309 lines
8.3 KiB
Go
309 lines
8.3 KiB
Go
package main
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import (
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"bytes"
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"context"
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"fmt"
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"io"
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"os"
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"os/exec"
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"path/filepath"
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"regexp"
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"strings"
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"sync"
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"time"
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)
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var dangerousPatterns = []*regexp.Regexp{
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regexp.MustCompile(`rm\s+(-[a-z]*r[a-z]*\s+)*-[a-z]*f[a-z]*\s*/(home|var|usr|etc|boot|root|bin|sbin|lib|opt|srv)?`), // rm -rf, rm -r -f on sensitive paths
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regexp.MustCompile(`rm\s+(-[a-z]*f[a-z]*\s+)*-[a-z]*r[a-z]*\s*/(home|var|usr|etc|boot|root|bin|sbin|lib|opt|srv)?`), // rm -fr, rm -f -r on sensitive paths
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regexp.MustCompile(`rm\s+.*--recursive.*--force`), // rm --recursive --force
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regexp.MustCompile(`rm\s+.*--force.*--recursive`), // rm --force --recursive
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regexp.MustCompile(`rm\s+(-[a-z]*r[a-z]*\s+)*-[a-z]*f[a-z]*\s+\.\.?(/|$)`), // rm -rf ./ or rm -rf ../
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regexp.MustCompile(`rm\s+(-[a-z]*r[a-z]*\s+)*-[a-z]*f[a-z]*\s+~`), // rm -rf ~ (home dir)
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regexp.MustCompile(`rm\s+(-[a-z]*r[a-z]*\s+)*-[a-z]*f[a-z]*\s+\*`), // rm -rf * (glob expansion)
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regexp.MustCompile(`:\s*\(\s*\)\s*\{\s*:\s*\|\s*:\s*&`), // fork bomb
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regexp.MustCompile(`\bmkfs\b`), // filesystem format
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regexp.MustCompile(`\bdd\b.*\bif=/dev/`), // dd from device
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regexp.MustCompile(`\bchmod\s+777\b`), // world-writable
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regexp.MustCompile(`\b(curl|wget)\s+\S*://`), // network fetch (any protocol)
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regexp.MustCompile(`>\s*/dev/`), // write to device
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regexp.MustCompile(`\beval\s*\(`), // eval execution
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regexp.MustCompile(`\bexec\s*\(`), // exec execution
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regexp.MustCompile(`\b(sudo|su)\b`), // privilege escalation
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regexp.MustCompile(`/etc/(passwd|shadow|sudoers)`), // sensitive files
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}
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var whitespacePattern = regexp.MustCompile(`\s+`)
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// Rate limiting for validation failures
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var (
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rateLimitMu sync.Mutex
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validationFailures int
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lastFailure time.Time
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blockedUntil time.Time
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)
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const (
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maxFailures = 5
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blockDuration = 30 * time.Second
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failureWindow = 60 * time.Second
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)
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func checkRateLimit() error {
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rateLimitMu.Lock()
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defer rateLimitMu.Unlock()
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now := time.Now()
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if now.Before(blockedUntil) {
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remaining := blockedUntil.Sub(now).Round(time.Second)
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return fmt.Errorf("rate limited: too many validation failures, blocked for %v", remaining)
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}
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return nil
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}
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func recordValidationFailure() {
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rateLimitMu.Lock()
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defer rateLimitMu.Unlock()
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now := time.Now()
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// Reset counter if outside failure window
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if now.Sub(lastFailure) > failureWindow {
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validationFailures = 0
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}
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validationFailures++
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lastFailure = now
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if validationFailures >= maxFailures {
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blockedUntil = now.Add(blockDuration)
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validationFailures = 0
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logSecurityEvent(SecurityEvent{
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Timestamp: now,
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EventType: "rate_limit_triggered",
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Details: fmt.Sprintf("blocked for %v after %d failures", blockDuration, maxFailures),
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})
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}
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}
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func validateCode(code string) error {
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if err := checkRateLimit(); err != nil {
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return err
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}
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// Normalize: collapse whitespace, lowercase for pattern matching
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normalized := strings.ToLower(code)
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normalized = whitespacePattern.ReplaceAllString(normalized, " ")
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for _, pattern := range dangerousPatterns {
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if pattern.MatchString(normalized) {
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recordValidationFailure()
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logSecurityEvent(SecurityEvent{
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Timestamp: time.Now(),
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EventType: "validation_failure",
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Details: fmt.Sprintf("dangerous pattern: %s", pattern.String()),
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})
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return fmt.Errorf("dangerous pattern detected")
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}
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}
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return nil
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}
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func executeCode(code, language string, timeout int) (string, error) {
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start := time.Now()
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if timeout <= 0 {
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timeout = 30
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}
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if err := validateCode(code); err != nil {
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logExecution(ExecutionLog{
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Timestamp: start,
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CodeHash: hashCode(code),
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Language: language,
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Duration: time.Since(start),
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Success: false,
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OutputSize: 0,
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Error: err.Error(),
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})
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return "", err
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}
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homeDir, err := os.UserHomeDir()
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if err != nil {
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return "", fmt.Errorf("failed to get home dir: %v", err)
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}
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workspaceBase := filepath.Join(homeDir, ".cache", "anvillm", "exec")
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if err := os.MkdirAll(workspaceBase, 0700); err != nil {
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return "", fmt.Errorf("failed to create workspace base: %v", err)
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}
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workDir, err := os.MkdirTemp(workspaceBase, "anvilmcp-*")
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if err != nil {
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return "", fmt.Errorf("failed to create workspace: %v", err)
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}
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defer os.RemoveAll(workDir)
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ctx, cancel := context.WithTimeout(context.Background(), time.Duration(timeout)*time.Second)
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defer cancel()
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// Check for landrun
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landrunPath, err := exec.LookPath("landrun")
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if err != nil {
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return "", fmt.Errorf("landrun not found: %v", err)
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}
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// Get namespace for 9p access
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namespace := os.Getenv("NAMESPACE")
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if namespace == "" {
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namespace = fmt.Sprintf("/tmp/ns.%s.:0", os.Getenv("USER"))
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}
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// Get AGENT_ID if set
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agentID := os.Getenv("AGENT_ID")
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var cmd *exec.Cmd
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switch language {
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case "bash", "":
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args := []string{
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"--rwx", workDir,
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"--unrestricted-network",
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}
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// Add common system paths if they exist
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systemPaths := []struct {
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flag string
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path string
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}{
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{"--rox", "/usr"},
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{"--rox", "/lib"},
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{"--rox", "/lib64"},
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{"--rox", "/bin"},
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{"--ro", "/etc/alternatives"},
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{"--ro", "/etc/ld.so.cache"},
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{"--rw", "/dev/null"},
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{"--ro", "/dev/urandom"},
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}
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for _, sp := range systemPaths {
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if _, err := os.Stat(sp.path); err == nil {
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args = append(args, sp.flag, sp.path)
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}
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}
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// Add namespace if set
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if namespace != "" {
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args = append(args, "--rw", namespace)
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}
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// Add common user binary directories
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userBinDirs := []string{
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filepath.Join(homeDir, "bin"),
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filepath.Join(homeDir, ".local", "bin"),
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filepath.Join(homeDir, "opt"),
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filepath.Join(homeDir, "go", "bin"),
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}
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// Add PLAN9 bin if set
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if plan9 := os.Getenv("PLAN9"); plan9 != "" {
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userBinDirs = append(userBinDirs, filepath.Join(plan9, "bin"))
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}
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for _, dir := range userBinDirs {
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if _, err := os.Stat(dir); err == nil {
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args = append(args, "--rox", dir)
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}
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}
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args = append(args,
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"--env", "NAMESPACE",
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"--env", "PATH",
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"--env", "HOME",
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"--env", "PLAN9",
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)
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if agentID != "" {
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args = append(args, "--env", "AGENT_ID")
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}
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args = append(args, "--", "bash", "-c", code)
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cmd = exec.CommandContext(ctx, landrunPath, args...)
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cmd.Dir = workDir
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default:
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return "", fmt.Errorf("unsupported language: %s (only bash supported)", language)
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}
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// Limit output size (10MB)
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var outputBuf bytes.Buffer
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lw := &limitedWriter{w: &outputBuf, limit: 10 * 1024 * 1024}
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cmd.Stdout = lw
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cmd.Stderr = lw
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err = cmd.Run()
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output := outputBuf.Bytes()
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// Append truncation notice if output was truncated
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if lw.truncated {
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output = append(output, []byte("\n[output truncated at 10MB]")...)
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}
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duration := time.Since(start)
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execLog := ExecutionLog{
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Timestamp: start,
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CodeHash: hashCode(code),
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Language: language,
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Duration: duration,
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Success: err == nil && ctx.Err() != context.DeadlineExceeded,
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OutputSize: len(output),
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}
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if ctx.Err() == context.DeadlineExceeded {
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execLog.Error = fmt.Sprintf("execution timeout after %d seconds", timeout)
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logExecution(execLog)
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logSecurityEvent(SecurityEvent{
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Timestamp: start,
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EventType: "timeout",
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Language: language,
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Details: fmt.Sprintf("timeout after %d seconds", timeout),
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})
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return "", fmt.Errorf("execution timeout after %d seconds", timeout)
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}
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if err != nil {
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execLog.Error = err.Error()
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logExecution(execLog)
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return string(output), fmt.Errorf("execution failed: %v\nOutput: %s", err, string(output))
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}
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logExecution(execLog)
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return string(output), nil
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}
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type limitedWriter struct {
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w io.Writer
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written int
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limit int
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truncated bool
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}
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func (lw *limitedWriter) Write(p []byte) (n int, err error) {
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if lw.written >= lw.limit {
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lw.truncated = true
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return len(p), nil // Discard, report all bytes consumed
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}
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remaining := lw.limit - lw.written
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toWrite := p
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if len(p) > remaining {
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toWrite = p[:remaining]
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lw.truncated = true
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}
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written, err := lw.w.Write(toWrite)
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lw.written += written
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if err != nil {
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return written, err
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}
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return len(p), nil // Report all input bytes as consumed
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}
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