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https://github.com/netbirdio/netbird.git
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mlsmaycon
e0ede59d68
A service reads LocalMachine\MY, where AD and Intune enrol device certificates. CurrentUser\MY lives in the signed-in user's registry hive with keys protected against their profile, and a service that opens it does not fail: "current user" resolves to HKU\S-1-5-18, so it silently reads the service account's own empty store. The service therefore reads the machine store itself and launches "netbird posture cert-proof" with the session token for the rest, mirroring the macOS console user helper. Windows lets a privileged service assume a user identity, so the token goes straight into the child process and no external tooling is involved. CREATE_NO_WINDOW keeps a console window from flashing on the desktop every sync. In-process impersonation would also work but is per OS thread while goroutines migrate, so the child process avoids that class of bug. Session selection prefers the physical console and falls back to any active session, so remote desktop and VDI hosts are covered. WTSQueryUserToken needs SE_TCB_NAME, so a user-run client skips the helper and reads the machine store alone. SystemStore takes a store location, gaining NewUserStore alongside NewSystemStore and the per candidate logging macOS already had. The request building and proof merging move to helper_spawn.go, shared by both platforms, and helperStore picks what the helper reads per platform.
97 lines
3.2 KiB
Go
97 lines
3.2 KiB
Go
package certproof
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import (
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"bytes"
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"context"
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"encoding/json"
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"fmt"
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"os"
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"os/exec"
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"strconv"
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"strings"
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"time"
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log "github.com/sirupsen/logrus"
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"github.com/netbirdio/netbird/shared/management/certposture"
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"github.com/netbirdio/netbird/shared/management/proto"
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)
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const helperTimeout = 30 * time.Second
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// CollectProofs answers the certificate challenges in checks from every store this Mac
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// can reach. The root daemon reads the System keychain itself, which is where MDM
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// installs device identities, and reaches the console user's login keychain only by
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// launching a helper into that user's session. A Mac sitting at the login window
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// therefore yields device proofs alone.
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func CollectProofs(ctx context.Context, checks []*proto.Checks, peerKey []byte) []certposture.Proof {
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challenges := certificateChallenges(checks)
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if len(challenges) == 0 {
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logNoChallenges(checks)
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return nil
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}
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// A helper already runs inside the user's session, so it reads its own keychain
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// directly and must never launch another one.
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if os.Geteuid() != 0 {
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return CollectChallenges(ctx, DefaultStore(), challenges, peerKey)
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}
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proofs := CollectChallenges(ctx, DefaultStore(), challenges, peerKey)
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userProofs, err := collectAsConsoleUser(ctx, challenges, peerKey)
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if err != nil {
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log.Infof("certificate posture: console user keychain unavailable: %v", err)
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}
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return mergeProofs(proofs, userProofs)
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}
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// collectAsConsoleUser runs the helper inside the desktop session of the logged-in
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// user. Dropping to their uid is not enough: keychain access is an XPC call to a
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// per-session securityd, so the helper has to enter their Mach bootstrap namespace,
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// which is what launchctl asuser does.
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func collectAsConsoleUser(ctx context.Context, challenges []*proto.CertificateChallenge, peerKey []byte) ([]certposture.Proof, error) {
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user, ok := CurrentConsoleUser()
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if !ok {
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return nil, nil
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}
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binary, err := os.Executable()
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if err != nil {
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return nil, fmt.Errorf("resolve own binary: %w", err)
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}
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payload, err := json.Marshal(helperRequest(challenges, peerKey))
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if err != nil {
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return nil, fmt.Errorf("encode helper request: %w", err)
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}
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ctx, cancel := context.WithTimeout(ctx, helperTimeout)
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defer cancel()
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uid := strconv.FormatUint(uint64(user.UID), 10)
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cmd := exec.CommandContext(ctx, "launchctl", "asuser", uid, "sudo", "-u", user.Name, "-H", binary, "posture", "cert-proof")
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cmd.Stdin = bytes.NewReader(payload)
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var stdout, stderr bytes.Buffer
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cmd.Stdout = &stdout
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cmd.Stderr = &stderr
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log.Infof("certificate posture: asking the desktop session of %q (uid %s) to answer %d challenges", user.Name, uid, len(challenges))
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if err := cmd.Run(); err != nil {
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return nil, fmt.Errorf("run helper as %s: %w: %s", user.Name, err, strings.TrimSpace(stderr.String()))
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}
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var resp HelperResponse
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if err := json.Unmarshal(stdout.Bytes(), &resp); err != nil {
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return nil, fmt.Errorf("decode helper response: %w", err)
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}
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log.Infof("certificate posture: desktop session of %q returned %d proofs", user.Name, len(resp.Proofs))
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return resp.Proofs, nil
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}
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// helperStore is the store the helper reads. On macOS the keychain search list of the
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// user's own session already is that user's keychain, so the platform default is right.
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func helperStore() Store {
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return DefaultStore()
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}
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