[Qemu-commits] [qemu/qemu] e586ed: virtiofs: drop remapped security.capability xattr ...

[Peter Maydell]

  Branch: refs/heads/master
  Home:   https://github.com/qemu/qemu
  Commit: e586edcb410543768ef009eaa22a2d9dd4a53846
      
https://github.com/qemu/qemu/commit/e586edcb410543768ef009eaa22a2d9dd4a53846
  Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
  Date:   2021-03-04 (Thu, 04 Mar 2021)

  Changed paths:
    M docs/tools/virtiofsd.rst
    M tools/virtiofsd/passthrough_ll.c

  Log Message:
  -----------
  virtiofs: drop remapped security.capability xattr as needed

On Linux, the 'security.capability' xattr holds a set of
capabilities that can change when an executable is run, giving
a limited form of privilege escalation to those programs that
the writer of the file deemed worthy.

Any write causes the 'security.capability' xattr to be dropped,
stopping anyone from gaining privilege by modifying a blessed
file.

Fuse relies on the daemon to do this dropping, and in turn the
daemon relies on the host kernel to drop the xattr for it.  However,
with the addition of -o xattrmap, the xattr that the guest
stores its capabilities in is now not the same as the one that
the host kernel automatically clears.

Where the mapping changes 'security.capability', explicitly clear
the remapped name to preserve the same behaviour.

This bug is assigned CVE-2021-20263.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>


  Commit: cb90ecf9349198558569f6c86c4c27d215406095
      
https://github.com/qemu/qemu/commit/cb90ecf9349198558569f6c86c4c27d215406095
  Author: Peter Maydell <peter.maydell@linaro.org>
  Date:   2021-03-04 (Thu, 04 Mar 2021)

  Changed paths:
    M docs/tools/virtiofsd.rst
    M tools/virtiofsd/passthrough_ll.c

  Log Message:
  -----------
  Merge remote-tracking branch 
'remotes/dgilbert-gitlab/tags/pull-virtiofs-20210304' into staging

virtiofs minor security fix

Fix xattrmap to drop remapped security.capability capabilities.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

# gpg: Signature made Thu 04 Mar 2021 10:36:45 GMT
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" 
[full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert-gitlab/tags/pull-virtiofs-20210304:
  virtiofs: drop remapped security.capability xattr as needed

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>


Compare: https://github.com/qemu/qemu/compare/c40ae5a3ee38...cb90ecf93491