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tls: send EMPTY_RENEGOTIATION_INFO_SCSV in our client hello

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Hoped this can make cdn.kernel.org to like us more. Nope.
While at it, made error reporting more useful.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2017-01-23 16:12:17 +01:00
parent 9492da7e63
commit b5bf1913d3
1 changed files with 86 additions and 26 deletions
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112
networking/tls.c
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@ -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;