From owner-freebsd-bugs@freebsd.org Thu Mar 28 01:59:36 2019 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 682C51564FC7 for ; Thu, 28 Mar 2019 01:59:36 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id A7D8F74F62 for ; Thu, 28 Mar 2019 01:59:35 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.ysv.freebsd.org (Postfix) id 5E01C1564FC6; Thu, 28 Mar 2019 01:59:35 +0000 (UTC) Delivered-To: bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 20BB01564FC5 for ; Thu, 28 Mar 2019 01:59:35 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.ysv.freebsd.org (mxrelay.ysv.freebsd.org [IPv6:2001:1900:2254:206a::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.ysv.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 94D3474F60 for ; Thu, 28 Mar 2019 01:59:34 +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 mxrelay.ysv.freebsd.org (Postfix) with ESMTPS id CBE211BDA9 for ; Thu, 28 Mar 2019 01:59:33 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id x2S1xXbO018912 for ; Thu, 28 Mar 2019 01:59:33 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id x2S1xXaj018911 for bugs@FreeBSD.org; Thu, 28 Mar 2019 01:59:33 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 236844] [FUSEFS] fusefs should send FUSE_OPEN for every open(2) Date: Thu, 28 Mar 2019 01:59:33 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: asomers@FreeBSD.org X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter Message-ID: 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-bugs@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 28 Mar 2019 01:59:36 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D236844 Bug ID: 236844 Summary: [FUSEFS] fusefs should send FUSE_OPEN for every open(2) Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Many People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: asomers@FreeBSD.org The design of the fuse protocol requires the client to send FUSE_OPEN every time that a file is opened. That's necessary for two reasons: 1) Permission checks are handled by the server 2) The server may need to know what open(2) flags were used with each open = and with subsequent operations associated with that file descriptor. It uses t= he fh parameter to track that. However, FreeBSD's fuse module takes a shortcut: it tries to reuse the same= fh for multiple files, as long as their open flags were the same. But this approach has multiple problems: 1) It only checks the first 2 bits of the open flags. To do otherwise would take a prohibitive amount of RAM (bug 236340). 2) It will reuse file handles between multiple different processes as long = as their open flags are the same, defeating the ability of the daemon to valid= ate permissions. 3) It isn't even ok to reuse filehandles within the same process for opens = that have the exact same flags. The daemon might be doing something weird like treating each file descriptor as a socket or something. It's allowed to do that. This bug may be very hard to solve. The problem is that our vnode ops are = all file-agnostic. VOP_WRITE, for example, doesn't know what file descriptor w= as used to initiate a write. We could solve the problem by implementing a cus= tom fileops structure for fuse. However, that may require re-implementing most= of kern/vfs_vnops.c just for fuse. Or, we could add a struct file* argument to most VOPs, but that would probably meet with some justified resistance. Or= , we could always operate as if the default_permissions mount option were used a= nd do all privilege checking in the kernel. Then we could get away with only sending FUSE_OPEN the first time that a file is opened. Of course, we would need to actually make default_permissions work first, but that's another bu= g... --=20 You are receiving this mail because: You are the assignee for the bug.=