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 68F85C05027 for ; Mon, 6 Feb 2023 22:54:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229839AbjBFWyL (ORCPT ); Mon, 6 Feb 2023 17:54:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229731AbjBFWyK (ORCPT ); Mon, 6 Feb 2023 17:54:10 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C842C19697 for ; Mon, 6 Feb 2023 14:53:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675724001; 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=+u1OHKdh6SWWXlvEFuLIidGMEw5HN4SNIPpsLH0U2KY=; b=ZJHiAq2fJO97FI3XE0laXntR1TLcD09UWoL0W//N4YzUQEyutM3VnbJC6g0bVIOtBvlydI UwPXrY9agenZNO9UhEiMBMsUrHwfwdGz8be49uU82Zz7aSbqDLhpakV9jwERSWrJ5h2h02 BlKFITLykxO209Svq5F3uV0f+sX/m5s= 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-277-LJNDADelN1u2WiOMFnKnqQ-1; Mon, 06 Feb 2023 17:53:18 -0500 X-MC-Unique: LJNDADelN1u2WiOMFnKnqQ-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 C7A8E811E6E; Mon, 6 Feb 2023 22:53:17 +0000 (UTC) Received: from x2.localnet (unknown [10.22.11.79]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B1129400F756; Mon, 6 Feb 2023 22:52:47 +0000 (UTC) From: Steve Grubb To: Linux-Audit Mailing List , LKML , linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, Richard Guy Briggs Cc: Paul Moore , Eric Paris , Richard Guy Briggs , Jan Kara , Amir Goldstein Subject: Re: [PATCH v7 0/3] fanotify: Allow user space to pass back additional audit info Date: Mon, 06 Feb 2023 17:52:20 -0500 Message-ID: <12168436.O9o76ZdvQC@x2> Organization: Red Hat In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Richard, On Friday, February 3, 2023 4:35:13 PM EST Richard Guy Briggs wrote: > 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 patchset defines a new flag (FAN_INFO) and new extensions that > define additional information which are appended after the response > structure returned from user space on a permission event. The appended > information is organized with headers containing a type and size that > can be delegated to interested subsystems. One new information type is > defined to audit the triggering rule number. > > A newer kernel will work with an older userspace and an older kernel > will behave as expected and reject a newer userspace, leaving it up to > the newer userspace to test appropriately and adapt as necessary. This > is done by providing a a fully-formed FAN_INFO extension but setting the > fd to FAN_NOFD. On a capable kernel, it will succeed but issue no audit > record, whereas on an older kernel it will fail. I have taken the patches and built a new kernel. Everything looks good to me on the audit side. It's acting as expected. You can put me down for an ACK or tested-by or whatever is appropriate. -Steve > The audit function was updated to log the additional information in the > AUDIT_FANOTIFY record. The following are examples of the new record > format: > type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1 > fan_info=3137 subj_trust=3 obj_trust=5 type=FANOTIFY > msg=audit(1659730979.839:284): resp=1 fan_type=0 fan_info=0 subj_trust=2 > obj_trust=2 > > 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/all/cover.1652730821.git.rgb@redhat.com > > v4: > - scrap FAN_INVALID_RESPONSE_MASK in favour of original to catch invalid > response == 0 - introduce FANOTIFY_RESPONSE_* macros > - uapi: remove union > - keep original struct fanotify_response, add fan_info infra starting with > audit reason - uapi add struct fanotify_response_info_header{type/pad/len} > and struct fanotify_response_info_audit_rule{hdr/rule} - rename fan_ctx= > to fan_info=, FAN_EXTRA to FAN_INFO > - change event struct from type/buf to len/buf > - enable multiple info extensions in one message > - hex encode fan_info in __audit_fanotify() > - record type FANOTIFY extended to "type=FANOTIFY > msg=audit(1659730979.839:284): resp=1 fan_type=0 fan_info=3F" Link: > https://lore.kernel.org/all/cover.1659996830.git.rgb@redhat.com > > v5: > - fixed warnings in p2/4 and p3/4 found by > - restore original behaviour for !FAN_INFO case and fanotify_get_response() > - rename member audit_rule to rule_number > - eliminate memory leak of info_buf on failure (no longer dynamic) > - rename buf:info, count:info_len, c:remain, ib:infop > - fix pr_debug > - return -ENOENT on FAN_INFO and fd==FAN_NOFD to signal new kernel > - fanotify_write() remove redundant size check > - add u32 subj_trust obj_trust fields with unknown value "2" > - split out to helper process_access_response_info() > - restore finish_permission_event() response_struct to u32 > - assume and enforce one rule to audit, pass struct directly to > __audit_fanotify() - change fanotify_perm_event struct to union > hdr/audir_rule > - add vspace to fanotify_write() and process_access_response_info() > - squash 3/4 with 4/4 > - fix v3 and v4 links > Link: https://lore.kernel.org/all/cover.1670606054.git.rgb@redhat.com > > v6: > - simplify __audit_fanotify() from audit_log_format/audit_log_n_hex to > audit_log/%X - add comment to clarify {subj,obj}_trust values > - remove fd processing from process_access_response_info() > - return info_len immediately from process_access_response() on FAN_NOFD > after process_access_response_info() Link: > https://lore.kernel.org/all/cover.1673989212.git.rgb@redhat.com > > v7: > - change non FAN_INFO case to "0" > - change from if-return to switch(type)-case, which now ignores non-audit > info Link: https://lore.kernel.org/all/cover.1675373475.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,audit: Allow audit to use the full permission event response > > fs/notify/fanotify/fanotify.c | 8 ++- > fs/notify/fanotify/fanotify.h | 6 +- > fs/notify/fanotify/fanotify_user.c | 88 ++++++++++++++++++++++-------- > include/linux/audit.h | 9 +-- > include/linux/fanotify.h | 5 ++ > include/uapi/linux/fanotify.h | 30 +++++++++- > kernel/auditsc.c | 18 +++++- > 7 files changed, 131 insertions(+), 33 deletions(-)