"Serge E. Hallyn" <serue@xxxxxxxxxx> writes:
> Quoting Eric W. Biederman (ebiederm@xxxxxxxxxxxx):
>>
>> I have take an snapshot of my development tree and placed it at.
>>
>>
>> git://git.kernel.org/pub/scm/linux/people/ebiederm/linux-2.6.33-nsfd-v5.git
>>
>>
>> >> I am going to explore a bit more. Given that nsfd is using the same
>> >> permission checks as a proc file, I think I can just make it a proc
>> >> file. Something like "/proc/<pid>/ns/net". With a little luck that
>> >> won't suck too badly.
>> >>
>> > Ah ! yes. Good idea.
>>
>> It is a hair more code to use proc files but nothing worth counting.
>>
>> Probably the biggest thing I am aware of right now in my development
>> tree is in getting uids to pass properly between unix domain sockets
>> I would up writing this cred_to_ucred function.
>>
>> Serge can you take a look and check my logic, and do you have
>> any idea of where we should place something like pid_vnr but
>> for the uid namespace?
>
> Well my first thought was user_namespace, but I'm thinking kernel/cred.c is
> the best place for it.
Thanks.
>> void cred_to_ucred(struct pid *pid, const struct cred *cred,
>> struct ucred *ucred)
>> {
>> ucred->pid = pid_vnr(pid);
>> ucred->uid = ucred->gid = -1;
>> if (cred) {
>> struct user_namespace *cred_ns = cred->user->user_ns;
>> struct user_namespace *current_ns = current_user_ns();
>> struct user_namespace *tmp;
>>
>> if (likely(cred_ns == current_ns)) {
>> ucred->uid = cred->euid;
>> ucred->gid = cred->egid;
>> } else {
>> /* Is cred in a child user namespace */
>> tmp = cred_ns;
>> do {
>> tmp = tmp->creator->user_ns;
>> if (tmp == current_ns) {
>
> Hmm, I think you want to catch one level up - so the creator itself
> is in current_user_ns, so
>
> do {
> if (tmp->creator->user_ns == current_ns) {
> ucred->uid = tmp->creator->uid;
> ucred->gid = tmp->creator_gid;
> return;
> }
> tmp = tmp->creator->user_ns;
> } while (tmp != &init_user_ns);
Good catch.
>> ucred->uid = tmp->creator->uid;
>> ucred->gid = overflowgid;
>
> should we start recording a user_ns->creator_gid
> instead?
I had a similar question. Possibly we can just grab the creators cred.
>> return;
>> }
>> } while (tmp != &init_user_ns);
>>
>> /* Is cred the creator of my user namespace,
>> * or the creator of one of it's parents?
>> */
>> for( tmp = current_ns; tmp != &init_user_ns;
>> tmp = tmp->creator->user_ns) {
>> if (cred->user == tmp->creator) {
>> ucred->uid = 0;
>> ucred->gid = 0;
>> return;
>> }
>> }
>
> That looks right.
>
>> /* No user namespace relationship so no mapping */
>> ucred->uid = overflowuid;
>> ucred->gid = overflowgid;
>> }
>> }
>> }
Eric
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