| 1 | package linkstore |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "crypto/hmac" |
| 7 | "database/sql" |
| 8 | "encoding/json" |
| 9 | "errors" |
| 10 | "io" |
| 11 | "time" |
| 12 | |
| 13 | "amadan.net/oficina/home/handoff" |
| 14 | ) |
| 15 | |
| 16 | type flow struct { |
| 17 | PersonBinding string `json:"person_binding"` |
| 18 | Version int `json:"v"` |
| 19 | PersonID int64 `json:"person"` |
| 20 | SessionHash string `json:"session"` |
| 21 | LocalAuth int64 `json:"local_auth"` |
| 22 | Issuer string `json:"issuer"` |
| 23 | NonceHash string `json:"nonce,omitempty"` |
| 24 | Subject string `json:"subject,omitempty"` |
| 25 | HomeAuth int64 `json:"home_auth,omitempty"` |
| 26 | ReturnPath string `json:"return"` |
| 27 | Expires int64 `json:"expires"` |
| 28 | } |
| 29 | |
| 30 | func (s *Store) purpose(stage, id string) string { |
| 31 | return "identity-link/v1/" + stage + "/" + id + "/" + s.origin |
| 32 | } |
| 33 | func (s *Store) put(ctx context.Context, tx *sql.Tx, stage, id string, f flow) error { |
| 34 | raw, err := json.Marshal(f) |
| 35 | if err != nil { |
| 36 | return ErrStorage |
| 37 | } |
| 38 | sealed, err := s.seal.Seal(s.purpose(stage, id), raw) |
| 39 | if err != nil { |
| 40 | return ErrStorage |
| 41 | } |
| 42 | _, err = tx.ExecContext(ctx, "INSERT INTO home_link_flows (id_hash, stage, expires_at, payload) VALUES (?, ?, ?, ?)", id, stage, f.Expires, sealed) |
| 43 | if err != nil { |
| 44 | return ErrStorage |
| 45 | } |
| 46 | return nil |
| 47 | } |
| 48 | |
| 49 | // load deletes a presented row before interpreting it when consume is true. |
| 50 | // Callers commit refusals, so a rejected conflict or mixed-up browser cannot |
| 51 | // reuse its proof. Storage failures roll back and never install a mapping. |
| 52 | func (s *Store) load(ctx context.Context, tx *sql.Tx, stage, id string, high int64, consume bool) (flow, error) { |
| 53 | var raw []byte |
| 54 | var expires int64 |
| 55 | err := tx.QueryRowContext(ctx, "SELECT expires_at, payload FROM home_link_flows WHERE id_hash = ? AND stage = ?", id, stage).Scan(&expires, &raw) |
| 56 | if errors.Is(err, sql.ErrNoRows) { |
| 57 | return flow{}, ErrRefused |
| 58 | } |
| 59 | if err != nil { |
| 60 | return flow{}, ErrStorage |
| 61 | } |
| 62 | if consume { |
| 63 | if _, err := tx.ExecContext(ctx, "DELETE FROM home_link_flows WHERE id_hash = ? AND stage = ?", id, stage); err != nil { |
| 64 | return flow{}, ErrStorage |
| 65 | } |
| 66 | } |
| 67 | if len(raw) > 8192 || expires <= high { |
| 68 | return flow{}, ErrRefused |
| 69 | } |
| 70 | opened, err := s.seal.Open(s.purpose(stage, id), raw) |
| 71 | if err != nil { |
| 72 | return flow{}, ErrRefused |
| 73 | } |
| 74 | var f flow |
| 75 | dec := json.NewDecoder(bytes.NewReader(opened)) |
| 76 | dec.DisallowUnknownFields() |
| 77 | if dec.Decode(&f) != nil || dec.Decode(new(any)) != io.EOF { |
| 78 | return flow{}, ErrRefused |
| 79 | } |
| 80 | if f.Version != 1 || f.Expires != expires || f.Issuer != s.issuer || !handoff.SafePath(f.ReturnPath) { |
| 81 | return flow{}, ErrRefused |
| 82 | } |
| 83 | return f, nil |
| 84 | } |
| 85 | func (s *Store) matches(f flow, local Local, now, high int64) bool { |
| 86 | return validLocal(local, now, high) && f.PersonID == local.PersonID && f.SessionHash == hash(local.SessionToken) && f.LocalAuth == local.AuthTime.Unix() && fresh(f.LocalAuth, now, high) |
| 87 | } |
| 88 | func (s *Store) currentBinding(ctx context.Context, tx *sql.Tx, id int64) (string, error) { |
| 89 | label, err := s.lookup(ctx, tx, id) |
| 90 | if errors.Is(err, sql.ErrNoRows) { |
| 91 | return "", nil |
| 92 | } |
| 93 | if err != nil { |
| 94 | return "", ErrStorage |
| 95 | } |
| 96 | if label == "" { |
| 97 | return "", nil |
| 98 | } |
| 99 | return s.personBinding(id, label), nil |
| 100 | } |
| 101 | |
| 102 | // Start is called only by an explicit same-origin local-account link POST. |
| 103 | // The returned secret belongs in a host-only Secure/HttpOnly/Lax cookie. |
| 104 | func (s *Store) Start(ctx context.Context, local Local, returnPath string, now time.Time) (string, error) { |
| 105 | tx, high, err := s.begin(ctx, now) |
| 106 | if err != nil { |
| 107 | return "", err |
| 108 | } |
| 109 | defer tx.Rollback() |
| 110 | if err = sweep(ctx, tx, high); err != nil { |
| 111 | return "", err |
| 112 | } |
| 113 | if !validLocal(local, now.Unix(), high) { |
| 114 | return "", refuse(tx) |
| 115 | } |
| 116 | binding, err := s.currentBinding(ctx, tx, local.PersonID) |
| 117 | if err != nil { |
| 118 | return "", err |
| 119 | } |
| 120 | if binding == "" { |
| 121 | return "", refuse(tx) |
| 122 | } |
| 123 | var count int |
| 124 | if err := tx.QueryRowContext(ctx, "SELECT COUNT(*) FROM home_link_flows").Scan(&count); err != nil { |
| 125 | return "", ErrStorage |
| 126 | } |
| 127 | if count >= maxFlows { |
| 128 | return "", refuse(tx) |
| 129 | } |
| 130 | secret, err := newSecret() |
| 131 | if err != nil { |
| 132 | return "", err |
| 133 | } |
| 134 | expires := min(now.Unix()+maxAge, local.AuthTime.Unix()+maxAge) |
| 135 | if expires <= high { |
| 136 | return "", refuse(tx) |
| 137 | } |
| 138 | f := flow{PersonBinding: binding, Version: 1, PersonID: local.PersonID, SessionHash: hash(local.SessionToken), LocalAuth: local.AuthTime.Unix(), Issuer: s.issuer, ReturnPath: safePath(returnPath), Expires: expires} |
| 139 | if err := s.put(ctx, tx, "init", hash(secret), f); err != nil { |
| 140 | return "", err |
| 141 | } |
| 142 | if err := commit(tx); err != nil { |
| 143 | return "", err |
| 144 | } |
| 145 | return secret, nil |
| 146 | } |
| 147 | |
| 148 | // BindNonce is the shared consumer's start hook. It accepts one generated |
| 149 | // nonce exactly once, before that consumer sets its cookie or redirects. |
| 150 | func (s *Store) BindNonce(ctx context.Context, secret string, local Local, nonce string, now time.Time) error { |
| 151 | id, ok := secretHash(secret) |
| 152 | if !ok { |
| 153 | return ErrRefused |
| 154 | } |
| 155 | tx, high, err := s.begin(ctx, now) |
| 156 | if err != nil { |
| 157 | return err |
| 158 | } |
| 159 | defer tx.Rollback() |
| 160 | f, err := s.load(ctx, tx, "init", id, high, true) |
| 161 | if errors.Is(err, ErrRefused) { |
| 162 | return refuse(tx) |
| 163 | } |
| 164 | if err != nil { |
| 165 | return err |
| 166 | } |
| 167 | if !s.matches(f, local, now.Unix(), high) || !handoff.ValidNonce(nonce) || f.NonceHash != "" { |
| 168 | return refuse(tx) |
| 169 | } |
| 170 | binding, err := s.currentBinding(ctx, tx, local.PersonID) |
| 171 | if err != nil { |
| 172 | return err |
| 173 | } |
| 174 | if binding == "" || !hmac.Equal([]byte(binding), []byte(f.PersonBinding)) { |
| 175 | return refuse(tx) |
| 176 | } |
| 177 | f.NonceHash = hash(nonce) |
| 178 | if err := s.put(ctx, tx, "init", id, f); err != nil { |
| 179 | return err |
| 180 | } |
| 181 | return commit(tx) |
| 182 | } |
| 183 | |
| 184 | // Complete consumes the initiation after the shared consumer has consumed and |
| 185 | // verified the Home assertion. It keeps the local Docs session intact. |
| 186 | func (s *Store) Complete(ctx context.Context, secret string, local Local, home Home, now time.Time) (string, error) { |
| 187 | id, ok := secretHash(secret) |
| 188 | if !ok { |
| 189 | return "", ErrRefused |
| 190 | } |
| 191 | tx, high, err := s.begin(ctx, now) |
| 192 | if err != nil { |
| 193 | return "", err |
| 194 | } |
| 195 | defer tx.Rollback() |
| 196 | f, err := s.load(ctx, tx, "init", id, high, true) |
| 197 | if errors.Is(err, ErrRefused) { |
| 198 | return "", refuse(tx) |
| 199 | } |
| 200 | if err != nil { |
| 201 | return "", err |
| 202 | } |
| 203 | if !s.matches(f, local, now.Unix(), high) || !handoff.ValidNonce(home.Nonce) || f.NonceHash != hash(home.Nonce) || home.Issuer != s.issuer || !validSubject(home.Subject) || !fresh(home.AuthTime.Unix(), now.Unix(), high) { |
| 204 | return "", refuse(tx) |
| 205 | } |
| 206 | binding, err := s.currentBinding(ctx, tx, local.PersonID) |
| 207 | if err != nil { |
| 208 | return "", err |
| 209 | } |
| 210 | if binding == "" || !hmac.Equal([]byte(binding), []byte(f.PersonBinding)) { |
| 211 | return "", refuse(tx) |
| 212 | } |
| 213 | pending, err := newSecret() |
| 214 | if err != nil { |
| 215 | return "", err |
| 216 | } |
| 217 | f.Subject, f.HomeAuth = home.Subject, home.AuthTime.Unix() |
| 218 | f.Expires = min(f.Expires, f.HomeAuth+maxAge) |
| 219 | if f.Expires <= high { |
| 220 | return "", refuse(tx) |
| 221 | } |
| 222 | if err := s.put(ctx, tx, "pending", hash(pending), f); err != nil { |
| 223 | return "", err |
| 224 | } |
| 225 | if err := commit(tx); err != nil { |
| 226 | return "", err |
| 227 | } |
| 228 | return pending, nil |
| 229 | } |
| 230 | |
| 231 | func validPending(f flow, now, high int64) bool { |
| 232 | return f.NonceHash != "" && validSubject(f.Subject) && fresh(f.HomeAuth, now, high) |
| 233 | } |
| 234 | func pendingView(f flow) Pending { |
| 235 | return Pending{PersonID: f.PersonID, ReturnPath: f.ReturnPath, HomeAuthTime: time.Unix(f.HomeAuth, 0)} |
| 236 | } |
| 237 | |
| 238 | // Pending reads a still-valid continuation for its current local session. |
| 239 | // Invalid presented state is consumed; reading valid state creates no link. |
| 240 | func (s *Store) Pending(ctx context.Context, secret string, local Local, now time.Time) (Pending, error) { |
| 241 | id, ok := secretHash(secret) |
| 242 | if !ok { |
| 243 | return Pending{}, ErrRefused |
| 244 | } |
| 245 | tx, high, err := s.begin(ctx, now) |
| 246 | if err != nil { |
| 247 | return Pending{}, err |
| 248 | } |
| 249 | defer tx.Rollback() |
| 250 | f, err := s.load(ctx, tx, "pending", id, high, true) |
| 251 | if errors.Is(err, ErrRefused) { |
| 252 | return Pending{}, refuse(tx) |
| 253 | } |
| 254 | if err != nil { |
| 255 | return Pending{}, err |
| 256 | } |
| 257 | if !s.matches(f, local, now.Unix(), high) || !validPending(f, now.Unix(), high) { |
| 258 | return Pending{}, refuse(tx) |
| 259 | } |
| 260 | binding, err := s.currentBinding(ctx, tx, local.PersonID) |
| 261 | if err != nil { |
| 262 | return Pending{}, err |
| 263 | } |
| 264 | if binding == "" || !hmac.Equal([]byte(binding), []byte(f.PersonBinding)) { |
| 265 | return Pending{}, refuse(tx) |
| 266 | } |
| 267 | if err := s.put(ctx, tx, "pending", id, f); err != nil { |
| 268 | return Pending{}, err |
| 269 | } |
| 270 | if err := commit(tx); err != nil { |
| 271 | return Pending{}, err |
| 272 | } |
| 273 | return pendingView(f), nil |
| 274 | } |
| 275 | |
| 276 | // Confirm requires an explicit same-origin POST. The proof deletion and unique |
| 277 | // mapping write commit together. A separate proof for the same mapping is |
| 278 | // idempotent; a reused cookie or conflicting mapping is consumed and refused. |
| 279 | func (s *Store) Confirm(ctx context.Context, secret string, local Local, now time.Time) (Pending, error) { |
| 280 | id, ok := secretHash(secret) |
| 281 | if !ok { |
| 282 | return Pending{}, ErrRefused |
| 283 | } |
| 284 | tx, high, err := s.begin(ctx, now) |
| 285 | if err != nil { |
| 286 | return Pending{}, err |
| 287 | } |
| 288 | defer tx.Rollback() |
| 289 | f, err := s.load(ctx, tx, "pending", id, high, true) |
| 290 | if errors.Is(err, ErrRefused) { |
| 291 | return Pending{}, refuse(tx) |
| 292 | } |
| 293 | if err != nil { |
| 294 | return Pending{}, err |
| 295 | } |
| 296 | if !s.matches(f, local, now.Unix(), high) || !validPending(f, now.Unix(), high) { |
| 297 | return Pending{}, refuse(tx) |
| 298 | } |
| 299 | binding, err := s.currentBinding(ctx, tx, local.PersonID) |
| 300 | if err != nil { |
| 301 | return Pending{}, err |
| 302 | } |
| 303 | if binding == "" || !hmac.Equal([]byte(binding), []byte(f.PersonBinding)) { |
| 304 | return Pending{}, refuse(tx) |
| 305 | } |
| 306 | _, err = tx.ExecContext(ctx, "INSERT INTO home_identity_links (issuer, subject, person_id, person_binding) VALUES (?, ?, ?, ?) ON CONFLICT DO NOTHING", s.issuer, f.Subject, f.PersonID, f.PersonBinding) |
| 307 | if err != nil { |
| 308 | return Pending{}, ErrStorage |
| 309 | } |
| 310 | var person int64 |
| 311 | var storedBinding string |
| 312 | err = tx.QueryRowContext(ctx, "SELECT person_id, person_binding FROM home_identity_links WHERE issuer = ? AND subject = ?", s.issuer, f.Subject).Scan(&person, &storedBinding) |
| 313 | if errors.Is(err, sql.ErrNoRows) { |
| 314 | return Pending{}, refuse(tx) |
| 315 | } |
| 316 | if err != nil { |
| 317 | return Pending{}, ErrStorage |
| 318 | } |
| 319 | if person != f.PersonID || !hmac.Equal([]byte(storedBinding), []byte(f.PersonBinding)) { |
| 320 | return Pending{}, refuse(tx) |
| 321 | } |
| 322 | if err := commit(tx); err != nil { |
| 323 | return Pending{}, err |
| 324 | } |
| 325 | return pendingView(f), nil |
| 326 | } |
| 327 | |
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