qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Qemu-devel] [Bug 807893] Re: qemu privilege escalation


From: Andrew Griffiths
Subject: [Qemu-devel] [Bug 807893] Re: qemu privilege escalation
Date: Mon, 18 Jul 2011 10:15:40 -0000

Here's some reproduction code you can use to see the difference between
glibc and raw system calls:

https://gist.github.com/1084042

If you're wondering about Linux and non-glibc distributions using qemu,
Alpine is one particular answer to that question (so the affected Linux
distributions is non-zero).

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/807893

Title:
  qemu privilege escalation

Status in QEMU:
  Confirmed

Bug description:
  If qemu is started as root, with -runas, the extra groups is not
  dropped correctly

  /proc/`pidof qemu`/status
  ..
  Uid:    100     100     100     100
  Gid:    100     100     100     100
  FDSize: 32
  Groups: 0 1 2 3 4 6 10 11 26 27 
  ...

  The fix is to add initgroups() or setgroups(1, [gid]) where
  appropriate to os-posix.c.

  The extra gid's allow read or write access to other files (such as
  /dev etc).

  Emulating the qemu code:

  # python
  ...
  >>> import os
  >>> os.setgid(100)
  >>> os.setuid(100)
  >>> os.execve("/bin/sh", [ "/bin/sh" ], os.environ)
  sh-4.1$ xxd /dev/sda | head -n2
  0000000: eb48 9000 0000 0000 0000 0000 0000 0000  .H..............
  0000010: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  sh-4.1$ ls -l /dev/sda
  brw-rw---- 1 root disk 8, 0 Jul  8 11:54 /dev/sda
  sh-4.1$ id
  uid=100(qemu00) gid=100(users) 
groups=100(users),0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel),11(floppy),26(tape),27(video)

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/807893/+subscriptions



reply via email to

[Prev in Thread] Current Thread [Next in Thread]