Introduces support for darwing plist loading

client/mdm/policy.go

@@ -11,6 +11,7 @@ package mdm
 import (
 	"sort"
 	"strconv"
+	"strings"
 
 	log "github.com/sirupsen/logrus"
 )
@@ -75,6 +76,19 @@ var SecretKeys = map[string]struct{}{
 	KeyPreSharedKey: {},
 }
 
+// canonicalKey maps the lowercase form of a managed-config value name to its
+// canonical mdm.Key* form. Admins commonly write PascalCase value names in
+// ADMX / Group Policy ("ManagementURL"), the iOS/AppConfig and macOS plist
+// conventions are camelCase ("managementURL"); both must resolve to the
+// same Policy lookup. Shared across all platform loaders.
+var canonicalKey = func() map[string]string {
+	m := make(map[string]string, len(AllKeys))
+	for _, k := range AllKeys {
+		m[strings.ToLower(k)] = k
+	}
+	return m
+}()
+
 // Policy holds MDM-managed settings read from the platform source. A nil or
 // empty Policy means no enforcement is active.
 type Policy struct {

client/mdm/policy_darwin.go

@@ -2,8 +2,87 @@
 
 package mdm
 
-// loadPlatformPolicy reads the MDM configuration from the macOS managed
-// preferences plist. Phase 1 ships a stub; the real reader lands in Phase 2.
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"strings"
+
+	log "github.com/sirupsen/logrus"
+	"howett.net/plist"
+)
+
+// policyPlistPath is the well-known location where macOS writes the
+// device-level mandatory MDM payload for NetBird. The path is fixed by
+// Apple convention: when an MDM provider (Jamf / Kandji / Mosyle /
+// Intune for Mac / Workspace ONE) pushes a Configuration Profile that
+// contains a com.apple.ManagedClient.preferences payload targeting the
+// bundle id io.netbird.client, the OS materializes the payload here.
+//
+// Read-only — only the OS (root) is supposed to write this file. The
+// loader sanity-checks the file mode and refuses to honour a world-
+// writable plist, as a defense against tampered installs.
+const policyPlistPath = "/Library/Managed Preferences/io.netbird.client.plist"
+
+// loadPlatformPolicy reads the MDM-managed configuration from the macOS
+// managed-preferences plist. Returns:
+//   - (nil, nil)  when the plist is absent (device not MDM-enrolled for
+//     NetBird, or admin has not yet pushed a payload)
+//   - (map, nil)  with N entries when N managed values are present
+//     (N may be 0 — empty plist still signals enrollment to the caller)
+//   - (nil, err)  on permission / parse / safety errors
+//
+// Value-type coercion mirrors the Windows loader: native plist types
+// map naturally onto the Policy accessor expectations (GetString /
+// GetBool / GetInt / GetStringSlice). Unknown top-level keys are
+// logged and skipped so a stray entry in the payload does not block
+// startup.
 func loadPlatformPolicy() (map[string]any, error) {
-	return nil, nil
+	f, err := os.Open(policyPlistPath)
+	if err != nil {
+		if errors.Is(err, fs.ErrNotExist) {
+			// Not enrolled for NetBird. Caller treats nil as
+			// "no MDM source present".
+			return nil, nil
+		}
+		return nil, fmt.Errorf("open %s: %w", policyPlistPath, err)
+	}
+	defer func() {
+		if closeErr := f.Close(); closeErr != nil {
+			log.Warnf("MDM close plist %s: %v", policyPlistPath, closeErr)
+		}
+	}()
+
+	info, err := f.Stat()
+	if err != nil {
+		return nil, fmt.Errorf("stat %s: %w", policyPlistPath, err)
+	}
+	// World-writable plist => tampered install. Refuse rather than
+	// honour potentially attacker-controlled policy values.
+	if info.Mode().Perm()&0o002 != 0 {
+		return nil, fmt.Errorf("refusing to read world-writable MDM source %s (mode %o)",
+			policyPlistPath, info.Mode().Perm())
+	}
+
+	raw := make(map[string]any)
+	if err := plist.NewDecoder(f).Decode(&raw); err != nil {
+		return nil, fmt.Errorf("decode plist %s: %w", policyPlistPath, err)
+	}
+
+	out := make(map[string]any, len(raw))
+	for name, val := range raw {
+		// macOS / AppConfig conventions both use camelCase for managed
+		// preferences keys; canonicalize to the mdm.Key* form so a key
+		// written as "ManagementURL" (PascalCase, rare on macOS but
+		// possible if the admin reused an ADMX-style name) still
+		// resolves.
+		canonical, known := canonicalKey[strings.ToLower(name)]
+		if !known {
+			log.Warnf("MDM ignoring unknown plist key %s: %s", policyPlistPath, name)
+			continue
+		}
+		out[canonical] = val
+	}
+	return out, nil
 }

client/mdm/policy_windows.go

@@ -11,18 +11,6 @@ import (
 	"golang.org/x/sys/windows/registry"
 )
 
-// canonicalKey maps the lowercase form of a registry value name to its
-// canonical mdm.Key* name. Admins commonly write PascalCase value names in
-// ADMX / Group Policy ("ManagementURL"), the iOS/AppConfig convention is
-// camelCase ("managementURL"); both must resolve to the same Policy lookup.
-var canonicalKey = func() map[string]string {
-	m := make(map[string]string, len(AllKeys))
-	for _, k := range AllKeys {
-		m[strings.ToLower(k)] = k
-	}
-	return m
-}()
-
 // policyRegistryPath is the well-known MDM policy registry key for NetBird.
 // Admins push values here through Group Policy, Intune ADMX ingestion, an
 // Intune custom Registry CSP profile, or `reg add` during MSI deployment.