From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman)
To: Kirill Tkhai <ktkhai-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
Cc: Linux Containers
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Subject: Re: [PATCH] userns,pidns: Verify the userns for new pid namespaces
Date: Tue, 02 May 2017 15:39:50 -0500 [thread overview]
Message-ID: <87y3ufgfhl.fsf@xmission.com> (raw)
In-Reply-To: <fab323b8-a909-bbce-77d2-afbcd3b0452e-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org> (Kirill Tkhai's message of "Tue, 2 May 2017 13:04:37 +0300")
Kirill Tkhai <ktkhai-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org> writes:
>>> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
>>> index 2f735cbe05e8..7d8658fbabc8 100644
>>> --- a/kernel/user_namespace.c
>>> +++ b/kernel/user_namespace.c
>>> @@ -986,19 +986,25 @@ bool userns_may_setgroups(const struct user_namespace *ns)
>>> }
>>>
>>> /*
>>> - * Returns true if @ns is the same namespace as or a descendant of
>>> - * @target_ns.
>>> + * Returns true if @child is the same namespace or a descendant of
>>> + * @ancestor.
>>> */
>>> -bool current_in_userns(const struct user_namespace *target_ns)
>>> +bool in_userns(const struct user_namespace *ancestor,
>>> + const struct user_namespace *child)
>>> {
>>> - struct user_namespace *ns;
>>> - for (ns = current_user_ns(); ns; ns = ns->parent) {
>>> - if (ns == target_ns)
>>> + const struct user_namespace *ns;
>>> + for (ns = child; ns; ns = ns->parent) {
>>> + if (ns == ancestor)
>>> return true;
>>> }
>>> return false;
>>> }
>>
>> We have user_namespace::level, so it's possible to stop iterations earlier
>> and save some cpu cycles:
>>
>> for (ns = child; ns->level >= ancestor->level; ns = ns->parent)
>
> Just ">" here.
>
>> ;
>> return (ns == ancestor);
Good observation. Thank you.
Eric
next prev parent reply other threads:[~2017-05-02 20:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-27 12:32 [PATCH v3] pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy Kirill Tkhai
[not found] ` <149329634856.21195.14196911999722279118.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-04-27 15:15 ` Eric W. Biederman
[not found] ` <87mvb16fv7.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-27 15:52 ` Kirill Tkhai
[not found] ` <12a73543-79ea-4bac-7e96-6ab237534af2-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-04-27 16:07 ` Eric W. Biederman
[not found] ` <877f254yx0.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-28 9:13 ` Kirill Tkhai
[not found] ` <a9941daf-861b-453c-37b8-e95389a9959b-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-04-29 19:12 ` Eric W. Biederman
[not found] ` <8737crt4dz.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-29 19:25 ` [PATCH] userns,pidns: Verify the userns for new pid namespaces Eric W. Biederman
2017-04-29 20:53 ` Serge E. Hallyn
[not found] ` <20170429205325.GB1119-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2017-04-30 4:33 ` Eric W. Biederman
[not found] ` <87a86yseej.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-30 4:42 ` Eric W. Biederman
[not found] ` <87vapnrp7f.fsf_-_-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-05-02 10:03 ` Kirill Tkhai
2017-05-02 10:04 ` Kirill Tkhai
[not found] ` <fab323b8-a909-bbce-77d2-afbcd3b0452e-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-05-02 20:39 ` Eric W. Biederman [this message]
2017-05-02 9:53 ` [PATCH v3] pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy Kirill Tkhai
[not found] ` <d2b88252-d579-8deb-2c32-4118b8464b6b-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-05-02 21:26 ` Eric W. Biederman
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