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 X-Spam-Level: X-Spam-Status: No, score=-9.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DD874C433E1 for ; Fri, 5 Jun 2020 16:00:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BCE6820870 for ; Fri, 5 Jun 2020 16:00:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="AYM1SME2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727780AbgFEQAU (ORCPT ); Fri, 5 Jun 2020 12:00:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36718 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727024AbgFEQAU (ORCPT ); Fri, 5 Jun 2020 12:00:20 -0400 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 11E02C08C5C2 for ; Fri, 5 Jun 2020 09:00:20 -0700 (PDT) Received: by mail-pg1-x542.google.com with SMTP id u5so5318111pgn.5 for ; Fri, 05 Jun 2020 09:00:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=yOHx3JtZHl4XxOR183MPHxc1YyQEXr9//zjD6wPWK5c=; b=AYM1SME2Yfp8Xp3XxiCuKbsb/mxLno+9x6Tvnx0AKRTBFR+Vyg+D0jJsDdO6B008gJ j5cR/0Kki2xB3IEr7YyNhWdFsN1hYKuv0eVUgkVN7P1iFoWJU4m2y+AVWl/YWwRjCuX0 L63p9QE40scOglygoynUT1EFudt2cy5+UMbec= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=yOHx3JtZHl4XxOR183MPHxc1YyQEXr9//zjD6wPWK5c=; b=d+vyJE6QQeKzjwcFSqaQ3fyjq042XsQqhrPDlQwagNTSz6mv+/cePt/x6RcAiEeXJd 8iBOKlNZbozw5kdMUtvV4nAjpQFR0gpVtbx+c1NJg7kSRxuazz8dzZPF+EM1T3SaX94E /1SrenDK7z5qqRP3A5XZKvKxRRvp7yP6TfcA3Z1GlbWms/VCyyniZrejCWyP5ekck6CP v/XgTSUFuLm/jwVp3uX8psOO4aakfPJZneMFvu3GaXLModQR0NlFpvfPptLpJxSH8a4F 53jGWfG310fWy6oOxs/QJYTdxDKxAFvH1P1cqA1mKKlW8hEBbgyiT2vEgJxoSh0QIJsJ qVyg== X-Gm-Message-State: AOAM532EdgWJ8EouM4RE4NT0lCcCXX+4bghtDzdGc7ryUb2f5EL1sS8K 7dW5XI5PLu1cknlNad1F0MTPQQ== X-Google-Smtp-Source: ABdhPJyVjuUcteaqY/mcT8ScT3S6QTSiJYt9wnTPuDWOo6anaUmiM00CCJIUs5IvLlBc1Bo5bes43g== X-Received: by 2002:a63:f14a:: with SMTP id o10mr10411918pgk.216.1591372819568; Fri, 05 Jun 2020 09:00:19 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id 10sm68354pfn.6.2020.06.05.09.00.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Jun 2020 09:00:18 -0700 (PDT) From: Kees Cook To: Andrew Morton Cc: Kees Cook , Alexander Viro , Aleksa Sarai , Christian Brauner , Dmitry Vyukov , Eric Biggers , Tetsuo Handa , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 3/3] exec: Move path_noexec() check earlier Date: Fri, 5 Jun 2020 09:00:13 -0700 Message-Id: <20200605160013.3954297-4-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200605160013.3954297-1-keescook@chromium.org> References: <20200605160013.3954297-1-keescook@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org The path_noexec() check, like the regular file check, was happening too late, letting LSMs see impossible execve()s. Check it earlier as well in may_open() and collect the redundant fs/exec.c path_noexec() test under the same robustness comment as the S_ISREG() check. My notes on the call path, and related arguments, checks, etc: do_open_execat() struct open_flags open_exec_flags = { .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, .acc_mode = MAY_EXEC, ... do_filp_open(dfd, filename, open_flags) path_openat(nameidata, open_flags, flags) file = alloc_empty_file(open_flags, current_cred()); do_open(nameidata, file, open_flags) may_open(path, acc_mode, open_flag) /* new location of MAY_EXEC vs path_noexec() test */ inode_permission(inode, MAY_OPEN | acc_mode) security_inode_permission(inode, acc_mode) vfs_open(path, file) do_dentry_open(file, path->dentry->d_inode, open) security_file_open(f) open() /* old location of path_noexec() test */ Signed-off-by: Kees Cook --- fs/exec.c | 12 ++++-------- fs/namei.c | 4 ++++ 2 files changed, 8 insertions(+), 8 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 2b708629dcd6..7ac50a260df3 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -145,10 +145,8 @@ SYSCALL_DEFINE1(uselib, const char __user *, library) * and check again at the very end too. */ error = -EACCES; - if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode))) - goto exit; - - if (path_noexec(&file->f_path)) + if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) || + path_noexec(&file->f_path))) goto exit; fsnotify_open(file); @@ -871,10 +869,8 @@ static struct file *do_open_execat(int fd, struct filename *name, int flags) * and check again at the very end too. */ err = -EACCES; - if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode))) - goto exit; - - if (path_noexec(&file->f_path)) + if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) || + path_noexec(&file->f_path))) goto exit; err = deny_write_access(file); diff --git a/fs/namei.c b/fs/namei.c index 0a759b68d66e..41e6fed8ce69 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2849,6 +2849,10 @@ static int may_open(const struct path *path, int acc_mode, int flag) return -EACCES; flag &= ~O_TRUNC; break; + case S_IFREG: + if ((acc_mode & MAY_EXEC) && path_noexec(path)) + return -EACCES; + break; } error = inode_permission(inode, MAY_OPEN | acc_mode); -- 2.25.1