[LTP] [PATCH] open|creat: skip S_ISGID check on files created by non-group members

[Cyril Hrubis]

Hi!
> 0fa3ecd87848 ("Fix up non-directory creation in SGID directories")
> fixes problem described in CVE-2018-13405. This commit is getting
> backported to older streams as well.
> 
> This patch removes S_ISGID check for files created by non-group members
> in LTP tests creat08 and open10.

Looks good, acked.

> Once 0fa3ecd87848 will be in non-rc kernel, we could add a new test
> for this CVE that would be limited to 4.18+ kernels.

Given that this is CVE we may as well go a little bit further and write
a test that will fail even on older kernels.

> Signed-off-by: Jan Stancek <jstancek@redhat.com>
> ---
>  testcases/kernel/syscalls/creat/creat08.c | 13 ++++++-------
>  testcases/kernel/syscalls/open/open10.c   | 12 +++++-------
>  2 files changed, 11 insertions(+), 14 deletions(-)
> 
> diff --git a/testcases/kernel/syscalls/creat/creat08.c b/testcases/kernel/syscalls/creat/creat08.c
> index 50f2b39931b8..d22558ac3c53 100644
> --- a/testcases/kernel/syscalls/creat/creat08.c
> +++ b/testcases/kernel/syscalls/creat/creat08.c
> @@ -361,13 +361,12 @@ int main(int ac, char **av)
>  			local_flag = FAILED;
>  		}
>  
> -		/* Verify modes */
> -		if (!(buf.st_mode & S_ISGID)) {
> -			tst_resm(TFAIL,
> -				 "%s: Incorrect modes, setgid bit should be set",
> -				 setgid_B);
> -			local_flag = FAILED;
> -		}
> +		/*
> +		 * Skip S_ISGID check
> +		 * 0fa3ecd87848 ("Fix up non-directory creation in SGID directories")
> +		 * clears S_ISGID for files created by non-group members
> +		 */
> +
>  		close(fd);
>  
>  		if (local_flag == PASSED) {
> diff --git a/testcases/kernel/syscalls/open/open10.c b/testcases/kernel/syscalls/open/open10.c
> index 613f2288fbde..14feec9e127e 100644
> --- a/testcases/kernel/syscalls/open/open10.c
> +++ b/testcases/kernel/syscalls/open/open10.c
> @@ -345,13 +345,11 @@ int main(int ac, char *av[])
>  			local_flag = FAILED;
>  		}
>  
> -		/* Verify modes */
> -		if (!(buf.st_mode & S_ISGID)) {
> -			tst_resm(TFAIL,
> -				 "%s: Incorrect modes, setgid bit not set",
> -				 setgid_B);
> -			local_flag = FAILED;
> -		}
> +		/*
> +		 * Skip S_ISGID check
> +		 * 0fa3ecd87848 ("Fix up non-directory creation in SGID directories")
> +		 * clears S_ISGID for files created by non-group members
> +		 */
>  
>  		if (local_flag == PASSED) {
>  			tst_resm(TPASS, "Test passed in block2.");
> -- 
> 1.8.3.1
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

-- 
Cyril Hrubis
chrubis@suse.cz