Currently, when calling enable_rule, the provided rule name pattern is a
substring match, that is if the rules file has a rule "My fantastic
rule", and you call engine->enable_rule("fantastic", true), the rule
will be enabled.
This can cause problems if one rule name is a complete subset of another
rule name e.g. rules "My rule" and "My rule is great", and calling
engine->enable_rule("My rule", true).
To allow for this case, add an alternate method enable_rule_exact() in
both default ruleset and ruleset variants. In this case, the rule name
must be an exact match.
In the underlying ruleset code, add a "match_exact" option to
falco_ruleset::enable() that denotes whether the substring is an exact
or substring match.
This doesn't change the default behavior of falco in any way, as the
existing calls still use enable_rule().
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
BAN_ALTERNATIVE is same as BAN but the message also provides an alternative
function that the user could use instead of the banned function.
Fixes#1035
Signed-off-by: Vaibhav <vrongmeal@gmail.com>
These include:
* vsprintf()
* sprintf()
* strcat()
* strncat()
* strncpy()
* swprintf()
* vswprintf()
This also changes `userspace/falco/logger.cpp` to remove a `sprintf`
statement. The statement did not affect the codebase in any form so
it was simply removed rather than being substituted.
Fixes#1035
Signed-off-by: Vaibhav <vrongmeal@gmail.com>
This defines certain functions as invalid tokens, i.e., when
compiled, the compiler throws an error.
Currently only `strcpy` is included as a banned function.
Fixes#788
Signed-off-by: Vaibhav <vrongmeal@gmail.com>
Callers aren't expected to catch execeptions and instead rely on the
bool return value to indicate whether or not the parsing was successful.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Currently, the json object POSTed to the /k8s_audit endpoint is assumed
to be an obect, with a "type" of either "Event" or "EventList". When the
K8s API Server POSTs events, it aggregates them into an EventList,
ensuring that there is always a single object.
However, we're going to add some intermediate tools that tail log files
and send them to the endpoint, and the easiest way to send a batch of
events is to pass them as a json array instead of a single object.
To properly handle this, modify parse_k8s_audit_event_json to also
handle a json array. For arrays, it iterates over the objects, calling
parse_k8s_audit_json recursively. This only iterates an initial top
level array to avoid excessive recursion/attacks involving degenerate
json objects with excessively nested arrays.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
In all extraction functions, always catch json type errors alongside
json out of range errors. Both cases result in not extracting any value
from the event.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
First of a handful of PRs to start clarifying the independence of Falco
I don't see any breaking changes here, just cosmetic changes.
Signed-off-by: Kris Nova <kris@nivenly.com>
The call to rule_loader.load_rules only returns 2 values, so only pop
two values from the stack. This fixes#906.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
As a part of the changes in
https://github.com/falcosecurity/falco/pull/826/, we added several
breaking changes to rules files like renaming/removing some filter
fields. This isn't ideal for customers who are using their own rules
files.
We shouldn't break older rules files in this way, so add some minimal
backwards compatibility which adds back the fields that were
removed *and* actually used in k8s_audit_rules.yaml. They have the same
functionality as before. One exception is
ka.req.binding.subject.has_name, which was only used in a single output
field for debugging and shouldn't have been in the rules file in the
first place. This always returns the string "N/A".
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Support the notion of a message for all fields in a single class, and
making sure it's wrapped as well as the other fields.
This is used to display a single message about how indexing working for
ka.* filter fields and what IDX_ALLOWED/IDX_NUMERIC/IDX_KEY means,
rather than repeating the same text over and over in every field.
The wrapping is handled by a function falco::utils::wrap_text.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Refactor how JSON event/k8s audit events extract values in two important
ways:
1. An event can now extract multiple values.
2. The extracted value is a class json_event_value instead of a simple
string.
The driver for 1. was that some filtercheck fields like
"ka.req.container.privileged" actually should extract multiple values,
as a pod can have multiple containers and it doesn't make sense to
summarize that down to a single value.
The driver for 2. is that by having an object represent a single
extracted value, you can also hold things like numbers e.g. ports, uids,
gids, etc. and ranges e.g. [0:3]. With an object, you can override
operators ==, <, etc. to do comparisons between the numbers and ranges,
or even set membership tests between extracted numbers and sets of
ranges.
This is really handy for a lot of new fields implemented as a part of
PSP support, where you end up having to check for overlaps between the
paths, images, ports, uids, etc in a K8s Audit Event and the acceptable
values, ranges, path prefixes enumerated in a PSP.
Implementing these changes also involve an overhaul of how aliases are
implemented. Instead of having an optional "formatting" function, where
arguments to the formatting function were expressed as text within the
index, define optional extraction and indexing functions. If an
extraction function is defined, it's responsible for taking the full
json object and calling add_extracted_value() to add values. There's a
default extraction function that uses a list of json_pointers with
automatic iteration over array values returned by a json pointer.
There's still a notion of filter fields supporting indexes--that's
simply handled within the default extraction or custom extraction
function. And for most fields, there won't be a need to write a custom
extraction function simply to implement indexing.
Within a json_event_filter_check object, instead of having a single
extracted value as a string, hold a vector of extracted json_event_value
objects (vector because order matters) and a set of json_event_value
objects (for set comparisons) as m_evalues. Values on the right hand
side of the expression are held as a set m_values.
json_event_filter_check::compare now supports IN/INTERSECTS as set
comparisons. It also supports PMATCH using path_prefix_search objects,
which simplifies checks like ka.req.pod.volumes.hostpath--now they can
be expressed as "ka.req.pod.volumes.hostpath intersects (/proc,
/var/run/docker.sock, /, /etc, /root)" instead of
"ka.req.volume.hostpath[/proc]=true or
ka.req.volume.hostpath[/root]=true or ...".
Define ~10 new filtercheck fields that extract pod properties like
hostIpc, readOnlyRootFilesystem, etc. that are relevant for PSP validation.
As a part of these changes, also clarify the names of filter fields
related to pods to always have a .pod in the name. Furthermore, fields
dealing with containers in a pod always have a .pod.containers prefix in
the name.
Finally, change the comparisons for existing k8s audit rules to use
"intersects" and/or "in" when appropriate instead of a single equality
comparison.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Related to the changes in https://github.com/draios/sysdig/pull/1501,
add support for an "intersects" operator that verifies if any of the
values in the rhs of an expression are found in the set of extracted
values.
For example:
(a,b,c) in (a,b) is false, but (a,b,c) intersects (a,b) is true.
The code that implements CO_INTERSECTS is in a different commit.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
If this work as intended PR will automatically get the area labels depending on the files he modified.
In case the user wants it can still apply other areas manually, by slash command, or editing the PR template during the opening of the PR.
Signed-off-by: Leonardo Di Donato <leodidonato@gmail.com>
Properly parse multi-document yaml files e.g. blocks separated by
---. This is easily handled by lyaml itself--you just need to pass the
option all = true to yaml.load, and each document will be provided as a table.
This does break the table iteration a bit, so some more refactoring:
- Create a load_state table that holds context like the current
- document index, the required_engine_version, etc.
- Pull out the parts that parse a single document to load_rules_doc(),
which is given the table for a single document + load_state.
- Simplify get_orig_yaml_obj to just provide a single row index and
- return all rows from that point to the next blank line or line
starting with '-'
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Make additional improvements to display relevant context when validating
files. This handles cases where a macro/rule overwrites a prior rule.
- Instead of saving the index into the array of lines for each rule,
save the rule yaml itself, as a property 'context' for each object.
- When appending rules, the context of the base macro/rule and the
context of the appended rule/macro are concatenated.
- New functions get_orig_yaml_obj, build_error, and
build_error_with_context handle building the error string.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Fix a couple of small bugs when verifying macro/rule objects:
1) Yaml can have document separators "---", and those were mistakenly
being considered array items.
2) When reading macros and rules and using array position to find the
right document offset, the overall object order should be
used (e.g. this is the 5th object from the file) and not the array
position (e.g. this is the 3rd rule from the file).
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Given the compiler we currently use, you can't actually enable/disable
regexes in falco_engine::enable_rule using a regex pattern. The regex
either will fail to compile or will compile but not actually match
strings. This is noted on the c++11 compatibility notes for gcc 4.8.2:
https://gcc.gnu.org/onlinedocs/gcc-4.8.2/libstdc++/manual/manual/status.html#status.iso.2011.
The only use of using enable_rule was treating the regex pattern as a
substring match anyway, so we can change the engine to treat the pattern
as a substring.
So change the method/supporting sub-classes to note that the argument is
a substring match, and change falco itself to refer to substrings
instead of patterns.
This fixes https://github.com/falcosecurity/falco/issues/742.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
Instead of relying on lua errors to pass back parse errors, pass back an
explicit true + required engine version or false + error message.
Also clean up the error message to display info + context on the
error. When the error related to yaml parsing, use the row number passed
back in lyaml's error string to print the specific line with the error.
When parsing rules/macros/lists, print the object being parsed alongside
the error.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
To speed up list expansion, instead of using regexes to replace a list
name with its contents, do string searches followed by examining the
preceding/following characters for the proper delimiter.
Signed-off-by: Mark Stemm <mark.stemm@gmail.com>
