[Qemu-devel] [V11 00/15] virtio-9p: Use chroot to safely access files in passthrough security model

["M. Mohan Kumar" <mohan@in.ibm.com>]

In passthrough security model, following symbolic links in the server
side could result in TOCTTOU vulnerabilities.
(http://en.wikipedia.org/wiki/Time-of-check-to-time-of-use)

This patchset resolves this issue by creating a dedicated process which
chroots into the share path and all file object access is done in the
chroot environment.

This patchset implements chroot enviroment, provides necessary functions
that can be used by the passthrough function calls.

This patchset is rebased on top of 9p coroutines patches posted to
qemu-devel list
http://lists.nongnu.org/archive/html/qemu-devel/2011-05/msg02796.html

Changes from version V10:
* Added support to do lstat and readlink from chroot process
* Fixed an issue with dealing fds when qemu process reached maxfds limit

Changes from version V9:
* Error handling in special file object creation in virtio-9p-local.c

Changes from version V8:
* Make chmod and chown also operate under chroot process
* Check for invalid path requests, minor cleanups

Changes from version V7:
* Add two chroot methods remove and rename
* Minor cleanups like consolidating functions

Changes from version V6:
* Send only fd/errno in socket operations instead of FdInfo structure
* Minor cleanups

Changes from version V5:
* Return errno on failure instead of setting errno
* Minor cleanups like updated comments, enable CONFIG_THREAD if
  CONFIG_VIRTFS is enabled

Changes from version V4:
* Avoid using malloc/free inside chroot process
* Seperate chroot server and client functions

Changes from version V3
* Return EIO incase of socket read/write fail instead of exiting
* Changed data types as suggested by Blue Swirl
* Chroot process reports error through qemu process

Changes from version V2
* Treat socket IO errors as fatal, ie qemu will exit
* Split patchset based on chroot side (server) and qemu side(client)
  functionalities

M. Mohan Kumar (15):
  Implement qemu_read_full
  virtio-9p: Enable CONFIG_THREAD if CONFIG_VIRTFS is enabled
  virtio-9p: Provide chroot worker side interfaces
  virtio-9p: Add qemu side interfaces for chroot environment
  virtio-9p: Add support to open a file in chroot environment
  virtio-9p: Create support in chroot environment
  virtio-9p: Support for creating special files
  virtio-9p: Add support for removing file or directory
  virtio-9p: Add support to rename
  virtio-9p: Move file post creation changes to none security model
  virtio-9p: Add support for chmod
  virtio-9p: Add support for chown
  virtio-9p: Chroot environment for other functions
  virtio-9p: Add stat functionality to chroot
  virtio-9p: Add readlink support to chroot

 Makefile.objs                     |    1 +
 configure                         |    1 +
 fsdev/file-op-9p.h                |    3 +
 hw/9pfs/virtio-9p-chroot-worker.c |  418 +++++++++++++++++++++++++++++++++++++
 hw/9pfs/virtio-9p-chroot.c        |  174 +++++++++++++++
 hw/9pfs/virtio-9p-chroot.h        |   54 +++++
 hw/9pfs/virtio-9p-device.c        |   24 ++
 hw/9pfs/virtio-9p-local.c         |  248 ++++++++++++++++++----
 osdep.c                           |   32 +++
 qemu-common.h                     |    2 +
 10 files changed, 910 insertions(+), 47 deletions(-)
 create mode 100644 hw/9pfs/virtio-9p-chroot-worker.c
 create mode 100644 hw/9pfs/virtio-9p-chroot.c
 create mode 100644 hw/9pfs/virtio-9p-chroot.h

-- 
1.7.5.1