selinux/libsepol
James Carter 9d8fd6e9b9 libsepol: Further improve binary policy optimization
This improves commit b8213acf (libsepol: add a function to optimize
kernel policy) by Ondrej Mosnacek <omosnace@redhat.com> by always
removing redundant conditional rules which have an identical rule
in the unconditional policy.

Add a flag called not_cond to is_avrule_redundant(). When checking
unconditional rules against the avtab (which stores the unconditional
rules) we need to skip the actual rule that we are checking (otherwise
a rule would be determined to be redundant with itself and bad things
would happen), but when checking a conditional rule against the avtab
we do not want to skip an identical rule (which is what currently
happens), we want to remove the redundant permissions in the conditional
rule.

A couple of examples to illustrate when redundant condtional rules
are not removed.

Example 1
  allow t1 t2:class1 perm1;
  if (bool1) {
    allow t1 t2:class1 perm1;
  }
The conditional rule is clearly redundant, but without this change it
will not be removed, because of the check for an identical rule.

Example 2
  typeattribute t1 a1;
  allow t1 t2:class1 perm1;
  allow a1 t2:class1 perm1;
  if (bool1) {
    allow t1 t2:class1 perm1;
  }
The conditional rule is again clearly redundant, but now the order of
processing during the optimization will determine whether or not the
rule is removed. Because a1 contains only t1, a1 and t1 are considered
to be supersets of each other. If the rule with the attribute is
processed first, then it will be determined to be redundant and
removed, so the conditional rule will not be removed. But if the rule
with the type is processed first, then it will be removed and the
conditional rule will be determined to be redundant with the rule with
the attribute and removed as well.

The change reduces the size of policy a bit more than the original
optimization. Looking at the change in number of allow rules, there is
about a 10% improvement over the old optimization.
           orig    old    new
Refpolicy 113284  82467  78053
Fedora    106410  64015  60008

Signed-off-by: James Carter <jwcart2@tycho.nsa.gov>
2019-09-30 15:13:17 -04:00
..
cil Fix many misspellings 2019-09-18 22:47:35 +02:00
include Fix many misspellings 2019-09-18 22:47:35 +02:00
man selinux: Update manpages after removing legacy boolean and user code 2019-07-29 23:46:47 +02:00
src libsepol: Further improve binary policy optimization 2019-09-30 15:13:17 -04:00
tests libsepol, libsemanage: add a macro to silence static analyzer warnings in tests 2019-09-30 08:43:41 -04:00
utils libsepol: build: follow standard semantics for DESTDIR and PREFIX 2018-02-14 15:59:36 +01:00
.gitignore
COPYING
Makefile
VERSION Update VERSIONs to 2.9 for release. 2019-03-15 11:32:30 +01:00