[PATCH v20 18/23] NET: Store LSM netlabel data in a lsmblob
Paul Moore
paul at paul-moore.com
Sun Sep 6 03:27:50 UTC 2020
On Wed, Aug 26, 2020 at 11:21 AM Casey Schaufler <casey at schaufler-ca.com> wrote:
>
> Netlabel uses LSM interfaces requiring an lsmblob and
> the internal storage is used to pass information between
> these interfaces, so change the internal data from a secid
> to a lsmblob. Update the netlabel interfaces and their
> callers to accommodate the change. This requires that the
> modules using netlabel use the lsm_id.slot to access the
> correct secid when using netlabel.
>
> Reviewed-by: Kees Cook <keescook at chromium.org>
> Reviewed-by: John Johansen <john.johansen at canonical.com>
> Acked-by: Stephen Smalley <sds at tycho.nsa.gov>
> Signed-off-by: Casey Schaufler <casey at schaufler-ca.com>
> Cc: netdev at vger.kernel.org
> ---
> include/net/netlabel.h | 8 +--
> net/ipv4/cipso_ipv4.c | 27 ++++++----
> net/netlabel/netlabel_kapi.c | 6 +--
> net/netlabel/netlabel_unlabeled.c | 79 +++++++++--------------------
> net/netlabel/netlabel_unlabeled.h | 2 +-
> security/selinux/hooks.c | 2 +-
> security/selinux/include/security.h | 1 +
> security/selinux/netlabel.c | 2 +-
> security/selinux/ss/services.c | 4 +-
> security/smack/smack.h | 1 +
> security/smack/smack_lsm.c | 5 +-
> security/smack/smackfs.c | 10 ++--
> 12 files changed, 65 insertions(+), 82 deletions(-)
Minor change suggested to a comment below, but looks good otherwise.
Acked-by: Paul Moore <paul at paul-moore.com>
> diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
> index 2eb71579f4d2..8182b923e802 100644
> --- a/net/ipv4/cipso_ipv4.c
> +++ b/net/ipv4/cipso_ipv4.c
> @@ -106,15 +106,17 @@ int cipso_v4_rbm_strictvalid = 1;
> /* Base length of the local tag (non-standard tag).
> * Tag definition (may change between kernel versions)
> *
> - * 0 8 16 24 32
> - * +----------+----------+----------+----------+
> - * | 10000000 | 00000110 | 32-bit secid value |
> - * +----------+----------+----------+----------+
> - * | in (host byte order)|
> - * +----------+----------+
> - *
> + * 0 8 16 16 + sizeof(struct lsmblob)
> + * +----------+----------+---------------------+
> + * | 10000000 | 00000110 | LSM blob data |
> + * +----------+----------+---------------------+
> + *
> + * All secid and flag fields are in host byte order.
> + * The lsmblob structure size varies depending on which
> + * Linux security modules are built in the kernel.
> + * The data is opaque.
> */
> -#define CIPSO_V4_TAG_LOC_BLEN 6
> +#define CIPSO_V4_TAG_LOC_BLEN (2 + sizeof(struct lsmblob))
>
> /*
> * Helper Functions
> @@ -1469,7 +1471,12 @@ static int cipso_v4_gentag_loc(const struct cipso_v4_doi *doi_def,
>
> buffer[0] = CIPSO_V4_TAG_LOCAL;
> buffer[1] = CIPSO_V4_TAG_LOC_BLEN;
> - *(u32 *)&buffer[2] = secattr->attr.secid;
> + /* Ensure that there is sufficient space in the CIPSO header
> + * for the LSM data. This should never become an issue.
> + * The check is made from an abundance of caution. */
> + BUILD_BUG_ON(CIPSO_V4_TAG_LOC_BLEN > CIPSO_V4_OPT_LEN_MAX);
I like the BUILD_BUG_ON() check, but for reasons very similar to the
unix_skb_params changes I don't really like the "should never become
an issue" commentary. Granted, it is unlikely, but I don't think it
is wise to thumb our nose at fate.
> + memcpy(&buffer[2], &secattr->attr.lsmblob,
> + sizeof(secattr->attr.lsmblob));
>
> return CIPSO_V4_TAG_LOC_BLEN;
> }
--
paul moore
www.paul-moore.com
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