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.
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