From mboxrd@z Thu Jan 1 00:00:00 1970 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 C6B88C433F5 for ; Wed, 13 Apr 2022 13:50:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235990AbiDMNxN (ORCPT ); Wed, 13 Apr 2022 09:53:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235960AbiDMNw0 (ORCPT ); Wed, 13 Apr 2022 09:52:26 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A14D2655A for ; Wed, 13 Apr 2022 06:50:04 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 02A26B824E7 for ; Wed, 13 Apr 2022 13:50:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCBB5C385AF; Wed, 13 Apr 2022 13:49:58 +0000 (UTC) From: Catalin Marinas To: Andrew Morton , Christoph Hellwig , Lennart Poettering , =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= Cc: Will Deacon , Alexander Viro , Eric Biederman , Kees Cook , Szabolcs Nagy , Mark Brown , Jeremy Linton , Topi Miettinen , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-abi-devel@lists.sourceforge.net Subject: [PATCH RFC 3/4] fs/binfmt_elf: Tell user-space about the DENY_WRITE_EXEC personality flag Date: Wed, 13 Apr 2022 14:49:45 +0100 Message-Id: <20220413134946.2732468-4-catalin.marinas@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220413134946.2732468-1-catalin.marinas@arm.com> References: <20220413134946.2732468-1-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since personality() accepts any flags and does not mask out any unknown bits, inform user space that such personality flag is supported via an AT_FLAGS_DENY_WRITE_EXEC flag. Signed-off-by: Catalin Marinas Cc: Alexander Viro Cc: Eric Biederman Cc: Kees Cook Cc: Christoph Hellwig --- fs/binfmt_elf.c | 2 ++ include/uapi/linux/binfmts.h | 4 ++++ 2 files changed, 6 insertions(+) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 6556e13ed95f..4e6cba1f67ee 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -265,6 +265,8 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec, NEW_AUX_ENT(AT_BASE, interp_load_addr); if (bprm->interp_flags & BINPRM_FLAGS_PRESERVE_ARGV0) flags |= AT_FLAGS_PRESERVE_ARGV0; + if (IS_ENABLED(CONFIG_ARCH_ENABLE_DENY_WRITE_EXEC)) + flags |= AT_FLAGS_DENY_WRITE_EXEC; NEW_AUX_ENT(AT_FLAGS, flags); NEW_AUX_ENT(AT_ENTRY, e_entry); NEW_AUX_ENT(AT_UID, from_kuid_munged(cred->user_ns, cred->uid)); diff --git a/include/uapi/linux/binfmts.h b/include/uapi/linux/binfmts.h index c6f9450efc12..304bbb30264c 100644 --- a/include/uapi/linux/binfmts.h +++ b/include/uapi/linux/binfmts.h @@ -22,4 +22,8 @@ struct pt_regs; #define AT_FLAGS_PRESERVE_ARGV0_BIT 0 #define AT_FLAGS_PRESERVE_ARGV0 (1 << AT_FLAGS_PRESERVE_ARGV0_BIT) +/* support for DENY_WRITE_EXEC personality flag */ +#define AT_FLAGS_DENY_WRITE_EXEC_BIT 1 +#define AT_FLAGS_DENY_WRITE_EXEC (1 << AT_FLAGS_DENY_WRITE_EXEC_BIT) + #endif /* _UAPI_LINUX_BINFMTS_H */