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-rw-r--r--networking/tls.c643
1 files changed, 643 insertions, 0 deletions
diff --git a/networking/tls.c b/networking/tls.c
new file mode 100644
index 000000000..983ed507d
--- /dev/null
+++ b/networking/tls.c
@@ -0,0 +1,643 @@
+/*
+ * Licensed under GPLv2, see file LICENSE in this source tree.
+ *
+ * Copyright (C) 2017 Denys Vlasenko
+ */
+//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_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 "libbb.h"
+//#include "tls_cryptoapi.h"
+//#include "tls_ciphers.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_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_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
+//#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 transport_hdr {
+ uint8_t type;
+ uint8_t proto_maj, proto_min;
+ uint8_t len16_hi, len16_lo;
+};
+
+typedef struct tls_state {
+ int fd;
+
+ uint8_t *pubkey;
+ int pubkey_len;
+
+ int insize;
+ int tail;
+ // 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:
+ uint8_t inbuf[18*1024];
+} tls_state_t;
+
+static
+tls_state_t *new_tls_state(void)
+{
+ tls_state_t *tls = xzalloc(sizeof(*tls));
+ tls->fd = -1;
+ return tls;
+}
+
+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)
+{
+ 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(struct transport_hdr) && target == sizeof(tls->inbuf)) {
+ struct transport_hdr *xhdr = (void*)tls->inbuf;
+ target = sizeof(*xhdr) + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
+ }
+ /* if total >= target, we have a full packet (and possibly more)... */
+ if (target - total <= 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 = -(target - total);
+ tls->insize = target;
+ target -= sizeof(struct transport_hdr);
+ dbg("got block len:%u\n", target);
+ return target;
+}
+
+static void send_client_hello(tls_state_t *tls)
+{
+ struct client_hello {
+ struct transport_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;
+ 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_mid = (sizeof(hello) - sizeof(hello.xhdr) - 4) >> 8;
+ hello.len24_lo = (sizeof(hello) - sizeof(hello.xhdr) - 4);
+ hello.proto_maj = TLS_MAJ;
+ hello.proto_min = TLS_MIN;
+ //fillrand(hello.rand32, sizeof(hello.rand32));
+ open_read_close("/dev/urandom", hello.rand32, sizeof(hello.rand32));
+ //hello.session_id_len = 0;
+ //hello.cipherid_len16_hi = 0;
+ hello.cipherid_len16_lo = 2;
+ hello.cipherid[0] = CIPHER_ID >> 8;
+ hello.cipherid[1] = CIPHER_ID & 0xff;
+ hello.comprtypes_len = 1;
+ //hello.comprtypes[0] = 0;
+
+ xwrite(tls->fd, &hello, sizeof(hello));
+}
+
+static void get_server_hello_or_die(tls_state_t *tls)
+{
+ struct server_hello {
+ struct transport_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;
+ int len;
+
+ len = xread_tls_block(tls);
+
+ hp = (void*)tls->inbuf;
+ if (len != 74 /* TODO: if we accept extensions, should be < instead of != */
+ || hp->xhdr.type != RECORD_TYPE_HANDSHAKE
+ || hp->xhdr.proto_maj != TLS_MAJ
+ || hp->xhdr.proto_min != TLS_MIN
+ ) {
+ /* example: RECORD_TYPE_ALERT if server can't support our ciphers */
+ tls_error_die(tls);
+ }
+ dbg("got HANDSHAKE\n");
+ // 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");
+}
+
+static unsigned get_der_len(uint8_t **bodyp, uint8_t *der, uint8_t *end)
+{
+ unsigned len;
+
+ 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 (len != 0x82) {
+ /* 0x80 is "0 bytes of len", invalid DER: must use short len if can */
+ /* 0x81 is "1 byte of len", invalid DER */
+ /* >0x82 is "3+ bytes of len", should not happen realistically */
+ xfunc_die();
+ }
+ if (end - der < 4)
+ xfunc_die();
+ /* it's "ii 82 xx yy" */
+ len = 0x100*der[2] + der[3];
+ if (len < 0x80)
+ xfunc_die(); /* invalid DER: must use short len if can */
+
+ der += 2; /* skip [code]+[82]+[2byte_len] */
+ }
+ der += 2; /* skip [code]+[1byte_len] */
+
+ if (end - der < 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 *find_key_in_der_cert(int *key_len, uint8_t *der, int len)
+{
+/* Example: partial decode of kernel.org certificate in DER format.
+ * 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 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.
+ *
+ * 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)
+ *
+ * Essentially, we want 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);
+
+ /* 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);
+
+ /* return a copy */
+ *key_len = end - der;
+ dbg("copying key bytes:%u, first:0x%02x\n", *key_len, der[0]);
+ return xmemdup(der, *key_len);
+}
+
+static void get_server_cert_or_die(tls_state_t *tls)
+{
+ struct transport_hdr *xhdr;
+ uint8_t *certbuf;
+ int len, len1;
+
+ len = xread_tls_block(tls);
+ xhdr = (void*)tls->inbuf;
+ if (len < sizeof(*xhdr) + 10
+ || xhdr->type != RECORD_TYPE_HANDSHAKE
+ || xhdr->proto_maj != TLS_MAJ
+ || xhdr->proto_min != TLS_MIN
+ ) {
+ tls_error_die(tls);
+ }
+ dbg("got HANDSHAKE\n");
+ certbuf = (void*)(xhdr + 1);
+ if (certbuf[0] != HANDSHAKE_CERTIFICATE)
+ tls_error_die(tls);
+ dbg("got CERTIFICATE\n");
+ // 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... (4392 bytes)
+ // 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)
+ tls->pubkey = find_key_in_der_cert(&tls->pubkey_len, certbuf + 10, len);
+}
+
+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);
+#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
+
+ get_server_hello_or_die(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_or_die(tls);
+
+ len = xread_tls_block(tls);
+ /* Next handshake type is not predetermined */
+ switch (tls->inbuf[5]) {
+ case HANDSHAKE_SERVER_KEY_EXCHANGE:
+ //0c 0001c7 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... 459 bytes
+ //SvKey len^^^
+ dbg("got SERVER_KEY_EXCHANGE\n");
+ len = xread_tls_block(tls);
+ break;
+ case HANDSHAKE_CERTIFICATE_REQUEST:
+ dbg("got CERTIFICATE_REQUEST\n");
+ len = xread_tls_block(tls);
+ break;
+ case HANDSHAKE_SERVER_HELLO_DONE:
+ // 0e 000000 (len:0)
+ dbg("got SERVER_HELLO_DONE\n");
+ break;
+ default:
+ tls_error_die(tls);
+ }
+}
+
+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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-30 13:10:23 +0000