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| 1 | +// Copyright 2025 CoreOS, Inc. |
| 2 | +// |
| 3 | +// Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | +// you may not use this file except in compliance with the License. |
| 5 | +// You may obtain a copy of the License at |
| 6 | +// |
| 7 | +// http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | +// |
| 9 | +// Unless required by applicable law or agreed to in writing, software |
| 10 | +// distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | +// See the License for the specific language governing permissions and |
| 13 | +// limitations under the License. |
| 14 | + |
| 15 | +package attestation |
| 16 | + |
| 17 | +import ( |
| 18 | + "bytes" |
| 19 | + "crypto/tls" |
| 20 | + "crypto/x509" |
| 21 | + "encoding/json" |
| 22 | + "encoding/pem" |
| 23 | + "errors" |
| 24 | + "fmt" |
| 25 | + "net" |
| 26 | + "net/http" |
| 27 | + "os" |
| 28 | + "os/exec" |
| 29 | + "syscall" |
| 30 | + "time" |
| 31 | + |
| 32 | + "github.com/coreos/ignition/v2/config/util" |
| 33 | + "github.com/coreos/ignition/v2/config/v3_6_experimental/types" |
| 34 | + "github.com/coreos/ignition/v2/internal/log" |
| 35 | + "github.com/coreos/ignition/v2/internal/resource" |
| 36 | +) |
| 37 | + |
| 38 | +const ( |
| 39 | + TPMDir = "/var/tpm" |
| 40 | + AKPath = "/var/tpm/ak.pub" |
| 41 | + AKCtxPath = "/var/tpm/ak.ctx" |
| 42 | + AKRegisterd = "/var/tpm/ak.registerd" |
| 43 | + AKHandle = "0x81010002" |
| 44 | + EKHandle = "0x81010001" |
| 45 | +) |
| 46 | + |
| 47 | +func HandleAttestation(logger *log.Logger, cfg *types.Config, platformName string, needNetPath string) error { |
| 48 | + if !util.NilOrEmpty(cfg.Attestation.AttestationKey.Registration.Url) { |
| 49 | + // Generate and persist the AK |
| 50 | + if err := GenerateAndPersistAK(logger); err != nil { |
| 51 | + return err |
| 52 | + } |
| 53 | + |
| 54 | + attestationKeyBytes, err := os.ReadFile(AKPath) |
| 55 | + if err != nil { |
| 56 | + return err |
| 57 | + } |
| 58 | + attestationKey := string(attestationKeyBytes) |
| 59 | + |
| 60 | + // Check if the neednet file exists to determine our retry behavior |
| 61 | + _, needNetErr := os.Stat(needNetPath) |
| 62 | + needNetExists := (needNetErr == nil) |
| 63 | + if needNetExists { |
| 64 | + logger.Info("neednet file exists, network should be available for attestation") |
| 65 | + } else { |
| 66 | + logger.Info("neednet file does not exist, will return ErrNeedNet if network is unavailable") |
| 67 | + } |
| 68 | + |
| 69 | + err = AttestationKeyRegistration(logger, cfg.Attestation.AttestationKey.Registration, |
| 70 | + attestationKey, platformName) |
| 71 | + if err != nil { |
| 72 | + // If we got ErrNeedNet and the neednet file doesn't exist, propagate it |
| 73 | + // (we're in fetch-offline and need to signal for network) |
| 74 | + if err == resource.ErrNeedNet && !needNetExists { |
| 75 | + return err |
| 76 | + } |
| 77 | + // If we got ErrNeedNet but neednet file exists, we're in fetch stage |
| 78 | + // Retry the registration with delays to allow network to come up |
| 79 | + if err == resource.ErrNeedNet && needNetExists { |
| 80 | + logger.Info("Network not ready yet in fetch stage, retrying with delays...") |
| 81 | + // Retry up to 10 times with increasing delays |
| 82 | + maxRetries := 20 |
| 83 | + for attempt := 2; attempt <= maxRetries; attempt++ { |
| 84 | + delay := time.Duration(min(attempt*2, 10)) * time.Second |
| 85 | + logger.Info("Waiting %v before retry attempt %d/%d", delay, attempt, maxRetries) |
| 86 | + time.Sleep(delay) |
| 87 | + |
| 88 | + err = AttestationKeyRegistration(logger, cfg.Attestation.AttestationKey.Registration, |
| 89 | + attestationKey, platformName) |
| 90 | + if err == nil { |
| 91 | + break |
| 92 | + } |
| 93 | + logger.Info("Attestation registration attempt %d/%d failed: %v", attempt, maxRetries, err) |
| 94 | + } |
| 95 | + if err != nil { |
| 96 | + return fmt.Errorf("failed to register attestation key after retries: %w", err) |
| 97 | + } |
| 98 | + } else { |
| 99 | + return err |
| 100 | + } |
| 101 | + } |
| 102 | + } |
| 103 | + return nil |
| 104 | +} |
| 105 | + |
| 106 | +// GenerateAndPersistAK creates and persists the Attestation Key in the TPM |
| 107 | +func GenerateAndPersistAK(logger *log.Logger) error { |
| 108 | + if err := os.MkdirAll(TPMDir, 0755); err != nil { |
| 109 | + return fmt.Errorf("couldn't create %s directory: %w", TPMDir, err) |
| 110 | + } |
| 111 | + |
| 112 | + if _, err := os.Stat(AKPath); err == nil { |
| 113 | + logger.Info("Attestation Key already exists, skipping generation") |
| 114 | + return nil |
| 115 | + } |
| 116 | + |
| 117 | + logger.Info("Generating Attestation Key") |
| 118 | + cmd := exec.Command("tpm2_createak", "-C", EKHandle, |
| 119 | + "-c", AKCtxPath, "-G", "rsa", "-g", "sha256", |
| 120 | + "-s", "rsassa", "-u", AKPath, "-f", "pem") |
| 121 | + if _, err := logger.LogCmd(cmd, "creating attestation key"); err != nil { |
| 122 | + return fmt.Errorf("failed to create attestation key: %w", err) |
| 123 | + } |
| 124 | + |
| 125 | + cmd = exec.Command("tpm2_evictcontrol", "-c", AKCtxPath, AKHandle) |
| 126 | + if _, err := logger.LogCmd(cmd, "persisting attestation key"); err != nil { |
| 127 | + return fmt.Errorf("failed to persist attestation key: %w", err) |
| 128 | + } |
| 129 | + |
| 130 | + return nil |
| 131 | +} |
| 132 | + |
| 133 | +// AttestationKeyRegistration sends a request to register an attestation key |
| 134 | +func AttestationKeyRegistration(logger *log.Logger, registration types.Registration, attestationKey string, platform string) error { |
| 135 | + if registration.Url == nil || *registration.Url == "" { |
| 136 | + return fmt.Errorf("registration URL is required") |
| 137 | + } |
| 138 | + // Check if AK was already generated |
| 139 | + if _, err := os.Stat(AKRegisterd); err == nil { |
| 140 | + return nil |
| 141 | + } |
| 142 | + |
| 143 | + requestBody := map[string]string{ |
| 144 | + "attestation_key": attestationKey, |
| 145 | + "platform": platform, |
| 146 | + } |
| 147 | + |
| 148 | + jsonBody, err := json.Marshal(requestBody) |
| 149 | + if err != nil { |
| 150 | + return fmt.Errorf("failed to marshal request body: %w", err) |
| 151 | + } |
| 152 | + |
| 153 | + client := &http.Client{} |
| 154 | + |
| 155 | + if !util.NilOrEmpty(registration.Certificate) { |
| 156 | + tlsConfig, err := createTLSConfig(*registration.Certificate) |
| 157 | + if err != nil { |
| 158 | + return fmt.Errorf("failed to create TLS config: %w", err) |
| 159 | + } |
| 160 | + |
| 161 | + client.Transport = &http.Transport{ |
| 162 | + TLSClientConfig: tlsConfig, |
| 163 | + } |
| 164 | + } |
| 165 | + |
| 166 | + // Single attempt - caller (HandleAttestation) handles retries |
| 167 | + req, err := http.NewRequest(http.MethodPut, *registration.Url, bytes.NewBuffer(jsonBody)) |
| 168 | + if err != nil { |
| 169 | + return fmt.Errorf("failed to create request: %w", err) |
| 170 | + } |
| 171 | + |
| 172 | + req.Header.Set("Content-Type", "application/json") |
| 173 | + |
| 174 | + resp, err := client.Do(req) |
| 175 | + if err != nil { |
| 176 | + // Return network errors as ErrNeedNet for caller to handle |
| 177 | + if isNetworkUnreachable(err) { |
| 178 | + return resource.ErrNeedNet |
| 179 | + } |
| 180 | + return fmt.Errorf("failed to register attestation key: %w", err) |
| 181 | + } |
| 182 | + |
| 183 | + defer resp.Body.Close() |
| 184 | + |
| 185 | + if resp.StatusCode < 200 || resp.StatusCode >= 300 { |
| 186 | + return fmt.Errorf("registration failed with status code: %d", resp.StatusCode) |
| 187 | + } |
| 188 | + |
| 189 | + // Registration successful |
| 190 | + if err := os.WriteFile(AKRegisterd, []byte{}, 0644); err != nil { |
| 191 | + return fmt.Errorf("failed to create AK registered file: %w", err) |
| 192 | + } |
| 193 | + logger.Info("Register successfully the AK") |
| 194 | + return nil |
| 195 | +} |
| 196 | + |
| 197 | +// isNetworkUnreachable checks if the error indicates network is unreachable |
| 198 | +func isNetworkUnreachable(err error) bool { |
| 199 | + var opErr *net.OpError |
| 200 | + if errors.As(err, &opErr) { |
| 201 | + // Check for ENETUNREACH (network unreachable) |
| 202 | + if errors.Is(opErr.Err, syscall.ENETUNREACH) { |
| 203 | + return true |
| 204 | + } |
| 205 | + // Check for EHOSTUNREACH (host unreachable) |
| 206 | + if errors.Is(opErr.Err, syscall.EHOSTUNREACH) { |
| 207 | + return true |
| 208 | + } |
| 209 | + // Check for "connect: network is unreachable" string |
| 210 | + if opErr.Err != nil && opErr.Err.Error() == "network is unreachable" { |
| 211 | + return true |
| 212 | + } |
| 213 | + } |
| 214 | + return false |
| 215 | +} |
| 216 | + |
| 217 | +func createTLSConfig(certPEM string) (*tls.Config, error) { |
| 218 | + block, _ := pem.Decode([]byte(certPEM)) |
| 219 | + if block == nil { |
| 220 | + return nil, fmt.Errorf("failed to decode PEM certificate") |
| 221 | + } |
| 222 | + |
| 223 | + cert, err := x509.ParseCertificate(block.Bytes) |
| 224 | + if err != nil { |
| 225 | + return nil, fmt.Errorf("failed to parse certificate: %w", err) |
| 226 | + } |
| 227 | + |
| 228 | + certPool := x509.NewCertPool() |
| 229 | + certPool.AddCert(cert) |
| 230 | + |
| 231 | + return &tls.Config{ |
| 232 | + RootCAs: certPool, |
| 233 | + }, nil |
| 234 | +} |
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