From owner-freebsd-threads@freebsd.org Mon Dec 5 15:25:24 2016 Return-Path: Delivered-To: freebsd-threads@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 67DA2C6713C for ; Mon, 5 Dec 2016 15:25:24 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 57B0F1F30 for ; Mon, 5 Dec 2016 15:25:24 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from bugs.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id uB5FPO3k009391 for ; Mon, 5 Dec 2016 15:25:24 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-threads@FreeBSD.org Subject: [Bug 214540] pam_exec isn't multithreading save Date: Mon, 05 Dec 2016 15:25:24 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: threads X-Bugzilla-Version: 11.0-RELEASE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: crest@bultmann.eu X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-threads@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-threads@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Threading on FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 Dec 2016 15:25:24 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D214540 --- Comment #2 from Jan Bramkamp --- I found one case where the same issue in the Linux PAM pam_exec module broke vsftpd and vsftpd had to workaround the problem because afaik Linux lacks t= he required API to avoid this problem completely. I know that pam_exec is a ha= ck and should only be used for testing or after very careful analysis on the o= ther hand the documentation doesn't warn users about the problem and it's a nasty layering violation that blow up into the system administrators face and I d= on't want to be the poor bastard how has to debug this under time pressure. The = PAM policy isn't supposed to inject race conditions into otherwise "working" applications. Pointing to a "non-normative recommendation" won't help users bitten by this problem. My problem with this is that it's a accident waiting to happen and FreeBSD has the APIs to avoid this whole bug class. To make it worse the on= es who will run into the problem (system admins) are often incapable of debugg= ing and patching applications complex enough to use pthreads and PAM. --=20 You are receiving this mail because: You are the assignee for the bug.=