emo/busybox
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
busybox/networking/tls.c
Denys Vlasenko 936e83e694 tls: add sha256 hmac and prf code 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2017-01-16 04:25:01 +01:00

1046 lines
36 KiB
C
Raw Blame History

/*
* Copyright (C) 2017 Denys Vlasenko
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//config:config TLS
//config: bool "tls (debugging)"
//config: default n
//applet:IF_TLS(APPLET(tls, BB_DIR_USR_BIN, BB_SUID_DROP))
//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_rsa.o
////kbuild:lib-$(CONFIG_TLS) += tls_ciphers.o
////kbuild:lib-$(CONFIG_TLS) += tls_aes.o
////kbuild:lib-$(CONFIG_TLS) += tls_aes_gcm.o
//usage:#define tls_trivial_usage
//usage: "HOST[:PORT]"
//usage:#define tls_full_usage "\n\n"
#include "tls.h"
#if 1
# define dbg(...) fprintf(stderr, __VA_ARGS__)
#else
# define dbg(...) ((void)0)
#endif
#define RECORD_TYPE_CHANGE_CIPHER_SPEC 20
#define RECORD_TYPE_ALERT 21
#define RECORD_TYPE_HANDSHAKE 22
#define RECORD_TYPE_APPLICATION_DATA 23
#define HANDSHAKE_HELLO_REQUEST 0
#define HANDSHAKE_CLIENT_HELLO 1
#define HANDSHAKE_SERVER_HELLO 2
#define HANDSHAKE_HELLO_VERIFY_REQUEST 3
#define HANDSHAKE_NEW_SESSION_TICKET 4
#define HANDSHAKE_CERTIFICATE 11
#define HANDSHAKE_SERVER_KEY_EXCHANGE 12
#define HANDSHAKE_CERTIFICATE_REQUEST 13
#define HANDSHAKE_SERVER_HELLO_DONE 14
#define HANDSHAKE_CERTIFICATE_VERIFY 15
#define HANDSHAKE_CLIENT_KEY_EXCHANGE 16
#define HANDSHAKE_FINISHED 20
#define SSL_HS_RANDOM_SIZE 32
#define SSL_HS_RSA_PREMASTER_SIZE 48
#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 SSL_RSA_WITH_3DES_EDE_CBC_SHA 0x000A /* 10 */
#define TLS_RSA_WITH_AES_128_CBC_SHA 0x002F /* 47 */
#define TLS_RSA_WITH_AES_256_CBC_SHA 0x0035 /* 53 */
#define TLS_EMPTY_RENEGOTIATION_INFO_SCSV 0x00FF
#define TLS_RSA_WITH_IDEA_CBC_SHA 0x0007 /* 7 */
#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_DHE_RSA_WITH_AES_128_CBC_SHA 0x0033 /* 51 */
#define TLS_DHE_RSA_WITH_AES_256_CBC_SHA 0x0039 /* 57 */
#define TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 0x0067 /* 103 */
#define TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 0x006B /* 107 */
#define TLS_DH_anon_WITH_AES_128_CBC_SHA 0x0034 /* 52 */
#define TLS_DH_anon_WITH_AES_256_CBC_SHA 0x003A /* 58 */
#define TLS_RSA_WITH_AES_128_CBC_SHA256 0x003C /* 60 */
#define TLS_RSA_WITH_AES_256_CBC_SHA256 0x003D /* 61 */
#define TLS_RSA_WITH_SEED_CBC_SHA 0x0096 /* 150 */
#define TLS_PSK_WITH_AES_128_CBC_SHA 0x008C /* 140 */
#define TLS_PSK_WITH_AES_128_CBC_SHA256 0x00AE /* 174 */
#define TLS_PSK_WITH_AES_256_CBC_SHA384 0x00AF /* 175 */
#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_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 /* 49161 */
#define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA 0xC00A /* 49162 */
#define TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA 0xC012 /* 49170 */
#define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA 0xC013 /* 49171 */
#define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA 0xC014 /* 49172 */
#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_ECDSA_WITH_AES_128_CBC_SHA256 0xC023 /* 49187 */
#define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 0xC024 /* 49188 */
#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 /* 49191 */
#define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 0xC028 /* 49192 */
#define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256 0xC029 /* 49193 */
#define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384 0xC02A /* 49194 */
#define TLS_RSA_WITH_AES_128_GCM_SHA256 0x009C /* 156 */
#define TLS_RSA_WITH_AES_256_GCM_SHA384 0x009D /* 157 */
#define TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 0xC02B /* 49195 */
#define TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 0xC02C /* 49196 */
#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 /* 49199 */
#define TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 0xC030 /* 49200 */
#define TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 0xC031 /* 49201 */
#define TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384 0xC032 /* 49202 */
//Tested against kernel.org:
//TLS 1.1
//#define TLS_MAJ 3
//#define TLS_MIN 2
//#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA // ok, recvs SERVER_KEY_EXCHANGE
//TLS 1.2
#define TLS_MAJ 3
#define TLS_MIN 3
//#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
// All GCMs:
//#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 *** select this?
//#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)
//test TLS_RSA_WITH_AES_128_CBC_SHA, in tls 1.2 it's mandated to be always supported
struct record_hdr {
uint8_t type;
uint8_t proto_maj, proto_min;
uint8_t len16_hi, len16_lo;
};
typedef struct tls_state {
int fd;
psRsaKey_t server_rsa_pub_key;
sha256_ctx_t handshake_sha256_ctx;
uint8_t client_and_server_rand32[2 * 32];
uint8_t master_secret[48];
// 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.
//
// Since our buffer also contains 5-byte headers, make it a bit bigger:
int insize;
int tail;
uint8_t inbuf[18*1024];
} tls_state_t;
void tls_get_random(void *buf, unsigned len)
{
if (len != open_read_close("/dev/urandom", buf, len))
xfunc_die();
}
static
tls_state_t *new_tls_state(void)
{
tls_state_t *tls = xzalloc(sizeof(*tls));
tls->fd = -1;
sha256_begin(&tls->handshake_sha256_ctx);
return tls;
}
static void xwrite_and_hash(tls_state_t *tls, const void *buf, unsigned size)
{
xwrite(tls->fd, buf, size);
/* hash does not include record headers */
if (size > 5)
sha256_hash(&tls->handshake_sha256_ctx, (uint8_t*)buf + 5, size - 5);
}
static unsigned get24be(const uint8_t *p)
{
return 0x100*(0x100*p[0] + p[1]) + p[2];
}
static void dump(const void *vp, int len)
{
char hexbuf[32 * 1024 + 4];
const uint8_t *p = vp;
while (len > 0) {
unsigned xhdr_len;
if (len < 5) {
bin2hex(hexbuf, (void*)p, len)[0] = '\0';
dbg("< |%s|\n", hexbuf);
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 += 5;
len -= 5;
if (len >= 4 && p[-5] == RECORD_TYPE_HANDSHAKE) {
unsigned len24 = get24be(p + 1);
dbg(" type:%u len24:%u", p[0], len24);
}
if (xhdr_len > len)
xhdr_len = len;
bin2hex(hexbuf, (void*)p, xhdr_len)[0] = '\0';
dbg(" |%s|\n", hexbuf);
p += xhdr_len;
len -= xhdr_len;
}
}
static void tls_error_die(tls_state_t *tls)
{
dump(tls->inbuf, tls->insize + tls->tail);
xfunc_die();
}
static int xread_tls_block(tls_state_t *tls)
{
struct record_hdr *xhdr;
int len;
int total;
int target;
dbg("insize:%u tail:%u\n", tls->insize, tls->tail);
memmove(tls->inbuf, tls->inbuf + tls->insize, tls->tail);
errno = 0;
total = tls->tail;
target = sizeof(tls->inbuf);
for (;;) {
if (total >= sizeof(*xhdr) && target == sizeof(tls->inbuf)) {
xhdr = (void*)tls->inbuf;
target = sizeof(*xhdr) + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
if (target >= sizeof(tls->inbuf)) {
/* malformed input (too long): yell and die */
tls->tail = 0;
tls->insize = total;
tls_error_die(tls);
}
// can also check type/proto_maj/proto_min here
}
/* if total >= target, we have a full packet (and possibly more)... */
if (total - target >= 0)
break;
len = safe_read(tls->fd, tls->inbuf + total, sizeof(tls->inbuf) - total);
if (len <= 0)
bb_perror_msg_and_die("short read");
total += len;
}
tls->tail = total - target;
tls->insize = target;
target -= sizeof(*xhdr);
dbg("got block len:%u\n", target);
return target;
}
static int xread_tls_handshake_block(tls_state_t *tls, int min_len)
{
struct record_hdr *xhdr;
int len = xread_tls_block(tls);
xhdr = (void*)tls->inbuf;
if (len < min_len
|| xhdr->type != RECORD_TYPE_HANDSHAKE
|| xhdr->proto_maj != TLS_MAJ
|| xhdr->proto_min != TLS_MIN
) {
tls_error_die(tls);
}
dbg("got HANDSHAKE\n");
return len;
}
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 */
if (end - der < (int)(len - 0x7e)) /* need 3 or 4 bytes for 81, 82 */
xfunc_die();
len1 = der[2];
if (len == 0x81) {
/* it's "ii 81 xx" */
} else if (len == 0x82) {
/* it's "ii 82 xx yy" */
len1 = 0x100*len1 + der[3];
der += 1; /* skip [yy] */
} else {
/* 0x80 is "0 bytes of len", invalid DER: must use short len if can */
/* >0x82 is "3+ bytes of len", should not happen realistically */
xfunc_die();
}
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("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("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("binary bytes:%u, first:0x%02x\n", len, bin_ptr[0]);
pstm_init_for_read_unsigned_bin(/*pool:*/ NULL, pstm_n, len);
pstm_read_unsigned_bin(pstm_n, bin_ptr, len);
//return bin + 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
*/
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 up to subjectPublicKeyInfo */
der = skip_der_item(der, end); /* version */
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 expected[] = {
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
};
if (memcmp(der, expected, sizeof(expected)) != 0)
bb_error_msg_and_die("not RSA key");
}
/* 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);
/* parse RSA key: */
//based on getAsnRsaPubKey(), pkcs1ParsePrivBin() is also of note
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->server_rsa_pub_key, 0, sizeof(tls->server_rsa_pub_key));
der_binary_to_pstm(&tls->server_rsa_pub_key.N, der, end); /* modulus */
der = skip_der_item(der, end);
der_binary_to_pstm(&tls->server_rsa_pub_key.e, der, end); /* exponent */
tls->server_rsa_pub_key.size = pstm_unsigned_bin_size(&tls->server_rsa_pub_key.N);
dbg("server_rsa_pub_key.size:%d\n", tls->server_rsa_pub_key.size);
}
enum {
SHA256_INSIZE = 64,
SHA256_OUTSIZE = 32,
};
static void hash_sha256(uint8_t out[SHA256_OUTSIZE], const void *data, unsigned size)
{
sha256_ctx_t ctx;
sha256_begin(&ctx);
sha256_hash(&ctx, data, size);
sha256_end(&ctx, out);
}
// 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.
static void hmac_sha256_precomputed_v(uint8_t out[SHA256_OUTSIZE],
sha256_ctx_t *hashed_key_xor_ipad,
sha256_ctx_t *hashed_key_xor_opad,
va_list va)
{
uint8_t *text;
/* hashed_key_xor_ipad contains unclosed "H((key XOR ipad) +" state */
/* 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);
sha256_hash(hashed_key_xor_ipad, text, text_size);
}
sha256_end(hashed_key_xor_ipad, out);
/* out = H((key XOR opad) + out) */
sha256_hash(hashed_key_xor_opad, out, SHA256_OUTSIZE);
sha256_end(hashed_key_xor_opad, out);
}
static void hmac_sha256(uint8_t out[SHA256_OUTSIZE], uint8_t *key, unsigned key_size, ...)
{
sha256_ctx_t hashed_key_xor_ipad;
sha256_ctx_t hashed_key_xor_opad;
uint8_t key_xor_ipad[SHA256_INSIZE];
uint8_t key_xor_opad[SHA256_INSIZE];
uint8_t tempkey[SHA256_OUTSIZE];
va_list va;
int i;
va_start(va, key_size);
// "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 > SHA256_INSIZE) {
hash_sha256(tempkey, key, key_size);
key = tempkey;
key_size = SHA256_OUTSIZE;
}
for (i = 0; i < key_size; i++) {
key_xor_ipad[i] = key[i] ^ 0x36;
key_xor_opad[i] = key[i] ^ 0x5c;
}
for (; i < SHA256_INSIZE; i++) {
key_xor_ipad[i] = 0x36;
key_xor_opad[i] = 0x5c;
}
sha256_begin(&hashed_key_xor_ipad);
sha256_hash(&hashed_key_xor_ipad, key_xor_ipad, SHA256_INSIZE);
sha256_begin(&hashed_key_xor_opad);
sha256_hash(&hashed_key_xor_opad, key_xor_opad, SHA256_INSIZE);
hmac_sha256_precomputed_v(out, &hashed_key_xor_ipad, &hashed_key_xor_opad, va);
va_end(va);
}
// 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.
//...
// 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.
static void tls_prf_hmac_sha256(
uint8_t *outbuf, unsigned outbuf_size,
uint8_t *secret, unsigned secret_size,
const char *label,
uint8_t *seed, unsigned seed_size)
{
uint8_t a[SHA256_OUTSIZE];
uint8_t *out_p = outbuf;
unsigned label_size = strlen(label);
/* In P_hash() calculation, "seed" is "label + seed": */
#define SEED label, label_size, seed, seed_size
#define SECRET secret, secret_size
#define A a, (int)(sizeof(a))
/* A(1) = HMAC_hash(secret, seed) */
hmac_sha256(a, SECRET, SEED, NULL);
for(;;) {
/* HMAC_hash(secret, A(1) + seed) */
if (outbuf_size <= SHA256_OUTSIZE) {
/* Last, possibly incomplete, block */
/* (use a[] as temp buffer) */
hmac_sha256(a, SECRET, A, SEED, NULL);
memcpy(out_p, a, outbuf_size);
return;
}
/* Not last block. Store directly to result buffer */
hmac_sha256(out_p, SECRET, A, SEED, NULL);
out_p += SHA256_OUTSIZE;
outbuf_size -= SHA256_OUTSIZE;
/* A(2) = HMAC_hash(secret, A(1)) */
hmac_sha256(a, SECRET, A, NULL);
}
#undef A
#undef SECRET
#undef SEED
}
/*
* TLS Handshake routines
*/
static void send_client_hello(tls_state_t *tls)
{
struct client_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];
uint8_t session_id_len;
/* uint8_t session_id[]; */
uint8_t cipherid_len16_hi, cipherid_len16_lo;
uint8_t cipherid[2 * 1]; /* actually variable */
uint8_t comprtypes_len;
uint8_t comprtypes[1]; /* actually variable */
};
struct client_hello hello;
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;
xwrite_and_hash(tls, &hello, sizeof(hello));
memcpy(tls->client_and_server_rand32, hello.rand32, sizeof(hello.rand32));
#if 0 /* dump */
for (;;) {
uint8_t buf[16*1024];
sleep(2);
len = recv(tls->fd, buf, sizeof(buf), 0); //MSG_DONTWAIT);
if (len < 0) {
if (errno == EAGAIN)
continue;
bb_perror_msg_and_die("recv");
}
if (len == 0)
break;
dump(buf, len);
}
#endif
}
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;
xread_tls_handshake_block(tls, 74);
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 != 70
|| hp->proto_maj != TLS_MAJ
|| hp->proto_min != TLS_MIN
|| hp->session_id_len != 32
|| hp->cipherid_hi != (CIPHER_ID >> 8)
|| hp->cipherid_lo != (CIPHER_ID & 0xff)
|| hp->comprtype != 0
) {
tls_error_die(tls);
}
dbg("got SERVER_HELLO\n");
memcpy(tls->client_and_server_rand32 + 32, hp->rand32, sizeof(hp->rand32));
}
static void get_server_cert(tls_state_t *tls)
{
struct record_hdr *xhdr;
uint8_t *certbuf;
int len, len1;
len = xread_tls_handshake_block(tls, 10);
xhdr = (void*)tls->inbuf;
certbuf = (void*)(xhdr + 1);
if (certbuf[0] != HANDSHAKE_CERTIFICATE)
tls_error_die(tls);
dbg("got 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);
}
static void send_client_key_exchange(tls_state_t *tls)
{
struct client_key_exchange {
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
uint8_t key[384]; // size??
};
struct client_key_exchange record;
uint8_t rsa_premaster[SSL_HS_RSA_PREMASTER_SIZE];
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;
record.type = HANDSHAKE_CLIENT_KEY_EXCHANGE;
//record.len24_hi = 0;
record.len24_mid = (sizeof(record) - sizeof(record.xhdr) - 4) >> 8;
record.len24_lo = (sizeof(record) - sizeof(record.xhdr) - 4) & 0xff;
record.keylen16_hi = (sizeof(record) - sizeof(record.xhdr) - 6) >> 8;
record.keylen16_lo = (sizeof(record) - sizeof(record.xhdr) - 6) & 0xff;
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."
rsa_premaster[0] = TLS_MAJ;
rsa_premaster[1] = TLS_MIN;
psRsaEncryptPub(/*pool:*/ NULL,
/* psRsaKey_t* */ &tls->server_rsa_pub_key,
rsa_premaster, /*inlen:*/ sizeof(rsa_premaster),
record.key, sizeof(record.key),
data_param_ignored
);
xwrite_and_hash(tls, &record, sizeof(record));
// 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.
tls_prf_hmac_sha256(tls->master_secret, sizeof(tls->master_secret),
rsa_premaster, sizeof(rsa_premaster),
"master secret",
tls->client_and_server_rand32, sizeof(tls->client_and_server_rand32)
);
}
static void send_change_cipher_spec(tls_state_t *tls)
{
static const uint8_t rec[] = {
RECORD_TYPE_CHANGE_CIPHER_SPEC, TLS_MAJ, TLS_MIN, 00, 01,
01
};
/* Not "xwrite_and_hash": this is not a handshake message */
xwrite(tls->fd, rec, sizeof(rec));
}
static void send_client_finished(tls_state_t *tls)
{
// 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.
struct client_finished {
struct record_hdr xhdr;
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
uint8_t prf_result[12];
};
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;
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),
tls->master_secret, sizeof(tls->master_secret),
"client finished",
handshake_hash, sizeof(handshake_hash)
);
//(1) TODO: well, this should be encrypted on send, really.
//(2) do we really need to also hash it?
xwrite_and_hash(tls, &record, sizeof(record));
}
static void get_change_cipher_spec(tls_state_t *tls)
{
tls->fd = 0;
}
static void get_server_finished(tls_state_t *tls)
{
tls->fd = 0;
}
static void tls_handshake(tls_state_t *tls)
{
// 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;
send_client_hello(tls);
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 = xread_tls_handshake_block(tls, 4);
if (tls->inbuf[5] == 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...
dbg("got SERVER_KEY_EXCHANGE len:%u\n", len);
//need to save it
xread_tls_handshake_block(tls, 4);
}
// if (tls->inbuf[5] == HANDSHAKE_CERTIFICATE_REQUEST) {
// dbg("got 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
// 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)
// xread_tls_handshake_block(tls, 4);
// }
if (tls->inbuf[5] == HANDSHAKE_SERVER_HELLO_DONE) {
// 0e 000000 (len:0)
dbg("got SERVER_HELLO_DONE\n");
send_client_key_exchange(tls);
send_change_cipher_spec(tls);
//we now should be able to send encrypted... as soon as we grok AES.
send_client_finished(tls);
get_change_cipher_spec(tls);
get_server_finished(tls);
//we now should receive encrypted, and application data can be sent/received
} else {
tls_error_die(tls);
}
}
// To run a test server using openssl:
// openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1
// openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
int tls_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int tls_main(int argc UNUSED_PARAM, char **argv)
{
tls_state_t *tls;
len_and_sockaddr *lsa;
int fd;
// INIT_G();
// getopt32(argv, "myopts")
if (!argv[1])
bb_show_usage();
lsa = xhost2sockaddr(argv[1], 443);
fd = xconnect_stream(lsa);
tls = new_tls_state();
tls->fd = fd;
tls_handshake(tls);
return EXIT_SUCCESS;
}
Reference in New Issue View Git Blame Copy Permalink