On Mon, Aug 26, 2019 at 10:20 AM Joshua Brindle
<joshua.brindle@xxxxxxxxxxxxxxx> wrote:
> A policy developer can now specify glblub as a default_range default and
> the computed transition will be the intersection of the mls range of
> the two contexts.
>
> Signed-off-by: Joshua Brindle <joshua.brindle@xxxxxxxxxxxxxxx>
> ---
> security/selinux/include/security.h | 3 ++-
> security/selinux/ss/context.h | 6 ++++++
> security/selinux/ss/ebitmap.c | 15 +++++++++++++++
> security/selinux/ss/ebitmap.h | 1 +
> security/selinux/ss/mls.c | 2 ++
> security/selinux/ss/mls_types.h | 28 ++++++++++++++++++++++++++++
> security/selinux/ss/policydb.c | 5 +++++
> security/selinux/ss/policydb.h | 1 +
> 8 files changed, 60 insertions(+), 1 deletion(-)
Independent from the comments below I think we need to additional
things for this patch:
* A much better description. At the very least I would like you to
explain the MLS bounding and how one might use this (think sample
code); and don't worry about your description being too long ;)
* Tests (see the selinux-testsuite).
> diff --git a/security/selinux/ss/context.h b/security/selinux/ss/context.h
> index 2260c44a568c..cecb84d8b26c 100644
> --- a/security/selinux/ss/context.h
> +++ b/security/selinux/ss/context.h
> @@ -95,6 +95,12 @@ static inline int mls_context_cpy_high(struct context *dst, struct context *src)
> return rc;
> }
>
> +
> +static inline int mls_context_glblub(struct context *dst, struct context *c1, struct context *c2)
> +{
> + return mls_range_glblub(&dst->range, &c1->range, &c2->range);
> +}
Considering the other functions that are already defined in context.h,
it seems like you could get rid of mls_range_glblub() and put the guts
in mls_context_glblub(), yes? Unless I missed something
mls_range_glblub() is only ever called from mls_context_glblub() which
makes one of these functions pointless.
> static inline int mls_context_cmp(struct context *c1, struct context *c2)
> {
> return ((c1->range.level[0].sens == c2->range.level[0].sens) &&
> diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
> index 09929fc5ab47..2042729b81f8 100644
> --- a/security/selinux/ss/ebitmap.c
> +++ b/security/selinux/ss/ebitmap.c
> @@ -77,6 +77,21 @@ int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src)
> return 0;
> }
>
> +int ebitmap_and(struct ebitmap *dst, struct ebitmap *e1, struct ebitmap *e2)
> +{
> + unsigned int i, length = min(ebitmap_length(e1), ebitmap_length(e2));
A line of vertical whitespace here would be nice.
> + ebitmap_init(dst);
> + for (i=0; i < length; i++) {
> + if (ebitmap_get_bit(e1, i) && ebitmap_get_bit(e2, i)) {
> + int rc = ebitmap_set_bit(dst, i, 1);
> + if (rc < 0)
> + return rc;
> + }
> + }
Same as above, a line of vertical whitespace would be nice.
Beyond that, since this is an AND operation, could we make better use
of things like find_first_bit()/ebitmap_start_positive()/ebitmap_next_positive()
to skip along one of the bitmaps instead of needing to call
ebitmap_get_bit() for each bit? I imagine it would be quicker that
way.
> + return 0;
> +}
...
> diff --git a/security/selinux/ss/mls_types.h b/security/selinux/ss/mls_types.h
> index 068e0d7809db..e2a20eb0e87c 100644
> --- a/security/selinux/ss/mls_types.h
> +++ b/security/selinux/ss/mls_types.h
> @@ -39,6 +39,34 @@ static inline int mls_level_dom(struct mls_level *l1, struct mls_level *l2)
> ebitmap_contains(&l1->cat, &l2->cat, 0));
> }
>
> +static inline int mls_range_glblub(struct mls_range *dst, struct mls_range *r1, struct mls_range *r2)
> +{
> + int rc = 0;
> +
> + if (r1->level[1].sens < r2->level[0].sens || r2->level[1].sens < r1->level[0].sens) {
> + {
These braces aren't necessary, take them from the patch and give them
to a child in need.
> + // These ranges have no common sensitivities
Please use the old C style comments instead of the C++ style comments
(this applies to the whole patch). I know you don't track kernel
development very closely, but we just had a discussion about this
on-list earlier this summer.
> + return -1;
> + }
> +
> + // Take the greatest of the low
> + dst->level[0].sens = max(r1->level[0].sens, r2->level[0].sens);
> +
> + // Take the least of the high
> + dst->level[1].sens = min(r1->level[1].sens, r2->level[1].sens);
> +
> + rc = ebitmap_and(&dst->level[0].cat, &r1->level[0].cat, &r2->level[0].cat);
> + if (rc)
> + goto out;
> +
> + rc = ebitmap_and(&dst->level[1].cat, &r1->level[1].cat, &r2->level[1].cat);
> + if (rc)
> + goto out;
> +
> +out:
> + return rc;
> +}
--
paul moore
www.paul-moore.com
