9772e55c73
Multi-user from the first migration, as planned. - auth: argon2id password hashing (PHC encoded, parameters travel with the hash), opaque session tokens stored only as SHA-256, login rate limiting, and account enumeration resistance (unknown user hashes anyway) - sessions: cookie or Bearer auth, HttpOnly + SameSite=Lax, revocation on password change - grants: library_grants is the single access-control chokepoint. Admins see every library; everyone else sees exactly their can_read grants - bootstrap: VELLUM_ADMIN_USER/PASSWORD create the first admin only on an empty database. No default password is ever invented. - httpapi: mounts modules on a shared mux, session middleware innermost - httpx: shared JSON helpers, strict body decoding Gate: two users see different libraries. Tests cover that, plus session expiry, token-at-rest, grant upsert, and the full login/me/logout flow.
106 lines
3.5 KiB
Go
106 lines
3.5 KiB
Go
// Package auth implements identity: password hashing, sessions, per-library
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// grants, and the middleware that turns a cookie into a current user.
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//
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// Nothing outside this package may inspect a password or a raw session token.
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package auth
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import (
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"crypto/rand"
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"crypto/subtle"
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"encoding/base64"
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"errors"
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"fmt"
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"strings"
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"golang.org/x/crypto/argon2"
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)
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// Argon2id parameters. These are the OWASP-recommended baseline for
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// interactive logins (memory cost is the dominant factor). They are encoded
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// into every hash, so changing them here does not invalidate old passwords —
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// existing hashes keep verifying with their own stored parameters.
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const (
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argonTime = 2
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argonMemory = 64 * 1024 // KiB, i.e. 64 MiB
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argonThreads = 4
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argonKeyLen = 32
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argonSaltLen = 16
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)
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var (
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// ErrInvalidHash means a stored password hash is not in the PHC format
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// this package writes. It indicates database corruption, not a bad login.
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ErrInvalidHash = errors.New("auth: password hash is not in PHC format")
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// ErrIncompatibleVersion means the hash was made by a newer argon2 version.
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ErrIncompatibleVersion = errors.New("auth: incompatible argon2 version")
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)
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// HashPassword derives an argon2id hash and returns it as a PHC string:
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//
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// $argon2id$v=19$m=65536,t=2,p=4$<salt>$<hash>
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//
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// The parameters travel with the hash, so verification never needs them passed
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// in and parameter changes are backward compatible.
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func HashPassword(password string) (string, error) {
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salt := make([]byte, argonSaltLen)
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if _, err := rand.Read(salt); err != nil {
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return "", fmt.Errorf("auth: read salt: %w", err)
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}
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key := argon2.IDKey([]byte(password), salt, argonTime, argonMemory, argonThreads, argonKeyLen)
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return fmt.Sprintf("$argon2id$v=%d$m=%d,t=%d,p=%d$%s$%s",
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argon2.Version, argonMemory, argonTime, argonThreads,
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base64.RawStdEncoding.EncodeToString(salt),
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base64.RawStdEncoding.EncodeToString(key),
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), nil
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}
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// VerifyPassword reports whether password matches the PHC-encoded hash.
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// It always performs the full derivation, so a malformed hash and a wrong
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// password cost the same — there is no timing oracle for "user exists".
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func VerifyPassword(password, encoded string) (bool, error) {
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salt, want, params, err := decodeHash(encoded)
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if err != nil {
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return false, err
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}
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got := argon2.IDKey([]byte(password), salt, params.time, params.memory, params.threads, uint32(len(want)))
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return subtle.ConstantTimeCompare(got, want) == 1, nil
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}
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type argonParams struct {
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time uint32
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memory uint32
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threads uint8
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}
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func decodeHash(encoded string) (salt, hash []byte, p argonParams, err error) {
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parts := strings.Split(encoded, "$")
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// Leading empty field from the leading '$' gives 6 fields.
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if len(parts) != 6 || parts[0] != "" || parts[1] != "argon2id" {
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return nil, nil, p, ErrInvalidHash
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}
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var version int
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if _, err := fmt.Sscanf(parts[2], "v=%d", &version); err != nil {
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return nil, nil, p, ErrInvalidHash
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}
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if version != argon2.Version {
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return nil, nil, p, ErrIncompatibleVersion
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}
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if _, err := fmt.Sscanf(parts[3], "m=%d,t=%d,p=%d", &p.memory, &p.time, &p.threads); err != nil {
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return nil, nil, p, ErrInvalidHash
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}
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salt, err = base64.RawStdEncoding.Strict().DecodeString(parts[4])
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if err != nil {
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return nil, nil, p, ErrInvalidHash
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}
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hash, err = base64.RawStdEncoding.Strict().DecodeString(parts[5])
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if err != nil {
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return nil, nil, p, ErrInvalidHash
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}
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if len(hash) == 0 || len(salt) == 0 {
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return nil, nil, p, ErrInvalidHash
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}
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return salt, hash, p, nil
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}
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