linux-kernel - Re: [PATCH RESEND] KEYS: fix parsing invalid pkey info string

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Message-ID: <CAHk-=wgGYebCEE-M-6Dnbn5MpC8BD8SLjgw8iPGrgy8zETrdJg@mail.gmail.com>
Date:   Mon, 17 Dec 2018 11:39:57 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     ebiggers@...nel.org, James Morris James Morris <jmorris@...ei.org>,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Peter Huewe <peterhuewe@....de>
Cc:     David Howells <dhowells@...hat.com>, keyrings@...r.kernel.org,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH RESEND] KEYS: fix parsing invalid pkey info string

On Mon, Dec 17, 2018 at 11:06 AM Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> Honestly, for being about "security", all of this code seems to be
> doing some really questionable things with all those Opt_xyz enums.

Yeah, at least security/keys/trusted.c ends up mixing that enum and
just using "int" completely randomly, and you have datablob_parse()
returning either a negative integer _or_ an "Opt_xyz" value, so having
Opt_err be -1 is doubly confusing there (it would also be "-EPERM"
depending on how you treat it).

There doesn't seem to be any _actual_ confusion (because Opt_err is
always turned into an actual real error code), but it's  just another
sign of "those enums should not be negative".

So on the whole, I think that the "Opt_err = -1" is a serious mistake,
but at least for now, ima_policy.c clearly has (bogus) code that
relies on it.

But the two cases that use "test_and_set_bit()" do not seem to have
any reason to use that -1 enum, so while we can't do the "just remove
-1" in general, I do think the proper fix is to just do it for those
two files.

Eric, mind testing a patch like that? Untested patch attached just for
completeness..

                    Linus

View attachment "patch.diff" of type "text/x-patch" (938 bytes)