From patchwork Tue Mar 22 14:03:36 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aaron Tomlin X-Patchwork-Id: 12788402 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 1D24DC433EF for ; Tue, 22 Mar 2022 14:04:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233175AbiCVOFl (ORCPT ); Tue, 22 Mar 2022 10:05:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236178AbiCVOFg (ORCPT ); Tue, 22 Mar 2022 10:05:36 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id EB10B3190F for ; Tue, 22 Mar 2022 07:04:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1647957847; 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=Izr11YJzmvAe+LaxIWKRd054OpBnoHmXtcTT48M4YnE=; b=aMsbGiN01aDup0LqrHZSh2WMXt0977mnZeCs+SWnhTCsrMwL51f8+iAJ53AE9sbYtAMh3A WEKKrWh3xP/VBOcNdr6hKbF96nmutM4HsSl4H/enm8WvJkbk3HP2N8De/eKkdOFYDwvLbj PeB2gSnp5ddOkAtEwGT6qEr+C6SkXYE= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-322-iP_M20fXNkGn1N3RFinMYw-1; Tue, 22 Mar 2022 10:04:05 -0400 X-MC-Unique: iP_M20fXNkGn1N3RFinMYw-1 Received: by mail-wm1-f70.google.com with SMTP id r64-20020a1c2b43000000b0038b59eb1940so1246163wmr.0 for ; Tue, 22 Mar 2022 07:04:05 -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=Izr11YJzmvAe+LaxIWKRd054OpBnoHmXtcTT48M4YnE=; b=VIkY+NNQQMiGsuifswhuPaM9s8HFFolCdg1hFSm6m13vj5bOlNF1NK46NzF/RdhGx9 EFkHr6NTf4lpZhMIsXWSoUT3A8fBEi7OtGD3IQivyqIqVZHJgYnRpiB5kyc48qCsOGdm TyLzSpohxuupmdM++4gDlpYVnKc9RioHzatATSY3LFKw56gkFnn90Bf+Hr02VTBuIPkU D1I8AwMgUbTnfPk0U5FDnc3NJ7d2RPHRlpBHGyngqcpASxsBPZhPrCV8zKMAubipcQDu O4tE59NtM5vG2N5FNx2KHDKchGCeLOMDbc45Au9QEHLBGAkDWQLjWicmEf4pTa/KHi6s 3OAg== X-Gm-Message-State: AOAM531Ms3DL73H1popEFk5LAs1G2B6n7DWNAPSPmDWEIaStH0mOsao2 Kn3s+yX1sbmwu439uSECTVYlCMpjbi5TIyf1pa67bfrL50cmdG4Vww/ODpTzr+mRaRm1HK8tYEt ZYWdyROgLiGFoQEWdYaL/OoOm X-Received: by 2002:a5d:6da5:0:b0:1f1:f968:1a62 with SMTP id u5-20020a5d6da5000000b001f1f9681a62mr22920003wrs.227.1647957844335; Tue, 22 Mar 2022 07:04:04 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwraUVu51A8yjc6rSrKIzWZY7nohdSngiV3q7qZiwJD8eC39yzqqD4LjTZ+LYf2AGkd/SWOVg== X-Received: by 2002:a5d:6da5:0:b0:1f1:f968:1a62 with SMTP id u5-20020a5d6da5000000b001f1f9681a62mr22919968wrs.227.1647957844115; Tue, 22 Mar 2022 07:04:04 -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 b15-20020adfc74f000000b001e888b871a0sm15988346wrh.87.2022.03.22.07.04.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Mar 2022 07:04:03 -0700 (PDT) From: Aaron Tomlin To: mcgrof@kernel.org, christophe.leroy@csgroup.eu Cc: cl@linux.com, mbenes@suse.cz, akpm@linux-foundation.org, jeyu@kernel.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, void@manifault.com, atomlin@atomlin.com, allen.lkml@gmail.com, joe@perches.com, msuchanek@suse.de, oleksandr@natalenko.name, jason.wessel@windriver.com, pmladek@suse.com, daniel.thompson@linaro.org, hch@infradead.org Subject: [PATCH v12 06/14] module: Move strict rwx support to a separate file Date: Tue, 22 Mar 2022 14:03:36 +0000 Message-Id: <20220322140344.556474-7-atomlin@redhat.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220322140344.556474-1-atomlin@redhat.com> References: <20220322140344.556474-1-atomlin@redhat.com> MIME-Version: 1.0 Precedence: bulk List-ID: No functional change. This patch migrates code that makes module text and rodata memory read-only and non-text memory non-executable from core module code into kernel/module/strict_rwx.c. Reviewed-by: Christophe Leroy Signed-off-by: Aaron Tomlin --- kernel/module/Makefile | 1 + kernel/module/internal.h | 32 ++++++++++++ kernel/module/main.c | 99 +------------------------------------- kernel/module/strict_rwx.c | 85 ++++++++++++++++++++++++++++++++ 4 files changed, 120 insertions(+), 97 deletions(-) create mode 100644 kernel/module/strict_rwx.c diff --git a/kernel/module/Makefile b/kernel/module/Makefile index 88774e386276..d313c8472cb3 100644 --- a/kernel/module/Makefile +++ b/kernel/module/Makefile @@ -12,3 +12,4 @@ obj-$(CONFIG_MODULE_DECOMPRESS) += decompress.o obj-$(CONFIG_MODULE_SIG) += signing.o obj-$(CONFIG_LIVEPATCH) += livepatch.o obj-$(CONFIG_MODULES_TREE_LOOKUP) += tree_lookup.o +obj-$(CONFIG_STRICT_MODULE_RWX) += strict_rwx.o diff --git a/kernel/module/internal.h b/kernel/module/internal.h index f1682e3677be..a6895bb5598a 100644 --- a/kernel/module/internal.h +++ b/kernel/module/internal.h @@ -20,6 +20,17 @@ /* Maximum number of characters written by module_flags() */ #define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4) +/* + * Modules' sections will be aligned on page boundaries + * to ensure complete separation of code and data, but + * only when CONFIG_ARCH_HAS_STRICT_MODULE_RWX=y + */ +#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX +# define debug_align(X) PAGE_ALIGN(X) +#else +# define debug_align(X) (X) +#endif + extern struct mutex module_mutex; extern struct list_head modules; @@ -126,3 +137,24 @@ static inline struct module *mod_find(unsigned long addr) return NULL; } #endif /* CONFIG_MODULES_TREE_LOOKUP */ + +#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX +void frob_text(const struct module_layout *layout, int (*set_memory)(unsigned long start, + int num_pages)); +#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */ + +#ifdef CONFIG_STRICT_MODULE_RWX +void module_enable_ro(const struct module *mod, bool after_init); +void module_enable_nx(const struct module *mod); +int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, + char *secstrings, struct module *mod); + +#else /* !CONFIG_STRICT_MODULE_RWX */ +static inline void module_enable_nx(const struct module *mod) { } +static inline void module_enable_ro(const struct module *mod, bool after_init) {} +static inline int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, + char *secstrings, struct module *mod) +{ + return 0; +} +#endif /* CONFIG_STRICT_MODULE_RWX */ diff --git a/kernel/module/main.c b/kernel/module/main.c index 76b53880ad91..5cd63f14b1ef 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -63,17 +63,6 @@ #define CREATE_TRACE_POINTS #include -/* - * Modules' sections will be aligned on page boundaries - * to ensure complete separation of code and data, but - * only when CONFIG_ARCH_HAS_STRICT_MODULE_RWX=y - */ -#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX -# define debug_align(X) ALIGN(X, PAGE_SIZE) -#else -# define debug_align(X) (X) -#endif - /* * Mutex protects: * 1) List of modules (also safely readable with preempt_disable), @@ -1819,8 +1808,8 @@ static void mod_sysfs_teardown(struct module *mod) * whether we are strict. */ #ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX -static void frob_text(const struct module_layout *layout, - int (*set_memory)(unsigned long start, int num_pages)) +void frob_text(const struct module_layout *layout, + int (*set_memory)(unsigned long start, int num_pages)) { BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); BUG_ON((unsigned long)layout->text_size & (PAGE_SIZE-1)); @@ -1837,90 +1826,6 @@ static void module_enable_x(const struct module *mod) static void module_enable_x(const struct module *mod) { } #endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */ -#ifdef CONFIG_STRICT_MODULE_RWX -static void frob_rodata(const struct module_layout *layout, - int (*set_memory)(unsigned long start, int num_pages)) -{ - BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->text_size & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); - set_memory((unsigned long)layout->base + layout->text_size, - (layout->ro_size - layout->text_size) >> PAGE_SHIFT); -} - -static void frob_ro_after_init(const struct module_layout *layout, - int (*set_memory)(unsigned long start, int num_pages)) -{ - BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); - set_memory((unsigned long)layout->base + layout->ro_size, - (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT); -} - -static void frob_writable_data(const struct module_layout *layout, - int (*set_memory)(unsigned long start, int num_pages)) -{ - BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->size & (PAGE_SIZE-1)); - set_memory((unsigned long)layout->base + layout->ro_after_init_size, - (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT); -} - -static void module_enable_ro(const struct module *mod, bool after_init) -{ - if (!rodata_enabled) - return; - - set_vm_flush_reset_perms(mod->core_layout.base); - set_vm_flush_reset_perms(mod->init_layout.base); - frob_text(&mod->core_layout, set_memory_ro); - - frob_rodata(&mod->core_layout, set_memory_ro); - frob_text(&mod->init_layout, set_memory_ro); - frob_rodata(&mod->init_layout, set_memory_ro); - - if (after_init) - frob_ro_after_init(&mod->core_layout, set_memory_ro); -} - -static void module_enable_nx(const struct module *mod) -{ - frob_rodata(&mod->core_layout, set_memory_nx); - frob_ro_after_init(&mod->core_layout, set_memory_nx); - frob_writable_data(&mod->core_layout, set_memory_nx); - frob_rodata(&mod->init_layout, set_memory_nx); - frob_writable_data(&mod->init_layout, set_memory_nx); -} - -static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, - char *secstrings, struct module *mod) -{ - const unsigned long shf_wx = SHF_WRITE|SHF_EXECINSTR; - int i; - - for (i = 0; i < hdr->e_shnum; i++) { - if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) { - pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n", - mod->name, secstrings + sechdrs[i].sh_name, i); - return -ENOEXEC; - } - } - - return 0; -} - -#else /* !CONFIG_STRICT_MODULE_RWX */ -static void module_enable_nx(const struct module *mod) { } -static void module_enable_ro(const struct module *mod, bool after_init) {} -static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, - char *secstrings, struct module *mod) -{ - return 0; -} -#endif /* CONFIG_STRICT_MODULE_RWX */ - void __weak module_memfree(void *module_region) { /* diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c new file mode 100644 index 000000000000..7949dfd449c2 --- /dev/null +++ b/kernel/module/strict_rwx.c @@ -0,0 +1,85 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Module strict rwx + * + * Copyright (C) 2015 Rusty Russell + */ + +#include +#include +#include +#include +#include "internal.h" + +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); +} + +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); +} + +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); +} + +void module_enable_ro(const struct module *mod, bool after_init) +{ + if (!rodata_enabled) + return; + + set_vm_flush_reset_perms(mod->core_layout.base); + set_vm_flush_reset_perms(mod->init_layout.base); + frob_text(&mod->core_layout, set_memory_ro); + + frob_rodata(&mod->core_layout, set_memory_ro); + frob_text(&mod->init_layout, set_memory_ro); + frob_rodata(&mod->init_layout, set_memory_ro); + + if (after_init) + frob_ro_after_init(&mod->core_layout, set_memory_ro); +} + +void module_enable_nx(const struct module *mod) +{ + frob_rodata(&mod->core_layout, set_memory_nx); + frob_ro_after_init(&mod->core_layout, set_memory_nx); + frob_writable_data(&mod->core_layout, set_memory_nx); + frob_rodata(&mod->init_layout, set_memory_nx); + frob_writable_data(&mod->init_layout, set_memory_nx); +} + +int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, + char *secstrings, struct module *mod) +{ + const unsigned long shf_wx = SHF_WRITE | SHF_EXECINSTR; + int i; + + for (i = 0; i < hdr->e_shnum; i++) { + if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) { + pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n", + mod->name, secstrings + sechdrs[i].sh_name, i); + return -ENOEXEC; + } + } + + return 0; +}