Re: [LTP] Issue observed with chmod05, fchmod05 test cases

[Wei Y. <yj...@cn...>]

Sharyathi Nagesh wrote:
> Hi
>   I am observing this anomaly with these 2 test cases chmod05.c and
> fchmod05.c.
> These 2 test cases are written to test the POSIX standard which says:
>
>      "If the calling process is not privileged  (Linux:  does  not 
> have  the
>        CAP_FSETID  capability),  and  the group of the file does not
> match the
>        effective group ID of the process or one  of  its 
> supplementary  group
>        IDs,  the  S_ISGID  bit  will be turned off, but this will not
> cause an
>        error to be returned."
>
>
> So the test case will try to setup a file in which the GID of the
> test/tmp file will be different from the effective group ID of the
> running process. But this criterion is found to be not sufficient
> condition for the clearing the S_ISGID bit of the file
>
> ------------------------------------------------------------
> Ex:
> There are 2 users nobody (uid=99, gid=99) and bin (uid=1, gid=1)
> let as assume temporary file as /tmp/zxcv
>
> Test will Pass if
>     Set UID/GID of /tmp/zxcv to            nobody->uid & nobody->GID
>     Set eUID/eGID of process to           nobody->uid & bin->GID
>
> Test will Fail if
>     Set UID/GID of /tmp/zxcv to            nobody->uid & bin->GID
>     Set eUID/eGID of process to           nobody->uid & nobody->GID
>
> I verified supplementary group IDs for both 'nobody' and 'bin' and
> they are mutually exclusive and none of the other is supplementary
> group ID of the ID being tested
> ------------------------------------------------------------
>
> Should we treat this as Test case issue or kernel bug?

The different of 'nobody' and 'bin' is bin->GID has the CAP_FSETID 
capability, but nobody->GID has not, I think.

Regards.