From patchwork Thu Oct 14 05:50:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 12557819 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7099C433EF for ; Thu, 14 Oct 2021 06:25:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B0F6661152 for ; Thu, 14 Oct 2021 06:25:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230209AbhJNG1T (ORCPT ); Thu, 14 Oct 2021 02:27:19 -0400 Received: from pegase2.c-s.fr ([93.17.235.10]:45337 "EHLO pegase2.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230255AbhJNG1N (ORCPT ); Thu, 14 Oct 2021 02:27:13 -0400 Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4HVK9h5Hh9z9sSb; Thu, 14 Oct 2021 08:24:08 +0200 (CEST) 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 WkfQKbTlHhED; Thu, 14 Oct 2021 08:24:08 +0200 (CEST) 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 4HVK9Z4pzWz9sSm; Thu, 14 Oct 2021 08:24:02 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 8F2E88B788; Thu, 14 Oct 2021 08:24:02 +0200 (CEST) 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 fQzu50CkfBZv; Thu, 14 Oct 2021 08:24:02 +0200 (CEST) Received: from PO20335.IDSI0.si.c-s.fr (unknown [192.168.202.231]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 3589A8B763; Thu, 14 Oct 2021 08:24:02 +0200 (CEST) Received: from PO20335.IDSI0.si.c-s.fr (localhost [127.0.0.1]) by PO20335.IDSI0.si.c-s.fr (8.16.1/8.16.1) with ESMTPS id 19E5oQgm2266042 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Thu, 14 Oct 2021 07:50:26 +0200 Received: (from chleroy@localhost) by PO20335.IDSI0.si.c-s.fr (8.16.1/8.16.1/Submit) id 19E5oQd22266041; Thu, 14 Oct 2021 07:50:26 +0200 X-Authentication-Warning: PO20335.IDSI0.si.c-s.fr: chleroy set sender to christophe.leroy@csgroup.eu using -f From: Christophe Leroy To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Andrew Morton , "James E.J. Bottomley" , Helge Deller , Arnd Bergmann , Kees Cook , Greg Kroah-Hartman Cc: Christophe Leroy , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-ia64@vger.kernel.org, linux-parisc@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 12/13] lkdtm: Fix execute_[user]_location() Date: Thu, 14 Oct 2021 07:50:01 +0200 Message-Id: X-Mailer: git-send-email 2.31.1 In-Reply-To: References: MIME-Version: 1.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1634190596; l=3389; s=20211009; h=from:subject:message-id; bh=/NBloWboE7tAULPmP7BOXtz6OWoNUEZRrAB3xKixwdU=; b=4flPamtTkvGPUtcU0sHwSxv0NG8ktt3lwWa8/xTZBJ5IOlZl9vgP0rMEQGn4vB7FTUGMNKDCY1vl jjnZDPU5Bkp23Hqfy/0Db4Tf8vg3xiRSXNuPYEhC+6C4yEdRDVTL X-Developer-Key: i=christophe.leroy@csgroup.eu; a=ed25519; pk=HIzTzUj91asvincQGOFx6+ZF5AoUuP9GdOtQChs7Mm0= Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org execute_location() and execute_user_location() intent to copy do_nothing() text and execute it at a new location. However, at the time being it doesn't copy do_nothing() function but do_nothing() function descriptor which still points to the original text. So at the end it still executes do_nothing() at its original location allthough using a copied function descriptor. So, fix that by really copying do_nothing() text and build a new function descriptor by copying do_nothing() function descriptor and updating the target address with the new location. Also fix the displayed addresses by dereferencing do_nothing() function descriptor. Signed-off-by: Christophe Leroy --- drivers/misc/lkdtm/perms.c | 25 +++++++++++++++++++++---- include/asm-generic/sections.h | 5 +++++ 2 files changed, 26 insertions(+), 4 deletions(-) diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c index 5266dc28df6e..96b3ebfcb8ed 100644 --- a/drivers/misc/lkdtm/perms.c +++ b/drivers/misc/lkdtm/perms.c @@ -44,19 +44,32 @@ static noinline void do_overwritten(void) return; } +static void *setup_function_descriptor(func_desc_t *fdesc, void *dst) +{ + memcpy(fdesc, do_nothing, sizeof(*fdesc)); + fdesc->addr = (unsigned long)dst; + barrier(); + + return fdesc; +} + static noinline void execute_location(void *dst, bool write) { void (*func)(void) = dst; + func_desc_t fdesc; + void *do_nothing_text = dereference_function_descriptor(do_nothing); - pr_info("attempting ok execution at %px\n", do_nothing); + pr_info("attempting ok execution at %px\n", do_nothing_text); do_nothing(); if (write == CODE_WRITE) { - memcpy(dst, do_nothing, EXEC_SIZE); + memcpy(dst, do_nothing_text, EXEC_SIZE); flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE); } pr_info("attempting bad execution at %px\n", func); + if (have_function_descriptors()) + func = setup_function_descriptor(&fdesc, dst); func(); pr_err("FAIL: func returned\n"); } @@ -67,15 +80,19 @@ static void execute_user_location(void *dst) /* Intentionally crossing kernel/user memory boundary. */ void (*func)(void) = dst; + func_desc_t fdesc; + void *do_nothing_text = dereference_function_descriptor(do_nothing); - pr_info("attempting ok execution at %px\n", do_nothing); + pr_info("attempting ok execution at %px\n", do_nothing_text); do_nothing(); - copied = access_process_vm(current, (unsigned long)dst, do_nothing, + copied = access_process_vm(current, (unsigned long)dst, do_nothing_text, EXEC_SIZE, FOLL_WRITE); if (copied < EXEC_SIZE) return; pr_info("attempting bad execution at %px\n", func); + if (have_function_descriptors()) + func = setup_function_descriptor(&fdesc, dst); func(); pr_err("FAIL: func returned\n"); } diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h index 76163883c6ff..d225318538bd 100644 --- a/include/asm-generic/sections.h +++ b/include/asm-generic/sections.h @@ -70,6 +70,11 @@ typedef struct { } func_desc_t; #endif +static inline bool have_function_descriptors(void) +{ + return __is_defined(HAVE_FUNCTION_DESCRIPTORS); +} + /* random extra sections (if any). Override * in asm/sections.h */ #ifndef arch_is_kernel_text