On 03/25/2013 08:25 AM, Paolo Bonzini wrote:
> The need_prctl variable is not really needed. If it is false,
> capng_apply will be called twice with the same set, causing
> a little extra work but no problem. This keeps the code a bit
> simpler.
>
> It is also clearer to invoke capng_apply(CAPNG_SELECT_BOUNDS)
> separately, to make sure it is done while we have CAP_SETPCAP.
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> src/util/virutil.c | 18 +++++++++++-------
> 1 file changed, 11 insertions(+), 7 deletions(-)
> /* Change to the temp capabilities */
> - if ((capng_ret = capng_apply(CAPNG_SELECT_BOTH)) < 0) {
> + if ((capng_ret = capng_apply(CAPNG_SELECT_CAPS)) < 0) {
Beforehand, we limited both caps and bounding set, with an overlarge
set, now you are limiting just caps...
> virReportError(VIR_ERR_INTERNAL_ERROR,
> _("cannot apply process capabilities %d"), capng_ret);
> goto cleanup;
> @@ -3063,12 +3061,18 @@ virSetUIDGIDWithCaps(uid_t uid, gid_t gid, unsigned long long capBits,
> goto cleanup;
>
> /* Tell it we are done keeping capabilities */
> - if (need_prctl && prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0)) {
> + if (prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0)) {
> virReportSystemError(errno, "%s",
> _("prctl failed to reset KEEPCAPS"));
> goto cleanup;
> }
>
> + /* Set bounding set while we have CAP_SETPCAP. Unfortunately we cannot
> + * do this if we failed to get the capability above, so ignore the
> + * return value.
> + */
> + capng_apply(CAPNG_SELECT_BOUNDS);
...and then separately limiting bounds, but still while having an
overlarge set.
> +
> /* Drop the caps that allow setuid/gid (unless they were requested) */
> if (need_setgid)
> capng_update(CAPNG_DROP, CAPNG_EFFECTIVE|CAPNG_PERMITTED, CAP_SETGID);
> @@ -3078,7 +3082,7 @@ virSetUIDGIDWithCaps(uid_t uid, gid_t gid, unsigned long long capBits,
> if (need_setpcap)
> capng_update(CAPNG_DROP, CAPNG_EFFECTIVE|CAPNG_PERMITTED, CAP_SETPCAP);
Here, the set is now pruned to size...
>
> - if (need_prctl && ((capng_ret = capng_apply(CAPNG_SELECT_BOTH)) < 0)) {
> + if (((capng_ret = capng_apply(CAPNG_SELECT_CAPS)) < 0)) {
...but you are now only limiting caps, not the bounding set. Is that
correct?
Does this need to be considered for 1.0.4, or can we delay it to
post-release?
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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