From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9210828373 for ; Mon, 26 May 2025 14:55:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748271335; cv=none; b=rrUhHmp2gvj74UqNdxweDJer+0JRFrZRpetEuVhH8ShlA6bDfDxmzDMfilHIm8mEMFPEr3o/N2Uu4SnLwCVRFm03B4h+nrwQHRMhzeUQaWCvQf6sqPgv3AIkvceIC+aHaVwQn6FXNGPr+jI+J/3t8OwpNaf5SI/UmWuRElCsQoo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748271335; c=relaxed/simple; bh=sBUbIJSlMS6QyIj/JhMZL5DC9wjpx0QvOu0usd6p70o=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=WXceLoCexIe+4My78PMyXptInqGlDxRb9MEpZrzTFUl2M2FetZwrFpHn6nbbY1FDn8Lq7gzJmFSD+ZZYQ1v/AAKkrkVQKLB+BOXOBa1UWwRz+cZy/P4ydT8JBCTdvyZJb/U6MoDwmZOdotuidmv+frcuQbK4ydk4miR0zMS2bYU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YCUBzLTa; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YCUBzLTa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9EA86C4CEE7; Mon, 26 May 2025 14:55:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1748271335; bh=sBUbIJSlMS6QyIj/JhMZL5DC9wjpx0QvOu0usd6p70o=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=YCUBzLTaUtkQirbawAEPK22h7cJGoPoHtL1NY8cdOcs9JIWPYYkE/lXcBPx6xYYk8 NO6yjiSpJjqlrO/iqk8I/rgAEWHaFnlGEScfhutElCsabDJ/BUW0LQdPYlwGb4ecVF UJjyTw1HJl9kFMcBzdZwTVCzkbZgZe59iOkb71+Y54MoOO2P7ke1hL0TDkewZRYAC/ VLTFCa6cMIDOAUQMmE05ttI7xa97xHeAFi0VtRRPLeCLisURA30vv5DjyyZtJQbdw7 MOstzAibdUzyKj5TFGdrYUaLURRG6My7GSLhiJVUByR5T4Yz0Wn8PYDqhfjA2lWIoG dPQDLTYNQjFwg== Message-ID: <745554aad3cce0a1c463ff0fc0e80028ba61803d.camel@kernel.org> Subject: Re: Questions Regarding Delegation Claim Behavior From: Jeff Layton To: Petro Pavlov , Chuck Lever Cc: Roi Azarzar , linux-nfs@vger.kernel.org Date: Mon, 26 May 2025 10:55:33 -0400 In-Reply-To: References: <2529724b-ad96-4b02-9d8e-647ef21eab03@oracle.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV 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version =E2=80=94 the correct version is 6.15.0-rc3+ (I believe it= 's from the branch you gave us). Regarding the client, I'm using hand-writt= en tests based on pynfs. > I believe the following section of the RFC may be relevant to the use of = a delegation stateid in relation to the file being accessed: > > If the stateid type is not valid for the context in which the stateid a= ppears, return NFS4ERR_BAD_STATEID. Note that a stateid may be valid in gen= eral, as would be reported by the TEST_STATEID operation, but be invalid fo= r a particular operation, as, for example, when a stateid that doesn't repr= esent byte-range locks is passed to the non-from_open case of LOCK or to LO= CKU, or when a stateid that does not represent an open is passed to CLOSE o= r OPEN_DOWNGRADE. In such cases, the server MUST return NFS4ERR_BAD_STATEID= . >=20 > I did some further investigation and identified another scenario that see= ms problematic: > =C2=A0=C2=A0=C2=A01.=20 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0Client1 creates file1 without a deleg= ation, with read-write access. It writes some data, changes the file mode t= o 444, and then closes the file. > =C2=A0=C2=A0=C2=A02.=20 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0Client2 opens file1 with read access,= receives a read delegation (deleg1), and closes the file without returning= the delegation. > =C2=A0=C2=A0=C2=A03.=20 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0Client2 then creates file2 with read-= write access, receives a write delegation (deleg2), and leaves the file ope= n (delegation is not returned). > =C2=A0=C2=A0=C2=A04.=20 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0Client2 tries to open file1 with writ= e access and receives an ACCESS_DENIED error (expected). > =C2=A0=C2=A0=C2=A05. Next, Client2 attempts to open=C2=A0file1=C2=A0 with= write access using CLAIM_DELEGATE_CUR, providing the stateid from=C2=A0del= eg2=C2=A0 (which was issued for=C2=A0file2) =E2=80=94 unexpectedly, the ope= ration succeeds. > =C2=A0=C2=A0=C2=A06.=20 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0Client2 proceeds to write to file1, a= nd it also succeeds =E2=80=94 despite the file being set to 444, where no w= rite access should be allowed. > This behavior seems incorrect, as I would expect the write operation to f= ail due to file permissions. > Please see the attached PCAP file for reference. > Best regards, > Petro Pavlov >=20 Yeah, that does seem like a bug. Mostly, the server treats CLAIM_DELEGATE_CUR and CLAIM_NULL identically. We have this in do_open_lookup() though: if (open->op_created || = =20 open->op_claim_type =3D=3D NFS4_OPEN_CLAIM_DELEGATE= _CUR) =20 accmode |=3D NFSD_MAY_OWNER_OVERRIDE; = =20 status =3D do_open_permission(rqstp, *resfh, open, accmode); = =20 set_change_info(&open->op_cinfo, current_fh); = =20 ...and that effectively bypasses the permission check in this case. Maybe we should add a fh check there? I'm not sure why CLAIM_DELEGATE_CUR wasn't deprecated when CLAIM_DELEGATE_CUR_FH was added to the spec. Is there some use case where CUR is necessary instead of CUR_FH? > On Fri, May 23, 2025 at 5:41=E2=80=AFPM Chuck Lever wrote: > > On 5/22/25 11:51 AM, Petro Pavlov wrote: > > > Hello, > > >=20 > > > My name is Petro Pavlov, I'm a developer at VAST. > > >=20 > > > I have a few questions about the delegation claim behavior observed i= n > > > the Linux kernel version 3.10.0-1160.118.1.el7.x86_64. > > >=20 > > > I=E2=80=99ve written the following test case: > > >=20 > > > =C2=A0 1. Client1 opens *file1* with a write delegation; the server g= rants > > > =C2=A0 =C2=A0 =C2=A0both the open and delegation (*delegation1*). > >=20 > > Since you mention a write delegation, I'll assume you are using Linux > > as an NFS client, and the server is not Linux, since that kernel versio= n > > does not implement server-side write delegation. > >=20 > >=20 > > > =C2=A0 2. Client1 closes the open but does not return the delegation. > > > =C2=A0 3. Client2 opens *file2* and also receives a write delegation > > > =C2=A0 =C2=A0 =C2=A0(*delegation2*). > > > =C2=A0 4. Client1 then issues an open request with CLAIM_DELEGATE_CUR= , > > > =C2=A0 =C2=A0 =C2=A0providing the filename from step 3 *(file2*), but= using the > > > =C2=A0 =C2=A0 =C2=A0delegation stateid from step 1 (*delegation1*). > >=20 > > Would that be a client bug? > >=20 > >=20 > > > =C2=A0 5. The server begins a recall of *delegation2*, treating the r= equest in > > > =C2=A0 =C2=A0 =C2=A0step 4 as a normal open rather than returning a B= AD_STATEID error. > >=20 > > That seems OK to me. The server has correctly noticed that the > > client is opening file2, and delegation2 is associated with a > > previous open of file2. > >=20 > > A better place to seek an authoritative answer might be RFC 8881. > >=20 > > The server returns BAD_STATEID if the stateid doesn't pass various > > checks as outlined in Section 8.2. I don't see any text requiring the > > server to report BAD_STATEID if delegate_stateid does not match the > > component4 on a DELEGATE_CUR OPEN -- in fact, Table 19 says that > > DELEGATE_CUR considers only the current file handle (the parent > > directory) and the component4 argument. > >=20 > >=20 > > > My understanding is that the server should have verified whether the > > > delegation stateid provided actually belongs to the file being opened= . > > > Since it does not, I expected the server to return a BAD_STATEID erro= r > > > instead of proceeding with a standard open. > > >=20 > > > From additional tests, it seems the server only checks whether the > > > delegation stateid is valid (i.e., whether it was ever granted), but > > > does not verify that it is associated with the correct file or client= . > > > Please see the attached PCAP for reference. > > >=20 > > > Questions: > > >=20 > > > Is this behavior considered a bug? > > >=20 > > > Are there any known plans to address or fix this issue in future kern= el > > > versions? > >=20 > > AFAICT at the moment, NOTABUG > >=20 > >=20 --=20 Jeff Layton