linux-kernel - Re: [PATCH 2/2] macsec: Netlink support of XPN cipher suites (IEEE 802.1AEbw)

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Date:   Fri, 6 Mar 2020 02:59:14 +0000
From:   Era Mayflower <mayflowerera@...il.com>
To:     Michal Kubecek <mkubecek@...e.cz>
Cc:     netdev@...r.kernel.org, davem@...emloft.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] macsec: Netlink support of XPN cipher suites (IEEE 802.1AEbw)

On Thu, Mar 5, 2020 at 5:24 PM Michal Kubecek <mkubecek@...e.cz> wrote:
> Yes, new attribute identifiers should always be added as last so that
> you don't change existing values.

Created a new patch: macsec: Backward compatibility bugfix of consts values

On Thu, Mar 5, 2020 at 5:24 PM Michal Kubecek <mkubecek@...e.cz> wrote:
>
> On Thu, Mar 05, 2020 at 11:53:29PM +0000, Era Mayflower wrote:
> > Do you think that inserting those new enum values after *_PAD would be
> > a good solution?
>
> Yes, new attribute identifiers should always be added as last so that
> you don't change existing values.
>
> Michal
>
> > On Thu, Mar 5, 2020 at 11:51 PM Era Mayflower <mayflowerera@...il.com> wrote:
> > >
> > > Do you think that inserting those new enum values after *_PAD would be a good solution?
> > >
> > > On Thu, Mar 5, 2020 at 2:02 PM Michal Kubecek <mkubecek@...e.cz> wrote:
> > >>
> > >> On Thu, Mar 05, 2020 at 10:01:08PM +0000, Era Mayflower wrote:
> > >> > Netlink support of extended packet number cipher suites,
> > >> > allows adding and updating XPN macsec interfaces.
> > >> >
> > >> > Added support in:
> > >> >     * Creating interfaces with GCM-AES-XPN-128 and GCM-AES-XPN-256.
> > >> >     * Setting and getting packet numbers with 64bit of SAs.
> > >> >     * Settings and getting ssci of SCs.
> > >> >     * Settings and getting salt of SecYs.
> > >> >
> > >> > Depends on: macsec: Support XPN frame handling - IEEE 802.1AEbw.
> > >> >
> > >> > Signed-off-by: Era Mayflower <mayflowerera@...il.com>
> > >> > ---
> > >> [...]
> > >> > diff --git a/include/net/macsec.h b/include/net/macsec.h
> > >> > index a0b1d0b5c..3c7914ff1 100644
> > >> > --- a/include/net/macsec.h
> > >> > +++ b/include/net/macsec.h
> > >> > @@ -11,6 +11,9 @@
> > >> >  #include <uapi/linux/if_link.h>
> > >> >  #include <uapi/linux/if_macsec.h>
> > >> >
> > >> > +#define MACSEC_DEFAULT_PN_LEN 4
> > >> > +#define MACSEC_XPN_PN_LEN 8
> > >> > +
> > >> >  #define MACSEC_SALT_LEN 12
> > >> >
> > >> >  typedef u64 __bitwise sci_t;
> > >> > diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
> > >> > index 024af2d1d..ee424d915 100644
> > >> > --- a/include/uapi/linux/if_link.h
> > >> > +++ b/include/uapi/linux/if_link.h
> > >> > @@ -462,6 +462,8 @@ enum {
> > >> >       IFLA_MACSEC_SCB,
> > >> >       IFLA_MACSEC_REPLAY_PROTECT,
> > >> >       IFLA_MACSEC_VALIDATION,
> > >> > +     IFLA_MACSEC_SSCI,
> > >> > +     IFLA_MACSEC_SALT,
> > >> >       IFLA_MACSEC_PAD,
> > >> >       __IFLA_MACSEC_MAX,
> > >> >  };
> > >>
> > >> Doesn't this break backword compatibility? You change the value of
> > >> IFLA_MACSEC_PAD; even if it's only used as padding, if an old client
> > >> uses it, new kernel will interpret it as IFLA_MACSEC_SSCI (an the same
> > >> holds for new client with old kernel).
> > >>
> > >> > diff --git a/include/uapi/linux/if_macsec.h b/include/uapi/linux/if_macsec.h
> > >> > index 1d63c43c3..c8fab9673 100644
> > >> > --- a/include/uapi/linux/if_macsec.h
> > >> > +++ b/include/uapi/linux/if_macsec.h
> > >> > @@ -25,6 +25,8 @@
> > >> >  /* cipher IDs as per IEEE802.1AEbn-2011 */
> > >> >  #define MACSEC_CIPHER_ID_GCM_AES_128 0x0080C20001000001ULL
> > >> >  #define MACSEC_CIPHER_ID_GCM_AES_256 0x0080C20001000002ULL
> > >> > +#define MACSEC_CIPHER_ID_GCM_AES_XPN_128 0x0080C20001000003ULL
> > >> > +#define MACSEC_CIPHER_ID_GCM_AES_XPN_256 0x0080C20001000004ULL
> > >> >
> > >> >  /* deprecated cipher ID for GCM-AES-128 */
> > >> >  #define MACSEC_DEFAULT_CIPHER_ID     0x0080020001000001ULL
> > >> > @@ -66,6 +68,8 @@ enum macsec_secy_attrs {
> > >> >       MACSEC_SECY_ATTR_INC_SCI,
> > >> >       MACSEC_SECY_ATTR_ES,
> > >> >       MACSEC_SECY_ATTR_SCB,
> > >> > +     MACSEC_SECY_ATTR_SSCI,
> > >> > +     MACSEC_SECY_ATTR_SALT,
> > >> >       MACSEC_SECY_ATTR_PAD,
> > >> >       __MACSEC_SECY_ATTR_END,
> > >> >       NUM_MACSEC_SECY_ATTR = __MACSEC_SECY_ATTR_END,
> > >> > @@ -78,6 +82,7 @@ enum macsec_rxsc_attrs {
> > >> >       MACSEC_RXSC_ATTR_ACTIVE,  /* config/dump, u8 0..1 */
> > >> >       MACSEC_RXSC_ATTR_SA_LIST, /* dump, nested */
> > >> >       MACSEC_RXSC_ATTR_STATS,   /* dump, nested, macsec_rxsc_stats_attr */
> > >> > +     MACSEC_RXSC_ATTR_SSCI,    /* config/dump, u32 */
> > >> >       MACSEC_RXSC_ATTR_PAD,
> > >> >       __MACSEC_RXSC_ATTR_END,
> > >> >       NUM_MACSEC_RXSC_ATTR = __MACSEC_RXSC_ATTR_END,
> > >>
> > >> The same problem with these two.
> > >>
> > >> I'm also a bit unsure about the change of type and length of
> > >> MACSEC_SA_ATTR_PN but I would have to get more familiar with the code to
> > >> see if it is really a problem.
> > >>
> > >> Michal