TUN-5286: Upgrade crypto/ssh package to fix CVE-2020-29652

vendor/golang.org/x/crypto/cryptobyte/asn1.go

@@ -117,6 +117,19 @@ func (b *Builder) AddASN1GeneralizedTime(t time.Time) {
 	})
 }
 
+// AddASN1UTCTime appends a DER-encoded ASN.1 UTCTime.
+func (b *Builder) AddASN1UTCTime(t time.Time) {
+	b.AddASN1(asn1.UTCTime, func(c *Builder) {
+		// As utilized by the X.509 profile, UTCTime can only
+		// represent the years 1950 through 2049.
+		if t.Year() < 1950 || t.Year() >= 2050 {
+			b.err = fmt.Errorf("cryptobyte: cannot represent %v as a UTCTime", t)
+			return
+		}
+		c.AddBytes([]byte(t.Format(defaultUTCTimeFormatStr)))
+	})
+}
+
 // AddASN1BitString appends a DER-encoded ASN.1 BIT STRING. This does not
 // support BIT STRINGs that are not a whole number of bytes.
 func (b *Builder) AddASN1BitString(data []byte) {
@@ -466,6 +479,45 @@ func (s *String) ReadASN1GeneralizedTime(out *time.Time) bool {
 	return true
 }
 
+const defaultUTCTimeFormatStr = "060102150405Z0700"
+
+// ReadASN1UTCTime decodes an ASN.1 UTCTime into out and advances.
+// It reports whether the read was successful.
+func (s *String) ReadASN1UTCTime(out *time.Time) bool {
+	var bytes String
+	if !s.ReadASN1(&bytes, asn1.UTCTime) {
+		return false
+	}
+	t := string(bytes)
+
+	formatStr := defaultUTCTimeFormatStr
+	var err error
+	res, err := time.Parse(formatStr, t)
+	if err != nil {
+		// Fallback to minute precision if we can't parse second
+		// precision. If we are following X.509 or X.690 we shouldn't
+		// support this, but we do.
+		formatStr = "0601021504Z0700"
+		res, err = time.Parse(formatStr, t)
+	}
+	if err != nil {
+		return false
+	}
+
+	if serialized := res.Format(formatStr); serialized != t {
+		return false
+	}
+
+	if res.Year() >= 2050 {
+		// UTCTime interprets the low order digits 50-99 as 1950-99.
+		// This only applies to its use in the X.509 profile.
+		// See https://tools.ietf.org/html/rfc5280#section-4.1.2.5.1
+		res = res.AddDate(-100, 0, 0)
+	}
+	*out = res
+	return true
+}
+
 // ReadASN1BitString decodes an ASN.1 BIT STRING into out and advances.
 // It reports whether the read was successful.
 func (s *String) ReadASN1BitString(out *encoding_asn1.BitString) bool {