.sh with SUID permission and allowing others to have execute permissions as follows:

Code:
 #ls -l /script.sh
-rwsr--r-x root root ---- script.sh
And then he is writing a script as follows:
Code:
#vi /script.sh
	#!/bin/bash
	touch /root/newfile.txt
	:wq!
Now, a normal user is logging in and executes that file:

Code:
#su - normaluser
[normaluser@linux1~]$cd /
[normaluser@linux1~]$./script.sh
touch: cannot touch `/root/newfile.txt': Permission denied
Actually, after setting SUID to a script, and if a normaluser executes that file, he should be able to write a file inside /root directory, since the effective UID is that of root user's. why is it not happening in this case? Please help.

Last edited by saagar; 12-10-2009 at 10:16 AM.
 
Old 12-10-2009, 10:22 AM   #2
cantab
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I've a feeling SUID doesn't work for shell scripts, only for binary executables.
 
Old 12-10-2009, 10:29 AM   #3
jschiwal
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Cantab is correct. Suid isn't supported in Linux for scripts.
 
Old 12-10-2009, 12:51 PM   #4
saagar
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Registered: Jul 2008
Location: Chennai, India
Distribution: RHEL5, Ubuntu
Posts: 191

Original Poster
Rep: Reputation: 37
cantab and jschiwal, thanks for your respnoses.
 
  


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