embedaddon/ntp/ntpd/ntp_crypto.c - view

File: [ELWIX - Embedded LightWeight unIX -] / embedaddon / ntp / ntpd / ntp_crypto.c
Revision 1.1.1.1 (vendor branch): download - view: text, annotated - select for diffs - revision graph
Tue May 29 12:08:37 2012 UTC (12 years, 7 months ago) by misho
Branches: ntp, MAIN
CVS tags: v4_2_6p5p0, v4_2_6p5, HEAD

ntp 4.2.6p5

/* * ntp_crypto.c - NTP version 4 public key routines */ #ifdef HAVE_CONFIG_H #include <config.h> #endif #ifdef OPENSSL #include <stdio.h> #include <sys/types.h> #include <sys/param.h> #include <unistd.h> #include <fcntl.h> #include "ntpd.h" #include "ntp_stdlib.h" #include "ntp_unixtime.h" #include "ntp_string.h" #include "ntp_random.h" #include "ntp_assert.h" #include "openssl/asn1_mac.h" #include "openssl/bn.h" #include "openssl/err.h" #include "openssl/evp.h" #include "openssl/pem.h" #include "openssl/rand.h" #include "openssl/x509v3.h" #ifdef KERNEL_PLL #include "ntp_syscall.h" #endif /* KERNEL_PLL */ /* * Extension field message format * * These are always signed and saved before sending in network byte * order. They must be converted to and from host byte order for * processing. * * +-------+-------+ * | op | len | <- extension pointer * +-------+-------+ * | associd | * +---------------+ * | timestamp | <- value pointer * +---------------+ * | filestamp | * +---------------+ * | value len | * +---------------+ * | | * = value = * | | * +---------------+ * | signature len | * +---------------+ * | | * = signature = * | | * +---------------+ * * The CRYPTO_RESP bit is set to 0 for requests, 1 for responses. * Requests carry the association ID of the receiver; responses carry * the association ID of the sender. Some messages include only the * operation/length and association ID words and so have length 8 * octets. Ohers include the value structure and associated value and * signature fields. These messages include the timestamp, filestamp, * value and signature words and so have length at least 24 octets. The * signature and/or value fields can be empty, in which case the * respective length words are zero. An empty value with nonempty * signature is syntactically valid, but semantically questionable. * * The filestamp represents the time when a cryptographic data file such * as a public/private key pair is created. It follows every reference * depending on that file and serves as a means to obsolete earlier data * of the same type. The timestamp represents the time when the * cryptographic data of the message were last signed. Creation of a * cryptographic data file or signing a message can occur only when the * creator or signor is synchronized to an authoritative source and * proventicated to a trusted authority. * * Note there are several conditions required for server trust. First, * the public key on the server certificate must be verified, which can * involve a hike along the certificate trail to a trusted host. Next, * the server trust must be confirmed by one of several identity * schemes. Valid cryptographic values are signed with attached * timestamp and filestamp. Individual packet trust is confirmed * relative to these values by a message digest with keys generated by a * reverse-order pseudorandom hash. * * State decomposition. These flags are lit in the order given. They are * dim only when the association is demobilized. * * CRYPTO_FLAG_ENAB Lit upon acceptance of a CRYPTO_ASSOC message * CRYPTO_FLAG_CERT Lit when a self-digned trusted certificate is * accepted. * CRYPTO_FLAG_VRFY Lit when identity is confirmed. * CRYPTO_FLAG_PROV Lit when the first signature is verified. * CRYPTO_FLAG_COOK Lit when a valid cookie is accepted. * CRYPTO_FLAG_AUTO Lit when valid autokey values are accepted. * CRYPTO_FLAG_SIGN Lit when the server signed certificate is * accepted. * CRYPTO_FLAG_LEAP Lit when the leapsecond values are accepted. */ /* * Cryptodefines */ #define TAI_1972 10 /* initial TAI offset (s) */ #define MAX_LEAP 100 /* max UTC leapseconds (s) */ #define VALUE_LEN (6 * 4) /* min response field length */ #define YEAR (60 * 60 * 24 * 365) /* seconds in year */ /* * Global cryptodata in host byte order */ u_int32 crypto_flags = 0x0; /* status word */ int crypto_nid = KEY_TYPE_MD5; /* digest nid */ char *sys_hostname = NULL; /* host name */ char *sys_groupname = NULL; /* group name */ /* * Global cryptodata in network byte order */ struct cert_info *cinfo = NULL; /* certificate info/value cache */ struct cert_info *cert_host = NULL; /* host certificate */ struct pkey_info *pkinfo = NULL; /* key info/value cache */ struct value hostval; /* host value */ struct value pubkey; /* public key */ struct value tai_leap; /* leapseconds values */ struct pkey_info *iffkey_info = NULL; /* IFF keys */ struct pkey_info *gqkey_info = NULL; /* GQ keys */ struct pkey_info *mvkey_info = NULL; /* MV keys */ /* * Private cryptodata in host byte order */ static char *passwd = NULL; /* private key password */ static EVP_PKEY *host_pkey = NULL; /* host key */ static EVP_PKEY *sign_pkey = NULL; /* sign key */ static const EVP_MD *sign_digest = NULL; /* sign digest */ static u_int sign_siglen; /* sign key length */ static char *rand_file = NULL; /* random seed file */ /* * Cryptotypes */ static int crypto_verify (struct exten *, struct value *, struct peer *); static int crypto_encrypt (struct exten *, struct value *, keyid_t *); static int crypto_alice (struct peer *, struct value *); static int crypto_alice2 (struct peer *, struct value *); static int crypto_alice3 (struct peer *, struct value *); static int crypto_bob (struct exten *, struct value *); static int crypto_bob2 (struct exten *, struct value *); static int crypto_bob3 (struct exten *, struct value *); static int crypto_iff (struct exten *, struct peer *); static int crypto_gq (struct exten *, struct peer *); static int crypto_mv (struct exten *, struct peer *); static int crypto_send (struct exten *, struct value *, int); static tstamp_t crypto_time (void); static u_long asn2ntp (ASN1_TIME *); static struct cert_info *cert_parse (u_char *, long, tstamp_t); static int cert_sign (struct exten *, struct value *); static struct cert_info *cert_install (struct exten *, struct peer *); static int cert_hike (struct peer *, struct cert_info *); static void cert_free (struct cert_info *); static struct pkey_info *crypto_key (char *, char *, sockaddr_u *); static void bighash (BIGNUM *, BIGNUM *); static struct cert_info *crypto_cert (char *); #ifdef SYS_WINNT int readlink(char * link, char * file, int len) { return (-1); } #endif /* * session_key - generate session key * * This routine generates a session key from the source address, * destination address, key ID and private value. The value of the * session key is the MD5 hash of these values, while the next key ID is * the first four octets of the hash. * * Returns the next key ID or 0 if there is no destination address. */ keyid_t session_key( sockaddr_u *srcadr, /* source address */ sockaddr_u *dstadr, /* destination address */ keyid_t keyno, /* key ID */ keyid_t private, /* private value */ u_long lifetime /* key lifetime */ ) { EVP_MD_CTX ctx; /* message digest context */ u_char dgst[EVP_MAX_MD_SIZE]; /* message digest */ keyid_t keyid; /* key identifer */ u_int32 header[10]; /* data in network byte order */ u_int hdlen, len; if (!dstadr) return 0; /* * Generate the session key and key ID. If the lifetime is * greater than zero, install the key and call it trusted. */ hdlen = 0; switch(AF(srcadr)) { case AF_INET: header[0] = NSRCADR(srcadr); header[1] = NSRCADR(dstadr); header[2] = htonl(keyno); header[3] = htonl(private); hdlen = 4 * sizeof(u_int32); break; case AF_INET6: memcpy(&header[0], PSOCK_ADDR6(srcadr), sizeof(struct in6_addr)); memcpy(&header[4], PSOCK_ADDR6(dstadr), sizeof(struct in6_addr)); header[8] = htonl(keyno); header[9] = htonl(private); hdlen = 10 * sizeof(u_int32); break; } EVP_DigestInit(&ctx, EVP_get_digestbynid(crypto_nid)); EVP_DigestUpdate(&ctx, (u_char *)header, hdlen); EVP_DigestFinal(&ctx, dgst, &len); memcpy(&keyid, dgst, 4); keyid = ntohl(keyid); if (lifetime != 0) { MD5auth_setkey(keyno, crypto_nid, dgst, len); authtrust(keyno, lifetime); } DPRINTF(2, ("session_key: %s > %s %08x %08x hash %08x life %lu\n", stoa(srcadr), stoa(dstadr), keyno, private, keyid, lifetime)); return (keyid); } /* * make_keylist - generate key list * * Returns * XEVNT_OK success * XEVNT_ERR protocol error * * This routine constructs a pseudo-random sequence by repeatedly * hashing the session key starting from a given source address, * destination address, private value and the next key ID of the * preceeding session key. The last entry on the list is saved along * with its sequence number and public signature. */ int make_keylist( struct peer *peer, /* peer structure pointer */ struct interface *dstadr /* interface */ ) { EVP_MD_CTX ctx; /* signature context */ tstamp_t tstamp; /* NTP timestamp */ struct autokey *ap; /* autokey pointer */ struct value *vp; /* value pointer */ keyid_t keyid = 0; /* next key ID */ keyid_t cookie; /* private value */ long lifetime; u_int len, mpoll; int i; if (!dstadr) return XEVNT_ERR; /* * Allocate the key list if necessary. */ tstamp = crypto_time(); if (peer->keylist == NULL) peer->keylist = emalloc(sizeof(keyid_t) * NTP_MAXSESSION); /* * Generate an initial key ID which is unique and greater than * NTP_MAXKEY. */ while (1) { keyid = ntp_random() & 0xffffffff; if (keyid <= NTP_MAXKEY) continue; if (authhavekey(keyid)) continue; break; } /* * Generate up to NTP_MAXSESSION session keys. Stop if the * next one would not be unique or not a session key ID or if * it would expire before the next poll. The private value * included in the hash is zero if broadcast mode, the peer * cookie if client mode or the host cookie if symmetric modes. */ mpoll = 1 << min(peer->ppoll, peer->hpoll); lifetime = min(1 << sys_automax, NTP_MAXSESSION * mpoll); if (peer->hmode == MODE_BROADCAST) cookie = 0; else cookie = peer->pcookie; for (i = 0; i < NTP_MAXSESSION; i++) { peer->keylist[i] = keyid; peer->keynumber = i; keyid = session_key(&dstadr->sin, &peer->srcadr, keyid, cookie, lifetime + mpoll); lifetime -= mpoll; if (auth_havekey(keyid) || keyid <= NTP_MAXKEY || lifetime < 0 || tstamp == 0) break; } /* * Save the last session key ID, sequence number and timestamp, * then sign these values for later retrieval by the clients. Be * careful not to use invalid key media. Use the public values * timestamp as filestamp. */ vp = &peer->sndval; if (vp->ptr == NULL) vp->ptr = emalloc(sizeof(struct autokey)); ap = (struct autokey *)vp->ptr; ap->seq = htonl(peer->keynumber); ap->key = htonl(keyid); vp->tstamp = htonl(tstamp); vp->fstamp = hostval.tstamp; vp->vallen = htonl(sizeof(struct autokey)); vp->siglen = 0; if (tstamp != 0) { if (vp->sig == NULL) vp->sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)vp, 12); EVP_SignUpdate(&ctx, vp->ptr, sizeof(struct autokey)); if (EVP_SignFinal(&ctx, vp->sig, &len, sign_pkey)) { vp->siglen = htonl(sign_siglen); peer->flags |= FLAG_ASSOC; } } #ifdef DEBUG if (debug) printf("make_keys: %d %08x %08x ts %u fs %u poll %d\n", peer->keynumber, keyid, cookie, ntohl(vp->tstamp), ntohl(vp->fstamp), peer->hpoll); #endif return (XEVNT_OK); } /* * crypto_recv - parse extension fields * * This routine is called when the packet has been matched to an * association and passed sanity, format and MAC checks. We believe the * extension field values only if the field has proper format and * length, the timestamp and filestamp are valid and the signature has * valid length and is verified. There are a few cases where some values * are believed even if the signature fails, but only if the proventic * bit is not set. * * Returns * XEVNT_OK success * XEVNT_ERR protocol error * XEVNT_LEN bad field format or length */ int crypto_recv( struct peer *peer, /* peer structure pointer */ struct recvbuf *rbufp /* packet buffer pointer */ ) { const EVP_MD *dp; /* message digest algorithm */ u_int32 *pkt; /* receive packet pointer */ struct autokey *ap, *bp; /* autokey pointer */ struct exten *ep, *fp; /* extension pointers */ struct cert_info *xinfo; /* certificate info pointer */ int has_mac; /* length of MAC field */ int authlen; /* offset of MAC field */ associd_t associd; /* association ID */ tstamp_t tstamp = 0; /* timestamp */ tstamp_t fstamp = 0; /* filestamp */ u_int len; /* extension field length */ u_int code; /* extension field opcode */ u_int vallen = 0; /* value length */ X509 *cert; /* X509 certificate */ char statstr[NTP_MAXSTRLEN]; /* statistics for filegen */ keyid_t cookie; /* crumbles */ int hismode; /* packet mode */ int rval = XEVNT_OK; u_char *ptr; u_int32 temp32; /* * Initialize. Note that the packet has already been checked for * valid format and extension field lengths. First extract the * field length, command code and association ID in host byte * order. These are used with all commands and modes. Then check * the version number, which must be 2, and length, which must * be at least 8 for requests and VALUE_LEN (24) for responses. * Packets that fail either test sink without a trace. The * association ID is saved only if nonzero. */ authlen = LEN_PKT_NOMAC; hismode = (int)PKT_MODE((&rbufp->recv_pkt)->li_vn_mode); while ((has_mac = rbufp->recv_length - authlen) > MAX_MAC_LEN) { pkt = (u_int32 *)&rbufp->recv_pkt + authlen / 4; ep = (struct exten *)pkt; code = ntohl(ep->opcode) & 0xffff0000; len = ntohl(ep->opcode) & 0x0000ffff; associd = (associd_t)ntohl(pkt[1]); rval = XEVNT_OK; #ifdef DEBUG if (debug) printf( "crypto_recv: flags 0x%x ext offset %d len %u code 0x%x associd %d\n", peer->crypto, authlen, len, code >> 16, associd); #endif /* * Check version number and field length. If bad, * quietly ignore the packet. */ if (((code >> 24) & 0x3f) != CRYPTO_VN || len < 8) { sys_badlength++; code |= CRYPTO_ERROR; } if (len >= VALUE_LEN) { tstamp = ntohl(ep->tstamp); fstamp = ntohl(ep->fstamp); vallen = ntohl(ep->vallen); } switch (code) { /* * Install status word, host name, signature scheme and * association ID. In OpenSSL the signature algorithm is * bound to the digest algorithm, so the NID completely * defines the signature scheme. Note the request and * response are identical, but neither is validated by * signature. The request is processed here only in * symmetric modes. The server name field might be * useful to implement access controls in future. */ case CRYPTO_ASSOC: /* * If our state machine is running when this * message arrives, the other fellow might have * restarted. However, this could be an * intruder, so just clamp the poll interval and * find out for ourselves. Otherwise, pass the * extension field to the transmit side. */ if (peer->crypto & CRYPTO_FLAG_CERT) { rval = XEVNT_ERR; break; } if (peer->cmmd) { if (peer->assoc != associd) { rval = XEVNT_ERR; break; } } fp = emalloc(len); memcpy(fp, ep, len); fp->associd = htonl(peer->associd); peer->cmmd = fp; /* fall through */ case CRYPTO_ASSOC | CRYPTO_RESP: /* * Discard the message if it has already been * stored or the message has been amputated. */ if (peer->crypto) { if (peer->assoc != associd) rval = XEVNT_ERR; break; } if (vallen == 0 || vallen > MAXHOSTNAME || len < VALUE_LEN + vallen) { rval = XEVNT_LEN; break; } #ifdef DEBUG if (debug) printf( "crypto_recv: ident host 0x%x %d server 0x%x %d\n", crypto_flags, peer->associd, fstamp, peer->assoc); #endif temp32 = crypto_flags & CRYPTO_FLAG_MASK; /* * If the client scheme is PC, the server scheme * must be PC. The public key and identity are * presumed valid, so we skip the certificate * and identity exchanges and move immediately * to the cookie exchange which confirms the * server signature. */ if (crypto_flags & CRYPTO_FLAG_PRIV) { if (!(fstamp & CRYPTO_FLAG_PRIV)) { rval = XEVNT_KEY; break; } fstamp |= CRYPTO_FLAG_CERT | CRYPTO_FLAG_VRFY | CRYPTO_FLAG_SIGN; /* * It is an error if either peer supports * identity, but the other does not. */ } else if (hismode == MODE_ACTIVE || hismode == MODE_PASSIVE) { if ((temp32 && !(fstamp & CRYPTO_FLAG_MASK)) || (!temp32 && (fstamp & CRYPTO_FLAG_MASK))) { rval = XEVNT_KEY; break; } } /* * Discard the message if the signature digest * NID is not supported. */ temp32 = (fstamp >> 16) & 0xffff; dp = (const EVP_MD *)EVP_get_digestbynid(temp32); if (dp == NULL) { rval = XEVNT_MD; break; } /* * Save status word, host name and message * digest/signature type. If this is from a * broadcast and the association ID has changed, * request the autokey values. */ peer->assoc = associd; if (hismode == MODE_SERVER) fstamp |= CRYPTO_FLAG_AUTO; if (!(fstamp & CRYPTO_FLAG_TAI)) fstamp |= CRYPTO_FLAG_LEAP; RAND_bytes((u_char *)&peer->hcookie, 4); peer->crypto = fstamp; peer->digest = dp; if (peer->subject != NULL) free(peer->subject); peer->subject = emalloc(vallen + 1); memcpy(peer->subject, ep->pkt, vallen); peer->subject[vallen] = '\0'; if (peer->issuer != NULL) free(peer->issuer); peer->issuer = emalloc(vallen + 1); strcpy(peer->issuer, peer->subject); snprintf(statstr, NTP_MAXSTRLEN, "assoc %d %d host %s %s", peer->associd, peer->assoc, peer->subject, OBJ_nid2ln(temp32)); record_crypto_stats(&peer->srcadr, statstr); #ifdef DEBUG if (debug) printf("crypto_recv: %s\n", statstr); #endif break; /* * Decode X509 certificate in ASN.1 format and extract * the data containing, among other things, subject * name and public key. In the default identification * scheme, the certificate trail is followed to a self * signed trusted certificate. */ case CRYPTO_CERT | CRYPTO_RESP: /* * Discard the message if empty or invalid. */ if (len < VALUE_LEN) break; if ((rval = crypto_verify(ep, NULL, peer)) != XEVNT_OK) break; /* * Scan the certificate list to delete old * versions and link the newest version first on * the list. Then, verify the signature. If the * certificate is bad or missing, just ignore * it. */ if ((xinfo = cert_install(ep, peer)) == NULL) { rval = XEVNT_CRT; break; } if ((rval = cert_hike(peer, xinfo)) != XEVNT_OK) break; /* * We plug in the public key and lifetime from * the first certificate received. However, note * that this certificate might not be signed by * the server, so we can't check the * signature/digest NID. */ if (peer->pkey == NULL) { ptr = (u_char *)xinfo->cert.ptr; cert = d2i_X509(NULL, &ptr, ntohl(xinfo->cert.vallen)); peer->pkey = X509_get_pubkey(cert); X509_free(cert); } peer->flash &= ~TEST8; temp32 = xinfo->nid; snprintf(statstr, NTP_MAXSTRLEN, "cert %s %s 0x%x %s (%u) fs %u", xinfo->subject, xinfo->issuer, xinfo->flags, OBJ_nid2ln(temp32), temp32, ntohl(ep->fstamp)); record_crypto_stats(&peer->srcadr, statstr); #ifdef DEBUG if (debug) printf("crypto_recv: %s\n", statstr); #endif break; /* * Schnorr (IFF) identity scheme. This scheme is * designed for use with shared secret server group keys * and where the certificate may be generated by a third * party. The client sends a challenge to the server, * which performs a calculation and returns the result. * A positive result is possible only if both client and * server contain the same secret group key. */ case CRYPTO_IFF | CRYPTO_RESP: /* * Discard the message if invalid. */ if ((rval = crypto_verify(ep, NULL, peer)) != XEVNT_OK) break; /* * If the challenge matches the response, the * server public key, signature and identity are * all verified at the same time. The server is * declared trusted, so we skip further * certificate exchanges and move immediately to * the cookie exchange. */ if ((rval = crypto_iff(ep, peer)) != XEVNT_OK) break; peer->crypto |= CRYPTO_FLAG_VRFY; peer->flash &= ~TEST8; snprintf(statstr, NTP_MAXSTRLEN, "iff %s fs %u", peer->issuer, ntohl(ep->fstamp)); record_crypto_stats(&peer->srcadr, statstr); #ifdef DEBUG if (debug) printf("crypto_recv: %s\n", statstr); #endif break; /* * Guillou-Quisquater (GQ) identity scheme. This scheme * is designed for use with public certificates carrying * the GQ public key in an extension field. The client * sends a challenge to the server, which performs a * calculation and returns the result. A positive result * is possible only if both client and server contain * the same group key and the server has the matching GQ * private key. */ case CRYPTO_GQ | CRYPTO_RESP: /* * Discard the message if invalid */ if ((rval = crypto_verify(ep, NULL, peer)) != XEVNT_OK) break; /* * If the challenge matches the response, the * server public key, signature and identity are * all verified at the same time. The server is * declared trusted, so we skip further * certificate exchanges and move immediately to * the cookie exchange. */ if ((rval = crypto_gq(ep, peer)) != XEVNT_OK) break; peer->crypto |= CRYPTO_FLAG_VRFY; peer->flash &= ~TEST8; snprintf(statstr, NTP_MAXSTRLEN, "gq %s fs %u", peer->issuer, ntohl(ep->fstamp)); record_crypto_stats(&peer->srcadr, statstr); #ifdef DEBUG if (debug) printf("crypto_recv: %s\n", statstr); #endif break; /* * Mu-Varadharajan (MV) identity scheme. This scheme is * designed for use with three levels of trust, trusted * host, server and client. The trusted host key is * opaque to servers and clients; the server keys are * opaque to clients and each client key is different. * Client keys can be revoked without requiring new key * generations. */ case CRYPTO_MV | CRYPTO_RESP: /* * Discard the message if invalid. */ if ((rval = crypto_verify(ep, NULL, peer)) != XEVNT_OK) break; /* * If the challenge matches the response, the * server public key, signature and identity are * all verified at the same time. The server is * declared trusted, so we skip further * certificate exchanges and move immediately to * the cookie exchange. */ if ((rval = crypto_mv(ep, peer)) != XEVNT_OK) break; peer->crypto |= CRYPTO_FLAG_VRFY; peer->flash &= ~TEST8; snprintf(statstr, NTP_MAXSTRLEN, "mv %s fs %u", peer->issuer, ntohl(ep->fstamp)); record_crypto_stats(&peer->srcadr, statstr); #ifdef DEBUG if (debug) printf("crypto_recv: %s\n", statstr); #endif break; /* * Cookie response in client and symmetric modes. If the * cookie bit is set, the working cookie is the EXOR of * the current and new values. */ case CRYPTO_COOK | CRYPTO_RESP: /* * Discard the message if invalid or signature * not verified with respect to the cookie * values. */ if ((rval = crypto_verify(ep, &peer->cookval, peer)) != XEVNT_OK) break; /* * Decrypt the cookie, hunting all the time for * errors. */ if (vallen == (u_int)EVP_PKEY_size(host_pkey)) { if (RSA_private_decrypt(vallen, (u_char *)ep->pkt, (u_char *)&temp32, host_pkey->pkey.rsa, RSA_PKCS1_OAEP_PADDING) <= 0) { rval = XEVNT_CKY; break; } else { cookie = ntohl(temp32); } } else { rval = XEVNT_CKY; break; } /* * Install cookie values and light the cookie * bit. If this is not broadcast client mode, we * are done here. */ key_expire(peer); if (hismode == MODE_ACTIVE || hismode == MODE_PASSIVE) peer->pcookie = peer->hcookie ^ cookie; else peer->pcookie = cookie; peer->crypto |= CRYPTO_FLAG_COOK; peer->flash &= ~TEST8; snprintf(statstr, NTP_MAXSTRLEN, "cook %x ts %u fs %u", peer->pcookie, ntohl(ep->tstamp), ntohl(ep->fstamp)); record_crypto_stats(&peer->srcadr, statstr); #ifdef DEBUG if (debug) printf("crypto_recv: %s\n", statstr); #endif break; /* * Install autokey values in broadcast client and * symmetric modes. We have to do this every time the * sever/peer cookie changes or a new keylist is * rolled. Ordinarily, this is automatic as this message * is piggybacked on the first NTP packet sent upon * either of these events. Note that a broadcast client * or symmetric peer can receive this response without a * matching request. */ case CRYPTO_AUTO | CRYPTO_RESP: /* * Discard the message if invalid or signature * not verified with respect to the receive * autokey values. */ if ((rval = crypto_verify(ep, &peer->recval, peer)) != XEVNT_OK) break; /* * Discard the message if a broadcast client and * the association ID does not match. This might * happen if a broacast server restarts the * protocol. A protocol restart will occur at * the next ASSOC message. */ if ((peer->cast_flags & MDF_BCLNT) && peer->assoc != associd) break; /* * Install autokey values and light the * autokey bit. This is not hard. */ if (ep->tstamp == 0) break; if (peer->recval.ptr == NULL) peer->recval.ptr = emalloc(sizeof(struct autokey)); bp = (struct autokey *)peer->recval.ptr; peer->recval.tstamp = ep->tstamp; peer->recval.fstamp = ep->fstamp; ap = (struct autokey *)ep->pkt; bp->seq = ntohl(ap->seq); bp->key = ntohl(ap->key); peer->pkeyid = bp->key; peer->crypto |= CRYPTO_FLAG_AUTO; peer->flash &= ~TEST8; snprintf(statstr, NTP_MAXSTRLEN, "auto seq %d key %x ts %u fs %u", bp->seq, bp->key, ntohl(ep->tstamp), ntohl(ep->fstamp)); record_crypto_stats(&peer->srcadr, statstr); #ifdef DEBUG if (debug) printf("crypto_recv: %s\n", statstr); #endif break; /* * X509 certificate sign response. Validate the * certificate signed by the server and install. Later * this can be provided to clients of this server in * lieu of the self signed certificate in order to * validate the public key. */ case CRYPTO_SIGN | CRYPTO_RESP: /* * Discard the message if invalid. */ if ((rval = crypto_verify(ep, NULL, peer)) != XEVNT_OK) break; /* * Scan the certificate list to delete old * versions and link the newest version first on * the list. */ if ((xinfo = cert_install(ep, peer)) == NULL) { rval = XEVNT_CRT; break; } peer->crypto |= CRYPTO_FLAG_SIGN; peer->flash &= ~TEST8; temp32 = xinfo->nid; snprintf(statstr, NTP_MAXSTRLEN, "sign %s %s 0x%x %s (%u) fs %u", xinfo->subject, xinfo->issuer, xinfo->flags, OBJ_nid2ln(temp32), temp32, ntohl(ep->fstamp)); record_crypto_stats(&peer->srcadr, statstr); #ifdef DEBUG if (debug) printf("crypto_recv: %s\n", statstr); #endif break; /* * Install leapseconds values. While the leapsecond * values epoch, TAI offset and values expiration epoch * are retained, only the current TAI offset is provided * via the kernel to other applications. */ case CRYPTO_LEAP | CRYPTO_RESP: /* * Discard the message if invalid. We can't * compare the value timestamps here, as they * can be updated by different servers. */ if ((rval = crypto_verify(ep, NULL, peer)) != XEVNT_OK) break; /* * If the packet leap values are more recent * than the stored ones, install the new leap * values and recompute the signatures. */ if (ntohl(ep->pkt[2]) > leap_expire) { char tbuf[80], str1 [20], str2[20]; tai_leap.tstamp = ep->tstamp; tai_leap.fstamp = ep->fstamp; tai_leap.vallen = ep->vallen; leap_tai = ntohl(ep->pkt[0]); leap_sec = ntohl(ep->pkt[1]); leap_expire = ntohl(ep->pkt[2]); crypto_update(); strcpy(str1, fstostr(leap_sec)); strcpy(str2, fstostr(leap_expire)); snprintf(tbuf, sizeof(tbuf), "%d leap %s expire %s", leap_tai, str1, str2); report_event(EVNT_TAI, peer, tbuf); } peer->crypto |= CRYPTO_FLAG_LEAP; peer->flash &= ~TEST8; snprintf(statstr, NTP_MAXSTRLEN, "leap TAI offset %d at %u expire %u fs %u", ntohl(ep->pkt[0]), ntohl(ep->pkt[1]), ntohl(ep->pkt[2]), ntohl(ep->fstamp)); record_crypto_stats(&peer->srcadr, statstr); #ifdef DEBUG if (debug) printf("crypto_recv: %s\n", statstr); #endif break; /* * We come here in symmetric modes for miscellaneous * commands that have value fields but are processed on * the transmit side. All we need do here is check for * valid field length. Note that ASSOC is handled * separately. */ case CRYPTO_CERT: case CRYPTO_IFF: case CRYPTO_GQ: case CRYPTO_MV: case CRYPTO_COOK: case CRYPTO_SIGN: if (len < VALUE_LEN) { rval = XEVNT_LEN; break; } /* fall through */ /* * We come here in symmetric modes for requests * requiring a response (above plus AUTO and LEAP) and * for responses. If a request, save the extension field * for later; invalid requests will be caught on the * transmit side. If an error or invalid response, * declare a protocol error. */ default: if (code & (CRYPTO_RESP | CRYPTO_ERROR)) { rval = XEVNT_ERR; } else if (peer->cmmd == NULL) { fp = emalloc(len); memcpy(fp, ep, len); peer->cmmd = fp; } } /* * The first error found terminates the extension field * scan and we return the laundry to the caller. */ if (rval != XEVNT_OK) { snprintf(statstr, NTP_MAXSTRLEN, "%04x %d %02x %s", htonl(ep->opcode), associd, rval, eventstr(rval)); record_crypto_stats(&peer->srcadr, statstr); #ifdef DEBUG if (debug) printf("crypto_recv: %s\n", statstr); #endif return (rval); } authlen += (len + 3) / 4 * 4; } return (rval); } /* * crypto_xmit - construct extension fields * * This routine is called both when an association is configured and * when one is not. The only case where this matters is to retrieve the * autokey information, in which case the caller has to provide the * association ID to match the association. * * Side effect: update the packet offset. * * Errors * XEVNT_OK success * XEVNT_CRT bad or missing certificate * XEVNT_ERR protocol error * XEVNT_LEN bad field format or length * XEVNT_PER host certificate expired */ int crypto_xmit( struct peer *peer, /* peer structure pointer */ struct pkt *xpkt, /* transmit packet pointer */ struct recvbuf *rbufp, /* receive buffer pointer */ int start, /* offset to extension field */ struct exten *ep, /* extension pointer */ keyid_t cookie /* session cookie */ ) { struct exten *fp; /* extension pointers */ struct cert_info *cp, *xp, *yp; /* cert info/value pointer */ sockaddr_u *srcadr_sin; /* source address */ u_int32 *pkt; /* packet pointer */ u_int opcode; /* extension field opcode */ char certname[MAXHOSTNAME + 1]; /* subject name buffer */ char statstr[NTP_MAXSTRLEN]; /* statistics for filegen */ tstamp_t tstamp; u_int vallen; struct value vtemp; associd_t associd; int rval; int len; keyid_t tcookie; /* * Generate the requested extension field request code, length * and association ID. If this is a response and the host is not * synchronized, light the error bit and go home. */ pkt = (u_int32 *)xpkt + start / 4; fp = (struct exten *)pkt; opcode = ntohl(ep->opcode); if (peer != NULL) { srcadr_sin = &peer->srcadr; if (!(opcode & CRYPTO_RESP)) peer->opcode = ep->opcode; } else { srcadr_sin = &rbufp->recv_srcadr; } associd = (associd_t) ntohl(ep->associd); len = 8; fp->opcode = htonl((opcode & 0xffff0000) | len); fp->associd = ep->associd; rval = XEVNT_OK; tstamp = crypto_time(); switch (opcode & 0xffff0000) { /* * Send association request and response with status word and * host name. Note, this message is not signed and the filestamp * contains only the status word. */ case CRYPTO_ASSOC: case CRYPTO_ASSOC | CRYPTO_RESP: len = crypto_send(fp, &hostval, start); fp->fstamp = htonl(crypto_flags); break; /* * Send certificate request. Use the values from the extension * field. */ case CRYPTO_CERT: memset(&vtemp, 0, sizeof(vtemp)); vtemp.tstamp = ep->tstamp; vtemp.fstamp = ep->fstamp; vtemp.vallen = ep->vallen; vtemp.ptr = (u_char *)ep->pkt; len = crypto_send(fp, &vtemp, start); break; /* * Send sign request. Use the host certificate, which is self- * signed and may or may not be trusted. */ case CRYPTO_SIGN: if (tstamp < cert_host->first || tstamp > cert_host->last) rval = XEVNT_PER; else len = crypto_send(fp, &cert_host->cert, start); break; /* * Send certificate response. Use the name in the extension * field to find the certificate in the cache. If the request * contains no subject name, assume the name of this host. This * is for backwards compatibility. Private certificates are * never sent. * * There may be several certificates matching the request. First * choice is a self-signed trusted certificate; second choice is * any certificate signed by another host. There is no third * choice. */ case CRYPTO_CERT | CRYPTO_RESP: vallen = ntohl(ep->vallen); if (vallen == 0 || vallen > MAXHOSTNAME) { rval = XEVNT_LEN; break; } else { memcpy(certname, ep->pkt, vallen); certname[vallen] = '\0'; } /* * Find all public valid certificates with matching * subject. If a self-signed, trusted certificate is * found, use that certificate. If not, use the last non * self-signed certificate. */ xp = yp = NULL; for (cp = cinfo; cp != NULL; cp = cp->link) { if (cp->flags & (CERT_PRIV | CERT_ERROR)) continue; if (strcmp(certname, cp->subject) != 0) continue; if (strcmp(certname, cp->issuer) != 0) yp = cp; else if (cp ->flags & CERT_TRUST) xp = cp; continue; } /* * Be careful who you trust. If the certificate is not * found, return an empty response. Note that we dont * enforce lifetimes here. * * The timestamp and filestamp are taken from the * certificate value structure. For all certificates the * timestamp is the latest signature update time. For * host and imported certificates the filestamp is the * creation epoch. For signed certificates the filestamp * is the creation epoch of the trusted certificate at * the root of the certificate trail. In principle, this * allows strong checking for signature masquerade. */ if (xp == NULL) xp = yp; if (xp == NULL) break; if (tstamp == 0) break; len = crypto_send(fp, &xp->cert, start); break; /* * Send challenge in Schnorr (IFF) identity scheme. */ case CRYPTO_IFF: if (peer == NULL) break; /* hack attack */ if ((rval = crypto_alice(peer, &vtemp)) == XEVNT_OK) { len = crypto_send(fp, &vtemp, start); value_free(&vtemp); } break; /* * Send response in Schnorr (IFF) identity scheme. */ case CRYPTO_IFF | CRYPTO_RESP: if ((rval = crypto_bob(ep, &vtemp)) == XEVNT_OK) { len = crypto_send(fp, &vtemp, start); value_free(&vtemp); } break; /* * Send challenge in Guillou-Quisquater (GQ) identity scheme. */ case CRYPTO_GQ: if (peer == NULL) break; /* hack attack */ if ((rval = crypto_alice2(peer, &vtemp)) == XEVNT_OK) { len = crypto_send(fp, &vtemp, start); value_free(&vtemp); } break; /* * Send response in Guillou-Quisquater (GQ) identity scheme. */ case CRYPTO_GQ | CRYPTO_RESP: if ((rval = crypto_bob2(ep, &vtemp)) == XEVNT_OK) { len = crypto_send(fp, &vtemp, start); value_free(&vtemp); } break; /* * Send challenge in MV identity scheme. */ case CRYPTO_MV: if (peer == NULL) break; /* hack attack */ if ((rval = crypto_alice3(peer, &vtemp)) == XEVNT_OK) { len = crypto_send(fp, &vtemp, start); value_free(&vtemp); } break; /* * Send response in MV identity scheme. */ case CRYPTO_MV | CRYPTO_RESP: if ((rval = crypto_bob3(ep, &vtemp)) == XEVNT_OK) { len = crypto_send(fp, &vtemp, start); value_free(&vtemp); } break; /* * Send certificate sign response. The integrity of the request * certificate has already been verified on the receive side. * Sign the response using the local server key. Use the * filestamp from the request and use the timestamp as the * current time. Light the error bit if the certificate is * invalid or contains an unverified signature. */ case CRYPTO_SIGN | CRYPTO_RESP: if ((rval = cert_sign(ep, &vtemp)) == XEVNT_OK) { len = crypto_send(fp, &vtemp, start); value_free(&vtemp); } break; /* * Send public key and signature. Use the values from the public * key. */ case CRYPTO_COOK: len = crypto_send(fp, &pubkey, start); break; /* * Encrypt and send cookie and signature. Light the error bit if * anything goes wrong. */ case CRYPTO_COOK | CRYPTO_RESP: if ((opcode & 0xffff) < VALUE_LEN) { rval = XEVNT_LEN; break; } if (peer == NULL) tcookie = cookie; else tcookie = peer->hcookie; if ((rval = crypto_encrypt(ep, &vtemp, &tcookie)) == XEVNT_OK) { len = crypto_send(fp, &vtemp, start); value_free(&vtemp); } break; /* * Find peer and send autokey data and signature in broadcast * server and symmetric modes. Use the values in the autokey * structure. If no association is found, either the server has * restarted with new associations or some perp has replayed an * old message, in which case light the error bit. */ case CRYPTO_AUTO | CRYPTO_RESP: if (peer == NULL) { if ((peer = findpeerbyassoc(associd)) == NULL) { rval = XEVNT_ERR; break; } } peer->flags &= ~FLAG_ASSOC; len = crypto_send(fp, &peer->sndval, start); break; /* * Send leapseconds values and signature. Use the values from * the tai structure. If no table has been loaded, just send an * empty request. */ case CRYPTO_LEAP | CRYPTO_RESP: len = crypto_send(fp, &tai_leap, start); break; /* * Default - Send a valid command for unknown requests; send * an error response for unknown resonses. */ default: if (opcode & CRYPTO_RESP) rval = XEVNT_ERR; } /* * In case of error, flame the log. If a request, toss the * puppy; if a response, return so the sender can flame, too. */ if (rval != XEVNT_OK) { u_int32 uint32; uint32 = CRYPTO_ERROR; opcode |= uint32; fp->opcode |= htonl(uint32); snprintf(statstr, NTP_MAXSTRLEN, "%04x %d %02x %s", opcode, associd, rval, eventstr(rval)); record_crypto_stats(srcadr_sin, statstr); #ifdef DEBUG if (debug) printf("crypto_xmit: %s\n", statstr); #endif if (!(opcode & CRYPTO_RESP)) return (0); } #ifdef DEBUG if (debug) printf( "crypto_xmit: flags 0x%x offset %d len %d code 0x%x associd %d\n", crypto_flags, start, len, opcode >> 16, associd); #endif return (len); } /* * crypto_verify - verify the extension field value and signature * * Returns * XEVNT_OK success * XEVNT_ERR protocol error * XEVNT_FSP bad filestamp * XEVNT_LEN bad field format or length * XEVNT_PUB bad or missing public key * XEVNT_SGL bad signature length * XEVNT_SIG signature not verified * XEVNT_TSP bad timestamp */ static int crypto_verify( struct exten *ep, /* extension pointer */ struct value *vp, /* value pointer */ struct peer *peer /* peer structure pointer */ ) { EVP_PKEY *pkey; /* server public key */ EVP_MD_CTX ctx; /* signature context */ tstamp_t tstamp, tstamp1 = 0; /* timestamp */ tstamp_t fstamp, fstamp1 = 0; /* filestamp */ u_int vallen; /* value length */ u_int siglen; /* signature length */ u_int opcode, len; int i; /* * We are extremely parannoyed. We require valid opcode, length, * association ID, timestamp, filestamp, public key, digest, * signature length and signature, where relevant. Note that * preliminary length checks are done in the main loop. */ len = ntohl(ep->opcode) & 0x0000ffff; opcode = ntohl(ep->opcode) & 0xffff0000; /* * Check for valid value header, association ID and extension * field length. Remember, it is not an error to receive an * unsolicited response; however, the response ID must match * the association ID. */ if (opcode & CRYPTO_ERROR) return (XEVNT_ERR); if (len < VALUE_LEN) return (XEVNT_LEN); if (opcode == (CRYPTO_AUTO | CRYPTO_RESP) && (peer->pmode == MODE_BROADCAST || (peer->cast_flags & MDF_BCLNT))) { if (ntohl(ep->associd) != peer->assoc) return (XEVNT_ERR); } else { if (ntohl(ep->associd) != peer->associd) return (XEVNT_ERR); } /* * We have a valid value header. Check for valid value and * signature field lengths. The extension field length must be * long enough to contain the value header, value and signature. * Note both the value and signature field lengths are rounded * up to the next word (4 octets). */ vallen = ntohl(ep->vallen); if (vallen == 0) return (XEVNT_LEN); i = (vallen + 3) / 4; siglen = ntohl(ep->pkt[i++]); if (len < VALUE_LEN + ((vallen + 3) / 4) * 4 + ((siglen + 3) / 4) * 4) return (XEVNT_LEN); /* * Check for valid timestamp and filestamp. If the timestamp is * zero, the sender is not synchronized and signatures are * not possible. If nonzero the timestamp must not precede the * filestamp. The timestamp and filestamp must not precede the * corresponding values in the value structure, if present. */ tstamp = ntohl(ep->tstamp); fstamp = ntohl(ep->fstamp); if (tstamp == 0) return (XEVNT_TSP); if (tstamp < fstamp) return (XEVNT_TSP); if (vp != NULL) { tstamp1 = ntohl(vp->tstamp); fstamp1 = ntohl(vp->fstamp); if (tstamp1 != 0 && fstamp1 != 0) { if (tstamp < tstamp1) return (XEVNT_TSP); if ((tstamp < fstamp1 || fstamp < fstamp1)) return (XEVNT_FSP); } } /* * At the time the certificate message is validated, the public * key in the message is not available. Thus, don't try to * verify the signature. */ if (opcode == (CRYPTO_CERT | CRYPTO_RESP)) return (XEVNT_OK); /* * Check for valid signature length, public key and digest * algorithm. */ if (crypto_flags & peer->crypto & CRYPTO_FLAG_PRIV) pkey = sign_pkey; else pkey = peer->pkey; if (siglen == 0 || pkey == NULL || peer->digest == NULL) return (XEVNT_ERR); if (siglen != (u_int)EVP_PKEY_size(pkey)) return (XEVNT_SGL); /* * Darn, I thought we would never get here. Verify the * signature. If the identity exchange is verified, light the * proventic bit. What a relief. */ EVP_VerifyInit(&ctx, peer->digest); EVP_VerifyUpdate(&ctx, (u_char *)&ep->tstamp, vallen + 12); if (EVP_VerifyFinal(&ctx, (u_char *)&ep->pkt[i], siglen, pkey) <= 0) return (XEVNT_SIG); if (peer->crypto & CRYPTO_FLAG_VRFY) peer->crypto |= CRYPTO_FLAG_PROV; return (XEVNT_OK); } /* * crypto_encrypt - construct encrypted cookie and signature from * extension field and cookie * * Returns * XEVNT_OK success * XEVNT_CKY bad or missing cookie * XEVNT_PUB bad or missing public key */ static int crypto_encrypt( struct exten *ep, /* extension pointer */ struct value *vp, /* value pointer */ keyid_t *cookie /* server cookie */ ) { EVP_PKEY *pkey; /* public key */ EVP_MD_CTX ctx; /* signature context */ tstamp_t tstamp; /* NTP timestamp */ u_int32 temp32; u_int len; u_char *ptr; /* * Extract the public key from the request. */ len = ntohl(ep->vallen); ptr = (u_char *)ep->pkt; pkey = d2i_PublicKey(EVP_PKEY_RSA, NULL, &ptr, len); if (pkey == NULL) { msyslog(LOG_ERR, "crypto_encrypt: %s", ERR_error_string(ERR_get_error(), NULL)); return (XEVNT_PUB); } /* * Encrypt the cookie, encode in ASN.1 and sign. */ memset(vp, 0, sizeof(struct value)); tstamp = crypto_time(); vp->tstamp = htonl(tstamp); vp->fstamp = hostval.tstamp; len = EVP_PKEY_size(pkey); vp->vallen = htonl(len); vp->ptr = emalloc(len); ptr = vp->ptr; temp32 = htonl(*cookie); if (RSA_public_encrypt(4, (u_char *)&temp32, ptr, pkey->pkey.rsa, RSA_PKCS1_OAEP_PADDING) <= 0) { msyslog(LOG_ERR, "crypto_encrypt: %s", ERR_error_string(ERR_get_error(), NULL)); free(vp->ptr); EVP_PKEY_free(pkey); return (XEVNT_CKY); } EVP_PKEY_free(pkey); if (tstamp == 0) return (XEVNT_OK); vp->sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)&vp->tstamp, 12); EVP_SignUpdate(&ctx, vp->ptr, len); if (EVP_SignFinal(&ctx, vp->sig, &len, sign_pkey)) vp->siglen = htonl(sign_siglen); return (XEVNT_OK); } /* * crypto_ident - construct extension field for identity scheme * * This routine determines which identity scheme is in use and * constructs an extension field for that scheme. * * Returns * CRYTPO_IFF IFF scheme * CRYPTO_GQ GQ scheme * CRYPTO_MV MV scheme * CRYPTO_NULL no available scheme */ u_int crypto_ident( struct peer *peer /* peer structure pointer */ ) { char filename[MAXFILENAME]; /* * We come here after the group trusted host has been found; its * name defines the group name. Search the key cache for all * keys matching the same group name in order IFF, GQ and MV. * Use the first one available. */ if (peer->crypto & CRYPTO_FLAG_IFF) { snprintf(filename, MAXFILENAME, "ntpkey_iffpar_%s", peer->issuer); peer->ident_pkey = crypto_key(filename, NULL, &peer->srcadr); if (peer->ident_pkey != NULL) return (CRYPTO_IFF); } if (peer->crypto & CRYPTO_FLAG_GQ) { snprintf(filename, MAXFILENAME, "ntpkey_gqpar_%s", peer->issuer); peer->ident_pkey = crypto_key(filename, NULL, &peer->srcadr); if (peer->ident_pkey != NULL) return (CRYPTO_GQ); } if (peer->crypto & CRYPTO_FLAG_MV) { snprintf(filename, MAXFILENAME, "ntpkey_mvpar_%s", peer->issuer); peer->ident_pkey = crypto_key(filename, NULL, &peer->srcadr); if (peer->ident_pkey != NULL) return (CRYPTO_MV); } msyslog(LOG_NOTICE, "crypto_ident: no identity parameters found for group %s", peer->issuer); return (CRYPTO_NULL); } /* * crypto_args - construct extension field from arguments * * This routine creates an extension field with current timestamps and * specified opcode, association ID and optional string. Note that the * extension field is created here, but freed after the crypto_xmit() * call in the protocol module. * * Returns extension field pointer (no errors) */ struct exten * crypto_args( struct peer *peer, /* peer structure pointer */ u_int opcode, /* operation code */ associd_t associd, /* association ID */ char *str /* argument string */ ) { tstamp_t tstamp; /* NTP timestamp */ struct exten *ep; /* extension field pointer */ u_int len; /* extension field length */ tstamp = crypto_time(); len = sizeof(struct exten); if (str != NULL) len += strlen(str); ep = emalloc(len); memset(ep, 0, len); if (opcode == 0) return (ep); ep->opcode = htonl(opcode + len); ep->associd = htonl(associd); ep->tstamp = htonl(tstamp); ep->fstamp = hostval.tstamp; ep->vallen = 0; if (str != NULL) { ep->vallen = htonl(strlen(str)); memcpy((char *)ep->pkt, str, strlen(str)); } return (ep); } /* * crypto_send - construct extension field from value components * * The value and signature fields are zero-padded to a word boundary. * Note: it is not polite to send a nonempty signature with zero * timestamp or a nonzero timestamp with an empty signature, but those * rules are not enforced here. */ int crypto_send( struct exten *ep, /* extension field pointer */ struct value *vp, /* value pointer */ int start /* buffer offset */ ) { u_int len, vallen, siglen, opcode; int i, j; /* * Calculate extension field length and check for buffer * overflow. Leave room for the MAC. */ len = 16; vallen = ntohl(vp->vallen); len += ((vallen + 3) / 4 + 1) * 4; siglen = ntohl(vp->siglen); len += ((siglen + 3) / 4 + 1) * 4; if (start + len > sizeof(struct pkt) - MAX_MAC_LEN) return (0); /* * Copy timestamps. */ ep->tstamp = vp->tstamp; ep->fstamp = vp->fstamp; ep->vallen = vp->vallen; /* * Copy value. If the data field is empty or zero length, * encode an empty value with length zero. */ i = 0; if (vallen > 0 && vp->ptr != NULL) { j = vallen / 4; if (j * 4 < vallen) ep->pkt[i + j++] = 0; memcpy(&ep->pkt[i], vp->ptr, vallen); i += j; } /* * Copy signature. If the signature field is empty or zero * length, encode an empty signature with length zero. */ ep->pkt[i++] = vp->siglen; if (siglen > 0 && vp->sig != NULL) { j = vallen / 4; if (j * 4 < siglen) ep->pkt[i + j++] = 0; memcpy(&ep->pkt[i], vp->sig, siglen); i += j; } opcode = ntohl(ep->opcode); ep->opcode = htonl((opcode & 0xffff0000) | len); return (len); } /* * crypto_update - compute new public value and sign extension fields * * This routine runs periodically, like once a day, and when something * changes. It updates the timestamps on three value structures and one * value structure list, then signs all the structures: * * hostval host name (not signed) * pubkey public key * cinfo certificate info/value list * tai_leap leap values * * Filestamps are proventic data, so this routine runs only when the * host is synchronized to a proventicated source. Thus, the timestamp * is proventic and can be used to deflect clogging attacks. * * Returns void (no errors) */ void crypto_update(void) { EVP_MD_CTX ctx; /* message digest context */ struct cert_info *cp; /* certificate info/value */ char statstr[NTP_MAXSTRLEN]; /* statistics for filegen */ u_int32 *ptr; u_int len; hostval.tstamp = htonl(crypto_time()); if (hostval.tstamp == 0) return; /* * Sign public key and timestamps. The filestamp is derived from * the host key file extension from wherever the file was * generated. */ if (pubkey.vallen != 0) { pubkey.tstamp = hostval.tstamp; pubkey.siglen = 0; if (pubkey.sig == NULL) pubkey.sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)&pubkey, 12); EVP_SignUpdate(&ctx, pubkey.ptr, ntohl(pubkey.vallen)); if (EVP_SignFinal(&ctx, pubkey.sig, &len, sign_pkey)) pubkey.siglen = htonl(sign_siglen); } /* * Sign certificates and timestamps. The filestamp is derived * from the certificate file extension from wherever the file * was generated. Note we do not throw expired certificates * away; they may have signed younger ones. */ for (cp = cinfo; cp != NULL; cp = cp->link) { cp->cert.tstamp = hostval.tstamp; cp->cert.siglen = 0; if (cp->cert.sig == NULL) cp->cert.sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)&cp->cert, 12); EVP_SignUpdate(&ctx, cp->cert.ptr, ntohl(cp->cert.vallen)); if (EVP_SignFinal(&ctx, cp->cert.sig, &len, sign_pkey)) cp->cert.siglen = htonl(sign_siglen); } /* * Sign leapseconds values and timestamps. Note it is not an * error to return null values. */ tai_leap.tstamp = hostval.tstamp; tai_leap.fstamp = hostval.fstamp; len = 3 * sizeof(u_int32); if (tai_leap.ptr == NULL) tai_leap.ptr = emalloc(len); tai_leap.vallen = htonl(len); ptr = (u_int32 *)tai_leap.ptr; ptr[0] = htonl(leap_tai); ptr[1] = htonl(leap_sec); ptr[2] = htonl(leap_expire); if (tai_leap.sig == NULL) tai_leap.sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)&tai_leap, 12); EVP_SignUpdate(&ctx, tai_leap.ptr, len); if (EVP_SignFinal(&ctx, tai_leap.sig, &len, sign_pkey)) tai_leap.siglen = htonl(sign_siglen); if (leap_sec > 0) crypto_flags |= CRYPTO_FLAG_TAI; snprintf(statstr, NTP_MAXSTRLEN, "signature update ts %u", ntohl(hostval.tstamp)); record_crypto_stats(NULL, statstr); #ifdef DEBUG if (debug) printf("crypto_update: %s\n", statstr); #endif } /* * value_free - free value structure components. * * Returns void (no errors) */ void value_free( struct value *vp /* value structure */ ) { if (vp->ptr != NULL) free(vp->ptr); if (vp->sig != NULL) free(vp->sig); memset(vp, 0, sizeof(struct value)); } /* * crypto_time - returns current NTP time. * * Returns NTP seconds if in synch, 0 otherwise */ tstamp_t crypto_time() { l_fp tstamp; /* NTP time */ L_CLR(&tstamp); if (sys_leap != LEAP_NOTINSYNC) get_systime(&tstamp); return (tstamp.l_ui); } /* * asn2ntp - convert ASN1_TIME time structure to NTP time. * * Returns NTP seconds (no errors) */ u_long asn2ntp ( ASN1_TIME *asn1time /* pointer to ASN1_TIME structure */ ) { char *v; /* pointer to ASN1_TIME string */ struct tm tm; /* used to convert to NTP time */ /* * Extract time string YYMMDDHHMMSSZ from ASN1 time structure. * Note that the YY, MM, DD fields start with one, the HH, MM, * SS fiels start with zero and the Z character is ignored. * Also note that years less than 50 map to years greater than * 100. Dontcha love ASN.1? Better than MIL-188. */ v = (char *)asn1time->data; tm.tm_year = (v[0] - '0') * 10 + v[1] - '0'; if (tm.tm_year < 50) tm.tm_year += 100; tm.tm_mon = (v[2] - '0') * 10 + v[3] - '0' - 1; tm.tm_mday = (v[4] - '0') * 10 + v[5] - '0'; tm.tm_hour = (v[6] - '0') * 10 + v[7] - '0'; tm.tm_min = (v[8] - '0') * 10 + v[9] - '0'; tm.tm_sec = (v[10] - '0') * 10 + v[11] - '0'; tm.tm_wday = 0; tm.tm_yday = 0; tm.tm_isdst = 0; return ((u_long)timegm(&tm) + JAN_1970); } /* * bigdig() - compute a BIGNUM MD5 hash of a BIGNUM number. * * Returns void (no errors) */ static void bighash( BIGNUM *bn, /* BIGNUM * from */ BIGNUM *bk /* BIGNUM * to */ ) { EVP_MD_CTX ctx; /* message digest context */ u_char dgst[EVP_MAX_MD_SIZE]; /* message digest */ u_char *ptr; /* a BIGNUM as binary string */ u_int len; len = BN_num_bytes(bn); ptr = emalloc(len); BN_bn2bin(bn, ptr); EVP_DigestInit(&ctx, EVP_md5()); EVP_DigestUpdate(&ctx, ptr, len); EVP_DigestFinal(&ctx, dgst, &len); BN_bin2bn(dgst, len, bk); free(ptr); } /* *********************************************************************** * * * The following routines implement the Schnorr (IFF) identity scheme * * * *********************************************************************** * * The Schnorr (IFF) identity scheme is intended for use when * certificates are generated by some other trusted certificate * authority and the certificate cannot be used to convey public * parameters. There are two kinds of files: encrypted server files that * contain private and public values and nonencrypted client files that * contain only public values. New generations of server files must be * securely transmitted to all servers of the group; client files can be * distributed by any means. The scheme is self contained and * independent of new generations of host keys, sign keys and * certificates. * * The IFF values hide in a DSA cuckoo structure which uses the same * parameters. The values are used by an identity scheme based on DSA * cryptography and described in Stimson p. 285. The p is a 512-bit * prime, g a generator of Zp* and q a 160-bit prime that divides p - 1 * and is a qth root of 1 mod p; that is, g^q = 1 mod p. The TA rolls a * private random group key b (0 < b < q) and public key v = g^b, then * sends (p, q, g, b) to the servers and (p, q, g, v) to the clients. * Alice challenges Bob to confirm identity using the protocol described * below. * * How it works * * The scheme goes like this. Both Alice and Bob have the public primes * p, q and generator g. The TA gives private key b to Bob and public * key v to Alice. * * Alice rolls new random challenge r (o < r < q) and sends to Bob in * the IFF request message. Bob rolls new random k (0 < k < q), then * computes y = k + b r mod q and x = g^k mod p and sends (y, hash(x)) * to Alice in the response message. Besides making the response * shorter, the hash makes it effectivey impossible for an intruder to * solve for b by observing a number of these messages. * * Alice receives the response and computes g^y v^r mod p. After a bit * of algebra, this simplifies to g^k. If the hash of this result * matches hash(x), Alice knows that Bob has the group key b. The signed * response binds this knowledge to Bob's private key and the public key * previously received in his certificate. * * crypto_alice - construct Alice's challenge in IFF scheme * * Returns * XEVNT_OK success * XEVNT_ID bad or missing group key * XEVNT_PUB bad or missing public key */ static int crypto_alice( struct peer *peer, /* peer pointer */ struct value *vp /* value pointer */ ) { DSA *dsa; /* IFF parameters */ BN_CTX *bctx; /* BIGNUM context */ EVP_MD_CTX ctx; /* signature context */ tstamp_t tstamp; u_int len; /* * The identity parameters must have correct format and content. */ if (peer->ident_pkey == NULL) return (XEVNT_ID); if ((dsa = peer->ident_pkey->pkey->pkey.dsa) == NULL) { msyslog(LOG_NOTICE, "crypto_alice: defective key"); return (XEVNT_PUB); } /* * Roll new random r (0 < r < q). */ if (peer->iffval != NULL) BN_free(peer->iffval); peer->iffval = BN_new(); len = BN_num_bytes(dsa->q); BN_rand(peer->iffval, len * 8, -1, 1); /* r mod q*/ bctx = BN_CTX_new(); BN_mod(peer->iffval, peer->iffval, dsa->q, bctx); BN_CTX_free(bctx); /* * Sign and send to Bob. The filestamp is from the local file. */ memset(vp, 0, sizeof(struct value)); tstamp = crypto_time(); vp->tstamp = htonl(tstamp); vp->fstamp = htonl(peer->ident_pkey->fstamp); vp->vallen = htonl(len); vp->ptr = emalloc(len); BN_bn2bin(peer->iffval, vp->ptr); if (tstamp == 0) return (XEVNT_OK); vp->sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)&vp->tstamp, 12); EVP_SignUpdate(&ctx, vp->ptr, len); if (EVP_SignFinal(&ctx, vp->sig, &len, sign_pkey)) vp->siglen = htonl(sign_siglen); return (XEVNT_OK); } /* * crypto_bob - construct Bob's response to Alice's challenge * * Returns * XEVNT_OK success * XEVNT_ERR protocol error * XEVNT_ID bad or missing group key */ static int crypto_bob( struct exten *ep, /* extension pointer */ struct value *vp /* value pointer */ ) { DSA *dsa; /* IFF parameters */ DSA_SIG *sdsa; /* DSA signature context fake */ BN_CTX *bctx; /* BIGNUM context */ EVP_MD_CTX ctx; /* signature context */ tstamp_t tstamp; /* NTP timestamp */ BIGNUM *bn, *bk, *r; u_char *ptr; u_int len; /* * If the IFF parameters are not valid, something awful * happened or we are being tormented. */ if (iffkey_info == NULL) { msyslog(LOG_NOTICE, "crypto_bob: scheme unavailable"); return (XEVNT_ID); } dsa = iffkey_info->pkey->pkey.dsa; /* * Extract r from the challenge. */ len = ntohl(ep->vallen); if ((r = BN_bin2bn((u_char *)ep->pkt, len, NULL)) == NULL) { msyslog(LOG_ERR, "crypto_bob: %s", ERR_error_string(ERR_get_error(), NULL)); return (XEVNT_ERR); } /* * Bob rolls random k (0 < k < q), computes y = k + b r mod q * and x = g^k mod p, then sends (y, hash(x)) to Alice. */ bctx = BN_CTX_new(); bk = BN_new(); bn = BN_new(); sdsa = DSA_SIG_new(); BN_rand(bk, len * 8, -1, 1); /* k */ BN_mod_mul(bn, dsa->priv_key, r, dsa->q, bctx); /* b r mod q */ BN_add(bn, bn, bk); BN_mod(bn, bn, dsa->q, bctx); /* k + b r mod q */ sdsa->r = BN_dup(bn); BN_mod_exp(bk, dsa->g, bk, dsa->p, bctx); /* g^k mod p */ bighash(bk, bk); sdsa->s = BN_dup(bk); BN_CTX_free(bctx); BN_free(r); BN_free(bn); BN_free(bk); #ifdef DEBUG if (debug > 1) DSA_print_fp(stdout, dsa, 0); #endif /* * Encode the values in ASN.1 and sign. The filestamp is from * the local file. */ len = i2d_DSA_SIG(sdsa, NULL); if (len == 0) { msyslog(LOG_ERR, "crypto_bob: %s", ERR_error_string(ERR_get_error(), NULL)); DSA_SIG_free(sdsa); return (XEVNT_ERR); } memset(vp, 0, sizeof(struct value)); tstamp = crypto_time(); vp->tstamp = htonl(tstamp); vp->fstamp = htonl(iffkey_info->fstamp); vp->vallen = htonl(len); ptr = emalloc(len); vp->ptr = ptr; i2d_DSA_SIG(sdsa, &ptr); DSA_SIG_free(sdsa); if (tstamp == 0) return (XEVNT_OK); vp->sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)&vp->tstamp, 12); EVP_SignUpdate(&ctx, vp->ptr, len); if (EVP_SignFinal(&ctx, vp->sig, &len, sign_pkey)) vp->siglen = htonl(sign_siglen); return (XEVNT_OK); } /* * crypto_iff - verify Bob's response to Alice's challenge * * Returns * XEVNT_OK success * XEVNT_FSP bad filestamp * XEVNT_ID bad or missing group key * XEVNT_PUB bad or missing public key */ int crypto_iff( struct exten *ep, /* extension pointer */ struct peer *peer /* peer structure pointer */ ) { DSA *dsa; /* IFF parameters */ BN_CTX *bctx; /* BIGNUM context */ DSA_SIG *sdsa; /* DSA parameters */ BIGNUM *bn, *bk; u_int len; const u_char *ptr; int temp; /* * If the IFF parameters are not valid or no challenge was sent, * something awful happened or we are being tormented. */ if (peer->ident_pkey == NULL) { msyslog(LOG_NOTICE, "crypto_iff: scheme unavailable"); return (XEVNT_ID); } if (ntohl(ep->fstamp) != peer->ident_pkey->fstamp) { msyslog(LOG_NOTICE, "crypto_iff: invalid filestamp %u", ntohl(ep->fstamp)); return (XEVNT_FSP); } if ((dsa = peer->ident_pkey->pkey->pkey.dsa) == NULL) { msyslog(LOG_NOTICE, "crypto_iff: defective key"); return (XEVNT_PUB); } if (peer->iffval == NULL) { msyslog(LOG_NOTICE, "crypto_iff: missing challenge"); return (XEVNT_ID); } /* * Extract the k + b r and g^k values from the response. */ bctx = BN_CTX_new(); bk = BN_new(); bn = BN_new(); len = ntohl(ep->vallen); ptr = (u_char *)ep->pkt; if ((sdsa = d2i_DSA_SIG(NULL, &ptr, len)) == NULL) { BN_free(bn); BN_free(bk); BN_CTX_free(bctx); msyslog(LOG_ERR, "crypto_iff: %s", ERR_error_string(ERR_get_error(), NULL)); return (XEVNT_ERR); } /* * Compute g^(k + b r) g^(q - b)r mod p. */ BN_mod_exp(bn, dsa->pub_key, peer->iffval, dsa->p, bctx); BN_mod_exp(bk, dsa->g, sdsa->r, dsa->p, bctx); BN_mod_mul(bn, bn, bk, dsa->p, bctx); /* * Verify the hash of the result matches hash(x). */ bighash(bn, bn); temp = BN_cmp(bn, sdsa->s); BN_free(bn); BN_free(bk); BN_CTX_free(bctx); BN_free(peer->iffval); peer->iffval = NULL; DSA_SIG_free(sdsa); if (temp == 0) return (XEVNT_OK); msyslog(LOG_NOTICE, "crypto_iff: identity not verified"); return (XEVNT_ID); } /* *********************************************************************** * * * The following routines implement the Guillou-Quisquater (GQ) * * identity scheme * * * *********************************************************************** * * The Guillou-Quisquater (GQ) identity scheme is intended for use when * the certificate can be used to convey public parameters. The scheme * uses a X509v3 certificate extension field do convey the public key of * a private key known only to servers. There are two kinds of files: * encrypted server files that contain private and public values and * nonencrypted client files that contain only public values. New * generations of server files must be securely transmitted to all * servers of the group; client files can be distributed by any means. * The scheme is self contained and independent of new generations of * host keys and sign keys. The scheme is self contained and independent * of new generations of host keys and sign keys. * * The GQ parameters hide in a RSA cuckoo structure which uses the same * parameters. The values are used by an identity scheme based on RSA * cryptography and described in Stimson p. 300 (with errors). The 512- * bit public modulus is n = p q, where p and q are secret large primes. * The TA rolls private random group key b as RSA exponent. These values * are known to all group members. * * When rolling new certificates, a server recomputes the private and * public keys. The private key u is a random roll, while the public key * is the inverse obscured by the group key v = (u^-1)^b. These values * replace the private and public keys normally generated by the RSA * scheme. Alice challenges Bob to confirm identity using the protocol * described below. * * How it works * * The scheme goes like this. Both Alice and Bob have the same modulus n * and some random b as the group key. These values are computed and * distributed in advance via secret means, although only the group key * b is truly secret. Each has a private random private key u and public * key (u^-1)^b, although not necessarily the same ones. Bob and Alice * can regenerate the key pair from time to time without affecting * operations. The public key is conveyed on the certificate in an * extension field; the private key is never revealed. * * Alice rolls new random challenge r and sends to Bob in the GQ * request message. Bob rolls new random k, then computes y = k u^r mod * n and x = k^b mod n and sends (y, hash(x)) to Alice in the response * message. Besides making the response shorter, the hash makes it * effectivey impossible for an intruder to solve for b by observing * a number of these messages. * * Alice receives the response and computes y^b v^r mod n. After a bit * of algebra, this simplifies to k^b. If the hash of this result * matches hash(x), Alice knows that Bob has the group key b. The signed * response binds this knowledge to Bob's private key and the public key * previously received in his certificate. * * crypto_alice2 - construct Alice's challenge in GQ scheme * * Returns * XEVNT_OK success * XEVNT_ID bad or missing group key * XEVNT_PUB bad or missing public key */ static int crypto_alice2( struct peer *peer, /* peer pointer */ struct value *vp /* value pointer */ ) { RSA *rsa; /* GQ parameters */ BN_CTX *bctx; /* BIGNUM context */ EVP_MD_CTX ctx; /* signature context */ tstamp_t tstamp; u_int len; /* * The identity parameters must have correct format and content. */ if (peer->ident_pkey == NULL) return (XEVNT_ID); if ((rsa = peer->ident_pkey->pkey->pkey.rsa) == NULL) { msyslog(LOG_NOTICE, "crypto_alice2: defective key"); return (XEVNT_PUB); } /* * Roll new random r (0 < r < n). */ if (peer->iffval != NULL) BN_free(peer->iffval); peer->iffval = BN_new(); len = BN_num_bytes(rsa->n); BN_rand(peer->iffval, len * 8, -1, 1); /* r mod n */ bctx = BN_CTX_new(); BN_mod(peer->iffval, peer->iffval, rsa->n, bctx); BN_CTX_free(bctx); /* * Sign and send to Bob. The filestamp is from the local file. */ memset(vp, 0, sizeof(struct value)); tstamp = crypto_time(); vp->tstamp = htonl(tstamp); vp->fstamp = htonl(peer->ident_pkey->fstamp); vp->vallen = htonl(len); vp->ptr = emalloc(len); BN_bn2bin(peer->iffval, vp->ptr); if (tstamp == 0) return (XEVNT_OK); vp->sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)&vp->tstamp, 12); EVP_SignUpdate(&ctx, vp->ptr, len); if (EVP_SignFinal(&ctx, vp->sig, &len, sign_pkey)) vp->siglen = htonl(sign_siglen); return (XEVNT_OK); } /* * crypto_bob2 - construct Bob's response to Alice's challenge * * Returns * XEVNT_OK success * XEVNT_ERR protocol error * XEVNT_ID bad or missing group key */ static int crypto_bob2( struct exten *ep, /* extension pointer */ struct value *vp /* value pointer */ ) { RSA *rsa; /* GQ parameters */ DSA_SIG *sdsa; /* DSA parameters */ BN_CTX *bctx; /* BIGNUM context */ EVP_MD_CTX ctx; /* signature context */ tstamp_t tstamp; /* NTP timestamp */ BIGNUM *r, *k, *g, *y; u_char *ptr; u_int len; /* * If the GQ parameters are not valid, something awful * happened or we are being tormented. */ if (gqkey_info == NULL) { msyslog(LOG_NOTICE, "crypto_bob2: scheme unavailable"); return (XEVNT_ID); } rsa = gqkey_info->pkey->pkey.rsa; /* * Extract r from the challenge. */ len = ntohl(ep->vallen); if ((r = BN_bin2bn((u_char *)ep->pkt, len, NULL)) == NULL) { msyslog(LOG_ERR, "crypto_bob2: %s", ERR_error_string(ERR_get_error(), NULL)); return (XEVNT_ERR); } /* * Bob rolls random k (0 < k < n), computes y = k u^r mod n and * x = k^b mod n, then sends (y, hash(x)) to Alice. */ bctx = BN_CTX_new(); k = BN_new(); g = BN_new(); y = BN_new(); sdsa = DSA_SIG_new(); BN_rand(k, len * 8, -1, 1); /* k */ BN_mod(k, k, rsa->n, bctx); BN_mod_exp(y, rsa->p, r, rsa->n, bctx); /* u^r mod n */ BN_mod_mul(y, k, y, rsa->n, bctx); /* k u^r mod n */ sdsa->r = BN_dup(y); BN_mod_exp(g, k, rsa->e, rsa->n, bctx); /* k^b mod n */ bighash(g, g); sdsa->s = BN_dup(g); BN_CTX_free(bctx); BN_free(r); BN_free(k); BN_free(g); BN_free(y); #ifdef DEBUG if (debug > 1) RSA_print_fp(stdout, rsa, 0); #endif /* * Encode the values in ASN.1 and sign. The filestamp is from * the local file. */ len = i2d_DSA_SIG(sdsa, NULL); if (len <= 0) { msyslog(LOG_ERR, "crypto_bob2: %s", ERR_error_string(ERR_get_error(), NULL)); DSA_SIG_free(sdsa); return (XEVNT_ERR); } memset(vp, 0, sizeof(struct value)); tstamp = crypto_time(); vp->tstamp = htonl(tstamp); vp->fstamp = htonl(gqkey_info->fstamp); vp->vallen = htonl(len); ptr = emalloc(len); vp->ptr = ptr; i2d_DSA_SIG(sdsa, &ptr); DSA_SIG_free(sdsa); if (tstamp == 0) return (XEVNT_OK); vp->sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)&vp->tstamp, 12); EVP_SignUpdate(&ctx, vp->ptr, len); if (EVP_SignFinal(&ctx, vp->sig, &len, sign_pkey)) vp->siglen = htonl(sign_siglen); return (XEVNT_OK); } /* * crypto_gq - verify Bob's response to Alice's challenge * * Returns * XEVNT_OK success * XEVNT_ERR protocol error * XEVNT_FSP bad filestamp * XEVNT_ID bad or missing group keys * XEVNT_PUB bad or missing public key */ int crypto_gq( struct exten *ep, /* extension pointer */ struct peer *peer /* peer structure pointer */ ) { RSA *rsa; /* GQ parameters */ BN_CTX *bctx; /* BIGNUM context */ DSA_SIG *sdsa; /* RSA signature context fake */ BIGNUM *y, *v; const u_char *ptr; long len; u_int temp; /* * If the GQ parameters are not valid or no challenge was sent, * something awful happened or we are being tormented. Note that * the filestamp on the local key file can be greater than on * the remote parameter file if the keys have been refreshed. */ if (peer->ident_pkey == NULL) { msyslog(LOG_NOTICE, "crypto_gq: scheme unavailable"); return (XEVNT_ID); } if (ntohl(ep->fstamp) < peer->ident_pkey->fstamp) { msyslog(LOG_NOTICE, "crypto_gq: invalid filestamp %u", ntohl(ep->fstamp)); return (XEVNT_FSP); } if ((rsa = peer->ident_pkey->pkey->pkey.rsa) == NULL) { msyslog(LOG_NOTICE, "crypto_gq: defective key"); return (XEVNT_PUB); } if (peer->iffval == NULL) { msyslog(LOG_NOTICE, "crypto_gq: missing challenge"); return (XEVNT_ID); } /* * Extract the y = k u^r and hash(x = k^b) values from the * response. */ bctx = BN_CTX_new(); y = BN_new(); v = BN_new(); len = ntohl(ep->vallen); ptr = (u_char *)ep->pkt; if ((sdsa = d2i_DSA_SIG(NULL, &ptr, len)) == NULL) { BN_CTX_free(bctx); BN_free(y); BN_free(v); msyslog(LOG_ERR, "crypto_gq: %s", ERR_error_string(ERR_get_error(), NULL)); return (XEVNT_ERR); } /* * Compute v^r y^b mod n. */ if (peer->grpkey == NULL) { msyslog(LOG_NOTICE, "crypto_gq: missing group key"); return (XEVNT_ID); } BN_mod_exp(v, peer->grpkey, peer->iffval, rsa->n, bctx); /* v^r mod n */ BN_mod_exp(y, sdsa->r, rsa->e, rsa->n, bctx); /* y^b mod n */ BN_mod_mul(y, v, y, rsa->n, bctx); /* v^r y^b mod n */ /* * Verify the hash of the result matches hash(x). */ bighash(y, y); temp = BN_cmp(y, sdsa->s); BN_CTX_free(bctx); BN_free(y); BN_free(v); BN_free(peer->iffval); peer->iffval = NULL; DSA_SIG_free(sdsa); if (temp == 0) return (XEVNT_OK); msyslog(LOG_NOTICE, "crypto_gq: identity not verified"); return (XEVNT_ID); } /* *********************************************************************** * * * The following routines implement the Mu-Varadharajan (MV) identity * * scheme * * * *********************************************************************** * * The Mu-Varadharajan (MV) cryptosystem was originally intended when * servers broadcast messages to clients, but clients never send * messages to servers. There is one encryption key for the server and a * separate decryption key for each client. It operated something like a * pay-per-view satellite broadcasting system where the session key is * encrypted by the broadcaster and the decryption keys are held in a * tamperproof set-top box. * * The MV parameters and private encryption key hide in a DSA cuckoo * structure which uses the same parameters, but generated in a * different way. The values are used in an encryption scheme similar to * El Gamal cryptography and a polynomial formed from the expansion of * product terms (x - x[j]), as described in Mu, Y., and V. * Varadharajan: Robust and Secure Broadcasting, Proc. Indocrypt 2001, * 223-231. The paper has significant errors and serious omissions. * * Let q be the product of n distinct primes s1[j] (j = 1...n), where * each s1[j] has m significant bits. Let p be a prime p = 2 * q + 1, so * that q and each s1[j] divide p - 1 and p has M = n * m + 1 * significant bits. Let g be a generator of Zp; that is, gcd(g, p - 1) * = 1 and g^q = 1 mod p. We do modular arithmetic over Zq and then * project into Zp* as exponents of g. Sometimes we have to compute an * inverse b^-1 of random b in Zq, but for that purpose we require * gcd(b, q) = 1. We expect M to be in the 500-bit range and n * relatively small, like 30. These are the parameters of the scheme and * they are expensive to compute. * * We set up an instance of the scheme as follows. A set of random * values x[j] mod q (j = 1...n), are generated as the zeros of a * polynomial of order n. The product terms (x - x[j]) are expanded to * form coefficients a[i] mod q (i = 0...n) in powers of x. These are * used as exponents of the generator g mod p to generate the private * encryption key A. The pair (gbar, ghat) of public server keys and the * pairs (xbar[j], xhat[j]) (j = 1...n) of private client keys are used * to construct the decryption keys. The devil is in the details. * * This routine generates a private server encryption file including the * private encryption key E and partial decryption keys gbar and ghat. * It then generates public client decryption files including the public * keys xbar[j] and xhat[j] for each client j. The partial decryption * files are used to compute the inverse of E. These values are suitably * blinded so secrets are not revealed. * * The distinguishing characteristic of this scheme is the capability to * revoke keys. Included in the calculation of E, gbar and ghat is the * product s = prod(s1[j]) (j = 1...n) above. If the factor s1[j] is * subsequently removed from the product and E, gbar and ghat * recomputed, the jth client will no longer be able to compute E^-1 and * thus unable to decrypt the messageblock. * * How it works * * The scheme goes like this. Bob has the server values (p, E, q, gbar, * ghat) and Alice has the client values (p, xbar, xhat). * * Alice rolls new random nonce r mod p and sends to Bob in the MV * request message. Bob rolls random nonce k mod q, encrypts y = r E^k * mod p and sends (y, gbar^k, ghat^k) to Alice. * * Alice receives the response and computes the inverse (E^k)^-1 from * the partial decryption keys gbar^k, ghat^k, xbar and xhat. She then * decrypts y and verifies it matches the original r. The signed * response binds this knowledge to Bob's private key and the public key * previously received in his certificate. * * crypto_alice3 - construct Alice's challenge in MV scheme * * Returns * XEVNT_OK success * XEVNT_ID bad or missing group key * XEVNT_PUB bad or missing public key */ static int crypto_alice3( struct peer *peer, /* peer pointer */ struct value *vp /* value pointer */ ) { DSA *dsa; /* MV parameters */ BN_CTX *bctx; /* BIGNUM context */ EVP_MD_CTX ctx; /* signature context */ tstamp_t tstamp; u_int len; /* * The identity parameters must have correct format and content. */ if (peer->ident_pkey == NULL) return (XEVNT_ID); if ((dsa = peer->ident_pkey->pkey->pkey.dsa) == NULL) { msyslog(LOG_NOTICE, "crypto_alice3: defective key"); return (XEVNT_PUB); } /* * Roll new random r (0 < r < q). */ if (peer->iffval != NULL) BN_free(peer->iffval); peer->iffval = BN_new(); len = BN_num_bytes(dsa->p); BN_rand(peer->iffval, len * 8, -1, 1); /* r mod p */ bctx = BN_CTX_new(); BN_mod(peer->iffval, peer->iffval, dsa->p, bctx); BN_CTX_free(bctx); /* * Sign and send to Bob. The filestamp is from the local file. */ memset(vp, 0, sizeof(struct value)); tstamp = crypto_time(); vp->tstamp = htonl(tstamp); vp->fstamp = htonl(peer->ident_pkey->fstamp); vp->vallen = htonl(len); vp->ptr = emalloc(len); BN_bn2bin(peer->iffval, vp->ptr); if (tstamp == 0) return (XEVNT_OK); vp->sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)&vp->tstamp, 12); EVP_SignUpdate(&ctx, vp->ptr, len); if (EVP_SignFinal(&ctx, vp->sig, &len, sign_pkey)) vp->siglen = htonl(sign_siglen); return (XEVNT_OK); } /* * crypto_bob3 - construct Bob's response to Alice's challenge * * Returns * XEVNT_OK success * XEVNT_ERR protocol error */ static int crypto_bob3( struct exten *ep, /* extension pointer */ struct value *vp /* value pointer */ ) { DSA *dsa; /* MV parameters */ DSA *sdsa; /* DSA signature context fake */ BN_CTX *bctx; /* BIGNUM context */ EVP_MD_CTX ctx; /* signature context */ tstamp_t tstamp; /* NTP timestamp */ BIGNUM *r, *k, *u; u_char *ptr; u_int len; /* * If the MV parameters are not valid, something awful * happened or we are being tormented. */ if (mvkey_info == NULL) { msyslog(LOG_NOTICE, "crypto_bob3: scheme unavailable"); return (XEVNT_ID); } dsa = mvkey_info->pkey->pkey.dsa; /* * Extract r from the challenge. */ len = ntohl(ep->vallen); if ((r = BN_bin2bn((u_char *)ep->pkt, len, NULL)) == NULL) { msyslog(LOG_ERR, "crypto_bob3: %s", ERR_error_string(ERR_get_error(), NULL)); return (XEVNT_ERR); } /* * Bob rolls random k (0 < k < q), making sure it is not a * factor of q. He then computes y = r A^k and sends (y, gbar^k, * and ghat^k) to Alice. */ bctx = BN_CTX_new(); k = BN_new(); u = BN_new(); sdsa = DSA_new(); sdsa->p = BN_new(); sdsa->q = BN_new(); sdsa->g = BN_new(); while (1) { BN_rand(k, BN_num_bits(dsa->q), 0, 0); BN_mod(k, k, dsa->q, bctx); BN_gcd(u, k, dsa->q, bctx); if (BN_is_one(u)) break; } BN_mod_exp(u, dsa->g, k, dsa->p, bctx); /* A^k r */ BN_mod_mul(sdsa->p, u, r, dsa->p, bctx); BN_mod_exp(sdsa->q, dsa->priv_key, k, dsa->p, bctx); /* gbar */ BN_mod_exp(sdsa->g, dsa->pub_key, k, dsa->p, bctx); /* ghat */ BN_CTX_free(bctx); BN_free(k); BN_free(r); BN_free(u); #ifdef DEBUG if (debug > 1) DSA_print_fp(stdout, sdsa, 0); #endif /* * Encode the values in ASN.1 and sign. The filestamp is from * the local file. */ memset(vp, 0, sizeof(struct value)); tstamp = crypto_time(); vp->tstamp = htonl(tstamp); vp->fstamp = htonl(mvkey_info->fstamp); len = i2d_DSAparams(sdsa, NULL); if (len == 0) { msyslog(LOG_ERR, "crypto_bob3: %s", ERR_error_string(ERR_get_error(), NULL)); DSA_free(sdsa); return (XEVNT_ERR); } vp->vallen = htonl(len); ptr = emalloc(len); vp->ptr = ptr; i2d_DSAparams(sdsa, &ptr); DSA_free(sdsa); if (tstamp == 0) return (XEVNT_OK); vp->sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)&vp->tstamp, 12); EVP_SignUpdate(&ctx, vp->ptr, len); if (EVP_SignFinal(&ctx, vp->sig, &len, sign_pkey)) vp->siglen = htonl(sign_siglen); return (XEVNT_OK); } /* * crypto_mv - verify Bob's response to Alice's challenge * * Returns * XEVNT_OK success * XEVNT_ERR protocol error * XEVNT_FSP bad filestamp * XEVNT_ID bad or missing group key * XEVNT_PUB bad or missing public key */ int crypto_mv( struct exten *ep, /* extension pointer */ struct peer *peer /* peer structure pointer */ ) { DSA *dsa; /* MV parameters */ DSA *sdsa; /* DSA parameters */ BN_CTX *bctx; /* BIGNUM context */ BIGNUM *k, *u, *v; u_int len; const u_char *ptr; int temp; /* * If the MV parameters are not valid or no challenge was sent, * something awful happened or we are being tormented. */ if (peer->ident_pkey == NULL) { msyslog(LOG_NOTICE, "crypto_mv: scheme unavailable"); return (XEVNT_ID); } if (ntohl(ep->fstamp) != peer->ident_pkey->fstamp) { msyslog(LOG_NOTICE, "crypto_mv: invalid filestamp %u", ntohl(ep->fstamp)); return (XEVNT_FSP); } if ((dsa = peer->ident_pkey->pkey->pkey.dsa) == NULL) { msyslog(LOG_NOTICE, "crypto_mv: defective key"); return (XEVNT_PUB); } if (peer->iffval == NULL) { msyslog(LOG_NOTICE, "crypto_mv: missing challenge"); return (XEVNT_ID); } /* * Extract the y, gbar and ghat values from the response. */ bctx = BN_CTX_new(); k = BN_new(); u = BN_new(); v = BN_new(); len = ntohl(ep->vallen); ptr = (u_char *)ep->pkt; if ((sdsa = d2i_DSAparams(NULL, &ptr, len)) == NULL) { msyslog(LOG_ERR, "crypto_mv: %s", ERR_error_string(ERR_get_error(), NULL)); return (XEVNT_ERR); } /* * Compute (gbar^xhat ghat^xbar) mod p. */ BN_mod_exp(u, sdsa->q, dsa->pub_key, dsa->p, bctx); BN_mod_exp(v, sdsa->g, dsa->priv_key, dsa->p, bctx); BN_mod_mul(u, u, v, dsa->p, bctx); BN_mod_mul(u, u, sdsa->p, dsa->p, bctx); /* * The result should match r. */ temp = BN_cmp(u, peer->iffval); BN_CTX_free(bctx); BN_free(k); BN_free(u); BN_free(v); BN_free(peer->iffval); peer->iffval = NULL; DSA_free(sdsa); if (temp == 0) return (XEVNT_OK); msyslog(LOG_NOTICE, "crypto_mv: identity not verified"); return (XEVNT_ID); } /* *********************************************************************** * * * The following routines are used to manipulate certificates * * * *********************************************************************** */ /* * cert_sign - sign x509 certificate equest and update value structure. * * The certificate request includes a copy of the host certificate, * which includes the version number, subject name and public key of the * host. The resulting certificate includes these values plus the * serial number, issuer name and valid interval of the server. The * valid interval extends from the current time to the same time one * year hence. This may extend the life of the signed certificate beyond * that of the signer certificate. * * It is convenient to use the NTP seconds of the current time as the * serial number. In the value structure the timestamp is the current * time and the filestamp is taken from the extension field. Note this * routine is called only when the client clock is synchronized to a * proventic source, so timestamp comparisons are valid. * * The host certificate is valid from the time it was generated for a * period of one year. A signed certificate is valid from the time of * signature for a period of one year, but only the host certificate (or * sign certificate if used) is actually used to encrypt and decrypt * signatures. The signature trail is built from the client via the * intermediate servers to the trusted server. Each signature on the * trail must be valid at the time of signature, but it could happen * that a signer certificate expire before the signed certificate, which * remains valid until its expiration. * * Returns * XEVNT_OK success * XEVNT_CRT bad or missing certificate * XEVNT_PER host certificate expired * XEVNT_PUB bad or missing public key * XEVNT_VFY certificate not verified */ static int cert_sign( struct exten *ep, /* extension field pointer */ struct value *vp /* value pointer */ ) { X509 *req; /* X509 certificate request */ X509 *cert; /* X509 certificate */ X509_EXTENSION *ext; /* certificate extension */ ASN1_INTEGER *serial; /* serial number */ X509_NAME *subj; /* distinguished (common) name */ EVP_PKEY *pkey; /* public key */ EVP_MD_CTX ctx; /* message digest context */ tstamp_t tstamp; /* NTP timestamp */ u_int len; u_char *ptr; int i, temp; /* * Decode ASN.1 objects and construct certificate structure. * Make sure the system clock is synchronized to a proventic * source. */ tstamp = crypto_time(); if (tstamp == 0) return (XEVNT_TSP); ptr = (u_char *)ep->pkt; if ((req = d2i_X509(NULL, &ptr, ntohl(ep->vallen))) == NULL) { msyslog(LOG_ERR, "cert_sign: %s", ERR_error_string(ERR_get_error(), NULL)); return (XEVNT_CRT); } /* * Extract public key and check for errors. */ if ((pkey = X509_get_pubkey(req)) == NULL) { msyslog(LOG_ERR, "cert_sign: %s", ERR_error_string(ERR_get_error(), NULL)); X509_free(req); return (XEVNT_PUB); } /* * Generate X509 certificate signed by this server. If this is a * trusted host, the issuer name is the group name; otherwise, * it is the host name. Also copy any extensions that might be * present. */ cert = X509_new(); X509_set_version(cert, X509_get_version(req)); serial = ASN1_INTEGER_new(); ASN1_INTEGER_set(serial, tstamp); X509_set_serialNumber(cert, serial); X509_gmtime_adj(X509_get_notBefore(cert), 0L); X509_gmtime_adj(X509_get_notAfter(cert), YEAR); subj = X509_get_issuer_name(cert); X509_NAME_add_entry_by_txt(subj, "commonName", MBSTRING_ASC, hostval.ptr, strlen(hostval.ptr), -1, 0); subj = X509_get_subject_name(req); X509_set_subject_name(cert, subj); X509_set_pubkey(cert, pkey); ext = X509_get_ext(req, 0); temp = X509_get_ext_count(req); for (i = 0; i < temp; i++) { ext = X509_get_ext(req, i); X509_add_ext(cert, ext, -1); } X509_free(req); /* * Sign and verify the client certificate, but only if the host * certificate has not expired. */ if (tstamp < cert_host->first || tstamp > cert_host->last) { X509_free(cert); return (XEVNT_PER); } X509_sign(cert, sign_pkey, sign_digest); if (X509_verify(cert, sign_pkey) <= 0) { msyslog(LOG_ERR, "cert_sign: %s", ERR_error_string(ERR_get_error(), NULL)); X509_free(cert); return (XEVNT_VFY); } len = i2d_X509(cert, NULL); /* * Build and sign the value structure. We have to sign it here, * since the response has to be returned right away. This is a * clogging hazard. */ memset(vp, 0, sizeof(struct value)); vp->tstamp = htonl(tstamp); vp->fstamp = ep->fstamp; vp->vallen = htonl(len); vp->ptr = emalloc(len); ptr = vp->ptr; i2d_X509(cert, &ptr); vp->siglen = 0; if (tstamp != 0) { vp->sig = emalloc(sign_siglen); EVP_SignInit(&ctx, sign_digest); EVP_SignUpdate(&ctx, (u_char *)vp, 12); EVP_SignUpdate(&ctx, vp->ptr, len); if (EVP_SignFinal(&ctx, vp->sig, &len, sign_pkey)) vp->siglen = htonl(sign_siglen); } #ifdef DEBUG if (debug > 1) X509_print_fp(stdout, cert); #endif X509_free(cert); return (XEVNT_OK); } /* * cert_install - install certificate in certificate cache * * This routine encodes an extension field into a certificate info/value * structure. It searches the certificate list for duplicates and * expunges whichever is older. Finally, it inserts this certificate * first on the list. * * Returns certificate info pointer if valid, NULL if not. */ struct cert_info * cert_install( struct exten *ep, /* cert info/value */ struct peer *peer /* peer structure */ ) { struct cert_info *cp, *xp, **zp; /* * Parse and validate the signed certificate. If valid, * construct the info/value structure; otherwise, scamper home * empty handed. */ if ((cp = cert_parse((u_char *)ep->pkt, (long)ntohl(ep->vallen), (tstamp_t)ntohl(ep->fstamp))) == NULL) return (NULL); /* * Scan certificate list looking for another certificate with * the same subject and issuer. If another is found with the * same or older filestamp, unlink it and return the goodies to * the heap. If another is found with a later filestamp, discard * the new one and leave the building with the old one. * * Make a note to study this issue again. An earlier certificate * with a long lifetime might be overtaken by a later * certificate with a short lifetime, thus invalidating the * earlier signature. However, we gotta find a way to leak old * stuff from the cache, so we do it anyway. */ zp = &cinfo; for (xp = cinfo; xp != NULL; xp = xp->link) { if (strcmp(cp->subject, xp->subject) == 0 && strcmp(cp->issuer, xp->issuer) == 0) { if (ntohl(cp->cert.fstamp) <= ntohl(xp->cert.fstamp)) { cert_free(cp); cp = xp; } else { *zp = xp->link; cert_free(xp); xp = NULL; } break; } zp = &xp->link; } if (xp == NULL) { cp->link = cinfo; cinfo = cp; } cp->flags |= CERT_VALID; crypto_update(); return (cp); } /* * cert_hike - verify the signature using the issuer public key * * Returns * XEVNT_OK success * XEVNT_CRT bad or missing certificate * XEVNT_PER host certificate expired * XEVNT_VFY certificate not verified */ int cert_hike( struct peer *peer, /* peer structure pointer */ struct cert_info *yp /* issuer certificate */ ) { struct cert_info *xp; /* subject certificate */ X509 *cert; /* X509 certificate */ u_char *ptr; /* * Save the issuer on the new certificate, but remember the old * one. */ if (peer->issuer != NULL) free(peer->issuer); peer->issuer = emalloc(strlen(yp->issuer) + 1); strcpy(peer->issuer, yp->issuer); xp = peer->xinfo; peer->xinfo = yp; /* * If subject Y matches issuer Y, then the certificate trail is * complete. If Y is not trusted, the server certificate has yet * been signed, so keep trying. Otherwise, save the group key * and light the valid bit. If the host certificate is trusted, * do not execute a sign exchange. If no identity scheme is in * use, light the identity and proventic bits. */ if (strcmp(yp->subject, yp->issuer) == 0) { if (!(yp->flags & CERT_TRUST)) return (XEVNT_OK); peer->grpkey = yp->grpkey; peer->crypto |= CRYPTO_FLAG_CERT; if (!(peer->crypto & CRYPTO_FLAG_MASK)) peer->crypto |= CRYPTO_FLAG_VRFY | CRYPTO_FLAG_PROV; /* * If the server has an an identity scheme, fetch the * identity credentials. If not, the identity is * verified only by the trusted certificate. The next * signature will set the server proventic. */ if (!(peer->crypto & CRYPTO_FLAG_MASK) || sys_groupname == NULL) peer->crypto |= CRYPTO_FLAG_VRFY; } /* * If X exists, verify signature X using public key Y. */ if (xp == NULL) return (XEVNT_OK); ptr = (u_char *)xp->cert.ptr; cert = d2i_X509(NULL, &ptr, ntohl(xp->cert.vallen)); if (cert == NULL) { xp->flags |= CERT_ERROR; return (XEVNT_CRT); } if (X509_verify(cert, yp->pkey) <= 0) { X509_free(cert); xp->flags |= CERT_ERROR; return (XEVNT_VFY); } X509_free(cert); /* * Signature X is valid only if it begins during the * lifetime of Y. */ if (xp->first < yp->first || xp->first > yp->last) { xp->flags |= CERT_ERROR; return (XEVNT_PER); } xp->flags |= CERT_SIGN; return (XEVNT_OK); } /* * cert_parse - parse x509 certificate and create info/value structures. * * The server certificate includes the version number, issuer name, * subject name, public key and valid date interval. If the issuer name * is the same as the subject name, the certificate is self signed and * valid only if the server is configured as trustable. If the names are * different, another issuer has signed the server certificate and * vouched for it. In this case the server certificate is valid if * verified by the issuer public key. * * Returns certificate info/value pointer if valid, NULL if not. */ struct cert_info * /* certificate information structure */ cert_parse( u_char *asn1cert, /* X509 certificate */ long len, /* certificate length */ tstamp_t fstamp /* filestamp */ ) { X509 *cert; /* X509 certificate */ X509_EXTENSION *ext; /* X509v3 extension */ struct cert_info *ret; /* certificate info/value */ BIO *bp; char pathbuf[MAXFILENAME]; u_char *ptr; int temp, cnt, i; /* * Decode ASN.1 objects and construct certificate structure. */ ptr = asn1cert; if ((cert = d2i_X509(NULL, &ptr, len)) == NULL) { msyslog(LOG_ERR, "cert_parse: %s", ERR_error_string(ERR_get_error(), NULL)); return (NULL); } #ifdef DEBUG if (debug > 1) X509_print_fp(stdout, cert); #endif /* * Extract version, subject name and public key. */ ret = emalloc(sizeof(struct cert_info)); memset(ret, 0, sizeof(struct cert_info)); if ((ret->pkey = X509_get_pubkey(cert)) == NULL) { msyslog(LOG_ERR, "cert_parse: %s", ERR_error_string(ERR_get_error(), NULL)); cert_free(ret); X509_free(cert); return (NULL); } ret->version = X509_get_version(cert); X509_NAME_oneline(X509_get_subject_name(cert), pathbuf, MAXFILENAME); ptr = strstr(pathbuf, "CN="); if (ptr == NULL) { msyslog(LOG_NOTICE, "cert_parse: invalid subject %s", pathbuf); cert_free(ret); X509_free(cert); return (NULL); } ret->subject = estrdup(ptr + 3); /* * Extract remaining objects. Note that the NTP serial number is * the NTP seconds at the time of signing, but this might not be * the case for other authority. We don't bother to check the * objects at this time, since the real crunch can happen only * when the time is valid but not yet certificated. */ ret->nid = OBJ_obj2nid(cert->cert_info->signature->algorithm); ret->digest = (const EVP_MD *)EVP_get_digestbynid(ret->nid); ret->serial = (u_long)ASN1_INTEGER_get(X509_get_serialNumber(cert)); X509_NAME_oneline(X509_get_issuer_name(cert), pathbuf, MAXFILENAME); if ((ptr = strstr(pathbuf, "CN=")) == NULL) { msyslog(LOG_NOTICE, "cert_parse: invalid issuer %s", pathbuf); cert_free(ret); X509_free(cert); return (NULL); } ret->issuer = estrdup(ptr + 3); ret->first = asn2ntp(X509_get_notBefore(cert)); ret->last = asn2ntp(X509_get_notAfter(cert)); /* * Extract extension fields. These are ad hoc ripoffs of * currently assigned functions and will certainly be changed * before prime time. */ cnt = X509_get_ext_count(cert); for (i = 0; i < cnt; i++) { ext = X509_get_ext(cert, i); temp = OBJ_obj2nid(ext->object); switch (temp) { /* * If a key_usage field is present, we decode whether * this is a trusted or private certificate. This is * dorky; all we want is to compare NIDs, but OpenSSL * insists on BIO text strings. */ case NID_ext_key_usage: bp = BIO_new(BIO_s_mem()); X509V3_EXT_print(bp, ext, 0, 0); BIO_gets(bp, pathbuf, MAXFILENAME); BIO_free(bp); if (strcmp(pathbuf, "Trust Root") == 0) ret->flags |= CERT_TRUST; else if (strcmp(pathbuf, "Private") == 0) ret->flags |= CERT_PRIV; #if DEBUG if (debug) printf("cert_parse: %s: %s\n", OBJ_nid2ln(temp), pathbuf); #endif break; /* * If a NID_subject_key_identifier field is present, it * contains the GQ public key. */ case NID_subject_key_identifier: ret->grpkey = BN_bin2bn(&ext->value->data[2], ext->value->length - 2, NULL); /* fall through */ #if DEBUG default: if (debug) printf("cert_parse: %s\n", OBJ_nid2ln(temp)); #endif } } if (strcmp(ret->subject, ret->issuer) == 0) { /* * If certificate is self signed, verify signature. */ if (X509_verify(cert, ret->pkey) <= 0) { msyslog(LOG_NOTICE, "cert_parse: signature not verified %s", ret->subject); cert_free(ret); X509_free(cert); return (NULL); } } else { /* * Check for a certificate loop. */ if (strcmp(hostval.ptr, ret->issuer) == 0) { msyslog(LOG_NOTICE, "cert_parse: certificate trail loop %s", ret->subject); cert_free(ret); X509_free(cert); return (NULL); } } /* * Verify certificate valid times. Note that certificates cannot * be retroactive. */ if (ret->first > ret->last || ret->first < fstamp) { msyslog(LOG_NOTICE, "cert_parse: invalid times %s first %u last %u fstamp %u", ret->subject, ret->first, ret->last, fstamp); cert_free(ret); X509_free(cert); return (NULL); } /* * Build the value structure to sign and send later. */ ret->cert.fstamp = htonl(fstamp); ret->cert.vallen = htonl(len); ret->cert.ptr = emalloc(len); memcpy(ret->cert.ptr, asn1cert, len); X509_free(cert); return (ret); } /* * cert_free - free certificate information structure */ void cert_free( struct cert_info *cinf /* certificate info/value structure */ ) { if (cinf->pkey != NULL) EVP_PKEY_free(cinf->pkey); if (cinf->subject != NULL) free(cinf->subject); if (cinf->issuer != NULL) free(cinf->issuer); if (cinf->grpkey != NULL) BN_free(cinf->grpkey); value_free(&cinf->cert); free(cinf); } /* * crypto_key - load cryptographic parameters and keys * * This routine searches the key cache for matching name in the form * ntpkey_<key>_<name>, where <key> is one of host, sign, iff, gq, mv, * and <name> is the host/group name. If not found, it tries to load a * PEM-encoded file of the same name and extracts the filestamp from * the first line of the file name. It returns the key pointer if valid, * NULL if not. */ static struct pkey_info * crypto_key( char *cp, /* file name */ char *passwd1, /* password */ sockaddr_u *addr /* IP address */ ) { FILE *str; /* file handle */ struct pkey_info *pkp; /* generic key */ EVP_PKEY *pkey = NULL; /* public/private key */ tstamp_t fstamp; char filename[MAXFILENAME]; /* name of key file */ char linkname[MAXFILENAME]; /* filestamp buffer) */ char statstr[NTP_MAXSTRLEN]; /* statistics for filegen */ char *ptr; /* * Search the key cache for matching key and name. */ for (pkp = pkinfo; pkp != NULL; pkp = pkp->link) { if (strcmp(cp, pkp->name) == 0) return (pkp); } /* * Open the key file. If the first character of the file name is * not '/', prepend the keys directory string. If something goes * wrong, abandon ship. */ if (*cp == '/') strcpy(filename, cp); else snprintf(filename, MAXFILENAME, "%s/%s", keysdir, cp); str = fopen(filename, "r"); if (str == NULL) return (NULL); /* * Read the filestamp, which is contained in the first line. */ if ((ptr = fgets(linkname, MAXFILENAME, str)) == NULL) { msyslog(LOG_ERR, "crypto_key: empty file %s", filename); fclose(str); return (NULL); } if ((ptr = strrchr(ptr, '.')) == NULL) { msyslog(LOG_ERR, "crypto_key: no filestamp %s", filename); fclose(str); return (NULL); } if (sscanf(++ptr, "%u", &fstamp) != 1) { msyslog(LOG_ERR, "crypto_key: invalid filestamp %s", filename); fclose(str); return (NULL); } /* * Read and decrypt PEM-encoded private key. If it fails to * decrypt, game over. */ pkey = PEM_read_PrivateKey(str, NULL, NULL, passwd1); fclose(str); if (pkey == NULL) { msyslog(LOG_ERR, "crypto_key: %s", ERR_error_string(ERR_get_error(), NULL)); exit (-1); } /* * Make a new entry in the key cache. */ pkp = emalloc(sizeof(struct pkey_info)); pkp->link = pkinfo; pkinfo = pkp; pkp->pkey = pkey; pkp->name = emalloc(strlen(cp) + 1); pkp->fstamp = fstamp; strcpy(pkp->name, cp); /* * Leave tracks in the cryptostats. */ if ((ptr = strrchr(linkname, '\n')) != NULL) *ptr = '\0'; snprintf(statstr, NTP_MAXSTRLEN, "%s mod %d", &linkname[2], EVP_PKEY_size(pkey) * 8); record_crypto_stats(addr, statstr); #ifdef DEBUG if (debug) printf("crypto_key: %s\n", statstr); if (debug > 1) { if (pkey->type == EVP_PKEY_DSA) DSA_print_fp(stdout, pkey->pkey.dsa, 0); else if (pkey->type == EVP_PKEY_RSA) RSA_print_fp(stdout, pkey->pkey.rsa, 0); } #endif return (pkp); } /* *********************************************************************** * * * The following routines are used only at initialization time * * * *********************************************************************** */ /* * crypto_cert - load certificate from file * * This routine loads an X.509 RSA or DSA certificate from a file and * constructs a info/cert value structure for this machine. The * structure includes a filestamp extracted from the file name. Later * the certificate can be sent to another machine on request. * * Returns certificate info/value pointer if valid, NULL if not. */ static struct cert_info * /* certificate information */ crypto_cert( char *cp /* file name */ ) { struct cert_info *ret; /* certificate information */ FILE *str; /* file handle */ char filename[MAXFILENAME]; /* name of certificate file */ char linkname[MAXFILENAME]; /* filestamp buffer */ char statstr[NTP_MAXSTRLEN]; /* statistics for filegen */ tstamp_t fstamp; /* filestamp */ long len; char *ptr; char *name, *header; u_char *data; /* * Open the certificate file. If the first character of the file * name is not '/', prepend the keys directory string. If * something goes wrong, abandon ship. */ if (*cp == '/') strcpy(filename, cp); else snprintf(filename, MAXFILENAME, "%s/%s", keysdir, cp); str = fopen(filename, "r"); if (str == NULL) return (NULL); /* * Read the filestamp, which is contained in the first line. */ if ((ptr = fgets(linkname, MAXFILENAME, str)) == NULL) { msyslog(LOG_ERR, "crypto_cert: empty file %s", filename); fclose(str); return (NULL); } if ((ptr = strrchr(ptr, '.')) == NULL) { msyslog(LOG_ERR, "crypto_cert: no filestamp %s\n", filename); fclose(str); return (NULL); } if (sscanf(++ptr, "%u", &fstamp) != 1) { msyslog(LOG_ERR, "crypto_cert: invalid filestamp %s\n", filename); fclose(str); return (NULL); } /* * Read PEM-encoded certificate and install. */ if (!PEM_read(str, &name, &header, &data, &len)) { msyslog(LOG_ERR, "crypto_cert: %s\n", ERR_error_string(ERR_get_error(), NULL)); fclose(str); return (NULL); } fclose(str); free(header); if (strcmp(name, "CERTIFICATE") != 0) { msyslog(LOG_NOTICE, "crypto_cert: wrong PEM type %s", name); free(name); free(data); return (NULL); } free(name); /* * Parse certificate and generate info/value structure. The * pointer and copy nonsense is due something broken in Solaris. */ ret = cert_parse(data, len, fstamp); free(data); if (ret == NULL) return (NULL); if ((ptr = strrchr(linkname, '\n')) != NULL) *ptr = '\0'; snprintf(statstr, NTP_MAXSTRLEN, "%s 0x%x len %lu", &linkname[2], ret->flags, len); record_crypto_stats(NULL, statstr); #ifdef DEBUG if (debug) printf("crypto_cert: %s\n", statstr); #endif return (ret); } /* * crypto_setup - load keys, certificate and identity parameters * * This routine loads the public/private host key and certificate. If * available, it loads the public/private sign key, which defaults to * the host key. The host key must be RSA, but the sign key can be * either RSA or DSA. If a trusted certificate, it loads the identity * parameters. In either case, the public key on the certificate must * agree with the sign key. * * Required but missing files and inconsistent data and errors are * fatal. Allowing configuration to continue would be hazardous and * require really messy error checks. */ void crypto_setup(void) { struct pkey_info *pinfo; /* private/public key */ char filename[MAXFILENAME]; /* file name buffer */ char * randfile; char statstr[NTP_MAXSTRLEN]; /* statistics for filegen */ l_fp seed; /* crypto PRNG seed as NTP timestamp */ u_int len; int bytes; u_char *ptr; /* * Check for correct OpenSSL version and avoid initialization in * the case of multiple crypto commands. */ if (crypto_flags & CRYPTO_FLAG_ENAB) { msyslog(LOG_NOTICE, "crypto_setup: spurious crypto command"); return; } ssl_check_version(); /* * Load required random seed file and seed the random number * generator. Be default, it is found as .rnd in the user home * directory. The root home directory may be / or /root, * depending on the system. Wiggle the contents a bit and write * it back so the sequence does not repeat when we next restart. */ if (!RAND_status()) { if (rand_file == NULL) { RAND_file_name(filename, sizeof(filename)); randfile = filename; } else if (*rand_file != '/') { snprintf(filename, sizeof(filename), "%s/%s", keysdir, rand_file); randfile = filename; } else randfile = rand_file; if ((bytes = RAND_load_file(randfile, -1)) == 0) { msyslog(LOG_ERR, "crypto_setup: random seed file %s missing", randfile); exit (-1); } get_systime(&seed); RAND_seed(&seed, sizeof(l_fp)); RAND_write_file(randfile); #ifdef DEBUG if (debug) printf( "crypto_setup: OpenSSL version %lx random seed file %s bytes read %d\n", SSLeay(), randfile, bytes); #endif } /* * Initialize structures. */ if (sys_hostname == NULL) { gethostname(filename, MAXFILENAME); sys_hostname = emalloc(strlen(filename) + 1); strcpy(sys_hostname, filename); } if (passwd == NULL) passwd = sys_hostname; memset(&hostval, 0, sizeof(hostval)); memset(&pubkey, 0, sizeof(pubkey)); memset(&tai_leap, 0, sizeof(tai_leap)); /* * Load required host key from file "ntpkey_host_<hostname>". If * no host key file is not found or has invalid password, life * as we know it ends. The host key also becomes the default * sign key. */ snprintf(filename, MAXFILENAME, "ntpkey_host_%s", sys_hostname); pinfo = crypto_key(filename, passwd, NULL); if (pinfo == NULL) { msyslog(LOG_ERR, "crypto_setup: host key file %s not found or corrupt", filename); exit (-1); } if (pinfo->pkey->type != EVP_PKEY_RSA) { msyslog(LOG_ERR, "crypto_setup: host key is not RSA key type"); exit (-1); } host_pkey = pinfo->pkey; sign_pkey = host_pkey; hostval.fstamp = htonl(pinfo->fstamp); /* * Construct public key extension field for agreement scheme. */ len = i2d_PublicKey(host_pkey, NULL); ptr = emalloc(len); pubkey.ptr = ptr; i2d_PublicKey(host_pkey, &ptr); pubkey.fstamp = hostval.fstamp; pubkey.vallen = htonl(len); /* * Load optional sign key from file "ntpkey_sign_<hostname>". If * available, it becomes the sign key. */ snprintf(filename, MAXFILENAME, "ntpkey_sign_%s", sys_hostname); pinfo = crypto_key(filename, passwd, NULL); if (pinfo != NULL) sign_pkey = pinfo->pkey; /* * Load required certificate from file "ntpkey_cert_<hostname>". */ snprintf(filename, MAXFILENAME, "ntpkey_cert_%s", sys_hostname); cinfo = crypto_cert(filename); if (cinfo == NULL) { msyslog(LOG_ERR, "crypto_setup: certificate file %s not found or corrupt", filename); exit (-1); } cert_host = cinfo; sign_digest = cinfo->digest; sign_siglen = EVP_PKEY_size(sign_pkey); if (cinfo->flags & CERT_PRIV) crypto_flags |= CRYPTO_FLAG_PRIV; /* * The certificate must be self-signed. */ if (strcmp(cinfo->subject, cinfo->issuer) != 0) { msyslog(LOG_ERR, "crypto_setup: certificate %s is not self-signed", filename); exit (-1); } hostval.vallen = htonl(strlen(cinfo->subject)); hostval.ptr = cinfo->subject; /* * If trusted certificate, the subject name must match the group * name. */ if (cinfo->flags & CERT_TRUST) { if (sys_groupname == NULL) { sys_groupname = hostval.ptr; } else if (strcmp(hostval.ptr, sys_groupname) != 0) { msyslog(LOG_ERR, "crypto_setup: trusted certificate name %s does not match group name %s", hostval.ptr, sys_groupname); exit (-1); } } if (sys_groupname != NULL) { /* * Load optional IFF parameters from file * "ntpkey_iffkey_<groupname>". */ snprintf(filename, MAXFILENAME, "ntpkey_iffkey_%s", sys_groupname); iffkey_info = crypto_key(filename, passwd, NULL); if (iffkey_info != NULL) crypto_flags |= CRYPTO_FLAG_IFF; /* * Load optional GQ parameters from file * "ntpkey_gqkey_<groupname>". */ snprintf(filename, MAXFILENAME, "ntpkey_gqkey_%s", sys_groupname); gqkey_info = crypto_key(filename, passwd, NULL); if (gqkey_info != NULL) crypto_flags |= CRYPTO_FLAG_GQ; /* * Load optional MV parameters from file * "ntpkey_mvkey_<groupname>". */ snprintf(filename, MAXFILENAME, "ntpkey_mvkey_%s", sys_groupname); mvkey_info = crypto_key(filename, passwd, NULL); if (mvkey_info != NULL) crypto_flags |= CRYPTO_FLAG_MV; } /* * We met the enemy and he is us. Now strike up the dance. */ crypto_flags |= CRYPTO_FLAG_ENAB | (cinfo->nid << 16); snprintf(statstr, NTP_MAXSTRLEN, "setup 0x%x host %s %s", crypto_flags, sys_hostname, OBJ_nid2ln(cinfo->nid)); record_crypto_stats(NULL, statstr); #ifdef DEBUG if (debug) printf("crypto_setup: %s\n", statstr); #endif } /* * crypto_config - configure data from the crypto command. */ void crypto_config( int item, /* configuration item */ char *cp /* item name */ ) { int nid; #ifdef DEBUG if (debug > 1) printf("crypto_config: item %d %s\n", item, cp); #endif switch (item) { /* * Set host name (host). */ case CRYPTO_CONF_PRIV: sys_hostname = emalloc(strlen(cp) + 1); strcpy(sys_hostname, cp); break; /* * Set group name (ident). */ case CRYPTO_CONF_IDENT: sys_groupname = emalloc(strlen(cp) + 1); strcpy(sys_groupname, cp); break; /* * Set private key password (pw). */ case CRYPTO_CONF_PW: passwd = emalloc(strlen(cp) + 1); strcpy(passwd, cp); break; /* * Set random seed file name (randfile). */ case CRYPTO_CONF_RAND: rand_file = emalloc(strlen(cp) + 1); strcpy(rand_file, cp); break; /* * Set message digest NID. */ case CRYPTO_CONF_NID: nid = OBJ_sn2nid(cp); if (nid == 0) msyslog(LOG_ERR, "crypto_config: invalid digest name %s", cp); else crypto_nid = nid; break; } } # else int ntp_crypto_bs_pubkey; # endif /* OPENSSL */