On Wed, Oct 17, 2018 at 6:07 PM William Roberts
<bill.c.roberts@xxxxxxxxx> wrote:
> On Wed, Oct 17, 2018 at 7:48 AM Ondrej Mosnacek <omosnace@xxxxxxxxxx> wrote:
> >
> > We need to convert from little-endian before dong range checks on the
> > ibpkey port numbers, otherwise we would be checking a wrong value.
> >
> > Fixes: 9fbb3112769a ("libsepol: Add ibpkey ocontext handling")
> > Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
> > ---
> > libsepol/src/policydb.c | 14 ++++++++++----
> > 1 file changed, 10 insertions(+), 4 deletions(-)
> >
> > diff --git a/libsepol/src/policydb.c b/libsepol/src/policydb.c
> > index a6d76ca3..dc201e2f 100644
> > --- a/libsepol/src/policydb.c
> > +++ b/libsepol/src/policydb.c
> > @@ -2830,15 +2830,21 @@ static int ocontext_read_selinux(struct policydb_compat_info *info,
> > break;
> > case OCON_IBPKEY:
> > rc = next_entry(buf, fp, sizeof(uint32_t) * 4);
> > - if (rc < 0 || buf[2] > 0xffff || buf[3] > 0xffff)
> > + if (rc < 0)
> > return -1;
> >
> > + c->u.ibpkey.low_pkey = le32_to_cpu(buf[2]);
> > + c->u.ibpkey.high_pkey = le32_to_cpu(buf[3]);
>
> Ahh you're assigning a 32 bit value to a 16 bit variable low|high_pkey. I think
> you need to assign them to a uint32_t if you want to actually range check them.
Oh right, I didn't realize those fields are 16-bit... Let me fix it and re-spin.
>
> > +
> > + if (c->u.ibpkey.low_pkey > 0xffff ||
> > + c->u.ibpkey.high_pkey > 0xffff)
> > + return -1;
> > +
> > + /* we want c->u.ibpkey.subnet_prefix in network
> > + * (big-endian) order, just memcpy it */
> > memcpy(&c->u.ibpkey.subnet_prefix, buf,
> > sizeof(c->u.ibpkey.subnet_prefix));
> >
> > - c->u.ibpkey.low_pkey = le32_to_cpu(buf[2]);
> > - c->u.ibpkey.high_pkey = le32_to_cpu(buf[3]);
> > -
> > if (context_read_and_validate
> > (&c->context[0], p, fp))
> > return -1;
> > --
> > 2.17.2
> >
> See job: https://travis-ci.org/SELinuxProject/selinux/jobs/442750208
>
> Build fail with gcc:
>
> policydb.c:2839:31: error: comparison is always false due to limited
> range of data type [-Werror=type-limits]
> if (c->u.ibpkey.low_pkey > 0xffff ||
> ^
> policydb.c:2840:31: error: comparison is always false due to limited
> range of data type [-Werror=type-limits]
> c->u.ibpkey.high_pkey > 0xffff)
--
Ondrej Mosnacek <omosnace at redhat dot com>
Associate Software Engineer, Security Technologies
Red Hat, Inc.
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