package auth import ( "database/sql" "errors" "fmt" _ "github.com/mattn/go-sqlite3" // SQLite driver "golang.org/x/crypto/bcrypt" "strings" ) const ( bcryptCost = 11 intentionalSlowDownHash = "$2a$11$eX15DeF27FwAgXt9wqJF0uAUMz74XywJcGBH3kP93pzKYv6ATk2ka" // Cost should match bcryptCost ) // Auther-related queries const ( createAuthTablesQueries = ` BEGIN; CREATE TABLE IF NOT EXISTS user ( user TEXT NOT NULL PRIMARY KEY, pass TEXT NOT NULL, role TEXT NOT NULL ); CREATE TABLE IF NOT EXISTS access ( user TEXT NOT NULL, topic TEXT NOT NULL, read INT NOT NULL, write INT NOT NULL, PRIMARY KEY (topic, user) ); CREATE TABLE IF NOT EXISTS schemaVersion ( id INT PRIMARY KEY, version INT NOT NULL ); COMMIT; ` selectUserQuery = `SELECT pass, role FROM user WHERE user = ?` selectTopicPermsQuery = ` SELECT read, write FROM access WHERE user IN ('*', ?) AND ? LIKE topic ORDER BY user DESC ` ) // Manager-related queries const ( insertUserQuery = `INSERT INTO user (user, pass, role) VALUES (?, ?, ?)` selectUsernamesQuery = `SELECT user FROM user ORDER BY role, user` updateUserPassQuery = `UPDATE user SET pass = ? WHERE user = ?` updateUserRoleQuery = `UPDATE user SET role = ? WHERE user = ?` deleteUserQuery = `DELETE FROM user WHERE user = ?` upsertUserAccessQuery = ` INSERT INTO access (user, topic, read, write) VALUES (?, ?, ?, ?) ON CONFLICT (user, topic) DO UPDATE SET read=excluded.read, write=excluded.write ` selectUserAccessQuery = `SELECT topic, read, write FROM access WHERE user = ?` deleteAllAccessQuery = `DELETE FROM access` deleteUserAccessQuery = `DELETE FROM access WHERE user = ?` deleteTopicAccessQuery = `DELETE FROM access WHERE user = ? AND topic = ?` ) // Schema management queries const ( currentSchemaVersion = 1 insertSchemaVersion = `INSERT INTO schemaVersion VALUES (1, ?)` selectSchemaVersionQuery = `SELECT version FROM schemaVersion WHERE id = 1` ) // SQLiteAuth is an implementation of Auther and Manager. It stores users and access control list // in a SQLite database. type SQLiteAuth struct { db *sql.DB defaultRead bool defaultWrite bool } var _ Auther = (*SQLiteAuth)(nil) var _ Manager = (*SQLiteAuth)(nil) // NewSQLiteAuth creates a new SQLiteAuth instance func NewSQLiteAuth(filename string, defaultRead, defaultWrite bool) (*SQLiteAuth, error) { db, err := sql.Open("sqlite3", filename) if err != nil { return nil, err } if err := setupAuthDB(db); err != nil { return nil, err } return &SQLiteAuth{ db: db, defaultRead: defaultRead, defaultWrite: defaultWrite, }, nil } // Authenticate checks username and password and returns a user if correct. The method // returns in constant-ish time, regardless of whether the user exists or the password is // correct or incorrect. func (a *SQLiteAuth) Authenticate(username, password string) (*User, error) { if username == Everyone { return nil, ErrUnauthenticated } user, err := a.User(username) if err != nil { bcrypt.CompareHashAndPassword([]byte(intentionalSlowDownHash), []byte("intentional slow-down to avoid timing attacks")) return nil, ErrUnauthenticated } if err := bcrypt.CompareHashAndPassword([]byte(user.Hash), []byte(password)); err != nil { return nil, ErrUnauthenticated } return user, nil } // Authorize returns nil if the given user has access to the given topic using the desired // permission. The user param may be nil to signal an anonymous user. func (a *SQLiteAuth) Authorize(user *User, topic string, perm Permission) error { if user != nil && user.Role == RoleAdmin { return nil // Admin can do everything } username := Everyone if user != nil { username = user.Name } // Select the read/write permissions for this user/topic combo. The query may return two // rows (one for everyone, and one for the user), but prioritizes the user. The value for // user.Name may be empty (= everyone). rows, err := a.db.Query(selectTopicPermsQuery, username, topic) if err != nil { return err } defer rows.Close() if !rows.Next() { return a.resolvePerms(a.defaultRead, a.defaultWrite, perm) } var read, write bool if err := rows.Scan(&read, &write); err != nil { return err } else if err := rows.Err(); err != nil { return err } return a.resolvePerms(read, write, perm) } func (a *SQLiteAuth) resolvePerms(read, write bool, perm Permission) error { if perm == PermissionRead && read { return nil } else if perm == PermissionWrite && write { return nil } return ErrUnauthorized } // AddUser adds a user with the given username, password and role. The password should be hashed // before it is stored in a persistence layer. func (a *SQLiteAuth) AddUser(username, password string, role Role) error { if !AllowedUsername(username) || !AllowedRole(role) { return ErrInvalidArgument } hash, err := bcrypt.GenerateFromPassword([]byte(password), bcryptCost) if err != nil { return err } if _, err = a.db.Exec(insertUserQuery, username, hash, role); err != nil { return err } return nil } // RemoveUser deletes the user with the given username. The function returns nil on success, even // if the user did not exist in the first place. func (a *SQLiteAuth) RemoveUser(username string) error { if !AllowedUsername(username) { return ErrInvalidArgument } if _, err := a.db.Exec(deleteUserQuery, username); err != nil { return err } if _, err := a.db.Exec(deleteUserAccessQuery, username); err != nil { return err } return nil } // Users returns a list of users. It always also returns the Everyone user ("*"). func (a *SQLiteAuth) Users() ([]*User, error) { rows, err := a.db.Query(selectUsernamesQuery) if err != nil { return nil, err } defer rows.Close() usernames := make([]string, 0) for rows.Next() { var username string if err := rows.Scan(&username); err != nil { return nil, err } else if err := rows.Err(); err != nil { return nil, err } usernames = append(usernames, username) } rows.Close() users := make([]*User, 0) for _, username := range usernames { user, err := a.User(username) if err != nil { return nil, err } users = append(users, user) } everyone, err := a.everyoneUser() if err != nil { return nil, err } users = append(users, everyone) return users, nil } // User returns the user with the given username if it exists, or ErrNotFound otherwise. // You may also pass Everyone to retrieve the anonymous user and its Grant list. func (a *SQLiteAuth) User(username string) (*User, error) { if username == Everyone { return a.everyoneUser() } rows, err := a.db.Query(selectUserQuery, username) if err != nil { return nil, err } defer rows.Close() var hash, role string if !rows.Next() { return nil, ErrNotFound } if err := rows.Scan(&hash, &role); err != nil { return nil, err } else if err := rows.Err(); err != nil { return nil, err } grants, err := a.readGrants(username) if err != nil { return nil, err } return &User{ Name: username, Hash: hash, Role: Role(role), Grants: grants, }, nil } func (a *SQLiteAuth) everyoneUser() (*User, error) { grants, err := a.readGrants(Everyone) if err != nil { return nil, err } return &User{ Name: Everyone, Hash: "", Role: RoleAnonymous, Grants: grants, }, nil } func (a *SQLiteAuth) readGrants(username string) ([]Grant, error) { rows, err := a.db.Query(selectUserAccessQuery, username) if err != nil { return nil, err } defer rows.Close() grants := make([]Grant, 0) for rows.Next() { var topic string var read, write bool if err := rows.Scan(&topic, &read, &write); err != nil { return nil, err } else if err := rows.Err(); err != nil { return nil, err } grants = append(grants, Grant{ TopicPattern: fromSQLWildcard(topic), AllowRead: read, AllowWrite: write, }) } return grants, nil } // ChangePassword changes a user's password func (a *SQLiteAuth) ChangePassword(username, password string) error { hash, err := bcrypt.GenerateFromPassword([]byte(password), bcryptCost) if err != nil { return err } if _, err := a.db.Exec(updateUserPassQuery, hash, username); err != nil { return err } return nil } // ChangeRole changes a user's role. When a role is changed from RoleUser to RoleAdmin, // all existing access control entries (Grant) are removed, since they are no longer needed. func (a *SQLiteAuth) ChangeRole(username string, role Role) error { if !AllowedUsername(username) || !AllowedRole(role) { return ErrInvalidArgument } if _, err := a.db.Exec(updateUserRoleQuery, string(role), username); err != nil { return err } if role == RoleAdmin { if _, err := a.db.Exec(deleteUserAccessQuery, username); err != nil { return err } } return nil } // AllowAccess adds or updates an entry in th access control list for a specific user. It controls // read/write access to a topic. The parameter topicPattern may include wildcards (*). func (a *SQLiteAuth) AllowAccess(username string, topicPattern string, read bool, write bool) error { if (!AllowedUsername(username) && username != Everyone) || !AllowedTopicPattern(topicPattern) { return ErrInvalidArgument } if _, err := a.db.Exec(upsertUserAccessQuery, username, toSQLWildcard(topicPattern), read, write); err != nil { return err } return nil } // ResetAccess removes an access control list entry for a specific username/topic, or (if topic is // empty) for an entire user. The parameter topicPattern may include wildcards (*). func (a *SQLiteAuth) ResetAccess(username string, topicPattern string) error { if !AllowedUsername(username) && username != Everyone && username != "" { return ErrInvalidArgument } else if !AllowedTopicPattern(topicPattern) && topicPattern != "" { return ErrInvalidArgument } if username == "" && topicPattern == "" { _, err := a.db.Exec(deleteAllAccessQuery, username) return err } else if topicPattern == "" { _, err := a.db.Exec(deleteUserAccessQuery, username) return err } _, err := a.db.Exec(deleteTopicAccessQuery, username, toSQLWildcard(topicPattern)) return err } // DefaultAccess returns the default read/write access if no access control entry matches func (a *SQLiteAuth) DefaultAccess() (read bool, write bool) { return a.defaultRead, a.defaultWrite } func toSQLWildcard(s string) string { return strings.ReplaceAll(s, "*", "%") } func fromSQLWildcard(s string) string { return strings.ReplaceAll(s, "%", "*") } func setupAuthDB(db *sql.DB) error { // If 'schemaVersion' table does not exist, this must be a new database rowsSV, err := db.Query(selectSchemaVersionQuery) if err != nil { return setupNewAuthDB(db) } defer rowsSV.Close() // If 'schemaVersion' table exists, read version and potentially upgrade schemaVersion := 0 if !rowsSV.Next() { return errors.New("cannot determine schema version: database file may be corrupt") } if err := rowsSV.Scan(&schemaVersion); err != nil { return err } rowsSV.Close() // Do migrations if schemaVersion == currentSchemaVersion { return nil } return fmt.Errorf("unexpected schema version found: %d", schemaVersion) } func setupNewAuthDB(db *sql.DB) error { if _, err := db.Exec(createAuthTablesQueries); err != nil { return err } if _, err := db.Exec(insertSchemaVersion, currentSchemaVersion); err != nil { return err } return nil }