[libvirt] [PATCH v3 1/2] security: also parse user/group names instead of just IDs for DAC labels

[Eric Blake]

On 10/05/2012 06:53 AM, Marcelo Cerri wrote:
> Just one question: do you think that makes sense for virGetUserID and
> virGetGroupID to check if a id exists when a numeric value is given?

Just because a uid hasn't been named in /etc/passwd doesn't mean it
won't be added in the future.  If the user requests a numeric value, I
think we have to respect it as a uid_t value (assuming the name lookup
failed or the leading '+' was present) regardless of whether we can do a
lookup on that uid.

One other thing - uid_t might be smaller than 'int', so we have to do
overflow checking and make sure that a user requesting 65536 doesn't end
up mapping to uid 0.

>>> ...out of security_dac.c and into src/util/util.c:virGetUserID(), so
>>> that we are consistently parsing in this manner for ALL places where we
>>> convert a string into a user id, and also so that virGetUserID will quit
>>> logging such a bogus error message when it fails to find a given id
>>> string that happens to be a valid number.
>> Ok. I'll provide a patch for this.
>>
>> I made a search in the code for virGetUserID and, other than in
>> security_dac.c, it seems to be used just for parsing user name in
>> qemu.conf.

I'm actually in favor of this change - it means qemu.conf also gains our
consistent behavior (and consistent with coreutils' chown) for handling
names vs. numbers.

-- 
Eric Blake   eblake at redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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