[SOLVED] sudo giving permission denied on Linux

ankgup87 · 02-28-2012, 11:01 PM

I have a RHEL 5 machine on which I'm trying to run sudo.

I have created a test-eng user and added it in the sudoers file. The sudoers file have the correct permissions 0440. The output of sudoers file is :

User_Alias FULLTIME=test-eng
FULLTIME ALL=(ALL) NOPASSWD: ALL

I have given the correct setuid permissions to sudo as well. But when i run sudo after logging in from the test-eng user I get permission denied. Have tried almost everything but it doesn't work.

/usr/bin/sudo: Permission denied.

Also the same thing worked for me on a 64 bit machine and this one is a 32 bit machine. So I'm wondering whether this might be a 32/64 bit issue. Please help.

Dark_Helmet · 02-28-2012, 11:43 PM

The error you report sounds like a basic file permission problem--that user "test-eng" is denied read permission, execute permission, or both for the sudo command.

So, what are the permissions on the actual sudo file? On my Ubuntu 10.04 system:

Code:

user@localhost$ ls -l `which sudo`
-rwsr-xr-x 2 root root 148024 2011-01-19 12:01 /usr/bin/sudo

Valery Reznic · 02-28-2012, 11:49 PM

what

Code:

ls -l /usr/bin/sudo

shows?

ankgup87 · 02-29-2012, 12:03 AM

Quote:

Originally Posted by Dark_Helmet

The error you report sounds like a basic file permission problem--that user "test-eng" is denied read permission, execute permission, or both for the sudo command.

So, what are the permissions on the actual sudo file? On my Ubuntu 10.04 system:

Code:

user@localhost$ ls -l `which sudo`
-rwsr-xr-x 2 root root 148024 2011-01-19 12:01 /usr/bin/sudo

ls -l sudo shows the following output

-r--r----- 1 root root 98840 Feb 29 13:25 sudo

---------- Post added 02-29-12 at 01:04 AM ----------

Quote:

Originally Posted by Valery Reznic

what

Code:

ls -l /usr/bin/sudo

shows?

ls -l sudo shows the following output

-r--r----- 1 root root 98840 Feb 29 13:25 sudo

ankgup87 · 02-29-2012, 12:07 AM

Quote:

Originally Posted by Dark_Helmet

The error you report sounds like a basic file permission problem--that user "test-eng" is denied read permission, execute permission, or both for the sudo command.

So, what are the permissions on the actual sudo file? On my Ubuntu 10.04 system:

Code:

user@localhost$ ls -l `which sudo`
-rwsr-xr-x 2 root root 148024 2011-01-19 12:01 /usr/bin/sudo

One thing I notice is that "which sudo" is not giving the correct output:

/usr/bin/which: no sudo in (/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin)

Dark_Helmet · 02-29-2012, 12:09 AM

Quote:

Originally Posted by ankgup87

-r--r----- 1 root root 98840 Feb 29 13:25 sudo

The permissions do not allow anyone to execute the sudo program. That is not correct.

run this command (copy-paste it if necessary), as root:

Code:

chmod 4755 `which sudo`

Then try using sudo as the "test-eng" user again.

EDIT:

Quote:

Originally Posted by ankgup87

One thing I notice is that "which sudo" is not giving the correct output:

/usr/bin/which: no sudo in (/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin)

Then what directory contains sudo? Specifically. Give the full path to the file.

EDIT2:
Perhaps more appropriately, how did you install sudo? From a package manager, from a source code tarball, or some other option?

ankgup87 · 02-29-2012, 12:13 AM

Quote:

Originally Posted by Dark_Helmet

The permissions do not allow anyone to execute the sudo program. That is not correct.

run this command (copy-paste it if necessary), as root:

Code:

chmod 4755 `which sudo`

Then try using sudo as the "test-eng" user again.

EDIT:

Then what directory contains sudo? Specifically. Give the full path to the file.

On changing the permissions to 4755, I'm getting the following error while running sudo from test-eng user:

/usr/bin/sudo: Exec format error. Wrong Architecture.

I think sudo has to have 4111 permissions to have the other users use root uid. This is what I read on some other posts.

EDIT:

I copied it from another machine on which it was working fine

EDIT2:
Currently sudo is in /usr/bin/sudo

I changed the permissions with the following command

chmod 4755 /usr/bin/sudo

Dark_Helmet · 02-29-2012, 12:22 AM

Quote:

Originally Posted by ankgup87

I copied it from another machine on which it was working fine

No, no... don't do that Install it using the RHEL package manager. It's probably something like:

Code:

yum install sudo

Otherwise, download, compile, and install a source code version:
Sudo download page

Do not copy an executable from one machine to another unless the machines are identical. Even then, you probably would miss some support files (e.g. visudo which you must use to configure sudo properly).

Quote:

Originally Posted by ankgup87

I think sudo has to have 4111 permissions to have the other users use root uid.

You can change the permissions to whatever you like. All I will say is that the permissions I provided are the exact permissions on my sudo command for my Ubuntu box. My sudo works fine on that machine. RHEL might be different.

EDIT:

Quote:

Originally Posted by ankgup87

/usr/bin/sudo: Exec format error. Wrong Architecture.

That's a clear indication that the problem is an inconsistency between the source machine and the destination machine. It could be 32/64 bit incompatibility, it could be that one machine is Intel/AMD and the other is ARM/PowerPC, etc.

ozanbaba · 02-29-2012, 12:25 AM

What does "file /usr/bin/sudo" says. Because "/usr/bin/sudo: Exec format error. Wrong Architecture." error points an architectural mismatch. (Like trying to run 64-bit sudo on 32-bit system).

ankgup87 · 02-29-2012, 12:29 AM

Quote:

Originally Posted by ozanbaba

What does "file /usr/bin/sudo" says. Because "/usr/bin/sudo: Exec format error. Wrong Architecture." error points an architectural mismatch. (Like trying to run 64-bit sudo on 32-bit system).

file /usr/bin/sudo says:

/usr/bin/sudo: setuid ELF 64-bit LSB executable, AMD x86-64, version 1 (SYSV), for GNU/Linux 2.4.0, dynamically linked (uses shared libs), for GNU/Linux 2.4.0, stripped

And this is a 32 bit machine. I think that is the problem. Right?

ankgup87 · 02-29-2012, 12:30 AM

Quote:

Originally Posted by Dark_Helmet

No, no... don't do that Install it using the RHEL package manager. It's probably something like:

Code:

yum install sudo

Otherwise, download, compile, and install a source code version:
Sudo download page

Do not copy an executable from one machine to another unless the machines are identical. Even then, you probably would miss some support files (e.g. visudo which you must use to configure sudo properly).

You can change the permissions to whatever you like. All I will say is that the permissions I provided are the exact permissions on my sudo command for my Ubuntu box. My sudo works fine on that machine. RHEL might be different.

EDIT:

That's a clear indication that the problem is an inconsistency between the source machine and the destination machine. It could be 32/64 bit incompatibility, it could be that one machine is Intel/AMD and the other is ARM/PowerPC, etc.

Thanks. I will try to install a fresh sudo and will update the results

EDIT:

I downloaded a new sudo for 32 bit and it worked.
I will make sure I don't copy it from another machine of a different configuration.
Thanks for your help Dark Helmet. Marking this thread as RESOLVED.