4725a1b080
Skip empty fingerprints in SystemPromptLeakGuardrail to prevent blank
values from flagging every message. Replace overly broad "sk-" pattern
in SensitiveDataGuardrail with specific LLM provider prefixes
("sk-proj-" for OpenAI, "sk-ant-" for Anthropic) to avoid false
positives on common words like "risk-based" or "task-management".
Signed-off-by: Bryan Frimin <bryan@getprobo.com>
99 lines
2.9 KiB
Go
99 lines
2.9 KiB
Go
// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice appear in all copies.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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// PERFORMANCE OF THIS SOFTWARE.
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package guardrail
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import (
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"context"
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_ "embed"
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"strings"
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"go.gearno.de/kit/log"
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"go.probo.inc/probo/pkg/agent"
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"go.probo.inc/probo/pkg/llm"
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)
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//go:embed prompt_injection_classifier.txt
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var promptInjectionClassifierPrompt string
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type PromptInjectionGuardrail struct {
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client *llm.Client
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logger *log.Logger
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}
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func NewPromptInjectionGuardrail(client *llm.Client, logger *log.Logger) *PromptInjectionGuardrail {
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return &PromptInjectionGuardrail{client: client, logger: logger}
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}
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func (g *PromptInjectionGuardrail) Name() string {
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return "prompt-injection"
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}
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func (g *PromptInjectionGuardrail) Check(ctx context.Context, messages []llm.Message) (*agent.GuardrailResult, error) {
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if len(messages) == 0 {
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return &agent.GuardrailResult{Tripwire: false}, nil
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}
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// Only classify the last user message.
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lastMessage := messages[len(messages)-1]
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if lastMessage.Role != llm.RoleUser {
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return &agent.GuardrailResult{Tripwire: false}, nil
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}
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userText := lastMessage.Text()
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if userText == "" {
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return &agent.GuardrailResult{Tripwire: false}, nil
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}
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resp, err := g.client.ChatCompletion(
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ctx,
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&llm.ChatCompletionRequest{
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Model: "gpt-4o-mini",
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Messages: []llm.Message{
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{
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Role: llm.RoleSystem,
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Parts: []llm.Part{llm.TextPart{Text: promptInjectionClassifierPrompt}},
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},
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{
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Role: llm.RoleUser,
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Parts: []llm.Part{llm.TextPart{Text: userText}},
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},
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},
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MaxTokens: new(10),
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Temperature: new(0.0),
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},
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)
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if err != nil {
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// If the classifier fails, allow the message through rather than
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// blocking legitimate users. The system prompt hardening and
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// tool-level authorization provide defense in depth.
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g.logger.WarnCtx(
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ctx,
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"prompt injection classifier failed, allowing message through",
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log.Error(err),
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)
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return &agent.GuardrailResult{Tripwire: false}, nil
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}
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responseText := strings.TrimSpace(resp.Message.Text())
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if strings.EqualFold(responseText, "UNSAFE") {
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return &agent.GuardrailResult{
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Tripwire: true,
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Message: "message classified as prompt injection attempt",
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}, nil
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}
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return &agent.GuardrailResult{Tripwire: false}, nil
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}
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