From owner-freebsd-current@freebsd.org Thu Mar 21 15:55:35 2019 Return-Path: Delivered-To: freebsd-current@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 4BC4E1546467; Thu, 21 Mar 2019 15:55:35 +0000 (UTC) (envelope-from asomers@gmail.com) Received: from mail-lj1-f171.google.com (mail-lj1-f171.google.com [209.85.208.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 3D2406AD4B; Thu, 21 Mar 2019 15:55:34 +0000 (UTC) (envelope-from asomers@gmail.com) Received: by mail-lj1-f171.google.com with SMTP id k8so5727226lja.8; Thu, 21 Mar 2019 08:55:34 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=dTjtvqKPH70rNMET0lFGKYAxg78h+795UvAh5Ajs1nw=; b=lfiO4VS9JIGHv95WcXmFNYL8n5gkF6KPv1irVQF0MZzml/zhUJHyvxX7tO3vcG9u27 KaqYbldYnBubMHjZnpzPxAf3Adw5lWyoC/DWX97pY+neY9niorjbs/nIBvzdqBjx05JV rXo2QRTs34nb68i4YykCe0zscPdP6ndiSjcmx3HSk4WbGSYfcD8ZkQiHdVIVjnhl/QkM CKcUkkKLqC1UT5l0+34Ur0Gsw3sPXzaq7Koq74UWHb2nvNZ7qfkKNrVI6r6h27SLudeh 93Nd8FhyrtMc0QpKRoyGkH4zV8xFHej5+p4Nly+mWrdA/uedoi2fyRlSGCi/0DntZkFq q1ZA== X-Gm-Message-State: APjAAAX3y9OnqOuG4QCojn9W0w90G6XUhFl7CAY38nSS25C/rqbXgM2G b0SuQPX0jY2w4XKlhfZ720fPvctvVylLAjRvdaE6F95X X-Google-Smtp-Source: APXvYqwlbTRyl6PtKewy5jIDnsXJ6cv/7e9CI56xMnLOxYMw90PFIKC+JwSPVZlciNjCIUooa364RecM6xWW6czIBOM= X-Received: by 2002:a2e:1510:: with SMTP id s16mr2459281ljd.62.1553183726579; Thu, 21 Mar 2019 08:55:26 -0700 (PDT) MIME-Version: 1.0 References: <20190321154817.2lgwjzl4o2urlmdw@mutt-hbsd> In-Reply-To: <20190321154817.2lgwjzl4o2urlmdw@mutt-hbsd> From: Alan Somers Date: Thu, 21 Mar 2019 09:55:15 -0600 Message-ID: Subject: Re: HEAD'S UP: fusefs sysctls going away To: Shawn Webb Cc: FreeBSD CURRENT , freebsd-fs Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 3D2406AD4B X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; spf=pass (mx1.freebsd.org: domain of asomers@gmail.com designates 209.85.208.171 as permitted sender) smtp.mailfrom=asomers@gmail.com X-Spamd-Result: default: False [-3.33 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-0.998,0]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; R_SPF_ALLOW(-0.20)[+ip4:209.85.128.0/17]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[text/plain]; MIME_TRACE(0.00)[0:+]; DMARC_NA(0.00)[freebsd.org]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TO_DN_ALL(0.00)[]; MX_GOOD(-0.01)[cached: alt3.gmail-smtp-in.l.google.com]; NEURAL_HAM_SHORT(-0.01)[-0.009,0]; RCVD_IN_DNSWL_NONE(0.00)[171.208.85.209.list.dnswl.org : 127.0.5.0]; RCVD_TLS_LAST(0.00)[]; FORGED_SENDER(0.30)[asomers@freebsd.org,asomers@gmail.com]; R_DKIM_NA(0.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:209.85.128.0/17, country:US]; FROM_NEQ_ENVFROM(0.00)[asomers@freebsd.org,asomers@gmail.com]; IP_SCORE(-1.31)[ip: (-0.51), ipnet: 209.85.128.0/17(-3.86), asn: 15169(-2.12), country: US(-0.07)]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Mar 2019 15:55:35 -0000 On Thu, Mar 21, 2019 at 9:49 AM Shawn Webb wrote: > > Hey Alan, > > Thank you very much for your work in maintaining fusefs. I only use > fusefs in very limited circumstances, so take what I'm about to say > with a grain of salt. > > On Thu, Mar 21, 2019 at 09:43:07AM -0600, Alan Somers wrote: > > fusefs has several sysctl knobs that seem to be workarounds for bugs > > in particular fuse daemons. However, there is no indication as to > > which those daemons are, neither in the code nor in SVN. All of the > > workarounds are at least 6.5 years old, so the original bugs may have > > been fixed already. Since the original bugs aren't documented, I > > consider these workarounds to be unmaintainable, and I'm planning to > > delete them unless anybody objects. Please pipe up if you still use > > them! > > > > vfs.fusefs.mmap_enable: If non-zero, and data_cache_mode is also > > non-zero, enable mmap(2) of FUSE files > > I'm curious if the security impacts of removing the toggle to disable > mmap support for fusefs. Is there a per-fusefs replacement for > mmap_enable? From a security perspective, it would be nice to keep the > ability to disable mapping of files mounted on a fusefs. As a matter of fact, there are three other ways to disable mmap: 1) Set vfs.fusefs.data_cache_mode=0. This completely disables caching file data, which precludes mmap. 2) Use the undocumented -o no_datacache mount option, which does the same thing on a per-mount basis. 3) Use the undocumented -o no_mmap mount option, which disables mmap on a per-mount basis. Are you aware of any general security problems with using mmap? Anything that would apply to fusefs but not other filesystems? -Alan