From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-21.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 84E88C4338F for ; Sat, 21 Aug 2021 12:09:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C59B61216 for ; Sat, 21 Aug 2021 12:09:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232045AbhHUMKJ (ORCPT ); Sat, 21 Aug 2021 08:10:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:46186 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229968AbhHUMKJ (ORCPT ); Sat, 21 Aug 2021 08:10:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 28E7C6121E for ; Sat, 21 Aug 2021 12:09:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629547770; bh=dvKju+y+05RZe6v3yn+dSI4/25QRU490ORmOPSmsOjE=; h=In-Reply-To:References:From:Date:Subject:To:Cc:From; b=gI8wJaCBNYk1UMS5Mf0DU7iQQmGeDD9/W8Rob4bw21f6RI5JAOPBlFZ1QuXz0Cbm0 bRdW9hmWDENba4pjqIY9bUwenErRlsTYDmurTg7IUJS0vis2hLr/mGxKb/dV9wGRg3 wwQirF973sVwE9GmnZqGw3YCDgZWQzBtbU9Bb/u/Hg8iCAWhPKnWItOwZCS3HtOUzA UeWSiHSy3JsKxgAoCxyBpFcgBitzbUSYeTNsmcc9uSaU4BRwP4VjW3I2DNHyvn5qJg uu7au91pqhaCQfQrmMONoxGRYjpsqFtsxkI1gLvnwXag4WA8VcMq6gSh0uqjDb2+Hj MBhrtH5lj7HGw== Received: by mail-ot1-f49.google.com with SMTP id x10-20020a056830408a00b004f26cead745so21354414ott.10 for ; Sat, 21 Aug 2021 05:09:30 -0700 (PDT) X-Gm-Message-State: AOAM530vQy1Tru9a00+Y6fzDPBe/iKN3sEtAWQyQ2kU0eniTTrgZWPWA j0/u+pP01R7hCLFdJAGf6SmlOVK4ZLuNhNm5PBc= X-Google-Smtp-Source: ABdhPJzxWRu8kZ3mFDz8qWZEWc3h2kJv8CFrqY16ygH9NmMQPk8hHINIEM15wRMzRVyudCVF6Y8jAgtlrTinqeSzcrU= X-Received: by 2002:a05:6830:25ce:: with SMTP id d14mr20879229otu.87.1629547769473; Sat, 21 Aug 2021 05:09:29 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:ac9:1bc6:0:0:0:0:0 with HTTP; Sat, 21 Aug 2021 05:09:28 -0700 (PDT) In-Reply-To: <20210821113948.nxzdktqnw36vsyhb@wittgenstein> References: <20210816115605.178441-1-brauner@kernel.org> <008d01d792f6$c2735f30$475a1d90$@samsung.com> <20210818174539.ro2ryrbku3ozdjvi@wittgenstein> <000001d794a0$94ec20a0$bec461e0$@samsung.com> <20210819130136.zziq7yr4htiowb5n@wittgenstein> <20210821111117.ngkyc5n6vplayrhx@wittgenstein> <20210821113948.nxzdktqnw36vsyhb@wittgenstein> From: Namjae Jeon Date: Sat, 21 Aug 2021 21:09:28 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] ksmbd: fix lookup on idmapped mounts To: Christian Brauner Cc: Namjae Jeon , Steve French , Christian Brauner , Sergey Senozhatsky , David Sterba , Christoph Hellwig , Hyunchul Lee , linux-cifs@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org 2021-08-21 20:39 GMT+09:00, Christian Brauner : > On Sat, Aug 21, 2021 at 01:11:17PM +0200, Christian Brauner wrote: >> On Sat, Aug 21, 2021 at 02:59:21PM +0900, Namjae Jeon wrote: >> > 2021-08-19 22:01 GMT+09:00, Christian Brauner >> > : >> > > On Thu, Aug 19, 2021 at 11:19:04AM +0900, Namjae Jeon wrote: >> > >> > On Tue, Aug 17, 2021 at 08:30:55AM +0900, Namjae Jeon wrote: >> > >> > > > From: Christian Brauner >> > >> > > > >> > >> > > > It's great that the new in-kernel ksmbd server will support >> > >> > > > idmapped >> > >> > > > mounts out of the box! However, lookup is currently broken. >> > >> > > > Lookup >> > >> > > > helpers such as lookup_one_len() call inode_permission() >> > >> > > > internally >> > >> > > > to ensure that the caller is privileged over the inode of the >> > >> > > > base >> > >> > > > dentry they are trying to >> > >> > lookup under. So the permission checking here is currently wrong. >> > >> > > > >> > >> > > > Linux v5.15 will gain a new lookup helper lookup_one() that >> > >> > > > does >> > >> > > > take idmappings into account. I've added it as part of my >> > >> > > > patch >> > >> > > > series to make btrfs support idmapped mounts. The new helper is >> > >> > > > in >> > >> > > > linux- next as part of David's (Sterba) btrfs for-next branch >> > >> > > > as >> > >> > > > commit c972214c133b ("namei: add >> > >> > mapping aware lookup helper"). >> > >> > > > >> > >> > > > I've said it before during one of my first reviews: I would >> > >> > > > very >> > >> > > > much recommend adding fstests to >> > >> > [1]. >> > >> > > > It already seems to have very rudimentary cifs support. There >> > >> > > > is a >> > >> > > > completely generic idmapped mount testsuite that supports >> > >> > > > idmapped >> > >> > > > mounts. >> > >> > > > >> > >> > > > [1]: https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git/ >> > >> > > > Cc: Steve French >> > >> > > > Cc: Christoph Hellwig >> > >> > > > Cc: Namjae Jeon >> > >> > > > Cc: Hyunchul Lee >> > >> > > > Cc: Sergey Senozhatsky >> > >> > > > Cc: David Sterba >> > >> > > > Cc: linux-cifs@vger.kernel.org >> > >> > > > Signed-off-by: Christian Brauner >> > >> > > > >> > >> > > > --- >> > >> > > Hi Christian, >> > >> > > >> > >> > > > I merged David's for-next tree into cifsd-next to test this. I >> > >> > > > did >> > >> > > > only compile test this. If someone gives me a clear set of >> > >> > > > instructions how to test ksmbd on my local machine I can at >> > >> > > > least >> > >> > > > try to cut some time out of my week to do more reviews. (I'd >> > >> > > > especially like to see acl behavior with ksmbd.) >> > >> > > >> > >> > > There is "How to run ksmbd" section in patch cover letter. >> > >> > > >> > >> > > https://protect2.fireeye.com/v1/url?k=65ecaaf0-3a779239-65ed21bf-0cc47 >> > >> > > a336fae-53bc47005a1a97a9&q=1&e=e44c9f9f-d7ae-4768-8cc2-8f02d748fc6e&u= >> > >> > > https%3A%2F%2Flkml.org%2Flkml%2F2021%2F8%2F5%2F54 >> > >> > > >> > >> > > Let me know if it doesn't work well even if you try to run it >> > >> > > with >> > >> > > this step. >> > >> > > And We will also check whether your patch work fine. >> > >> > > >> > >> > > > >> > >> > > > One more thing, the tree for ksmbd was very hard to find. I had >> > >> > > > to >> > >> > > > do a lot archeology to end up >> > >> > at: >> > >> > > > >> > >> > > > git://git.samba.org/ksmbd.git >> > >> > > This is also in the patch cover letter. See "Mailing list and >> > >> > > repositories" section. >> > >> > > I think that you can use : >> > >> > > >> > >> > > https://protect2.fireeye.com/v1/url?k=8af83a5d-d5630294-8af9b112-0cc47 >> > >> > > a336fae-e471ffbdb93d05b7&q=1&e=e44c9f9f-d7ae-4768-8cc2-8f02d748fc6e&u= >> > >> > > https%3A%2F%2Fgithub.com%2Fnamjaejeon%2Fsmb3-kernel%2Ftree%2Fksmbd-v7- >> > >> > > series >> > >> > > >> > >> > > > >> > >> > > > Would be appreciated if this tree could be reflected in >> > >> > > > MAINTAINERS >> > >> > > > or somewhere else. The github repos with the broken out >> > >> > > > patches/module aren't really that helpful. >> > >> > > Okay, I will add git address of ksmbd in MAINTAINERS on next >> > >> > > spin. >> > >> > > >> > >> > > > >> > >> > > > Thanks! >> > >> > > > Christian >> > >> > > Really thanks for your review and I will apply this patch after >> > >> > > checking it. >> > >> > >> > >> > Thank your for the pointers. >> > >> > >> > >> > Ok, so I've been taking the time to look into cifs and ksmbd today. >> > >> > My >> > >> > mental model was wrong. There >> > >> > are two things to consider here: >> > >> > >> > >> > 1. server: idmapped mounts with ksmbd >> > >> > 2. client: idmapped mounts with cifs >> > >> > >> > >> > Your patchset adds support for 1. >> > >> Right. >> > >> >> > >> > Let's say I have the following ksmbd config: >> > >> > >> > >> > root@f2-vm:~# cat /etc/ksmbd/smb.conf >> > >> > [global] >> > >> > netbios name = SMBD >> > >> > server max protocol = SMB3 >> > >> > [test] >> > >> > path = /opt >> > >> > writeable = yes >> > >> > comment = TEST >> > >> > read only = no >> > >> > >> > >> > So /opt can be an idmapped mount and ksmb would know how to deal >> > >> > with >> > >> > that correctly, i.e. you could >> > >> > do: >> > >> > >> > >> > mount-idmapped --map-mount=b:1000:0:1 /opt /opt >> > >> > >> > >> > ksmbd.mountd >> > >> > >> > >> > and ksmbd would take the idmapping of /opt into account. >> > >> Right. >> > >> >> > >> > >> > >> > That however is different from 2. which is cifs itself being >> > >> > idmappable. >> > >> Right. >> > >> >> > >> > Whether or not that makes sense or is needed will need some >> > >> > thinking. >> > >> > >> > >> > In any case, this has consequences for xfstests and now I >> > >> > understand >> > >> > your earlier confusion. In >> > >> > another mail you pointed out that cifs reports that idmapped mounts >> > >> > are >> > >> > not supported. That is correct >> > >> > insofar as it means 2. is not supported, i.e. you can't do: >> > >> Right. >> > >> >> > >> > >> > >> > mount -t cifs -o username=foo,password=bar //server/files /mnt >> > >> > >> > >> > and then >> > >> > >> > >> > mount-idmapped --map-mount=b:1000:0:1 /mnt /mnt >> > >> > >> > >> > but that's also not what you want in order to test for ksmbd. What >> > >> > you >> > >> > want is to test 1. >> > >> Right. So we have manually tested it, not xfstests. >> > >> >> > >> > >> > >> > So your test setup would require you to setup an idmapped mount and >> > >> > have >> > >> > ksmbd use that which can then >> > >> > be mounted by a client. >> > >> > >> > >> > With your instructions I was at least able to get a ksmb instance >> > >> > running and be able to mount a >> > >> > client with -t cifs. All on the same machine, i.e. my server is >> > >> > localhost. >> > >> Okay. >> > >> >> > >> > >> > >> > However, I need to dig a bit into the semantics to make better >> > >> > assertions about what's going on. >> > >> Okay. And I have applied your patch to ksmbd. >> > >> >> > >> > >> > >> > Are unix extension supported with ksmb? Everytime I try to use >> > >> > "posix" >> > >> > as a mount option with mount -t cifs -o //127.0.0.1/test /mnt I >> > >> > get >> > >> > "uid=0" and "gid=0" and "noposix". >> > >> > I do set "unix extensions = yes" in both the samba and ksmbd >> > >> > smb.conf. >> > >> With posix mount option, It should work. It worked well before but it >> > >> is >> > >> strange now. >> > >> >> > >> I'm not sure this is the correct fix, But could you please try to >> > >> mount >> > >> with the below change ? >> > >> >> > >> diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c >> > >> index eed59bc1d913..5fd0b0ddcc57 100644 >> > >> --- a/fs/cifs/fs_context.c >> > >> +++ b/fs/cifs/fs_context.c >> > >> @@ -1268,8 +1268,10 @@ static int smb3_fs_context_parse_param(struct >> > >> fs_context *fc, >> > >> case Opt_unix: >> > >> if (result.negated) >> > >> ctx->linux_ext = 0; >> > >> - else >> > >> + else { >> > >> + ctx->linux_ext = 1; >> > >> ctx->no_linux_ext = 1; >> > >> + } >> > >> break; >> > >> case Opt_nocase: >> > >> ctx->nocase = 1; >> > > >> > > That stops the bleeding indeed. :) >> > Okay, sorry for late response. >> > > I think a slightly nicer fix might be: >> > > >> > > diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c >> > > index eed59bc1d913..424b8dc2232e 100644 >> > > --- a/fs/cifs/fs_context.c >> > > +++ b/fs/cifs/fs_context.c >> > > @@ -1269,7 +1269,8 @@ static int smb3_fs_context_parse_param(struct >> > > fs_context *fc, >> > > if (result.negated) >> > > ctx->linux_ext = 0; >> > > else >> > > - ctx->no_linux_ext = 1; >> > > + ctx->linux_ext = 1; >> > > + ctx->no_linux_ext = !ctx->linux_ext; >> > > break; >> > > case Opt_nocase: >> > > ctx->nocase = 1; >> > > >> > > So with this patch applied I got unix permissions working after all. >> > > So >> > > I was able to do some more testing. >> > Okay. >> > > >> > > Just a few questions (independent of idmapped mounts): >> > > >> > > 1. Are the "uid=" and "gid=" mount options ignored when "username=" >> > > is >> > > specified and "posix" is specified? >> > > >> > > It seems that "uid=" and "gid=" have are silently ignored when >> > > "posix' is set. They are neither used to report file ownership >> > > under >> > > the cifs mountpoint nor are they relevant when determining >> > > ownership >> > > on disk? >> > > >> > > As an example, assume I have added a user "foo" with uid 1000 to >> > > ksmbd via: >> > > >> > > ksmbd.adduser -a foo >> > > >> > > And I mounted a share via: >> > > >> > > mount -t cifs -o >> > > username=foo,password=bar,posix,uid=1234,gid=1234,forceuid,forcegid >> > > //127.0.0.1/test /mnt >> > > >> > > i) Ownership in /mnt appears posix-correct, i.e. "uid=" and "gid=" >> > > have >> > > no effect on the reported ownership. >> > > >> > > ii) Assume I'm logged in as the root user with uid 0. If I create >> > > file or directory in /mnt it will be owned by user foo, i.e. >> > > uid >> > > 1000, i.e., the "uid=1234" and "gid=1234" mount option have >> > > zero >> > > effect on the ownership of the files? >> > > >> > > 2. Are the "uid=" and "gid=" options ignored for permission checking >> > > when "posix" is specified? >> > > >> > > 3. Am I correct in assuming that there is no mount option that makes >> > > chown() or chmod() have an actual effect. >> > That will be an answer for 1,2, 3 question. There are mount options for >> > this. >> > 1. modefromsid >> > 2. idsfromsid >> > >> > You can use this mount option and please check it. >> >> Thank you! This works and finally I can hit some codepaths I wasn't able >> to until now. >> >> > > >> > > cifs seems to have support for it but the ksmbd server doesn't >> > > seem >> > > to? >> > No, you need to use mount options for this as I said. >> > ksmbd have supported it but I found an issue related to chown and have >> > fixed. >> > >> > Could you please check the below git branch (pulled David'tree + ksmbd >> > fixes) ? >> > >> > git clone --branch=for-christian >> > https://github.com/namjaejeon/smb3-kernel >> >> Thanks, I've pulled that branch. > > There's two problems in this patch. I'll post and point out here > quickly, if you don't mind: Thanks for your reiview! > > commit fd7d13c387798cbc3abd68ecc07b2c868c6d96cb > Author: Namjae Jeon > Date: Sat Aug 21 14:39:43 2021 +0900 > > ksmbd: fix permission check issue on chown and chmod > > When commanding chmod and chown on cifs&ksmbd, ksmbd allows it without > file > permissions check. There is code to check it in settattr_prepare. > Instead of setting the inode directly, update the mode and uid/gid > through notify_change. > > Signed-off-by: Namjae Jeon > Signed-off-by: Steve French > > diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c > index 0131997c2177..d329ea49fa14 100644 > --- a/fs/ksmbd/smb2pdu.c > +++ b/fs/ksmbd/smb2pdu.c > @@ -5861,10 +5861,15 @@ int smb2_set_info(struct ksmbd_work *work) > break; > case SMB2_O_INFO_SECURITY: > ksmbd_debug(SMB, "GOT SMB2_O_INFO_SECURITY\n"); > + if (ksmbd_override_fsids(work)) { > + rc = -ENOMEM; > + goto err_out; > + } > rc = smb2_set_info_sec(fp, > > le32_to_cpu(req->AdditionalInformation), > req->Buffer, > le32_to_cpu(req->BufferLength)); > + ksmbd_revert_fsids(work); > break; > default: > rc = -EOPNOTSUPP; > diff --git a/fs/ksmbd/smbacl.c b/fs/ksmbd/smbacl.c > index 20455d810523..f28af33c0bd5 100644 > --- a/fs/ksmbd/smbacl.c > +++ b/fs/ksmbd/smbacl.c > @@ -1300,6 +1300,7 @@ int set_info_sec(struct ksmbd_conn *conn, struct > ksmbd_tree_connect *tcon, > struct smb_fattr fattr = {{0}}; > struct inode *inode = d_inode(path->dentry); > struct user_namespace *user_ns = mnt_user_ns(path->mnt); > + struct iattr newattrs; > > fattr.cf_uid = INVALID_UID; > fattr.cf_gid = INVALID_GID; > @@ -1309,12 +1310,28 @@ int set_info_sec(struct ksmbd_conn *conn, struct > ksmbd_tree_connect *tcon, > if (rc) > goto out; > > - inode->i_mode = (inode->i_mode & ~0777) | (fattr.cf_mode & 0777); > - if (!uid_eq(fattr.cf_uid, INVALID_UID)) > - inode->i_uid = fattr.cf_uid; > - if (!gid_eq(fattr.cf_gid, INVALID_GID)) > + newattrs.ia_valid = ATTR_CTIME; > + if (!uid_eq(fattr.cf_uid, INVALID_UID)) { > + newattrs.ia_valid |= ATTR_UID; > + newattrs.ia_uid = fattr.cf_uid; > + } > + if (!gid_eq(fattr.cf_gid, INVALID_GID)) { > inode->i_gid = fattr.cf_gid; > > This needs to be removed. If setattr_prepare() fails you will still end > up with inode->i_gid changed, i.e. you're changing group ownership even > if you fail the subsequent setattr_prepare(). Oops, My mistake, I am missing remove this line. > > - mark_inode_dirty(inode); > + newattrs.ia_valid |= ATTR_GID; > + newattrs.ia_gid = fattr.cf_gid; > + } > + newattrs.ia_valid |= ATTR_MODE; > + newattrs.ia_mode = (inode->i_mode & ~0777) | (fattr.cf_mode & > 0777); > + rc = setattr_prepare(user_ns, path->dentry, &newattrs); > + if (rc) > + goto out; > + > + inode_lock(inode); > + setattr_copy(user_ns, inode, &newattrs); > > This needs to be removed. setattr_copy() will be called in the > i_io->setattr() > method of the underlying filesystem which notify_change() will all. > > Right now, with the setattr_copy() will commit the changes to the inode. > If the following notify_change() call fails you end up with a change in > ownership that should've failed. Okay, I will remove it. Thanks! > > Christian >