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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham 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) server-digest SHA256) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id CEEC71F47A for ; Fri, 23 Aug 2024 06:26:59 +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=aPUdIMk5; 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=Rf5IosuZ; dkim-atps=neutral DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ml.ruby-lang.org; s=mail; t=1724394417; bh=i2r61SPLCmj5VeBQ7YS0NiPY6OdZ5nUtDU4rVzBHkLo=; 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=aPUdIMk50MwHHGtWE+6guGsB0xOaGBjKfcKYmfD9SIQ3+2m1oG6J85Gt4Q8Y8MHJZ RmiXT2rO7Re3kKQrv+hjrVijiuPi7BJt61AOucMh/ELOLQ0wFntI37jf6c+Gw2IHY0 8iCxAENaaVulUjAZmfkA41X8wDK/u82e0OiavpIM= Received: from nue.mailmanlists.eu (localhost [IPv6:::1]) by nue.mailmanlists.eu (Postfix) with ESMTP id 01FAB43C93 for ; Fri, 23 Aug 2024 06:26:57 +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=Rf5IosuZ; dkim-atps=neutral Received: from s.wfbtzhsv.outbound-mail.sendgrid.net (s.wfbtzhsv.outbound-mail.sendgrid.net [159.183.224.104]) by nue.mailmanlists.eu (Postfix) with ESMTPS id 8911543BFD for ; Fri, 23 Aug 2024 06:26:45 +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=J/zopbKo0c7U02BKcosDT0QqFA7dE23Th6//ci6UzTs=; b=Rf5IosuZJo5TUOUPI4GFkUnSKXq2A7nsk70vVHXFp5J1WtWLlZ/z/oWJzAd4yYVF3pRy I57orXCBLq70Ffif74ZeUzDTeURzO3JIDUmCgVpLSO0054s52IBpu7ymHH60vYBpHigsib 1uShxa9dr45glM5cFg252sv8FnRypydVIddQ632d51HYhVwfYrWD45CheBe97WYgN/g3CF boNLKR00Fd3WfvMgmdwm1nlshDktzcKwJw6eVwcMicsJxYdc+k1TujU1RVWGqHiIOu2Y2c VUF1Tw67+ctvULoiFrvOTKjumjpAC9KntayLPdvyz4VL7u0LE1Be2PUz2NmtAX7w== Received: by recvd-57c9cdb5d8-pw4sq with SMTP id recvd-57c9cdb5d8-pw4sq-1-66C82BA3-11 2024-08-23 06:26:43.864448152 +0000 UTC m=+115818.269383780 Received: from herokuapp.com (unknown) by geopod-ismtpd-29 (SG) with ESMTP id vRN7g2TkTeSGcdQhZLA0qw for ; Fri, 23 Aug 2024 06:26:43.802 +0000 (UTC) Date: Fri, 23 Aug 2024 06:26:43 +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-Priority: Normal X-Redmine-Sender: kjtsanaktsidis 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: 95572 X-SG-EID: =?us-ascii?Q?u001=2Ehtvb0C=2FfA7uJxza5ajJoGjWf7D35DJhKe7Y94xYuv7SZnqx0qbu=2F70+zV?= =?us-ascii?Q?XRgEUZlB2KACYgzrNXwJOFqD+GI4v+xLlProPhe?= =?us-ascii?Q?RqFaaJyjkosXGeZsFE409Dl=2F3Y7JekQQbYKfv6g?= =?us-ascii?Q?PBQlteTNDEM7NNU8hAsc5xYB5S8zwIny94RwkvY?= =?us-ascii?Q?Jqvy8lU5xlN=2FS3Yz+6skL2heWRd=2F4mKQy5WdmTc?= =?us-ascii?Q?KUSzYoSu4QgbvxyE7M4Aa6j6bIyDTgNWc6UsdqM?= =?us-ascii?Q?jxh836e7mXB894t7cGVdrpaBHw=3D=3D?= To: ruby-core@ml.ruby-lang.org X-Entity-ID: u001.I8uzylDtAfgbeCOeLBYDww== Message-ID-Hash: 4HI3B5GX2ILXV5DHFXIZUZWLT6XMEPNG X-Message-ID-Hash: 4HI3B5GX2ILXV5DHFXIZUZWLT6XMEPNG 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:118936] [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: "kjtsanaktsidis (KJ Tsanaktsidis) via ruby-core" Cc: "kjtsanaktsidis (KJ Tsanaktsidis)" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Issue #20693 has been updated by kjtsanaktsidis (KJ Tsanaktsidis). I have a PR for doing this: https://github.com/ruby/ruby/pull/11403 But actually it breaks Bundler's tests, because they stub `File.writable?` in a test. I opened a fix for Bundler which needs to land first: https://github.com/rubygems/rubygems/pull/7961 ---------------------------------------- Bug #20693: Dir.tmpdir should perform a real access check before warning about writability https://bugs.ruby-lang.org/issues/20693#change-109505 * Author: kjtsanaktsidis (KJ Tsanaktsidis) * Status: Open * 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/