Messages in this thread | | | Date | Mon, 20 Aug 2007 01:24:20 +0200 | From | Rene Herman <> | Subject | Re: group ownership of tun devices -- nonfunctional? |
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On 08/19/2007 11:42 PM, Bodo Eggert wrote:
> On Sun, 19 Aug 2007, Rene Herman wrote: > >> On 08/19/2007 06:05 PM, Bodo Eggert wrote: >> >>> IMHO the check is broken: >>> >>> + if (((tun->owner != -1 && >>> + current->euid != tun->owner) || >>> + (tun->group != -1 && >>> + current->egid != tun->group)) && >>> + !capable(CAP_NET_ADMIN)) >>> return -EPERM; >>> >>> It should be something like: >>> >>> + if (!((tun->owner == tun->owner) || >>> + (tun->group == tun->group) || >> ??? > > Argh, I edited asuming the same order of variables. Substitute > current->e{uid,gid} for one of the sides.
Okay. Just had to ask. That looked so odd...
>>> + capable(CAP_NET_ADMIN))) >>> return -EPERM; > > The intended semantics is If the user is not > * the allowed user > or > * member of the allowed group > or > * cabable of CAP_NET_ADMIN > then error out. I'm asuming
There is a short description of the desired semantics in the link that was posted:
http://lkml.org/lkml/2007/6/18/228
=== The user now is allowed to send packages if either his euid or his egid matches the one specified via tunctl (via -u or -g respecitvely). If both gid and uid are set via tunctl, both have to match. ===
Paraphrasing the original code above, it's saying:
if ((owner_is_set && does_not_match) || (group_is_set && does_not_match)) bugger_off_unless(CAP_NET_ADMIN);
or reverting the logic:
if ((owner_is_unset || does_match) && (group_is_unset || does_match)) good_to_go();
which probably matches the intention -- we're good to go only if the credentials that are set also match.
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