Thread (49 messages) 49 messages, 11 authors, 2017-06-04

[kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN

From: Alan Cox <hidden>
Date: 2017-05-30 23:56:56
Also in: lkml

This is my point. Apps will continue to shoot themselves in the foot. Of course
the correct response to one of these vulns is to not pass ttys across a
security boundary. We have an opportunity here to reduce the impact of this bug
class at the kernel level. 
Not really.

If you pass me your console for example I can mmap your framebuffer and
spy on you all day. Or I could reprogram your fonts, your keyboard, your
video mode, or use set and paste selection to write stuff. If you are
using X and you can't get tty handles right you'll no doubt pass me a
copy of your X file descriptor in which case I own your display, your
keyboard and your mouse and I don't need to use TIOCSTI there either.

There are so many different attacks based upon that screwup that the
kernel cannot defend against them. You aren't exactly reducing the impact.

Alan
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