[LTP] [PATCH v2 09/13] syscalls/mount03: Copy setuid_test to execute instead of 'TEST FILE'

[Cyril Hrubis]

Hi!
> > What is the exact error here? I guess that the file does not have
> > execute bit set and that check kicks in first?
> 
> I have a feeling that we might be cross-talking on this one.
> 
> IIUC, the intention for the test is to try and execute the binary
> setuid_test (built from setuid_test.c). Instead, the test creates a file
> named "setuid_test" at the mount location and writes "TEST FILE" into
> it.
> 
>        snprintf(file, PATH_MAX, "%ssetuid_test", path_name);
>        SAFE_FILE_PRINTF(cleanup, file, "TEST FILE");
> 
> It then tries to execute this file containing the text string which
> fails with the message -
> 
> /bin/sh: 0: Can't open /tmp/mouc0EQuB/mntpoint/setuid_test
> mount03     6  TPASS  :  mount(2) passed with rwflag = 2
> 
> The patch copies the file setuid_test into the mounted filesystem at
> which point we no longer get the "/bin/sh:" message.

Ah, right, I was under an impression that suid programs cannot be
executed on MS_NOSUID mounted FS. But after consulting mount() manual
page that was true for ancient kernels before 2.4 and the suid bits are
simply ignored in this case on newer kernels.

So yes we need to execute a helper that tries to set privileged uid.

The idea of this patch is correct then, but we need to clean up a bit.

First of all all binary helpers should start with the prefix of the test
that uses them, so in this case the helper should be renamed to
mount03_setuid.c, secondly you are supposed to use the
TST_RESOURCE_COPY() macro instead of the function itself and it should
be done once in the test setup as well as the code that sets the actual
setuid bit.

-- 
Cyril Hrubis
chrubis@suse.cz