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tls: address one easy FIXME, tidy up comments

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2017-01-17 18:17:27 +01:00
parent e69d78c038
commit 5d1662ea1c
1 changed files with 71 additions and 67 deletions
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138
networking/tls.c
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@ -262,7 +262,6 @@ static void hash_sha256(uint8_t out[SHA256_OUTSIZE], const void *data, unsigned
sha256_end(&ctx, out);
}
#if TLS_DEBUG >= 2
/* Nondestructively see the current hash value */
static void sha256_peek(sha256_ctx_t *ctx, void *buffer)
{
@ -270,6 +269,7 @@ static void sha256_peek(sha256_ctx_t *ctx, void *buffer)
sha256_end(&ctx_copy, buffer);
}
#if TLS_DEBUG >= 2
static void sha256_hash_dbg(const char *fmt, sha256_ctx_t *ctx, const void *buffer, size_t len)
{
uint8_t h[SHA256_OUTSIZE];
@ -384,7 +384,7 @@ static void hmac_sha256(uint8_t out[SHA256_OUTSIZE], uint8_t *key, unsigned key_
// PRF(secret, label, seed) = P_<hash>(secret, label + seed)
//
// The label is an ASCII string.
static void tls_prf_hmac_sha256(
static void prf_hmac_sha256(
uint8_t *outbuf, unsigned outbuf_size,
uint8_t *secret, unsigned secret_size,
const char *label,
@ -794,6 +794,35 @@ static int xread_tls_handshake_block(tls_state_t *tls, int min_len)
return len;
}
static void fill_handshake_record_hdr(struct record_hdr *xhdr, unsigned len)
{
struct handshake_hdr {
struct record_hdr xhdr;
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
} *h = (void*)xhdr;
h->xhdr.type = RECORD_TYPE_HANDSHAKE;
h->xhdr.proto_maj = TLS_MAJ;
h->xhdr.proto_min = TLS_MIN;
len -= 5;
h->xhdr.len16_hi = len >> 8;
// can be optimized to do one store instead of four:
// uint32_t v = htonl(0x100*(RECORD_TYPE_HANDSHAKE + 0x100*(TLS_MAJ + 0x100*(TLS_MIN))))
// | ((len >> 8) << 24); // little-endian specific, don't use in this form
// *(uint32_t *)xhdr = v;
h->xhdr.len16_lo = len & 0xff;
len -= 4;
h->len24_hi = len >> 16;
h->len24_mid = len >> 8;
h->len24_lo = len & 0xff;
memset(h + 1, 0, len);
}
//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)
{
struct client_hello {
@ -809,33 +838,25 @@ static void send_client_hello(tls_state_t *tls)
uint8_t comprtypes_len;
uint8_t comprtypes[1]; /* actually variable */
};
struct client_hello hello;
struct client_hello record;
memset(&hello, 0, sizeof(hello));
hello.xhdr.type = RECORD_TYPE_HANDSHAKE;
hello.xhdr.proto_maj = TLS_MAJ;
hello.xhdr.proto_min = TLS_MIN;
//zero: hello.xhdr.len16_hi = (sizeof(hello) - sizeof(hello.xhdr)) >> 8;
hello.xhdr.len16_lo = (sizeof(hello) - sizeof(hello.xhdr));
hello.type = HANDSHAKE_CLIENT_HELLO;
//hello.len24_hi = 0;
//zero: hello.len24_mid = (sizeof(hello) - sizeof(hello.xhdr) - 4) >> 8;
hello.len24_lo = (sizeof(hello) - sizeof(hello.xhdr) - 4);
hello.proto_maj = TLS_MAJ; /* the "requested" version of the protocol, */
hello.proto_min = TLS_MIN; /* can be higher than one in record headers */
tls_get_random(hello.rand32, sizeof(hello.rand32));
//hello.session_id_len = 0;
//hello.cipherid_len16_hi = 0;
hello.cipherid_len16_lo = 2 * 1;
hello.cipherid[0] = CIPHER_ID >> 8;
hello.cipherid[1] = CIPHER_ID & 0xff;
hello.comprtypes_len = 1;
//hello.comprtypes[0] = 0;
fill_handshake_record_hdr(&record.xhdr, sizeof(record));
record.type = HANDSHAKE_CLIENT_HELLO;
record.proto_maj = TLS_MAJ; /* the "requested" version of the protocol, */
record.proto_min = TLS_MIN; /* can be higher than one in record headers */
tls_get_random(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[1] = CIPHER_ID & 0xff;
record.comprtypes_len = 1;
/* record.comprtypes[0] = 0; */
//dbg (make it repeatable): memset(hello.rand32, 0x11, sizeof(hello.rand32));
//dbg (make it repeatable): memset(record.rand32, 0x11, sizeof(record.rand32));
dbg(">> HANDSHAKE_CLIENT_HELLO\n");
xwrite_and_hash(tls, &hello, sizeof(hello));
memcpy(tls->client_and_server_rand32, hello.rand32, sizeof(hello.rand32));
xwrite_and_hash(tls, &record, sizeof(record));
memcpy(tls->client_and_server_rand32, record.rand32, sizeof(record.rand32));
}
static void get_server_hello(tls_state_t *tls)
@ -892,7 +913,7 @@ static void get_server_hello(tls_state_t *tls)
tls_error_die(tls);
}
dbg("got SERVER_HELLO\n");
dbg("<< SERVER_HELLO\n");
memcpy(tls->client_and_server_rand32 + 32, hp->rand32, sizeof(hp->rand32));
}
@ -908,7 +929,7 @@ static void get_server_cert(tls_state_t *tls)
certbuf = (void*)(xhdr + 1);
if (certbuf[0] != HANDSHAKE_CERTIFICATE)
tls_error_die(tls);
dbg("got CERTIFICATE\n");
dbg("<< CERTIFICATE\n");
// 4392 bytes:
// 0b 00|11|24 00|11|21 00|05|b0 30|82|05|ac|30|82|04|94|a0|03|02|01|02|02|11|00|9f|85|bf|66|4b|0c|dd|af|ca|50|86|79|50|1b|2b|e4|30|0d...
//Cert len=4388 ChainLen CertLen^ DER encoded X509 starts here. openssl x509 -in FILE -inform DER -noout -text
@ -932,29 +953,22 @@ static void send_client_key_exchange(tls_state_t *tls)
struct record_hdr xhdr;
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
uint8_t keylen16_hi, keylen16_lo; /* exist for RSA, but not for some other key types */
//had a bug when had no keylen: we:
//write(3, "\x16\x03\x03\x01\x84\x10\x00\x01\x80\xXX\xXX\xXX\xXX\xXX\xXX...", 393) = 393
//openssl:
//write to 0xe9a090 [0xf9ac20] (395 bytes => 395 (0x18B))
//0000 - 16 03 03 01 86 10 00 01 -82 01 80 xx xx xx xx xx
/* keylen16 exists for RSA (in TLS, not in SSL), but not for some other key types */
uint8_t keylen16_hi, keylen16_lo;
uint8_t key[4 * 1024]; // size??
};
struct client_key_exchange record;
uint8_t rsa_premaster[SSL_HS_RSA_PREMASTER_SIZE];
int len;
memset(&record, 0, sizeof(record));
record.xhdr.type = RECORD_TYPE_HANDSHAKE;
record.xhdr.proto_maj = TLS_MAJ;
record.xhdr.proto_min = TLS_MIN;
fill_handshake_record_hdr(&record.xhdr, sizeof(record) - sizeof(record.key));
record.type = HANDSHAKE_CLIENT_KEY_EXCHANGE;
tls_get_random(rsa_premaster, sizeof(rsa_premaster));
// RFC 5246
// "Note: The version number in the PreMasterSecret is the version
// offered by the client in the ClientHello.client_version, not the
// version negotiated for the connection."
// RFC 5246
// "Note: The version number in the PreMasterSecret is the version
// offered by the client in the ClientHello.client_version, not the
// version negotiated for the connection."
rsa_premaster[0] = TLS_MAJ;
rsa_premaster[1] = TLS_MIN;
len = psRsaEncryptPub(/*pool:*/ NULL,
@ -963,10 +977,11 @@ static void send_client_key_exchange(tls_state_t *tls)
record.key, sizeof(record.key),
data_param_ignored
);
/* length fields need fixing */
record.keylen16_hi = len >> 8;
record.keylen16_lo = len & 0xff;
len += 2;
//record.len24_hi = 0;
/* record.len24_hi = 0; - already is */
record.len24_mid = len >> 8;
record.len24_lo = len & 0xff;
len += 4;
@ -986,7 +1001,7 @@ static void send_client_key_exchange(tls_state_t *tls)
// [0..47];
// The master secret is always exactly 48 bytes in length. The length
// of the premaster secret will vary depending on key exchange method.
tls_prf_hmac_sha256(
prf_hmac_sha256(
tls->master_secret, sizeof(tls->master_secret),
rsa_premaster, sizeof(rsa_premaster),
"master secret",
@ -1033,7 +1048,7 @@ static void send_client_key_exchange(tls_state_t *tls)
memcpy(&tmp64[0] , &tls->client_and_server_rand32[32], 32);
memcpy(&tmp64[32], &tls->client_and_server_rand32[0] , 32);
tls_prf_hmac_sha256(
prf_hmac_sha256(
tls->client_write_MAC_key, sizeof(tls->client_write_MAC_key),
tls->master_secret, sizeof(tls->master_secret),
"key expansion",
@ -1107,23 +1122,12 @@ static void send_client_finished(tls_state_t *tls)
};
struct client_finished record;
uint8_t handshake_hash[SHA256_OUTSIZE];
sha256_ctx_t ctx;
memset(&record, 0, sizeof(record));
record.xhdr.type = RECORD_TYPE_HANDSHAKE;
record.xhdr.proto_maj = TLS_MAJ;
record.xhdr.proto_min = TLS_MIN;
record.xhdr.len16_hi = (sizeof(record) - sizeof(record.xhdr)) >> 8;
record.xhdr.len16_lo = (sizeof(record) - sizeof(record.xhdr)) & 0xff;
fill_handshake_record_hdr(&record.xhdr, sizeof(record));
record.type = HANDSHAKE_FINISHED;
//record.len24_hi = 0;
record.len24_mid = (sizeof(record) - sizeof(record.xhdr) - 4) >> 8;
record.len24_lo = (sizeof(record) - sizeof(record.xhdr) - 4) & 0xff;
//FIXME ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this code is repeatable
ctx = tls->handshake_sha256_ctx; /* struct copy */
sha256_end(&ctx, handshake_hash);
tls_prf_hmac_sha256(record.prf_result, sizeof(record.prf_result),
sha256_peek(&tls->handshake_sha256_ctx, handshake_hash);
prf_hmac_sha256(record.prf_result, sizeof(record.prf_result),
tls->master_secret, sizeof(tls->master_secret),
"client finished",
handshake_hash, sizeof(handshake_hash)
@ -1182,12 +1186,13 @@ static void tls_handshake(tls_state_t *tls)
//SvKey len=455^
// with TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA: 461 bytes:
// 0c 00|01|c9 03|00|17|41|04|cd|9b|b4|29|1f|f6|b0|c2|84|82|7f|29|6a|47|4e|ec|87|0b|c1|9c|69|e1|f8|c6|d0|53|e9|27|90|a5|c8|02|15|75...
dbg("got SERVER_KEY_EXCHANGE len:%u\n", len);
//need to save it
dbg("<< SERVER_KEY_EXCHANGE len:%u\n", len);
//probably need to save it
xread_tls_handshake_block(tls, 4);
}
// if (tls->inbuf[5] == HANDSHAKE_CERTIFICATE_REQUEST) {
// dbg("got CERTIFICATE_REQUEST\n");
// dbg("<< CERTIFICATE_REQUEST\n");
//RFC 5246: (in response to this,) "If no suitable certificate is available,
// the client MUST send a certificate message containing no
// certificates. That is, the certificate_list structure has a
@ -1197,10 +1202,11 @@ static void tls_handshake(tls_state_t *tls)
// (i.e. the same format as server certs)
// xread_tls_handshake_block(tls, 4);
// }
if (tls->inbuf[5] != HANDSHAKE_SERVER_HELLO_DONE)
tls_error_die(tls);
// 0e 000000 (len:0)
dbg("got SERVER_HELLO_DONE\n");
dbg("<< SERVER_HELLO_DONE\n");
send_client_key_exchange(tls);
@ -1213,7 +1219,7 @@ static void tls_handshake(tls_state_t *tls)
len = xread_tls_block(tls);
if (len != 1 || memcmp(tls->inbuf, rec_CHANGE_CIPHER_SPEC, 6) != 0)
tls_error_die(tls);
dbg("got CHANGE_CIPHER_SPEC\n");
dbg("<< CHANGE_CIPHER_SPEC\n");
tls->decrypt_on_read = 1;
/* we now should receive encrypted */
@ -1221,7 +1227,7 @@ static void tls_handshake(tls_state_t *tls)
len = xread_tls_block(tls);
if (len < 4 || tls->inbuf[5] != HANDSHAKE_FINISHED)
tls_error_die(tls);
dbg("got FINISHED\n");
dbg("<< FINISHED\n");
/* application data can be sent/received */
}
@ -1252,8 +1258,6 @@ int tls_main(int argc UNUSED_PARAM, char **argv)
return EXIT_SUCCESS;
}
//TODO: implement RFC 5746 (Renegotiation Indication Extension) - some servers will refuse to work with us otherwise
/* Unencryped SHA256 example:
* $ openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
* $ openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher NULL