Re: Kernel error: SELinux: Invalid class 0

[Stephen Smalley <sds@tycho.nsa.gov>]

On 06/15/2015 12:41 PM, Stephen Smalley wrote:
> On 06/12/2015 01:48 PM, Tim Shearer wrote:
>> Hi all,
>>
>>  
>>
>> Environment: CentOS 7, with either stock 3.10 kernel, or custom 3.19 kernel.
>>
>>  
>>
>> I’m getting a AVC denial message in the audit logs that corresponds to
>> the opening of a TIPC socket (AF_TIPC). The denial is seems valid, and
>> is triggered by a custom C++ application that hasn’t yet been assigned
>> an appropriate security context. The problem I’m having is that the AVC
>> message is garbled (non-ASCII data in the denied and tclass fields),
>> which makes it difficult to assemble a new policy:
>>
>>  
>>
>> ----
>>
>> type=AVC msg=audit(1434126658.487:34500): avc:  denied  {
>> *garbage_characters* } for  pid=292 comm="kworker/u16:5"
>> scontext=system_u:system_r:kernel_t:s0
>> tcontext=system_u:object_r:unlabeled_t:s0 tclass=*garbage_characters*
>> permissive=0
>>
>> ----
>>
>>  
>>
>> This corresponds to a kernel error that shows up in the debuglog:
>>
>> SELinux:  Invalid class 0
> 
> This suggests that the tipc kernel module is creating a socket in some
> manner without initializing its security state.
> 
> Can you provide a reproducer program that triggers the error?

Looks to me as if tipc_accept() never calls sock_graft() or
security_sk_clone() so it will never initialize the security state of
the new sock.  Kernel bug.