apparmor/parser/tst
John Johansen a6691ca53e Merge parser: fix Normalizatin infinite loop
Expression simplification can get into an infinite loop due to eps
pairs hiding behind and alternation that can't be caught by
normalize_eps() (which exists in the first place to stop a similar
loop).

The loop in question happens in AltNode::normalize when a subtree has
the following structure.

1. elseif (child[dir]->is_type(ALT_NODE)) rotate_node too

                   alt
                   /\
                  /  \
                 /    \
               eps    alt
                      /\
                     /  \
                    /    \
                  alt    eps
                  /\
                 /  \
                /    \
               eps   eps

2. if (normalize_eps(dir)) results in

                   alt
                   /\
                  /  \
                 /    \
               alt    eps
               /\
              /  \
             /    \
           alt    eps
           /\
          /  \
         /    \
       eps   eps

3. elseif (child[dir]->is_type(ALT_NODE)) rotate_node too

                   alt
                   /\
                  /  \
                 /    \
               alt    alt
              /\        /\
             /  \      /  \
            /    \    /    \
          eps    eps eps   eps

4. elseif (child[dir]->is_type(ALT_NODE)) rotate_node too

                   alt
                   /\
                  /  \
                 /    \
               eps    alt
                      /\
                     /  \
                    /    \
                  eps    alt
                         /\
                        /  \
                       /    \
                     eps   eps

5. if (normalize_eps(dir)) results in

                  alt
                   /\
                  /  \
                 /    \
                alt   eps
                /\
               /  \
              /    \
            eps    alt
                    /\
                   /  \
                  /    \
                 eps   eps

6. elseif (child[dir]->is_type(ALT_NODE)) rotate_node too

                  alt
                   /\
                  /  \
                 /    \
                eps   alt
                       /\
                      /  \
                     /    \
                    alt  eps
                    /\
                   /  \
                  /    \
                eps   eps

back to beginning of cycle

Fix this by detecting the creation of an eps_pair in rotate_node(),
that pair can be immediately eliminated by simplifying the tree in that
step.

In the above cycle the pair creation is caught at step 3 resulting
in

3. elseif (child[dir]->is_type(ALT_NODE)) rotate_node too

                   alt
                   /\
                  /  \
                 /    \
               alt    eps
               /\
              /  \
             /    \
           eps    eps

4.  elseif (child[dir]->is_type(ALT_NODE)) rotate_node too

                   alt
                   /\
                  /  \
                 /    \
               eps   alt
                      /\
                     /  \
                    /    \
                  eps    eps

which gets reduced to

                   alt
                   /\
                  /  \
                 /    \
               eps   eps

breaking the normalization loop. The degenerate alt node will be caught
in turn when its parent is dealt with.

This needs to be backported to all releases

Closes: https://gitlab.com/apparmor/apparmor/-/issues/398
Fixes: 846cee506 ("Split out parsing and expression trees from regexp.y")
Reported-by: Christian Boltz <apparmor@cboltz.de>
Signed-off-by: John Johansen <john.johansen@canonical.com>

Closes #398
MR: https://gitlab.com/apparmor/apparmor/-/merge_requests/1252
Approved-by: Georgia Garcia <georgia.garcia@canonical.com>
Merged-by: John Johansen <john@jjmx.net>
2024-06-14 19:39:21 +00:00
..
dirtest dirtest.sh: don't rely on apparmor_parser -N's output sort order to be deterministic 2022-07-25 10:14:31 +00:00
errors parser error tests: add filename profile deprecation checks 2020-05-05 02:16:23 -07:00
features_files parser: Update features.all file for new kernel features 2016-03-19 03:03:18 -05:00
simple_tests Merge parser: fix Normalizatin infinite loop 2024-06-14 19:39:21 +00:00
caching.profile actually add caching tests 2009-11-11 11:07:50 -08:00
caching.py Change string formatting method in Python tests 2023-02-19 16:54:38 -05:00
dirtest.sh dirtest.sh: don't rely on apparmor_parser -N's output sort order to be deterministic 2022-07-25 10:14:31 +00:00
equality.sh parser: make lead # in assignment value indicate a comment 2024-06-08 01:32:22 -07:00
errors.py parser/errors.py: convert to unittest.main() 2023-07-13 13:40:42 -05:00
gen-dbus.py Change string formatting method in Python tests 2023-02-19 16:54:38 -05:00
gen-xtrans.py Add missing comma to tuple 2023-02-19 17:13:15 -05:00
Makefile libapparmor: fix handling of failed symlink traversal 2022-02-27 00:55:41 -08:00
minimize.sh treewide: spelling/typo fixes in comments and docs 2020-12-01 12:47:11 -08:00
mk_features_file.py Change string formatting method in Python tests 2023-02-19 16:54:38 -05:00
parser.conf parser: add empty config file for parser caching tests 2018-08-21 23:14:52 -07:00
README treewide: spelling/typo fixes in comments and docs 2020-12-01 12:47:11 -08:00
simple.pl error out on superfluous TODOs 2018-11-06 21:44:40 +01:00
testlib.py Change string formatting method in Python tests 2023-02-19 16:54:38 -05:00
uservars.conf as ACKed on IRC, drop the unused $Id$ tags everywhere 2010-12-20 12:29:10 -08:00
valgrind_simple.py Change string formatting method in Python tests 2023-02-19 16:54:38 -05:00

This is the README for the AppArmor parser regression testsuite.

Running the testsuite
---------------------
Running the tests is pretty easy, a simple 'make tests' should make it
go, assuming the subdomain parser and perl are installed.

There is a user configuration file 'uservars.conf'. If you wish to test
against a different parser, or use a different set of profiles for the
simple.pl test, you can change those settings in 'uservars.conf'.

You can also override which parser is used through make by specifying
the PARSER variable. For example, to run the tests on the system parser,
run 'make PARSER=/sbin/apparmor_parser'.

Adding to the testsuite
-----------------------

The testsuite currently contains one testscript (simple.pl) and makes use
of perl's Test::Simple, Test::Harness, and prove utilities (see 'perldoc
Test::Tutorial', 'perldoc Test::Simple', 'perldoc Test::Harness', and
'man 1 prove' for more information on these).

It should be relatively easy to extend the suite with other testscripts,
as long as they're written using Test::Simple or can emulate the
Test::Harness protocol. To add a script, add it to the TESTS variable
in the Makefile, and it will included in the tests to be run.

However, in many cases, it is not necessary to add an entire new
testscript for a testcase. Instead, the simple testcase (see below)
will run all the profiles it finds on the parser, thus adding testcases
is usually as simple as writing a new profile with a couple of extra
comments.

Simple parsing tests (simple.pl)
--------------------------------
This test script tests the parser front end's ability to identify legal
profiles. It does this by running the parser against several legal and
illegal profiles (in debug mode, so as not to load them into the module
proper)

The simple script has the parser attempt to parse all of the profiles
named *.sd in the simple_tests/ subdirectory; thus, to add a new profile
to test, simply add it to the simple_tests/ directory. The simple
script also adds the testdir (simple_tests/ by default) to the parsers
include path (assuming that particular bug has been fixed :-)). There
is an includes/ subdir to place additional includes if necessary (we
purposefully choose to use different directory names versus the shipped
profiles to minimize testsuite breakage with changes in the external
policy).

The simple script looks for a few special comments in the profile,
#=DESCRIPTION, #=EXRESULT, and #=TODO:

  - #=DESCRIPTION -- all text following the keyword is considered a
    description for the test. Please try to make these meaningful.

  - #=EXRESULT -- This records the expected result of parsing this
    profile. Values can either be PASS or FAIL; if no comment is found
    that matches this pattern, then the profile is assumed to have an
    expected parse result of PASS.

  - #=TODO -- marks the test as being for a future item to implement and
    thus are expected testsuite failures and should be ignored.

  - #=DISABLED -- skips the test, and marks it as a failed TODO task.
    Useful if the particular testcase causes the parser to infinite
    loop or dump core.

Otherwise, the profile is passed on as-is to the subdomain parser.