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Message-ID: <0b14aee6b687501e5d4eb4f0e62928fbe016af40.camel@kernel.org>
Subject: Re: [PATCH v7 2/5] NFSD: add write_version to netlink command
From: Jeff Layton <jlayton@kernel.org>
To: Lorenzo Bianconi <lorenzo@kernel.org>, linux-nfs@vger.kernel.org
Cc: lorenzo.bianconi@redhat.com, chuck.lever@oracle.com, neilb@suse.de, 
	netdev@vger.kernel.org, kuba@kernel.org
Date: Thu, 11 Apr 2024 18:48:34 -0400
In-Reply-To: <bd85d1a774cb362ab9f70ac6a2af70d9ed7a309e.1712853394.git.lorenzo@kernel.org>
References: <cover.1712853393.git.lorenzo@kernel.org>
	 <bd85d1a774cb362ab9f70ac6a2af70d9ed7a309e.1712853394.git.lorenzo@kernel.org>
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On Thu, 2024-04-11 at 18:47 +0200, Lorenzo Bianconi wrote:
> Introduce write_version netlink command through a "declarative" interface=
.
> This patch introduces a change in behavior since for version-set userspac=
e
> is expected to provide a NFS major/minor version list it wants to enable
> while all the other ones will be disabled. (procfs write_version
> command implements imperative interface where the admin writes +3/-3 to
> enable/disable a single version.
>=20
> Tested-by: Jeff Layton <jlayton@kernel.org>
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
>  Documentation/netlink/specs/nfsd.yaml |  37 +++++++
>  fs/nfsd/netlink.c                     |  24 ++++
>  fs/nfsd/netlink.h                     |   5 +
>  fs/nfsd/netns.h                       |   1 +
>  fs/nfsd/nfsctl.c                      | 153 ++++++++++++++++++++++++++
>  fs/nfsd/nfssvc.c                      |   3 +-
>  include/uapi/linux/nfsd_netlink.h     |  18 +++
>  7 files changed, 239 insertions(+), 2 deletions(-)
>=20
> diff --git a/Documentation/netlink/specs/nfsd.yaml b/Documentation/netlin=
k/specs/nfsd.yaml
> index c92e1425d316..cb93e3e37119 100644
> --- a/Documentation/netlink/specs/nfsd.yaml
> +++ b/Documentation/netlink/specs/nfsd.yaml
> @@ -68,6 +68,26 @@ attribute-sets:
>        -
>          name: threads
>          type: u32
> +  -
> +    name: version
> +    attributes:
> +      -
> +        name: major
> +        type: u32
> +      -
> +        name: minor
> +        type: u32
> +      -
> +        name: enabled
> +        type: flag
> +  -
> +    name: server-proto
> +    attributes:
> +      -
> +        name: version
> +        type: nest
> +        nested-attributes: version
> +        multi-attr: true
> =20
>  operations:
>    list:
> @@ -110,3 +130,20 @@ operations:
>          reply:
>            attributes:
>              - threads
> +    -
> +      name: version-set
> +      doc: set nfs enabled versions
> +      attribute-set: server-proto
> +      flags: [ admin-perm ]
> +      do:
> +        request:
> +          attributes:
> +            - version
> +    -
> +      name: version-get
> +      doc: get nfs enabled versions
> +      attribute-set: server-proto
> +      do:
> +        reply:
> +          attributes:
> +            - version
> diff --git a/fs/nfsd/netlink.c b/fs/nfsd/netlink.c
> index 1a59a8e6c7e2..75f609b57ceb 100644
> --- a/fs/nfsd/netlink.c
> +++ b/fs/nfsd/netlink.c
> @@ -10,11 +10,23 @@
> =20
>  #include <uapi/linux/nfsd_netlink.h>
> =20
> +/* Common nested types */
> +const struct nla_policy nfsd_version_nl_policy[NFSD_A_VERSION_ENABLED + =
1] =3D {
> +	[NFSD_A_VERSION_MAJOR] =3D { .type =3D NLA_U32, },
> +	[NFSD_A_VERSION_MINOR] =3D { .type =3D NLA_U32, },
> +	[NFSD_A_VERSION_ENABLED] =3D { .type =3D NLA_FLAG, },
> +};
> +
>  /* NFSD_CMD_THREADS_SET - do */
>  static const struct nla_policy nfsd_threads_set_nl_policy[NFSD_A_SERVER_=
WORKER_THREADS + 1] =3D {
>  	[NFSD_A_SERVER_WORKER_THREADS] =3D { .type =3D NLA_U32, },
>  };
> =20
> +/* NFSD_CMD_VERSION_SET - do */
> +static const struct nla_policy nfsd_version_set_nl_policy[NFSD_A_SERVER_=
PROTO_VERSION + 1] =3D {
> +	[NFSD_A_SERVER_PROTO_VERSION] =3D NLA_POLICY_NESTED(nfsd_version_nl_pol=
icy),
> +};
> +
>  /* Ops table for nfsd */
>  static const struct genl_split_ops nfsd_nl_ops[] =3D {
>  	{
> @@ -36,6 +48,18 @@ static const struct genl_split_ops nfsd_nl_ops[] =3D {
>  		.doit	=3D nfsd_nl_threads_get_doit,
>  		.flags	=3D GENL_CMD_CAP_DO,
>  	},
> +	{
> +		.cmd		=3D NFSD_CMD_VERSION_SET,
> +		.doit		=3D nfsd_nl_version_set_doit,
> +		.policy		=3D nfsd_version_set_nl_policy,
> +		.maxattr	=3D NFSD_A_SERVER_PROTO_VERSION,
> +		.flags		=3D GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
> +	},
> +	{
> +		.cmd	=3D NFSD_CMD_VERSION_GET,
> +		.doit	=3D nfsd_nl_version_get_doit,
> +		.flags	=3D GENL_CMD_CAP_DO,
> +	},
>  };
> =20
>  struct genl_family nfsd_nl_family __ro_after_init =3D {
> diff --git a/fs/nfsd/netlink.h b/fs/nfsd/netlink.h
> index 4137fac477e4..c7c0da275481 100644
> --- a/fs/nfsd/netlink.h
> +++ b/fs/nfsd/netlink.h
> @@ -11,6 +11,9 @@
> =20
>  #include <uapi/linux/nfsd_netlink.h>
> =20
> +/* Common nested types */
> +extern const struct nla_policy nfsd_version_nl_policy[NFSD_A_VERSION_ENA=
BLED + 1];
> +
>  int nfsd_nl_rpc_status_get_start(struct netlink_callback *cb);
>  int nfsd_nl_rpc_status_get_done(struct netlink_callback *cb);
> =20
> @@ -18,6 +21,8 @@ int nfsd_nl_rpc_status_get_dumpit(struct sk_buff *skb,
>  				  struct netlink_callback *cb);
>  int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *info=
);
>  int nfsd_nl_threads_get_doit(struct sk_buff *skb, struct genl_info *info=
);
> +int nfsd_nl_version_set_doit(struct sk_buff *skb, struct genl_info *info=
);
> +int nfsd_nl_version_get_doit(struct sk_buff *skb, struct genl_info *info=
);
> =20
>  extern struct genl_family nfsd_nl_family;
> =20
> diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
> index d4be519b5734..14ec15656320 100644
> --- a/fs/nfsd/netns.h
> +++ b/fs/nfsd/netns.h
> @@ -218,6 +218,7 @@ struct nfsd_net {
>  /* Simple check to find out if a given net was properly initialized */
>  #define nfsd_netns_ready(nn) ((nn)->sessionid_hashtbl)
> =20
> +extern bool nfsd_support_version(int vers);
>  extern void nfsd_netns_free_versions(struct nfsd_net *nn);
> =20
>  extern unsigned int nfsd_net_id;
> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> index 71608744e67f..341efab4eaa7 100644
> --- a/fs/nfsd/nfsctl.c
> +++ b/fs/nfsd/nfsctl.c
> @@ -1711,6 +1711,159 @@ int nfsd_nl_threads_get_doit(struct sk_buff *skb,=
 struct genl_info *info)
>  	return err;
>  }
> =20
> +/**
> + * nfsd_nl_version_set_doit - set the nfs enabled versions
> + * @skb: reply buffer
> + * @info: netlink metadata and command arguments
> + *
> + * Return 0 on success or a negative errno.
> + */
> +int nfsd_nl_version_set_doit(struct sk_buff *skb, struct genl_info *info=
)
> +{
> +	const struct nlattr *attr;
> +	struct nfsd_net *nn;
> +	int i, rem;
> +
> +	if (GENL_REQ_ATTR_CHECK(info, NFSD_A_SERVER_PROTO_VERSION))
> +		return -EINVAL;
> +
> +	mutex_lock(&nfsd_mutex);
> +
> +	nn =3D net_generic(genl_info_net(info), nfsd_net_id);
> +	if (nn->nfsd_serv) {
> +		mutex_unlock(&nfsd_mutex);
> +		return -EBUSY;
> +	}
> +
> +	/* clear current supported versions. */
> +	nfsd_vers(nn, 2, NFSD_CLEAR);
> +	nfsd_vers(nn, 3, NFSD_CLEAR);
> +	for (i =3D 0; i <=3D NFSD_SUPPORTED_MINOR_VERSION; i++)
> +		nfsd_minorversion(nn, i, NFSD_CLEAR);
> +
> +	nlmsg_for_each_attr(attr, info->nlhdr, GENL_HDRLEN, rem) {
> +		struct nlattr *tb[NFSD_A_VERSION_MAX + 1];
> +		u32 major, minor =3D 0;
> +		bool enabled;
> +
> +		if (nla_type(attr) !=3D NFSD_A_SERVER_PROTO_VERSION)
> +			continue;
> +
> +		if (nla_parse_nested(tb, NFSD_A_VERSION_MAX, attr,
> +				     nfsd_version_nl_policy, info->extack) < 0)
> +			continue;
> +
> +		if (!tb[NFSD_A_VERSION_MAJOR])
> +			continue;
> +
> +		major =3D nla_get_u32(tb[NFSD_A_VERSION_MAJOR]);
> +		if (tb[NFSD_A_VERSION_MINOR])
> +			minor =3D nla_get_u32(tb[NFSD_A_VERSION_MINOR]);
> +
> +		enabled =3D nla_get_flag(tb[NFSD_A_VERSION_ENABLED]);
> +
> +		switch (major) {
> +		case 4:
> +			nfsd_minorversion(nn, minor, enabled ? NFSD_SET : NFSD_CLEAR);
> +			break;
> +		case 3:
> +		case 2:
> +			if (!minor)
> +				nfsd_vers(nn, major, enabled ? NFSD_SET : NFSD_CLEAR);
> +			break;
> +		default:
> +			break;
> +		}
> +	}
> +
> +	mutex_unlock(&nfsd_mutex);
> +
> +	return 0;
> +}
> +
> +/**
> + * nfsd_nl_version_get_doit - get the nfs enabled versions
> + * @skb: reply buffer
> + * @info: netlink metadata and command arguments
> + *
> + * Return 0 on success or a negative errno.
> + */
> +int nfsd_nl_version_get_doit(struct sk_buff *skb, struct genl_info *info=
)
> +{
> +	struct nfsd_net *nn;
> +	int i, err;
> +	void *hdr;
> +
> +	skb =3D genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
> +	if (!skb)
> +		return -ENOMEM;
> +
> +	hdr =3D genlmsg_iput(skb, info);
> +	if (!hdr) {
> +		err =3D -EMSGSIZE;
> +		goto err_free_msg;
> +	}
> +
> +	mutex_lock(&nfsd_mutex);
> +	nn =3D net_generic(genl_info_net(info), nfsd_net_id);
> +
> +	for (i =3D 2; i <=3D 4; i++) {
> +		int j;
> +
> +		for (j =3D 0; j <=3D NFSD_SUPPORTED_MINOR_VERSION; j++) {
> +			struct nlattr *attr;
> +
> +			/* Don't record any versions the kernel doesn't have
> +			 * compiled in
> +			 */
> +			if (!nfsd_support_version(i))
> +				continue;
> +
> +			/* NFSv{2,3} does not support minor numbers */
> +			if (i < 4 && j)
> +				continue;
> +
> +			if (i =3D=3D 4 && !nfsd_minorversion(nn, j, NFSD_TEST))
> +				continue;
> +

I think this is not quite right. We don't want to skip returning a
minorversion just because it's not enabled. We want to return the entry
with the enabled flag cleared. I'd suggest just dropping the above if
statement entirely.

> +			attr =3D nla_nest_start_noflag(skb,
> +					NFSD_A_SERVER_PROTO_VERSION);
> +			if (!attr) {
> +				err =3D -EINVAL;
> +				goto err_nfsd_unlock;
> +			}
> +
> +			if (nla_put_u32(skb, NFSD_A_VERSION_MAJOR, i) ||
> +			    nla_put_u32(skb, NFSD_A_VERSION_MINOR, j)) {
> +				err =3D -EINVAL;
> +				goto err_nfsd_unlock;
> +			}
> +
> +			/* Set the enabled flag if the version is enabled */
> +			if (nfsd_vers(nn, i, NFSD_TEST) &&
> +			    (i < 4 || nfsd_minorversion(nn, j, NFSD_TEST)) &&
> +			    nla_put_flag(skb, NFSD_A_VERSION_ENABLED)) {
> +				err =3D -EINVAL;
> +				goto err_nfsd_unlock;
> +			}
> +
> +			nla_nest_end(skb, attr);
> +		}
> +	}
> +
> +	mutex_unlock(&nfsd_mutex);
> +	genlmsg_end(skb, hdr);
> +
> +	return genlmsg_reply(skb, info);
> +
> +err_nfsd_unlock:
> +	mutex_unlock(&nfsd_mutex);
> +err_free_msg:
> +	nlmsg_free(skb);
> +
> +	return err;
> +}
> +
>  /**
>   * nfsd_net_init - Prepare the nfsd_net portion of a new net namespace
>   * @net: a freshly-created network namespace
> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
> index c0d17b92b249..4452a9bb9bbb 100644
> --- a/fs/nfsd/nfssvc.c
> +++ b/fs/nfsd/nfssvc.c
> @@ -133,8 +133,7 @@ struct svc_program		nfsd_program =3D {
>  	.pg_rpcbind_set		=3D nfsd_rpcbind_set,
>  };
> =20
> -static bool
> -nfsd_support_version(int vers)
> +bool nfsd_support_version(int vers)
>  {
>  	if (vers >=3D NFSD_MINVERS && vers < NFSD_NRVERS)
>  		return nfsd_version[vers] !=3D NULL;
> diff --git a/include/uapi/linux/nfsd_netlink.h b/include/uapi/linux/nfsd_=
netlink.h
> index 1b6fe1f9ed0e..ccf3e15fe160 100644
> --- a/include/uapi/linux/nfsd_netlink.h
> +++ b/include/uapi/linux/nfsd_netlink.h
> @@ -36,10 +36,28 @@ enum {
>  	NFSD_A_SERVER_WORKER_MAX =3D (__NFSD_A_SERVER_WORKER_MAX - 1)
>  };
> =20
> +enum {
> +	NFSD_A_VERSION_MAJOR =3D 1,
> +	NFSD_A_VERSION_MINOR,
> +	NFSD_A_VERSION_ENABLED,
> +
> +	__NFSD_A_VERSION_MAX,
> +	NFSD_A_VERSION_MAX =3D (__NFSD_A_VERSION_MAX - 1)
> +};
> +
> +enum {
> +	NFSD_A_SERVER_PROTO_VERSION =3D 1,
> +
> +	__NFSD_A_SERVER_PROTO_MAX,
> +	NFSD_A_SERVER_PROTO_MAX =3D (__NFSD_A_SERVER_PROTO_MAX - 1)
> +};
> +
>  enum {
>  	NFSD_CMD_RPC_STATUS_GET =3D 1,
>  	NFSD_CMD_THREADS_SET,
>  	NFSD_CMD_THREADS_GET,
> +	NFSD_CMD_VERSION_SET,
> +	NFSD_CMD_VERSION_GET,
> =20
>  	__NFSD_CMD_MAX,
>  	NFSD_CMD_MAX =3D (__NFSD_CMD_MAX - 1)

--=20
Jeff Layton <jlayton@kernel.org>