From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on starla X-Spam-Level: X-Spam-Status: No, score=0.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_BL_SPAMCOP_NET,SPF_HELO_PASS, SPF_PASS autolearn=no autolearn_force=no version=3.4.6 Received: from nue.mailmanlists.eu (nue.mailmanlists.eu [94.130.110.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id CE6271F4BE for ; Mon, 21 Oct 2024 10:06:46 +0000 (UTC) Authentication-Results: dcvr.yhbt.net; dkim=pass (1024-bit key; unprotected) header.d=ml.ruby-lang.org header.i=@ml.ruby-lang.org header.a=rsa-sha256 header.s=mail header.b=Vy4NPKna; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ruby-lang.org header.i=@ruby-lang.org header.a=rsa-sha256 header.s=s1 header.b=MRyCrbgG; dkim-atps=neutral DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ml.ruby-lang.org; s=mail; t=1729505204; bh=/bJf4LbjJX+h7Zbx/QwrTfh2egLtgzxySHnT/u6HlQo=; h=Date:References:To:Reply-To:Subject:List-Id:List-Archive: List-Help:List-Owner:List-Post:List-Subscribe:List-Unsubscribe: From:Cc:From; b=Vy4NPKnaVzTPxpwn0Lh9Lhco5M9wHl/yuqd9uYOdPF0ZxjWlIrC6xGtrU2JnZuJk9 IUG4BSwXoFTDRkkt9YLr4bOAUB3QWieBgFQIg+3+ku8DQfHs93oDLCcvrQkk1RZMOb s18duGNe4W5fOpm9Jkad1r6aPo4W4wVwg8N0qKoM= Received: from nue.mailmanlists.eu (localhost [IPv6:::1]) by nue.mailmanlists.eu (Postfix) with ESMTP id ADA7A44BA8 for ; Mon, 21 Oct 2024 10:06:44 +0000 (UTC) Authentication-Results: nue.mailmanlists.eu; dkim=pass (2048-bit key; unprotected) header.d=ruby-lang.org header.i=@ruby-lang.org header.a=rsa-sha256 header.s=s1 header.b=MRyCrbgG; dkim-atps=neutral Received: from s.wrqvwxzv.outbound-mail.sendgrid.net (s.wrqvwxzv.outbound-mail.sendgrid.net [149.72.154.232]) by nue.mailmanlists.eu (Postfix) with ESMTPS id F198B449D6 for ; Mon, 21 Oct 2024 10:06:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ruby-lang.org; h=from:references:subject:mime-version:content-type: content-transfer-encoding:list-id:to:cc:content-type:from:subject:to; s=s1; bh=K+0bBgiLj06wIbEgpFwOqPbUfGpgspNgKZXIIDELUOw=; b=MRyCrbgGGdXzWBL27n+jXZjaLJmu/B05Cc8cBfAUxeaHZ8jqCtJaVLwN0zuXFfgduGTp 7pNwSD+r4q0cFhvWWEDlN83obR3iP5UOnx9IVoj9fq/hHx8gsmfiIVD3KVz65VDDgiJFII vvwlXSYPy22PZ1eynqqyWjVuxNRPcBmDhiVN99ejYgBax52zbcPJkc37LqDg3yya9WXLle bqAkFfmE50XH/zaQge/HHMJZSkU1tOQ6rdc1v81eXISBrn+8QlaFN8yk4HDfm+qezP6tjD pf4i0g9A8F5ey3mZ6tK0U3TpC2p0bSxrnYgbVILIV4m7zBXRy7fGjgRErfvp2dGg== Received: by recvd-7cc7f7d978-qwpgn with SMTP id recvd-7cc7f7d978-qwpgn-1-671627A8-A 2024-10-21 10:06:32.134544635 +0000 UTC m=+3341420.326337384 Received: from herokuapp.com (unknown) by geopod-ismtpd-37 (SG) with ESMTP id LdEGXwFwTVOcjy1J1rUnEg for ; Mon, 21 Oct 2024 10:06:32.118 +0000 (UTC) Date: Mon, 21 Oct 2024 10:06:32 +0000 (UTC) Message-ID: References: Mime-Version: 1.0 X-Redmine-Project: ruby-master X-Redmine-Issue-Tracker: Bug X-Redmine-Issue-Id: 20693 X-Redmine-Issue-Author: kjtsanaktsidis X-Redmine-Issue-Assignee: akr X-Redmine-Issue-Priority: Normal X-Redmine-Sender: akr X-Mailer: Redmine X-Redmine-Host: bugs.ruby-lang.org X-Redmine-Site: Ruby Issue Tracking System X-Auto-Response-Suppress: All Auto-Submitted: auto-generated X-Redmine-MailingListIntegration-Message-Ids: 96202 X-SG-EID: =?us-ascii?Q?u001=2EjUYdomjR8qg=2FmRRJiw9jcD8=2F=2Fg2V+YCwM42AbEffAz+piO1ivD2ssVdIf?= =?us-ascii?Q?UsAvXwsSNeFNBeVO12+lrvx7XL=2FC4Qcpj6vGkBJ?= =?us-ascii?Q?aS9IWcLFYuTzyebP8r=2FMfNEJOGxZC4vDSfb4yZh?= =?us-ascii?Q?ZXLyXTUxB1uudhl3fkkNj+oYuB5YR8QXhCeP9uf?= =?us-ascii?Q?tyn1lY6FTVmBxiSWRgiZYSlPFKt3sCAg+ZQxMb3?= =?us-ascii?Q?lxqYmm0VW45+u7bcYEDcr75D+oBnvSO5RY=2FYErQ?= =?us-ascii?Q?u2K9?= To: ruby-core@ml.ruby-lang.org X-Entity-ID: u001.I8uzylDtAfgbeCOeLBYDww== Message-ID-Hash: K26WAGO4NGKMURMTP3ZNPU3SE5QHYKWD X-Message-ID-Hash: K26WAGO4NGKMURMTP3ZNPU3SE5QHYKWD X-MailFrom: bounces+313651-b711-ruby-core=ml.ruby-lang.org@em5188.ruby-lang.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.9 Precedence: list Reply-To: Ruby developers Subject: [ruby-core:119568] [Ruby master Bug#20693] Dir.tmpdir should perform a real access check before warning about writability List-Id: Ruby developers Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: From: "akr (Akira Tanaka) via ruby-core" Cc: "akr (Akira Tanaka)" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Issue #20693 has been updated by akr (Akira Tanaka). OK. Thank you. ---------------------------------------- Bug #20693: Dir.tmpdir should perform a real access check before warning about writability https://bugs.ruby-lang.org/issues/20693#change-110182 * Author: kjtsanaktsidis (KJ Tsanaktsidis) * Status: Open * Assignee: akr (Akira Tanaka) * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- The code in `Dir.tmpdir` attempts to warn the user if their temp directory is deficient for some reason: ```ruby case when !stat.directory? warn "#{name} is not a directory: #{dir}" when !stat.writable? warn "#{name} is not writable: #{dir}" when stat.world_writable? && !stat.sticky? warn "#{name} is world-writable: #{dir}" else break dir end ``` This check for writability is looking at the user/group/world access bits on the stat output, and determining if the user running Ruby is allowed to write to the temp directory based on that. However, modern operating systems contain other mechanisms apart from the user/group/world bits which can grant access to a directory that would otherwise be denied, or vice versa. Things like: * Posix ACL's * Linux's capabilities like CAP_DAC_OVERRIDE * Linux Security Modules like SELinux or AppArmor * Syscall filters like Linux's seccomp * Granular capability systems like FreeBSD's Capsicum * OpenBSD's pledge and unveil * Windows too has a rich ACL system for controlling filesystem access To address this, we should call `File.writable?` instead of `stat.writable?`, which asks the system whether the file is writable using the `euidaccess()` function if available. On Linux/glibc, at least, this will issue an `access(2)` syscall, and the Kernel can take all of the above into account. n.b. if Ruby is running as suid, then glibc currently will NOT ask the kernel to perform the access check in `euidaccess()`, and instead does a similar thing to what `Stat#writable?` does (https://github.com/bminor/glibc/blob/7f04bb4e49413bd57ac3215f3480b09ae7131968/sysdeps/posix/euidaccess.c#L159-L162). This is because of the relatively new `faccessat2(2)` syscall is required to do this properly, and there is some ecosystem issues with leveraging this by default (e.g. https://bugzilla.redhat.com/show_bug.cgi?id=1900021). Since running Ruby as suid is probably a very bad idea anyway, and the glibc implementation isn't any worse than the `Stat#writable?` one, this seems OK though. -- https://bugs.ruby-lang.org/ ______________________________________________ ruby-core mailing list -- ruby-core@ml.ruby-lang.org To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/