int sftp_mac_set_read_key(pool *p, const EVP_MD *hash, const BIGNUM *k,
const char *h, uint32_t hlen) {
const unsigned char *id = NULL;
char *buf, *ptr;
uint32_t buflen, bufsz, id_len;
char letter;
size_t blocksz;
struct sftp_mac *mac;
HMAC_CTX *mac_ctx;
switch_read_mac();
mac = &(read_macs[read_mac_idx]);
mac_ctx = &(read_ctxs[read_mac_idx]);
bufsz = buflen = 1024;
ptr = buf = sftp_msg_getbuf(p, bufsz);
/* Need to use SSH2-style format of K for the key. */
sftp_msg_write_mpint(&buf, &buflen, k);
id_len = sftp_session_get_id(&id);
/* HASH(K || H || "E" || session_id) */
letter = 'E';
set_mac_key(mac, hash, ptr, (bufsz - buflen), h, hlen, &letter, id, id_len);
#if OPENSSL_VERSION_NUMBER > 0x000907000L
HMAC_CTX_init(mac_ctx);
# if OPENSSL_VERSION_NUMBER >= 0x10000001L
if (HMAC_Init_ex(mac_ctx, mac->key, mac->key_len, mac->digest, NULL) != 1) {
pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error initializing HMAC: %s", sftp_crypto_get_errors());
errno = EPERM;
return -1;
}
# else
HMAC_Init_ex(mac_ctx, mac->key, mac->key_len, mac->digest, NULL);
# endif /* OpenSSL-1.0.0 and later */
#else
/* Reset the HMAC context. */
HMAC_Init(mac_ctx, NULL, 0, NULL);
HMAC_Init(mac_ctx, mac->key, mac->key_len, mac->digest);
#endif
if (mac->mac_len == 0) {
blocksz = EVP_MD_size(mac->digest);
} else {
blocksz = mac->mac_len;
}
pr_memscrub(ptr, bufsz);
sftp_mac_set_block_size(blocksz);
return 0;
}
int sftp_mac_set_write_key(pool *p, const EVP_MD *hash, const BIGNUM *k,
const char *h, uint32_t hlen) {
const unsigned char *id = NULL;
char *buf, *ptr;
uint32_t buflen, bufsz, id_len;
char letter;
struct sftp_mac *mac;
HMAC_CTX *mac_ctx;
switch_write_mac();
mac = &(write_macs[write_mac_idx]);
mac_ctx = &(write_ctxs[write_mac_idx]);
bufsz = buflen = 1024;
ptr = buf = sftp_msg_getbuf(p, bufsz);
/* Need to use SSH2-style format of K for the key. */
sftp_msg_write_mpint(&buf, &buflen, k);
id_len = sftp_session_get_id(&id);
/* HASH(K || H || "F" || session_id) */
letter = 'F';
set_mac_key(mac, hash, ptr, (bufsz - buflen), h, hlen, &letter, id, id_len);
#if OPENSSL_VERSION_NUMBER > 0x000907000L
HMAC_CTX_init(mac_ctx);
#else
/* Reset the HMAC context. */
HMAC_Init(mac_ctx, NULL, 0, NULL);
#endif
HMAC_Init(mac_ctx, mac->key, mac->key_len, mac->digest);
pr_memscrub(ptr, bufsz);
return 0;
}
int sftp_auth_hostbased(struct ssh2_packet *pkt, cmd_rec *pass_cmd,
const char *orig_user, const char *user, const char *service,
unsigned char **buf, uint32_t *buflen, int *send_userauth_fail) {
struct passwd *pw;
char *hostkey_algo, *host_fqdn, *host_user, *host_user_utf8;
const char *fp = NULL;
unsigned char *hostkey_data, *signature_data;
unsigned char *buf2, *ptr2;
const unsigned char *id;
uint32_t buflen2, bufsz2, hostkey_datalen, id_len, signature_len;
enum sftp_key_type_e pubkey_type;
if (pr_cmd_dispatch_phase(pass_cmd, PRE_CMD, 0) < 0) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"authentication request for user '%s' blocked by '%s' handler",
orig_user, (char *) pass_cmd->argv[0]);
pr_cmd_dispatch_phase(pass_cmd, POST_CMD_ERR, 0);
pr_cmd_dispatch_phase(pass_cmd, LOG_CMD_ERR, 0);
*send_userauth_fail = TRUE;
errno = EPERM;
return 0;
}
hostkey_algo = sftp_msg_read_string(pkt->pool, buf, buflen);
if (hostkey_algo == NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"missing required host key algorithm, rejecting request");
*send_userauth_fail = TRUE;
errno = EINVAL;
return 0;
}
hostkey_datalen = sftp_msg_read_int(pkt->pool, buf, buflen);
hostkey_data = sftp_msg_read_data(pkt->pool, buf, buflen, hostkey_datalen);
host_fqdn = sftp_msg_read_string(pkt->pool, buf, buflen);
host_user_utf8 = sftp_msg_read_string(pkt->pool, buf, buflen);
host_user = sftp_utf8_decode_str(pkt->pool, host_user_utf8);
signature_len = sftp_msg_read_int(pkt->pool, buf, buflen);
signature_data = sftp_msg_read_data(pkt->pool, buf, buflen, signature_len);
pr_trace_msg(trace_channel, 9,
"client sent '%s' host key, FQDN %s, and remote user '%s'",
hostkey_algo, host_fqdn, host_user);
if (strncmp(hostkey_algo, "ssh-rsa", 8) == 0) {
pubkey_type = SFTP_KEY_RSA;
} else if (strncmp(hostkey_algo, "ssh-dss", 8) == 0) {
pubkey_type = SFTP_KEY_DSA;
#ifdef PR_USE_OPENSSL_ECC
} else if (strncmp(hostkey_algo, "ecdsa-sha2-nistp256", 20) == 0) {
pubkey_type = SFTP_KEY_ECDSA_256;
} else if (strncmp(hostkey_algo, "ecdsa-sha2-nistp256", 20) == 0) {
pubkey_type = SFTP_KEY_ECDSA_384;
} else if (strncmp(hostkey_algo, "ecdsa-sha2-nistp256", 20) == 0) {
pubkey_type = SFTP_KEY_ECDSA_521;
#endif /* PR_USE_OPENSSL_ECC */
/* XXX Need to support X509v3 certs here */
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"unsupported host key algorithm '%s' requested, rejecting request",
hostkey_algo);
*send_userauth_fail = TRUE;
errno = EINVAL;
return 0;
}
if (sftp_keys_verify_pubkey_type(pkt->pool, hostkey_data, hostkey_datalen,
pubkey_type) != TRUE) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"unable to verify that given host key matches given '%s' algorithm",
hostkey_algo);
*send_userauth_fail = TRUE;
errno = EINVAL;
return 0;
}
#ifdef OPENSSL_FIPS
if (FIPS_mode()) {
fp = sftp_keys_get_fingerprint(pkt->pool, hostkey_data, hostkey_datalen,
SFTP_KEYS_FP_DIGEST_SHA1);
if (fp != NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"public key SHA1 fingerprint: %s", fp);
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error obtaining public key SHA1 fingerprint: %s", strerror(errno));
}
} else {
#endif /* OPENSSL_FIPS */
fp = sftp_keys_get_fingerprint(pkt->pool, hostkey_data, hostkey_datalen,
SFTP_KEYS_FP_DIGEST_MD5);
if (fp != NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"public key MD5 fingerprint: %s", fp);
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error obtaining public key MD5 fingerprint: %s", strerror(errno));
}
#ifdef OPENSSL_FIPS
}
#endif /* OPENSSL_FIPS */
pw = pr_auth_getpwnam(pkt->pool, user);
if (pw == NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"no account for user '%s' found", user);
pr_log_auth(PR_LOG_NOTICE,
"USER %s: no such user found from %s [%s] to %s:%d", user,
session.c->remote_name, pr_netaddr_get_ipstr(session.c->remote_addr),
pr_netaddr_get_ipstr(session.c->local_addr), session.c->local_port);
*send_userauth_fail = TRUE;
errno = ENOENT;
return 0;
}
/* XXX Should we check the given FQDN here against the client's actual
* DNS name and/or IP address? Or leave that up to the keystore's
* verify_host_key() function?
*/
if (sftp_blacklist_reject_key(pkt->pool, hostkey_data, hostkey_datalen)) {
*send_userauth_fail = TRUE;
errno = EACCES;
return 0;
}
/* The client signed the request as well; we need to authenticate the
* host with the given key now. If that succeeds, we use the signature to
* verify the request. And if that succeeds, then we're done authenticating.
*/
if (sftp_keystore_verify_host_key(pkt->pool, user, host_fqdn, host_user,
hostkey_data, hostkey_datalen) < 0) {
*send_userauth_fail = TRUE;
errno = EACCES;
return 0;
}
/* Make sure the signature matches as well. */
id_len = sftp_session_get_id(&id);
/* XXX Is this buffer large enough? Too large? */
bufsz2 = buflen2 = 2048;
ptr2 = buf2 = sftp_msg_getbuf(pkt->pool, bufsz2);
sftp_msg_write_data(&buf2, &buflen2, id, id_len, TRUE);
sftp_msg_write_byte(&buf2, &buflen2, SFTP_SSH2_MSG_USER_AUTH_REQUEST);
sftp_msg_write_string(&buf2, &buflen2, orig_user);
if (sftp_interop_supports_feature(SFTP_SSH2_FEAT_SERVICE_IN_HOST_SIG)) {
sftp_msg_write_string(&buf2, &buflen2, service);
} else {
sftp_msg_write_string(&buf2, &buflen2, "ssh-userauth");
}
sftp_msg_write_string(&buf2, &buflen2, "hostbased");
sftp_msg_write_string(&buf2, &buflen2, hostkey_algo);
sftp_msg_write_data(&buf2, &buflen2, hostkey_data, hostkey_datalen, TRUE);
sftp_msg_write_string(&buf2, &buflen2, host_fqdn);
sftp_msg_write_string(&buf2, &buflen2, host_user_utf8);
if (sftp_keys_verify_signed_data(pkt->pool, hostkey_algo, hostkey_data,
hostkey_datalen, signature_data, signature_len, (unsigned char *) ptr2,
(bufsz2 - buflen2)) < 0) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"failed to verify '%s' signature on hostbased auth request for "
"user '%s', host %s", hostkey_algo, orig_user, host_fqdn);
*send_userauth_fail = TRUE;
return 0;
}
/* Make sure the user is authorized to login. Normally this is checked
* as part of the password verification process, but in the case of
* hostbased authentication, there is no password to verify.
*/
if (pr_auth_authorize(pkt->pool, user) != PR_AUTH_OK) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"authentication for user '%s' failed: User not authorized", user);
pr_log_auth(PR_LOG_NOTICE, "USER %s (Login failed): User not authorized "
"for login", user);
*send_userauth_fail = TRUE;
errno = EACCES;
return 0;
}
return 1;
}
int sftp_auth_publickey(struct ssh2_packet *pkt, cmd_rec *pass_cmd,
const char *orig_user, const char *user, const char *service, char **buf,
uint32_t *buflen, int *send_userauth_fail) {
int have_signature, pubkey_type;
char *pubkey_algo = NULL, *pubkey_data;
const char *fp = NULL;
uint32_t pubkey_len;
struct passwd *pw;
if (pr_cmd_dispatch_phase(pass_cmd, PRE_CMD, 0) < 0) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"authentication request for user '%s' blocked by '%s' handler",
orig_user, pass_cmd->argv[0]);
pr_cmd_dispatch_phase(pass_cmd, POST_CMD_ERR, 0);
pr_cmd_dispatch_phase(pass_cmd, LOG_CMD_ERR, 0);
*send_userauth_fail = TRUE;
errno = EPERM;
return 0;
}
have_signature = sftp_msg_read_bool(pkt->pool, buf, buflen);
if (sftp_interop_supports_feature(SFTP_SSH2_FEAT_HAVE_PUBKEY_ALGO)) {
pubkey_algo = sftp_msg_read_string(pkt->pool, buf, buflen);
}
pubkey_len = sftp_msg_read_int(pkt->pool, buf, buflen);
pubkey_data = sftp_msg_read_data(pkt->pool, buf, buflen, pubkey_len);
if (pubkey_algo == NULL) {
/* The client did not send the string identifying the public key algorithm.
* Thus we need to extract the algorithm string from the public key data.
*/
pubkey_algo = sftp_msg_read_string(pkt->pool, &pubkey_data, &pubkey_len);
}
pr_trace_msg(trace_channel, 9, "client sent '%s' public key %s",
pubkey_algo, have_signature ? "with signature" : "without signature");
if (strncmp(pubkey_algo, "ssh-rsa", 8) == 0) {
pubkey_type = EVP_PKEY_RSA;
} else if (strncmp(pubkey_algo, "ssh-dss", 8) == 0) {
pubkey_type = EVP_PKEY_DSA;
/* XXX This is where we would add support for X509 public keys, e.g.:
*
* x509v3-ssh-dss
* x509v3-ssh-rsa
* x509v3-sign (older)
*
*/
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"unsupported public key algorithm '%s' requested, rejecting request",
pubkey_algo);
*send_userauth_fail = TRUE;
errno = EINVAL;
return 0;
}
if (sftp_keys_verify_pubkey_type(pkt->pool, pubkey_data, pubkey_len,
pubkey_type) != TRUE) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"unable to verify that given public key matches given '%s' algorithm",
pubkey_algo);
*send_userauth_fail = TRUE;
errno = EINVAL;
return 0;
}
#ifdef OPENSSL_FIPS
if (FIPS_mode()) {
fp = sftp_keys_get_fingerprint(pkt->pool, pubkey_data, pubkey_len,
SFTP_KEYS_FP_DIGEST_SHA1);
if (fp != NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"public key SHA1 fingerprint: %s", fp);
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error obtaining public key SHA1 fingerprint: %s", strerror(errno));
}
} else {
#endif /* OPENSSL_FIPS */
fp = sftp_keys_get_fingerprint(pkt->pool, pubkey_data, pubkey_len,
SFTP_KEYS_FP_DIGEST_MD5);
if (fp != NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"public key MD5 fingerprint: %s", fp);
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error obtaining public key MD5 fingerprint: %s", strerror(errno));
}
#ifdef OPENSSL_FIPS
}
#endif /* OPENSSL_FIPS */
pw = pr_auth_getpwnam(pkt->pool, user);
if (pw == NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"no account for user '%s' found", user);
pr_log_auth(PR_LOG_NOTICE,
"USER %s: no such user found from %s [%s] to %s:%d", user,
session.c->remote_name, pr_netaddr_get_ipstr(session.c->remote_addr),
pr_netaddr_get_ipstr(session.c->local_addr), session.c->local_port);
*send_userauth_fail = TRUE;
errno = ENOENT;
return 0;
}
if (!have_signature) {
/* We don't perform the actual authentication just yet; we need to
* let the client know that the pubkey algorithms are acceptable.
*/
if (send_pubkey_ok(pubkey_algo, pubkey_data, pubkey_len) < 0) {
return -1;
}
return 0;
} else {
const unsigned char *id;
char *buf2, *ptr2, *signature_data;
uint32_t buflen2, bufsz2, id_len, signature_len;
/* XXX This should become a more generic "is this key data
* usable/acceptable?" check (and take the pubkey_type parameter), so that
* that is where we would check the validity/usability of an X509v3 cert
* (if a cert), or if the key is on the blacklist (if a key).
*/
if (sftp_blacklist_reject_key(pkt->pool, pubkey_data, pubkey_len)) {
*send_userauth_fail = TRUE;
errno = EPERM;
return 0;
}
signature_len = sftp_msg_read_int(pkt->pool, buf, buflen);
signature_data = sftp_msg_read_data(pkt->pool, buf, buflen, signature_len);
/* The client signed the request as well; we need to authenticate the
* user with the given pubkey now. If that succeeds, we use the
* signature to verify the request. And if that succeeds, then we're
* done authenticating.
*/
/* XXX Need to pass the pubkey_type here as well, so that the
* verification routines can handle different databases of keys/certs.
*
* For X509v3 certs, we will want a way to enforce/restrict which
* user names can be used with the provided cert. Perhaps a database
* mapping cert fingerprints to user names/UIDs? Configurable callback
* check (HOOK?), for modules to enforce.
*/
if (sftp_keystore_verify_user_key(pkt->pool, user, pubkey_data,
pubkey_len) < 0) {
*send_userauth_fail = TRUE;
return 0;
}
/* Make sure the signature matches as well. */
id_len = sftp_session_get_id(&id);
/* Make sure to allocate a buffer large enough to hold the publickey
* signature and data we want to send back.
*/
bufsz2 = buflen2 = pubkey_len + 1024;
ptr2 = buf2 = sftp_msg_getbuf(pkt->pool, bufsz2);
sftp_msg_write_data(&buf2, &buflen2, (char *) id, id_len, TRUE);
sftp_msg_write_byte(&buf2, &buflen2, SFTP_SSH2_MSG_USER_AUTH_REQUEST);
sftp_msg_write_string(&buf2, &buflen2, orig_user);
if (sftp_interop_supports_feature(SFTP_SSH2_FEAT_SERVICE_IN_PUBKEY_SIG)) {
sftp_msg_write_string(&buf2, &buflen2, service);
} else {
sftp_msg_write_string(&buf2, &buflen2, "ssh-userauth");
}
if (sftp_interop_supports_feature(SFTP_SSH2_FEAT_HAVE_PUBKEY_ALGO)) {
sftp_msg_write_string(&buf2, &buflen2, "publickey");
sftp_msg_write_bool(&buf2, &buflen2, TRUE);
sftp_msg_write_string(&buf2, &buflen2, pubkey_algo);
} else {
sftp_msg_write_bool(&buf2, &buflen2, TRUE);
}
sftp_msg_write_data(&buf2, &buflen2, pubkey_data, pubkey_len, TRUE);
if (sftp_keys_verify_signed_data(pkt->pool, pubkey_algo, pubkey_data,
pubkey_len, signature_data, signature_len, (unsigned char *) ptr2,
(bufsz2 - buflen2)) < 0) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"failed to verify '%s' signature on public key auth request for "
"user '%s'", pubkey_algo, orig_user);
*send_userauth_fail = TRUE;
return 0;
}
}
/* Make sure the user is authorized to login. Normally this is checked
* as part of the password verification process, but in the case of
* publickey authentication, there is no password to verify.
*/
if (pr_auth_authorize(pkt->pool, user) != PR_AUTH_OK) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"authentication for user '%s' failed: User not authorized", user);
pr_log_auth(PR_LOG_NOTICE, "USER %s (Login failed): User not authorized "
"for login", user);
*send_userauth_fail = TRUE;
errno = EACCES;
return 0;
}
return 1;
}
int sftp_mac_write_data(struct ssh2_packet *pkt) {
struct sftp_mac *mac;
HMAC_CTX *mac_ctx;
mac = &(write_macs[write_mac_idx]);
mac_ctx = &(write_ctxs[write_mac_idx]);
if (mac->key) {
unsigned char *mac_data;
char *buf, *ptr;
uint32_t buflen, bufsz = (sizeof(uint32_t) * 2) + pkt->packet_len,
mac_len = 0;
mac_data = pcalloc(pkt->pool, EVP_MAX_MD_SIZE);
buflen = bufsz;
ptr = buf = sftp_msg_getbuf(pkt->pool, bufsz);
sftp_msg_write_int(&buf, &buflen, pkt->seqno);
sftp_msg_write_int(&buf, &buflen, pkt->packet_len);
sftp_msg_write_byte(&buf, &buflen, pkt->padding_len);
sftp_msg_write_data(&buf, &buflen, pkt->payload, pkt->payload_len, FALSE);
sftp_msg_write_data(&buf, &buflen, pkt->padding, pkt->padding_len, FALSE);
#if OPENSSL_VERSION_NUMBER > 0x000907000L
# if OPENSSL_VERSION_NUMBER >= 0x10000001L
if (HMAC_Init_ex(mac_ctx, NULL, 0, NULL, NULL) != 1) {
pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error resetting HMAC context: %s", sftp_crypto_get_errors());
errno = EPERM;
return -1;
}
# else
HMAC_Init_ex(mac_ctx, NULL, 0, NULL, NULL);
# endif /* OpenSSL-1.0.0 and later */
#else
HMAC_Init(mac_ctx, NULL, 0, NULL);
#endif /* OpenSSL-0.9.7 and later */
#if OPENSSL_VERSION_NUMBER >= 0x10000001L
if (HMAC_Update(mac_ctx, (unsigned char *) ptr, (bufsz - buflen)) != 1) {
pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error adding %lu bytes of data to HMAC context: %s",
(unsigned long) (bufsz - buflen), sftp_crypto_get_errors());
errno = EPERM;
return -1;
}
if (HMAC_Final(mac_ctx, mac_data, &mac_len) != 1) {
pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error finalizing HMAC context: %s", sftp_crypto_get_errors());
errno = EPERM;
return -1;
}
#else
HMAC_Update(mac_ctx, (unsigned char *) ptr, (bufsz - buflen));
HMAC_Final(mac_ctx, mac_data, &mac_len);
#endif /* OpenSSL-1.0.0 and later */
if (mac_len == 0) {
pkt->mac = NULL;
pkt->mac_len = 0;
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error computing MAC using %s: %s", mac->algo,
sftp_crypto_get_errors());
return -1;
}
if (mac->mac_len != 0) {
mac_len = mac->mac_len;
}
pkt->mac_len = mac_len;
pkt->mac = pcalloc(pkt->pool, pkt->mac_len);
memcpy(pkt->mac, mac_data, mac_len);
#ifdef SFTP_DEBUG_PACKET
{
unsigned int i;
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"server MAC (len %lu, seqno %lu):",
(unsigned long) pkt->mac_len, (unsigned long) pkt->seqno);
for (i = 0; i < mac_len;) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
" %02x%02x %02x%02x %02x%02x %02x%02x",
((unsigned char *) pkt->mac)[i], ((unsigned char *) pkt->mac)[i+1],
((unsigned char *) pkt->mac)[i+2], ((unsigned char *) pkt->mac)[i+3],
((unsigned char *) pkt->mac)[i+4], ((unsigned char *) pkt->mac)[i+5],
((unsigned char *) pkt->mac)[i+6], ((unsigned char *) pkt->mac)[i+7]);
i += 8;
}
}
#endif
return 0;
}
pkt->mac = NULL;
pkt->mac_len = 0;
return 0;
}
int sftp_cipher_set_write_key(pool *p, const EVP_MD *hash, const BIGNUM *k,
const char *h, uint32_t hlen) {
const unsigned char *id = NULL;
unsigned char *buf, *ptr;
char letter;
uint32_t buflen, bufsz, id_len;
int key_len;
struct sftp_cipher *cipher;
EVP_CIPHER_CTX *cipher_ctx;
switch_write_cipher();
cipher = &(write_ciphers[write_cipher_idx]);
cipher_ctx = write_ctxs[write_cipher_idx];
/* XXX EVP_CIPHER_CTX_init() first appeared in OpenSSL 0.9.7. What to do
* for older OpenSSL installations?
*/
EVP_CIPHER_CTX_init(cipher_ctx);
bufsz = buflen = SFTP_CIPHER_BUFSZ;
ptr = buf = sftp_msg_getbuf(p, bufsz);
/* Need to use SSH2-style format of K for the IV and key. */
sftp_msg_write_mpint(&buf, &buflen, k);
id_len = sftp_session_get_id(&id);
/* IV: HASH(K || H || "B" || session_id) */
letter = 'B';
if (set_cipher_iv(cipher, hash, ptr, (bufsz - buflen), h, hlen, &letter, id,
id_len) < 0) {
pr_memscrub(ptr, bufsz);
return -1;
}
key_len = (int) cipher->key_len;
/* Key: HASH(K || H || "D" || session_id) */
letter = 'D';
if (set_cipher_key(cipher, hash, ptr, (bufsz - buflen), h, hlen, &letter,
id, id_len) < 0) {
pr_memscrub(ptr, bufsz);
return -1;
}
if (EVP_CipherInit(cipher_ctx, cipher->cipher, cipher->key,
cipher->iv, 1) != 1) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error initializing %s cipher for encryption: %s", cipher->algo,
sftp_crypto_get_errors());
pr_memscrub(ptr, bufsz);
return -1;
}
if (key_len > 0) {
/* Next, set the key length. */
if (EVP_CIPHER_CTX_set_key_length(cipher_ctx, key_len) != 1) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error setting key length (%d bytes) for %s cipher for decryption: %s",
key_len, cipher->algo, sftp_crypto_get_errors());
pr_memscrub(ptr, bufsz);
return -1;
}
}
if (set_cipher_discarded(cipher, cipher_ctx) < 0) {
pr_memscrub(ptr, bufsz);
return -1;
}
pr_memscrub(ptr, bufsz);
return 0;
}
