linux-kernel - Re: [PATCH v3 02/15] exec: Rename bprm->cred_prepared to called_set

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Date:   Tue, 18 Jul 2017 21:40:03 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        David Howells <dhowells@...hat.com>,
        John Johansen <john.johansen@...onical.com>,
        Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        Casey Schaufler <casey@...aufler-ca.com>,
        James Morris <james.l.morris@...cle.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        LSM List <linux-security-module@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 02/15] exec: Rename bprm->cred_prepared to called_set_creds

On Tue, Jul 18, 2017 at 6:06 PM, Andy Lutomirski <luto@...nel.org> wrote:
> On Tue, Jul 18, 2017 at 3:25 PM, Kees Cook <keescook@...omium.org> wrote:
>> The cred_prepared bprm flag has a misleading name. It has nothing to do
>> with the bprm_prepare_cred hook, and actually tracks if bprm_set_creds has
>> been called. Rename this flag and improve its comment.
>>
>> Cc: David Howells <dhowells@...hat.com>
>> Cc: John Johansen <john.johansen@...onical.com>
>> Cc: Paul Moore <paul@...l-moore.com>
>> Cc: Stephen Smalley <sds@...ho.nsa.gov>
>> Cc: Casey Schaufler <casey@...aufler-ca.com>
>> Cc: James Morris <james.l.morris@...cle.com>
>> Signed-off-by: Kees Cook <keescook@...omium.org>
>> ---
>>  fs/binfmt_flat.c           | 2 +-
>>  fs/exec.c                  | 2 +-
>>  include/linux/binfmts.h    | 8 ++++++--
>>  security/apparmor/domain.c | 2 +-
>>  security/selinux/hooks.c   | 2 +-
>>  security/smack/smack_lsm.c | 2 +-
>>  security/tomoyo/tomoyo.c   | 2 +-
>>  7 files changed, 12 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
>> index 2edcefc0a294..a722530cc468 100644
>> --- a/fs/binfmt_flat.c
>> +++ b/fs/binfmt_flat.c
>> @@ -885,7 +885,7 @@ static int load_flat_shared_library(int id, struct lib_info *libs)
>>          * as we're past the point of no return and are dealing with shared
>>          * libraries.
>>          */
>> -       bprm.cred_prepared = 1;
>> +       bprm.called_set_creds = 1;
>
> WTF is this?  It's not, strictly speaking, a bug in this patch, but
> it's nonsensical.  Is it fixed (presuably deleted) later?

binfmt_flat looks crazy, but I haven't seen any distros that enable it.

> Otherwise looks good.

Thanks!

-Kees

-- 
Kees Cook
Pixel Security