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drawterm/libsec/tlshand.c
Russ Cox 934846f35c a
2005-08-08 12:50:13 +00:00

2292 lines
53 KiB
C
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#include <u.h>
#include <libc.h>
#include <bio.h>
#include <auth.h>
#include <mp.h>
#include <libsec.h>
// The main groups of functions are:
// client/server - main handshake protocol definition
// message functions - formating handshake messages
// cipher choices - catalog of digest and encrypt algorithms
// security functions - PKCS#1, sslHMAC, session keygen
// general utility functions - malloc, serialization
// The handshake protocol builds on the TLS/SSL3 record layer protocol,
// which is implemented in kernel device #a. See also /lib/rfc/rfc2246.
enum {
TLSFinishedLen = 12,
SSL3FinishedLen = MD5dlen+SHA1dlen,
MaxKeyData = 104, // amount of secret we may need
MaxChunk = 1<<14,
RandomSize = 32,
SidSize = 32,
MasterSecretSize = 48,
AQueue = 0,
AFlush = 1,
};
typedef struct TlsSec TlsSec;
typedef struct Bytes{
int len;
uchar data[1]; // [len]
} Bytes;
typedef struct Ints{
int len;
int data[1]; // [len]
} Ints;
typedef struct Algs{
char *enc;
char *digest;
int nsecret;
int tlsid;
int ok;
} Algs;
typedef struct Finished{
uchar verify[SSL3FinishedLen];
int n;
} Finished;
typedef struct TlsConnection{
TlsSec *sec; // security management goo
int hand, ctl; // record layer file descriptors
int erred; // set when tlsError called
int (*trace)(char*fmt, ...); // for debugging
int version; // protocol we are speaking
int verset; // version has been set
int ver2hi; // server got a version 2 hello
int isClient; // is this the client or server?
Bytes *sid; // SessionID
Bytes *cert; // only last - no chain
Lock statelk;
int state; // must be set using setstate
// input buffer for handshake messages
uchar buf[MaxChunk+2048];
uchar *rp, *ep;
uchar crandom[RandomSize]; // client random
uchar srandom[RandomSize]; // server random
int clientVersion; // version in ClientHello
char *digest; // name of digest algorithm to use
char *enc; // name of encryption algorithm to use
int nsecret; // amount of secret data to init keys
// for finished messages
MD5state hsmd5; // handshake hash
SHAstate hssha1; // handshake hash
Finished finished;
} TlsConnection;
typedef struct Msg{
int tag;
union {
struct {
int version;
uchar random[RandomSize];
Bytes* sid;
Ints* ciphers;
Bytes* compressors;
} clientHello;
struct {
int version;
uchar random[RandomSize];
Bytes* sid;
int cipher;
int compressor;
} serverHello;
struct {
int ncert;
Bytes **certs;
} certificate;
struct {
Bytes *types;
int nca;
Bytes **cas;
} certificateRequest;
struct {
Bytes *key;
} clientKeyExchange;
Finished finished;
} u;
} Msg;
typedef struct TlsSec{
char *server; // name of remote; nil for server
int ok; // <0 killed; ==0 in progress; >0 reusable
RSApub *rsapub;
AuthRpc *rpc; // factotum for rsa private key
uchar sec[MasterSecretSize]; // master secret
uchar crandom[RandomSize]; // client random
uchar srandom[RandomSize]; // server random
int clientVers; // version in ClientHello
int vers; // final version
// byte generation and handshake checksum
void (*prf)(uchar*, int, uchar*, int, char*, uchar*, int, uchar*, int);
void (*setFinished)(TlsSec*, MD5state, SHAstate, uchar*, int);
int nfin;
} TlsSec;
enum {
TLSVersion = 0x0301,
SSL3Version = 0x0300,
ProtocolVersion = 0x0301, // maximum version we speak
MinProtoVersion = 0x0300, // limits on version we accept
MaxProtoVersion = 0x03ff,
};
// handshake type
enum {
HHelloRequest,
HClientHello,
HServerHello,
HSSL2ClientHello = 9, /* local convention; see devtls.c */
HCertificate = 11,
HServerKeyExchange,
HCertificateRequest,
HServerHelloDone,
HCertificateVerify,
HClientKeyExchange,
HFinished = 20,
HMax
};
// alerts
enum {
ECloseNotify = 0,
EUnexpectedMessage = 10,
EBadRecordMac = 20,
EDecryptionFailed = 21,
ERecordOverflow = 22,
EDecompressionFailure = 30,
EHandshakeFailure = 40,
ENoCertificate = 41,
EBadCertificate = 42,
EUnsupportedCertificate = 43,
ECertificateRevoked = 44,
ECertificateExpired = 45,
ECertificateUnknown = 46,
EIllegalParameter = 47,
EUnknownCa = 48,
EAccessDenied = 49,
EDecodeError = 50,
EDecryptError = 51,
EExportRestriction = 60,
EProtocolVersion = 70,
EInsufficientSecurity = 71,
EInternalError = 80,
EUserCanceled = 90,
ENoRenegotiation = 100,
EMax = 256
};
// cipher suites
enum {
TLS_NULL_WITH_NULL_NULL = 0x0000,
TLS_RSA_WITH_NULL_MD5 = 0x0001,
TLS_RSA_WITH_NULL_SHA = 0x0002,
TLS_RSA_EXPORT_WITH_RC4_40_MD5 = 0x0003,
TLS_RSA_WITH_RC4_128_MD5 = 0x0004,
TLS_RSA_WITH_RC4_128_SHA = 0x0005,
TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5 = 0X0006,
TLS_RSA_WITH_IDEA_CBC_SHA = 0X0007,
TLS_RSA_EXPORT_WITH_DES40_CBC_SHA = 0X0008,
TLS_RSA_WITH_DES_CBC_SHA = 0X0009,
TLS_RSA_WITH_3DES_EDE_CBC_SHA = 0X000A,
TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA = 0X000B,
TLS_DH_DSS_WITH_DES_CBC_SHA = 0X000C,
TLS_DH_DSS_WITH_3DES_EDE_CBC_SHA = 0X000D,
TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA = 0X000E,
TLS_DH_RSA_WITH_DES_CBC_SHA = 0X000F,
TLS_DH_RSA_WITH_3DES_EDE_CBC_SHA = 0X0010,
TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA = 0X0011,
TLS_DHE_DSS_WITH_DES_CBC_SHA = 0X0012,
TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA = 0X0013, // ZZZ must be implemented for tls1.0 compliance
TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA = 0X0014,
TLS_DHE_RSA_WITH_DES_CBC_SHA = 0X0015,
TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA = 0X0016,
TLS_DH_anon_EXPORT_WITH_RC4_40_MD5 = 0x0017,
TLS_DH_anon_WITH_RC4_128_MD5 = 0x0018,
TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA = 0X0019,
TLS_DH_anon_WITH_DES_CBC_SHA = 0X001A,
TLS_DH_anon_WITH_3DES_EDE_CBC_SHA = 0X001B,
TLS_RSA_WITH_AES_128_CBC_SHA = 0X002f, // aes, aka rijndael with 128 bit blocks
TLS_DH_DSS_WITH_AES_128_CBC_SHA = 0X0030,
TLS_DH_RSA_WITH_AES_128_CBC_SHA = 0X0031,
TLS_DHE_DSS_WITH_AES_128_CBC_SHA = 0X0032,
TLS_DHE_RSA_WITH_AES_128_CBC_SHA = 0X0033,
TLS_DH_anon_WITH_AES_128_CBC_SHA = 0X0034,
TLS_RSA_WITH_AES_256_CBC_SHA = 0X0035,
TLS_DH_DSS_WITH_AES_256_CBC_SHA = 0X0036,
TLS_DH_RSA_WITH_AES_256_CBC_SHA = 0X0037,
TLS_DHE_DSS_WITH_AES_256_CBC_SHA = 0X0038,
TLS_DHE_RSA_WITH_AES_256_CBC_SHA = 0X0039,
TLS_DH_anon_WITH_AES_256_CBC_SHA = 0X003A,
CipherMax
};
// compression methods
enum {
CompressionNull = 0,
CompressionMax
};
static Algs cipherAlgs[] = {
{"rc4_128", "md5", 2 * (16 + MD5dlen), TLS_RSA_WITH_RC4_128_MD5},
{"rc4_128", "sha1", 2 * (16 + SHA1dlen), TLS_RSA_WITH_RC4_128_SHA},
{"3des_ede_cbc","sha1",2*(4*8+SHA1dlen), TLS_RSA_WITH_3DES_EDE_CBC_SHA},
};
static uchar compressors[] = {
CompressionNull,
};
static TlsConnection *tlsServer2(int ctl, int hand, uchar *cert, int ncert, int (*trace)(char*fmt, ...));
static TlsConnection *tlsClient2(int ctl, int hand, uchar *csid, int ncsid, int (*trace)(char*fmt, ...));
static void msgClear(Msg *m);
static char* msgPrint(char *buf, int n, Msg *m);
static int msgRecv(TlsConnection *c, Msg *m);
static int msgSend(TlsConnection *c, Msg *m, int act);
static void tlsError(TlsConnection *c, int err, char *msg, ...);
#pragma varargck argpos tlsError 3
static int setVersion(TlsConnection *c, int version);
static int finishedMatch(TlsConnection *c, Finished *f);
static void tlsConnectionFree(TlsConnection *c);
static int setAlgs(TlsConnection *c, int a);
static int okCipher(Ints *cv);
static int okCompression(Bytes *cv);
static int initCiphers(void);
static Ints* makeciphers(void);
static TlsSec* tlsSecInits(int cvers, uchar *csid, int ncsid, uchar *crandom, uchar *ssid, int *nssid, uchar *srandom);
static int tlsSecSecrets(TlsSec *sec, int vers, uchar *epm, int nepm, uchar *kd, int nkd);
static TlsSec* tlsSecInitc(int cvers, uchar *crandom);
static int tlsSecSecretc(TlsSec *sec, uchar *sid, int nsid, uchar *srandom, uchar *cert, int ncert, int vers, uchar **epm, int *nepm, uchar *kd, int nkd);
static int tlsSecFinished(TlsSec *sec, MD5state md5, SHAstate sha1, uchar *fin, int nfin, int isclient);
static void tlsSecOk(TlsSec *sec);
static void tlsSecKill(TlsSec *sec);
static void tlsSecClose(TlsSec *sec);
static void setMasterSecret(TlsSec *sec, Bytes *pm);
static void serverMasterSecret(TlsSec *sec, uchar *epm, int nepm);
static void setSecrets(TlsSec *sec, uchar *kd, int nkd);
static int clientMasterSecret(TlsSec *sec, RSApub *pub, uchar **epm, int *nepm);
static Bytes *pkcs1_encrypt(Bytes* data, RSApub* key, int blocktype);
static Bytes *pkcs1_decrypt(TlsSec *sec, uchar *epm, int nepm);
static void tlsSetFinished(TlsSec *sec, MD5state hsmd5, SHAstate hssha1, uchar *finished, int isClient);
static void sslSetFinished(TlsSec *sec, MD5state hsmd5, SHAstate hssha1, uchar *finished, int isClient);
static void sslPRF(uchar *buf, int nbuf, uchar *key, int nkey, char *label,
uchar *seed0, int nseed0, uchar *seed1, int nseed1);
static int setVers(TlsSec *sec, int version);
static AuthRpc* factotum_rsa_open(uchar *cert, int certlen);
static mpint* factotum_rsa_decrypt(AuthRpc *rpc, mpint *cipher);
static void factotum_rsa_close(AuthRpc*rpc);
static void* emalloc(int);
static void* erealloc(void*, int);
static void put32(uchar *p, u32int);
static void put24(uchar *p, int);
static void put16(uchar *p, int);
static u32int get32(uchar *p);
static int get24(uchar *p);
static int get16(uchar *p);
static Bytes* newbytes(int len);
static Bytes* makebytes(uchar* buf, int len);
static void freebytes(Bytes* b);
static Ints* newints(int len);
static Ints* makeints(int* buf, int len);
static void freeints(Ints* b);
//================= client/server ========================
// push TLS onto fd, returning new (application) file descriptor
// or -1 if error.
int
tlsServer(int fd, TLSconn *conn)
{
char buf[8];
char dname[64];
int n, data, ctl, hand;
TlsConnection *tls;
if(conn == nil)
return -1;
ctl = open("#a/tls/clone", ORDWR);
if(ctl < 0)
return -1;
n = read(ctl, buf, sizeof(buf)-1);
if(n < 0){
close(ctl);
return -1;
}
buf[n] = 0;
sprint(conn->dir, "#a/tls/%s", buf);
sprint(dname, "#a/tls/%s/hand", buf);
hand = open(dname, ORDWR);
if(hand < 0){
close(ctl);
return -1;
}
fprint(ctl, "fd %d 0x%x", fd, ProtocolVersion);
tls = tlsServer2(ctl, hand, conn->cert, conn->certlen, conn->trace);
sprint(dname, "#a/tls/%s/data", buf);
data = open(dname, ORDWR);
close(fd);
close(hand);
close(ctl);
if(data < 0){
return -1;
}
if(tls == nil){
close(data);
return -1;
}
if(conn->cert)
free(conn->cert);
conn->cert = 0; // client certificates are not yet implemented
conn->certlen = 0;
conn->sessionIDlen = tls->sid->len;
conn->sessionID = emalloc(conn->sessionIDlen);
memcpy(conn->sessionID, tls->sid->data, conn->sessionIDlen);
tlsConnectionFree(tls);
return data;
}
// push TLS onto fd, returning new (application) file descriptor
// or -1 if error.
int
tlsClient(int fd, TLSconn *conn)
{
char buf[8];
char dname[64];
int n, data, ctl, hand;
TlsConnection *tls;
if(!conn)
return -1;
ctl = open("#a/tls/clone", ORDWR);
if(ctl < 0)
return -1;
n = read(ctl, buf, sizeof(buf)-1);
if(n < 0){
close(ctl);
return -1;
}
buf[n] = 0;
sprint(conn->dir, "#a/tls/%s", buf);
sprint(dname, "#a/tls/%s/hand", buf);
hand = open(dname, ORDWR);
if(hand < 0){
close(ctl);
return -1;
}
sprint(dname, "#a/tls/%s/data", buf);
data = open(dname, ORDWR);
if(data < 0)
return -1;
fprint(ctl, "fd %d 0x%x", fd, ProtocolVersion);
tls = tlsClient2(ctl, hand, conn->sessionID, conn->sessionIDlen, conn->trace);
close(fd);
close(hand);
close(ctl);
if(tls == nil){
close(data);
return -1;
}
conn->certlen = tls->cert->len;
conn->cert = emalloc(conn->certlen);
memcpy(conn->cert, tls->cert->data, conn->certlen);
conn->sessionIDlen = tls->sid->len;
conn->sessionID = emalloc(conn->sessionIDlen);
memcpy(conn->sessionID, tls->sid->data, conn->sessionIDlen);
tlsConnectionFree(tls);
return data;
}
static TlsConnection *
tlsServer2(int ctl, int hand, uchar *cert, int ncert, int (*trace)(char*fmt, ...))
{
TlsConnection *c;
Msg m;
Bytes *csid;
uchar sid[SidSize], kd[MaxKeyData];
char *secrets;
int cipher, compressor, nsid, rv;
if(trace)
trace("tlsServer2\n");
if(!initCiphers())
return nil;
c = emalloc(sizeof(TlsConnection));
c->ctl = ctl;
c->hand = hand;
c->trace = trace;
c->version = ProtocolVersion;
memset(&m, 0, sizeof(m));
if(!msgRecv(c, &m)){
if(trace)
trace("initial msgRecv failed\n");
goto Err;
}
if(m.tag != HClientHello) {
tlsError(c, EUnexpectedMessage, "expected a client hello");
goto Err;
}
c->clientVersion = m.u.clientHello.version;
if(trace)
trace("ClientHello version %x\n", c->clientVersion);
if(setVersion(c, m.u.clientHello.version) < 0) {
tlsError(c, EIllegalParameter, "incompatible version");
goto Err;
}
memmove(c->crandom, m.u.clientHello.random, RandomSize);
cipher = okCipher(m.u.clientHello.ciphers);
if(cipher < 0) {
// reply with EInsufficientSecurity if we know that's the case
if(cipher == -2)
tlsError(c, EInsufficientSecurity, "cipher suites too weak");
else
tlsError(c, EHandshakeFailure, "no matching cipher suite");
goto Err;
}
if(!setAlgs(c, cipher)){
tlsError(c, EHandshakeFailure, "no matching cipher suite");
goto Err;
}
compressor = okCompression(m.u.clientHello.compressors);
if(compressor < 0) {
tlsError(c, EHandshakeFailure, "no matching compressor");
goto Err;
}
csid = m.u.clientHello.sid;
if(trace)
trace(" cipher %d, compressor %d, csidlen %d\n", cipher, compressor, csid->len);
c->sec = tlsSecInits(c->clientVersion, csid->data, csid->len, c->crandom, sid, &nsid, c->srandom);
if(c->sec == nil){
tlsError(c, EHandshakeFailure, "can't initialize security: %r");
goto Err;
}
c->sec->rpc = factotum_rsa_open(cert, ncert);
if(c->sec->rpc == nil){
tlsError(c, EHandshakeFailure, "factotum_rsa_open: %r");
goto Err;
}
c->sec->rsapub = X509toRSApub(cert, ncert, nil, 0);
msgClear(&m);
m.tag = HServerHello;
m.u.serverHello.version = c->version;
memmove(m.u.serverHello.random, c->srandom, RandomSize);
m.u.serverHello.cipher = cipher;
m.u.serverHello.compressor = compressor;
c->sid = makebytes(sid, nsid);
m.u.serverHello.sid = makebytes(c->sid->data, c->sid->len);
if(!msgSend(c, &m, AQueue))
goto Err;
msgClear(&m);
m.tag = HCertificate;
m.u.certificate.ncert = 1;
m.u.certificate.certs = emalloc(m.u.certificate.ncert * sizeof(Bytes));
m.u.certificate.certs[0] = makebytes(cert, ncert);
if(!msgSend(c, &m, AQueue))
goto Err;
msgClear(&m);
m.tag = HServerHelloDone;
if(!msgSend(c, &m, AFlush))
goto Err;
msgClear(&m);
if(!msgRecv(c, &m))
goto Err;
if(m.tag != HClientKeyExchange) {
tlsError(c, EUnexpectedMessage, "expected a client key exchange");
goto Err;
}
if(tlsSecSecrets(c->sec, c->version, m.u.clientKeyExchange.key->data, m.u.clientKeyExchange.key->len, kd, c->nsecret) < 0){
tlsError(c, EHandshakeFailure, "couldn't set secrets: %r");
goto Err;
}
if(trace)
trace("tls secrets\n");
secrets = (char*)emalloc(2*c->nsecret);
enc64(secrets, 2*c->nsecret, kd, c->nsecret);
rv = fprint(c->ctl, "secret %s %s 0 %s", c->digest, c->enc, secrets);
memset(secrets, 0, 2*c->nsecret);
free(secrets);
memset(kd, 0, c->nsecret);
if(rv < 0){
tlsError(c, EHandshakeFailure, "can't set keys: %r");
goto Err;
}
msgClear(&m);
/* no CertificateVerify; skip to Finished */
if(tlsSecFinished(c->sec, c->hsmd5, c->hssha1, c->finished.verify, c->finished.n, 1) < 0){
tlsError(c, EInternalError, "can't set finished: %r");
goto Err;
}
if(!msgRecv(c, &m))
goto Err;
if(m.tag != HFinished) {
tlsError(c, EUnexpectedMessage, "expected a finished");
goto Err;
}
if(!finishedMatch(c, &m.u.finished)) {
tlsError(c, EHandshakeFailure, "finished verification failed");
goto Err;
}
msgClear(&m);
/* change cipher spec */
if(fprint(c->ctl, "changecipher") < 0){
tlsError(c, EInternalError, "can't enable cipher: %r");
goto Err;
}
if(tlsSecFinished(c->sec, c->hsmd5, c->hssha1, c->finished.verify, c->finished.n, 0) < 0){
tlsError(c, EInternalError, "can't set finished: %r");
goto Err;
}
m.tag = HFinished;
m.u.finished = c->finished;
if(!msgSend(c, &m, AFlush))
goto Err;
msgClear(&m);
if(trace)
trace("tls finished\n");
if(fprint(c->ctl, "opened") < 0)
goto Err;
tlsSecOk(c->sec);
return c;
Err:
msgClear(&m);
tlsConnectionFree(c);
return 0;
}
static TlsConnection *
tlsClient2(int ctl, int hand, uchar *csid, int ncsid, int (*trace)(char*fmt, ...))
{
TlsConnection *c;
Msg m;
uchar kd[MaxKeyData], *epm;
char *secrets;
int creq, nepm, rv;
if(!initCiphers())
return nil;
epm = nil;
c = emalloc(sizeof(TlsConnection));
c->version = ProtocolVersion;
c->ctl = ctl;
c->hand = hand;
c->trace = trace;
c->isClient = 1;
c->clientVersion = c->version;
c->sec = tlsSecInitc(c->clientVersion, c->crandom);
if(c->sec == nil)
goto Err;
/* client hello */
memset(&m, 0, sizeof(m));
m.tag = HClientHello;
m.u.clientHello.version = c->clientVersion;
memmove(m.u.clientHello.random, c->crandom, RandomSize);
m.u.clientHello.sid = makebytes(csid, ncsid);
m.u.clientHello.ciphers = makeciphers();
m.u.clientHello.compressors = makebytes(compressors,sizeof(compressors));
if(!msgSend(c, &m, AFlush))
goto Err;
msgClear(&m);
/* server hello */
if(!msgRecv(c, &m))
goto Err;
if(m.tag != HServerHello) {
tlsError(c, EUnexpectedMessage, "expected a server hello");
goto Err;
}
if(setVersion(c, m.u.serverHello.version) < 0) {
tlsError(c, EIllegalParameter, "incompatible version %r");
goto Err;
}
memmove(c->srandom, m.u.serverHello.random, RandomSize);
c->sid = makebytes(m.u.serverHello.sid->data, m.u.serverHello.sid->len);
if(c->sid->len != 0 && c->sid->len != SidSize) {
tlsError(c, EIllegalParameter, "invalid server session identifier");
goto Err;
}
if(!setAlgs(c, m.u.serverHello.cipher)) {
tlsError(c, EIllegalParameter, "invalid cipher suite");
goto Err;
}
if(m.u.serverHello.compressor != CompressionNull) {
tlsError(c, EIllegalParameter, "invalid compression");
goto Err;
}
msgClear(&m);
/* certificate */
if(!msgRecv(c, &m) || m.tag != HCertificate) {
tlsError(c, EUnexpectedMessage, "expected a certificate");
goto Err;
}
if(m.u.certificate.ncert < 1) {
tlsError(c, EIllegalParameter, "runt certificate");
goto Err;
}
c->cert = makebytes(m.u.certificate.certs[0]->data, m.u.certificate.certs[0]->len);
msgClear(&m);
/* server key exchange (optional) */
if(!msgRecv(c, &m))
goto Err;
if(m.tag == HServerKeyExchange) {
tlsError(c, EUnexpectedMessage, "got an server key exchange");
goto Err;
// If implementing this later, watch out for rollback attack
// described in Wagner Schneier 1996, section 4.4.
}
/* certificate request (optional) */
creq = 0;
if(m.tag == HCertificateRequest) {
creq = 1;
msgClear(&m);
if(!msgRecv(c, &m))
goto Err;
}
if(m.tag != HServerHelloDone) {
tlsError(c, EUnexpectedMessage, "expected a server hello done");
goto Err;
}
msgClear(&m);
if(tlsSecSecretc(c->sec, c->sid->data, c->sid->len, c->srandom,
c->cert->data, c->cert->len, c->version, &epm, &nepm,
kd, c->nsecret) < 0){
tlsError(c, EBadCertificate, "invalid x509/rsa certificate");
goto Err;
}
secrets = (char*)emalloc(2*c->nsecret);
enc64(secrets, 2*c->nsecret, kd, c->nsecret);
rv = fprint(c->ctl, "secret %s %s 1 %s", c->digest, c->enc, secrets);
memset(secrets, 0, 2*c->nsecret);
free(secrets);
memset(kd, 0, c->nsecret);
if(rv < 0){
tlsError(c, EHandshakeFailure, "can't set keys: %r");
goto Err;
}
if(creq) {
/* send a zero length certificate */
m.tag = HCertificate;
if(!msgSend(c, &m, AFlush))
goto Err;
msgClear(&m);
}
/* client key exchange */
m.tag = HClientKeyExchange;
m.u.clientKeyExchange.key = makebytes(epm, nepm);
free(epm);
epm = nil;
if(m.u.clientKeyExchange.key == nil) {
tlsError(c, EHandshakeFailure, "can't set secret: %r");
goto Err;
}
if(!msgSend(c, &m, AFlush))
goto Err;
msgClear(&m);
/* change cipher spec */
if(fprint(c->ctl, "changecipher") < 0){
tlsError(c, EInternalError, "can't enable cipher: %r");
goto Err;
}
// Cipherchange must occur immediately before Finished to avoid
// potential hole; see section 4.3 of Wagner Schneier 1996.
if(tlsSecFinished(c->sec, c->hsmd5, c->hssha1, c->finished.verify, c->finished.n, 1) < 0){
tlsError(c, EInternalError, "can't set finished 1: %r");
goto Err;
}
m.tag = HFinished;
m.u.finished = c->finished;
if(!msgSend(c, &m, AFlush)) {
fprint(2, "tlsClient nepm=%d\n", nepm);
tlsError(c, EInternalError, "can't flush after client Finished: %r");
goto Err;
}
msgClear(&m);
if(tlsSecFinished(c->sec, c->hsmd5, c->hssha1, c->finished.verify, c->finished.n, 0) < 0){
fprint(2, "tlsClient nepm=%d\n", nepm);
tlsError(c, EInternalError, "can't set finished 0: %r");
goto Err;
}
if(!msgRecv(c, &m)) {
fprint(2, "tlsClient nepm=%d\n", nepm);
tlsError(c, EInternalError, "can't read server Finished: %r");
goto Err;
}
if(m.tag != HFinished) {
fprint(2, "tlsClient nepm=%d\n", nepm);
tlsError(c, EUnexpectedMessage, "expected a Finished msg from server");
goto Err;
}
if(!finishedMatch(c, &m.u.finished)) {
tlsError(c, EHandshakeFailure, "finished verification failed");
goto Err;
}
msgClear(&m);
if(fprint(c->ctl, "opened") < 0){
if(trace)
trace("unable to do final open: %r\n");
goto Err;
}
tlsSecOk(c->sec);
return c;
Err:
free(epm);
msgClear(&m);
tlsConnectionFree(c);
return 0;
}
//================= message functions ========================
static uchar sendbuf[9000], *sendp;
static int
msgSend(TlsConnection *c, Msg *m, int act)
{
uchar *p; // sendp = start of new message; p = write pointer
int nn, n, i;
if(sendp == nil)
sendp = sendbuf;
p = sendp;
if(c->trace)
c->trace("send %s", msgPrint((char*)p, (sizeof sendbuf) - (p-sendbuf), m));
p[0] = m->tag; // header - fill in size later
p += 4;
switch(m->tag) {
default:
tlsError(c, EInternalError, "can't encode a %d", m->tag);
goto Err;
case HClientHello:
// version
put16(p, m->u.clientHello.version);
p += 2;
// random
memmove(p, m->u.clientHello.random, RandomSize);
p += RandomSize;
// sid
n = m->u.clientHello.sid->len;
assert(n < 256);
p[0] = n;
memmove(p+1, m->u.clientHello.sid->data, n);
p += n+1;
n = m->u.clientHello.ciphers->len;
assert(n > 0 && n < 200);
put16(p, n*2);
p += 2;
for(i=0; i<n; i++) {
put16(p, m->u.clientHello.ciphers->data[i]);
p += 2;
}
n = m->u.clientHello.compressors->len;
assert(n > 0);
p[0] = n;
memmove(p+1, m->u.clientHello.compressors->data, n);
p += n+1;
break;
case HServerHello:
put16(p, m->u.serverHello.version);
p += 2;
// random
memmove(p, m->u.serverHello.random, RandomSize);
p += RandomSize;
// sid
n = m->u.serverHello.sid->len;
assert(n < 256);
p[0] = n;
memmove(p+1, m->u.serverHello.sid->data, n);
p += n+1;
put16(p, m->u.serverHello.cipher);
p += 2;
p[0] = m->u.serverHello.compressor;
p += 1;
break;
case HServerHelloDone:
break;
case HCertificate:
nn = 0;
for(i = 0; i < m->u.certificate.ncert; i++)
nn += 3 + m->u.certificate.certs[i]->len;
if(p + 3 + nn - sendbuf > sizeof(sendbuf)) {
tlsError(c, EInternalError, "output buffer too small for certificate");
goto Err;
}
put24(p, nn);
p += 3;
for(i = 0; i < m->u.certificate.ncert; i++){
put24(p, m->u.certificate.certs[i]->len);
p += 3;
memmove(p, m->u.certificate.certs[i]->data, m->u.certificate.certs[i]->len);
p += m->u.certificate.certs[i]->len;
}
break;
case HClientKeyExchange:
n = m->u.clientKeyExchange.key->len;
if(c->version != SSL3Version){
put16(p, n);
p += 2;
}
memmove(p, m->u.clientKeyExchange.key->data, n);
p += n;
break;
case HFinished:
memmove(p, m->u.finished.verify, m->u.finished.n);
p += m->u.finished.n;
break;
}
// go back and fill in size
n = p-sendp;
assert(p <= sendbuf+sizeof(sendbuf));
put24(sendp+1, n-4);
// remember hash of Handshake messages
if(m->tag != HHelloRequest) {
md5(sendp, n, 0, &c->hsmd5);
sha1(sendp, n, 0, &c->hssha1);
}
sendp = p;
if(act == AFlush){
sendp = sendbuf;
if(write(c->hand, sendbuf, p-sendbuf) < 0){
fprint(2, "write error: %r\n");
goto Err;
}
}
msgClear(m);
return 1;
Err:
msgClear(m);
return 0;
}
static uchar*
tlsReadN(TlsConnection *c, int n)
{
uchar *p;
int nn, nr;
nn = c->ep - c->rp;
if(nn < n){
if(c->rp != c->buf){
memmove(c->buf, c->rp, nn);
c->rp = c->buf;
c->ep = &c->buf[nn];
}
for(; nn < n; nn += nr) {
nr = read(c->hand, &c->rp[nn], n - nn);
if(nr <= 0)
return nil;
c->ep += nr;
}
}
p = c->rp;
c->rp += n;
return p;
}
static int
msgRecv(TlsConnection *c, Msg *m)
{
uchar *p;
int type, n, nn, i, nsid, nrandom, nciph;
for(;;) {
p = tlsReadN(c, 4);
if(p == nil)
return 0;
type = p[0];
n = get24(p+1);
if(type != HHelloRequest)
break;
if(n != 0) {
tlsError(c, EDecodeError, "invalid hello request during handshake");
return 0;
}
}
if(n > sizeof(c->buf)) {
tlsError(c, EDecodeError, "handshake message too long %d %d", n, sizeof(c->buf));
return 0;
}
if(type == HSSL2ClientHello){
/* Cope with an SSL3 ClientHello expressed in SSL2 record format.
This is sent by some clients that we must interoperate
with, such as Java's JSSE and Microsoft's Internet Explorer. */
p = tlsReadN(c, n);
if(p == nil)
return 0;
md5(p, n, 0, &c->hsmd5);
sha1(p, n, 0, &c->hssha1);
m->tag = HClientHello;
if(n < 22)
goto Short;
m->u.clientHello.version = get16(p+1);
p += 3;
n -= 3;
nn = get16(p); /* cipher_spec_len */
nsid = get16(p + 2);
nrandom = get16(p + 4);
p += 6;
n -= 6;
if(nsid != 0 /* no sid's, since shouldn't restart using ssl2 header */
|| nrandom < 16 || nn % 3)
goto Err;
if(c->trace && (n - nrandom != nn))
c->trace("n-nrandom!=nn: n=%d nrandom=%d nn=%d\n", n, nrandom, nn);
/* ignore ssl2 ciphers and look for {0x00, ssl3 cipher} */
nciph = 0;
for(i = 0; i < nn; i += 3)
if(p[i] == 0)
nciph++;
m->u.clientHello.ciphers = newints(nciph);
nciph = 0;
for(i = 0; i < nn; i += 3)
if(p[i] == 0)
m->u.clientHello.ciphers->data[nciph++] = get16(&p[i + 1]);
p += nn;
m->u.clientHello.sid = makebytes(nil, 0);
if(nrandom > RandomSize)
nrandom = RandomSize;
memset(m->u.clientHello.random, 0, RandomSize - nrandom);
memmove(&m->u.clientHello.random[RandomSize - nrandom], p, nrandom);
m->u.clientHello.compressors = newbytes(1);
m->u.clientHello.compressors->data[0] = CompressionNull;
goto Ok;
}
md5(p, 4, 0, &c->hsmd5);
sha1(p, 4, 0, &c->hssha1);
p = tlsReadN(c, n);
if(p == nil)
return 0;
md5(p, n, 0, &c->hsmd5);
sha1(p, n, 0, &c->hssha1);
m->tag = type;
switch(type) {
default:
tlsError(c, EUnexpectedMessage, "can't decode a %d", type);
goto Err;
case HClientHello:
if(n < 2)
goto Short;
m->u.clientHello.version = get16(p);
p += 2;
n -= 2;
if(n < RandomSize)
goto Short;
memmove(m->u.clientHello.random, p, RandomSize);
p += RandomSize;
n -= RandomSize;
if(n < 1 || n < p[0]+1)
goto Short;
m->u.clientHello.sid = makebytes(p+1, p[0]);
p += m->u.clientHello.sid->len+1;
n -= m->u.clientHello.sid->len+1;
if(n < 2)
goto Short;
nn = get16(p);
p += 2;
n -= 2;
if((nn & 1) || n < nn || nn < 2)
goto Short;
m->u.clientHello.ciphers = newints(nn >> 1);
for(i = 0; i < nn; i += 2)
m->u.clientHello.ciphers->data[i >> 1] = get16(&p[i]);
p += nn;
n -= nn;
if(n < 1 || n < p[0]+1 || p[0] == 0)
goto Short;
nn = p[0];
m->u.clientHello.compressors = newbytes(nn);
memmove(m->u.clientHello.compressors->data, p+1, nn);
n -= nn + 1;
break;
case HServerHello:
if(n < 2)
goto Short;
m->u.serverHello.version = get16(p);
p += 2;
n -= 2;
if(n < RandomSize)
goto Short;
memmove(m->u.serverHello.random, p, RandomSize);
p += RandomSize;
n -= RandomSize;
if(n < 1 || n < p[0]+1)
goto Short;
m->u.serverHello.sid = makebytes(p+1, p[0]);
p += m->u.serverHello.sid->len+1;
n -= m->u.serverHello.sid->len+1;
if(n < 3)
goto Short;
m->u.serverHello.cipher = get16(p);
m->u.serverHello.compressor = p[2];
n -= 3;
break;
case HCertificate:
if(n < 3)
goto Short;
nn = get24(p);
p += 3;
n -= 3;
if(n != nn)
goto Short;
/* certs */
i = 0;
while(n > 0) {
if(n < 3)
goto Short;
nn = get24(p);
p += 3;
n -= 3;
if(nn > n)
goto Short;
m->u.certificate.ncert = i+1;
m->u.certificate.certs = erealloc(m->u.certificate.certs, (i+1)*sizeof(Bytes));
m->u.certificate.certs[i] = makebytes(p, nn);
p += nn;
n -= nn;
i++;
}
break;
case HCertificateRequest:
if(n < 2)
goto Short;
nn = get16(p);
p += 2;
n -= 2;
if(nn < 1 || nn > n)
goto Short;
m->u.certificateRequest.types = makebytes(p, nn);
nn = get24(p);
p += 3;
n -= 3;
if(nn == 0 || n != nn)
goto Short;
/* cas */
i = 0;
while(n > 0) {
if(n < 2)
goto Short;
nn = get16(p);
p += 2;
n -= 2;
if(nn < 1 || nn > n)
goto Short;
m->u.certificateRequest.nca = i+1;
m->u.certificateRequest.cas = erealloc(m->u.certificateRequest.cas, (i+1)*sizeof(Bytes));
m->u.certificateRequest.cas[i] = makebytes(p, nn);
p += nn;
n -= nn;
i++;
}
break;
case HServerHelloDone:
break;
case HClientKeyExchange:
/*
* this message depends upon the encryption selected
* assume rsa.
*/
if(c->version == SSL3Version)
nn = n;
else{
if(n < 2)
goto Short;
nn = get16(p);
p += 2;
n -= 2;
}
if(n < nn)
goto Short;
m->u.clientKeyExchange.key = makebytes(p, nn);
n -= nn;
break;
case HFinished:
m->u.finished.n = c->finished.n;
if(n < m->u.finished.n)
goto Short;
memmove(m->u.finished.verify, p, m->u.finished.n);
n -= m->u.finished.n;
break;
}
if(type != HClientHello && n != 0)
goto Short;
Ok:
if(c->trace){
char buf[8000];
c->trace("recv %s", msgPrint(buf, sizeof buf, m));
}
return 1;
Short:
tlsError(c, EDecodeError, "handshake message has invalid length");
Err:
msgClear(m);
return 0;
}
static void
msgClear(Msg *m)
{
int i;
switch(m->tag) {
default:
sysfatal("msgClear: unknown message type: %d\n", m->tag);
case HHelloRequest:
break;
case HClientHello:
freebytes(m->u.clientHello.sid);
freeints(m->u.clientHello.ciphers);
freebytes(m->u.clientHello.compressors);
break;
case HServerHello:
freebytes(m->u.clientHello.sid);
break;
case HCertificate:
for(i=0; i<m->u.certificate.ncert; i++)
freebytes(m->u.certificate.certs[i]);
free(m->u.certificate.certs);
break;
case HCertificateRequest:
freebytes(m->u.certificateRequest.types);
for(i=0; i<m->u.certificateRequest.nca; i++)
freebytes(m->u.certificateRequest.cas[i]);
free(m->u.certificateRequest.cas);
break;
case HServerHelloDone:
break;
case HClientKeyExchange:
freebytes(m->u.clientKeyExchange.key);
break;
case HFinished:
break;
}
memset(m, 0, sizeof(Msg));
}
static char *
bytesPrint(char *bs, char *be, char *s0, Bytes *b, char *s1)
{
int i;
if(s0)
bs = seprint(bs, be, "%s", s0);
bs = seprint(bs, be, "[");
if(b == nil)
bs = seprint(bs, be, "nil");
else
for(i=0; i<b->len; i++)
bs = seprint(bs, be, "%.2x ", b->data[i]);
bs = seprint(bs, be, "]");
if(s1)
bs = seprint(bs, be, "%s", s1);
return bs;
}
static char *
intsPrint(char *bs, char *be, char *s0, Ints *b, char *s1)
{
int i;
if(s0)
bs = seprint(bs, be, "%s", s0);
bs = seprint(bs, be, "[");
if(b == nil)
bs = seprint(bs, be, "nil");
else
for(i=0; i<b->len; i++)
bs = seprint(bs, be, "%x ", b->data[i]);
bs = seprint(bs, be, "]");
if(s1)
bs = seprint(bs, be, "%s", s1);
return bs;
}
static char*
msgPrint(char *buf, int n, Msg *m)
{
int i;
char *bs = buf, *be = buf+n;
switch(m->tag) {
default:
bs = seprint(bs, be, "unknown %d\n", m->tag);
break;
case HClientHello:
bs = seprint(bs, be, "ClientHello\n");
bs = seprint(bs, be, "\tversion: %.4x\n", m->u.clientHello.version);
bs = seprint(bs, be, "\trandom: ");
for(i=0; i<RandomSize; i++)
bs = seprint(bs, be, "%.2x", m->u.clientHello.random[i]);
bs = seprint(bs, be, "\n");
bs = bytesPrint(bs, be, "\tsid: ", m->u.clientHello.sid, "\n");
bs = intsPrint(bs, be, "\tciphers: ", m->u.clientHello.ciphers, "\n");
bs = bytesPrint(bs, be, "\tcompressors: ", m->u.clientHello.compressors, "\n");
break;
case HServerHello:
bs = seprint(bs, be, "ServerHello\n");
bs = seprint(bs, be, "\tversion: %.4x\n", m->u.serverHello.version);
bs = seprint(bs, be, "\trandom: ");
for(i=0; i<RandomSize; i++)
bs = seprint(bs, be, "%.2x", m->u.serverHello.random[i]);
bs = seprint(bs, be, "\n");
bs = bytesPrint(bs, be, "\tsid: ", m->u.serverHello.sid, "\n");
bs = seprint(bs, be, "\tcipher: %.4x\n", m->u.serverHello.cipher);
bs = seprint(bs, be, "\tcompressor: %.2x\n", m->u.serverHello.compressor);
break;
case HCertificate:
bs = seprint(bs, be, "Certificate\n");
for(i=0; i<m->u.certificate.ncert; i++)
bs = bytesPrint(bs, be, "\t", m->u.certificate.certs[i], "\n");
break;
case HCertificateRequest:
bs = seprint(bs, be, "CertificateRequest\n");
bs = bytesPrint(bs, be, "\ttypes: ", m->u.certificateRequest.types, "\n");
bs = seprint(bs, be, "\tcertificateauthorities\n");
for(i=0; i<m->u.certificateRequest.nca; i++)
bs = bytesPrint(bs, be, "\t\t", m->u.certificateRequest.cas[i], "\n");
break;
case HServerHelloDone:
bs = seprint(bs, be, "ServerHelloDone\n");
break;
case HClientKeyExchange:
bs = seprint(bs, be, "HClientKeyExchange\n");
bs = bytesPrint(bs, be, "\tkey: ", m->u.clientKeyExchange.key, "\n");
break;
case HFinished:
bs = seprint(bs, be, "HFinished\n");
for(i=0; i<m->u.finished.n; i++)
bs = seprint(bs, be, "%.2x", m->u.finished.verify[i]);
bs = seprint(bs, be, "\n");
break;
}
USED(bs);
return buf;
}
static void
tlsError(TlsConnection *c, int err, char *fmt, ...)
{
char msg[512];
va_list arg;
va_start(arg, fmt);
vseprint(msg, msg+sizeof(msg), fmt, arg);
va_end(arg);
if(c->trace)
c->trace("tlsError: %s\n", msg);
else if(c->erred)
fprint(2, "double error: %r, %s", msg);
else
werrstr("tls: local %s", msg);
c->erred = 1;
fprint(c->ctl, "alert %d", err);
}
// commit to specific version number
static int
setVersion(TlsConnection *c, int version)
{
if(c->verset || version > MaxProtoVersion || version < MinProtoVersion)
return -1;
if(version > c->version)
version = c->version;
if(version == SSL3Version) {
c->version = version;
c->finished.n = SSL3FinishedLen;
}else if(version == TLSVersion){
c->version = version;
c->finished.n = TLSFinishedLen;
}else
return -1;
c->verset = 1;
return fprint(c->ctl, "version 0x%x", version);
}
// confirm that received Finished message matches the expected value
static int
finishedMatch(TlsConnection *c, Finished *f)
{
return memcmp(f->verify, c->finished.verify, f->n) == 0;
}
// free memory associated with TlsConnection struct
// (but don't close the TLS channel itself)
static void
tlsConnectionFree(TlsConnection *c)
{
tlsSecClose(c->sec);
freebytes(c->sid);
freebytes(c->cert);
memset(c, 0, sizeof(c));
free(c);
}
//================= cipher choices ========================
static int weakCipher[CipherMax] =
{
1, /* TLS_NULL_WITH_NULL_NULL */
1, /* TLS_RSA_WITH_NULL_MD5 */
1, /* TLS_RSA_WITH_NULL_SHA */
1, /* TLS_RSA_EXPORT_WITH_RC4_40_MD5 */
0, /* TLS_RSA_WITH_RC4_128_MD5 */
0, /* TLS_RSA_WITH_RC4_128_SHA */
1, /* TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5 */
0, /* TLS_RSA_WITH_IDEA_CBC_SHA */
1, /* TLS_RSA_EXPORT_WITH_DES40_CBC_SHA */
0, /* TLS_RSA_WITH_DES_CBC_SHA */
0, /* TLS_RSA_WITH_3DES_EDE_CBC_SHA */
1, /* TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA */
0, /* TLS_DH_DSS_WITH_DES_CBC_SHA */
0, /* TLS_DH_DSS_WITH_3DES_EDE_CBC_SHA */
1, /* TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA */
0, /* TLS_DH_RSA_WITH_DES_CBC_SHA */
0, /* TLS_DH_RSA_WITH_3DES_EDE_CBC_SHA */
1, /* TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA */
0, /* TLS_DHE_DSS_WITH_DES_CBC_SHA */
0, /* TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA */
1, /* TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA */
0, /* TLS_DHE_RSA_WITH_DES_CBC_SHA */
0, /* TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA */
1, /* TLS_DH_anon_EXPORT_WITH_RC4_40_MD5 */
1, /* TLS_DH_anon_WITH_RC4_128_MD5 */
1, /* TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA */
1, /* TLS_DH_anon_WITH_DES_CBC_SHA */
1, /* TLS_DH_anon_WITH_3DES_EDE_CBC_SHA */
};
static int
setAlgs(TlsConnection *c, int a)
{
int i;
for(i = 0; i < nelem(cipherAlgs); i++){
if(cipherAlgs[i].tlsid == a){
c->enc = cipherAlgs[i].enc;
c->digest = cipherAlgs[i].digest;
c->nsecret = cipherAlgs[i].nsecret;
if(c->nsecret > MaxKeyData)
return 0;
return 1;
}
}
return 0;
}
static int
okCipher(Ints *cv)
{
int weak, i, j, c;
weak = 1;
for(i = 0; i < cv->len; i++) {
c = cv->data[i];
if(c >= CipherMax)
weak = 0;
else
weak &= weakCipher[c];
for(j = 0; j < nelem(cipherAlgs); j++)
if(cipherAlgs[j].ok && cipherAlgs[j].tlsid == c)
return c;
}
if(weak)
return -2;
return -1;
}
static int
okCompression(Bytes *cv)
{
int i, j, c;
for(i = 0; i < cv->len; i++) {
c = cv->data[i];
for(j = 0; j < nelem(compressors); j++) {
if(compressors[j] == c)
return c;
}
}
return -1;
}
static Lock ciphLock;
static int nciphers;
static int
initCiphers(void)
{
enum {MaxAlgF = 1024, MaxAlgs = 10};
char s[MaxAlgF], *flds[MaxAlgs];
int i, j, n, ok;
lock(&ciphLock);
if(nciphers){
unlock(&ciphLock);
return nciphers;
}
j = open("#a/tls/encalgs", OREAD);
if(j < 0){
werrstr("can't open #a/tls/encalgs: %r");
return 0;
}
n = read(j, s, MaxAlgF-1);
close(j);
if(n <= 0){
werrstr("nothing in #a/tls/encalgs: %r");
return 0;
}
s[n] = 0;
n = getfields(s, flds, MaxAlgs, 1, " \t\r\n");
for(i = 0; i < nelem(cipherAlgs); i++){
ok = 0;
for(j = 0; j < n; j++){
if(strcmp(cipherAlgs[i].enc, flds[j]) == 0){
ok = 1;
break;
}
}
cipherAlgs[i].ok = ok;
}
j = open("#a/tls/hashalgs", OREAD);
if(j < 0){
werrstr("can't open #a/tls/hashalgs: %r");
return 0;
}
n = read(j, s, MaxAlgF-1);
close(j);
if(n <= 0){
werrstr("nothing in #a/tls/hashalgs: %r");
return 0;
}
s[n] = 0;
n = getfields(s, flds, MaxAlgs, 1, " \t\r\n");
for(i = 0; i < nelem(cipherAlgs); i++){
ok = 0;
for(j = 0; j < n; j++){
if(strcmp(cipherAlgs[i].digest, flds[j]) == 0){
ok = 1;
break;
}
}
cipherAlgs[i].ok &= ok;
if(cipherAlgs[i].ok)
nciphers++;
}
unlock(&ciphLock);
return nciphers;
}
static Ints*
makeciphers(void)
{
Ints *is;
int i, j;
is = newints(nciphers);
j = 0;
for(i = 0; i < nelem(cipherAlgs); i++){
if(cipherAlgs[i].ok)
is->data[j++] = cipherAlgs[i].tlsid;
}
return is;
}
//================= security functions ========================
// given X.509 certificate, set up connection to factotum
// for using corresponding private key
static AuthRpc*
factotum_rsa_open(uchar *cert, int certlen)
{
int afd;
char *s;
mpint *pub = nil;
RSApub *rsapub;
AuthRpc *rpc;
// start talking to factotum
if((afd = open("/mnt/factotum/rpc", ORDWR)) < 0)
return nil;
if((rpc = auth_allocrpc(afd)) == nil){
close(afd);
return nil;
}
s = "proto=rsa service=tls role=client";
if(auth_rpc(rpc, "start", s, strlen(s)) != ARok){
factotum_rsa_close(rpc);
return nil;
}
// roll factotum keyring around to match certificate
rsapub = X509toRSApub(cert, certlen, nil, 0);
while(1){
if(auth_rpc(rpc, "read", nil, 0) != ARok){
factotum_rsa_close(rpc);
rpc = nil;
goto done;
}
pub = strtomp(rpc->arg, nil, 16, nil);
assert(pub != nil);
if(mpcmp(pub,rsapub->n) == 0)
break;
}
done:
mpfree(pub);
rsapubfree(rsapub);
return rpc;
}
static mpint*
factotum_rsa_decrypt(AuthRpc *rpc, mpint *cipher)
{
char *p;
int rv;
if((p = mptoa(cipher, 16, nil, 0)) == nil)
return nil;
rv = auth_rpc(rpc, "write", p, strlen(p));
free(p);
if(rv != ARok || auth_rpc(rpc, "read", nil, 0) != ARok)
return nil;
mpfree(cipher);
return strtomp(rpc->arg, nil, 16, nil);
}
static void
factotum_rsa_close(AuthRpc*rpc)
{
if(!rpc)
return;
close(rpc->afd);
auth_freerpc(rpc);
}
static void
tlsPmd5(uchar *buf, int nbuf, uchar *key, int nkey, uchar *label, int nlabel, uchar *seed0, int nseed0, uchar *seed1, int nseed1)
{
uchar ai[MD5dlen], tmp[MD5dlen];
int i, n;
MD5state *s;
// generate a1
s = hmac_md5(label, nlabel, key, nkey, nil, nil);
s = hmac_md5(seed0, nseed0, key, nkey, nil, s);
hmac_md5(seed1, nseed1, key, nkey, ai, s);
while(nbuf > 0) {
s = hmac_md5(ai, MD5dlen, key, nkey, nil, nil);
s = hmac_md5(label, nlabel, key, nkey, nil, s);
s = hmac_md5(seed0, nseed0, key, nkey, nil, s);
hmac_md5(seed1, nseed1, key, nkey, tmp, s);
n = MD5dlen;
if(n > nbuf)
n = nbuf;
for(i = 0; i < n; i++)
buf[i] ^= tmp[i];
buf += n;
nbuf -= n;
hmac_md5(ai, MD5dlen, key, nkey, tmp, nil);
memmove(ai, tmp, MD5dlen);
}
}
static void
tlsPsha1(uchar *buf, int nbuf, uchar *key, int nkey, uchar *label, int nlabel, uchar *seed0, int nseed0, uchar *seed1, int nseed1)
{
uchar ai[SHA1dlen], tmp[SHA1dlen];
int i, n;
SHAstate *s;
// generate a1
s = hmac_sha1(label, nlabel, key, nkey, nil, nil);
s = hmac_sha1(seed0, nseed0, key, nkey, nil, s);
hmac_sha1(seed1, nseed1, key, nkey, ai, s);
while(nbuf > 0) {
s = hmac_sha1(ai, SHA1dlen, key, nkey, nil, nil);
s = hmac_sha1(label, nlabel, key, nkey, nil, s);
s = hmac_sha1(seed0, nseed0, key, nkey, nil, s);
hmac_sha1(seed1, nseed1, key, nkey, tmp, s);
n = SHA1dlen;
if(n > nbuf)
n = nbuf;
for(i = 0; i < n; i++)
buf[i] ^= tmp[i];
buf += n;
nbuf -= n;
hmac_sha1(ai, SHA1dlen, key, nkey, tmp, nil);
memmove(ai, tmp, SHA1dlen);
}
}
// fill buf with md5(args)^sha1(args)
static void
tlsPRF(uchar *buf, int nbuf, uchar *key, int nkey, char *label, uchar *seed0, int nseed0, uchar *seed1, int nseed1)
{
int i;
int nlabel = strlen(label);
int n = (nkey + 1) >> 1;
for(i = 0; i < nbuf; i++)
buf[i] = 0;
tlsPmd5(buf, nbuf, key, n, (uchar*)label, nlabel, seed0, nseed0, seed1, nseed1);
tlsPsha1(buf, nbuf, key+nkey-n, n, (uchar*)label, nlabel, seed0, nseed0, seed1, nseed1);
}
/*
* for setting server session id's
*/
static Lock sidLock;
static long maxSid = 1;
/* the keys are verified to have the same public components
* and to function correctly with pkcs 1 encryption and decryption. */
static TlsSec*
tlsSecInits(int cvers, uchar *csid, int ncsid, uchar *crandom, uchar *ssid, int *nssid, uchar *srandom)
{
TlsSec *sec = emalloc(sizeof(*sec));
USED(csid); USED(ncsid); // ignore csid for now
memmove(sec->crandom, crandom, RandomSize);
sec->clientVers = cvers;
put32(sec->srandom, time(0));
genrandom(sec->srandom+4, RandomSize-4);
memmove(srandom, sec->srandom, RandomSize);
/*
* make up a unique sid: use our pid, and and incrementing id
* can signal no sid by setting nssid to 0.
*/
memset(ssid, 0, SidSize);
put32(ssid, getpid());
lock(&sidLock);
put32(ssid+4, maxSid++);
unlock(&sidLock);
*nssid = SidSize;
return sec;
}
static int
tlsSecSecrets(TlsSec *sec, int vers, uchar *epm, int nepm, uchar *kd, int nkd)
{
if(epm != nil){
if(setVers(sec, vers) < 0)
goto Err;
serverMasterSecret(sec, epm, nepm);
}else if(sec->vers != vers){
werrstr("mismatched session versions");
goto Err;
}
setSecrets(sec, kd, nkd);
return 0;
Err:
sec->ok = -1;
return -1;
}
static TlsSec*
tlsSecInitc(int cvers, uchar *crandom)
{
TlsSec *sec = emalloc(sizeof(*sec));
sec->clientVers = cvers;
put32(sec->crandom, time(0));
genrandom(sec->crandom+4, RandomSize-4);
memmove(crandom, sec->crandom, RandomSize);
return sec;
}
static int
tlsSecSecretc(TlsSec *sec, uchar *sid, int nsid, uchar *srandom, uchar *cert, int ncert, int vers, uchar **epm, int *nepm, uchar *kd, int nkd)
{
RSApub *pub;
pub = nil;
USED(sid);
USED(nsid);
memmove(sec->srandom, srandom, RandomSize);
if(setVers(sec, vers) < 0)
goto Err;
pub = X509toRSApub(cert, ncert, nil, 0);
if(pub == nil){
werrstr("invalid x509/rsa certificate");
goto Err;
}
if(clientMasterSecret(sec, pub, epm, nepm) < 0)
goto Err;
rsapubfree(pub);
setSecrets(sec, kd, nkd);
return 0;
Err:
if(pub != nil)
rsapubfree(pub);
sec->ok = -1;
return -1;
}
static int
tlsSecFinished(TlsSec *sec, MD5state md5, SHAstate sha1, uchar *fin, int nfin, int isclient)
{
if(sec->nfin != nfin){
sec->ok = -1;
werrstr("invalid finished exchange");
return -1;
}
md5.malloced = 0;
sha1.malloced = 0;
(*sec->setFinished)(sec, md5, sha1, fin, isclient);
return 1;
}
static void
tlsSecOk(TlsSec *sec)
{
if(sec->ok == 0)
sec->ok = 1;
}
static void
tlsSecKill(TlsSec *sec)
{
if(!sec)
return;
factotum_rsa_close(sec->rpc);
sec->ok = -1;
}
static void
tlsSecClose(TlsSec *sec)
{
if(!sec)
return;
factotum_rsa_close(sec->rpc);
free(sec->server);
free(sec);
}
static int
setVers(TlsSec *sec, int v)
{
if(v == SSL3Version){
sec->setFinished = sslSetFinished;
sec->nfin = SSL3FinishedLen;
sec->prf = sslPRF;
}else if(v == TLSVersion){
sec->setFinished = tlsSetFinished;
sec->nfin = TLSFinishedLen;
sec->prf = tlsPRF;
}else{
werrstr("invalid version");
return -1;
}
sec->vers = v;
return 0;
}
/*
* generate secret keys from the master secret.
*
* different crypto selections will require different amounts
* of key expansion and use of key expansion data,
* but it's all generated using the same function.
*/
static void
setSecrets(TlsSec *sec, uchar *kd, int nkd)
{
(*sec->prf)(kd, nkd, sec->sec, MasterSecretSize, "key expansion",
sec->srandom, RandomSize, sec->crandom, RandomSize);
}
/*
* set the master secret from the pre-master secret.
*/
static void
setMasterSecret(TlsSec *sec, Bytes *pm)
{
(*sec->prf)(sec->sec, MasterSecretSize, pm->data, MasterSecretSize, "master secret",
sec->crandom, RandomSize, sec->srandom, RandomSize);
}
static void
serverMasterSecret(TlsSec *sec, uchar *epm, int nepm)
{
Bytes *pm;
pm = pkcs1_decrypt(sec, epm, nepm);
// if the client messed up, just continue as if everything is ok,
// to prevent attacks to check for correctly formatted messages.
// Hence the fprint(2,) can't be replaced by tlsError(), which sends an Alert msg to the client.
if(sec->ok < 0 || pm == nil || get16(pm->data) != sec->clientVers){
fprint(2, "serverMasterSecret failed ok=%d pm=%p pmvers=%x cvers=%x nepm=%d\n",
sec->ok, pm, pm ? get16(pm->data) : -1, sec->clientVers, nepm);
sec->ok = -1;
if(pm != nil)
freebytes(pm);
pm = newbytes(MasterSecretSize);
genrandom(pm->data, MasterSecretSize);
}
setMasterSecret(sec, pm);
memset(pm->data, 0, pm->len);
freebytes(pm);
}
static int
clientMasterSecret(TlsSec *sec, RSApub *pub, uchar **epm, int *nepm)
{
Bytes *pm, *key;
pm = newbytes(MasterSecretSize);
put16(pm->data, sec->clientVers);
genrandom(pm->data+2, MasterSecretSize - 2);
setMasterSecret(sec, pm);
key = pkcs1_encrypt(pm, pub, 2);
memset(pm->data, 0, pm->len);
freebytes(pm);
if(key == nil){
werrstr("tls pkcs1_encrypt failed");
return -1;
}
*nepm = key->len;
*epm = malloc(*nepm);
if(*epm == nil){
freebytes(key);
werrstr("out of memory");
return -1;
}
memmove(*epm, key->data, *nepm);
freebytes(key);
return 1;
}
static void
sslSetFinished(TlsSec *sec, MD5state hsmd5, SHAstate hssha1, uchar *finished, int isClient)
{
DigestState *s;
uchar h0[MD5dlen], h1[SHA1dlen], pad[48];
char *label;
if(isClient)
label = "CLNT";
else
label = "SRVR";
md5((uchar*)label, 4, nil, &hsmd5);
md5(sec->sec, MasterSecretSize, nil, &hsmd5);
memset(pad, 0x36, 48);
md5(pad, 48, nil, &hsmd5);
md5(nil, 0, h0, &hsmd5);
memset(pad, 0x5C, 48);
s = md5(sec->sec, MasterSecretSize, nil, nil);
s = md5(pad, 48, nil, s);
md5(h0, MD5dlen, finished, s);
sha1((uchar*)label, 4, nil, &hssha1);
sha1(sec->sec, MasterSecretSize, nil, &hssha1);
memset(pad, 0x36, 40);
sha1(pad, 40, nil, &hssha1);
sha1(nil, 0, h1, &hssha1);
memset(pad, 0x5C, 40);
s = sha1(sec->sec, MasterSecretSize, nil, nil);
s = sha1(pad, 40, nil, s);
sha1(h1, SHA1dlen, finished + MD5dlen, s);
}
// fill "finished" arg with md5(args)^sha1(args)
static void
tlsSetFinished(TlsSec *sec, MD5state hsmd5, SHAstate hssha1, uchar *finished, int isClient)
{
uchar h0[MD5dlen], h1[SHA1dlen];
char *label;
// get current hash value, but allow further messages to be hashed in
md5(nil, 0, h0, &hsmd5);
sha1(nil, 0, h1, &hssha1);
if(isClient)
label = "client finished";
else
label = "server finished";
tlsPRF(finished, TLSFinishedLen, sec->sec, MasterSecretSize, label, h0, MD5dlen, h1, SHA1dlen);
}
static void
sslPRF(uchar *buf, int nbuf, uchar *key, int nkey, char *label, uchar *seed0, int nseed0, uchar *seed1, int nseed1)
{
DigestState *s;
uchar sha1dig[SHA1dlen], md5dig[MD5dlen], tmp[26];
int i, n, len;
USED(label);
len = 1;
while(nbuf > 0){
if(len > 26)
return;
for(i = 0; i < len; i++)
tmp[i] = 'A' - 1 + len;
s = sha1(tmp, len, nil, nil);
s = sha1(key, nkey, nil, s);
s = sha1(seed0, nseed0, nil, s);
sha1(seed1, nseed1, sha1dig, s);
s = md5(key, nkey, nil, nil);
md5(sha1dig, SHA1dlen, md5dig, s);
n = MD5dlen;
if(n > nbuf)
n = nbuf;
memmove(buf, md5dig, n);
buf += n;
nbuf -= n;
len++;
}
}
static mpint*
bytestomp(Bytes* bytes)
{
mpint* ans;
ans = betomp(bytes->data, bytes->len, nil);
return ans;
}
/*
* Convert mpint* to Bytes, putting high order byte first.
*/
static Bytes*
mptobytes(mpint* big)
{
int n, m;
uchar *a;
Bytes* ans;
n = (mpsignif(big)+7)/8;
m = mptobe(big, nil, n, &a);
ans = makebytes(a, m);
return ans;
}
// Do RSA computation on block according to key, and pad
// result on left with zeros to make it modlen long.
static Bytes*
rsacomp(Bytes* block, RSApub* key, int modlen)
{
mpint *x, *y;
Bytes *a, *ybytes;
int ylen;
x = bytestomp(block);
y = rsaencrypt(key, x, nil);
mpfree(x);
ybytes = mptobytes(y);
ylen = ybytes->len;
if(ylen < modlen) {
a = newbytes(modlen);
memset(a->data, 0, modlen-ylen);
memmove(a->data+modlen-ylen, ybytes->data, ylen);
freebytes(ybytes);
ybytes = a;
}
else if(ylen > modlen) {
// assume it has leading zeros (mod should make it so)
a = newbytes(modlen);
memmove(a->data, ybytes->data, modlen);
freebytes(ybytes);
ybytes = a;
}
mpfree(y);
return ybytes;
}
// encrypt data according to PKCS#1, /lib/rfc/rfc2437 9.1.2.1
static Bytes*
pkcs1_encrypt(Bytes* data, RSApub* key, int blocktype)
{
Bytes *pad, *eb, *ans;
int i, dlen, padlen, modlen;
modlen = (mpsignif(key->n)+7)/8;
dlen = data->len;
if(modlen < 12 || dlen > modlen - 11)
return nil;
padlen = modlen - 3 - dlen;
pad = newbytes(padlen);
genrandom(pad->data, padlen);
for(i = 0; i < padlen; i++) {
if(blocktype == 0)
pad->data[i] = 0;
else if(blocktype == 1)
pad->data[i] = 255;
else if(pad->data[i] == 0)
pad->data[i] = 1;
}
eb = newbytes(modlen);
eb->data[0] = 0;
eb->data[1] = blocktype;
memmove(eb->data+2, pad->data, padlen);
eb->data[padlen+2] = 0;
memmove(eb->data+padlen+3, data->data, dlen);
ans = rsacomp(eb, key, modlen);
freebytes(eb);
freebytes(pad);
return ans;
}
// decrypt data according to PKCS#1, with given key.
// expect a block type of 2.
static Bytes*
pkcs1_decrypt(TlsSec *sec, uchar *epm, int nepm)
{
Bytes *eb, *ans = nil;
int i, modlen;
mpint *x, *y;
modlen = (mpsignif(sec->rsapub->n)+7)/8;
if(nepm != modlen)
return nil;
x = betomp(epm, nepm, nil);
y = factotum_rsa_decrypt(sec->rpc, x);
if(y == nil)
return nil;
eb = mptobytes(y);
if(eb->len < modlen){ // pad on left with zeros
ans = newbytes(modlen);
memset(ans->data, 0, modlen-eb->len);
memmove(ans->data+modlen-eb->len, eb->data, eb->len);
freebytes(eb);
eb = ans;
}
if(eb->data[0] == 0 && eb->data[1] == 2) {
for(i = 2; i < modlen; i++)
if(eb->data[i] == 0)
break;
if(i < modlen - 1)
ans = makebytes(eb->data+i+1, modlen-(i+1));
}
freebytes(eb);
return ans;
}
//================= general utility functions ========================
static void *
emalloc(int n)
{
void *p;
if(n==0)
n=1;
p = malloc(n);
if(p == nil){
exits("out of memory");
}
memset(p, 0, n);
return p;
}
static void *
erealloc(void *ReallocP, int ReallocN)
{
if(ReallocN == 0)
ReallocN = 1;
if(!ReallocP)
ReallocP = emalloc(ReallocN);
else if(!(ReallocP = realloc(ReallocP, ReallocN))){
exits("out of memory");
}
return(ReallocP);
}
static void
put32(uchar *p, u32int x)
{
p[0] = x>>24;
p[1] = x>>16;
p[2] = x>>8;
p[3] = x;
}
static void
put24(uchar *p, int x)
{
p[0] = x>>16;
p[1] = x>>8;
p[2] = x;
}
static void
put16(uchar *p, int x)
{
p[0] = x>>8;
p[1] = x;
}
static u32int
get32(uchar *p)
{
return (p[0]<<24)|(p[1]<<16)|(p[2]<<8)|p[3];
}
static int
get24(uchar *p)
{
return (p[0]<<16)|(p[1]<<8)|p[2];
}
static int
get16(uchar *p)
{
return (p[0]<<8)|p[1];
}
/* ANSI offsetof() */
#define OFFSET(x, s) ((int)(&(((s*)0)->x)))
/*
* malloc and return a new Bytes structure capable of
* holding len bytes. (len >= 0)
* Used to use crypt_malloc, which aborts if malloc fails.
*/
static Bytes*
newbytes(int len)
{
Bytes* ans;
ans = (Bytes*)malloc(OFFSET(data[0], Bytes) + len);
ans->len = len;
return ans;
}
/*
* newbytes(len), with data initialized from buf
*/
static Bytes*
makebytes(uchar* buf, int len)
{
Bytes* ans;
ans = newbytes(len);
memmove(ans->data, buf, len);
return ans;
}
static void
freebytes(Bytes* b)
{
if(b != nil)
free(b);
}
/* len is number of ints */
static Ints*
newints(int len)
{
Ints* ans;
ans = (Ints*)malloc(OFFSET(data[0], Ints) + len*sizeof(int));
ans->len = len;
return ans;
}
static Ints*
makeints(int* buf, int len)
{
Ints* ans;
ans = newints(len);
if(len > 0)
memmove(ans->data, buf, len*sizeof(int));
return ans;
}
static void
freeints(Ints* b)
{
if(b != nil)
free(b);
}
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