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f18a1fd6f3
busybox/networking/tls.c
Denys Vlasenko f18a1fd6f3 tls: implement secp256r1 elliptic curve (aka P256) 
function                                             old     new   delta
sp_256_mod_mul_norm_10                                 -    1439   +1439
sp_256_ecc_mulmod_10                                   -    1363   +1363
sp_256_proj_point_dbl_10                               -     490    +490
p256_base                                              -     244    +244
static.sp_256_mont_sqr_10                              -     234    +234
static.sp_256_mont_mul_10                              -     214    +214
curve_P256_compute_pubkey_and_premaster                -     197    +197
static.sp_256_mont_reduce_10                           -     176    +176
static.sp_256_from_bin                                 -     149    +149
sp_256_to_bin                                          -     148    +148
tls_handshake                                       2046    2146    +100
static.sp_256_mul_add_10                               -      82     +82
.rodata                                           103275  103336     +61
static.sp_256_mont_sub_10                              -      52     +52
static.sp_256_mont_dbl_10                              -      52     +52
static.sp_256_cmp_10                                   -      43     +43
p256_mod                                               -      40     +40
static.sp_256_cond_sub_10                              -      32     +32
p256_mod_2                                             -      32     +32
sp_256_norm_10                                         -      31     +31
sp_256_cmp_equal_10                                    -      30     +30
sp_256_add_10                                          -      22     +22
addr_mask                                              -       8      +8
------------------------------------------------------------------------------
(add/remove: 22/0 grow/shrink: 2/0 up/down: 5239/0)          Total: 5239 bytes
   text	   data	    bss	    dec	    hex	filename
1018192	    559	   5020	1023771	  f9f1b	busybox_old
1023431	    559	   5020	1029010	  fb392	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2021-04-26 13:30:09 +02:00

2412 lines
86 KiB
C
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/*
* Copyright (C) 2017 Denys Vlasenko
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//config:config TLS
//config: bool #No description makes it a hidden option
//config: default n
//Note:
//Config.src also defines FEATURE_TLS_SHA1 option
//kbuild:lib-$(CONFIG_TLS) += tls.o
//kbuild:lib-$(CONFIG_TLS) += tls_pstm.o
//kbuild:lib-$(CONFIG_TLS) += tls_pstm_montgomery_reduce.o
//kbuild:lib-$(CONFIG_TLS) += tls_pstm_mul_comba.o
//kbuild:lib-$(CONFIG_TLS) += tls_pstm_sqr_comba.o
//kbuild:lib-$(CONFIG_TLS) += tls_aes.o
//kbuild:lib-$(CONFIG_TLS) += tls_aesgcm.o
//kbuild:lib-$(CONFIG_TLS) += tls_rsa.o
//kbuild:lib-$(CONFIG_TLS) += tls_fe.o
//kbuild:lib-$(CONFIG_TLS) += tls_sp_c32.o
#include "tls.h"
// works against "openssl s_server -cipher NULL"
// and against wolfssl-3.9.10-stable/examples/server/server.c:
#define ALLOW_RSA_NULL_SHA256 0 // for testing (does everything except encrypting)
//Tested against kernel.org:
//#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA // ok, recvs SERVER_KEY_EXCHANGE *** matrixssl uses this on my box
//#define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // ok, no SERVER_KEY_EXCHANGE
//#define CIPHER_ID TLS_DH_anon_WITH_AES_256_CBC_SHA // SSL_ALERT_HANDSHAKE_FAILURE
//^^^^^^^^^^^^^^^^^^^^^^^ (tested b/c this one doesn't req server certs... no luck, server refuses it)
//#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 // SSL_ALERT_HANDSHAKE_FAILURE
//#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
//#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 // ok, recvs SERVER_KEY_EXCHANGE
//#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
//#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384
//#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
//#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384
//#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
//#define CIPHER_ID TLS_RSA_WITH_AES_256_GCM_SHA384 // ok, no SERVER_KEY_EXCHANGE
//#define CIPHER_ID TLS_RSA_WITH_AES_128_GCM_SHA256 // ok, no SERVER_KEY_EXCHANGE
// works against wolfssl-3.9.10-stable/examples/server/server.c
// 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 -cipher AES256-SHA256
// fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -cipher AES256-GCM-SHA384
// fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -cipher AES128-SHA256
// ok: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -cipher AES128-GCM-SHA256
// ok: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -cipher AES128-SHA
// (TLS_RSA_WITH_AES_128_CBC_SHA - in TLS 1.2 it's mandated to be always supported)
//#define CIPHER_ID1 TLS_RSA_WITH_AES_256_CBC_SHA256 //0x003D
// Works with "wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.9.5.tar.xz"
//#define CIPHER_ID2 TLS_RSA_WITH_AES_128_CBC_SHA //0x002F
// bug #11456:
// ftp.openbsd.org only supports ECDHE-RSA-AESnnn-GCM-SHAnnn or ECDHE-RSA-CHACHA20-POLY1305
//#define CIPHER_ID3 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 //0xC02F
// host is.gd accepts only ECDHE-ECDSA-foo (the simplest which works: ECDHE-ECDSA-AES128-SHA 0xC009)
//#define CIPHER_ID4 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA //0xC009
#define TLS_DEBUG 0
#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__)
#else
# define dbg(...) ((void)0)
#endif
#if TLS_DEBUG_DER
# define dbg_der(...) fprintf(stderr, __VA_ARGS__)
#else
# define dbg_der(...) ((void)0)
#endif
//TLS 1.2
#define TLS_MAJ 3
#define TLS_MIN 3
#define RECORD_TYPE_CHANGE_CIPHER_SPEC 20 /* 0x14 */
#define RECORD_TYPE_ALERT 21 /* 0x15 */
#define RECORD_TYPE_HANDSHAKE 22 /* 0x16 */
#define RECORD_TYPE_APPLICATION_DATA 23 /* 0x17 */
#define HANDSHAKE_HELLO_REQUEST 0 /* 0x00 */
#define HANDSHAKE_CLIENT_HELLO 1 /* 0x01 */
#define HANDSHAKE_SERVER_HELLO 2 /* 0x02 */
#define HANDSHAKE_HELLO_VERIFY_REQUEST 3 /* 0x03 */
#define HANDSHAKE_NEW_SESSION_TICKET 4 /* 0x04 */
#define HANDSHAKE_CERTIFICATE 11 /* 0x0b */
#define HANDSHAKE_SERVER_KEY_EXCHANGE 12 /* 0x0c */
#define HANDSHAKE_CERTIFICATE_REQUEST 13 /* 0x0d */
#define HANDSHAKE_SERVER_HELLO_DONE 14 /* 0x0e */
#define HANDSHAKE_CERTIFICATE_VERIFY 15 /* 0x0f */
#define HANDSHAKE_CLIENT_KEY_EXCHANGE 16 /* 0x10 */
#define HANDSHAKE_FINISHED 20 /* 0x14 */
#define TLS_EMPTY_RENEGOTIATION_INFO_SCSV 0x00FF /* not a real cipher id... */
#define SSL_NULL_WITH_NULL_NULL 0x0000
#define SSL_RSA_WITH_NULL_MD5 0x0001
#define SSL_RSA_WITH_NULL_SHA 0x0002
#define SSL_RSA_WITH_RC4_128_MD5 0x0004
#define SSL_RSA_WITH_RC4_128_SHA 0x0005
#define TLS_RSA_WITH_IDEA_CBC_SHA 0x0007 /* 7 */
#define SSL_RSA_WITH_3DES_EDE_CBC_SHA 0x000A /* 10 */
#define SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA 0x0016 /* 22 */
#define SSL_DH_anon_WITH_RC4_128_MD5 0x0018 /* 24 */
#define SSL_DH_anon_WITH_3DES_EDE_CBC_SHA 0x001B /* 27 */
#define TLS_RSA_WITH_AES_128_CBC_SHA 0x002F /*SSLv3 Kx=RSA Au=RSA Enc=AES(128) Mac=SHA1 */
#define TLS_DHE_RSA_WITH_AES_128_CBC_SHA 0x0033 /* 51 */
#define TLS_DH_anon_WITH_AES_128_CBC_SHA 0x0034 /* 52 */
#define TLS_RSA_WITH_AES_256_CBC_SHA 0x0035 /* 53 */
#define TLS_DHE_RSA_WITH_AES_256_CBC_SHA 0x0039 /* 57 */
#define TLS_DH_anon_WITH_AES_256_CBC_SHA 0x003A /* 58 */
#define TLS_RSA_WITH_NULL_SHA256 0x003B /* 59 */
#define TLS_RSA_WITH_AES_128_CBC_SHA256 0x003C /* 60 */
#define TLS_RSA_WITH_AES_256_CBC_SHA256 0x003D /* 61 */
#define TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 0x0067 /* 103 */
#define TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 0x006B /* 107 */
#define TLS_PSK_WITH_AES_128_CBC_SHA 0x008C /* 140 */
#define TLS_PSK_WITH_AES_256_CBC_SHA 0x008D /* 141 */
#define TLS_DHE_PSK_WITH_AES_128_CBC_SHA 0x0090 /* 144 */
#define TLS_DHE_PSK_WITH_AES_256_CBC_SHA 0x0091 /* 145 */
#define TLS_RSA_WITH_SEED_CBC_SHA 0x0096 /* 150 */
#define TLS_RSA_WITH_AES_128_GCM_SHA256 0x009C /*TLSv1.2 Kx=RSA Au=RSA Enc=AESGCM(128) Mac=AEAD */
#define TLS_RSA_WITH_AES_256_GCM_SHA384 0x009D /*TLSv1.2 Kx=RSA Au=RSA Enc=AESGCM(256) Mac=AEAD */
#define TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 0x009E /*TLSv1.2 Kx=DH Au=RSA Enc=AESGCM(128) Mac=AEAD */
#define TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 0x009F /*TLSv1.2 Kx=DH Au=RSA Enc=AESGCM(256) Mac=AEAD */
#define TLS_DH_anon_WITH_AES_128_GCM_SHA256 0x00A6 /* RFC 5288 */
#define TLS_DH_anon_WITH_AES_256_GCM_SHA384 0x00A7 /* RFC 5288 */
#define TLS_PSK_WITH_AES_128_CBC_SHA256 0x00AE /* 174 */
#define TLS_PSK_WITH_AES_256_CBC_SHA384 0x00AF /* 175 */
#define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA 0xC004 /* 49156 */
#define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA 0xC005 /* 49157 */
#define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA 0xC009 /*TLSv1 Kx=ECDH Au=ECDSA Enc=AES(128) Mac=SHA1 */
#define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA 0xC00A /*TLSv1 Kx=ECDH Au=ECDSA Enc=AES(256) Mac=SHA1 */
#define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA 0xC00E /* 49166 */
#define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA 0xC00F /* 49167 */
#define TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA 0xC012 /* 49170 */
#define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA 0xC013 /*TLSv1 Kx=ECDH Au=RSA Enc=AES(128) Mac=SHA1 */
#define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA 0xC014 /*TLSv1 Kx=ECDH Au=RSA Enc=AES(256) Mac=SHA1 */
#define TLS_ECDH_anon_WITH_AES_128_CBC_SHA 0xC018 /* RFC 4492 */
#define TLS_ECDH_anon_WITH_AES_256_CBC_SHA 0xC019 /* RFC 4492 */
#define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 0xC023 /*TLSv1.2 Kx=ECDH Au=ECDSA Enc=AES(128) Mac=SHA256 */
#define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 0xC024 /*TLSv1.2 Kx=ECDH Au=ECDSA Enc=AES(256) Mac=SHA384 */
#define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 0xC025 /* 49189 */
#define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 0xC026 /* 49190 */
#define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 0xC027 /*TLSv1.2 Kx=ECDH Au=RSA Enc=AES(128) Mac=SHA256 */
#define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 0xC028 /*TLSv1.2 Kx=ECDH Au=RSA Enc=AES(256) Mac=SHA384 */
#define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256 0xC029 /* 49193 */
#define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384 0xC02A /* 49194 */
/* RFC 5288 "AES Galois Counter Mode (GCM) Cipher Suites for TLS" */
#define TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 0xC02B /*TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESGCM(128) Mac=AEAD */
#define TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 0xC02C /*TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESGCM(256) Mac=AEAD */
#define TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 0xC02D /* 49197 */
#define TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 0xC02E /* 49198 */
#define TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 0xC02F /*TLSv1.2 Kx=ECDH Au=RSA Enc=AESGCM(128) Mac=AEAD */
#define TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 0xC030 /*TLSv1.2 Kx=ECDH Au=RSA Enc=AESGCM(256) Mac=AEAD */
#define TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 0xC031 /* 49201 */
#define TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384 0xC032 /* 49202 */
#define TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA 0xC035
#define TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA 0xC036
#define TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256 0xC037
#define TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384 0xC038
/* From http://wiki.mozilla.org/Security/Server_Side_TLS */
/* and 'openssl ciphers -V -stdname' */
#define TLS_RSA_WITH_AES_128_CCM 0xC09C /*TLSv1.2 Kx=RSA Au=RSA Enc=AESCCM(128) Mac=AEAD */
#define TLS_RSA_WITH_AES_256_CCM 0xC09D /*TLSv1.2 Kx=RSA Au=RSA Enc=AESCCM(256) Mac=AEAD */
#define TLS_DHE_RSA_WITH_AES_128_CCM 0xC09E /*TLSv1.2 Kx=DH Au=RSA Enc=AESCCM(128) Mac=AEAD */
#define TLS_DHE_RSA_WITH_AES_256_CCM 0xC09F /*TLSv1.2 Kx=DH Au=RSA Enc=AESCCM(256) Mac=AEAD */
#define TLS_RSA_WITH_AES_128_CCM_8 0xC0A0 /*TLSv1.2 Kx=RSA Au=RSA Enc=AESCCM8(128) Mac=AEAD */
#define TLS_RSA_WITH_AES_256_CCM_8 0xC0A1 /*TLSv1.2 Kx=RSA Au=RSA Enc=AESCCM8(256) Mac=AEAD */
#define TLS_DHE_RSA_WITH_AES_128_CCM_8 0xC0A2 /*TLSv1.2 Kx=DH Au=RSA Enc=AESCCM8(128) Mac=AEAD */
#define TLS_DHE_RSA_WITH_AES_256_CCM_8 0xC0A3 /*TLSv1.2 Kx=DH Au=RSA Enc=AESCCM8(256) Mac=AEAD */
#define TLS_ECDHE_ECDSA_WITH_AES_128_CCM 0xC0AC /*TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESCCM(128) Mac=AEAD */
#define TLS_ECDHE_ECDSA_WITH_AES_256_CCM 0xC0AD /*TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESCCM(256) Mac=AEAD */
#define TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 0xC0AE /*TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESCCM8(128) Mac=AEAD */
#define TLS_ECDHE_ECDSA_WITH_AES_256_CCM_8 0xC0AF /*TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESCCM8(256) Mac=AEAD */
#define TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 0xCCA8 /*TLSv1.2 Kx=ECDH Au=RSA Enc=CHACHA20/POLY1305(256) Mac=AEAD */
#define TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 0xCCA9 /*TLSv1.2 Kx=ECDH Au=ECDSA Enc=CHACHA20/POLY1305(256) Mac=AEAD */
#define TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256 0xCCAA /*TLSv1.2 Kx=DH Au=RSA Enc=CHACHA20/POLY1305(256) Mac=AEAD */
#define TLS_AES_128_GCM_SHA256 0x1301 /*TLSv1.3 Kx=any Au=any Enc=AESGCM(128) Mac=AEAD */
#define TLS_AES_256_GCM_SHA384 0x1302 /*TLSv1.3 Kx=any Au=any Enc=AESGCM(256) Mac=AEAD */
#define TLS_CHACHA20_POLY1305_SHA256 0x1303 /*TLSv1.3 Kx=any Au=any Enc=CHACHA20/POLY1305(256) Mac=AEAD */
#define TLS_AES_128_CCM_SHA256 0x1304 /*TLSv1.3 Kx=any Au=any Enc=AESCCM(128) Mac=AEAD */
/* Might go to libbb.h */
#define TLS_MAX_CRYPTBLOCK_SIZE 16
#define TLS_MAX_OUTBUF (1 << 14)
enum {
SHA_INSIZE = 64,
AES128_KEYSIZE = 16,
AES256_KEYSIZE = 32,
RSA_PREMASTER_SIZE = 48,
RECHDR_LEN = 5,
/* 8 = 3+5. 3 extra bytes result in record data being 32-bit aligned */
OUTBUF_PFX = 8 + AES_BLOCK_SIZE, /* header + IV */
OUTBUF_SFX = TLS_MAX_MAC_SIZE + TLS_MAX_CRYPTBLOCK_SIZE, /* MAC + padding */
// RFC 5246:
// | 6.2.1. Fragmentation
// | The record layer fragments information blocks into TLSPlaintext
// | records carrying data in chunks of 2^14 bytes or less. Client
// | message boundaries are not preserved in the record layer (i.e.,
// | multiple client messages of the same ContentType MAY be coalesced
// | into a single TLSPlaintext record, or a single message MAY be
// | fragmented across several records)
// |...
// | length
// | The length (in bytes) of the following TLSPlaintext.fragment.
// | The length MUST NOT exceed 2^14.
// |...
// | 6.2.2. Record Compression and Decompression
// |...
// | Compression must be lossless and may not increase the content length
// | by more than 1024 bytes. If the decompression function encounters a
// | TLSCompressed.fragment that would decompress to a length in excess of
// | 2^14 bytes, it MUST report a fatal decompression failure error.
// |...
// | length
// | The length (in bytes) of the following TLSCompressed.fragment.
// | The length MUST NOT exceed 2^14 + 1024.
// |...
// | 6.2.3. Record Payload Protection
// | The encryption and MAC functions translate a TLSCompressed
// | structure into a TLSCiphertext. The decryption functions reverse
// | the process. The MAC of the record also includes a sequence
// | number so that missing, extra, or repeated messages are
// | detectable.
// |...
// | length
// | The length (in bytes) of the following TLSCiphertext.fragment.
// | The length MUST NOT exceed 2^14 + 2048.
MAX_INBUF = RECHDR_LEN + (1 << 14) + 2048,
/* Bits for tls->flags */
NEED_EC_KEY = 1 << 0,
GOT_CERT_RSA_KEY_ALG = 1 << 1,
GOT_CERT_ECDSA_KEY_ALG = 1 << 2, // so far unused
GOT_EC_KEY = 1 << 3,
GOT_EC_CURVE_X25519 = 1 << 4, // else P256
ENCRYPTION_AESGCM = 1 << 5, // else AES-SHA (or NULL-SHA if ALLOW_RSA_NULL_SHA256=1)
ENCRYPT_ON_WRITE = 1 << 6,
};
struct record_hdr {
uint8_t type;
uint8_t proto_maj, proto_min;
uint8_t len16_hi, len16_lo;
};
struct tls_handshake_data {
/* In bbox, md5/sha1/sha256 ctx's are the same structure */
md5sha_ctx_t handshake_hash_ctx;
uint8_t client_and_server_rand32[2 * 32];
uint8_t master_secret[48];
//TODO: store just the DER key here, parse/use/delete it when sending client key
//this way it will stay key type agnostic here.
psRsaKey_t server_rsa_pub_key;
/* peer's elliptic curve key data */
/* for x25519, it contains one point in first 32 bytes */
/* for P256, it contains x,y point pair, each 32 bytes long */
uint8_t ecc_pub_key32[2 * 32];
/* HANDSHAKE HASH: */
//unsigned saved_client_hello_size;
//uint8_t saved_client_hello[1];
};
static unsigned get24be(const uint8_t *p)
{
return 0x100*(0x100*p[0] + p[1]) + p[2];
}
#if TLS_DEBUG
/* Nondestructively see the current hash value */
# if TLS_DEBUG_HASH
static unsigned sha_peek(md5sha_ctx_t *ctx, void *buffer)
{
md5sha_ctx_t ctx_copy = *ctx; /* struct copy */
return sha_end(&ctx_copy, buffer);
}
# endif
static void dump_hex(const char *fmt, const void *vp, int len)
{
char hexbuf[32 * 1024 + 4];
const uint8_t *p = vp;
bin2hex(hexbuf, (void*)p, len)[0] = '\0';
dbg(fmt, hexbuf);
}
static void dump_tls_record(const void *vp, int len)
{
const uint8_t *p = vp;
while (len > 0) {
unsigned xhdr_len;
if (len < RECHDR_LEN) {
dump_hex("< |%s|\n", p, len);
return;
}
xhdr_len = 0x100*p[3] + p[4];
dbg("< hdr_type:%u ver:%u.%u len:%u", p[0], p[1], p[2], xhdr_len);
p += RECHDR_LEN;
len -= RECHDR_LEN;
if (len >= 4 && p[-RECHDR_LEN] == RECORD_TYPE_HANDSHAKE) {
unsigned len24 = get24be(p + 1);
dbg(" type:%u len24:%u", p[0], len24);
}
if (xhdr_len > len)
xhdr_len = len;
dump_hex(" |%s|\n", p, xhdr_len);
p += xhdr_len;
len -= xhdr_len;
}
}
#else
# define dump_hex(...) ((void)0)
# define dump_tls_record(...) ((void)0)
#endif
void FAST_FUNC tls_get_random(void *buf, unsigned len)
{
if (len != open_read_close("/dev/urandom", buf, len))
xfunc_die();
}
static void xorbuf3(void *dst, const void *src1, const void *src2, unsigned count)
{
uint8_t *d = dst;
const uint8_t *s1 = src1;
const uint8_t* s2 = src2;
while (count--)
*d++ = *s1++ ^ *s2++;
}
void FAST_FUNC xorbuf(void *dst, const void *src, unsigned count)
{
xorbuf3(dst, dst, src, count);
}
void FAST_FUNC xorbuf_aligned_AES_BLOCK_SIZE(void *dst, const void *src)
{
unsigned long *d = dst;
const unsigned long *s = src;
d[0] ^= s[0];
#if ULONG_MAX <= 0xffffffffffffffff
d[1] ^= s[1];
#if ULONG_MAX == 0xffffffff
d[2] ^= s[2];
d[3] ^= s[3];
#endif
#endif
}
#if !TLS_DEBUG_HASH
# define hash_handshake(tls, fmt, buffer, len) \
hash_handshake(tls, buffer, len)
#endif
static void hash_handshake(tls_state_t *tls, const char *fmt, const void *buffer, unsigned len)
{
md5sha_hash(&tls->hsd->handshake_hash_ctx, buffer, len);
#if TLS_DEBUG_HASH
{
uint8_t h[TLS_MAX_MAC_SIZE];
dump_hex(fmt, buffer, len);
dbg(" (%u bytes) ", (int)len);
len = sha_peek(&tls->hsd->handshake_hash_ctx, h);
if (ENABLE_FEATURE_TLS_SHA1 && len == SHA1_OUTSIZE)
dump_hex("sha1:%s\n", h, len);
else
if (len == SHA256_OUTSIZE)
dump_hex("sha256:%s\n", h, len);
else
dump_hex("sha???:%s\n", h, len);
}
#endif
}
#if !ENABLE_FEATURE_TLS_SHA1
# define TLS_MAC_SIZE(tls) SHA256_OUTSIZE
#else
# define TLS_MAC_SIZE(tls) (tls)->MAC_size
#endif
// RFC 2104:
// HMAC(key, text) based on a hash H (say, sha256) is:
// ipad = [0x36 x INSIZE]
// opad = [0x5c x INSIZE]
// HMAC(key, text) = H((key XOR opad) + H((key XOR ipad) + text))
//
// H(key XOR opad) and H(key XOR ipad) can be precomputed
// if we often need HMAC hmac with the same key.
//
// text is often given in disjoint pieces.
typedef struct hmac_precomputed {
md5sha_ctx_t hashed_key_xor_ipad;
md5sha_ctx_t hashed_key_xor_opad;
} hmac_precomputed_t;
typedef void md5sha_begin_func(md5sha_ctx_t *ctx) FAST_FUNC;
#if !ENABLE_FEATURE_TLS_SHA1
#define hmac_begin(pre,key,key_size,begin) \
hmac_begin(pre,key,key_size)
#define begin sha256_begin
#endif
static void hmac_begin(hmac_precomputed_t *pre, uint8_t *key, unsigned key_size, md5sha_begin_func *begin)
{
uint8_t key_xor_ipad[SHA_INSIZE];
uint8_t key_xor_opad[SHA_INSIZE];
// uint8_t tempkey[SHA1_OUTSIZE < SHA256_OUTSIZE ? SHA256_OUTSIZE : SHA1_OUTSIZE];
unsigned i;
// "The authentication key can be of any length up to INSIZE, the
// block length of the hash function. Applications that use keys longer
// than INSIZE bytes will first hash the key using H and then use the
// resultant OUTSIZE byte string as the actual key to HMAC."
if (key_size > SHA_INSIZE) {
bb_simple_error_msg_and_die("HMAC key>64"); //does not happen (yet?)
// md5sha_ctx_t ctx;
// begin(&ctx);
// md5sha_hash(&ctx, key, key_size);
// key_size = sha_end(&ctx, tempkey);
// //key = tempkey; - right? RIGHT? why does it work without this?
// // because SHA_INSIZE is 64, but hmac() is always called with
// // key_size = tls->MAC_size = SHA1/256_OUTSIZE (20 or 32),
// // and prf_hmac_sha256() -> hmac_sha256() key sizes are:
// // - RSA_PREMASTER_SIZE is 48
// // - CURVE25519_KEYSIZE is 32
// // - master_secret[] is 48
}
for (i = 0; i < key_size; i++) {
key_xor_ipad[i] = key[i] ^ 0x36;
key_xor_opad[i] = key[i] ^ 0x5c;
}
for (; i < SHA_INSIZE; i++) {
key_xor_ipad[i] = 0x36;
key_xor_opad[i] = 0x5c;
}
begin(&pre->hashed_key_xor_ipad);
begin(&pre->hashed_key_xor_opad);
md5sha_hash(&pre->hashed_key_xor_ipad, key_xor_ipad, SHA_INSIZE);
md5sha_hash(&pre->hashed_key_xor_opad, key_xor_opad, SHA_INSIZE);
}
#undef begin
static unsigned hmac_sha_precomputed_v(
hmac_precomputed_t *pre,
uint8_t *out,
va_list va)
{
uint8_t *text;
unsigned len;
/* pre->hashed_key_xor_ipad contains unclosed "H((key XOR ipad) +" state */
/* pre->hashed_key_xor_opad contains unclosed "H((key XOR opad) +" state */
/* calculate out = H((key XOR ipad) + text) */
while ((text = va_arg(va, uint8_t*)) != NULL) {
unsigned text_size = va_arg(va, unsigned);
md5sha_hash(&pre->hashed_key_xor_ipad, text, text_size);
}
len = sha_end(&pre->hashed_key_xor_ipad, out);
/* out = H((key XOR opad) + out) */
md5sha_hash(&pre->hashed_key_xor_opad, out, len);
return sha_end(&pre->hashed_key_xor_opad, out);
}
static unsigned hmac_sha_precomputed(hmac_precomputed_t *pre_init, uint8_t *out, ...)
{
hmac_precomputed_t pre;
va_list va;
unsigned len;
va_start(va, out);
pre = *pre_init; /* struct copy */
len = hmac_sha_precomputed_v(&pre, out, va);
va_end(va);
return len;
}
#if !ENABLE_FEATURE_TLS_SHA1
#define hmac(tls,out,key,key_size,...) \
hmac(out,key,key_size, __VA_ARGS__)
#endif
static unsigned hmac(tls_state_t *tls, uint8_t *out, uint8_t *key, unsigned key_size, ...)
{
hmac_precomputed_t pre;
va_list va;
unsigned len;
va_start(va, key_size);
hmac_begin(&pre, key, key_size,
(ENABLE_FEATURE_TLS_SHA1 && tls->MAC_size == SHA1_OUTSIZE)
? sha1_begin
: sha256_begin
);
len = hmac_sha_precomputed_v(&pre, out, va);
va_end(va);
return len;
}
// RFC 5246:
// 5. HMAC and the Pseudorandom Function
//...
// In this section, we define one PRF, based on HMAC. This PRF with the
// SHA-256 hash function is used for all cipher suites defined in this
// document and in TLS documents published prior to this document when
// TLS 1.2 is negotiated.
// ^^^^^^^^^^^^^ IMPORTANT!
// PRF uses sha256 regardless of cipher for all ciphers
// defined by RFC 5246. It's not sha1 for AES_128_CBC_SHA!
// However, for _SHA384 ciphers, it's sha384. See RFC 5288,5289.
//...
// P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) +
// HMAC_hash(secret, A(2) + seed) +
// HMAC_hash(secret, A(3) + seed) + ...
// where + indicates concatenation.
// A() is defined as:
// A(0) = seed
// A(1) = HMAC_hash(secret, A(0)) = HMAC_hash(secret, seed)
// A(i) = HMAC_hash(secret, A(i-1))
// P_hash can be iterated as many times as necessary to produce the
// required quantity of data. For example, if P_SHA256 is being used to
// create 80 bytes of data, it will have to be iterated three times
// (through A(3)), creating 96 bytes of output data; the last 16 bytes
// of the final iteration will then be discarded, leaving 80 bytes of
// output data.
//
// TLS's PRF is created by applying P_hash to the secret as:
//
// PRF(secret, label, seed) = P_<hash>(secret, label + seed)
//
// The label is an ASCII string.
//
// RFC 5288:
// For cipher suites ending with _SHA256, the PRF is the TLS PRF
// with SHA-256 as the hash function.
// For cipher suites ending with _SHA384, the PRF is the TLS PRF
// with SHA-384 as the hash function.
static void prf_hmac_sha256(/*tls_state_t *tls,*/
uint8_t *outbuf, unsigned outbuf_size,
uint8_t *secret, unsigned secret_size,
const char *label,
uint8_t *seed, unsigned seed_size)
{
hmac_precomputed_t pre;
uint8_t a[TLS_MAX_MAC_SIZE];
uint8_t *out_p = outbuf;
unsigned label_size = strlen(label);
unsigned MAC_size = SHA256_OUTSIZE;
/* In P_hash() calculation, "seed" is "label + seed": */
#define SEED label, label_size, seed, seed_size
#define A a, MAC_size
hmac_begin(&pre, secret, secret_size, sha256_begin);
/* A(1) = HMAC_hash(secret, seed) */
hmac_sha_precomputed(&pre, a, SEED, NULL);
for (;;) {
/* HMAC_hash(secret, A(1) + seed) */
if (outbuf_size <= MAC_size) {
/* Last, possibly incomplete, block */
/* (use a[] as temp buffer) */
hmac_sha_precomputed(&pre, a, A, SEED, NULL);
memcpy(out_p, a, outbuf_size);
return;
}
/* Not last block. Store directly to result buffer */
hmac_sha_precomputed(&pre, out_p, A, SEED, NULL);
out_p += MAC_size;
outbuf_size -= MAC_size;
/* A(2) = HMAC_hash(secret, A(1)) */
hmac_sha_precomputed(&pre, a, A, NULL);
}
#undef A
#undef SECRET
#undef SEED
}
static void bad_record_die(tls_state_t *tls, const char *expected, int len)
{
bb_error_msg("got bad TLS record (len:%d) while expecting %s", len, expected);
if (len > 0) {
uint8_t *p = tls->inbuf;
if (len > 99)
len = 99; /* don't flood, a few lines should be enough */
do {
fprintf(stderr, " %02x", *p++);
len--;
} while (len != 0);
fputc('\n', stderr);
}
xfunc_die();
}
static void tls_error_die(tls_state_t *tls, int line)
{
dump_tls_record(tls->inbuf, tls->ofs_to_buffered + tls->buffered_size);
bb_error_msg_and_die("tls error at line %d cipher:%04x", line, tls->cipher_id);
}
#define tls_error_die(tls) tls_error_die(tls, __LINE__)
#if 0 //UNUSED
static void tls_free_inbuf(tls_state_t *tls)
{
if (tls->buffered_size == 0) {
free(tls->inbuf);
tls->inbuf_size = 0;
tls->inbuf = NULL;
}
}
#endif
static void tls_free_outbuf(tls_state_t *tls)
{
free(tls->outbuf);
tls->outbuf_size = 0;
tls->outbuf = NULL;
}
static void *tls_get_outbuf(tls_state_t *tls, int len)
{
if (len > TLS_MAX_OUTBUF)
xfunc_die();
len += OUTBUF_PFX + OUTBUF_SFX;
if (tls->outbuf_size < len) {
tls->outbuf_size = len;
tls->outbuf = xrealloc(tls->outbuf, len);
}
return tls->outbuf + OUTBUF_PFX;
}
static void *tls_get_zeroed_outbuf(tls_state_t *tls, int len)
{
void *record = tls_get_outbuf(tls, len);
memset(record, 0, len);
return record;
}
static void xwrite_encrypted_and_hmac_signed(tls_state_t *tls, unsigned size, unsigned type)
{
uint8_t *buf = tls->outbuf + OUTBUF_PFX;
struct record_hdr *xhdr;
uint8_t padding_length;
xhdr = (void*)(buf - RECHDR_LEN);
if (!ALLOW_RSA_NULL_SHA256 /* if "no encryption" can't be selected */
|| tls->cipher_id != TLS_RSA_WITH_NULL_SHA256 /* or if it wasn't selected */
) {
xhdr = (void*)(buf - RECHDR_LEN - AES_BLOCK_SIZE); /* place for IV */
}
xhdr->type = type;
xhdr->proto_maj = TLS_MAJ;
xhdr->proto_min = TLS_MIN;
/* fake unencrypted record len for MAC calculation */
xhdr->len16_hi = size >> 8;
xhdr->len16_lo = size & 0xff;
/* Calculate MAC signature */
hmac(tls, buf + size, /* result */
tls->client_write_MAC_key, TLS_MAC_SIZE(tls),
&tls->write_seq64_be, sizeof(tls->write_seq64_be),
xhdr, RECHDR_LEN,
buf, size,
NULL
);
tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be));
size += TLS_MAC_SIZE(tls);
// RFC 5246:
// 6.2.3.1. Null or Standard Stream Cipher
//
// Stream ciphers (including BulkCipherAlgorithm.null; see Appendix A.6)
// convert TLSCompressed.fragment structures to and from stream
// TLSCiphertext.fragment structures.
//
// stream-ciphered struct {
// opaque content[TLSCompressed.length];
// opaque MAC[SecurityParameters.mac_length];
// } GenericStreamCipher;
//
// The MAC is generated as:
// MAC(MAC_write_key, seq_num +
// TLSCompressed.type +
// TLSCompressed.version +
// TLSCompressed.length +
// TLSCompressed.fragment);
// where "+" denotes concatenation.
// seq_num
// The sequence number for this record.
// MAC
// The MAC algorithm specified by SecurityParameters.mac_algorithm.
//
// Note that the MAC is computed before encryption. The stream cipher
// encrypts the entire block, including the MAC.
//...
// Appendix C. Cipher Suite Definitions
//...
// MAC Algorithm mac_length mac_key_length
// -------- ----------- ---------- --------------
// SHA HMAC-SHA1 20 20
// SHA256 HMAC-SHA256 32 32
if (ALLOW_RSA_NULL_SHA256
&& tls->cipher_id == TLS_RSA_WITH_NULL_SHA256
) {
/* No encryption, only signing */
xhdr->len16_hi = size >> 8;
xhdr->len16_lo = size & 0xff;
dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
dbg("wrote %u bytes (NULL crypt, SHA256 hash)\n", size);
return;
}
// 6.2.3.2. CBC Block Cipher
// For block ciphers (such as 3DES or AES), the encryption and MAC
// functions convert TLSCompressed.fragment structures to and from block
// TLSCiphertext.fragment structures.
// struct {
// opaque IV[SecurityParameters.record_iv_length];
// block-ciphered struct {
// opaque content[TLSCompressed.length];
// opaque MAC[SecurityParameters.mac_length];
// uint8 padding[GenericBlockCipher.padding_length];
// uint8 padding_length;
// };
// } GenericBlockCipher;
//...
// IV
// The Initialization Vector (IV) SHOULD be chosen at random, and
// MUST be unpredictable. Note that in versions of TLS prior to 1.1,
// there was no IV field (...). For block ciphers, the IV length is
// of length SecurityParameters.record_iv_length, which is equal to the
// SecurityParameters.block_size.
// padding
// Padding that is added to force the length of the plaintext to be
// an integral multiple of the block cipher's block length.
// padding_length
// The padding length MUST be such that the total size of the
// GenericBlockCipher structure is a multiple of the cipher's block
// length. Legal values range from zero to 255, inclusive.
//...
// Appendix C. Cipher Suite Definitions
//...
// Key IV Block
// Cipher Type Material Size Size
// ------------ ------ -------- ---- -----
// AES_128_CBC Block 16 16 16
// AES_256_CBC Block 32 16 16
tls_get_random(buf - AES_BLOCK_SIZE, AES_BLOCK_SIZE); /* IV */
dbg("before crypt: 5 hdr + %u data + %u hash bytes\n",
size - TLS_MAC_SIZE(tls), TLS_MAC_SIZE(tls));
/* Fill IV and padding in outbuf */
// RFC is talking nonsense:
// "Padding that is added to force the length of the plaintext to be
// an integral multiple of the block cipher's block length."
// WRONG. _padding+padding_length_, not just _padding_,
// pads the data.
// IOW: padding_length is the last byte of padding[] array,
// contrary to what RFC depicts.
//
// What actually happens is that there is always padding.
// If you need one byte to reach BLOCKSIZE, this byte is 0x00.
// If you need two bytes, they are both 0x01.
// If you need three, they are 0x02,0x02,0x02. And so on.
// If you need no bytes to reach BLOCKSIZE, you have to pad a full
// BLOCKSIZE with bytes of value (BLOCKSIZE-1).
// It's ok to have more than minimum padding, but we do minimum.
padding_length = (~size) & (AES_BLOCK_SIZE - 1);
do {
buf[size++] = padding_length; /* padding */
} while ((size & (AES_BLOCK_SIZE - 1)) != 0);
/* Encrypt content+MAC+padding in place */
aes_cbc_encrypt(
&tls->aes_encrypt, /* selects 128/256 */
buf - AES_BLOCK_SIZE, /* IV */
buf, size, /* plaintext */
buf /* ciphertext */
);
/* Write out */
dbg("writing 5 + %u IV + %u encrypted bytes, padding_length:0x%02x\n",
AES_BLOCK_SIZE, size, padding_length);
size += AES_BLOCK_SIZE; /* + IV */
xhdr->len16_hi = size >> 8;
xhdr->len16_lo = size & 0xff;
dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
dbg("wrote %u bytes\n", (int)RECHDR_LEN + size);
}
/* Example how GCM encryption combines nonce, aad, input and generates
* "header | exp_nonce | encrypted output | tag":
* nonce:0d 6a 26 31 00 00 00 00 00 00 00 01 (implicit 4 bytes (derived from master secret), then explicit 8 bytes)
* aad: 00 00 00 00 00 00 00 01 17 03 03 00 1c
* in: 47 45 54 20 2f 69 6e 64 65 78 2e 68 74 6d 6c 20 48 54 54 50 2f 31 2e 30 0d 0a 0d 0a "GET /index.html HTTP/1.0\r\n\r\n" (0x1c bytes)
* out: f7 8a b2 8f 78 0e f6 d5 76 17 2e b5 6d 46 59 56 8b 46 9f 0b d9 2c 35 28 13 66 19 be
* tag: c2 86 ce 4a 50 4a d0 aa 50 b3 76 5c 49 2a 3f 33
* sent: 17 03 03 00 34|00 00 00 00 00 00 00 01|f7 8a b2 8f 78 0e f6 d5 76 17 2e b5 6d 46 59 56 8b 46 9f 0b d9 2c 35 28 13 66 19 be|c2 86 ce 4a 50 4a d0 aa 50 b3 76 5c 49 2a 3f 33
* .............................................^^ buf points here
*/
static void xwrite_encrypted_aesgcm(tls_state_t *tls, unsigned size, unsigned type)
{
#define COUNTER(v) (*(uint32_t*)(v + 12))
uint8_t aad[13 + 3] ALIGNED_long; /* +3 creates [16] buffer, simplifying GHASH() */
uint8_t nonce[12 + 4] ALIGNED_long; /* +4 creates space for AES block counter */
uint8_t scratch[AES_BLOCK_SIZE] ALIGNED_long; //[16]
uint8_t authtag[AES_BLOCK_SIZE] ALIGNED_long; //[16]
uint8_t *buf;
struct record_hdr *xhdr;
unsigned remaining;
unsigned cnt;
uint64_t t64;
buf = tls->outbuf + OUTBUF_PFX; /* see above for the byte it points to */
dump_hex("xwrite_encrypted_aesgcm plaintext:%s\n", buf, size);
xhdr = (void*)(buf - 8 - RECHDR_LEN);
xhdr->type = type; /* do it here so that "type" param no longer used */
aad[8] = type;
aad[9] = TLS_MAJ;
aad[10] = TLS_MIN;
aad[11] = size >> 8;
/* set aad[12], and clear aad[13..15] */
COUNTER(aad) = SWAP_LE32(size & 0xff);
memcpy(nonce, tls->client_write_IV, 4);
t64 = tls->write_seq64_be;
move_to_unaligned64(nonce + 4, t64);
move_to_unaligned64(aad, t64);
move_to_unaligned64(buf - 8, t64);
/* seq64 is not used later in this func, can increment here */
tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(t64));
cnt = 1;
remaining = size;
while (remaining != 0) {
unsigned n;
cnt++;
COUNTER(nonce) = htonl(cnt); /* yes, first cnt here is 2 (!) */
aes_encrypt_one_block(&tls->aes_encrypt, nonce, scratch);
n = remaining > AES_BLOCK_SIZE ? AES_BLOCK_SIZE : remaining;
xorbuf(buf, scratch, n);
buf += n;
remaining -= n;
}
aesgcm_GHASH(tls->H, aad, /*sizeof(aad),*/ tls->outbuf + OUTBUF_PFX, size, authtag /*, sizeof(authtag)*/);
COUNTER(nonce) = htonl(1);
aes_encrypt_one_block(&tls->aes_encrypt, nonce, scratch);
xorbuf_aligned_AES_BLOCK_SIZE(authtag, scratch);
memcpy(buf, authtag, sizeof(authtag));
/* Write out */
xhdr = (void*)(tls->outbuf + OUTBUF_PFX - 8 - RECHDR_LEN);
size += 8 + sizeof(authtag);
/*xhdr->type = type; - already is */
xhdr->proto_maj = TLS_MAJ;
xhdr->proto_min = TLS_MIN;
xhdr->len16_hi = size >> 8;
xhdr->len16_lo = size & 0xff;
size += RECHDR_LEN;
dump_raw_out(">> %s\n", xhdr, size);
xwrite(tls->ofd, xhdr, size);
dbg("wrote %u bytes\n", size);
#undef COUNTER
}
static void xwrite_encrypted(tls_state_t *tls, unsigned size, unsigned type)
{
if (!(tls->flags & ENCRYPTION_AESGCM)) {
xwrite_encrypted_and_hmac_signed(tls, size, type);
return;
}
xwrite_encrypted_aesgcm(tls, size, type);
}
static void xwrite_handshake_record(tls_state_t *tls, unsigned size)
{
uint8_t *buf = tls->outbuf + OUTBUF_PFX;
struct record_hdr *xhdr = (void*)(buf - RECHDR_LEN);
xhdr->type = RECORD_TYPE_HANDSHAKE;
xhdr->proto_maj = TLS_MAJ;
xhdr->proto_min = TLS_MIN;
xhdr->len16_hi = size >> 8;
xhdr->len16_lo = size & 0xff;
dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
dbg("wrote %u bytes\n", (int)RECHDR_LEN + size);
}
static void xwrite_and_update_handshake_hash(tls_state_t *tls, unsigned size)
{
if (!(tls->flags & ENCRYPT_ON_WRITE)) {
uint8_t *buf;
xwrite_handshake_record(tls, size);
/* Handshake hash does not include record headers */
buf = tls->outbuf + OUTBUF_PFX;
hash_handshake(tls, ">> hash:%s", buf, size);
return;
}
xwrite_encrypted(tls, size, RECORD_TYPE_HANDSHAKE);
}
static int tls_has_buffered_record(tls_state_t *tls)
{
int buffered = tls->buffered_size;
struct record_hdr *xhdr;
int rec_size;
if (buffered < RECHDR_LEN)
return 0;
xhdr = (void*)(tls->inbuf + tls->ofs_to_buffered);
rec_size = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
if (buffered < rec_size)
return 0;
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 void tls_aesgcm_decrypt(tls_state_t *tls, uint8_t *buf, int size)
{
#define COUNTER(v) (*(uint32_t*)(v + 12))
//uint8_t aad[13 + 3] ALIGNED_long; /* +3 creates [16] buffer, simplifying GHASH() */
uint8_t nonce[12 + 4] ALIGNED_long; /* +4 creates space for AES block counter */
uint8_t scratch[AES_BLOCK_SIZE] ALIGNED_long; //[16]
//uint8_t authtag[AES_BLOCK_SIZE] ALIGNED_long; //[16]
unsigned remaining;
unsigned cnt;
//memcpy(aad, buf, 8);
//aad[8] = type;
//aad[9] = TLS_MAJ;
//aad[10] = TLS_MIN;
//aad[11] = size >> 8;
///* set aad[12], and clear aad[13..15] */
//COUNTER(aad) = SWAP_LE32(size & 0xff);
memcpy(nonce, tls->server_write_IV, 4);
memcpy(nonce + 4, buf, 8);
cnt = 1;
remaining = size;
while (remaining != 0) {
unsigned n;
cnt++;
COUNTER(nonce) = htonl(cnt); /* yes, first cnt here is 2 (!) */
aes_encrypt_one_block(&tls->aes_decrypt, nonce, scratch);
n = remaining > AES_BLOCK_SIZE ? AES_BLOCK_SIZE : remaining;
xorbuf3(buf, scratch, buf + 8, n);
buf += n;
remaining -= n;
}
//aesgcm_GHASH(tls->H, aad, tls->inbuf + RECHDR_LEN, size, authtag);
//COUNTER(nonce) = htonl(1);
//aes_encrypt_one_block(&tls->aes_encrypt, nonce, scratch);
//xorbuf_aligned_AES_BLOCK_SIZE(authtag, scratch);
//memcmp(buf, authtag, sizeof(authtag)) || DIE("HASH DOES NOT MATCH!");
#undef COUNTER
}
static int tls_xread_record(tls_state_t *tls, const char *expected)
{
struct record_hdr *xhdr;
int sz;
int total;
int target;
again:
dbg("ofs_to_buffered:%u buffered_size:%u\n", tls->ofs_to_buffered, tls->buffered_size);
total = tls->buffered_size;
if (total != 0) {
memmove(tls->inbuf, tls->inbuf + tls->ofs_to_buffered, total);
//dbg("<< remaining at %d [%d] ", tls->ofs_to_buffered, total);
//dump_raw_in("<< %s\n", tls->inbuf, total);
}
errno = 0;
target = MAX_INBUF;
for (;;) {
int rem;
if (total >= RECHDR_LEN && target == MAX_INBUF) {
xhdr = (void*)tls->inbuf;
target = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
if (target > MAX_INBUF /* malformed input (too long) */
|| xhdr->proto_maj != TLS_MAJ
|| xhdr->proto_min != TLS_MIN
) {
sz = total < target ? total : target;
bad_record_die(tls, expected, sz);
}
dbg("xhdr type:%d ver:%d.%d len:%d\n",
xhdr->type, xhdr->proto_maj, xhdr->proto_min,
0x100 * xhdr->len16_hi + xhdr->len16_lo
);
}
/* if total >= target, we have a full packet (and possibly more)... */
if (total - target >= 0)
break;
/* input buffer is grown only as needed */
rem = tls->inbuf_size - total;
if (rem == 0) {
tls->inbuf_size += MAX_INBUF / 8;
if (tls->inbuf_size > MAX_INBUF)
tls->inbuf_size = MAX_INBUF;
dbg("inbuf_size:%d\n", tls->inbuf_size);
rem = tls->inbuf_size - total;
tls->inbuf = xrealloc(tls->inbuf, tls->inbuf_size);
}
sz = safe_read(tls->ifd, tls->inbuf + total, rem);
if (sz <= 0) {
if (sz == 0 && total == 0) {
/* "Abrupt" EOF, no TLS shutdown (seen from kernel.org) */
dbg("EOF (without TLS shutdown) from peer\n");
tls->buffered_size = 0;
goto end;
}
bb_perror_msg_and_die("short read, have only %d", total);
}
dump_raw_in("<< %s\n", tls->inbuf + total, sz);
total += sz;
}
tls->buffered_size = total - target;
tls->ofs_to_buffered = target;
//dbg("<< stashing at %d [%d] ", tls->ofs_to_buffered, tls->buffered_size);
//dump_hex("<< %s\n", tls->inbuf + tls->ofs_to_buffered, tls->buffered_size);
sz = target - RECHDR_LEN;
/* Needs to be decrypted? */
if (tls->min_encrypted_len_on_read != 0) {
if (sz < (int)tls->min_encrypted_len_on_read)
bb_error_msg_and_die("bad encrypted len:%u", sz);
if (tls->flags & ENCRYPTION_AESGCM) {
/* AESGCM */
uint8_t *p = tls->inbuf + RECHDR_LEN;
sz -= 8 + AES_BLOCK_SIZE; /* we will overwrite nonce, drop hash */
tls_aesgcm_decrypt(tls, p, sz);
dbg("encrypted size:%u\n", sz);
} else
if (tls->min_encrypted_len_on_read > TLS_MAC_SIZE(tls)) {
/* AES+SHA */
uint8_t *p = tls->inbuf + RECHDR_LEN;
int padding_len;
if (sz & (AES_BLOCK_SIZE-1))
bb_error_msg_and_die("bad encrypted len:%u", sz);
/* Decrypt content+MAC+padding, moving it over IV in the process */
sz -= AES_BLOCK_SIZE; /* we will overwrite IV now */
aes_cbc_decrypt(
&tls->aes_decrypt, /* selects 128/256 */
p, /* IV */
p + AES_BLOCK_SIZE, sz, /* ciphertext */
p /* plaintext */
);
padding_len = p[sz - 1];
dbg("encrypted size:%u type:0x%02x padding_length:0x%02x\n", sz, p[0], padding_len);
padding_len++;
sz -= TLS_MAC_SIZE(tls) + padding_len; /* drop MAC and padding */
} else {
/* if nonzero, then it's TLS_RSA_WITH_NULL_SHA256: drop MAC */
/* else: no encryption yet on input, subtract zero = NOP */
sz -= tls->min_encrypted_len_on_read;
}
}
if (sz < 0)
bb_simple_error_msg_and_die("encrypted data too short");
//dump_hex("<< %s\n", tls->inbuf, RECHDR_LEN + sz);
xhdr = (void*)tls->inbuf;
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] not 1 or 2: not defined in protocol */
sz = 0;
goto end;
}
/* RFC 5246 is not saying it explicitly, but sha256 hash
* in our FINISHED record must include data of incoming packets too!
*/
if (tls->inbuf[0] == RECORD_TYPE_HANDSHAKE
/* HANDSHAKE HASH: */
// && do_we_know_which_hash_to_use /* server_hello() might not know it in the future! */
) {
hash_handshake(tls, "<< hash:%s", tls->inbuf + RECHDR_LEN, sz);
}
end:
dbg("got block len:%u\n", sz);
return sz;
}
static void binary_to_pstm(pstm_int *pstm_n, uint8_t *bin_ptr, unsigned len)
{
pstm_init_for_read_unsigned_bin(/*pool:*/ NULL, pstm_n, len);
pstm_read_unsigned_bin(pstm_n, bin_ptr, len);
//return bin_ptr + len;
}
/*
* DER parsing routines
*/
static unsigned get_der_len(uint8_t **bodyp, uint8_t *der, uint8_t *end)
{
unsigned len, len1;
if (end - der < 2)
xfunc_die();
// if ((der[0] & 0x1f) == 0x1f) /* not single-byte item code? */
// xfunc_die();
len = der[1]; /* maybe it's short len */
if (len >= 0x80) {
/* no, it's long */
if (len == 0x80 || end - der < (int)(len - 0x7e)) {
/* 0x80 is "0 bytes of len", invalid DER: must use short len if can */
/* need 3 or 4 bytes for 81, 82 */
xfunc_die();
}
len1 = der[2]; /* if (len == 0x81) it's "ii 81 xx", fetch xx */
if (len > 0x82) {
/* >0x82 is "3+ bytes of len", should not happen realistically */
xfunc_die();
}
if (len == 0x82) { /* it's "ii 82 xx yy" */
len1 = 0x100*len1 + der[3];
der += 1; /* skip [yy] */
}
der += 1; /* skip [xx] */
len = len1;
// if (len < 0x80)
// xfunc_die(); /* invalid DER: must use short len if can */
}
der += 2; /* skip [code]+[1byte] */
if (end - der < (int)len)
xfunc_die();
*bodyp = der;
return len;
}
static uint8_t *enter_der_item(uint8_t *der, uint8_t **endp)
{
uint8_t *new_der;
unsigned len = get_der_len(&new_der, der, *endp);
dbg_der("entered der @%p:0x%02x len:%u inner_byte @%p:0x%02x\n", der, der[0], len, new_der, new_der[0]);
/* Move "end" position to cover only this item */
*endp = new_der + len;
return new_der;
}
static uint8_t *skip_der_item(uint8_t *der, uint8_t *end)
{
uint8_t *new_der;
unsigned len = get_der_len(&new_der, der, end);
/* Skip body */
new_der += len;
dbg_der("skipped der 0x%02x, next byte 0x%02x\n", der[0], new_der[0]);
return new_der;
}
static void der_binary_to_pstm(pstm_int *pstm_n, uint8_t *der, uint8_t *end)
{
uint8_t *bin_ptr;
unsigned len = get_der_len(&bin_ptr, der, end);
dbg_der("binary bytes:%u, first:0x%02x\n", len, bin_ptr[0]);
binary_to_pstm(pstm_n, bin_ptr, len);
}
static void find_key_in_der_cert(tls_state_t *tls, uint8_t *der, int len)
{
/* Certificate is a DER-encoded data structure. Each DER element has a length,
* which makes it easy to skip over large compound elements of any complexity
* without parsing them. Example: partial decode of kernel.org certificate:
* SEQ 0x05ac/1452 bytes (Certificate): 308205ac
* SEQ 0x0494/1172 bytes (tbsCertificate): 30820494
* [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0] 3 bytes: a003
* INTEGER (version): 0201 02
* INTEGER 0x11 bytes (serialNumber): 0211 00 9f85bf664b0cddafca508679501b2be4
* //^^^^^^note: matrixSSL also allows [ASN_CONTEXT_SPECIFIC | ASN_PRIMITIVE | 2] = 0x82 type
* SEQ 0x0d bytes (signatureAlgo): 300d
* OID 9 bytes: 0609 2a864886f70d01010b (OID_SHA256_RSA_SIG 42.134.72.134.247.13.1.1.11)
* NULL: 0500
* SEQ 0x5f bytes (issuer): 305f
* SET 11 bytes: 310b
* SEQ 9 bytes: 3009
* OID 3 bytes: 0603 550406
* Printable string "FR": 1302 4652
* SET 14 bytes: 310e
* SEQ 12 bytes: 300c
* OID 3 bytes: 0603 550408
* Printable string "Paris": 1305 5061726973
* SET 14 bytes: 310e
* SEQ 12 bytes: 300c
* OID 3 bytes: 0603 550407
* Printable string "Paris": 1305 5061726973
* SET 14 bytes: 310e
* SEQ 12 bytes: 300c
* OID 3 bytes: 0603 55040a
* Printable string "Gandi": 1305 47616e6469
* SET 32 bytes: 3120
* SEQ 30 bytes: 301e
* OID 3 bytes: 0603 550403
* Printable string "Gandi Standard SSL CA 2": 1317 47616e6469205374616e646172642053534c2043412032
* SEQ 30 bytes (validity): 301e
* TIME "161011000000Z": 170d 3136313031313030303030305a
* TIME "191011235959Z": 170d 3139313031313233353935395a
* SEQ 0x5b/91 bytes (subject): 305b //I did not decode this
* 3121301f060355040b1318446f6d61696e20436f
* 6e74726f6c2056616c6964617465643121301f06
* 0355040b1318506f73697469766553534c204d75
* 6c74692d446f6d61696e31133011060355040313
* 0a6b65726e656c2e6f7267
* SEQ 0x01a2/418 bytes (subjectPublicKeyInfo): 308201a2
* SEQ 13 bytes (algorithm): 300d
* OID 9 bytes: 0609 2a864886f70d010101 (OID_RSA_KEY_ALG 42.134.72.134.247.13.1.1.1)
* NULL: 0500
* BITSTRING 0x018f/399 bytes (publicKey): 0382018f
* ????: 00
* //after the zero byte, it appears key itself uses DER encoding:
* SEQ 0x018a/394 bytes: 3082018a
* INTEGER 0x0181/385 bytes (modulus): 02820181
* 00b1ab2fc727a3bef76780c9349bf3
* ...24 more blocks of 15 bytes each...
* 90e895291c6bc8693b65
* INTEGER 3 bytes (exponent): 0203 010001
* [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0x3] 0x01e5 bytes (X509v3 extensions): a38201e5
* SEQ 0x01e1 bytes: 308201e1
* ...
* Certificate is a sequence of three elements:
* tbsCertificate (SEQ)
* signatureAlgorithm (AlgorithmIdentifier)
* signatureValue (BIT STRING)
*
* In turn, tbsCertificate is a sequence of:
* version
* serialNumber
* signatureAlgo (AlgorithmIdentifier)
* issuer (Name, has complex structure)
* validity (Validity, SEQ of two Times)
* subject (Name)
* subjectPublicKeyInfo (SEQ)
* ...
*
* subjectPublicKeyInfo is a sequence of:
* algorithm (AlgorithmIdentifier)
* publicKey (BIT STRING)
*
* We need Certificate.tbsCertificate.subjectPublicKeyInfo.publicKey
*
* Example of an ECDSA key:
* SEQ 0x59 bytes (subjectPublicKeyInfo): 3059
* SEQ 0x13 bytes (algorithm): 3013
* OID 7 bytes: 0607 2a8648ce3d0201 (OID_ECDSA_KEY_ALG 42.134.72.206.61.2.1)
* OID 8 bytes: 0608 2a8648ce3d030107 (OID_EC_prime256v1 42.134.72.206.61.3.1.7)
* BITSTRING 0x42 bytes (publicKey): 0342
* 0004 53af f65e 50cc 7959 7e29 0171 c75c
* 7335 e07d f45b 9750 b797 3a38 aebb 2ac6
* 8329 2748 e77e 41cb d482 2ce6 05ec a058
* f3ab d561 2f4c d845 9ad3 7252 e3de bd3b
* 9012
*/
uint8_t *end = der + len;
/* enter "Certificate" item: [der, end) will be only Cert */
der = enter_der_item(der, &end);
/* enter "tbsCertificate" item: [der, end) will be only tbsCert */
der = enter_der_item(der, &end);
/*
* Skip version field only if it is present. For a v1 certificate, the
* version field won't be present since v1 is the default value for the
* version field and fields with default values should be omitted (see
* RFC 5280 sections 4.1 and 4.1.2.1). If the version field is present
* it will have a tag class of 2 (context-specific), bit 6 as 1
* (constructed), and a tag number of 0 (see ITU-T X.690 sections 8.1.2
* and 8.14).
*/
/* bits 7-6: 10 */
/* bit 5: 1 */
/* bits 4-0: 00000 */
if (der[0] == 0xa0)
der = skip_der_item(der, end); /* version */
/* skip up to subjectPublicKeyInfo */
der = skip_der_item(der, end); /* serialNumber */
der = skip_der_item(der, end); /* signatureAlgo */
der = skip_der_item(der, end); /* issuer */
der = skip_der_item(der, end); /* validity */
der = skip_der_item(der, end); /* subject */
/* enter subjectPublicKeyInfo */
der = enter_der_item(der, &end);
{ /* check subjectPublicKeyInfo.algorithm */
static const uint8_t OID_RSA_KEY_ALG[] ALIGN1 = {
0x30,0x0d, // SEQ 13 bytes
0x06,0x09, 0x2a,0x86,0x48,0x86,0xf7,0x0d,0x01,0x01,0x01, //OID_RSA_KEY_ALG 42.134.72.134.247.13.1.1.1
//0x05,0x00, // NULL
};
static const uint8_t OID_ECDSA_KEY_ALG[] ALIGN1 = {
0x30,0x13, // SEQ 0x13 bytes
0x06,0x07, 0x2a,0x86,0x48,0xce,0x3d,0x02,0x01, //OID_ECDSA_KEY_ALG 42.134.72.206.61.2.1
//allow any curve code for now...
// 0x06,0x08, 0x2a,0x86,0x48,0xce,0x3d,0x03,0x01,0x07, //OID_EC_prime256v1 42.134.72.206.61.3.1.7
//RFC 3279:
//42.134.72.206.61.3 is ellipticCurve
//42.134.72.206.61.3.0 is c-TwoCurve
//42.134.72.206.61.3.1 is primeCurve
//42.134.72.206.61.3.1.7 is curve_secp256r1
};
if (memcmp(der, OID_RSA_KEY_ALG, sizeof(OID_RSA_KEY_ALG)) == 0) {
dbg("RSA key\n");
tls->flags |= GOT_CERT_RSA_KEY_ALG;
} else
if (memcmp(der, OID_ECDSA_KEY_ALG, sizeof(OID_ECDSA_KEY_ALG)) == 0) {
dbg("ECDSA key\n");
//UNUSED: tls->flags |= GOT_CERT_ECDSA_KEY_ALG;
} else
bb_simple_error_msg_and_die("not RSA or ECDSA cert");
}
if (tls->flags & GOT_CERT_RSA_KEY_ALG) {
/* parse RSA key: */
//based on getAsnRsaPubKey(), pkcs1ParsePrivBin() is also of note
/* skip subjectPublicKeyInfo.algorithm */
der = skip_der_item(der, end);
/* enter subjectPublicKeyInfo.publicKey */
//die_if_not_this_der_type(der, end, 0x03); /* must be BITSTRING */
der = enter_der_item(der, &end);
dbg("key bytes:%u, first:0x%02x\n", (int)(end - der), der[0]);
if (end - der < 14)
xfunc_die();
/* example format:
* ignore bits: 00
* SEQ 0x018a/394 bytes: 3082018a
* INTEGER 0x0181/385 bytes (modulus): 02820181 XX...XXX
* INTEGER 3 bytes (exponent): 0203 010001
*/
if (*der != 0) /* "ignore bits", should be 0 */
xfunc_die();
der++;
der = enter_der_item(der, &end); /* enter SEQ */
/* memset(tls->hsd->server_rsa_pub_key, 0, sizeof(tls->hsd->server_rsa_pub_key)); - already is */
der_binary_to_pstm(&tls->hsd->server_rsa_pub_key.N, der, end); /* modulus */
der = skip_der_item(der, end);
der_binary_to_pstm(&tls->hsd->server_rsa_pub_key.e, der, end); /* exponent */
tls->hsd->server_rsa_pub_key.size = pstm_unsigned_bin_size(&tls->hsd->server_rsa_pub_key.N);
dbg("server_rsa_pub_key.size:%d\n", tls->hsd->server_rsa_pub_key.size);
}
/* else: ECDSA key. It is not used for generating encryption keys,
* it is used only to sign the EC public key (which comes in ServerKey message).
* Since we do not verify cert validity, verifying signature on EC public key
* wouldn't add any security. Thus, we do nothing here.
*/
}
/*
* TLS Handshake routines
*/
static int tls_xread_handshake_block(tls_state_t *tls, int min_len)
{
struct record_hdr *xhdr;
int len = tls_xread_record(tls, "handshake record");
xhdr = (void*)tls->inbuf;
if (len < min_len
|| xhdr->type != RECORD_TYPE_HANDSHAKE
) {
bad_record_die(tls, "handshake record", len);
}
dbg("got HANDSHAKE\n");
return len;
}
static ALWAYS_INLINE void fill_handshake_record_hdr(void *buf, unsigned type, unsigned len)
{
struct handshake_hdr {
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
} *h = buf;
len -= 4;
h->type = type;
h->len24_hi = len >> 16;
h->len24_mid = len >> 8;
h->len24_lo = len & 0xff;
}
static void send_client_hello_and_alloc_hsd(tls_state_t *tls, const char *sni)
{
#define NUM_CIPHERS (7 + 6 * ENABLE_FEATURE_TLS_SHA1 + ALLOW_RSA_NULL_SHA256)
static const uint8_t ciphers[] = {
0x00,2 + NUM_CIPHERS*2, //len16_be
0x00,0xFF, //not a cipher - TLS_EMPTY_RENEGOTIATION_INFO_SCSV
/* ^^^^^^ RFC 5746 Renegotiation Indication Extension - some servers will refuse to work with us otherwise */
#if ENABLE_FEATURE_TLS_SHA1
0xC0,0x09, // 1 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA - ok: wget https://is.gd/
0xC0,0x0A, // 2 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA - ok: wget https://is.gd/
0xC0,0x13, // 3 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA
0xC0,0x14, // 4 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES256-SHA (might fail with older openssl)
// 0xC0,0x18, // TLS_ECDH_anon_WITH_AES_128_CBC_SHA
// 0xC0,0x19, // TLS_ECDH_anon_WITH_AES_256_CBC_SHA
#endif
0xC0,0x23, // 5 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 - ok: wget https://is.gd/
// 0xC0,0x24, // TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
0xC0,0x27, // 6 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA256
// 0xC0,0x28, // TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
0xC0,0x2B, // 7 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 - ok: wget https://is.gd/
// 0xC0,0x2C, // TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 - wget https://is.gd/: "TLS error from peer (alert code 20): bad MAC"
//TODO: GCM_SHA384 ciphers can be supported, only need sha384-based PRF?
0xC0,0x2F, // 8 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-GCM-SHA256
// 0xC0,0x30, // TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 - openssl s_server ... -cipher ECDHE-RSA-AES256-GCM-SHA384: "decryption failed or bad record mac"
//possibly these too:
#if ENABLE_FEATURE_TLS_SHA1
// 0xC0,0x35, // TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA
// 0xC0,0x36, // TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA
#endif
// 0xC0,0x37, // TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256
// 0xC0,0x38, // TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
#if ENABLE_FEATURE_TLS_SHA1
0x00,0x2F, // 9 TLS_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher AES128-SHA
0x00,0x35, //10 TLS_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher AES256-SHA
#endif
0x00,0x3C, //11 TLS_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher AES128-SHA256
0x00,0x3D, //12 TLS_RSA_WITH_AES_256_CBC_SHA256 - ok: openssl s_server ... -cipher AES256-SHA256
0x00,0x9C, //13 TLS_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher AES128-GCM-SHA256
// 0x00,0x9D, // TLS_RSA_WITH_AES_256_GCM_SHA384 - openssl s_server ... -cipher AES256-GCM-SHA384: "decryption failed or bad record mac"
#if ALLOW_RSA_NULL_SHA256
0x00,0x3B, // TLS_RSA_WITH_NULL_SHA256
#endif
0x01,0x00, //not a cipher - comprtypes_len, comprtype
};
static const uint8_t supported_groups[] = {
0x00,0x0a, //extension_type: "supported_groups"
0x00,0x06, //ext len
0x00,0x04, //list len
0x00,0x17, //curve_secp256r1
//0x00,0x18, //curve_secp384r1
//0x00,0x19, //curve_secp521r1
0x00,0x1d, //curve_x25519 (RFC 7748)
//0x00,0x1e, //curve_x448 (RFC 7748)
};
//static const uint8_t signature_algorithms[] = {
// 000d
// 0020
// 001e
// 0601 0602 0603 0501 0502 0503 0401 0402 0403 0301 0302 0303 0201 0202 0203
//};
struct client_hello {
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
uint8_t proto_maj, proto_min;
uint8_t rand32[32];
uint8_t session_id_len;
/* uint8_t session_id[]; */
uint8_t cipherid_len16_hi, cipherid_len16_lo;
uint8_t cipherid[2 + NUM_CIPHERS*2]; /* actually variable */
uint8_t comprtypes_len;
uint8_t comprtypes[1]; /* actually variable */
/* Extensions (SNI shown):
* hi,lo // len of all extensions
* 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 0014 0401 0403 0501 0503 0601 0603 0301 0303 0201 0203 - signature_algorithms
// wolfssl library sends this option, RFC 7627 (closes a security weakness, some servers may require it. TODO?):
// 0017 0000 - extended master secret
};
struct client_hello *record;
uint8_t *ptr;
int len;
int ext_len;
int sni_len = sni ? strnlen(sni, 127 - 5) : 0;
ext_len = 0;
/* is.gd responds with "handshake failure" to our hello if there's no supported_groups element */
ext_len += sizeof(supported_groups);
if (sni_len)
ext_len += 9 + sni_len;
/* +2 is for "len of all extensions" 2-byte field */
len = sizeof(*record) + 2 + ext_len;
record = tls_get_zeroed_outbuf(tls, 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 */
tls_get_random(record->rand32, sizeof(record->rand32));
if (TLS_DEBUG_FIXED_SECRETS)
memset(record->rand32, 0x11, sizeof(record->rand32));
/* record->session_id_len = 0; - already is */
BUILD_BUG_ON(sizeof(ciphers) != 2 + 2 + NUM_CIPHERS*2 + 2);
memcpy(&record->cipherid_len16_hi, ciphers, sizeof(ciphers));
ptr = (void*)(record + 1);
*ptr++ = ext_len >> 8;
*ptr++ = ext_len;
if (sni_len) {
//ptr[0] = 0; //
//ptr[1] = 0; //extension_type
//ptr[2] = 0; //
ptr[3] = sni_len + 5; //list len
//ptr[4] = 0; //
ptr[5] = sni_len + 3; //len of 1st SNI
//ptr[6] = 0; //name type
//ptr[7] = 0; //
ptr[8] = sni_len; //name len
ptr = mempcpy(&ptr[9], sni, sni_len);
}
memcpy(ptr, supported_groups, sizeof(supported_groups));
tls->hsd = xzalloc(sizeof(*tls->hsd));
/* HANDSHAKE HASH: ^^^ + len if need to save saved_client_hello */
memcpy(tls->hsd->client_and_server_rand32, record->rand32, sizeof(record->rand32));
/* HANDSHAKE HASH:
tls->hsd->saved_client_hello_size = len;
memcpy(tls->hsd->saved_client_hello, record, len);
*/
dbg(">> CLIENT_HELLO\n");
/* Can hash immediately only if we know which MAC hash to use.
* So far we do know: it's sha256:
*/
sha256_begin(&tls->hsd->handshake_hash_ctx);
xwrite_and_update_handshake_hash(tls, len);
/* if this would become infeasible: save tls->hsd->saved_client_hello,
* use "xwrite_handshake_record(tls, len)" here,
* and hash saved_client_hello later.
*/
}
static void get_server_hello(tls_state_t *tls)
{
struct server_hello {
struct record_hdr xhdr;
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
uint8_t proto_maj, proto_min;
uint8_t rand32[32]; /* first 4 bytes are unix time in BE format */
uint8_t session_id_len;
uint8_t session_id[32];
uint8_t cipherid_hi, cipherid_lo;
uint8_t comprtype;
/* extensions may follow, but only those which client offered in its Hello */
};
struct server_hello *hp;
uint8_t *cipherid;
uint8_t cipherid1;
int len, len24;
len = tls_xread_handshake_block(tls, 74 - 32);
hp = (void*)tls->inbuf;
// 74 bytes:
// 02 000046 03|03 58|78|cf|c1 50|a5|49|ee|7e|29|48|71|fe|97|fa|e8|2d|19|87|72|90|84|9d|37|a3|f0|cb|6f|5f|e3|3c|2f |20 |d8|1a|78|96|52|d6|91|01|24|b3|d6|5b|b7|d0|6c|b3|e1|78|4e|3c|95|de|74|a0|ba|eb|a7|3a|ff|bd|a2|bf |00|9c |00|
//SvHl len=70 maj.min unixtime^^^ 28randbytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^ slen sid32bytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cipSel comprSel
if (hp->type != HANDSHAKE_SERVER_HELLO
|| hp->len24_hi != 0
|| hp->len24_mid != 0
/* hp->len24_lo checked later */
|| hp->proto_maj != TLS_MAJ
|| hp->proto_min != TLS_MIN
) {
bad_record_die(tls, "'server hello'", len);
}
cipherid = &hp->cipherid_hi;
len24 = hp->len24_lo;
if (hp->session_id_len != 32) {
if (hp->session_id_len != 0)
bad_record_die(tls, "'server hello'", len);
// session_id_len == 0: no session id
// "The server
// may return an empty session_id to indicate that the session will
// not be cached and therefore cannot be resumed."
cipherid -= 32;
len24 += 32; /* what len would be if session id would be present */
}
if (len24 < 70)
bad_record_die(tls, "'server hello'", len);
dbg("<< SERVER_HELLO\n");
memcpy(tls->hsd->client_and_server_rand32 + 32, hp->rand32, sizeof(hp->rand32));
/* Set up encryption params based on selected cipher */
#if 0
#if ENABLE_FEATURE_TLS_SHA1
0xC0,0x09, // 1 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA - ok: wget https://is.gd/
0xC0,0x0A, // 2 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA - ok: wget https://is.gd/
0xC0,0x13, // 3 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA
0xC0,0x14, // 4 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES256-SHA (might fail with older openssl)
// 0xC0,0x18, // TLS_ECDH_anon_WITH_AES_128_CBC_SHA
// 0xC0,0x19, // TLS_ECDH_anon_WITH_AES_256_CBC_SHA
#endif
0xC0,0x23, // 5 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 - ok: wget https://is.gd/
// 0xC0,0x24, // TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
0xC0,0x27, // 6 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA256
// 0xC0,0x28, // TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
0xC0,0x2B, // 7 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 - ok: wget https://is.gd/
// 0xC0,0x2C, // TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 - wget https://is.gd/: "TLS error from peer (alert code 20): bad MAC"
//TODO: GCM_SHA384 ciphers can be supported, only need sha384-based PRF?
0xC0,0x2F, // 8 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-GCM-SHA256
// 0xC0,0x30, // TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 - openssl s_server ... -cipher ECDHE-RSA-AES256-GCM-SHA384: "decryption failed or bad record mac"
//possibly these too:
#if ENABLE_FEATURE_TLS_SHA1
// 0xC0,0x35, // TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA
// 0xC0,0x36, // TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA
#endif
// 0xC0,0x37, // TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256
// 0xC0,0x38, // TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
#if ENABLE_FEATURE_TLS_SHA1
0x00,0x2F, // 9 TLS_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher AES128-SHA
0x00,0x35, //10 TLS_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher AES256-SHA
#endif
0x00,0x3C, //11 TLS_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher AES128-SHA256
0x00,0x3D, //12 TLS_RSA_WITH_AES_256_CBC_SHA256 - ok: openssl s_server ... -cipher AES256-SHA256
0x00,0x9C, //13 TLS_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher AES128-GCM-SHA256
// 0x00,0x9D, // TLS_RSA_WITH_AES_256_GCM_SHA384 - openssl s_server ... -cipher AES256-GCM-SHA384: "decryption failed or bad record mac"
#if ALLOW_RSA_NULL_SHA256
0x00,0x3B, // TLS_RSA_WITH_NULL_SHA256
#endif
#endif
cipherid1 = cipherid[1];
tls->cipher_id = 0x100 * cipherid[0] + cipherid1;
tls->key_size = AES256_KEYSIZE;
tls->MAC_size = SHA256_OUTSIZE;
/*tls->IV_size = 0; - already is */
if (cipherid[0] == 0xC0) {
/* All C0xx are ECDHE */
tls->flags |= NEED_EC_KEY;
if (cipherid1 & 1) {
/* Odd numbered C0xx use AES128 (even ones use AES256) */
tls->key_size = AES128_KEYSIZE;
}
if (ENABLE_FEATURE_TLS_SHA1 && cipherid1 <= 0x19) {
tls->MAC_size = SHA1_OUTSIZE;
} else
if (cipherid1 >= 0x2B && cipherid1 <= 0x30) {
/* C02B,2C,2F,30 are AES-GCM */
tls->flags |= ENCRYPTION_AESGCM;
tls->MAC_size = 0;
tls->IV_size = 4;
}
} else {
/* All 00xx are RSA */
if ((ENABLE_FEATURE_TLS_SHA1 && cipherid1 == 0x2F)
|| cipherid1 == 0x3C
|| cipherid1 == 0x9C
) {
tls->key_size = AES128_KEYSIZE;
}
if (ENABLE_FEATURE_TLS_SHA1 && cipherid1 <= 0x35) {
tls->MAC_size = SHA1_OUTSIZE;
} else
if (cipherid1 == 0x9C /*|| cipherid1 == 0x9D*/) {
/* 009C,9D are AES-GCM */
tls->flags |= ENCRYPTION_AESGCM;
tls->MAC_size = 0;
tls->IV_size = 4;
}
}
dbg("server chose cipher %04x\n", tls->cipher_id);
dbg("key_size:%u MAC_size:%u IV_size:%u\n", tls->key_size, tls->MAC_size, tls->IV_size);
/* Handshake hash eventually destined to FINISHED record
* is sha256 regardless of cipher
* (at least for all ciphers defined by RFC5246).
* It's not sha1 for AES_128_CBC_SHA - only MAC is sha1, not this hash.
*/
/* HANDSHAKE HASH:
sha256_begin(&tls->hsd->handshake_hash_ctx);
hash_handshake(tls, ">> client hello hash:%s",
tls->hsd->saved_client_hello, tls->hsd->saved_client_hello_size
);
hash_handshake(tls, "<< server hello hash:%s",
tls->inbuf + RECHDR_LEN, len
);
*/
}
static void get_server_cert(tls_state_t *tls)
{
struct record_hdr *xhdr;
uint8_t *certbuf;
int len, len1;
len = tls_xread_handshake_block(tls, 10);
xhdr = (void*)tls->inbuf;
certbuf = (void*)(xhdr + 1);
if (certbuf[0] != HANDSHAKE_CERTIFICATE)
bad_record_die(tls, "certificate", len);
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
len1 = get24be(certbuf + 1);
if (len1 > len - 4) tls_error_die(tls);
len = len1;
len1 = get24be(certbuf + 4);
if (len1 > len - 3) tls_error_die(tls);
len = len1;
len1 = get24be(certbuf + 7);
if (len1 > len - 3) tls_error_die(tls);
len = len1;
if (len)
find_key_in_der_cert(tls, certbuf + 10, len);
}
/* On input, len is known to be >= 4.
* The record is known to be SERVER_KEY_EXCHANGE.
*/
static void process_server_key(tls_state_t *tls, int len)
{
struct record_hdr *xhdr;
uint8_t *keybuf;
int len1;
uint32_t t32;
xhdr = (void*)tls->inbuf;
keybuf = (void*)(xhdr + 1);
//seen from is.gd: it selects curve_x25519:
// 0c 00006e //SERVER_KEY_EXCHANGE, len
// 03 //curve_type: named curve
// 001d //curve_x25519
//server-chosen EC point, and then signed_params
// (RFC 8422: "A hash of the params, with the signature
// appropriate to that hash applied. The private key corresponding
// to the certified public key in the server's Certificate message is
// used for signing.")
//follow. Format unclear/guessed:
// 20 //eccPubKeyLen
// 25511923d73b70dd2f60e66ba2f3fda31a9c25170963c7a3a972e481dbb2835d //eccPubKey (32bytes)
// 0203 //hashSigAlg: 2:SHA1 (4:SHA256 5:SHA384 6:SHA512), 3:ECDSA (1:RSA)
// 0046 //len (16bit)
// 30 44 //SEQ, len
// 02 20 //INTEGER, len
// 2e18e7c2a9badd0a70cd3059a6ab114539b9f5163568911147386cd77ed7c412 //32bytes
//this item ^^^^^ is sometimes 33 bytes (with all container sizes also +1)
// 02 20 //INTEGER, len
// 64523d6216cb94c43c9b20e377d8c52c55be6703fd6730a155930c705eaf3af6 //32bytes
//same about this item ^^^^^
//seen from ftp.openbsd.org
//(which only accepts ECDHE-RSA-AESnnn-GCM-SHAnnn and ECDHE-RSA-CHACHA20-POLY1305 ciphers):
// 0c 000228 //SERVER_KEY_EXCHANGE, len
// 03 //curve_type: named curve
// 001d //curve_x25519
// 20 //eccPubKeyLen
// eef7a15c43b71a4c7eaa48a39369399cc4332e569ec90a83274cc92596705c1a //eccPubKey
// 0401 //hashSigAlg: 4:SHA256, 1:RSA
// 0200 //len
// //0x200 bytes follow
/* Get and verify length */
len1 = get24be(keybuf + 1);
if (len1 > len - 4) tls_error_die(tls);
len = len1;
if (len < (1+2+1+32)) tls_error_die(tls);
keybuf += 4;
#if BB_BIG_ENDIAN
# define _0x03001741 0x03001741
# define _0x03001d20 0x03001d20
#else
# define _0x03001741 0x41170003
# define _0x03001d20 0x201d0003
#endif
move_from_unaligned32(t32, keybuf);
keybuf += 4;
switch (t32) {
case _0x03001d20: //curve_x25519
tls->flags |= GOT_EC_CURVE_X25519;
memcpy(tls->hsd->ecc_pub_key32, keybuf, 32);
break;
case _0x03001741: //curve_secp256r1
/* P256 point can be transmitted odd- or even-compressed
* (first byte is 3 or 2) or uncompressed (4).
*/
if (*keybuf++ != 4)
bb_simple_error_msg_and_die("compressed EC points not supported");
memcpy(tls->hsd->ecc_pub_key32, keybuf, 2 * 32);
break;
default:
bb_error_msg_and_die("elliptic curve is not x25519 or P256: 0x%08x", t32);
}
tls->flags |= GOT_EC_KEY;
dbg("got eccPubKey\n");
}
static void send_empty_client_cert(tls_state_t *tls)
{
struct client_empty_cert {
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
uint8_t cert_chain_len24_hi, cert_chain_len24_mid, cert_chain_len24_lo;
};
struct client_empty_cert *record;
record = tls_get_zeroed_outbuf(tls, sizeof(*record));
//fill_handshake_record_hdr(record, HANDSHAKE_CERTIFICATE, sizeof(*record));
//record->cert_chain_len24_hi = 0;
//record->cert_chain_len24_mid = 0;
//record->cert_chain_len24_lo = 0;
// same as above:
record->type = HANDSHAKE_CERTIFICATE;
record->len24_lo = 3;
dbg(">> CERTIFICATE\n");
xwrite_and_update_handshake_hash(tls, sizeof(*record));
}
static void send_client_key_exchange(tls_state_t *tls)
{
struct client_key_exchange {
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
uint8_t key[2 + 4 * 1024]; // size??
};
//FIXME: better size estimate
struct client_key_exchange *record = tls_get_zeroed_outbuf(tls, sizeof(*record));
uint8_t premaster[RSA_PREMASTER_SIZE > EC_CURVE_KEYSIZE ? RSA_PREMASTER_SIZE : EC_CURVE_KEYSIZE];
int premaster_size;
int len;
if (!(tls->flags & NEED_EC_KEY)) {
/* RSA */
if (!(tls->flags & GOT_CERT_RSA_KEY_ALG))
bb_simple_error_msg("server cert is not RSA");
tls_get_random(premaster, RSA_PREMASTER_SIZE);
if (TLS_DEBUG_FIXED_SECRETS)
memset(premaster, 0x44, RSA_PREMASTER_SIZE);
// 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."
premaster[0] = TLS_MAJ;
premaster[1] = TLS_MIN;
dump_hex("premaster:%s\n", premaster, sizeof(premaster));
len = psRsaEncryptPub(/*pool:*/ NULL,
/* psRsaKey_t* */ &tls->hsd->server_rsa_pub_key,
premaster, /*inlen:*/ RSA_PREMASTER_SIZE,
record->key + 2, sizeof(record->key) - 2,
data_param_ignored
);
/* keylen16 exists for RSA (in TLS, not in SSL), but not for some other key types */
record->key[0] = len >> 8;
record->key[1] = len & 0xff;
len += 2;
premaster_size = RSA_PREMASTER_SIZE;
} else /* ECDHE */
if (tls->flags & GOT_EC_CURVE_X25519) {
/* ECDHE, curve x25519 */
static const uint8_t basepoint9[CURVE25519_KEYSIZE] ALIGN8 = {9};
uint8_t privkey[CURVE25519_KEYSIZE]; //[32]
if (!(tls->flags & GOT_EC_KEY))
bb_simple_error_msg_and_die("server did not provide EC key");
/* Generate random private key, see RFC 7748 */
tls_get_random(privkey, sizeof(privkey));
privkey[0] &= 0xf8;
privkey[CURVE25519_KEYSIZE-1] = ((privkey[CURVE25519_KEYSIZE-1] & 0x7f) | 0x40);
/* Compute public key */
curve25519(record->key + 1, privkey, basepoint9);
/* Compute premaster using peer's public key */
dbg("computing x25519_premaster\n");
curve25519(premaster, privkey, tls->hsd->ecc_pub_key32);
len = CURVE25519_KEYSIZE;
record->key[0] = len;
len++;
premaster_size = CURVE25519_KEYSIZE;
} else {
/* ECDHE, curve P256 */
if (!(tls->flags & GOT_EC_KEY))
bb_simple_error_msg_and_die("server did not provide EC key");
dbg("computing P256_premaster\n");
curve_P256_compute_pubkey_and_premaster(
record->key + 2, premaster,
/*point:*/ tls->hsd->ecc_pub_key32
);
premaster_size = P256_KEYSIZE;
len = 1 + P256_KEYSIZE * 2;
record->key[0] = len;
record->key[1] = 4;
len++;
}
record->type = HANDSHAKE_CLIENT_KEY_EXCHANGE;
/* record->len24_hi = 0; - already is */
record->len24_mid = len >> 8;
record->len24_lo = len & 0xff;
len += 4;
dbg(">> CLIENT_KEY_EXCHANGE\n");
xwrite_and_update_handshake_hash(tls, len);
// RFC 5246
// For all key exchange methods, the same algorithm is used to convert
// the pre_master_secret into the master_secret. The pre_master_secret
// should be deleted from memory once the master_secret has been
// computed.
// master_secret = PRF(pre_master_secret, "master secret",
// ClientHello.random + ServerHello.random)
// [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.
prf_hmac_sha256(/*tls,*/
tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
premaster, premaster_size,
"master secret",
tls->hsd->client_and_server_rand32, sizeof(tls->hsd->client_and_server_rand32)
);
dump_hex("master secret:%s\n", tls->hsd->master_secret, sizeof(tls->hsd->master_secret));
// RFC 5246
// 6.3. Key Calculation
//
// The Record Protocol requires an algorithm to generate keys required
// by the current connection state (see Appendix A.6) from the security
// parameters provided by the handshake protocol.
//
// The master secret is expanded into a sequence of secure bytes, which
// is then split to a client write MAC key, a server write MAC key, a
// client write encryption key, and a server write encryption key. Each
// of these is generated from the byte sequence in that order. Unused
// values are empty. Some AEAD ciphers may additionally require a
// client write IV and a server write IV (see Section 6.2.3.3).
//
// When keys and MAC keys are generated, the master secret is used as an
// entropy source.
//
// To generate the key material, compute
//
// key_block = PRF(SecurityParameters.master_secret,
// "key expansion",
// SecurityParameters.server_random +
// SecurityParameters.client_random);
//
// until enough output has been generated. Then, the key_block is
// partitioned as follows:
//
// client_write_MAC_key[SecurityParameters.mac_key_length]
// server_write_MAC_key[SecurityParameters.mac_key_length]
// client_write_key[SecurityParameters.enc_key_length]
// server_write_key[SecurityParameters.enc_key_length]
// client_write_IV[SecurityParameters.fixed_iv_length]
// server_write_IV[SecurityParameters.fixed_iv_length]
{
uint8_t tmp64[64];
/* make "server_rand32 + client_rand32" */
memcpy(&tmp64[0] , &tls->hsd->client_and_server_rand32[32], 32);
memcpy(&tmp64[32], &tls->hsd->client_and_server_rand32[0] , 32);
prf_hmac_sha256(/*tls,*/
tls->client_write_MAC_key, 2 * (tls->MAC_size + tls->key_size + tls->IV_size),
// also fills:
// server_write_MAC_key[]
// client_write_key[]
// server_write_key[]
// client_write_IV[]
// server_write_IV[]
tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
"key expansion",
tmp64, 64
);
tls->client_write_key = tls->client_write_MAC_key + (2 * tls->MAC_size);
tls->server_write_key = tls->client_write_key + tls->key_size;
tls->client_write_IV = tls->server_write_key + tls->key_size;
tls->server_write_IV = tls->client_write_IV + tls->IV_size;
dump_hex("client_write_MAC_key:%s\n",
tls->client_write_MAC_key, tls->MAC_size
);
dump_hex("client_write_key:%s\n",
tls->client_write_key, tls->key_size
);
dump_hex("client_write_IV:%s\n",
tls->client_write_IV, tls->IV_size
);
aes_setkey(&tls->aes_decrypt, tls->server_write_key, tls->key_size);
aes_setkey(&tls->aes_encrypt, tls->client_write_key, tls->key_size);
{
uint8_t iv[AES_BLOCK_SIZE];
memset(iv, 0, AES_BLOCK_SIZE);
aes_encrypt_one_block(&tls->aes_encrypt, iv, tls->H);
}
}
}
static const uint8_t rec_CHANGE_CIPHER_SPEC[] ALIGN1 = {
RECORD_TYPE_CHANGE_CIPHER_SPEC, TLS_MAJ, TLS_MIN, 00, 01,
01
};
static void send_change_cipher_spec(tls_state_t *tls)
{
dbg(">> CHANGE_CIPHER_SPEC\n");
xwrite(tls->ofd, rec_CHANGE_CIPHER_SPEC, sizeof(rec_CHANGE_CIPHER_SPEC));
}
// 7.4.9. Finished
// A Finished message is always sent immediately after a change
// cipher spec message to verify that the key exchange and
// authentication processes were successful. It is essential that a
// change cipher spec message be received between the other handshake
// messages and the Finished message.
//...
// The Finished message is the first one protected with the just
// negotiated algorithms, keys, and secrets. Recipients of Finished
// messages MUST verify that the contents are correct. Once a side
// has sent its Finished message and received and validated the
// Finished message from its peer, it may begin to send and receive
// application data over the connection.
//...
// struct {
// opaque verify_data[verify_data_length];
// } Finished;
//
// verify_data
// PRF(master_secret, finished_label, Hash(handshake_messages))
// [0..verify_data_length-1];
//
// finished_label
// For Finished messages sent by the client, the string
// "client finished". For Finished messages sent by the server,
// the string "server finished".
//
// Hash denotes a Hash of the handshake messages. For the PRF
// defined in Section 5, the Hash MUST be the Hash used as the basis
// for the PRF. Any cipher suite which defines a different PRF MUST
// also define the Hash to use in the Finished computation.
//
// In previous versions of TLS, the verify_data was always 12 octets
// long. In the current version of TLS, it depends on the cipher
// suite. Any cipher suite which does not explicitly specify
// verify_data_length has a verify_data_length equal to 12. This
// includes all existing cipher suites.
static void send_client_finished(tls_state_t *tls)
{
struct finished {
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
uint8_t prf_result[12];
};
struct finished *record = tls_get_outbuf(tls, sizeof(*record));
uint8_t handshake_hash[TLS_MAX_MAC_SIZE];
unsigned len;
fill_handshake_record_hdr(record, HANDSHAKE_FINISHED, sizeof(*record));
len = sha_end(&tls->hsd->handshake_hash_ctx, handshake_hash);
prf_hmac_sha256(/*tls,*/
record->prf_result, sizeof(record->prf_result),
tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
"client finished",
handshake_hash, len
);
dump_hex("from secret: %s\n", tls->hsd->master_secret, sizeof(tls->hsd->master_secret));
dump_hex("from labelSeed: %s", "client finished", sizeof("client finished")-1);
dump_hex("%s\n", handshake_hash, sizeof(handshake_hash));
dump_hex("=> digest: %s\n", record->prf_result, sizeof(record->prf_result));
dbg(">> FINISHED\n");
xwrite_encrypted(tls, sizeof(*record), RECORD_TYPE_HANDSHAKE);
}
void FAST_FUNC tls_handshake(tls_state_t *tls, const char *sni)
{
// Client RFC 5246 Server
// (*) - optional messages, not always sent
//
// ClientHello ------->
// ServerHello
// Certificate*
// ServerKeyExchange*
// CertificateRequest*
// <------- ServerHelloDone
// Certificate*
// ClientKeyExchange
// CertificateVerify*
// [ChangeCipherSpec]
// Finished ------->
// [ChangeCipherSpec]
// <------- Finished
// Application Data <------> Application Data
int len;
int got_cert_req;
send_client_hello_and_alloc_hsd(tls, sni);
get_server_hello(tls);
// RFC 5246
// The server MUST send a Certificate message whenever the agreed-
// upon key exchange method uses certificates for authentication
// (this includes all key exchange methods defined in this document
// except DH_anon). This message will always immediately follow the
// ServerHello message.
//
// IOW: in practice, Certificate *always* follows.
// (for example, kernel.org does not even accept DH_anon cipher id)
get_server_cert(tls);
len = tls_xread_handshake_block(tls, 4);
if (tls->inbuf[RECHDR_LEN] == HANDSHAKE_SERVER_KEY_EXCHANGE) {
// 459 bytes:
// 0c 00|01|c7 03|00|17|41|04|87|94|2e|2f|68|d0|c9|f4|97|a8|2d|ef|ed|67|ea|c6|f3|b3|56|47|5d|27|b6|bd|ee|70|25|30|5e|b0|8e|f6|21|5a...
//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...
//
// RFC 8422 5.4. Server Key Exchange
// This message is sent when using the ECDHE_ECDSA, ECDHE_RSA, and
// ECDH_anon key exchange algorithms.
// This message is used to convey the server's ephemeral ECDH public key
// (and the corresponding elliptic curve domain parameters) to the
// client.
dbg("<< SERVER_KEY_EXCHANGE len:%u\n", len);
dump_raw_in("<< %s\n", tls->inbuf, RECHDR_LEN + len);
if (tls->flags & NEED_EC_KEY)
process_server_key(tls, len);
// read next handshake block
len = tls_xread_handshake_block(tls, 4);
}
got_cert_req = (tls->inbuf[RECHDR_LEN] == HANDSHAKE_CERTIFICATE_REQUEST);
if (got_cert_req) {
dbg("<< CERTIFICATE_REQUEST\n");
// RFC 5246: "If no suitable certificate is available,
// the client MUST send a certificate message containing no
// certificates. That is, the certificate_list structure has a
// length of zero. ...
// Client certificates are sent using the Certificate structure
// defined in Section 7.4.2."
// (i.e. the same format as server certs)
/*send_empty_client_cert(tls); - WRONG (breaks handshake hash calc) */
/* need to hash _all_ server replies first, up to ServerHelloDone */
len = tls_xread_handshake_block(tls, 4);
}
if (tls->inbuf[RECHDR_LEN] != HANDSHAKE_SERVER_HELLO_DONE) {
bad_record_die(tls, "'server hello done'", len);
}
// 0e 000000 (len:0)
dbg("<< SERVER_HELLO_DONE\n");
if (got_cert_req)
send_empty_client_cert(tls);
send_client_key_exchange(tls);
send_change_cipher_spec(tls);
/* from now on we should send encrypted */
/* tls->write_seq64_be = 0; - already is */
tls->flags |= ENCRYPT_ON_WRITE;
send_client_finished(tls);
/* Get CHANGE_CIPHER_SPEC */
len = tls_xread_record(tls, "switch to encrypted traffic");
if (len != 1 || memcmp(tls->inbuf, rec_CHANGE_CIPHER_SPEC, 6) != 0)
bad_record_die(tls, "switch to encrypted traffic", len);
dbg("<< CHANGE_CIPHER_SPEC\n");
if (ALLOW_RSA_NULL_SHA256
&& tls->cipher_id == TLS_RSA_WITH_NULL_SHA256
) {
tls->min_encrypted_len_on_read = tls->MAC_size;
} else
if (!(tls->flags & ENCRYPTION_AESGCM)) {
unsigned mac_blocks = (unsigned)(TLS_MAC_SIZE(tls) + AES_BLOCK_SIZE-1) / AES_BLOCK_SIZE;
/* all incoming packets now should be encrypted and have
* at least IV + (MAC padded to blocksize):
*/
tls->min_encrypted_len_on_read = AES_BLOCK_SIZE + (mac_blocks * AES_BLOCK_SIZE);
} else {
tls->min_encrypted_len_on_read = 8 + AES_BLOCK_SIZE;
}
dbg("min_encrypted_len_on_read: %u\n", tls->min_encrypted_len_on_read);
/* Get (encrypted) FINISHED from the server */
len = tls_xread_record(tls, "'server finished'");
if (len < 4 || tls->inbuf[RECHDR_LEN] != HANDSHAKE_FINISHED)
bad_record_die(tls, "'server finished'", len);
dbg("<< FINISHED\n");
/* application data can be sent/received */
/* free handshake data */
psRsaKey_clear(&tls->hsd->server_rsa_pub_key);
// if (PARANOIA)
// memset(tls->hsd, 0, tls->hsd->hsd_size);
free(tls->hsd);
tls->hsd = NULL;
}
static void tls_xwrite(tls_state_t *tls, int len)
{
dbg(">> DATA\n");
xwrite_encrypted(tls, len, RECORD_TYPE_APPLICATION_DATA);
}
// To run a test server using openssl:
// openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
// openssl s_server -key key.pem -cert server.pem -debug -tls1_2
//
// Unencryped SHA256 example:
// openssl req -x509 -newkey rsa:$((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 -cipher NULL
// openssl s_client -connect 127.0.0.1:4433 -debug -tls1_2 -cipher NULL-SHA256
void FAST_FUNC tls_run_copy_loop(tls_state_t *tls, unsigned flags)
{
int inbuf_size;
const int INBUF_STEP = 4 * 1024;
struct pollfd pfds[2];
pfds[0].fd = STDIN_FILENO;
pfds[0].events = POLLIN;
pfds[1].fd = tls->ifd;
pfds[1].events = POLLIN;
inbuf_size = INBUF_STEP;
for (;;) {
int nread;
if (safe_poll(pfds, 2, -1) < 0)
bb_simple_perror_msg_and_die("poll");
if (pfds[0].revents) {
void *buf;
dbg("STDIN HAS DATA\n");
buf = tls_get_outbuf(tls, inbuf_size);
nread = safe_read(STDIN_FILENO, buf, inbuf_size);
if (nread < 1) {
/* We'd want to do this: */
/* Close outgoing half-connection so they get EOF,
* but leave incoming alone so we can see response
*/
//shutdown(tls->ofd, SHUT_WR);
/* But TLS has no way to encode this,
* doubt it's ok to do it "raw"
*/
pfds[0].fd = -1;
tls_free_outbuf(tls); /* mem usage optimization */
if (flags & TLSLOOP_EXIT_ON_LOCAL_EOF)
break;
} else {
if (nread == inbuf_size) {
/* TLS has per record overhead, if input comes fast,
* read, encrypt and send bigger chunks
*/
inbuf_size += INBUF_STEP;
if (inbuf_size > TLS_MAX_OUTBUF)
inbuf_size = TLS_MAX_OUTBUF;
}
tls_xwrite(tls, nread);
}
}
if (pfds[1].revents) {
dbg("NETWORK HAS DATA\n");
read_record:
nread = tls_xread_record(tls, "encrypted data");
if (nread < 1) {
/* TLS protocol has no real concept of one-sided shutdowns:
* if we get "TLS EOF" from the peer, writes will fail too
*/
//pfds[1].fd = -1;
//close(STDOUT_FILENO);
//tls_free_inbuf(tls); /* mem usage optimization */
//continue;
break;
}
if (tls->inbuf[0] != RECORD_TYPE_APPLICATION_DATA)
bad_record_die(tls, "encrypted data", nread);
xwrite(STDOUT_FILENO, tls->inbuf + RECHDR_LEN, nread);
/* We may already have a complete next record buffered,
* can process it without network reads (and possible blocking)
*/
if (tls_has_buffered_record(tls))
goto read_record;
}
}
}
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