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WIP: Add better filter capabilities to kubernetes tools #744

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984c577
Update kubernetes.yaml
aantn Jul 29, 2025
20b3ca7
Merge branch 'master' into better-kubernetes-filters
moshemorad Aug 6, 2025
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66 changes: 62 additions & 4 deletions holmes/plugins/toolsets/kubernetes.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -19,12 +19,70 @@ toolsets:
command: "kubectl describe {{ kind }} {{ name }}{% if namespace %} -n {{ namespace }}{% endif %}"

- name: "kubectl_get_by_name"
description: "Run `kubectl get <kind> <name> --show-labels`"
command: "kubectl get --show-labels -o wide {{ kind }} {{ name }}{% if namespace %} -n {{ namespace }}{% endif %}"
description: "Run `kubectl get <kind> <name> --show-labels`. Supports regex filtering with include_pattern and exclude_pattern."
script: |
output=$(kubectl get --show-labels -o wide {{ kind }} {{ name }}{% if namespace %} -n {{ namespace }}{% endif %} 2>&1)
exit_code=$?

if [ $exit_code -ne 0 ]; then
echo "$output"
exit $exit_code
fi

# Apply filters if provided
filtered_output="$output"

{% if include_pattern %}
# Apply include pattern (keep lines matching the pattern)
filtered_output=$(echo "$filtered_output" | grep -E "{{ include_pattern }}" || echo "No matches found for include pattern: {{ include_pattern }}")
{% endif %}

{% if exclude_pattern %}
# Apply exclude pattern (remove lines matching the pattern)
filtered_output=$(echo "$filtered_output" | grep -vE "{{ exclude_pattern }}" || echo "$filtered_output")
{% endif %}

Comment on lines +32 to +44
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⚠️ Potential issue

Unescaped user-supplied regex ⇒ command-injection vector

{{ include_pattern }} / {{ exclude_pattern }} are inserted verbatim inside a double-quoted string that is shell-parsed by grep.
A crafted value containing " ; malicious_cmd # would prematurely close the quotes and execute arbitrary commands.

Mitigate by:

  1. Quoting the patterns with printf %q or similar after rendering, or
  2. Passing the pattern via a variable and using grep -E -- "$pattern".

Example patch (conceptual):

-{% if include_pattern %}
-          filtered_output=$(echo "$filtered_output" | grep -E "{{ include_pattern }}" || echo "No matches found for include pattern: {{ include_pattern }}")
-{% endif %}
+{% if include_pattern %}
+          inc_pattern="{{ include_pattern }}"
+          filtered_output=$(echo "$filtered_output" | grep -E -- "$inc_pattern" || { 
+              echo "No matches found for include pattern: $inc_pattern"; exit 0; })
+{% endif %}
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
# Apply filters if provided
filtered_output="$output"
{% if include_pattern %}
# Apply include pattern (keep lines matching the pattern)
filtered_output=$(echo "$filtered_output" | grep -E "{{ include_pattern }}" || echo "No matches found for include pattern: {{ include_pattern }}")
{% endif %}
{% if exclude_pattern %}
# Apply exclude pattern (remove lines matching the pattern)
filtered_output=$(echo "$filtered_output" | grep -vE "{{ exclude_pattern }}" || echo "$filtered_output")
{% endif %}
# Apply filters if provided
filtered_output="$output"
{% if include_pattern %}
# Apply include pattern (keep lines matching the pattern)
inc_pattern="{{ include_pattern }}"
filtered_output=$(echo "$filtered_output" | grep -E -- "$inc_pattern" || {
echo "No matches found for include pattern: $inc_pattern"; exit 0; })
{% endif %}
{% if exclude_pattern %}
# Apply exclude pattern (remove lines matching the pattern)
filtered_output=$(echo "$filtered_output" | grep -vE "{{ exclude_pattern }}" || echo "$filtered_output")
{% endif %}
🤖 Prompt for AI Agents 
In holmes/plugins/toolsets/kubernetes.yaml around lines 32 to 44, the
include_pattern and exclude_pattern are directly inserted into grep commands
inside double quotes, creating a command injection risk. To fix this, avoid
embedding the patterns directly in the command string; instead, assign the
rendered patterns to shell variables and pass them safely to grep using the
syntax grep -E -- "$pattern". This prevents shell interpretation of special
characters and mitigates injection vulnerabilities.

echo "$filtered_output"

- name: "kubectl_get_by_kind_in_namespace"
description: "Run `kubectl get <kind> -n <namespace> --show-labels` to get all resources of a given type in namespace"
command: "kubectl get --show-labels -o wide {{ kind }} -n {{namespace}}"
description: "Run `kubectl get <kind> -n <namespace> --show-labels` to get all resources of a given type in namespace. Supports regex filtering with include_pattern and exclude_pattern."
script: |
output=$(kubectl get --show-labels -o wide {{ kind }} -n {{namespace}} 2>&1)
exit_code=$?

if [ $exit_code -ne 0 ]; then
echo "$output"
exit $exit_code
fi

# Save header line
header=$(echo "$output" | head -n 1)
body=$(echo "$output" | tail -n +2)

# Apply filters if provided
filtered_body="$body"

{% if include_pattern %}
# Apply include pattern (keep lines matching the pattern)
filtered_body=$(echo "$filtered_body" | grep -E "{{ include_pattern }}" || echo "")
if [ -z "$filtered_body" ]; then
echo "$header"
echo "No matches found for include pattern: {{ include_pattern }}"
exit 0
fi
{% endif %}

{% if exclude_pattern %}
# Apply exclude pattern (remove lines matching the pattern)
temp=$(echo "$filtered_body" | grep -vE "{{ exclude_pattern }}" || echo "")
if [ -n "$temp" ]; then
filtered_body="$temp"
fi
{% endif %}

# Output header and filtered body
echo "$header"
echo "$filtered_body"

- name: "kubectl_get_by_kind_in_cluster"
description: "Run `kubectl get -A <kind> --show-labels` to get all resources of a given type in the cluster"
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