From owner-freebsd-bugs@freebsd.org Thu Nov 1 07:41:06 2018 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 5346410EAEBF for ; Thu, 1 Nov 2018 07:41:06 +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 E30206E360 for ; Thu, 1 Nov 2018 07:41:05 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.ysv.freebsd.org (Postfix) id A82B310EAEB1; Thu, 1 Nov 2018 07:41:05 +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 863A110EAEB0 for ; Thu, 1 Nov 2018 07:41:05 +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)) (Client CN "mxrelay.ysv.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 285EA6E35C for ; Thu, 1 Nov 2018 07:41:05 +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 60F5AAB92 for ; Thu, 1 Nov 2018 07:41:04 +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 wA17f4Y4039232 for ; Thu, 1 Nov 2018 07:41:04 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id wA17f42j039229 for bugs@FreeBSD.org; Thu, 1 Nov 2018 07:41:04 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 232878] File sealing Date: Thu, 01 Nov 2018 07:41:04 +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 Only Me X-Bugzilla-Who: contact@emersion.fr 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, 01 Nov 2018 07:41:06 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D232878 Bug ID: 232878 Summary: File sealing Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: contact@emersion.fr File sealing is a Linux-specific safety mechanism that can be used when sha= ring memory between two processes. In this scenario, one process typically calls shm_open(SHM_ANON), mmaps the result in its address space, writes interesting things in this slice of mem= ory, sends the file descriptor over a Unix socket to another process. The other process then mmaps the file descriptor to its own address space and reads t= he shared memory. Sometimes the two processes don't trust each other, for instance in the cas= e of Wayland. Bad clients may try to crash the compositor. One way to crash the compositor is to send a shared memory file descriptor = and then shrink the file. When the compositor tries to read the now-unmapped pa= rt of the file it'll receive SIGBUS. What the compositor currently does is that it handles SIGBUS and ignores it= if it's about a memory slice mmapped from IPC. Apart from being a hack, this m= akes things complicated because: * There are multiple Wayland interfaces that need to mmap a file descriptor sent over IPC. Collecting the list of IPC-mmapped regions is currently not possible with libwayland. * Since SIGBUS is global state, handling it is difficult. Some other IPC mechanisms might need to add more regions to the list. Threads make this ev= en more annoying. See https://gitlab.freedesktop.org/wayland/wayland/issues/53#note_24663 I'd like to know if there are plans to add a feature similar to file sealing (https://lwn.net/Articles/591108/) in FreeBSD. --=20 You are receiving this mail because: You are the assignee for the bug.=