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Message-ID: <20240912224744.e5lb6j53wldxvfdm@pali>
Date: Fri, 13 Sep 2024 00:47:44 +0200
From: Pali Rohár <pali@...nel.org>
To: NeilBrown <neilb@...e.de>
Cc: Chuck Lever <chuck.lever@...cle.com>, Jeff Layton <jlayton@...nel.org>,
Olga Kornievskaia <okorniev@...hat.com>,
Dai Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>,
linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nfsd: Fill NFSv4.1 server implementation fields in
OP_EXCHANGE_ID response
On Friday 13 September 2024 08:31:55 NeilBrown wrote:
> On Fri, 13 Sep 2024, Pali Rohár wrote:
> > NFSv4.1 OP_EXCHANGE_ID response from server may contain server
> > implementation details (domain, name and build time) in optional
> > nfs_impl_id4 field. Currently nfsd does not fill this field.
> >
> > NFSv4.1 OP_EXCHANGE_ID call request from client may contain client
> > implementation details and Linux NFSv4.1 client is already filling these
> > information based on runtime module param "nfs.send_implementation_id" and
> > build time Kconfig option "NFS_V4_1_IMPLEMENTATION_ID_DOMAIN". Module param
> > send_implementation_id specify whether to fill implementation fields and
> > Kconfig option "NFS_V4_1_IMPLEMENTATION_ID_DOMAIN" specify the domain
> > string.
> >
> > Do same in nfsd, introduce new runtime param "nfsd.send_implementation_id"
> > and build time Kconfig option "NFSD_V4_1_IMPLEMENTATION_ID_DOMAIN" and
> > based on them fill NFSv4.1 server implementation details in OP_EXCHANGE_ID
> > response. Logic in nfsd is exactly same as in nfs.
> >
> > This aligns Linux NFSv4.1 server logic with Linux NFSv4.1 client logic.
> >
> > NFSv4.1 client and server implementation fields are useful for statistic
> > purposes or for identifying type of clients and servers.
> >
> > Signed-off-by: Pali Rohár <pali@...nel.org>
> > ---
> > fs/nfsd/Kconfig | 12 +++++++++++
> > fs/nfsd/nfs4xdr.c | 55 +++++++++++++++++++++++++++++++++++++++++++++--
> > 2 files changed, 65 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/nfsd/Kconfig b/fs/nfsd/Kconfig
> > index ec2ab6429e00..70067c29316e 100644
> > --- a/fs/nfsd/Kconfig
> > +++ b/fs/nfsd/Kconfig
> > @@ -136,6 +136,18 @@ config NFSD_FLEXFILELAYOUT
> >
> > If unsure, say N.
> >
> > +config NFSD_V4_1_IMPLEMENTATION_ID_DOMAIN
> > + string "NFSv4.1 Implementation ID Domain"
> > + depends on NFSD_V4
> > + default "kernel.org"
> > + help
> > + This option defines the domain portion of the implementation ID that
> > + may be sent in the NFS exchange_id operation. The value must be in
> > + the format of a DNS domain name and should be set to the DNS domain
> > + name of the distribution.
> > + If the NFS server is unchanged from the upstream kernel, this
> > + option should be set to the default "kernel.org".
> > +
> > config NFSD_V4_2_INTER_SSC
> > bool "NFSv4.2 inter server to server COPY"
> > depends on NFSD_V4 && NFS_V4_2
> > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> > index b45ea5757652..5e89f999d4c7 100644
> > --- a/fs/nfsd/nfs4xdr.c
> > +++ b/fs/nfsd/nfs4xdr.c
> > @@ -62,6 +62,9 @@
> > #include <linux/security.h>
> > #endif
> >
> > +static bool send_implementation_id = true;
> > +module_param(send_implementation_id, bool, 0644);
> > +MODULE_PARM_DESC(send_implementation_id, "Send implementation ID with NFSv4.1 exchange_id");
> >
> > #define NFSDDBG_FACILITY NFSDDBG_XDR
> >
> > @@ -4833,6 +4836,53 @@ nfsd4_encode_server_owner4(struct xdr_stream *xdr, struct svc_rqst *rqstp)
> > return nfsd4_encode_opaque(xdr, nn->nfsd_name, strlen(nn->nfsd_name));
> > }
> >
> > +#define IMPL_NAME_LIMIT (sizeof(utsname()->sysname) + sizeof(utsname()->release) + \
> > + sizeof(utsname()->version) + sizeof(utsname()->machine) + 8)
>
> This "+8" seems strange. In the xdr_reserve_space() call below you are
> very thorough about explaining the magic numbers - which is great. Here
> that is this unexplained 8.
I copied this code from nfs/nfs4xdr.c file. And verified in wireshark
that packets were correctly constructed.
> I don't think you need +8 at all. sizeof(string) will give room to
> print the string plus a trailing space or nul, and that is all you need.
I'm looking at it, and I think you are right, +8 should not be needed.
Thanks for review.
> Otherwise the patch looks OK.
>
> Thanks,
> NeilBrown
>
>
> > +
> > +static __be32
> > +nfsd4_encode_server_impl_id(struct xdr_stream *xdr)
> > +{
> > + char impl_name[IMPL_NAME_LIMIT];
> > + int impl_name_len;
> > + __be32 *p;
> > +
> > + impl_name_len = 0;
> > + if (send_implementation_id &&
> > + sizeof(CONFIG_NFSD_V4_1_IMPLEMENTATION_ID_DOMAIN) > 1 &&
> > + sizeof(CONFIG_NFSD_V4_1_IMPLEMENTATION_ID_DOMAIN) <= NFS4_OPAQUE_LIMIT)
> > + impl_name_len = snprintf(impl_name, sizeof(impl_name), "%s %s %s %s",
> > + utsname()->sysname, utsname()->release,
> > + utsname()->version, utsname()->machine);
> > +
> > + if (impl_name_len <= 0) {
> > + if (xdr_stream_encode_u32(xdr, 0) != XDR_UNIT)
> > + return nfserr_resource;
> > + return nfs_ok;
> > + }
> > +
> > + if (xdr_stream_encode_u32(xdr, 1) != XDR_UNIT)
> > + return nfserr_resource;
> > +
> > + p = xdr_reserve_space(xdr,
> > + 4 /* nii_domain.len */ +
> > + (XDR_QUADLEN(sizeof(CONFIG_NFSD_V4_1_IMPLEMENTATION_ID_DOMAIN) - 1) * 4) +
> > + 4 /* nii_name.len */ +
> > + (XDR_QUADLEN(impl_name_len) * 4) +
> > + 8 /* nii_time.tv_sec */ +
> > + 4 /* nii_time.tv_nsec */);
> > + if (!p)
> > + return nfserr_resource;
> > +
> > + p = xdr_encode_opaque(p, CONFIG_NFSD_V4_1_IMPLEMENTATION_ID_DOMAIN,
> > + sizeof(CONFIG_NFSD_V4_1_IMPLEMENTATION_ID_DOMAIN) - 1);
> > + p = xdr_encode_opaque(p, impl_name, impl_name_len);
> > + /* just send zeros for nii_date - the date is in nii_name */
> > + p = xdr_encode_hyper(p, 0); /* tv_sec */
> > + *p++ = cpu_to_be32(0); /* tv_nsec */
> > +
> > + return nfs_ok;
> > +}
> > +
> > static __be32
> > nfsd4_encode_exchange_id(struct nfsd4_compoundres *resp, __be32 nfserr,
> > union nfsd4_op_u *u)
> > @@ -4867,8 +4917,9 @@ nfsd4_encode_exchange_id(struct nfsd4_compoundres *resp, __be32 nfserr,
> > if (nfserr != nfs_ok)
> > return nfserr;
> > /* eir_server_impl_id<1> */
> > - if (xdr_stream_encode_u32(xdr, 0) != XDR_UNIT)
> > - return nfserr_resource;
> > + nfserr = nfsd4_encode_server_impl_id(xdr);
> > + if (nfserr != nfs_ok)
> > + return nfserr;
> >
> > return nfs_ok;
> > }
> > --
> > 2.20.1
> >
> >
>
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