From patchwork Tue Feb 15 12:41:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 12747065 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 BE7DDC433F5 for ; Tue, 15 Feb 2022 12:50:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237926AbiBOMuz (ORCPT ); Tue, 15 Feb 2022 07:50:55 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:52290 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238030AbiBOMus (ORCPT ); Tue, 15 Feb 2022 07:50:48 -0500 Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 19A9D28E29; Tue, 15 Feb 2022 04:50:39 -0800 (PST) Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4Jyggr1hh1z9sT6; Tue, 15 Feb 2022 13:41:28 +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 cv3W_86XngO4; Tue, 15 Feb 2022 13:41:28 +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 4Jyggn2JSXz9sSM; Tue, 15 Feb 2022 13:41:25 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 3E5878B776; Tue, 15 Feb 2022 13:41:25 +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 WPscdcyoI9n4; Tue, 15 Feb 2022 13:41:25 +0100 (CET) Received: from PO20335.IDSI0.si.c-s.fr (unknown [192.168.6.174]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 734EC8B77A; Tue, 15 Feb 2022 13:41:24 +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 21FCfHgj080653 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Tue, 15 Feb 2022 13:41:17 +0100 Received: (from chleroy@localhost) by PO20335.IDSI0.si.c-s.fr (8.17.1/8.17.1/Submit) id 21FCfHjQ080652; Tue, 15 Feb 2022 13:41:17 +0100 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 v4 12/13] lkdtm: Fix execute_[user]_location() Date: Tue, 15 Feb 2022 13:41:07 +0100 Message-Id: <4055839683d8d643cd99be121f4767c7c611b970.1644928018.git.christophe.leroy@csgroup.eu> 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=1644928861; l=3354; s=20211009; h=from:subject:message-id; bh=SBdxSdBVzsHERnTdj4a/2I5p8K4EgN/GiDvmLHXoddo=; b=CtdTmajv7K3548edlO2OkA8rck/ZUy1Fo6Cid1dcSAQa2dmYUxkof4l0Oboco2WlOelKf85Jyrxm TRcmdjTxAS1FS8scsp1XTM7ZAKTEg0azI8gXhuv/WgIRZioDRvQr 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 Acked-by: Kees Cook --- drivers/misc/lkdtm/perms.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c index 035fcca441f0..1cf24c4a79e9 100644 --- a/drivers/misc/lkdtm/perms.c +++ b/drivers/misc/lkdtm/perms.c @@ -44,19 +44,34 @@ static noinline void do_overwritten(void) return; } +static void *setup_function_descriptor(func_desc_t *fdesc, void *dst) +{ + if (!have_function_descriptors()) + return 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; + void (*func)(void); + 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); + pr_info("attempting bad execution at %px\n", dst); + func = setup_function_descriptor(&fdesc, dst); func(); pr_err("FAIL: func returned\n"); } @@ -66,16 +81,19 @@ static void execute_user_location(void *dst) int copied; /* Intentionally crossing kernel/user memory boundary. */ - void (*func)(void) = dst; + void (*func)(void); + 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); + pr_info("attempting bad execution at %px\n", dst); + func = setup_function_descriptor(&fdesc, dst); func(); pr_err("FAIL: func returned\n"); } @@ -153,7 +171,8 @@ void lkdtm_EXEC_VMALLOC(void) void lkdtm_EXEC_RODATA(void) { - execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS); + execute_location(dereference_function_descriptor(lkdtm_rodata_do_nothing), + CODE_AS_IS); } void lkdtm_EXEC_USERSPACE(void)