Teach audit2why to recognize type bounds failures. This required
updating libsepol sepol_compute_av_reason() to identify bounds
failures, and updating libsepol context_struct_compute_av() to
include the type bounds logic from the kernel.
This could potentially be further augmented to provide more detailed
reporting via the reason buffer to include information similar to
what security_dump_masked_av() reports in the kernel. However, it
is unclear if this is needed. It is already possible to get type
bounds checking at policy build time by enabling expand-check=1
in /etc/selinux/semanage.conf (or by default when compiling
monolithic policy).
Before:
type=AVC msg=audit(1480451925.038:3225): avc: denied { getattr } for pid=7118 comm="chmod" path="/home/sds/selinux-testsuite/tests/bounds/bounds_file_blue" dev="dm-2" ino=23337697 scontext=unconfined_u:unconfined_r:test_bounds_child_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:test_bounds_file_blue_t:s0 tclass=file permissive=0
Was caused by:
Unknown - would be allowed by active policy
Possible mismatch between this policy and the one under which the audit message was generated.
Possible mismatch between current in-memory boolean settings vs. permanent ones.
After:
type=AVC msg=audit(1480451925.038:3225): avc: denied { getattr } for pid=7118 comm="chmod" path="/home/sds/selinux-testsuite/tests/bounds/bounds_file_blue" dev="dm-2" ino=23337697 scontext=unconfined_u:unconfined_r:test_bounds_child_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:test_bounds_file_blue_t:s0 tclass=file permissive=0
Was caused by:
Typebounds violation.
Add an allow rule for the parent type.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
