From mboxrd@z Thu Jan 1 00:00:00 1970 From: "J. Bruce Fields" Subject: Re: [PATCH 06/15] NFSv4: Introduce new label structure Date: Tue, 12 Feb 2013 17:32:26 -0500 Message-ID: <20130212223226.GL10267@fieldses.org> References: <1360327163-20360-1-git-send-email-SteveD@redhat.com> <1360327163-20360-7-git-send-email-SteveD@redhat.com> <20130212220741.GJ10267@fieldses.org> <4FA345DA4F4AE44899BD2B03EEEC2FA91F3CE55C@sacexcmbx05-prd.hq.netapp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Steve Dickson , "J. Bruce Fields" , "David P. Quigley" , Linux NFS list , Linux FS devel list , Linux Security List , SELinux List To: "Myklebust, Trond" Return-path: Content-Disposition: inline In-Reply-To: <4FA345DA4F4AE44899BD2B03EEEC2FA91F3CE55C@sacexcmbx05-prd.hq.netapp.com> Sender: linux-security-module-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue, Feb 12, 2013 at 10:28:16PM +0000, Myklebust, Trond wrote: > On Tue, 2013-02-12 at 17:07 -0500, J. Bruce Fields wrote: > > On Fri, Feb 08, 2013 at 07:39:14AM -0500, Steve Dickson wrote: > > > From: David Quigley > > > > > > In order to mimic the way that NFSv4 ACLs are implemented we have created a > > > structure to be used to pass label data up and down the call chain. This patch > > > adds the new structure and new members to the required NFSv4 call structures. > > > > > > Signed-off-by: Matthew N. Dodd > > > Signed-off-by: Miguel Rodel Felipe > > > Signed-off-by: Phua Eu Gene > > > Signed-off-by: Khin Mi Mi Aung > > > --- > > > fs/nfs/inode.c | 33 +++++++++++++++++++++++++++++++++ > > > include/linux/nfs4.h | 7 +++++++ > > > include/linux/nfs_fs.h | 17 +++++++++++++++++ > > > include/linux/nfs_xdr.h | 21 +++++++++++++++++++++ > > > include/uapi/linux/nfs4.h | 2 +- > > > 5 files changed, 79 insertions(+), 1 deletion(-) > > > > > > diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c > > > index ebeb94c..8d5f01b 100644 > > > --- a/fs/nfs/inode.c > > > +++ b/fs/nfs/inode.c > > > @@ -255,6 +255,39 @@ nfs_init_locked(struct inode *inode, void *opaque) > > > return 0; > > > } > > > > > > +#ifdef CONFIG_NFS_V4_SECURITY_LABEL > > > +struct nfs4_label *nfs4_label_alloc(struct nfs_server *server, gfp_t flags) > > > +{ > > > + struct nfs4_label *label = NULL; > > > + > > > + if (!(server->caps & NFS_CAP_SECURITY_LABEL)) > > > + return label; > > > + > > > + label = kzalloc(NFS4_MAXLABELLEN, flags); > > > + if (label == NULL) > > > + return ERR_PTR(-ENOMEM); > > > + > > > + label->label = (char *)(label + 1); > > > + label->len = NFS4_MAXLABELLEN; > > > > If you're expecting to be able to store up to NFS4_MAXLABELLEN of data > > after the end of the struct, then you want: > > > > label = kzalloc(sizeof(struct nfs4_label) + NFS4_MAXLABELLEN, flags); > > Sigh... No. > > I keep telling Steve that the 'label' needs to be defined as an array, Yeah, I know, he said in 0/15 that he couldn't do that, so I've been reading through these on the assumption I'll find out why not at some point.... (Still not seeing it, though.) --b. > not a pointer. Having it be a pointer gives rise to a completely > unnecessary extra indirection (the CPU first needs to look up the > content of 'label->label', then dereference that pointer)... > > IOW: we should just be defining struct nfs4_label as > > struct nfs4_label { > > .... lots of definitions ... > > char label[NFS4_MAXLABELLEN]; > }; > > in which case the above allocation becomes a trivial > > label = kzalloc(sizeof(*label), flags); > > > > > > + > > > + return label; > > > +} > > > +EXPORT_SYMBOL_GPL(nfs4_label_alloc); > > > + > > > +void nfs4_label_init(struct nfs4_label *label) > > > +{ > > > + if (label && label->label) { > > > + /* 0 is the null format meaning that the data is not > > > + to be translated */ > > > + label->lfs = 0; > > > + label->pi = 0; > > > + label->len = NFS4_MAXLABELLEN; > > > > This logic seems a little odd to me; why would we pass NULL to this? > > Why would we skip the other initialization in the !label->label case? > > Why is NFS4_MAXLABELLEN the default? (And wasn't that just set in > > nfs4_label_alloc?) > > > > But OK maybe I need to read the rest of the patches. > > > > > + } > > > + return; > > > +} > > > +EXPORT_SYMBOL_GPL(nfs4_label_init); > > > +#endif > > > > > diff --git a/include/uapi/linux/nfs4.h b/include/uapi/linux/nfs4.h > > > index 788128e..b8014a2 100644 > > > --- a/include/uapi/linux/nfs4.h > > > +++ b/include/uapi/linux/nfs4.h > > > @@ -25,7 +25,7 @@ > > > #define NFS4_MAXNAMLEN NAME_MAX > > > #define NFS4_OPAQUE_LIMIT 1024 > > > #define NFS4_MAX_SESSIONID_LEN 16 > > > - > > > +#define NFS4_MAXLABELLEN (4095 - offsetof(struct nfs4_label , label)) > > > > The way you've defined things, that should be just > > > > (4095 - sizeof(struct nfs4_label)) > > No. See above. If the 'label' field is an array, then the offsetof() is > 100% correct. > > > (Is there typically some more alloc overhead that would push this > > allocation over 4k? I don't know well enough how the allocator(s) work > > to answer that.) > > > > --b. > > > > > #define NFS4_ACCESS_READ 0x0001 > > > #define NFS4_ACCESS_LOOKUP 0x0002 > > > #define NFS4_ACCESS_MODIFY 0x0004 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html