Home » Mailing lists » Devel » userns: targeted capabilities v5
Re: User namespaces and keys [message #41861 is a reply to message #41856] |
Wed, 23 February 2011 19:24 |
Casey Schaufler
Messages: 6 Registered: November 2007
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Junior Member |
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On 2/23/2011 7:53 AM, Serge E. Hallyn wrote:
> Quoting Eric W. Biederman (ebiederm@xmission.com):
>> David Howells <dhowells@redhat.com> writes:
>>
>>> Serge E. Hallyn <serge@hallyn.com> wrote:
>>>
>>>>> I guess we need to look at how to mix keys and namespaces again.
>>>> From strictly kernel pov, at the moment, keys are strictly usable only
>>>> by the user in your own user namespace.
>>> I'm not sure that's currently completely true. Key quota maintenance is
>>> namespaced, and the key's owner UID/GID belong to that namespace, so that's
>>> okay, but:
>>>
>>> (*) key_task_permission() does not distinguish UIDs and GIDs from different
>>> namespaces.
>>>
>>> (*) A key can be referred to by its serial number, no matter whose namespace
>>> it is in, and will yield up its given UID/GID, even if these aren't
>>> actually meaningful in your namespace.
>>>
>>> This means request_key() can successfully upcall at the moment.
>>>
>>> I wonder if I should make the following changes:
>>>
>>> (1) If the key and the accessor are in different user namespaces, then skip
>>> the UID and GID comparisons in key_task_permission(). That means that to
>>> be able to access the key you'd have to possess the key and the key would
>>> have to grant you Possessor access, or the key would have to grant you
>>> Other access.
>>>
>>> (2) If the key and someone viewing the key description are in different
>>> namespaces, then indicate that the UID and the GID are -1, irrespective of
>>> the actual values.
>>>
>>> (3) When an upcall is attempting to instantiate a key, it is allowed to access
>>> the keys of requestor using the requestor's credentials (UID, GID, groups,
>>> security label). Ensure that this will be done in the requestor's user
>>> namespace.
>>>
>>> Nothing should need to be done here, since search_process_keyrings()
>>> switches to the requestor's creds.
>>>
>>> Oh, and are security labels user-namespaced?
>> Not at this time. The user namespace as currently merged is little more
>> than a place holder for a proper implementation. Serge is busily
>> fleshing out that proper implementation.
>>
>> Until we reach the point where all checks that have historically been
>> "if (uid1 == uid2)" become "if ((uidns1 == uidns2) && (uid1 == uid2))"
>> there will be problems.
>>
>> The security labels and probably lsm's in general need to be per user
>> namespace but we simply have not gotten that far. For the short term I
>> will be happy when we get a minimally usable user namespace.
> Note also that when Eric brought this up at the LSM mini-conf two or three
> years ago, there was pretty general, strong objection to the idea.
>
> Like Eric says, I think that'll have to wait. In the meantime, isolating
> user namespace sandboxes (or containers) using simple LSM configurations
> is a very good idea.
I confess that I remain less well educated on namespaces than
I probably should be, but with what I do know it seems that the
relationships between user namespaces and LSMs are bound to be
strained from the beginning. Some LSMs (SELinux and Smack) are
providing similar sandbox capabilities to what you get from user
namespaces, but from different directions and with different
use cases.
> -serge
> --
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userns: targeted capabilities v5
By: serge on Thu, 17 February 2011 15:02
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[PATCH 2/9] security: Make capabilities relative to the user namespace.
By: serge on Thu, 17 February 2011 15:03
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Re: [PATCH 2/9] security: Make capabilities relative to the user namespace.
By: ebiederm on Fri, 18 February 2011 03:46
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Re: [PATCH 2/9] security: Make capabilities relative to the user namespace.
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Re: [PATCH 2/9] security: Make capabilities relative to the user namespace.
By: akpm on Fri, 18 February 2011 23:59
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Re: [PATCH 2/9] security: Make capabilities relative to the user namespace.
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Re: [PATCH 2/9] security: Make capabilities relative to the user namespace.
By: serge on Wed, 23 February 2011 13:43
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Re: [PATCH 2/9] security: Make capabilities relative to the user namespace.
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Re: [PATCH 2/9] security: Make capabilities relative to the user namespace.
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[PATCH 9/9] userns: check user namespace for task->file uid equivalence checks
By: serge on Thu, 17 February 2011 15:04
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Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks
By: ebiederm on Fri, 18 February 2011 01:29
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Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks
By: akpm on Fri, 18 February 2011 23:59
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Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks
By: serge on Thu, 24 February 2011 03:24
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Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks
By: akpm on Thu, 24 February 2011 05:08
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Re: [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks
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[PATCH 7/9] add a user namespace owner of ipc ns
By: serge on Thu, 17 February 2011 15:03
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Re: [PATCH 7/9] add a user namespace owner of ipc ns
By: ebiederm on Fri, 18 February 2011 03:19
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Re: [PATCH 7/9] add a user namespace owner of ipc ns
By: akpm on Fri, 18 February 2011 23:59
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Re: [PATCH 7/9] add a user namespace owner of ipc ns
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[PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace
By: serge on Thu, 17 February 2011 15:02
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Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace
By: ebiederm on Fri, 18 February 2011 03:31
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Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace
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Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace
By: akpm on Fri, 18 February 2011 23:59
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Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace
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Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace
By: ebiederm on Wed, 23 February 2011 21:21
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Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace
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Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace
By: ebiederm on Wed, 23 February 2011 23:54
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[PATCH 3/9] allow sethostname in a container
By: serge on Thu, 17 February 2011 15:03
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Re: [PATCH 3/9] allow sethostname in a container
By: ebiederm on Fri, 18 February 2011 03:05
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Re: [PATCH 3/9] allow sethostname in a container
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[PATCH 4/9] allow killing tasks in your own or child userns
By: serge on Thu, 17 February 2011 15:03
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Re: [PATCH 4/9] allow killing tasks in your own or child userns
By: ebiederm on Fri, 18 February 2011 03:00
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Re: [PATCH 4/9] allow killing tasks in your own or child userns
By: akpm on Fri, 18 February 2011 23:59
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Re: [PATCH 4/9] allow killing tasks in your own or child userns
By: serge on Thu, 24 February 2011 00:48
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Re: [PATCH 4/9] allow killing tasks in your own or child userns
By: akpm on Thu, 24 February 2011 00:54
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Re: [PATCH 4/9] allow killing tasks in your own or child userns
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[PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c
By: serge on Thu, 17 February 2011 15:03
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Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c
By: ebiederm on Fri, 18 February 2011 01:57
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Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c
By: akpm on Fri, 18 February 2011 23:59
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Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c
By: akpm on Sat, 19 February 2011 00:01
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Re: [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c
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[PATCH 5/9] Allow ptrace from non-init user namespaces
By: serge on Thu, 17 February 2011 15:03
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Re: [PATCH 5/9] Allow ptrace from non-init user namespaces
By: ebiederm on Fri, 18 February 2011 02:59
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Re: [PATCH 5/9] Allow ptrace from non-init user namespaces
By: serge on Fri, 18 February 2011 04:36
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[PATCH] userns: ptrace: incorporate feedback from Eric
By: serge on Thu, 24 February 2011 00:49
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Re: [PATCH] userns: ptrace: incorporate feedback from Eric
By: akpm on Thu, 24 February 2011 00:56
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Re: [PATCH] userns: ptrace: incorporate feedback from Eric
By: serge on Thu, 24 February 2011 03:15
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Re: [PATCH 5/9] Allow ptrace from non-init user namespaces
By: akpm on Fri, 18 February 2011 23:59
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Re: [PATCH 5/9] Allow ptrace from non-init user namespaces
By: serge on Thu, 24 February 2011 00:43
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Re: [PATCH 5/9] Allow ptrace from non-init user namespaces
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Re: [PATCH 5/9] Allow ptrace from non-init user namespaces
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Re: [PATCH 5/9] Allow ptrace from non-init user namespaces
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[PATCH 8/9] user namespaces: convert several capable() calls
By: serge on Thu, 17 February 2011 15:03
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Re: [PATCH 8/9] user namespaces: convert several capable() calls
By: ebiederm on Fri, 18 February 2011 01:51
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Re: [PATCH 8/9] user namespaces: convert several capable() calls
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Re: userns: targeted capabilities v5
By: akpm on Fri, 18 February 2011 00:21
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Re: userns: targeted capabilities v5
By: ebiederm on Fri, 18 February 2011 03:53
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Re: userns: targeted capabilities v5
By: serge on Fri, 18 February 2011 04:28
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User namespaces and keys
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Re: User namespaces and keys
By: serge on Wed, 23 February 2011 13:58
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Re: User namespaces and keys
By: ebiederm on Wed, 23 February 2011 14:46
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Re: User namespaces and keys
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Re: User namespaces and keys
By: ebiederm on Wed, 23 February 2011 15:45
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Re: User namespaces and keys
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Re: User namespaces and keys
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Re: User namespaces and keys
By: ebiederm on Wed, 23 February 2011 20:55
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Re: User namespaces and keys
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Re: User namespaces and keys
By: ebiederm on Thu, 24 February 2011 06:56
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