fix(auth): VerifyPassword валидирует параметры/версию, не паникует на битом хэше

internal/auth/password.go

@@ -5,6 +5,8 @@ import (
 	"crypto/subtle"
 	"encoding/base64"
 	"fmt"
+	"regexp"
+	"strconv"
 	"strings"
 
 	"golang.org/x/crypto/argon2"
@@ -16,8 +18,18 @@ const (
 	argonThreads = 4
 	argonKeyLen  = 32
 	argonSaltLen = 16
+
+	// Upper bounds guard against a corrupted/attacker-controlled
+	// password_hash forcing an oversized argon2 computation (DoS).
+	argonMaxMemoryKiB = 1 << 21 // 2 GiB in KiB
+	argonMaxTime      = 10
+	argonMaxThreads   = 16
 )
 
+// paramsRe strictly matches the "m=<n>,t=<n>,p=<n>" parameter segment,
+// requiring the whole segment to be consumed (no trailing garbage).
+var paramsRe = regexp.MustCompile(`^m=([0-9]+),t=([0-9]+),p=([0-9]+)$`)
+
 func HashPassword(password string) (string, error) {
 	salt := make([]byte, argonSaltLen)
 	if _, err := rand.Read(salt); err != nil {
@@ -34,11 +46,40 @@ func VerifyPassword(encoded, password string) (bool, error) {
 	if len(parts) != 6 || parts[1] != "argon2id" {
 		return false, fmt.Errorf("auth: bad hash format")
 	}
-	var m, t uint32
-	var p uint8
-	if _, err := fmt.Sscanf(parts[3], "m=%d,t=%d,p=%d", &m, &t, &p); err != nil {
-		return false, err
+	if parts[2] != "v=19" {
+		return false, fmt.Errorf("auth: unsupported version")
 	}
+
+	matches := paramsRe.FindStringSubmatch(parts[3])
+	if matches == nil {
+		return false, fmt.Errorf("auth: bad hash format")
+	}
+	m64, err := strconv.ParseUint(matches[1], 10, 32)
+	if err != nil {
+		return false, fmt.Errorf("auth: bad hash format")
+	}
+	t64, err := strconv.ParseUint(matches[2], 10, 32)
+	if err != nil {
+		return false, fmt.Errorf("auth: bad hash format")
+	}
+	p64, err := strconv.ParseUint(matches[3], 10, 8)
+	if err != nil {
+		return false, fmt.Errorf("auth: bad hash format")
+	}
+	m, t, p := uint32(m64), uint32(t64), uint8(p64)
+
+	// argon2.IDKey panics if time<1 ("number of rounds too small") or
+	// threads<1 ("parallelism degree too low"). Reject before calling it.
+	// Minimum memory per argon2 spec is 8*parallelism (in KiB).
+	if t < 1 || p < 1 || m < 8*uint32(p) {
+		return false, fmt.Errorf("auth: bad hash params")
+	}
+	// Upper bounds guard against DoS via inflated parameters in a
+	// corrupted or attacker-controlled stored hash.
+	if m > argonMaxMemoryKiB || t > argonMaxTime || p > argonMaxThreads {
+		return false, fmt.Errorf("auth: bad hash params")
+	}
+
 	salt, err := base64.RawStdEncoding.DecodeString(parts[4])
 	if err != nil {
 		return false, err

internal/auth/password_test.go

@@ -27,3 +27,61 @@ func TestHashNonDeterministic(t *testing.T) {
 		t.Fatal("salt must randomize hash")
 	}
 }
+
+func TestVerifyPasswordBadTimeDoesNotPanic(t *testing.T) {
+	defer func() {
+		if r := recover(); r != nil {
+			t.Fatalf("VerifyPassword panicked: %v", r)
+		}
+	}()
+	encoded := "$argon2id$v=19$m=65536,t=0,p=4$c29tZXNhbHRzb21lc2FsdA$c29tZWhhc2hzb21laGFzaA"
+	ok, err := VerifyPassword(encoded, "anything")
+	if err == nil {
+		t.Fatal("expected error for t=0, got nil")
+	}
+	if ok {
+		t.Fatal("expected ok=false for t=0")
+	}
+}
+
+func TestVerifyPasswordBadThreadsDoesNotPanic(t *testing.T) {
+	defer func() {
+		if r := recover(); r != nil {
+			t.Fatalf("VerifyPassword panicked: %v", r)
+		}
+	}()
+	encoded := "$argon2id$v=19$m=65536,t=1,p=0$c29tZXNhbHRzb21lc2FsdA$c29tZWhhc2hzb21laGFzaA"
+	ok, err := VerifyPassword(encoded, "anything")
+	if err == nil {
+		t.Fatal("expected error for p=0, got nil")
+	}
+	if ok {
+		t.Fatal("expected ok=false for p=0")
+	}
+}
+
+func TestVerifyPasswordUnsupportedVersion(t *testing.T) {
+	encoded := "$argon2id$v=18$m=65536,t=1,p=4$c29tZXNhbHRzb21lc2FsdA$c29tZWhhc2hzb21laGFzaA"
+	ok, err := VerifyPassword(encoded, "anything")
+	if err == nil {
+		t.Fatal("expected error for unsupported version, got nil")
+	}
+	if ok {
+		t.Fatal("expected ok=false for unsupported version")
+	}
+}
+
+func TestVerifyPasswordGarbageFormatDoesNotPanic(t *testing.T) {
+	defer func() {
+		if r := recover(); r != nil {
+			t.Fatalf("VerifyPassword panicked: %v", r)
+		}
+	}()
+	ok, err := VerifyPassword("notahash", "anything")
+	if err == nil {
+		t.Fatal("expected error for garbage format, got nil")
+	}
+	if ok {
+		t.Fatal("expected ok=false for garbage format")
+	}
+}