From patchwork Mon May 16 20:22:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Richard Guy Briggs X-Patchwork-Id: 12851403 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 5D8DBC43217 for ; Mon, 16 May 2022 20:47:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240564AbiEPUr4 (ORCPT ); Mon, 16 May 2022 16:47:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53254 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245317AbiEPUpC (ORCPT ); Mon, 16 May 2022 16:45:02 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 1EDBE4839B for ; Mon, 16 May 2022 13:22:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652732558; 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; bh=X/hW8heDuAXy8YNMnWK8A1edgrFI+3cNEUxDQuZBP/o=; b=Xxi8lf+jum4NhNVwDJ7VxVyggX07XtV1CTH0b8AyUnALYWC6GXHdfmnXJJhOygJ55KnqJ/ fXYL+LzuVo9bHOrR0mBAq+TdwJTrRiMUwvuAfi1u6amCoXUKxRN1ROloRtgj21hGjWrj/g tV2NQym5OYMu7oG0sAgqygPX5UG1Fn0= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-595-0tAPI_2OPfONwKeE-BDOkg-1; Mon, 16 May 2022 16:22:36 -0400 X-MC-Unique: 0tAPI_2OPfONwKeE-BDOkg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 26CC1811E75; Mon, 16 May 2022 20:22:36 +0000 (UTC) Received: from madcap2.tricolour.com (unknown [10.22.50.7]) by smtp.corp.redhat.com (Postfix) with ESMTP id A783840CF8E2; Mon, 16 May 2022 20:22:34 +0000 (UTC) From: Richard Guy Briggs To: Linux-Audit Mailing List , LKML , linux-fsdevel@vger.kernel.org Cc: Paul Moore , Eric Paris , Steve Grubb , Richard Guy Briggs , Jan Kara , Amir Goldstein Subject: [PATCH v3 0/3] fanotify: Allow user space to pass back additional audit info Date: Mon, 16 May 2022 16:22:21 -0400 Message-Id: MIME-Version: 1.0 Content-type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org The Fanotify API can be used for access control by requesting permission event notification. The user space tooling that uses it may have a complicated policy that inherently contains additional context for the decision. If this information were available in the audit trail, policy writers can close the loop on debugging policy. Also, if this additional information were available, it would enable the creation of tools that can suggest changes to the policy similar to how audit2allow can help refine labeled security. This patch defines 2 additional fields within the response structure returned from user space on a permission event. The first field is 32 bits for the context type. The context type will describe what the meaning is of the second field. The audit system will separate the pieces and log them individually. The audit function was updated to log the additional information in the AUDIT_FANOTIFY record. The following is an example of the new record format: type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1 fan_ctx=17 changelog: v1: - first version by Steve Grubb Link: https://lore.kernel.org/r/2042449.irdbgypaU6@x2 v2: - enhancements suggested by Jan Kara - 1/3 change %d to %u in pr_debug - 2/3 change response from __u32 to __u16 - mod struct fanotify_response and fanotify_perm_event add extra_info_type, extra_info_buf - extra_info_buf size max FANOTIFY_MAX_RESPONSE_EXTRA_LEN, add struct fanotify_response_audit_rule - extend debug statements - remove unneeded macros - [internal] change interface to finish_permission_event() and process_access_response() - 3/3 update format of extra information - [internal] change interface to audit_fanotify() - change ctx_type= to fan_type= Link: https://lore.kernel.org/r/cover.1651174324.git.rgb@redhat.com v3: - 1/3 switch {,__}audit_fanotify() from uint to u32 - 2/3 re-add fanotify_get_response switch case FAN_DENY: to avoid unnecessary churn - add FAN_EXTRA flag to indicate more info and break with old kernel - change response from u16 to u32 to avoid endian issues - change extra_info_buf to union - move low-cost fd check earlier - change FAN_RESPONSE_INFO_AUDIT_NONE to FAN_RESPONSE_INFO_NONE - switch to u32 for internal and __u32 for uapi Link: https://lore.kernel.org/r/cover.1652724390.git.rgb@redhat.com Richard Guy Briggs (3): fanotify: Ensure consistent variable type for response fanotify: define struct members to hold response decision context fanotify: Allow audit to use the full permission event response fs/notify/fanotify/fanotify.c | 6 ++- fs/notify/fanotify/fanotify.h | 4 +- fs/notify/fanotify/fanotify_user.c | 76 +++++++++++++++++++----------- include/linux/audit.h | 9 ++-- include/linux/fanotify.h | 3 ++ include/uapi/linux/fanotify.h | 22 ++++++++- kernel/auditsc.c | 18 +++++-- 7 files changed, 100 insertions(+), 38 deletions(-)