On 05/10/2013 07:29 PM, Chen Gang wrote:
> On 05/10/2013 05:50 PM, Chen Gang wrote:
>> On 05/10/2013 10:08 AM, Chen Gang wrote:
>>> On 05/10/2013 04:11 AM, Andrew Morton wrote:
>>>>>>>>> For me, after 'rule->tree = NULL', all things seems fine !!
>>>>> Well, what was wrong before? Is there some user-triggerable
>>>>> misbehaviour which you observed? If so, please describe it.
>>>>>
>>>>>
>>>>>
>>
>
If we force 'postponed' to be NUL, and still use the original test plan:
>> Test plan:
>> code preparation:
>> define a flag varaible.
>> wait the flag to be true, before lock 'audit_filter_mutex' again. in
>> audit_add_tree_rule()
>> when evict_trunc() finish, set the flag true.
>> firstly start: 'rm -rvf /tmp/gchen/linux-next'
>> then start: 'audit -w /tmp/gchen/linux-next/drivers/char'
>> (notice the order should not be changed, or all system call will be
>> locked)
If not set 'rule->tree = NULL', it will cause issue: kernel will die !!.
But if set 'rule->tree = NULL', all things seems OK, and the output log
is just what we expected.
---------------------------test result begin--------------------------------
task_struct ptr: function(): action:
related value:
[ 627.422698] gchen_tag: ffff88009b8787a0, audit_init_entry(): create entry:
ffff88008bc75600
[ 627.422712] gchen_tag: ffff88009b8787a0, audit_receive_filter(): before
call, type: 1011
[ 627.422718] gchen_tag: ffff88009b8787a0, audit_add_tree_rule(): enter
function
[ 627.422822] ida_remove called for id=0 which is not allocated.
[ 627.422834] gchen_tag: ffff88009b8787a0, audit_add_tree_rule(): begin
waiting 100...., rule: ffff88008bc75620
[ 639.421114] gchen_tag: ffff88009b878000, evict_chunk(): enter function
postponed: (null)
[ 639.421197] gchen_tag: ffff88009b878000, evict_chunk(): kill_rull postponed:
(null)
[ 639.421209] gchen_tag: ffff88009b878000, kill_rules(): list_del_init, rule:
ffff88008bc75620, tree: (null)
[ 639.421213] gchen_tag: ffff88009b878000, evict_chunk(): audit_schedule_prune
postponed: (null)
[ 639.421274] gchen_tag: ffff88009b878000, evict_chunk(): set audit_test_count
= true, postponed: (null)
[ 639.421282] gchen_tag: ffff88009b8787a0, audit_add_tree_rule(): end waiting,
rule: ffff88008bc75620
[ 639.421289] gchen_tag: ffff88009b8787a0, audit_add_tree_rule(): list empty
for rule->rlist and return fail: ffff88008bc75620
[ 639.421364] gchen_tag: ffff88009b8787a0, audit_receive_filter(): after call
for failure, type: 1011
[ 639.421369] gchen_tag: ffff88009b8787a0, audit_free_rule(): remove entry:
ffff88008bc75600
---------------------------test result end----------------------------------
Next, I will try to find a test case to let 'postponed' to NUL by
itself (not with hard coded by force), then test it again :-).
Thanks.
> Oh, sorry again, the 'postponed' in evict_chunk() still has a chance to
> be NULL: firstly, 'audit_context->in_syscall' also checked in
> audit_killed_trees(), and also not all tasks are generated by do_fork().
>
> But really, for most cases, the 'postponed' is not NULL, so my test case
> can not cause issue.
>
> Currently, I just force 'postponed' to be NULL to see the test result... :-)
>
> It seems my original fix is still useful ! ;-)
>
> Thanks.
>
>> Oh, sorry, after have a test, the original code is no issue (it is my
>> fault).
>>
>> When the deleting work flow call evict_chunk(), I assume that the
>> 'postponed' can be NULL (at least, in some condition, it can), so
>> kill_rules() can be called directly. But in fact, 'postponed' will
>> never be NULL:
>>
>> audit_tree depend on CONFIG_AUDIT_TREE which depend on CONFIG_AUDITSYSCALL.
>> if CONFIG_AUDITSYSCALL defined.
>> do_fork() -> copy_process() -> audit_alloc() -> alloc 'audit_context'.
>> so the audit_killed_tree() will return valid pointer to 'postponed'.
>>
>> although already have quite a few code for 'postponed == NULL', they are
>> really useless now.
>>
>> I also read all other work flow which related with kill_rule(), I can
>> not find any of them can lead audit_add_tree_rule() to cause issue: all
>> work flow related with kill_rule() are protected by audit_cmd_mutex now.
>>
>>
>> Test plan:
>> code preparation:
>> define a flag varaible.
>> wait the flag to be true, before lock 'audit_filter_mutex' again. in
>> audit_add_tree_rule()
>> when evict_trunc() finish, set the flag true.
>> firstly start: 'rm -rvf /tmp/gchen/linux-next'
>> then start: 'audit -w /tmp/gchen/linux-next/drivers/char'
>> (notice the order should not be changed, or all system call will be
>> locked)
>>
>> Test result:
>> the evict_chunk() will not call kill_rule() directly, so no issues.
>> the output sample result like this: ('printk' the related information)
>>
>> ---------------------------sample begin-----------------------------
>>
>> [ 85.455891] gchen_tag: ffff880099f0ddc0, audit_init_entry(): create
>> entry: ffff880097ca2800
>> [ 85.455900] gchen_tag: ffff880099f0ddc0, audit_receive_filter(): before
>> call, type: 1011
>> [ 85.455903] gchen_tag: ffff880099f0ddc0, audit_add_tree_rule(): enter
>> function
>> [ 85.455927] ida_remove called for id=0 which is not allocated.
>> [ 85.455935] gchen_tag: ffff880099f0ddc0, audit_add_tree_rule(): begin
>> waiting 100...., rule: ffff880097ca2820
>> [ 91.425947] gchen_tag: ffff880097995dc0, fsnotify_clear_marks_by_inode():
>> set audit_test_count = true
>> [ 91.425960] gchen_tag: ffff880099f0ddc0, audit_add_tree_rule(): end
>> waiting, rule: ffff880097ca2820
>> [ 91.426055] gchen_tag: ffff880099f0ddc0, audit_receive_filter(): after
>> call for succeed, type: 1011
>> [ 91.426558] gchen_tag: ffff880097995dc0, kill_rules(): list_del_init,
>> rule: ffff880097ca2820, tree: ffff880099dfff00
>> [ 91.426564] gchen_tag: ffff880097995dc0, kill_rules(): remove entry:
>> ffff880097ca2800
>> [ 91.431023] gchen_tag: ffff880097995dc0, audit_free_rule(): remove entry:
>> ffff880097ca2800
>>
>> ---------------------------sample end-------------------------------
>>
>>
>> Now, my original fix makes the related code consistent, but the related
>> code maybe be useless now (if what I said is true, in audit, quite a
>> few of code are useless for this reason).
>>
>> I can not be sure whether these useless code will be used, in the
>> future (whether let AUDIT_TREE and AUDIT_WATCH independent on
>> AUDIT_SYSCALL in the future).
>>
>> If it will be used in the future, my fix is useful too, else we'd
>> better to delete the related useless code.
>>
>> Thanks.
>>
>>> I think, it will cause issue (randomly): if when we are using auditctl
>>> to add rule to monitor one file, and at the same time, the other user is
>>> just deleting this file.
>>>
>>> I guess, it is why original code need 'if (list_empty(&rule->rlist))'
>>> after lock 'audit_filter_mutex' again.
>>>
>>> Currently, I am just testing for it (and should give a test), and I will
>>> send the test plan and test result within this week (2013-05-12).
>>>
>>>
>>> Thanks.
>>>
>>> -- Chen Gang Asianux Corporation
>>>
>>
>>
>
>
--
Chen Gang
Asianux Corporation
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