From nobody Thu Nov 23 16:13:26 2023 X-Original-To: freebsd-current@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4SbjpX6ktnz51plF for ; Thu, 23 Nov 2023 16:13:40 +0000 (UTC) (envelope-from rick.macklem@gmail.com) Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1D4" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4SbjpX0q0wz4VkV; Thu, 23 Nov 2023 16:13:40 +0000 (UTC) (envelope-from rick.macklem@gmail.com) Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20230601 header.b=eJvmC81g; spf=pass (mx1.freebsd.org: domain of rick.macklem@gmail.com designates 2607:f8b0:4864:20::102d as permitted sender) smtp.mailfrom=rick.macklem@gmail.com; dmarc=pass (policy=none) header.from=gmail.com Received: by mail-pj1-x102d.google.com with SMTP id 98e67ed59e1d1-2809b4d648bso866476a91.2; Thu, 23 Nov 2023 08:13:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1700756018; x=1701360818; darn=freebsd.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=vh2UKPMNx1L/5N+6LNgkvUvX17L29P0s2Gceuwy/h9o=; b=eJvmC81gx3WMLrLUYGtWPRjVycsOBerHCcibQJHmPVF1Ai6YD+TZ82ltN/J650OD8U Fh6p/XHQ+qfnCQnoWzKnXgfhIN3GDvyF1FYPeR46ED2kdVLf2XmwTNN3yFQt4o+X4Li+ /wW2sRcZPyoMf5zp7mR0V2ps6ycQ55+fmMFMvbjpbR5l8I6nXPsGQTXlXYErrVYd5kDn A4mTxyw4J5yMZZP+wSpPoyd88NG7XXA76CjQGZjeklmKVYMUAzNeZEm/ZzLd9RdRBvWV he0XwNlfVVmOuNF+RNgao8+qMxMTIZ2LV+HrATwCMMDiTPOKjCrlkjd+zle/4RahsDZT y/oQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700756018; x=1701360818; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=vh2UKPMNx1L/5N+6LNgkvUvX17L29P0s2Gceuwy/h9o=; b=UKWyRPVRlYc1xMXRF6qrSAydqFC9M2guOHZ3pB6egBAGYnSofe00sLBR60RvaLpwOR brREh6SJhDDEIEhF53b6b2AdMU6FWgYdI1BlOI7WdUZ7BtbMYykw4W2QQw05e3fdUCjJ uPojPjyF3HDXzB6RojWP+d6EUvRT8WVkwd7qI6HUfHNEuEqrTR7DNnj0wtqlgot6p89u SOdS8Z0ThFjgserlUPjHe/ZUExpoR1B5h1mclBSXOF/FkH/7f+wv+k+A+sPzfob8lMbY xPc19MqQQBqcwpLzZw2JeRzp8BggdtKHwQAjSVg1KVulJK0spBp5LQewaJ459vjKkHlt kdNA== X-Gm-Message-State: AOJu0YyU5qMR1Ub6Agw+cIm1UJwpsT9ffunvH0M813bp2k2O68X+6F3n 3KIU0SfNMsJEF4uZtBAcXTIukrys8VcSULO/cg== X-Google-Smtp-Source: AGHT+IFyqadu9mdrWTeXdi81RAvUirFiB/pF8LSJFiPp5tctA1P5dgGkLOb4BkElbtAn1zzW9CDQTzKLRcnUW5jyZfk= X-Received: by 2002:a17:90b:1649:b0:281:20a0:dae3 with SMTP id il9-20020a17090b164900b0028120a0dae3mr5472828pjb.40.1700756017952; Thu, 23 Nov 2023 08:13:37 -0800 (PST) List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@freebsd.org MIME-Version: 1.0 References: <25943.60056.880614.452966@hergotha.csail.mit.edu> <91988E23-ED50-4379-AA5F-4B069E08D80F@karels.net> <7C7920E0-B0FC-4255-AD5C-ECBDDC18CF43@karels.net> In-Reply-To: <7C7920E0-B0FC-4255-AD5C-ECBDDC18CF43@karels.net> From: Rick Macklem Date: Thu, 23 Nov 2023 08:13:26 -0800 Message-ID: Subject: Re: NFS exports of ZFS snapshots broken To: Mike Karels Cc: FreeBSD CURRENT , Alexander Motin , Martin Matuska , Garrett Wollman Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spamd-Result: default: False [-4.00 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-0.998]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20230601]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36:c]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; MLMMJ_DEST(0.00)[freebsd-current@freebsd.org]; RCVD_COUNT_ONE(0.00)[1]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; FROM_EQ_ENVFROM(0.00)[]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; RCVD_IN_DNSWL_NONE(0.00)[2607:f8b0:4864:20::102d:from]; DKIM_TRACE(0.00)[gmail.com:+]; TAGGED_FROM(0.00)[]; FREEMAIL_FROM(0.00)[gmail.com]; FROM_HAS_DN(0.00)[]; MID_RHS_MATCH_FROMTLD(0.00)[]; RCVD_TLS_LAST(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; TO_DN_ALL(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com:dkim] X-Rspamd-Queue-Id: 4SbjpX0q0wz4VkV X-Spamd-Bar: --- On Sat, Nov 18, 2023 at 8:10=E2=80=AFPM Mike Karels wrote= : > > On 18 Nov 2023, at 21:19, Rick Macklem wrote: > > > On Sat, Nov 18, 2023 at 4:43=E2=80=AFPM Mike Karels w= rote: > >> > >> On 18 Nov 2023, at 17:23, Rick Macklem wrote: > >> > >>> On Sat, Nov 18, 2023 at 2:27=E2=80=AFPM Mike Karels = wrote: > >>>> > >>>> On 18 Nov 2023, at 15:58, Rick Macklem wrote: > >>>> > >>>>> On Sat, Nov 18, 2023 at 8:09=E2=80=AFAM Rick Macklem wrote: > >>>>>> > >>>>>> On Fri, Nov 17, 2023 at 8:19=E2=80=AFPM Mike Karels wrote: > >>>>>>> > >>>>>>> On 17 Nov 2023, at 22:14, Mike Karels wrote: > >>>>>>> > >>>>>>>> On 17 Nov 2023, at 21:24, Rick Macklem wrote: > >>>>>>>> > >>>>>>>>> Most of the changes in stable/13 that are not in releng/13.2 > >>>>>>>>> are the "make it work in a jail" stuff. Unfortunately, they are > >>>>>>>>> a large # of changes (mostly trivial edits adding vnet macros), > >>>>>>>>> but it also includes export check changes. > >>>>>>>>> > >>>>>>>>> I have attached a trivial patch that I think disables the expor= t > >>>>>>>>> checks for jails. If either of you can try it and see if it fix= es > >>>>>>>>> the problem, that would be great. > >>>>>>>>> (Note that this is only for testing, although it probably does = not > >>>>>>>>> matter unless you are running nfsd(8) in vnet jails.) > >>>>>>>> > >>>>>>>> Yes, I can see snapshots with the patch. This system is just a = test > >>>>>>>> system that doesn't normally run ZFS or NFS, so no problem messi= ng > >>>>>>>> with permissions. It's a bhyve VM, so I just added a small disk= and > >>>>>>>> enabled ZFS for testing. > >>>>>>> > >>>>>>> btw, you might try to get mm@ or maybe mav@ to help out from the = ZFS > >>>>>>> side. It must be doing something differently inside a snapshot t= han > >>>>>>> outside, maybe with file handles or something like that. > >>>>>> Yes. I've added freebsd-current@ (although Garrett is not on it, h= e is > >>>>>> cc'd) and these guys specifically... > >>>>>> > >>>>>> So, here's what appears to be the problem... > >>>>>> Commit 88175af (in main and stable/13, but not 13.2) added checks = for > >>>>>> nfsd(8) running in jails by filling in mnt_exjail with a reference= to the cred > >>>>>> used when the file system is exported. > >>>>>> When mnt_exjail is found NULL, the current nfsd code assumes that = there > >>>>>> is no access allowed for the mount. > >>>>>> > >>>>>> My vague understanding is that when a ZFS snapshot is accessed, it= is > >>>>>> "pseudo-mounted" by zfsctl_snapdir_lookup() and I am guessing that > >>>>>> mnt_exjail is NULL as a result. > >>>>>> Since I do not know the ZFS code and don't even have an easy way t= o > >>>>>> test this (thankfully Mike can test easily), I do not know what to= do from > >>>>>> here? > >>>>>> > >>>>>> Is there a "struct mount" constructed for this pseudo mount > >>>>>> (or it actually appears to be the lookup of ".." that fails, so it > >>>>>> might be the parent of the snapshot subdir?)? > >>>>>> > >>>>>> One thought is that I can check to see if the mount pointer is in = the > >>>>>> mountlist (I don't think the snapshot's mount is in the mountlist)= and > >>>>>> avoid the jail test for this case. This would assume that snapsho= ts are > >>>>>> always within the file system(s) exported via that jail (which inc= ludes > >>>>>> the case of prison0, of course), so that they do not need a separa= te > >>>>>> jail check. > >>>>>> > >>>>>> If this doesn't work, there will need to be some sort of messing a= bout > >>>>>> in ZFS to set mnt_exjail for these. > >>>>> Ok, so now onto the hard part... > >>>>> Thanks to Mike and others, I did create a snapshot under .zfs and I= can > >>>>> see the problem. It is that mnt_exjail =3D=3D NULL. > >>>>> Now, is there a way that this "struct mount" can be recognized as "= special" > >>>>> for snapshots, so I can avoid the mnt_exjail =3D=3D NULL test? > >>>>> (I had hoped that "mp->mnt_list.tqe_prev" would be NULL, but that i= s not > >>>>> the case.) > >>>> > >>>> Dumb question, is the mount point (mp presumably) different between = the > >>>> snapshot and the main file system? > >>> Not a dump question and the answer is rather interesting... > >>> It is "sometimes" or "usually" according to my printf(). > >>> It seems that when you first "cd >>> where mnt_exjail =3D=3D NULL.. Then when you look at directories with= in the > >>> snapshot, you get the mp of the file system that .zfs exists in, whic= h does > >>> have mnt_exjail set non-NULL. > >>> > >>> There is this snippet of code in zfsctl_snapdir_lookup(): > >>> /* > >>> * Fix up the root vnode mounted on .zfs/snapshot/. > >>> * > >>> * This is where we lie about our v_vfsp in order to > >>> * make .zfs/snapshot/ accessible over NFS > >>> * without requiring manual mounts of . > >>> */ > >>> ASSERT3P(VTOZ(*vpp)->z_zfsvfs, !=3D, zfsvfs); > >>> VTOZ(*vpp)->z_zfsvfs->z_parent =3D zfsvfs; > >>> > >>> /* Clear the root flag (set via VFS_ROOT) as well. */ > >>> (*vpp)->v_vflag &=3D ~VV_ROOT; > >>> which seems to set the mp to that of the parent, but it > >>> seems this does not happen for the initial lookup of > >>> the ? > >>> > >>> I'll note that there is code before this in > >>> zfsctl_snapdir_lookup() for handling cases > >>> like "." and ".." that return without doing this. > >>> > >>> Now, why does this work without the mnt_exjail > >>> check (as in 13.2)? > >>> I am not quite sure, but there is this "cheat" in the > >>> NFS server (it has been there for years, maybe decades): > >>> /* > >>> * Allow a Lookup, Getattr, GetFH, Secinfo on an > >>> * non-exported directory if > >>> * nfs_rootfhset. Do I need to allow any other Ops? > >>> * (You can only have a non-exported vpnes if > >>> * nfs_rootfhset is true. See nfsd_fhtovp()) > >>> * Allow AUTH_SYS to be used for file systems > >>> * exported GSS only for certain Ops, to allow > >>> * clients to do mounts more easily. > >>> */ > >>> if (nfsv4_opflag[op].needscfh && vp) { > >>> if (!NFSVNO_EXPORTED(&vpnes) && > >>> op !=3D NFSV4OP_LOOKUP && > >>> op !=3D NFSV4OP_GETATTR && > >>> op !=3D NFSV4OP_GETFH && > >>> op !=3D NFSV4OP_ACCESS && > >>> op !=3D NFSV4OP_READLINK && > >>> op !=3D NFSV4OP_SECINFO && > >>> op !=3D NFSV4OP_SECINFONONAME) > >>> nd->nd_repstat =3D NFSERR_NOFILEHANDLE; > >>> This allows certain operations to be done on > >>> non-exported file systems and I think that is enough > >>> to allow this to work when mnt_exjail is not checked. > >>> (Note that NFSV4OP_LOOKUPP is not in the list, > >>> which might explain why it is the one that fails for > >>> Garrett. I don't think it can be added to this list > >>> safely, since that would allow a client to move above > >>> the exported file system into "uncharted territory".) > >>> > >>>> Just curious. Also, what is mnt_exjail > >>>> normally set to for file systems not in a jail? > >>> mnt_exjail is set to the credentials of the thread/process > >>> that exported the file system (usually mountd(8)). > >>> When not in a jail, cr_prison for these credentials > >>> points to prison0. > >>> > >>> Btw, I checked and the "other mp that has mnt_exjail =3D=3D NULL > >>> is in the mountlist, so the idea of checking "not in mountlist" > >>> is a dead end. > >>> > >>> I am looking for something "unique" about this other mp, > >>> but haven't found anything yet. > >>> Alternately, it might be necessary to add code to > >>> zfsctl_snapdir_lookup() to "cheat and change the mp" > >>> in more cases, such as "." and ".." lookups? > >> > >> It seems to me that if ZFS is creating an additional mount structure, > >> it should be responsible for setting it up correctly. That could > >> involve a vfs-level routine to do some of the cloning. In any case, > >> it seems to me that mnt_exjail should be set properly, e.g. by duping > >> the one in the original mount structure. Probably ZFS is the only > >> file system type that would need this added. > > I've created a patch that I think does this. It seemed to test ok for m= y case. > > It's in D42672 on reviews.freebsd.org. > > I have also attached it here (this diff doesn't use -U999999, so it mig= ht be > > easier to apply). > > It works for me in 13-stable, and looks plausible. The patch has now been fixed so that there is no race between vfs_exjail_cl= one() and a jail dying. I believe the current patch fixes the problem. The patch can be found as an attachment to PR#275200 (that is a FreeBSD bug= zilla problem report, not an OpenZFS pull request). I will not close the PR until the above has all happened. This patch will be needed for systems running stable/13, stable/14 and 14.0= . The vfs_exjail_clone() part of the patch is now committed to main and will = be MFC'd in 3 days. The ZFS part of the patch is a pull request on OpenZFS. I cannot say how long the ZFS part takes or if/when an errata to 14.0 will happen. Sorry about the breakage and thanks for reporting it (and persevering when I said I knew nothing about ZFS, which is true). Thanks goes to Mike Karels= , who was able to determine that the problem was not in 13.2, but was in stable/13, which allowed me to conclude it was a "nfsd in jail" related breakage. rick > > Mike > > > Hopefully this fixes the problem. Sorry for the breakage. > > > > rick > > > >> > >> Mike > >> > >>> rick > >>> ps: I added all the cc's back in because I want the > >>> ZFS folk to hopefully chime in. > >>> > >>>> > >>>> Mike > >>>> > >>>>> Do I need to search mountlist for it? > >>>>> > >>>>> rick > >>>>> ps: The hack patch attached should fix the problem, but can only be > >>>>> safely used if mountd/nfsd are not run in any jails. > >>>>> > >>>>>> > >>>>>> I will try and get a test setup going here, which leads me to.. > >>>>>> how do I create a ZFS snapshot? (I do have a simple ZFS pool runni= ng > >>>>>> on a test machine, but I've never done a snapshot.) > >>>>>> > >>>>>> Although this problem is not in 13.2, it will have shipped in 14.0= . > >>>>>> > >>>>>> Any help with be appreciated, rick > >>>>>> > >>>>>>> > >>>>>>> Mike > >>>>>>>> > >>>>>>>>> rick > >>>>>>>>> > >>>>>>>>> On Fri, Nov 17, 2023 at 6:14=E2=80=AFPM Mike Karels wrote: > >>>>>>>>>> > >>>>>>>>>> CAUTION: This email originated from outside of the University = of Guelph. Do not click links or open attachments unless you recognize the = sender and know the content is safe. If in doubt, forward suspicious emails= to IThelp@uoguelph.ca. > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> Rick, have you been following this thread on freebsd-stable? = I have been able > >>>>>>>>>> to reproduce this using a 13-stable server from Oct 7 and a 15= -current system > >>>>>>>>>> that is up to date using NFSv3. I did not reproduce with a 13= .2 server. The > >>>>>>>>>> client was running 13.2. Any ideas? A full bisect seems fair= ly painful, but > >>>>>>>>>> maybe you have an idea of points to try. Fortunately, these a= re all test > >>>>>>>>>> systems that I can reboot at will. > >>>>>>>>>> > >>>>>>>>>> Mike > >>>>>>>>>> > >>>>>>>>>> Forwarded message: > >>>>>>>>>> > >>>>>>>>>>> From: Garrett Wollman > >>>>>>>>>>> To: Mike Karels > >>>>>>>>>>> Cc: freebsd-stable@freebsd.org > >>>>>>>>>>> Subject: Re: NFS exports of ZFS snapshots broken > >>>>>>>>>>> Date: Fri, 17 Nov 2023 17:35:04 -0500 > >>>>>>>>>>> > >>>>>>>>>>> < said: > >>>>>>>>>>> > >>>>>>>>>>>> I have not run into this, so I tried it just now. I had no = problem. > >>>>>>>>>>>> The server is 13.2, fully patched, the client is up-to-date = -current, > >>>>>>>>>>>> and the mount is v4. > >>>>>>>>>>> > >>>>>>>>>>> On my 13.2 client and 13-stable server, I see: > >>>>>>>>>>> > >>>>>>>>>>> 25034 ls CALL open(0x237d32f9a000,0x120004) > >>>>>>>>>>> 25034 ls NAMI "/mnt/tools/.zfs/snapshot/weekly-2023-4= 5" > >>>>>>>>>>> 25034 ls RET open 4 > >>>>>>>>>>> 25034 ls CALL fcntl(0x4,F_ISUNIONSTACK,0x0) > >>>>>>>>>>> 25034 ls RET fcntl 0 > >>>>>>>>>>> 25034 ls CALL getdirentries(0x4,0x237d32faa000,0x1000= ,0x237d32fa7028) > >>>>>>>>>>> 25034 ls RET getdirentries -1 errno 5 Input/output e= rror > >>>>>>>>>>> 25034 ls CALL close(0x4) > >>>>>>>>>>> 25034 ls RET close 0 > >>>>>>>>>>> 25034 ls CALL exit(0) > >>>>>>>>>>> > >>>>>>>>>>> Certainly a libc bug here that getdirentries(2) returning [EI= O] > >>>>>>>>>>> results in ls(1) returning EXIT_SUCCESS, but the [EIO] error = is > >>>>>>>>>>> consistent across both FreeBSD and Linux clients. > >>>>>>>>>>> > >>>>>>>>>>> Looking at this from the RPC side: > >>>>>>>>>>> > >>>>>>>>>>> (PUTFH, GETATTR, LOOKUP(snapshotname), GETFH, GETATTR) > >>>>>>>>>>> [NFS4_OK for all ops] > >>>>>>>>>>> (PUTFH, GETATTR) > >>>>>>>>>>> [NFS4_OK, NFS4_OK] > >>>>>>>>>>> (PUTFH, ACCESS(0x3f), GETATTR) > >>>>>>>>>>> [NFS4_OK, NFS4_OK, rights =3D 0x03, NFS4_OK] > >>>>>>>>>>> (PUTFH, GETATTR, LOOKUPP, GETFH, GETATTR) > >>>>>>>>>>> [NFS4_OK, NFS4_OK, NFS4ERR_NOFILEHANDLE] > >>>>>>>>>>> > >>>>>>>>>>> and at this point the [EIO] is returned. > >>>>>>>>>>> > >>>>>>>>>>> It seems that clients always do a LOOKUPP before calling READ= DIR, and > >>>>>>>>>>> this is failing when the subject file handle is the snapshot.= The > >>>>>>>>>>> client is perfectly able to *traverse into* the snapshot: if = I try to > >>>>>>>>>>> list a subdirectory I know exists in the snapshot, the client= is able to > >>>>>>>>>>> LOOKUP(dirname) just fine, but LOOKUPP still fails with > >>>>>>>>>>> NFS4ERR_NOFILEHANDLE *on the subndirectory*. > >>>>>>>>>>> > >>>>>>>>>>> -GAWollman > >>>>>>>>>>