chvt issue

[Alessandro Sappia]

HI all
I was reading vt driver
and I saw
        /*
         * To have permissions to do most of the vt ioctls, we either have
         * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
         */
        perm = 0;
        if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
                perm = 1;

(lines 382-388 - drivers/char/vt_ioctl.c)

After reading the comment I thinked I can change vt
from one of my own to another one of mine.

so I opened vc/2 and vc/3 and a pts/0
$ w
 01:26:45 up  1:33,  5 users,  load average: 0,84, 0,66, 0,97
USER     TTY        LOGIN@   IDLE   JCPU   PCPU WHAT
alx      vc/2      01:07   18:51   0.00s  0.00s -bash
alx      vc/3      01:25   48.00s  0.00s  0.00s -bash
alx      :0        23:55   ?xdm?   4:21   0.84s gnome-session
alx      pts/0     01:22    0.00s  0.08s  0.00s w

I went to vc/3 and I did
 $ tty
/dev/vc/3
 $ chvt 2
as i expected I changed my tty to 2
after that I tryied to do the same from pts/0
and

 $ tty
/dev/pts/0
 $ chvt 2
chvt: VT_ACTIVATE: Operation not permitted
 $

After that I went in vc/2
and I did
 $ chvt 12
after that i was watching at my syslog writing messages...
I tryed the same from pts/0
and
 $ chvt 12
Couldnt get a file descriptor referring to the console

So, there are some things I couldn't get about virtual terminal ioctls 
and fd...
please note that use chvt having CAP_SYS_TTY_CONFIG (root) works fine.

Is it possible to change terminal from an unprivileged user ?

THanks in advance
for the time you'll spend answering me.

Alessandro
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