From patchwork Mon Oct 11 15:25:37 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 12550327 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 9866EC433FE for ; Mon, 11 Oct 2021 15:26:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 771DB60F6E for ; Mon, 11 Oct 2021 15:26:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238419AbhJKP2p (ORCPT ); Mon, 11 Oct 2021 11:28:45 -0400 Received: from pegase2.c-s.fr ([93.17.235.10]:52677 "EHLO pegase2.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238231AbhJKP2n (ORCPT ); Mon, 11 Oct 2021 11:28:43 -0400 Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4HSjM41DLlz9sV4; Mon, 11 Oct 2021 17:26:40 +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 fpQr6HfP7u29; Mon, 11 Oct 2021 17:26:40 +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 4HSjM271n6z9sTs; Mon, 11 Oct 2021 17:26:38 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id CC8AA8B773; Mon, 11 Oct 2021 17:26:38 +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 jI_UH71UA1dc; Mon, 11 Oct 2021 17:26:38 +0200 (CEST) Received: from PO20335.IDSI0.si.c-s.fr (unknown [172.25.230.103]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 4A8238B77A; Mon, 11 Oct 2021 17:26:38 +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 19BFQWd31585043 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Mon, 11 Oct 2021 17:26:32 +0200 Received: (from chleroy@localhost) by PO20335.IDSI0.si.c-s.fr (8.16.1/8.16.1/Submit) id 19BFQWRh1585042; Mon, 11 Oct 2021 17:26:32 +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 v1 10/10] lkdtm: Fix execute_[user]_location() Date: Mon, 11 Oct 2021 17:25:37 +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=1633965929; l=3205; s=20211009; h=from:subject:message-id; bh=l9VMW9X0cJdJ5G39QvOQSX7TaMvTqTcPjFZvPR3zBnY=; b=jicnpEgsrfjH5zYpDhYjzje61oqpOOuq/IuppB5jOn2Ba0Gd0x1VsCW6/z7XdMGhv8A23JZri38f B8zYR3a+B6WB1RVyyaaI9RtV86aWs3LS+2H/2P5Ya4RB7CP/W3A1 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 | 45 +++++++++++++++++++++++++++++++------- 1 file changed, 37 insertions(+), 8 deletions(-) diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c index da16564e1ecd..1d03cd44c21d 100644 --- a/drivers/misc/lkdtm/perms.c +++ b/drivers/misc/lkdtm/perms.c @@ -44,19 +44,42 @@ static noinline void do_overwritten(void) return; } +static void *setup_function_descriptor(funct_descr_t *fdesc, void *dst) +{ + int err; + + if (!__is_defined(HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR)) + return dst; + + err = copy_from_kernel_nofault(fdesc, do_nothing, sizeof(*fdesc)); + if (err < 0) + return ERR_PTR(err); + + fdesc->addr = (unsigned long)dst; + barrier(); + + return fdesc; +} + static noinline void execute_location(void *dst, bool write) { - void (*func)(void) = dst; + void (*func)(void); + funct_descr_t fdesc; + void *do_nothing_text = dereference_symbol_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); + func = setup_function_descriptor(&fdesc, dst); + if (IS_ERR(func)) + return; + + pr_info("attempting bad execution at %px\n", dst); func(); pr_err("FAIL: func returned\n"); } @@ -66,16 +89,22 @@ static void execute_user_location(void *dst) int copied; /* Intentionally crossing kernel/user memory boundary. */ - void (*func)(void) = dst; + void (*func)(void); + funct_descr_t fdesc; + void *do_nothing_text = dereference_symbol_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); + func = setup_function_descriptor(&fdesc, dst); + if (IS_ERR(func)) + return; + + pr_info("attempting bad execution at %px\n", dst); func(); pr_err("FAIL: func returned\n"); }