Re: bug in [ -f file ] test

[László Házy]

Yes, SELinux is active.

On Wed, 2016-07-27 at 17:55 +0200, Reuti wrote:

> > Am 27.07.2016 um 17:36 schrieb László Házy <hazy_l@yahoo.com>:
> >
> > Yes, user2 has rx access to /home/user1. This is done by the first command in the list of commands, namely: "[user1]$ chmod g+rx /home/user1". The two users are part of the same group.
> >
> > An even more troublesome variation, involving root, is the following:
> >
> > [user1]$ touch file; ls -l file
> > -rw-r--r--. 1 user1 users    0 Jul 26 15:24 file
>
>
> The dot at the end means SELinux ACL IIRC - are you running SELinux?
>
> -- Reuti
>
>
> > [user1]$ ln -s /home/user1/file /var/tmp/link
> > [user1]$ ls -l /var/tmp/link
> > lrwxrwxrwx. 1 user1 users 17 Jul 26 15:26 /var/tmp/link -> /home/user1/file
> >
> > [user1]$ [[ -f /var/tmp/link ]]; echo $?
> > 0
> >
> > [user1]$ su 
> > [root]$ [[ -f /var/tmp/link ]]; echo $?
> > 1
> >
> >
> > On Tue, 2016-07-26 at 23:26 +0200, Reuti wrote:
> > > Am 26.07.2016 um 23:07 schrieb László Házy:
> > >
> > >
> > > > Hmm, interesting. I can reproduce your results. Thanks.
> > > > However, note the following:
> > > >
> > > > [user1]$ chmod g+rx /home/user1
> > > > [user1]$ touch file; ls -l file
> > > > -rw-r--r--. 1 user1 users    0 Jul 26 15:24 file
> > > >
> > > > [user1]$ su user2 -c "ln -s /home/user1/file /var/tmp/link"
> > > > [user1]$ ls -l /var/tmp/link
> > > > lrwxrwxrwx. 1 user2 users 17 Jul 26 15:26 /var/tmp/link -> /home/user1/file
> > > >
> > > > [user1]$ [[ -f /var/tmp/link ]]; echo $?
> > > > 1
> > > >
> > > > [user1]$ su user2
> > > > [user2]$ [[ -f /var/tmp/link ]]; echo $?
> > > > 0
> > > >
> > > > Something does not add up.
> > >
> > >
> > > Does user2 have rx access to /home/user1?
> > >
> > > -- Reuti
> > >
> > >
> > >
> > > > >From experimenting, it appears that only the user who created the symlink will get true for the file test.
> > > >
> > > > Thank you.
> > > >
> > > >
> > > >
> > > >
> > > > On Tue, 2016-07-26 at 15:06 -0400, Grisha Levit wrote:
> > > >
> > > > > Are you sure "file" is a link to an actual file, not, say, a directory?
> > > > >
> > > > > $ rpm -q bash; echo $BASH_VERSION; cat /etc/redhat-release
> > > > > bash-4.3.42-3.fc23.x86_64
> > > > > 4.3.42(1)-release
> > > > > Fedora release 23 (Twenty Three)
> > > > >
> > > > > $ touch file; ln -s file link; [[ -f link ]]; echo $?
> > > > > 0
> > > > >
> > > > > On Tue, Jul 26, 2016 at 12:58 PM, László Házy <
> > > > > hazy_l@yahoo.com
> > > > > > wrote:
> > > > >
> > > > > > I am running bash 4.3.42-3 on Fedore Core 23.
> > > > > >
> > > > > > I noticed that the [ -f file ] test returns false if "file" is a symlink. Given the intended behavior (from a long time ago), this is wrong as the symlinks are supposed to be followed. It certainly brakes functionality in certain existing software.
> > > > > >
> > > > > > Has the default behavior been changed somewhere along the time line and I am not aware of it?