[LTP] [PATCH] shmget02: fix EPERM test when RLIMIT_MEMLOCK is large enough

[xuyang2018.jy@fujitsu.com <xuyang2018.jy@fujitsu.com>]

Hi Thadeu
> shmget(..., SHM_HUGETLB) will not fail with EPERM if there is enough space
> for RLIMIT_MEMLOCK. If the limit is 0, it will fail with EPERM as expected
> when a not enough privileged user calls it.
>
> Set RLIMIT_MEMLOCK to 0 for all calls, as this is the only one which will
> fail because of that limit, unless we are talking about very old kernels
> (before 2.6.9).
>
> Fixes: 4dc493b44a85 ("syscalls/shmget*: Convert into new api")
> Signed-off-by: Thadeu Lima de Souza Cascardo<cascardo@canonical.com>
Thanks for the fix!
Reviewed-by: Yang Xu <xuyang2018.jy@fujitsu.com>

just a small nit: Since a child process created via fork(2) inherits its 
parent's resource limits. I prefer to move it to setup function, so we 
don't need to set it in each sub case.

Best Regards
Yang Xu
> ---
>   testcases/kernel/syscalls/ipc/shmget/shmget02.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/testcases/kernel/syscalls/ipc/shmget/shmget02.c b/testcases/kernel/syscalls/ipc/shmget/shmget02.c
> index 6be8d8157999..8857207cfd3d 100644
> --- a/testcases/kernel/syscalls/ipc/shmget/shmget02.c
> +++ b/testcases/kernel/syscalls/ipc/shmget/shmget02.c
> @@ -64,6 +64,7 @@ static void do_test(unsigned int n)
>   {
>   	struct tcase *tc =&tcases[n];
>   	pid_t pid;
> +	struct rlimit rl = { 0, 0 };
>
>   	if (tc->exp_user == 0&&  tc->exp_group == 0) {
>   		TST_EXP_FAIL2(shmget(*tc->shmkey, tc->size, tc->flags), tc->exp_err,
> @@ -78,6 +79,7 @@ static void do_test(unsigned int n)
>   			SAFE_SETGID(pw->pw_gid);
>   		}
>   		SAFE_SETUID(pw->pw_uid);
> +		SAFE_SETRLIMIT(RLIMIT_MEMLOCK,&rl);
>   		TST_EXP_FAIL2(shmget(*tc->shmkey, tc->size, tc->flags), tc->exp_err,
>   			"shmget(%i, %lu, %i)", *tc->shmkey, tc->size, tc->flags);
>   		exit(0);