Re: [PATCH v3 3/3] nfsd: allow disabling NFSv2 at compile time

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2022-10-19 at 11:09 -0400, Tom Talpey wrote:
> LGTM
> 
> Reviewed-by: Tom Talpey <tom@talpey.com>
> 
> Next, to make it a module!
> 

We could, but I'm not sure it's worthwhile. We'd need to export about 15
symbols from nfsd.ko. Personally I'd rather see it just go away
eventually.

> On 10/18/2022 7:47 AM, Jeff Layton wrote:
> > rpc.nfsd stopped supporting NFSv2 a year ago. Take the next logical
> > step toward deprecating it and allow NFSv2 support to be compiled out.
> > 
> > Add a new CONFIG_NFSD_V2 option that can be turned off and rework the
> > CONFIG_NFSD_V?_ACL option dependencies. Add a description that
> > discourages enabling it.
> > 
> > Also, change the description of CONFIG_NFSD to state that the always-on
> > version is now 3 instead of 2.
> > 
> > Finally, add an #ifdef around "case 2:" in __write_versions. When NFSv2
> > is disabled at compile time, this should make the kernel ignore attempts
> > to disable it at runtime, but still error out when trying to enable it.
> > 
> > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > ---
> >   fs/nfsd/Kconfig  | 19 +++++++++++++++----
> >   fs/nfsd/Makefile |  5 +++--
> >   fs/nfsd/nfsctl.c |  2 ++
> >   fs/nfsd/nfsd.h   |  3 +--
> >   fs/nfsd/nfssvc.c |  6 ++++++
> >   5 files changed, 27 insertions(+), 8 deletions(-)
> > 
> > diff --git a/fs/nfsd/Kconfig b/fs/nfsd/Kconfig
> > index f6a2fd3015e7..7c441f2bd444 100644
> > --- a/fs/nfsd/Kconfig
> > +++ b/fs/nfsd/Kconfig
> > @@ -8,6 +8,7 @@ config NFSD
> >   	select SUNRPC
> >   	select EXPORTFS
> >   	select NFS_ACL_SUPPORT if NFSD_V2_ACL
> > +	select NFS_ACL_SUPPORT if NFSD_V3_ACL
> >   	depends on MULTIUSER
> >   	help
> >   	  Choose Y here if you want to allow other computers to access
> > @@ -26,19 +27,29 @@ config NFSD
> >   
> >   	  Below you can choose which versions of the NFS protocol are
> >   	  available to clients mounting the NFS server on this system.
> > -	  Support for NFS version 2 (RFC 1094) is always available when
> > +	  Support for NFS version 3 (RFC 1813) is always available when
> >   	  CONFIG_NFSD is selected.
> >   
> >   	  If unsure, say N.
> >   
> > -config NFSD_V2_ACL
> > -	bool
> > +config NFSD_V2
> > +	bool "NFS server support for NFS version 2 (DEPRECATED)"
> >   	depends on NFSD
> > +	default n
> > +	help
> > +	  NFSv2 (RFC 1094) was the first publicly-released version of NFS.
> > +	  Unless you are hosting ancient (1990's era) NFS clients, you don't
> > +	  need this.
> > +
> > +	  If unsure, say N.
> > +
> > +config NFSD_V2_ACL
> > +	bool "NFS server support for the NFSv2 ACL protocol extension"
> > +	depends on NFSD_V2
> >   
> >   config NFSD_V3_ACL
> >   	bool "NFS server support for the NFSv3 ACL protocol extension"
> >   	depends on NFSD
> > -	select NFSD_V2_ACL
> >   	help
> >   	  Solaris NFS servers support an auxiliary NFSv3 ACL protocol that
> >   	  never became an official part of the NFS version 3 protocol.
> > diff --git a/fs/nfsd/Makefile b/fs/nfsd/Makefile
> > index 805c06d5f1b4..6fffc8f03f74 100644
> > --- a/fs/nfsd/Makefile
> > +++ b/fs/nfsd/Makefile
> > @@ -10,9 +10,10 @@ obj-$(CONFIG_NFSD)	+= nfsd.o
> >   # this one should be compiled first, as the tracing macros can easily blow up
> >   nfsd-y			+= trace.o
> >   
> > -nfsd-y 			+= nfssvc.o nfsctl.o nfsproc.o nfsfh.o vfs.o \
> > -			   export.o auth.o lockd.o nfscache.o nfsxdr.o \
> > +nfsd-y 			+= nfssvc.o nfsctl.o nfsfh.o vfs.o \
> > +			   export.o auth.o lockd.o nfscache.o \
> >   			   stats.o filecache.o nfs3proc.o nfs3xdr.o
> > +nfsd-$(CONFIG_NFSD_V2) += nfsproc.o nfsxdr.o
> >   nfsd-$(CONFIG_NFSD_V2_ACL) += nfs2acl.o
> >   nfsd-$(CONFIG_NFSD_V3_ACL) += nfs3acl.o
> >   nfsd-$(CONFIG_NFSD_V4)	+= nfs4proc.o nfs4xdr.o nfs4state.o nfs4idmap.o \
> > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> > index 68ed42fd29fc..d1e581a60480 100644
> > --- a/fs/nfsd/nfsctl.c
> > +++ b/fs/nfsd/nfsctl.c
> > @@ -581,7 +581,9 @@ static ssize_t __write_versions(struct file *file, char *buf, size_t size)
> >   
> >   			cmd = sign == '-' ? NFSD_CLEAR : NFSD_SET;
> >   			switch(num) {
> > +#ifdef CONFIG_NFSD_V2
> >   			case 2:
> > +#endif
> >   			case 3:
> >   				nfsd_vers(nn, num, cmd);
> >   				break;
> > diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> > index 09726c5b9a31..93b42ef9ed91 100644
> > --- a/fs/nfsd/nfsd.h
> > +++ b/fs/nfsd/nfsd.h
> > @@ -64,8 +64,7 @@ struct readdir_cd {
> >   
> >   
> >   extern struct svc_program	nfsd_program;
> > -extern const struct svc_version	nfsd_version2, nfsd_version3,
> > -				nfsd_version4;
> > +extern const struct svc_version	nfsd_version2, nfsd_version3, nfsd_version4;
> >   extern struct mutex		nfsd_mutex;
> >   extern spinlock_t		nfsd_drc_lock;
> >   extern unsigned long		nfsd_drc_max_mem;
> > diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
> > index bfbd9f672f59..62e473b0ca52 100644
> > --- a/fs/nfsd/nfssvc.c
> > +++ b/fs/nfsd/nfssvc.c
> > @@ -91,8 +91,12 @@ unsigned long	nfsd_drc_mem_used;
> >   #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
> >   static struct svc_stat	nfsd_acl_svcstats;
> >   static const struct svc_version *nfsd_acl_version[] = {
> > +# if defined(CONFIG_NFSD_V2_ACL)
> >   	[2] = &nfsd_acl_version2,
> > +# endif
> > +# if defined(CONFIG_NFSD_V3_ACL)
> >   	[3] = &nfsd_acl_version3,
> > +# endif
> >   };
> >   
> >   #define NFSD_ACL_MINVERS            2
> > @@ -116,7 +120,9 @@ static struct svc_stat	nfsd_acl_svcstats = {
> >   #endif /* defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) */
> >   
> >   static const struct svc_version *nfsd_version[] = {
> > +#if defined(CONFIG_NFSD_V2)
> >   	[2] = &nfsd_version2,
> > +#endif
> >   	[3] = &nfsd_version3,
> >   #if defined(CONFIG_NFSD_V4)
> >   	[4] = &nfsd_version4,

-- 
Jeff Layton <jlayton@kernel.org>