File change notification along with user

[rohan puri]

On Wed, Oct 12, 2011 at 12:17 PM, V.Ravikumar
<ravikumar.vallabhu at gmail.com>wrote:

>
> On Wed, Oct 12, 2011 at 12:04 PM, rohan puri <rohan.puri15 at gmail.com>wrote:
>
>>
>>
>> On Wed, Oct 12, 2011 at 10:50 AM, V.Ravikumar <
>> ravikumar.vallabhu at gmail.com> wrote:
>>
>>> Other than fanotify , I can achieve my requirement through a
>>> driver/module. If this can be achieved through a driver/module please
>>> provide me inputs to start.
>>>
>>> Thanks,
>>> Ravi
>>>
>>> On Wed, Sep 21, 2011 at 10:27 AM, rohan puri <rohan.puri15 at gmail.com>wrote:
>>>
>>>>
>>>>
>>>> On Wed, Sep 21, 2011 at 10:03 AM, V.Ravikumar <
>>>> ravikumar.vallabhu at gmail.com> wrote:
>>>>
>>>>> Hi all,
>>>>>
>>>>> Is it possible to write a module/driver which notifies file/directory
>>>>> change asynchronously along with user name(or with uid) who modified it.
>>>>>
>>>>> inotify will do change notification but it will not provide uid who
>>>>> modified/created the file.
>>>>>
>>>>> audit and inotify combination can work, but I'm looking for a better
>>>>> option than this.
>>>>>
>>>>> Please help me.
>>>>>
>>>>> Thanks,
>>>>> Ravi
>>>>>
>>>>> _______________________________________________
>>>>> Kernelnewbies mailing list
>>>>> Kernelnewbies at kernelnewbies.org
>>>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>>>>>
>>>>> You can have a look at fanotify.
>>>>
>>>> Refer http://lwn.net/Articles/339253/
>>>>
>>>> Regards,
>>>> Rohan Puri
>>>>
>>>
>>> Hi Ravi,
>>
>> See, first of all if you want to notify file/dir change you need to the
>> control after the invocation of that i_ops or f_ops. So there are two ways
>> in which you can do : -
>>
>> 1. Easy & recommended : -
>>
>> Write a stackable file system module. The aim of this module will be to
>> intercept vfs-calls on files/dirs & then call the underlying file systems
>> specific operations. Now after completion of this operation, you would
>> generate the change event here which will be used to notify.
>>
>>
>> Note : - stackable file system research work was done by Professor *Erez
>> Zadok.
>>
>> *
>> refer ecryptfs for an example.
>>
>
>     This is more helpful for me.
>
>>
>> 2. Complex & not recommended : -
>>
>> Instead of writing a stackable file system, you hook the mount sys call to
>> get the control of the fs related structs. Then replace the original i_ops
>> and f_ops pointer with your own defined ops. save the originals somewhere.
>> Then when from user-space when some change operation is called, internally
>> your ops will be called and now you call the original stored one and
>> contruct the notification events
>>
>>
>  Even I've this in my mind. As it is not  recommended,I had dropped this
> choice
>
> 3. See if the module making use of LSM infrastructure will be able to do
>> this or not.
>>
>> Regards,
>> Rohan Puri
>>
> Hi Rohan
>
> Thank you for your valuable inputs. I will through the ecryptfs
>
> Thanks
> Ravi
>

Hi Ravi,

Good :). One more thing about that first approach, that stackable file
system has to be mounted on the top-level directory, for which (sub-dirs and
files) you need the notifications. This acts as the stacking trigger point.

Was just keen to know, where are you requiring it?

Regards,
Rohan Puri
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