"Sugar, David" <dsugar@xxxxxxxxxx> writes:
> On 1/6/19 7:40 AM, Dominick Grift wrote:
>> "Sugar, David" <dsugar@xxxxxxxxxx> writes:
>>
>>> The display manager lightdm (and I think gdm) start a dbus binary.
>>>
>>> This adds (and uses) new interface dbus_exec to start dbus in the xdm domain.
>>>
>>> type=AVC msg=audit(1544626796.378:201): avc: denied { execute } for pid=9973 comm="dbus-launch" name="dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>>> type=AVC msg=audit(1544626796.378:201): avc: denied { read open } for pid=9973 comm="dbus-launch" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>>> type=AVC msg=audit(1544626796.378:201): avc: denied { execute_no_trans } for pid=9973 comm="dbus-launch" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>>> type=AVC msg=audit(1544626796.378:201): avc: denied { map } for pid=9973 comm="dbus-daemon" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>>> type=AVC msg=audit(1546551459.112:208): avc: denied { getcap } for pid=6275 comm="dbus-daemon" scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tclass=process permissive=1
>>>
>>> Signed-off-by: Dave Sugar <dsugar@xxxxxxxxxx>
>>> ---
>>> policy/modules/services/dbus.if | 21 +++++++++++++++++++++
>>> policy/modules/services/xserver.te | 1 +
>>> 2 files changed, 22 insertions(+)
>>>
>>> diff --git a/policy/modules/services/dbus.if b/policy/modules/services/dbus.if
>>> index ef829e30..d0eec745 100644
>>> --- a/policy/modules/services/dbus.if
>>> +++ b/policy/modules/services/dbus.if
>>> @@ -17,6 +17,27 @@ interface(`dbus_stub',`
>>> ')
>>> ')
>>>
>>> +########################################
>>> +## <summary>
>>> +## Execute dbus in the caller domain.
>>> +## </summary>
>>> +## <param name="domain">
>>> +## <summary>
>>> +## Domain allowed access.
>>> +## </summary>
>>> +## </param>
>>> +#
>>> +interface(`dbus_exec',`
>>> + gen_require(`
>>> + type dbusd_exec_t;
>>> + ')
>>> +
>>> + corecmd_search_bin($1)
>>> + can_exec($1, dbusd_exec_t)
>>> +
>>> + allow $1 self:process getcap;
>> I would not enclose the getcap rule here. For example I do not believe
>> you need that permission to be able to `dbus-daemon --version`. Instead I
>> would add that rule to xserver.te:
>>
>> allow xdm_t self:process getcap;
>
> I did it this way due to the fact that it is dbus-daemon needing the
> getcap permission not lightdm. So other processes that use the
> dbus_exec interface will also need this permission. I'm happy separate
> just worry it won't be clear why getcap will be added in several places
> due to this.
>
`dbus-daemon --version` does not seem to require getcap
executing dbus potentially requires many permissions but that does not
mean that we should add these permissions to dbus_exec()
>>> +')
>>> +
>>> ########################################
>>> ## <summary>
>>> ## Role access for dbus.
>>> diff --git a/policy/modules/services/xserver.te b/policy/modules/services/xserver.te
>>> index fa7ce88e..cc717e7f 100644
>>> --- a/policy/modules/services/xserver.te
>>> +++ b/policy/modules/services/xserver.te
>>> @@ -566,6 +566,7 @@ optional_policy(`
>>> ')
>>>
>>> optional_policy(`
>>> + dbus_exec(xdm_t)
>>> dbus_system_bus_client(xdm_t)
>>> dbus_connect_system_bus(xdm_t)
--
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Dominick Grift
