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b5bf1913d

Denys Vlasenko
Denys Vlasenko
2017-01-23
SUCCESS Duration: 254s

Subject

tls: send EMPTY_RENEGOTIATION_INFO_SCSV in our client hello

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

networking/tls.c +86 -26
networking/tls.c+86 -26
@@ -22,6 +22,16 @@
#define TLS_DEBUG_HASH 0
#define TLS_DEBUG_DER 0
#define TLS_DEBUG_FIXED_SECRETS 0
+#if 0
+# define dump_raw_out(...) dump_hex(__VA_ARGS__)
+#else
+# define dump_raw_out(...) ((void)0)
+#endif
+#if 0
+# define dump_raw_in(...) dump_hex(__VA_ARGS__)
+#else
+# define dump_raw_in(...) ((void)0)
+#endif
#if TLS_DEBUG
# define dbg(...) fprintf(stderr, __VA_ARGS__)
@@ -35,18 +45,6 @@
# define dbg_der(...) ((void)0)
#endif
-#if 0
-# define dump_raw_out(...) dump_hex(__VA_ARGS__)
-#else
-# define dump_raw_out(...) ((void)0)
-#endif
-
-#if 0
-# define dump_raw_in(...) dump_hex(__VA_ARGS__)
-#else
-# define dump_raw_in(...) ((void)0)
-#endif
-
#define RECORD_TYPE_CHANGE_CIPHER_SPEC 20
#define RECORD_TYPE_ALERT 21
#define RECORD_TYPE_HANDSHAKE 22
@@ -154,8 +152,18 @@
// works against "openssl s_server -cipher NULL"
// and against wolfssl-3.9.10-stable/examples/server/server.c:
//#define CIPHER_ID TLS_RSA_WITH_NULL_SHA256 // for testing (does everything except encrypting)
+
// works against wolfssl-3.9.10-stable/examples/server/server.c
-#define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // ok, no SERVER_KEY_EXCHANGE
+// works for kernel.org
+// does not work for cdn.kernel.org (e.g. downloading an actual tarball, not a web page)
+// getting alert 40 "handshake failure" at once
+// with GNU Wget 1.18, they agree on TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (0xC02F) cipher
+// fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES256-SHA256
+// fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES256-GCM-SHA384
+// fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-SHA256
+// ok: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-GCM-SHA256
+// ok: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-SHA
+#define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // no SERVER_KEY_EXCHANGE from peer
enum {
RSA_PREMASTER_SIZE = 48,
@@ -445,6 +453,18 @@ static void prf_hmac_sha256(
#undef SEED
}
+static void bad_record_die(tls_state_t *tls, const char *expected, int len)
+{
+ bb_error_msg_and_die("got bad TLS record (len:%d) while expecting %s", len, expected);
+ if (len > 0) {
+ uint8_t *p = tls->inbuf;
+ while (len > 0)
+ fprintf(stderr, " %02x", *p++);
+ fputc('\n', stderr);
+ }
+ xfunc_die();
+}
+
static void tls_error_die(tls_state_t *tls)
{
dump_tls_record(tls->inbuf, tls->ofs_to_buffered + tls->buffered_size);
@@ -671,6 +691,18 @@ static int tls_has_buffered_record(tls_state_t *tls)
return rec_size;
}
+static const char *alert_text(int code)
+{
+ switch (code) {
+ case 20: return "bad MAC";
+ case 50: return "decode error";
+ case 51: return "decrypt error";
+ case 40: return "handshake failure";
+ case 112: return "unrecognized name";
+ }
+ return itoa(code);
+}
+
static int tls_xread_record(tls_state_t *tls)
{
struct record_hdr *xhdr;
@@ -780,16 +812,28 @@ static int tls_xread_record(tls_state_t *tls)
if (xhdr->type == RECORD_TYPE_ALERT && sz >= 2) {
uint8_t *p = tls->inbuf + RECHDR_LEN;
dbg("ALERT size:%d level:%d description:%d\n", sz, p[0], p[1]);
+ if (p[0] == 2) { /* fatal */
+ bb_error_msg_and_die("TLS %s from peer (alert code %d): %s",
+ "error",
+ p[1], alert_text(p[1])
+ );
+ }
if (p[0] == 1) { /* warning */
if (p[1] == 0) { /* "close_notify" warning: it's EOF */
dbg("EOF (TLS encoded) from peer\n");
sz = 0;
goto end;
}
+//This possibly needs to be cached and shown only if
+//a fatal alert follows
+// bb_error_msg("TLS %s from peer (alert code %d): %s",
+// "warning",
+// p[1], alert_text(p[1])
+// );
/* discard it, get next record */
goto again;
}
- /* p[0] == 1: fatal error, others: not defined in protocol */
+ /* p[0] not 1 or 2: not defined in protocol */
sz = 0;
goto end;
}
@@ -1031,7 +1075,7 @@ static int tls_xread_handshake_block(tls_state_t *tls, int min_len)
|| xhdr->proto_maj != TLS_MAJ
|| xhdr->proto_min != TLS_MIN
) {
- tls_error_die(tls);
+ bad_record_die(tls, "handshake record", len);
}
dbg("got HANDSHAKE\n");
return len;
@@ -1051,7 +1095,6 @@ static ALWAYS_INLINE void fill_handshake_record_hdr(void *buf, unsigned type, un
h->len24_lo = len & 0xff;
}
-//TODO: implement RFC 5746 (Renegotiation Indication Extension) - some servers will refuse to work with us otherwise
static void send_client_hello(tls_state_t *tls, const char *sni)
{
struct client_hello {
@@ -1062,18 +1105,27 @@ static void send_client_hello(tls_state_t *tls, const char *sni)
uint8_t session_id_len;
/* uint8_t session_id[]; */
uint8_t cipherid_len16_hi, cipherid_len16_lo;
- uint8_t cipherid[2 * 1]; /* actually variable */
+ uint8_t cipherid[2 * 2]; /* actually variable */
uint8_t comprtypes_len;
uint8_t comprtypes[1]; /* actually variable */
/* Extensions (SNI shown):
* hi,lo // len of all extensions
- * 0x00,0x00 // extension_type: "Server Name"
- * 0x00,0x0e // list len (there can be more than one SNI)
- * 0x00,0x0c // len of 1st Server Name Indication
- * 0x00 // name type: host_name
- * 0x00,0x09 // name len
+ * 00,00 // extension_type: "Server Name"
+ * 00,0e // list len (there can be more than one SNI)
+ * 00,0c // len of 1st Server Name Indication
+ * 00 // name type: host_name
+ * 00,09 // name len
* "localhost" // name
*/
+// GNU Wget 1.18 to cdn.kernel.org sends these extensions:
+// 0055
+// 0005 0005 0100000000 - status_request
+// 0000 0013 0011 00 000e 63646e 2e 6b65726e656c 2e 6f7267 - server_name
+// ff01 0001 00 - renegotiation_info
+// 0023 0000 - session_ticket
+// 000a 0008 0006001700180019 - supported_groups
+// 000b 0002 0100 - ec_point_formats
+// 000d 0016 00140401040305010503060106030301030302010203 - signature_algorithms
};
struct client_hello *record;
int len;
@@ -1084,6 +1136,7 @@ static void send_client_hello(tls_state_t *tls, const char *sni)
len += 11 + strlen(sni);
record = tls_get_outbuf(tls, len);
memset(record, 0, len);
+
fill_handshake_record_hdr(record, HANDSHAKE_CLIENT_HELLO, len);
record->proto_maj = TLS_MAJ; /* the "requested" version of the protocol, */
record->proto_min = TLS_MIN; /* can be higher than one in record headers */
@@ -1092,10 +1145,16 @@ static void send_client_hello(tls_state_t *tls, const char *sni)
memset(record->rand32, 0x11, sizeof(record->rand32));
memcpy(tls->hsd->client_and_server_rand32, record->rand32, sizeof(record->rand32));
/* record->session_id_len = 0; - already is */
+
/* record->cipherid_len16_hi = 0; */
- record->cipherid_len16_lo = 2 * 1;
- record->cipherid[0] = CIPHER_ID >> 8;
+ record->cipherid_len16_lo = 2 * 2;
+ if ((CIPHER_ID >> 8) != 0)
+ record->cipherid[0] = CIPHER_ID >> 8;
record->cipherid[1] = CIPHER_ID & 0xff;
+ /* RFC 5746 Renegotiation Indication Extension - some servers will refuse to work with us otherwise */
+ /*record->cipherid[2] = TLS_EMPTY_RENEGOTIATION_INFO_SCSV >> 8; - zero */
+ record->cipherid[3] = TLS_EMPTY_RENEGOTIATION_INFO_SCSV & 0xff;
+
record->comprtypes_len = 1;
/* record->comprtypes[0] = 0; */
@@ -1136,8 +1195,9 @@ static void get_server_hello(tls_state_t *tls)
struct server_hello *hp;
uint8_t *cipherid;
+ int len;
- tls_xread_handshake_block(tls, 74);
+ len = tls_xread_handshake_block(tls, 74);
hp = (void*)tls->inbuf;
// 74 bytes:
@@ -1150,7 +1210,7 @@ static void get_server_hello(tls_state_t *tls)
|| hp->proto_maj != TLS_MAJ
|| hp->proto_min != TLS_MIN
) {
- tls_error_die(tls);
+ bad_record_die(tls, "'server hello'", len);
}
cipherid = &hp->cipherid_hi;