From patchwork Tue Feb 22 10:38:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 12754859 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 3B11EC433F5 for ; Tue, 22 Feb 2022 10:39:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231314AbiBVKjs (ORCPT ); Tue, 22 Feb 2022 05:39:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231310AbiBVKjp (ORCPT ); Tue, 22 Feb 2022 05:39:45 -0500 Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFFE51520E9; Tue, 22 Feb 2022 02:39:20 -0800 (PST) Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4K2wdd1GRcz9sT4; Tue, 22 Feb 2022 11:39:17 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id zEPSRavfLS7v; Tue, 22 Feb 2022 11:39:17 +0100 (CET) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4K2wdb6mXrz9sT2; Tue, 22 Feb 2022 11:39:15 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id D3E178B764; Tue, 22 Feb 2022 11:39:15 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id 66W3h899ZoQ9; Tue, 22 Feb 2022 11:39:15 +0100 (CET) Received: from PO20335.IDSI0.si.c-s.fr (unknown [172.25.230.108]) by messagerie.si.c-s.fr (Postfix) with ESMTP id A573F8B77A; Tue, 22 Feb 2022 11:39:15 +0100 (CET) Received: from PO20335.IDSI0.si.c-s.fr (localhost [127.0.0.1]) by PO20335.IDSI0.si.c-s.fr (8.17.1/8.16.1) with ESMTPS id 21MAd7pD1076222 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Tue, 22 Feb 2022 11:39:07 +0100 Received: (from chleroy@localhost) by PO20335.IDSI0.si.c-s.fr (8.17.1/8.17.1/Submit) id 21MAd7B91076221; Tue, 22 Feb 2022 11:39:07 +0100 X-Authentication-Warning: PO20335.IDSI0.si.c-s.fr: chleroy set sender to christophe.leroy@csgroup.eu using -f From: Christophe Leroy To: Aaron Tomlin , Luis Chamberlain , linux-modules@vger.kernel.org Cc: Christophe Leroy , linux-kernel@vger.kernel.org Subject: [PATCH v1 5/6] module: Rework layout alignment to avoid BUG_ON()s Date: Tue, 22 Feb 2022 11:38:59 +0100 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1645526317; l=4076; s=20211009; h=from:subject:message-id; bh=CYUOt3ARLhIdcgn+cH3ZQO7m4/B5fdRfsQumL45ql/U=; b=H9lAZ2UAafA4WnlxO3PpmepqcWE/H+KiGkreefXl3K+25hBgbYivleAWwW1s/NzI1+F7KCmXhEDs SIs4Mtn+DZKkITli2SWxEItJqqLsZ4TxgEtPTulMFl0q1ngoZIw1 X-Developer-Key: i=christophe.leroy@csgroup.eu; a=ed25519; pk=HIzTzUj91asvincQGOFx6+ZF5AoUuP9GdOtQChs7Mm0= Precedence: bulk List-ID: Perform layout alignment verification up front and WARN_ON() and fail module loading instead of crashing the machine. Signed-off-by: Christophe Leroy --- kernel/module/internal.h | 1 + kernel/module/main.c | 5 +++++ kernel/module/strict_rwx.c | 28 +++++++++++++++++++--------- 3 files changed, 25 insertions(+), 9 deletions(-) diff --git a/kernel/module/internal.h b/kernel/module/internal.h index b80a746b2e5a..32add08e7895 100644 --- a/kernel/module/internal.h +++ b/kernel/module/internal.h @@ -187,6 +187,7 @@ void module_enable_nx(const struct module *mod); void module_enable_x(const struct module *mod); int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, char *secstrings, struct module *mod); +bool module_check_misalignment(const struct module *mod); #ifdef CONFIG_MODULE_SIG int module_sig_check(struct load_info *info, int flags); diff --git a/kernel/module/main.c b/kernel/module/main.c index 47addf849ef7..4876e2beb5b6 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -2596,6 +2596,9 @@ static int complete_formation(struct module *mod, struct load_info *info) /* This relies on module_mutex for list integrity. */ module_bug_finalize(info->hdr, info->sechdrs, mod); + if (module_check_misalignment(mod)) + goto out_misaligned; + module_enable_ro(mod, false); module_enable_nx(mod); module_enable_x(mod); @@ -2609,6 +2612,8 @@ static int complete_formation(struct module *mod, struct load_info *info) return 0; +out_misaligned: + err = -EINVAL; out: mutex_unlock(&module_mutex); return err; diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c index b023cea06af0..3966198a4fc0 100644 --- a/kernel/module/strict_rwx.c +++ b/kernel/module/strict_rwx.c @@ -42,9 +42,6 @@ static void frob_text(const struct module_layout *layout, static void frob_rodata(const struct module_layout *layout, int (*set_memory)(unsigned long start, int num_pages)) { - BUG_ON(!PAGE_ALIGNED(layout->base)); - BUG_ON(!PAGE_ALIGNED(layout->text_size)); - BUG_ON(!PAGE_ALIGNED(layout->ro_size)); set_memory((unsigned long)layout->base + layout->text_size, (layout->ro_size - layout->text_size) >> PAGE_SHIFT); } @@ -52,9 +49,6 @@ static void frob_rodata(const struct module_layout *layout, static void frob_ro_after_init(const struct module_layout *layout, int (*set_memory)(unsigned long start, int num_pages)) { - BUG_ON(!PAGE_ALIGNED(layout->base)); - BUG_ON(!PAGE_ALIGNED(layout->ro_size)); - BUG_ON(!PAGE_ALIGNED(layout->ro_after_init_size)); set_memory((unsigned long)layout->base + layout->ro_size, (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT); } @@ -62,13 +56,29 @@ static void frob_ro_after_init(const struct module_layout *layout, static void frob_writable_data(const struct module_layout *layout, int (*set_memory)(unsigned long start, int num_pages)) { - BUG_ON(!PAGE_ALIGNED(layout->base)); - BUG_ON(!PAGE_ALIGNED(layout->ro_after_init_size)); - BUG_ON(!PAGE_ALIGNED(layout->size)); set_memory((unsigned long)layout->base + layout->ro_after_init_size, (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT); } +static bool layout_check_misalignment(const struct module_layout *layout) +{ + return WARN_ON(!PAGE_ALIGNED(layout->base)) || + WARN_ON(!PAGE_ALIGNED(layout->text_size)) || + WARN_ON(!PAGE_ALIGNED(layout->ro_size)) || + WARN_ON(!PAGE_ALIGNED(layout->ro_after_init_size)) || + WARN_ON(!PAGE_ALIGNED(layout->size)); +} + +bool module_check_misalignment(const struct module *mod) +{ + if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) + return false; + + return layout_check_misalignment(&mod->core_layout) || + layout_check_misalignment(&mod->data_layout) || + layout_check_misalignment(&mod->init_layout); +} + void module_enable_x(const struct module *mod) { if (!PAGE_ALIGNED(mod->core_layout.base) ||