Also, print out the time of the last processed event in the output
fields of the notification.
Signed-off-by: Leonardo Di Donato <leodidonato@gmail.com>
Falco uses a shared buffer between the kernel and userspace to receive
the events (eg., system call information) in userspace.
Anyways, the underlying libraries can also timeout for various reasons.
For example, there could have been issues while reading an event.
Or the particular event needs to be skipped.
Normally, it's very unlikely that Falco does not receive events consecutively.
Falco is able to detect such uncommon situation.
Here you can configure the maximum number of consecutive timeouts without an event
after which you want Falco to alert.
By default this value is set to 1000 consecutive timeouts without an event at all.
Signed-off-by: Leonardo Di Donato <leodidonato@gmail.com>
The rationale is that in case Falco obtains a consistent number of
consecutive timeouts (in a row) without a valid event, something is
going wrong.
This because, normally, the libs send timeouts to Falco (also) to signal events to discard.
In such cases, which are the majority of cases, `ev` exists and is not
`null`.
Signed-off-by: Leonardo Di Donato <leodidonato@gmail.com>
This fix has two major points in it:
- when `std::stoll` is used in parse_as_int64 handle all the exceptions it
can throw (https://en.cppreference.com/w/cpp/string/basic_string/stol)
- when `process_k8s_audit_event` an eventual exception in it does not
stop the webserver process. This is done by doing a catch all handle
outside it and by logging an error message to the caller as well as in
stderr
Signed-off-by: Lorenzo Fontana <lo@linux.com>
In some cases, it might be useful to know what falco engine version a
given falco binary supports. We already have a --support option that
prints info about the system, config, rules files, etc.
Add a engine_info object, with an engine_version property containing the
falco engine version in falco_engine_version.h. In the output, it looks
like this:
...
"engine_info": {
"engine_version": 8
},
...
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
We want users to continue using rules without having to use exceptions.
Exceptions are an additional feature for more advanced use-cases, having
a warning in there will mean that everyone now adds an empty exception
to avoid the warning.
Co-Authored-By: Leonardo Grasso <me@leonardograsso.com>
Signed-off-by: Lorenzo Fontana <lo@linux.com>
While testing, I found a case when creating a pod where:
1) the first container had no securityContext value
2) the second container had a security context with privileged=true
and this did not match the default rule Create Privileged Pod, when it
should match.
The rule Create Privileged Pod uses the field
ka.req.pod.containers.privileged, which in turn uses
json_event_filter_check::def_extract(). def_extract() iterates
over a set of json_pointers, potentially expanding arrays as they are
returned. Many k8s audit fields use this extract function.
For ka.req.pod.containers.privileged, the first json_pointer is
/requestObject/spec/containers to find the list of containers, and the
second is /securityContext/privileged to extract the privileged property
out of the securityContext object. What's returned is an array of
true/false noting if each container is privileged.
The problem is that def_extract() aborts when iterating over arrays if
extracting a pointer from an array can't be done.
In this case, the first pointer extracts the array of containers, and
then when iterating over the array of containers, the security context
pointer doesn't extract, causing the whole filter field to abort and
return ::no_value.
The fix is to not abort when iterating over arrays, but use ::no_value
for that array item's value instead. This allows def_extract() to
extract the privileged value out of the second container.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Falco won't properly parse a rule like this:
---
- rule: Some Rule
desc: Some Desc
condition: evt.type=execve and container.image.repository = 271931939120.dkr
output: Some output
priority: INFO
---
This is the error when validating the rules:
Tue Mar 30 12:00:40 2021: Validating rules file(s):
Tue Mar 30 12:00:40 2021: /home/mstemm/test.yaml
1 errors:
Compilation error when compiling "evt.type=execve and container.image.repository = 271931939120.dkr": 63: syntax error, unexpected 'dkr', expecting 'or', 'and'
The parsing of the string on the right hand side stops at the period
before the dkr. The dkr then doesn't match the grammar, resulting in the
error.
Looking at the parser implementation more closely, the problem is in the
definition of "Number":
---
- Number = C(V "Hex" + V "Float" + V "Int") / function(n)
return tonumber(n)
end,
---
Note that it stops after the number, but does not have any requirement
about what follows.
This changes the definition of number to require that what follows the
number is not an identifier character. With this change, values that are
only numbers are parsed as numbers, and values that start with numbers
don't match the Number definition and are parsed as BareStrings instead.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
When returning a rule_result struct, also include a set of field names
used by all exceptions for this rule. This may make building exception
values a bit easier.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
If a list:
- list: foo
items: [a, b, c]
Was referenced in another list:
- list: bar
items: [foo, d, e, f]
The first list would not be marked as used, when it should.
This avoids mistaken messages like "list xxx not refered to by any rule/macro/list"
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Support exceptions properties on rules as described in
https://github.com/falcosecurity/falco/pull/1376.
- When parsing rules, add an empty exceptions table if not specified.
- If exceptions are specified, they must contain names and lists of
fields, and optionally can contain lists of comps and lists of lists of
values.
- If comps are not specified, = is used.
- If a rule has exceptions and append:true, add values to the original rule's
exception values with the matching name.
- It's a warning but not an error to have exception values with a name
not matching any fields.
After loading all rules, build the exception condition string based on
any exceptions:
- If an exception has a single value for the "fields" property, values are
combined into a single set to build a condition string like "field
cmp (val1, val2, ...)".
- Otherwise, iterate through each rule's exception
values, finding the matching field names (field1, field2, ...) and
comp operators (cmp1, cmp2, ...), then
iterating over the list of field values (val1a, val1b, ...), (val2a,
val2b, ...), building up a string of the form:
and not ((field1 cmp1 val1a and field2 cmp2 val1b and ...) or
(field1 cmp1 val2a and field2 cmp2 val2b and ...)...
)"
- If a value is not already quoted and contains a space, quote it in the
string.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
When parsing a rules file, if a top level object is not one of the known
types rule, macro, list, required_engine_version, instead of failing
parsing, add a warning instead.
This adds some forwards-compatibility to rules files.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Add the notion of warnings when loading rules, which are printed if
verbose is true:
- load_rules now returns a tuple (success, required engine version,
error array, warnings array) instead of (true, required engine
version) or (false, error string)
- build_error/build_error_with_context now returns an array instead of
string value.
- warnings are combined across calls to load_rules_doc
- Current warnings include:
- a rule that contains an unknown filter
- a macro not referred to by any rule
- a list not referred to by any rule/macro/list
Any errors/warnings are concatenated into the exception if success was
false. Any errors/warnings will be printed if verbose is true.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Fixes#1269
Add two new fields in the version service for falco's engine version and
the checksum of all of the fields it understands.
This will require rebuilding/re-releasing all the clients.
Signed-off-by: Spencer Krum <nibz@spencerkrum.com>
