Re: [RFC PATCH 0/1] security/keys: remove possessor verify after key

[Alexey Krasikov <alexey_krasikov@mail.ru>]

On 7/13/20 2:53 PM, Alexey Krasikov wrote:
> On 7/3/20 4:14 AM, Jarkko Sakkinen wrote:
>> On Sun, Jun 28, 2020 at 03:27:37AM +0300, Alexey Krasikov wrote:
>>> On 6/23/20 4:28 AM, Jarkko Sakkinen wrote:
>>>> On Mon, Jun 22, 2020 at 02:30:28PM +0200, Greg KH wrote:
>>>>> On Mon, Jun 22, 2020 at 12:04:29PM +0300, Alexey Krasikov wrote:
>>>>>> On 6/15/20 8:00 PM, Jarkko Sakkinen wrote:
>>>>>>> On Tue, Jun 02, 2020 at 01:30:52PM +0300, Alexey Krasikov wrote:
>>>>>>>> On Mon, June 1, 2020 at 08:34PM +300, Jarkko Sakkinen wrote:
>>>>>>>>> On Fri, May 29, 2020 at 09:00:39AM +0300, Alexey Krasikov wrote:
>>>>>>>>>> $ KEYID=$(keyctl add user john smith @u)
>>>>>>>>>> $ keyctl describe $KEYID
>>>>>>>>>> 5927639: alswrv-----v------------  1000  1000 user: john
>>>>>>>>>> $ keyctl setperm $KEYID 0x3d000000
>>>>>>>>>> $ keyctl describe $KEYID
>>>>>>>>>> 5927639: alsw-v-----v------------  1000  1000 user: john
>>>>>>>>>> $ keyctl print $KEYID
>>>>>>>>>> smith
>>>>>>>>> A keyring default permissions are 0x3f3f0000.
>>>>>>>>> A key default permissions are 0x3f010000.
>>>>>>>>>
>>>>>>>>> Because of this:
>>>>>>>>>
>>>>>>>>> $ KEYID=$(keyctl add user john smith @u)
>>>>>>>>> $ keyctl setperm $KEYID 0x3d000000
>>>>>>>>> keyctl_setperm: Permission denied
>>>>>>>>>
>>>>>>>>> Are you sure that your example is correct?
>>>>>>>>>
>>>>>>>>> /Jarkko
>>>>>>>> Yes, this example works correctly.
>>>>>>>>
>>>>>>>> Why do you think, that the current keyring and key rights
>>>>>>>>
>>>>>>>> shoukd not allow this to be done?
>>>>>>> I'm just saying that I cannot figure out your point in the cover 
>>>>>>> letter.
>>>>>>> It contains random dumps of keyctl output.
>>>>>>>
>>>>>>> Maybe a better idea would be to write a test script that 
>>>>>>> demonstrates
>>>>>>> the issue?
>>>>>>>
>>>>>>> /Jarkko
>>>>>> + alexey_krasikov@mail.ru
>>>>>>
>>>>>> Possible you may not be able to reproduce the problem because you 
>>>>>> have a
>>>>>> different version of Linux.
>>>>>>
>>>>>> I get to reproduce the problem on two systems:
>>>>>>
>>>>>> Linux 4.14.74-28+yc11.91
>>>>>>
>>>>>> and
>>>>>>
>>>>>> Linux ubuntu 4.15.0-106-generic
>>>>> Both of those are distro-specific kernels, can you reproduce this on
>>>>> 5.8-rc2 or 5.7 as released from kernel.org?
>>>> Alexey,
>>>>
>>>> A shell script containing the keyctl command chain with some 
>>>> output, and
>>>> then your version of the output when running the script would be also
>>>> very useful for better comparison.
>>>>
>>>> /Jarkko
>>> Ok. I have the following script:
>>>
>>> ---------------------------------------------------------------------------- 
>>>
>>> #!/usr/bin/sh
>>>
>>> uname -r
>>>
>>> KEYID=$(keyctl add user john smith @u)
>>> keyctl describe $KEYID
>>> keyctl setperm $KEYID 0x3d000000
>>> keyctl describe $KEYID
>>> keyctl print $KEYID
>> pam_keyinit.so should create user keyring when the login session is
>> created. If the user space stack is working correclty, you should not
>> end up to be the possessor for the user keyring.
>>
>> However, I can simulate your environment with the session keyring:
>>
>> KEYID=`keyctl add user john smith @s`
>>
>> keyctl describe $KEYID
>> keyctl setperm $KEYID 0x3d000000
>> keyctl describe $KEYID
>> keyctl print $KEYID
>>
>> And yes I do get:
>>
>> 564302411: alswrv-----v------------  1000  1000 user: john
>> 564302411: alsw-v------------------  1000  1000 user: john
>> smith
>>
>> Here's another sequence that also removes setattr:
>>
>> KEYID=`keyctl add user john smith @s`
>>
>> keyctl describe $KEYID
>> keyctl setperm $KEYID 0x08000000
>> keyctl describe $KEYID
>> keyctl print $KEYID
>>
>> 700153280: alswrv-----v------------  1000  1000 user: john
>> keyctl_describe_alloc: Permission denied
>> smith
>>
>> David, this look at least with a quick sight somewhat weird: my
>> possessor permissions are only "search", so why does reading the
>> payload succeed?
>>
>> /Jarkko
> ping
>
> /Alexey
ping, ping!!!

Hello everybody!

David, have you watched my correspondence with Jarkko?
Do you have any ideas about this strange behavior of keyctl?

/Alexey