On Tue, Nov 27, 2018 at 5:58 PM Stephen Smalley <sds@xxxxxxxxxxxxx> wrote:
> On 11/27/18 5:36 AM, Ondrej Mosnacek wrote:
> > This patch is kept separate only for review. Eventually it will be
> > folded into the previous patch.
>
> This one triggers a lot of warnings (security_compute_av: unrecognized
> SID 0, security_sid_to_context_core: unrecognized SID 0) and some
> failures during selinux-testsuite inet_socket tests. While the policy
> doesn't provide an entry for SECSID_NULL, the sidtab search logic was
> remapping it to the unlabeled context and that was apparently being
> relied upon by the labeled networking code IIUC.
You're right, I made a mistake in the sidtab_search_core() function -
it shouldn't just return NULL when sid == 0, but instead skip to the
default-to-unlabeled fallback. This will be easy to fix.
Thanks for testing!
I wonder why I didn't get any inet_socket failures when running the
testsuite myself... I will have to look at it closer tomorrow.
>
>
> >
> > Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
> > ---
> > security/selinux/ss/policydb.c | 2 +-
> > security/selinux/ss/sidtab.c | 25 ++++++++++++++++---------
> > security/selinux/ss/sidtab.h | 3 ++-
> > 3 files changed, 19 insertions(+), 11 deletions(-)
> >
> > diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
> > index 59359fa0bd74..a50d625e7946 100644
> > --- a/security/selinux/ss/policydb.c
> > +++ b/security/selinux/ss/policydb.c
> > @@ -912,7 +912,7 @@ int policydb_load_isids(struct policydb *p, struct sidtab *s)
> > sidtab_destroy(s);
> > goto out;
> > }
> > - if (c->sid[0] > SECINITSID_NUM) {
> > + if (c->sid[0] == SECSID_NULL || c->sid[0] > SECINITSID_NUM) {
> > pr_err("SELinux: Initial SID %s out of range.\n",
> > c->u.name);
> > sidtab_destroy(s);
> > diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c
> > index fd8115b211a6..e157d8240cf1 100644
> > --- a/security/selinux/ss/sidtab.c
> > +++ b/security/selinux/ss/sidtab.c
> > @@ -23,7 +23,7 @@ int sidtab_init(struct sidtab *s)
> > if (!s->htable)
> > return -ENOMEM;
> >
> > - for (i = 0; i <= SECINITSID_NUM; i++)
> > + for (i = 0; i < SECINITSID_NUM; i++)
> > s->isids[i].set = 0;
> >
> > for (i = 0; i < SIDTAB_SIZE; i++)
> > @@ -86,8 +86,15 @@ static int sidtab_insert(struct sidtab *s, u32 sid, struct context *context)
> >
> > int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context)
> > {
> > - struct sidtab_isid_entry *entry = &s->isids[sid];
> > - int rc = context_cpy(&entry->context, context);
> > + struct sidtab_isid_entry *entry;
> > + int rc;
> > +
> > + if (sid == 0 || sid > SECINITSID_NUM)
> > + return -EINVAL;
> > +
> > + entry = &s->isids[sid - 1];
> > +
> > + rc = context_cpy(&entry->context, context);
> > if (rc)
> > return rc;
> >
> > @@ -116,19 +123,19 @@ static struct context *sidtab_search_core(struct sidtab *s, u32 sid, int force)
> > struct context *context;
> > struct sidtab_isid_entry *entry;
> >
> > - if (!s)
> > + if (!s || sid == 0)
> > return NULL;
> >
> > if (sid > SECINITSID_NUM) {
> > context = sidtab_lookup(s, sid - (SECINITSID_NUM + 1));
> > } else {
> > - entry = &s->isids[sid];
> > + entry = &s->isids[sid - 1];
> > context = entry->set ? &entry->context : NULL;
> > }
> > if (context && (!context->len || force))
> > return context;
> >
> > - entry = &s->isids[SECINITSID_UNLABELED];
> > + entry = &s->isids[SECINITSID_UNLABELED - 1];
> > return entry->set ? &entry->context : NULL;
> > }
> >
> > @@ -283,11 +290,11 @@ int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid)
> > int rc;
> > u32 i;
> >
> > - for (i = 0; i <= SECINITSID_NUM; i++) {
> > + for (i = 0; i < SECINITSID_NUM; i++) {
> > struct sidtab_isid_entry *entry = &s->isids[i];
> >
> > if (entry->set && context_cmp(context, &entry->context)) {
> > - *sid = i;
> > + *sid = i + 1;
> > return 0;
> > }
> > }
> > @@ -334,7 +341,7 @@ void sidtab_destroy(struct sidtab *s)
> > if (!s)
> > return;
> >
> > - for (i = 0; i <= SECINITSID_NUM; i++)
> > + for (i = 0; i < SECINITSID_NUM; i++)
> > if (s->isids[i].set)
> > context_destroy(&s->isids[i].context);
> >
> > diff --git a/security/selinux/ss/sidtab.h b/security/selinux/ss/sidtab.h
> > index dc0a80bc8894..e657ae6bf996 100644
> > --- a/security/selinux/ss/sidtab.h
> > +++ b/security/selinux/ss/sidtab.h
> > @@ -36,7 +36,8 @@ struct sidtab {
> > struct sidtab_node *cache[SIDTAB_CACHE_LEN];
> > spinlock_t lock;
> >
> > - struct sidtab_isid_entry isids[SECINITSID_NUM + 1];
> > + /* index == SID - 1 (no entry for SECSID_NULL) */
> > + struct sidtab_isid_entry isids[SECINITSID_NUM];
> > };
> >
> > int sidtab_init(struct sidtab *s);
> >
>
--
Ondrej Mosnacek <omosnace at redhat dot com>
Associate Software Engineer, Security Technologies
Red Hat, Inc.
