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[82.17.115.212]) by smtp.gmail.com with ESMTPSA id r129-20020a1c2b87000000b0038e6a025d05sm17017899wmr.18.2022.04.19.08.03.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Apr 2022 08:03:38 -0700 (PDT) From: Aaron Tomlin To: mcgrof@kernel.org Cc: cl@linux.com, pmladek@suse.com, mbenes@suse.cz, christophe.leroy@csgroup.eu, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, atomlin@atomlin.com, ghalat@redhat.com Subject: [RFC PATCH v2 1/2] module: Make module_flags_taint() accept a module's taints bitmap directly Date: Tue, 19 Apr 2022 16:03:33 +0100 Message-Id: <20220419150334.3395019-2-atomlin@redhat.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220419150334.3395019-1-atomlin@redhat.com> References: <20220419150334.3395019-1-atomlin@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" No functional change. The purpose of this patch is to modify module_flags_taint() to accept a module's taints bitmap as a parameter and modifies all users accordingly. This is in preparation for module unload taint tracking support. Signed-off-by: Aaron Tomlin --- kernel/module/main.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/module/main.c b/kernel/module/main.c index 05a42d8fcd7a..ea78cec316dd 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -890,13 +890,13 @@ static inline int module_unload_init(struct module *m= od) } #endif /* CONFIG_MODULE_UNLOAD */ =20 -static size_t module_flags_taint(struct module *mod, char *buf) +static size_t module_flags_taint(unsigned long taints, char *buf) { size_t l =3D 0; int i; =20 for (i =3D 0; i < TAINT_FLAGS_COUNT; i++) { - if (taint_flags[i].module && test_bit(i, &mod->taints)) + if (taint_flags[i].module && test_bit(i, &taints)) buf[l++] =3D taint_flags[i].c_true; } =20 @@ -974,7 +974,7 @@ static ssize_t show_taint(struct module_attribute *matt= r, { size_t l; =20 - l =3D module_flags_taint(mk->mod, buffer); + l =3D module_flags_taint(mk->mod->taints, buffer); buffer[l++] =3D '\n'; return l; } @@ -2993,7 +2993,7 @@ char *module_flags(struct module *mod, char *buf) mod->state =3D=3D MODULE_STATE_GOING || mod->state =3D=3D MODULE_STATE_COMING) { buf[bx++] =3D '('; - bx +=3D module_flags_taint(mod, buf + bx); + bx +=3D module_flags_taint(mod->taints, buf + bx); /* Show a - for module-is-being-unloaded */ if (mod->state =3D=3D MODULE_STATE_GOING) buf[bx++] =3D '-'; --=20 2.34.1 From nobody Thu Jun 18 15:45:35 2026 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 CBDE8C433F5 for ; Tue, 19 Apr 2022 15:03:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353558AbiDSPGg (ORCPT ); Tue, 19 Apr 2022 11:06:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57826 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352211AbiDSPGa (ORCPT ); Tue, 19 Apr 2022 11:06:30 -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 A8B1B393DF for ; Tue, 19 Apr 2022 08:03:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1650380626; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IYNT6ZuIJiJoY8GI/zjU79USL2zsqTDoMA6bTiPxO48=; b=YD32mseR5Dyw0ZQcufcKilMJ8Xxjb+KrgHb7mGzZtR7TToRB8ccN/7cR84oQIsDblbq307 zt+8sds2o4reDPyyXmS9N3sXlWyzoxsxFRJjZNdNdPm2dIC0ZH/jC9PZjE8vTJKvM+RCZ3 +OBiFCZc5EL3juq1pjp0GsGlZY9/wVQ= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-235-6Vn3DnRSNB66y2ph5x7J0w-1; Tue, 19 Apr 2022 11:03:44 -0400 X-MC-Unique: 6Vn3DnRSNB66y2ph5x7J0w-1 Received: by mail-wr1-f71.google.com with SMTP id q4-20020adfc504000000b002079c9cc1bfso1997149wrf.11 for ; Tue, 19 Apr 2022 08:03:44 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=IYNT6ZuIJiJoY8GI/zjU79USL2zsqTDoMA6bTiPxO48=; b=dvhkCXhpRYeZ3H8EMIEB5zjsxcd5+k4JYIou/wd0J1HnCiXolm5Js1cKimrjZfc3h3 kQ4XpiNsKj0sdh1Y++S/RINGavpIvZqm6TUd4soawqhVuFPt3q036MycdUZefg1YUSTV evxkITnZk42Ve13mI2HPbnRXqs46JiyUIaInKJQ3DiDRddZfhx7J/P4AkAdbhSdVd/3w Yj8M49Gi37sJQZk0zVLRYj5Xp5wRWbFCYyC3IUtyeFNiXpyre1n0I/mxjxS6JjrP/CbN 8xRudnwtGXiehcVcmi73qhrJ9mdhwq3fjbbaxaLf2w1XctX7XjAqZWhsluDZp+vDGJIA 3qnw== X-Gm-Message-State: AOAM530pW3a1ft0tznIpoTm8OWSD9RXfOp8vIl2Agfre7miulWFHchoq K5gtkVwCREO417h+5ky5Fdrm8ewCoQ177EKLLG9WnedGuY6ROGS6+hsnPVwvvWb7rrXJ5A7gnwM kyOBwaiaG52KdCqXjHrk/Ghk= X-Received: by 2002:adf:eed0:0:b0:207:9b35:62c4 with SMTP id a16-20020adfeed0000000b002079b3562c4mr11886869wrp.509.1650380622605; Tue, 19 Apr 2022 08:03:42 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxcok70XsxVaMKU6HNbr90avt8VZ6+aoTLI8CVNsPXJij7rNpI0D8baGm7YWjMF9VJH6qWsng== X-Received: by 2002:adf:eed0:0:b0:207:9b35:62c4 with SMTP id a16-20020adfeed0000000b002079b3562c4mr11886858wrp.509.1650380622364; Tue, 19 Apr 2022 08:03:42 -0700 (PDT) Received: from localhost (cpc111743-lutn13-2-0-cust979.9-3.cable.virginm.net. [82.17.115.212]) by smtp.gmail.com with ESMTPSA id t2-20020a1c4602000000b003917d43d339sm13184166wma.4.2022.04.19.08.03.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Apr 2022 08:03:41 -0700 (PDT) From: Aaron Tomlin To: mcgrof@kernel.org Cc: cl@linux.com, pmladek@suse.com, mbenes@suse.cz, christophe.leroy@csgroup.eu, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, atomlin@atomlin.com, ghalat@redhat.com Subject: [RFC PATCH v2 2/2] module: Introduce module unload taint tracking Date: Tue, 19 Apr 2022 16:03:34 +0100 Message-Id: <20220419150334.3395019-3-atomlin@redhat.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220419150334.3395019-1-atomlin@redhat.com> References: <20220419150334.3395019-1-atomlin@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Currently, only the initial module that tainted the kernel is recorded e.g. when an out-of-tree module is loaded. The purpose of this patch is to allow the kernel to maintain a record of each unloaded module that taints the kernel. So, in addition to displaying a list of linked modules (see print_modules()) e.g. in the event of a detected bad page, unloaded modules that carried a taint/or taints are displayed too. If a previously unloaded module with a taint/or tains is loaded once again and then a count will be shown accordingly. The number of tracked modules is not fixed. This feature is disabled by default. Signed-off-by: Aaron Tomlin --- init/Kconfig | 11 +++++++ kernel/module/main.c | 68 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 79 insertions(+) diff --git a/init/Kconfig b/init/Kconfig index ddcbefe535e9..6b30210f787d 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -2118,6 +2118,17 @@ config MODULE_FORCE_UNLOAD rmmod). This is mainly for kernel developers and desperate users. If unsure, say N. =20 +config MODULE_UNLOAD_TAINT_TRACKING + bool "Tainted module unload tracking" + depends on MODULE_UNLOAD + default n + help + This option allows you to maintain a record of each unloaded + module that tainted the kernel. In addition to displaying a + list of linked (or loaded) modules e.g. on detection of a bad + page (see bad_page()), the aforementioned details are also + shown. If unsure, say N. + config MODVERSIONS bool "Module versioning support" help diff --git a/kernel/module/main.c b/kernel/module/main.c index ea78cec316dd..0f7df9ac25ce 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -68,6 +68,16 @@ */ DEFINE_MUTEX(module_mutex); LIST_HEAD(modules); +#ifdef CONFIG_MODULE_UNLOAD_TAINT_TRACKING +static LIST_HEAD(unloaded_tainted_modules); + +struct mod_unload_taint { + struct list_head list; + char name[MODULE_NAME_LEN]; + unsigned long taints; + u64 count; +}; +#endif =20 /* Work queue for freeing init sections in success case */ static void do_free_init(struct work_struct *w); @@ -150,6 +160,42 @@ int unregister_module_notifier(struct notifier_block *= nb) } EXPORT_SYMBOL(unregister_module_notifier); =20 +#ifdef CONFIG_MODULE_UNLOAD_TAINT_TRACKING +static int try_add_tainted_module(struct module *mod) +{ + struct mod_unload_taint *mod_taint; + + module_assert_mutex_or_preempt(); + + list_for_each_entry_rcu(mod_taint, &unloaded_tainted_modules, list, + lockdep_is_held(&module_mutex)) { + size_t len =3D strlen(mod_taint->name); + + if (len =3D=3D strlen(mod->name) && !memcmp(mod_taint->name, mod->name, = len) && + mod_taint->taints & mod->taints) { + mod_taint->count++; + goto out; + } + } + + mod_taint =3D kmalloc(sizeof(*mod_taint), GFP_KERNEL); + if (unlikely(!mod_taint)) + return -ENOMEM; + strlcpy(mod_taint->name, mod->name, + MODULE_NAME_LEN); + mod_taint->taints =3D mod->taints; + list_add_rcu(&mod_taint->list, &unloaded_tainted_modules); + mod_taint->count =3D 0; +out: + return 0; +} +#else /* MODULE_UNLOAD_TAINT_TRACKING */ +static int try_add_tainted_module(struct module *mod) +{ + return 0; +} +#endif + /* * We require a truly strong try_module_get(): 0 means success. * Otherwise an error is returned due to ongoing or failed @@ -1201,6 +1247,9 @@ static void free_module(struct module *mod) module_bug_cleanup(mod); /* Wait for RCU-sched synchronizing before releasing mod->list and buglis= t. */ synchronize_rcu(); + if (try_add_tainted_module(mod)) + pr_err("%s: adding tainted module to the unloaded tainted modules list f= ailed.\n", + mod->name); mutex_unlock(&module_mutex); =20 /* Clean up CFI for the module. */ @@ -3126,6 +3175,9 @@ struct module *__module_text_address(unsigned long ad= dr) void print_modules(void) { struct module *mod; +#ifdef CONFIG_MODULE_UNLOAD_TAINT_TRACKING + struct mod_unload_taint *mod_taint; +#endif char buf[MODULE_FLAGS_BUF_SIZE]; =20 printk(KERN_DEFAULT "Modules linked in:"); @@ -3136,6 +3188,22 @@ void print_modules(void) continue; pr_cont(" %s%s", mod->name, module_flags(mod, buf)); } +#ifdef CONFIG_MODULE_UNLOAD_TAINT_TRACKING + if (!list_empty(&unloaded_tainted_modules)) { + printk(KERN_DEFAULT "\nUnloaded tainted modules:"); + list_for_each_entry_rcu(mod_taint, &unloaded_tainted_modules, + list) { + size_t l; + + l =3D module_flags_taint(mod_taint->taints, buf); + buf[l++] =3D '\0'; + pr_cont(" %s(%s)%s", mod_taint->name, buf, + mod_taint->count ? ":" : ""); + if (mod_taint->count) + pr_cont("%llu", mod_taint->count); + } +#endif + } preempt_enable(); if (last_unloaded_module[0]) pr_cont(" [last unloaded: %s]", last_unloaded_module); --=20 2.34.1