From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20765C43217 for ; Wed, 16 Nov 2022 08:06:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233072AbiKPIGs (ORCPT ); Wed, 16 Nov 2022 03:06:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40244 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233051AbiKPIGp (ORCPT ); Wed, 16 Nov 2022 03:06:45 -0500 Received: from frasgout11.his.huawei.com (frasgout11.his.huawei.com [14.137.139.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84C485F52; Wed, 16 Nov 2022 00:06:42 -0800 (PST) Received: from mail02.huawei.com (unknown [172.18.147.227]) by frasgout11.his.huawei.com (SkyGuard) with ESMTP id 4NBwST5Gp5z9xFQ5; Wed, 16 Nov 2022 15:59:53 +0800 (CST) Received: from roberto-ThinkStation-P620 (unknown [10.204.63.22]) by APP2 (Coremail) with SMTP id GxC2BwAXTPjumXRjdiBrAA--.15845S2; Wed, 16 Nov 2022 09:06:18 +0100 (CET) Message-ID: <18e375adfe53f8ce5fb38a6a146ad06eaec71a5e.camel@huaweicloud.com> Subject: Re: [RFC][PATCH 1/4] lsm: Clarify documentation of vm_enough_memory hook From: Roberto Sassu To: Paul Moore Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, revest@chromium.org, jackmanb@chromium.org, jmorris@namei.org, serge@hallyn.com, bpf@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Roberto Sassu Date: Wed, 16 Nov 2022 09:06:02 +0100 In-Reply-To: References: <20221115175652.3836811-1-roberto.sassu@huaweicloud.com> <20221115175652.3836811-2-roberto.sassu@huaweicloud.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-CM-TRANSID: GxC2BwAXTPjumXRjdiBrAA--.15845S2 X-Coremail-Antispam: 1UD129KBjvJXoW7Ww4DWF4fAw18Ar4kZF4DXFb_yoW8XF43pF WkGa15Gr1v9ry8CFs2k3Wa9345Gws5Gr1UJry7X3s8Zry7KrnIgr48Cr43Wr1Dtr4vka1Y qFW3Ww1rCw1qvaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkjb4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIEc7CjxV AFwI0_Gr0_Gr1UM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40E x7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x 0Yz7v_Jr0_Gr1lF7xvr2IY64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1l42xK82IYc2Ij 64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x 8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a6rW5MIIYrxkI7VAKI48JMIIF0xvE 2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42 xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIE c7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x07UZ18PUUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAQASBF1jj4V8RQABsb X-CFilter-Loop: Reflected Precedence: bulk List-ID: On Tue, 2022-11-15 at 21:11 -0500, Paul Moore wrote: > On Tue, Nov 15, 2022 at 12:57 PM Roberto Sassu > wrote: > > From: Roberto Sassu > > > > include/linux/lsm_hooks.h reports the result of the LSM infrastructure to > > the callers, not what LSMs should return to the LSM infrastructure. > > > > Clarify that and add that returning 1 from the LSMs means calling > > __vm_enough_memory() with cap_sys_admin set, 0 without. > > > > Signed-off-by: Roberto Sassu > > Reviewed-by: KP Singh > > --- > > include/linux/lsm_hooks.h | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h > > index 4ec80b96c22e..f40b82ca91e7 100644 > > --- a/include/linux/lsm_hooks.h > > +++ b/include/linux/lsm_hooks.h > > @@ -1411,7 +1411,9 @@ > > * Check permissions for allocating a new virtual mapping. > > * @mm contains the mm struct it is being added to. > > * @pages contains the number of pages. > > - * Return 0 if permission is granted. > > + * Return 0 if permission is granted by LSMs to the caller. LSMs should > > + * return 1 if __vm_enough_memory() should be called with > > + * cap_sys_admin set, 0 if not. > > I think this is a nice addition, but according to the code, any value > greater than zero will trigger the caller-should-have-CAP_SYS_ADMIN > behavior, not just 1. I suggest updating the comment. Ok, yes. Thanks. Roberto