From patchwork Thu Aug 13 14:48:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Thi=C3=A9baud_Weksteen?= X-Patchwork-Id: 11712567 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id AA1A4722 for ; Thu, 13 Aug 2020 14:50:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8ABD520791 for ; Thu, 13 Aug 2020 14:50:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="aPGwSU3D" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726583AbgHMOty (ORCPT ); Thu, 13 Aug 2020 10:49:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45512 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726567AbgHMOtm (ORCPT ); Thu, 13 Aug 2020 10:49:42 -0400 Received: from mail-qk1-x749.google.com (mail-qk1-x749.google.com [IPv6:2607:f8b0:4864:20::749]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B3B0C061383 for ; Thu, 13 Aug 2020 07:49:40 -0700 (PDT) Received: by mail-qk1-x749.google.com with SMTP id q18so4053906qkq.11 for ; Thu, 13 Aug 2020 07:49:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc:content-transfer-encoding; bh=fCGrFQfpfR4RJs5ZY7NRIygzu/+q9MlAoBreTUrZtKI=; b=aPGwSU3DH9pOxvTlq3Vws4aZ298GUILOkQMZa7HkaFW7bbJTqkoKkJdDwZOvXyfLCD WjttKGnSDKQuTC1kLTWwWqMTBI1ZC/bDZLtFG9RSer2bvKuAZn5jEnRuMjOj4r6Ulfap WUhkJRfcn3VqdCv6hUbALW+EyFpBFQmAJbqtUzpKSYKypkVGXwwmjX1BnrtwwWD+FMU5 eL1WKBbm1M6vWDjHt54UOwQEex3jLh5y7x1L4MlyPsaiXESuJaS6q/Mt00dYpzsCtLCU 8JYET0WCgV0cQCSmIMmVESEZN206LNEL8hAZAZ3dOdAq6vKM75+dnliVv9V5CxmTWOyl wTdQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc:content-transfer-encoding; bh=fCGrFQfpfR4RJs5ZY7NRIygzu/+q9MlAoBreTUrZtKI=; b=s3Bf9OR/RkywPIe5Yl4HCWROkCJGhtuWnPqD3Wuug+++TDWQUzxkkkd+hYYoLOJn33 gFKzCpHgGMqUCJ/+SpMzNorO6GGC9epIv/wYiSpMQ3a/6a/7nx2HC39Fi3hzUO/oqm7R TGBrwDdrBIEKmmtXiuObqy6kTr6UhDhk9ez7Uhcv6KzphDrMmqp6Y4tRzhVNUa3Bjbos WgSptxf3dGO0GbtIatFMM7jiGD2/RxiHr5NF8ciURAk9mRffqTf/i8ubMOfUTgxPjVzH 7Nw0e5kcIjS0dsXr6QUs4jcsJGFJvuN1mrxbge+q3ECGk3jqnZKex1ItOSKtiRLgYl30 eDbg== X-Gm-Message-State: AOAM533QjcicFT7U7bo+XnLXbgwY08ni0sip8pyM0+DcUxCOwDeFMqPC IJpQawHusz2PaiqbypHYVsQ1SJMGYw== X-Google-Smtp-Source: ABdhPJwhDd55Hhnw1Df03C8Ckc1A5yrI74oFew+g5Iv+yieF4ooMZEPMYiaFMZYEMPON3RGCK0rWZJmfPg== X-Received: by 2002:ad4:54c6:: with SMTP id j6mr5037154qvx.126.1597330178932; Thu, 13 Aug 2020 07:49:38 -0700 (PDT) Date: Thu, 13 Aug 2020 16:48:59 +0200 In-Reply-To: <20200813144914.737306-1-tweek@google.com> Message-Id: <20200813144914.737306-2-tweek@google.com> Mime-Version: 1.0 References: <20200813144914.737306-1-tweek@google.com> X-Mailer: git-send-email 2.28.0.236.gb10cc79966-goog Subject: [PATCH v2 2/2] selinux: add basic filtering for audit trace events From: " =?utf-8?q?Thi=C3=A9baud_Weksteen?= " To: Paul Moore Cc: Nick Kralevich , Peter Enderborg , " =?utf-8?q?Thi=C3=A9baud_Wekst?= =?utf-8?q?een?= " , Stephen Smalley , Eric Paris , Steven Rostedt , Ingo Molnar , Mauro Carvalho Chehab , "David S. Miller" , Rob Herring , Arnd Bergmann , linux-kernel@vger.kernel.org, selinux@vger.kernel.org Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org From: Peter Enderborg This patch adds further attributes to the event. These attributes are helpful to understand the context of the message and can be used to filter the events. There are three common items. Source context, target context and tclass. There are also items from the outcome of operation performed. An event is similar to: <...>-1309 [002] .... 6346.691689: selinux_audited: requested=0x4000000 denied=0x4000000 audited=0x4000000 result=-13 ssid=315 tsid=61 scontext=system_u:system_r:cupsd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:bin_t:s0 tclass=file With systems where many denials are occurring, it is useful to apply a filter. The filtering is a set of logic that is inserted with the filter file. Example: echo "tclass==\"file\" && ssid!=42" > events/avc/selinux_audited/filter This adds that we only get tclass=file but not for ssid 42. The trace can also have extra properties. Adding the user stack can be done with echo 1 > options/userstacktrace Now the output will be runcon-1365 [003] .... 6960.955530: selinux_audited: requested=0x4000000 denied=0x4000000 audited=0x4000000 result=-13 ssid=315 tsid=61 scontext=system_u:system_r:cupsd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:bin_t:s0 tclass=file runcon-1365 [003] .... 6960.955560: => <00007f325b4ce45b> => <00005607093efa57> Note that the ssid is the internal numeric representation of scontext and tsid is numeric for tcontext. They are useful for filtering. Signed-off-by: Peter Enderborg Reviewed-by: Thiébaud Weksteen --- v2 changes: - update changelog to include usage examples include/trace/events/avc.h | 41 ++++++++++++++++++++++++++++---------- security/selinux/avc.c | 22 +++++++++++--------- 2 files changed, 44 insertions(+), 19 deletions(-) diff --git a/include/trace/events/avc.h b/include/trace/events/avc.h index 07c058a9bbcd..ac5ef2e1c2c5 100644 --- a/include/trace/events/avc.h +++ b/include/trace/events/avc.h @@ -1,6 +1,7 @@ /* SPDX-License-Identifier: GPL-2.0 */ /* - * Author: Thiébaud Weksteen + * Authors: Thiébaud Weksteen + * Peter Enderborg */ #undef TRACE_SYSTEM #define TRACE_SYSTEM avc @@ -12,23 +13,43 @@ TRACE_EVENT(selinux_audited, - TP_PROTO(struct selinux_audit_data *sad), + TP_PROTO(struct selinux_audit_data *sad, + char *scontext, + char *tcontext, + const char *tclass + ), - TP_ARGS(sad), + TP_ARGS(sad, scontext, tcontext, tclass), TP_STRUCT__entry( - __field(unsigned int, tclass) - __field(unsigned int, audited) + __field(u32, requested) + __field(u32, denied) + __field(u32, audited) + __field(int, result) + __string(scontext, scontext) + __string(tcontext, tcontext) + __string(tclass, tclass) + __field(u32, ssid) + __field(u32, tsid) ), TP_fast_assign( - __entry->tclass = sad->tclass; - __entry->audited = sad->audited; + __entry->requested = sad->requested; + __entry->denied = sad->denied; + __entry->audited = sad->audited; + __entry->result = sad->result; + __entry->ssid = sad->ssid; + __entry->tsid = sad->tsid; + __assign_str(tcontext, tcontext); + __assign_str(scontext, scontext); + __assign_str(tclass, tclass); ), - TP_printk("tclass=%u audited=%x", - __entry->tclass, - __entry->audited) + TP_printk("requested=0x%x denied=0x%x audited=0x%x result=%d ssid=%u tsid=%u scontext=%s tcontext=%s tclass=%s", + __entry->requested, __entry->denied, __entry->audited, __entry->result, + __entry->ssid, __entry->tsid, __get_str(scontext), __get_str(tcontext), + __get_str(tclass) + ) ); #endif diff --git a/security/selinux/avc.c b/security/selinux/avc.c index b0a0af778b70..7de5cc5169af 100644 --- a/security/selinux/avc.c +++ b/security/selinux/avc.c @@ -705,35 +705,39 @@ static void avc_audit_post_callback(struct audit_buffer *ab, void *a) { struct common_audit_data *ad = a; struct selinux_audit_data *sad = ad->selinux_audit_data; - char *scontext; + char *scontext = NULL; + char *tcontext = NULL; + const char *tclass = NULL; u32 scontext_len; + u32 tcontext_len; int rc; - trace_selinux_audited(sad); - rc = security_sid_to_context(sad->state, sad->ssid, &scontext, &scontext_len); if (rc) audit_log_format(ab, " ssid=%d", sad->ssid); else { audit_log_format(ab, " scontext=%s", scontext); - kfree(scontext); } - rc = security_sid_to_context(sad->state, sad->tsid, &scontext, - &scontext_len); + rc = security_sid_to_context(sad->state, sad->tsid, &tcontext, + &tcontext_len); if (rc) audit_log_format(ab, " tsid=%d", sad->tsid); else { - audit_log_format(ab, " tcontext=%s", scontext); - kfree(scontext); + audit_log_format(ab, " tcontext=%s", tcontext); } - audit_log_format(ab, " tclass=%s", secclass_map[sad->tclass-1].name); + tclass = secclass_map[sad->tclass-1].name; + audit_log_format(ab, " tclass=%s", tclass); if (sad->denied) audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1); + trace_selinux_audited(sad, scontext, tcontext, tclass); + kfree(tcontext); + kfree(scontext); + /* in case of invalid context report also the actual context string */ rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext, &scontext_len);