* Properly support syscalls in filter conditions
Syscalls have their own numbers but they weren't really handled within
falco. This meant that there wasn't a way to handle filters with
evt.type=xxx clauses where xxx was a value that didn't have a
corresponding event entry (like "madvise", for examples), or where a
syscall like open could also be done indirectly via syscall(__NR_open,
...).
First, add a new top-level global syscalls that maps from a string like
"madvise" to all the syscall nums for that id, just as we do for event
names/numbers.
In the compiler, when traversing the AST for evt.type=XXX or evt.type in
(XXX, ...) clauses, also try to match XXX against the global syscalls
table, and return any ids in a standalone table.
Also throw an error if an XXX doesn't match any event name or syscall name.
The syscall numbers are passed as an argument to sinsp_evttype_filter so
it can preindex the filters by syscall number.
This depends on https://github.com/draios/sysdig/pull/1100
* Add unit test for syscall support
This does a madvise, which doesn't have a ppm event type, both directly
and indirectly via syscall(__NR_madvise, ...), as well as an open
directly + indirectly. The corresponding rules file matches on madvise
and open.
The test ensures that both opens and both madvises are detected.
* Add ability to read rules files from directories
When the argument to -r <path> or an entry in falco.yaml's rules_file
list is a directory, read all files in the directory and add them to the
rules file list. The files in the directory are sorted alphabetically
before being added to the list.
The installed falco adds directories /etc/falco/rules.available and
/etc/falco/rules.d and moves /etc/falco/application_rules.yaml to
/etc/falco/rules.available. /etc/falco/rules.d is empty, but the idea is
that admins can symlink to /etc/falco/rules.available for applications
they want to enable.
This will make it easier to add application-specific rulesets that
admins can opt-in to.
* Unit test for reading rules from directory
Copy the rules/trace file from the test multiple_rules to a new test
rules_directory. The rules files are in rules/rules_dir/{000,001}*.yaml,
and the test uses a rules_file argument of rules_dir. Ensure that the
same events are detected.
* Allow appending to skipped rules
If a rule has an append attribute but the original rule was skipped (due
to having lower priority than the configured priority), silently skip
the appending rule instead of returning an error.
* Unit test for appending to skipped rules
Unit test verifies fix for appending to skipped rules. One rules file
defines a rule with priority WARNING, a second rules file appends to
that rules file, and the configured priority is ERROR.
Ensures that falco rules without errors.
Add the ability to append to rules/macros, like we already do with
lists. For rules/macros, if the object has an append: true key, the
condition value is appended to the condition of an existing rule/macro
with the same name.
Like lists, it's an error to specify append: true without there being an
existing rule/macro.
Also add tests that test the same kind of things we did for lists:
- That append: true really does append
- That append: false overwrites the rule/macro
- That it's an error to append with a prior rule/macro existing.
Add new unit tests to check that list substitution is working as
expected, with test cases for the list substitution occurring at the
beginning, middle, and end of a condition.
Also add tests that verify that overrides on list/macro/rule names
always occur in order.
Add automated tests that verify the ability to tag sets of rules,
disable them with -T, and run them with -t, works:
- New test option disable_tags adds -T <tag> arguments to the falco
command line, and run_tags adds -t <tag> arguments to the falco command
line.
- A new trace file open-multiple-files.scap opens 13 different files,
and a new rules file has 13 different rules with all combinations of
the tags a, b, c (both forward and backward), a rule with an empty
list of tags, a rule with no tags field, and a rule with a completely
different tag d.
Using the above, add tests for:
- Both disabling all combations of a, b, c using disable_tags as well as
run all combinations of a, b, c, using run_tags.
- Specifying both disabled (-T/-D) and enabled (-t) rules. Not allowed.
- Specifying a ruleset while having tagged rules enabled, rules based
on a name disabled, and no particular rules enabled or disabled.
Add a test that specifically tests truncated outputs. A rule contains an
output field %fd.cport which has no value for an open event. Ensure that
the rule's output has <NA> for the cport and the remainder of the rule's
output is filled in.
New tests that test every possible override:
- Overriding a rule with one that doesn't match
- Overriding a macro to one that doesn't match
- Overriding a top level list to a binary that doesn't match
- Overriding an embedded list to one that doesn't match
In each case, the override results in no longer matching an open by the
program "cat".
Add the ability to check falco's return code with exit_status and to
generally match stderr with stderr_contains in a test.
Use those to create a test that has an invalid output expression using
%not_a_real_field. It expects falco to exit with 1 and the output to
contain a message about the invalid output.
Add test that cover reading from multiple sets of rule files and
disabling rules. Specific changes:
- Modify falco to allow multiple -r arguments to read from multiple
files.
- In the test multiplex file, add a disabled_rules attribute,
containing a sequence of rules to disable. Result in -D arguments
when running falco.
- In the test multiplex file, 'rules_file' can be a sequence. It
results in multiple -r arguments when running falco.
- In the test multiplex file, 'detect_level' can be a squence of
multiple severity levels. All levels will be checked for in the
output.
- Move all test rules files to a rules subdirectory and all trace files
to a traces subdirectory.
- Add a small trace file for a simple cat of /dev/null. Used by the
new tests.
- Add the following new tests:
- Reading from multiple files, with the first file being
empty. Ensure that the rules from the second file are properly
loaded.
- Reading from multiple files with the last being empty. Ensures
that the empty file doesn't overwrite anything from the first
file.
- Reading from multiple files with varying severity levels for each
rule. Ensures that both files are properly read.
- Disabling rules from a rules file, both with full rule names
and regexes. Will result in not detecting anything.
