Created attachment 863319 [details]
sesh loginshell argv[0] replacement patch

Description of problem:

/usr/libexec/sesh if called as -sesh by sudo executes the login shell with wrongly replaced argv[0]. The last "/" is replaced with "-", but the rest of the path remains intact. I expect login shell should be called as "-shell", not "/bin-shell".

This can cause unexpected behaviour e.g. in case /bin/zsh which thinks it was called as /bin-zsh, thus runs in sh emulation mode because bin-zsh starts with "b".

Version-Release number of selected component (if applicable):

sudo-1.8.6p3-12.el6.x86_64

How reproducible:

Always

Steps to Reproduce:
1. add

%wheel	ALL=(ALL) ROLE=unconfined_r TYPE=unconfined_t NOPASSWD: ALL

to sudoers (this triggers sesh, without selinux context specified sesh isn't involved)

2. # chsh -s /bin/zsh

3. # usermod -G wheel zshuser

4. [zshuser@rhel6]~% sudo -i

Actual results:

only

#

prompt is shown, no zsh specific rc scripts are sourced in sh emulation mode
 
In strace we see:

execve("/bin/zsh", ["/bin-zsh"], ...

Expected results:

[root@rhel62]~# 

prompt is shown, zsh is launched without emulation

In strace we see:

execve("/bin/zsh", ["-zsh"], ...

Additional info:

Reproduces in sudo-1.8.8-1.fc20.x86_64 as well

Patch attached