From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 06C7814A0A8 for ; Thu, 22 May 2025 03:24:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747884271; cv=none; b=Bo0cYx6xi+pvyxGC5r156d9kNbQZx2NifgyR+qJjP+UziYkBV6S3jA1e0QNRpyIFAmkyOtnBIBTc/xMqeNApjGV47cSze31tqJNMpF90qtoY35Kx0diUVC5NttXTnyMd6kBG+mB2gTgqnOB2X5pwbBcg2d2EFdR3iOA79oFLEOU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747884271; c=relaxed/simple; bh=wDKUKOvuZiIsXBV7oI1I/zbaXpEd9HOGbHO7kI1RbM4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Pw6+5RFGpfu7KekxzP+yaDIcuQWWE7xLj4MWwBnLkN0iyDls4gQrn7x0/WBT4z8nnQ4FQNDMjsd5dHssK3oGkBSUoGoAQEVsDbXHDY2HlpkxeM/DBgvesynZ9kSF/pVCod7vEYi7iNnljblggwGX2BTkoJlPx2oTqW6mW0ZWDEk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=M1OcNt0b; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="M1OcNt0b" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1747884268; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1NHK1vKyf9FKDgti3HXT6gv903PyEoUwrQudAnu4zik=; b=M1OcNt0bd9rMmZrmsS16FxQySbYyim5vSz6tVB4vmJRIzJUfRunM/dU4xUBzkbZ5wvfu7L z5dmGAHce/0leEaYOt0A2KUJ1Xs7g+0oG03sB/+BvKhHBvDScC8y5DVyLOL2EpIR/O8T8U EDy9+0E0rUdE8izHS+FeJC3aprUOC+0= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-440-bTLkcJn9PpK0UXXLRcp43g-1; Wed, 21 May 2025 23:24:22 -0400 X-MC-Unique: bTLkcJn9PpK0UXXLRcp43g-1 X-Mimecast-MFC-AGG-ID: bTLkcJn9PpK0UXXLRcp43g_1747884261 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 436C518003FC; Thu, 22 May 2025 03:24:20 +0000 (UTC) Received: from localhost (unknown [10.72.112.172]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0149118003FC; Thu, 22 May 2025 03:24:17 +0000 (UTC) Date: Thu, 22 May 2025 11:24:13 +0800 From: Baoquan He To: Mimi Zohar Cc: linux-integrity@vger.kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, pmenzel@molgen.mpg.de, coxu@redhat.com, ruyang@redhat.com, chenste@linux.microsoft.com Subject: Re: [PATCH] ima: add a knob ima= to make IMA be able to be disabled Message-ID: References: <20250515233953.14685-1-bhe@redhat.com> <1d2848fe45dbf58707cecf16c4fc46b179e24415.camel@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1d2848fe45dbf58707cecf16c4fc46b179e24415.camel@linux.ibm.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 On 05/21/25 at 08:54am, Mimi Zohar wrote: > On Fri, 2025-05-16 at 08:22 +0800, Baoquan He wrote: > > CC kexec list. > > > > On 05/16/25 at 07:39am, Baoquan He wrote: > > > Kdump kernel doesn't need IMA functionality, and enabling IMA will cost > > > extra memory. It would be very helpful to allow IMA to be disabled for > > > kdump kernel. Thanks a lot for careufl reviewing and great suggestions. > > The real question is not whether kdump needs "IMA", but whether not enabling > IMA in the kdump kernel could be abused. The comments below don't address > that question but limit/emphasize, as much as possible, turning IMA off is > limited to the kdump kernel. Are you suggesting removing below paragraph from patch log because they are redundant? I can remove it in v2 if yes. > > > > > > > And Coiby also mentioned that for kdump kernel incorrect ima-policy loaded > > > by systemd could cause kdump kernel hang, and it's possible the booting > > > process may be stopped by a strict, albeit syntax-correct policy and users > > > can't log into the system to fix the policy. In these cases, allowing to > > > disable IMA is very helpful too for kdump kernel. > > > > > > Hence add a knob ima=on|off here to allow people to disable IMA in kdump > > > kenrel if needed. > > ^kernel Will change. > > > > > > > Signed-off-by: Baoquan He > > > --- > > >  .../admin-guide/kernel-parameters.txt         |  5 +++++ > > >  security/integrity/ima/ima_main.c             | 22 +++++++++++++++++++ > > >  2 files changed, 27 insertions(+) > > > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > > > b/Documentation/admin-guide/kernel-parameters.txt > > > index d9fd26b95b34..762fb6ddcc24 100644 > > > --- a/Documentation/admin-guide/kernel-parameters.txt > > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > > @@ -2202,6 +2202,11 @@ > > >   different crypto accelerators. This option can be > > > used > > >   to achieve best performance for particular HW. > > >   > > > + ima= [IMA] Enable or disable IMA > > > + Format: { "off" | "on" } > > > + Default: "on" > > > + Note that this is only useful for kdump kernel. > > Instead of "useful" I would prefer something clearer like "limited". Makes sense, will change. > > > > + > > >   init= [KNL] > > >   Format: > > >   Run specified binary instead of /sbin/init as > > > init > > > diff --git a/security/integrity/ima/ima_main.c > > > b/security/integrity/ima/ima_main.c > > > index f3e7ac513db3..07af5c6af138 100644 > > > --- a/security/integrity/ima/ima_main.c > > > +++ b/security/integrity/ima/ima_main.c > > > @@ -27,6 +27,7 @@ > > >  #include > > >  #include > > >  #include > > > +#include > > >   > > >  #include "ima.h" > > >   > > > @@ -38,11 +39,27 @@ int ima_appraise; > > >   > > >  int __ro_after_init ima_hash_algo = HASH_ALGO_SHA1; > > >  static int hash_setup_done; > > > +static int ima_disabled; > > Like the ima_hash_algo variable definition above, ima_disabled should be > defined as __ro_after_init. Will add __ro_after_init. > > > >   > > >  static struct notifier_block ima_lsm_policy_notifier = { > > >   .notifier_call = ima_lsm_policy_change, > > >  }; > > >   > > > +static int __init ima_setup(char *str) > > > +{ > > is_kdump_kernel() should also be called here, before the tests below. > Something like: > > + if (!is_kdump_kernel()) { > + pr_info("Warning ima setup option only permitted in kdump"); > + return 1; > + } Sure, will change as suggested. > > > > + if (strncmp(str, "off", 3) == 0) > > > + ima_disabled = 1; > > > + else if (strncmp(str, "on", 2) == 0) > > > + ima_disabled = 0; > > > + else > > > + pr_err("Invalid ima setup option: \"%s\" , please specify > > > ima=on|off.", str); > > > + > > > + return 1; > > > +} > > > +__setup("ima=", ima_setup); > > > + > > > + > > > + > > Remove the extraneous blank line. sure. > > > >  static int __init hash_setup(char *str) > > >  { > > >   struct ima_template_desc *template_desc = > > > ima_template_desc_current(); > > > @@ -1184,6 +1201,11 @@ static int __init init_ima(void) > > >  { > > >   int error; > > >   > > > + if (ima_disabled && is_kdump_kernel()) { > > > + pr_info("IMA functionality is disabled"); > > > + return 0; > > > + } > > > + > > Even with the additional call to is_kdump_kernel() in ima_setup, please keep > the is_kdump_kernel() test here as well. Even though the code is self > describing, please add a one line comment emphasizing disabling IMA is limited > to kdump. OK, will keep code here as this v1 is and add one line of comment at above. Thanks again. > > > >   ima_appraise_parse_cmdline(); > > >   ima_init_template_list(); > > >   hash_setup(CONFIG_IMA_DEFAULT_HASH); > > > -- > > > 2.41.0 > > > > > > > > > thanks, > > Mimi >