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| 1 | +// Package keyctl implements a `keyctl` based credential helper. Passwords are stored |
| 2 | +// in linux kernel keyring. |
| 3 | +package keyctl |
| 4 | + |
| 5 | +import ( |
| 6 | + "bytes" |
| 7 | + "encoding/base64" |
| 8 | + "fmt" |
| 9 | + "os" |
| 10 | + "os/exec" |
| 11 | + "strconv" |
| 12 | + "strings" |
| 13 | + |
| 14 | + "github.com/docker/docker-credential-helpers/credentials" |
| 15 | + "github.com/jsipprell/keyctl" |
| 16 | + "github.com/pkg/errors" |
| 17 | +) |
| 18 | + |
| 19 | +// Keyctl based credential helper looks for a default keyring inside |
| 20 | +// session keyring. It does all operations inside the default keyring |
| 21 | + |
| 22 | +const defaultKeyringName string = "keyctlCredsStore" |
| 23 | +const persistent int = 1 |
| 24 | + |
| 25 | +// Keyctl handles secrets using Linux Kernel keyring mechanism |
| 26 | +type Keyctl struct{} |
| 27 | + |
| 28 | +func (k Keyctl) createDefaultPersistentKeyring() (string, error) { |
| 29 | + /* Create default persistent keyring. If the keyring for the user |
| 30 | + * already exists, then it returns the id of the existing keyring |
| 31 | + */ |
| 32 | + var errout, out bytes.Buffer |
| 33 | + uid := os.Getuid() |
| 34 | + cmd := exec.Command("keyctl", "get_persistent", "@u", strconv.Itoa(uid)) |
| 35 | + cmd.Stderr = &errout |
| 36 | + cmd.Stdout = &out |
| 37 | + err := cmd.Run() |
| 38 | + if err != nil { |
| 39 | + return "", errors.Wrapf(err, "cannot run keyctl command to create persistent keyring %+v: %s", err, errout.String()) |
| 40 | + } |
| 41 | + persistentKeyringID := out.String() |
| 42 | + if err != nil { |
| 43 | + return "", errors.Wrapf(err, "cannot create or read persistent keyring %+v", err) |
| 44 | + } |
| 45 | + return persistentKeyringID, nil |
| 46 | +} |
| 47 | + |
| 48 | +func (k Keyctl) getDefaultCredsStoreFromPersistent() (keyctl.NamedKeyring, error) { |
| 49 | + var out, errout bytes.Buffer |
| 50 | + persistentKeyringID, err := k.createDefaultPersistentKeyring() |
| 51 | + if err != nil { |
| 52 | + return nil, errors.Wrap(err, "default persistent keyring cannot be created") |
| 53 | + } |
| 54 | + |
| 55 | + defaultSessionKeyring, err := keyctl.SessionKeyring() |
| 56 | + if err != nil { |
| 57 | + return nil, errors.New("errors getting session keyring") |
| 58 | + } |
| 59 | + |
| 60 | + defaultKeyring, err := keyctl.OpenKeyring(defaultSessionKeyring, defaultKeyringName) |
| 61 | + /* if already does not exist we create */ |
| 62 | + if err != nil || defaultKeyring == nil { |
| 63 | + cmd := exec.Command("keyctl", "newring", defaultKeyringName, strings.TrimSuffix(persistentKeyringID, "\n")) |
| 64 | + cmd.Stdout = &out |
| 65 | + cmd.Stderr = &errout |
| 66 | + err := cmd.Run() |
| 67 | + if err != nil { |
| 68 | + return nil, errors.Wrapf(err, "cannot run keyctl command to created credstore keyring %s %s %s", cmd.String(), errout.String(), out.String()) |
| 69 | + } |
| 70 | + } |
| 71 | + /* Search for it again and return the default keyring*/ |
| 72 | + defaultKeyring, err = keyctl.OpenKeyring(defaultSessionKeyring, defaultKeyringName) |
| 73 | + if err != nil { |
| 74 | + return nil, errors.Wrap(err, "failed to lookup default session keyring") |
| 75 | + } |
| 76 | + |
| 77 | + return defaultKeyring, nil |
| 78 | +} |
| 79 | + |
| 80 | +// getDefaultCredsStore is a helper function to get the default credsStore keyring |
| 81 | +func (k Keyctl) getDefaultCredsStore() (keyctl.NamedKeyring, error) { |
| 82 | + if persistent == 1 { |
| 83 | + return k.getDefaultCredsStoreFromPersistent() |
| 84 | + } |
| 85 | + defaultSessionKeyring, err := keyctl.SessionKeyring() |
| 86 | + if err != nil { |
| 87 | + return nil, errors.Wrap(err, "error getting session keyring") |
| 88 | + } |
| 89 | + |
| 90 | + defaultKeyring, err := keyctl.OpenKeyring(defaultSessionKeyring, defaultKeyringName) |
| 91 | + if err != nil || defaultKeyring == nil { |
| 92 | + if defaultKeyring == nil { |
| 93 | + defaultKeyring, err = keyctl.CreateKeyring(defaultSessionKeyring, defaultKeyringName) |
| 94 | + if err != nil { |
| 95 | + return nil, errors.Wrap(err, "failed to create default credsStore keyring") |
| 96 | + } |
| 97 | + } |
| 98 | + } |
| 99 | + |
| 100 | + if defaultKeyring == nil { |
| 101 | + return nil, errors.Wrap(errors.New(""), " nil credstore") |
| 102 | + } |
| 103 | + |
| 104 | + return defaultKeyring, nil |
| 105 | +} |
| 106 | + |
| 107 | +// Add adds new credentials to the keychain. |
| 108 | +func (k Keyctl) Add(creds *credentials.Credentials) error { |
| 109 | + defaultKeyring, err := k.getDefaultCredsStore() |
| 110 | + if err != nil || defaultKeyring == nil { |
| 111 | + return errors.Wrapf(err, "failed to create credsStore entry for %s", creds.ServerURL) |
| 112 | + } |
| 113 | + |
| 114 | + // create a child keyring under default for given url |
| 115 | + encoded := base64.URLEncoding.EncodeToString([]byte(strings.TrimSuffix(creds.ServerURL, "\n"))) |
| 116 | + urlKeyring, err := keyctl.CreateKeyring(defaultKeyring, encoded) |
| 117 | + if err != nil { |
| 118 | + return errors.Wrapf(err, "failed to create keyring for %s", creds.ServerURL) |
| 119 | + } |
| 120 | + |
| 121 | + _, err = urlKeyring.Add(creds.Username, []byte(creds.Secret)) |
| 122 | + if err != nil { |
| 123 | + return errors.Wrapf(err, "failed to add creds to keryring for %s with error: %+v", creds.ServerURL, err) |
| 124 | + } |
| 125 | + return err |
| 126 | +} |
| 127 | + |
| 128 | +// searchHelper function searches for an url inside the default keyring. |
| 129 | +func (k Keyctl) searchHelper(serverURL string) (keyctl.NamedKeyring, string, error) { |
| 130 | + defaultKeyring, err := k.getDefaultCredsStore() |
| 131 | + if err != nil || defaultKeyring == nil { |
| 132 | + return nil, "", fmt.Errorf("searchHelper failed: cannot read defaultCredsStore") |
| 133 | + } |
| 134 | + |
| 135 | + encoded := base64.URLEncoding.EncodeToString([]byte(strings.TrimSuffix(serverURL, "\n"))) |
| 136 | + urlKeyring, err := keyctl.OpenKeyring(defaultKeyring, encoded) |
| 137 | + if err != nil { |
| 138 | + return nil, "", fmt.Errorf("error in reading credsStore for url %s", serverURL) |
| 139 | + } |
| 140 | + if urlKeyring == nil { |
| 141 | + return nil, "", fmt.Errorf("credsStore entry for suplied url %s not found", serverURL) |
| 142 | + } |
| 143 | + |
| 144 | + refs, err := keyctl.ListKeyring(urlKeyring) |
| 145 | + if err != nil { |
| 146 | + return nil, "", fmt.Errorf("key for server url not found") |
| 147 | + } |
| 148 | + if len(refs) < 1 { |
| 149 | + return nil, "", fmt.Errorf("no keys in keyring %s", urlKeyring.Name()) |
| 150 | + } |
| 151 | + |
| 152 | + obj := refs[0] |
| 153 | + id, err := obj.Get() |
| 154 | + if err != nil { |
| 155 | + return nil, "", fmt.Errorf("key for server url not found") |
| 156 | + } |
| 157 | + |
| 158 | + info, err := id.Info() |
| 159 | + if err != nil { |
| 160 | + return nil, "", fmt.Errorf("cannot read info for url key") |
| 161 | + } |
| 162 | + |
| 163 | + return urlKeyring, info.Name, err |
| 164 | +} |
| 165 | + |
| 166 | +// Get returns the username and secret to use for a given registry server URL. |
| 167 | +func (k Keyctl) Get(serverURL string) (string, string, error) { |
| 168 | + if serverURL == "" { |
| 169 | + return "", "", errors.New("missing server url") |
| 170 | + } |
| 171 | + |
| 172 | + serverURL = strings.TrimSuffix(serverURL, "\n") |
| 173 | + urlKeyring, searchData, err := k.searchHelper(serverURL) |
| 174 | + if err != nil { |
| 175 | + return "", "", errors.Wrapf(err, "url not found by searchHelper: %s err: %v", serverURL, err) |
| 176 | + } |
| 177 | + key, err := urlKeyring.Search(searchData) |
| 178 | + if err != nil { |
| 179 | + return "", "", errors.Wrapf(err, "url not found in %+v", urlKeyring) |
| 180 | + } |
| 181 | + secret, err := key.Get() |
| 182 | + if err != nil { |
| 183 | + return "", "", errors.Wrapf(err, "failed to read credentials for %s:%s", serverURL, searchData) |
| 184 | + } |
| 185 | + |
| 186 | + return searchData, string(secret), nil |
| 187 | +} |
| 188 | + |
| 189 | +// Delete removes credentials from the store. |
| 190 | +func (k Keyctl) Delete(serverURL string) error { |
| 191 | + serverURL = strings.TrimSuffix(serverURL, "\n") |
| 192 | + urlKeyring, searchData, err := k.searchHelper(serverURL) |
| 193 | + if err != nil { |
| 194 | + return errors.Wrapf(err, "cannot find server url %s", serverURL) |
| 195 | + } |
| 196 | + |
| 197 | + key, err := urlKeyring.Search(searchData) |
| 198 | + if err != nil { |
| 199 | + return err |
| 200 | + } |
| 201 | + |
| 202 | + err = key.Unlink() |
| 203 | + if err != nil { |
| 204 | + return err |
| 205 | + } |
| 206 | + |
| 207 | + refs, err := keyctl.ListKeyring(urlKeyring) |
| 208 | + if err != nil { |
| 209 | + fmt.Printf("cannot list keyring %s", urlKeyring.Name()) |
| 210 | + } |
| 211 | + if len(refs) == 0 { |
| 212 | + keyctl.UnlinkKeyring(urlKeyring) |
| 213 | + } else { |
| 214 | + return errors.Wrapf(err, "Canot remove keyring as its not empty %s", urlKeyring.Name()) |
| 215 | + } |
| 216 | + |
| 217 | + return err |
| 218 | +} |
| 219 | + |
| 220 | +// List returns the stored URLs and corresponding usernames for a given credentials label |
| 221 | +func (k Keyctl) List() (map[string]string, error) { |
| 222 | + defaultKeyring, err := k.getDefaultCredsStore() |
| 223 | + if err != nil || defaultKeyring == nil { |
| 224 | + return nil, errors.Wrap(err, "List() failed: cannot read default credStore") |
| 225 | + } |
| 226 | + |
| 227 | + resp := map[string]string{} |
| 228 | + |
| 229 | + refs, err := keyctl.ListKeyring(defaultKeyring) |
| 230 | + if err != nil { |
| 231 | + return nil, err |
| 232 | + } |
| 233 | + |
| 234 | + for _, r := range refs { |
| 235 | + id, _ := r.Get() |
| 236 | + info, _ := id.Info() |
| 237 | + url, _ := base64.URLEncoding.DecodeString(info.Name) |
| 238 | + |
| 239 | + key, _ := keyctl.OpenKeyring(defaultKeyring, info.Name) |
| 240 | + innerRefs, _ := keyctl.ListKeyring(key) |
| 241 | + |
| 242 | + if len(innerRefs) < 1 { |
| 243 | + continue |
| 244 | + } |
| 245 | + k, _ := innerRefs[0].Get() |
| 246 | + i, _ := k.Info() |
| 247 | + resp[string(url)] = i.Name |
| 248 | + } |
| 249 | + return resp, nil |
| 250 | +} |
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