On Sat, Jul 9, 2011 at 10:22 AM, Stefan Hajnoczi <stefa...@linux.vnet.ibm.com> wrote: > Andrew Griffiths reports that -runas does not set supplementary group > IDs. This means that gid 0 (root) is not dropped when switching to an > unprivileged user. > > Add an initgroups(3) call to use the -runas user's /etc/groups > membership to update the supplementary group IDs. > > Signed-off-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com> > --- > Note this needs compile testing on various POSIX host platforms. Tested on > Linux. Should work on BSD and Solaris. initgroups(3) is SVr4/BSD but not in > POSIX. > > os-posix.c | 6 ++++++ > 1 files changed, 6 insertions(+), 0 deletions(-)
Are you happy with this patch? Bumping because security-related. Regarding portability, Linux, BSD, Solaris, and Mac OS X all provide initgroups(3). I think we're good. Stefan -- 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
