Re: [LTP] Requested user & group [was: Re: [linux-test-project/ltp] Release 20210927 - LTP 20210927]

[Petr Vorel <petr.vorel@gmail.com>]

> On 10/4/21 11:02 AM, Petr Vorel wrote:
> > I'm sorry, I was wrong, I meant GID "nogroup". Looking into the source, there is
> > no "AID_NOGROUP", thus we need to keep using GID "daemon" for AOSP instead
> > "nogroup". IMHO instead SAFE_GETGRNAM_FALLBACK() this should be set somewhere in
> > the library, so that it's for all tests.

> Hi Petr, I've created an issue internally to track adding 'nogroup'. It may
> be a little while before it goes in though.

Hi Steve, Martin, Sandeep, Cyril,

@Steve, I'm very sorry, I didn't interpret the changelog correctly. As Martin
notified me, since his patchset [1][2] merged as dc84a2490~..7d4fdf3bb the only
groups queried by name are "users" and "daemon" (these in
SAFE_GETGRNAM_FALLBACK()). He actually removed all references to "nobody" and
"nogroup" in the patchset, tests now use tst_get_gids(), getgid() or get the
primary group through getpwnam("nobody"). Thus there is no need to create group
"nogroup", please close that internal aosp ticket.

Looking into tst_get_{g,u}ids() implementation it "The function will fill the
remaining (size-start) entries with unique UID/GID values.". But the problem is
that it expect there are no gaps in UID/GID values. While this is true for
traditional linux distros (not sure about embedded distros), it's definitely not
true for aosp, see AID_ definitions in libcutils source [1].

e.g. tst_get_gids(test_groups, 0, 2) (from setregid03.c) returns GID 1 and 2.
But on aosp getpwuid(1) and getpwuid(2) fails (I verified that by running code
on aosp 8). There is GID AID_DAEMON 1 ("daemon") and AID_BIN 2 ("bin"), which
has been added for aosp 9 (8e8648463d7 ("libcutils: Add "daemon" and "bin" users
for testing only")) and IMHO no use of tst_get_gids() so far does require higher
GID that 2, but once higher ID is needed it will break (and even adding GID
"nobody" would help much).

Fix would be to actually try to run getpwuid(with expected id) until
it's found, but next GID for aosp is AID_SYSTEM 1000, thus it wouldn't scale.
But it would work with aosp < 9 (not sure if anybody cares for old aosp).

Back to tests which use SAFE_GETGRNAM_FALLBACK() (used in chmod07.c, fchmod02.c).
With current implementation, it'd be possible to replace it with tst_get_gids().

Kind regards,
Petr

[1] https://cs.android.com/android/platform/superproject/+/master:system/core/libcutils/include/private/android_filesystem_config.h;l=43?q=AID_

> cheers,
> Steve

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