Re: [PATCH v7 1/3 RESEND] block:sed-opal: SED Opal keystore

[Nathan Chancellor <nathan@kernel.org>]

On Wed, Sep 13, 2023 at 01:49:39PM -0700, Nick Desaulniers wrote:
> On Wed, Sep 13, 2023 at 9:56 AM Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > Hi Greg,
> >
> > On Fri, Sep 08, 2023 at 10:30:54AM -0500, gjoyce@linux.vnet.ibm.com wrote:
> > > From: Greg Joyce <gjoyce@linux.vnet.ibm.com>
> > >
> > > Add read and write functions that allow SED Opal keys to stored
> > > in a permanent keystore.
> > >
> > > Signed-off-by: Greg Joyce <gjoyce@linux.vnet.ibm.com>
> > > Reviewed-by: Jonathan Derrick <jonathan.derrick@linux.dev>
> > > ---
> > >  block/Makefile               |  2 +-
> > >  block/sed-opal-key.c         | 24 ++++++++++++++++++++++++
> > >  include/linux/sed-opal-key.h | 15 +++++++++++++++
> > >  3 files changed, 40 insertions(+), 1 deletion(-)
> > >  create mode 100644 block/sed-opal-key.c
> > >  create mode 100644 include/linux/sed-opal-key.h
> > >
> > > diff --git a/block/Makefile b/block/Makefile
> > > index 46ada9dc8bbf..ea07d80402a6 100644
> > > --- a/block/Makefile
> > > +++ b/block/Makefile
> > > @@ -34,7 +34,7 @@ obj-$(CONFIG_BLK_DEV_ZONED) += blk-zoned.o
> > >  obj-$(CONFIG_BLK_WBT)                += blk-wbt.o
> > >  obj-$(CONFIG_BLK_DEBUG_FS)   += blk-mq-debugfs.o
> > >  obj-$(CONFIG_BLK_DEBUG_FS_ZONED)+= blk-mq-debugfs-zoned.o
> > > -obj-$(CONFIG_BLK_SED_OPAL)   += sed-opal.o
> > > +obj-$(CONFIG_BLK_SED_OPAL)   += sed-opal.o sed-opal-key.o
> > >  obj-$(CONFIG_BLK_PM)         += blk-pm.o
> > >  obj-$(CONFIG_BLK_INLINE_ENCRYPTION)  += blk-crypto.o blk-crypto-profile.o \
> > >                                          blk-crypto-sysfs.o
> > > diff --git a/block/sed-opal-key.c b/block/sed-opal-key.c
> > > new file mode 100644
> > > index 000000000000..16f380164c44
> > > --- /dev/null
> > > +++ b/block/sed-opal-key.c
> > > @@ -0,0 +1,24 @@
> > > +// SPDX-License-Identifier: GPL-2.0-only
> > > +/*
> > > + * SED key operations.
> > > + *
> > > + * Copyright (C) 2022 IBM Corporation
> > > + *
> > > + * These are the accessor functions (read/write) for SED Opal
> > > + * keys. Specific keystores can provide overrides.
> > > + *
> > > + */
> > > +
> > > +#include <linux/kernel.h>
> > > +#include <linux/errno.h>
> > > +#include <linux/sed-opal-key.h>
> > > +
> > > +int __weak sed_read_key(char *keyname, char *key, u_int *keylen)
> > > +{
> > > +     return -EOPNOTSUPP;
> > > +}
> > > +
> > > +int __weak sed_write_key(char *keyname, char *key, u_int keylen)
> > > +{
> > > +     return -EOPNOTSUPP;
> > > +}
> >
> > This change causes a build failure for certain clang configurations due
> > to an unfortunate issue [1] with recordmcount, clang's integrated
> > assembler, and object files that contain a section with only weak
> > functions/symbols (in this case, the .text section in sed-opal-key.c),
> > resulting in
> >
> >   Cannot find symbol for section 2: .text.
> >   block/sed-opal-key.o: failed
> >
> > when building this file.
> 
> The definitions in
> block/sed-opal-key.c
> should be deleted. Instead, in
> include/linux/sed-opal-key.h
> CONFIG_PSERIES_PLPKS_SED should be used to define static inline
> versions when CONFIG_PSERIES_PLPKS_SED is not defined.
> 
> #ifdef CONFIG_PSERIES_PLPKS_SED
> int sed_read_key(char *keyname, char *key, u_int *keylen);
> int sed_write_key(char *keyname, char *key, u_int keylen);
> #else
> static inline
> int sed_read_key(char *keyname, char *key, u_int *keylen) {
>   return -EOPNOTSUPP;
> }
> static inline
> int sed_write_key(char *keyname, char *key, u_int keylen);
>   return -EOPNOTSUPP;
> }
> #endif

Ah yes, this is the other solution. I figured the way that it was
written, sed_read_key() and sed_write_key() may be overridden by a
different architecture or translation unit in the future but I think
until it is needed, your solution would be perfectly fine. Thanks for
taking a look!

Cheers,
Nathan

> > Is there any real reason to have a separate translation unit for these
> > two functions versus just having them living in sed-opal.c? Those two
> > object files share the same Kconfig dependency. I am happy to send a
> > patch if that is an acceptable approach.
> >
> > [1]: https://github.com/ClangBuiltLinux/linux/issues/981
> >
> > Cheers,
> > Nathan
> >
> 
> 
> -- 
> Thanks,
> ~Nick Desaulniers