/**
* Handle received frame from broker.
*/
static int rd_kafka_sasl_handle_recv (rd_kafka_transport_t *rktrans,
rd_kafka_buf_t *rkbuf,
char *errstr, int errstr_size) {
int r;
rd_rkb_dbg(rktrans->rktrans_rkb, SECURITY, "SASL",
"Received SASL frame from broker (%"PRIdsz" bytes)",
rkbuf ? rkbuf->rkbuf_len : 0);
if (rktrans->rktrans_sasl.complete && (!rkbuf || rkbuf->rkbuf_len == 0))
goto auth_successful;
do {
sasl_interact_t *interact = NULL;
const char *out;
unsigned int outlen;
r = sasl_client_step(rktrans->rktrans_sasl.conn,
rkbuf && rkbuf->rkbuf_len > 0 ?
rkbuf->rkbuf_rbuf : NULL,
rkbuf ? rkbuf->rkbuf_len : 0,
&interact,
&out, &outlen);
if (rkbuf) {
rd_kafka_buf_destroy(rkbuf);
rkbuf = NULL;
}
if (r >= 0) {
/* Note: outlen may be 0 here for an empty response */
if (rd_kafka_sasl_send(rktrans, out, outlen,
errstr, errstr_size) == -1)
return -1;
}
if (r == SASL_INTERACT)
rd_rkb_dbg(rktrans->rktrans_rkb, SECURITY, "SASL",
"SASL_INTERACT: %lu %s, %s, %s, %p",
interact->id,
interact->challenge,
interact->prompt,
interact->defresult,
interact->result);
} while (r == SASL_INTERACT);
if (r == SASL_CONTINUE)
return 0; /* Wait for more data from broker */
else if (r != SASL_OK) {
rd_snprintf(errstr, errstr_size,
"SASL handshake failed (step): %s",
sasl_errdetail(rktrans->rktrans_sasl.conn));
return -1;
}
/* Authentication successful */
auth_successful:
if (rktrans->rktrans_rkb->rkb_rk->rk_conf.debug &
RD_KAFKA_DBG_SECURITY) {
const char *user, *mech, *authsrc;
if (sasl_getprop(rktrans->rktrans_sasl.conn, SASL_USERNAME,
(const void **)&user) != SASL_OK)
user = "******";
if (sasl_getprop(rktrans->rktrans_sasl.conn, SASL_MECHNAME,
(const void **)&mech) != SASL_OK)
mech = "(unknown)";
if (sasl_getprop(rktrans->rktrans_sasl.conn, SASL_AUTHSOURCE,
(const void **)&authsrc) != SASL_OK)
authsrc = "(unknown)";
rd_rkb_dbg(rktrans->rktrans_rkb, SECURITY, "SASL",
"Authenticated as %s using %s (%s)",
user, mech, authsrc);
}
rd_kafka_broker_connect_up(rktrans->rktrans_rkb);
return 0;
}
/**
* Initialize and start SASL authentication.
*
* Returns 0 on successful init and -1 on error.
*
* Locality: broker thread
*/
int rd_kafka_sasl_client_new (rd_kafka_transport_t *rktrans,
char *errstr, int errstr_size) {
int r;
rd_kafka_broker_t *rkb = rktrans->rktrans_rkb;
rd_kafka_t *rk = rkb->rkb_rk;
char *hostname, *t;
sasl_callback_t callbacks[16] = {
// { SASL_CB_GETOPT, (void *)rd_kafka_sasl_cb_getopt, rktrans },
{ SASL_CB_LOG, (void *)rd_kafka_sasl_cb_log, rktrans },
{ SASL_CB_AUTHNAME, (void *)rd_kafka_sasl_cb_getsimple, rktrans },
{ SASL_CB_PASS, (void *)rd_kafka_sasl_cb_getsecret, rktrans },
{ SASL_CB_ECHOPROMPT, (void *)rd_kafka_sasl_cb_chalprompt, rktrans },
{ SASL_CB_GETREALM, (void *)rd_kafka_sasl_cb_getrealm, rktrans },
{ SASL_CB_CANON_USER, (void *)rd_kafka_sasl_cb_canon, rktrans },
{ SASL_CB_LIST_END }
};
/* SASL_CB_USER is needed for PLAIN but breaks GSSAPI */
if (!strcmp(rk->rk_conf.sasl.service_name, "PLAIN")) {
int endidx;
/* Find end of callbacks array */
for (endidx = 0 ;
callbacks[endidx].id != SASL_CB_LIST_END ; endidx++)
;
callbacks[endidx].id = SASL_CB_USER;
callbacks[endidx].proc = (void *)rd_kafka_sasl_cb_getsimple;
endidx++;
callbacks[endidx].id = SASL_CB_LIST_END;
}
rd_strdupa(&hostname, rktrans->rktrans_rkb->rkb_nodename);
if ((t = strchr(hostname, ':')))
*t = '\0'; /* remove ":port" */
rd_rkb_dbg(rkb, SECURITY, "SASL",
"Initializing SASL client: service name %s, "
"hostname %s, mechanisms %s",
rk->rk_conf.sasl.service_name, hostname,
rk->rk_conf.sasl.mechanisms);
/* Acquire or refresh ticket if kinit is configured */
rd_kafka_sasl_kinit_refresh(rkb);
r = sasl_client_new(rk->rk_conf.sasl.service_name, hostname,
NULL, NULL, /* no local & remote IP checks */
callbacks, 0, &rktrans->rktrans_sasl.conn);
if (r != SASL_OK) {
rd_snprintf(errstr, errstr_size, "%s",
sasl_errstring(r, NULL, NULL));
return -1;
}
if (rk->rk_conf.debug & RD_KAFKA_DBG_SECURITY) {
const char *avail_mechs;
sasl_listmech(rktrans->rktrans_sasl.conn, NULL, NULL, " ", NULL,
&avail_mechs, NULL, NULL);
rd_rkb_dbg(rkb, SECURITY, "SASL",
"My supported SASL mechanisms: %s", avail_mechs);
}
rd_kafka_transport_poll_set(rktrans, POLLIN);
do {
const char *out;
unsigned int outlen;
const char *mech = NULL;
r = sasl_client_start(rktrans->rktrans_sasl.conn,
rk->rk_conf.sasl.mechanisms,
NULL, &out, &outlen, &mech);
if (r >= 0)
if (rd_kafka_sasl_send(rktrans, out, outlen,
errstr, errstr_size))
return -1;
} while (r == SASL_INTERACT);
if (r == SASL_OK) {
/* PLAIN is appearantly done here, but we still need to make sure
* the PLAIN frame is sent and we get a response back (but we must
* not pass the response to libsasl or it will fail). */
rktrans->rktrans_sasl.complete = 1;
return 0;
} else if (r != SASL_CONTINUE) {
rd_snprintf(errstr, errstr_size,
"SASL handshake failed (start (%d)): %s",
r, sasl_errdetail(rktrans->rktrans_sasl.conn));
return -1;
}
return 0;
}
/**
* @brief Build client-final-message
* @returns -1 on error.
*/
static int
rd_kafka_sasl_scram_build_client_final_message (
rd_kafka_transport_t *rktrans,
const rd_chariov_t *salt,
const char *server_nonce,
const rd_chariov_t *server_first_msg,
int itcnt, rd_chariov_t *out) {
struct rd_kafka_sasl_scram_state *state = rktrans->rktrans_sasl.state;
const rd_kafka_conf_t *conf = &rktrans->rktrans_rkb->rkb_rk->rk_conf;
rd_chariov_t SaslPassword =
{ .ptr = conf->sasl.password,
.size = strlen(conf->sasl.password) };
rd_chariov_t SaltedPassword =
{ .ptr = rd_alloca(EVP_MAX_MD_SIZE) };
rd_chariov_t ClientKey =
{ .ptr = rd_alloca(EVP_MAX_MD_SIZE) };
rd_chariov_t ServerKey =
{ .ptr = rd_alloca(EVP_MAX_MD_SIZE) };
rd_chariov_t StoredKey =
{ .ptr = rd_alloca(EVP_MAX_MD_SIZE) };
rd_chariov_t AuthMessage = RD_ZERO_INIT;
rd_chariov_t ClientSignature =
{ .ptr = rd_alloca(EVP_MAX_MD_SIZE) };
rd_chariov_t ServerSignature =
{ .ptr = rd_alloca(EVP_MAX_MD_SIZE) };
const rd_chariov_t ClientKeyVerbatim =
{ .ptr = "Client Key", .size = 10 };
const rd_chariov_t ServerKeyVerbatim =
{ .ptr = "Server Key", .size = 10 };
rd_chariov_t ClientProof =
{ .ptr = rd_alloca(EVP_MAX_MD_SIZE) };
rd_chariov_t client_final_msg_wo_proof;
char *ClientProofB64;
int i;
/* Constructing the ClientProof attribute (p):
*
* p = Base64-encoded ClientProof
* SaltedPassword := Hi(Normalize(password), salt, i)
* ClientKey := HMAC(SaltedPassword, "Client Key")
* StoredKey := H(ClientKey)
* AuthMessage := client-first-message-bare + "," +
* server-first-message + "," +
* client-final-message-without-proof
* ClientSignature := HMAC(StoredKey, AuthMessage)
* ClientProof := ClientKey XOR ClientSignature
* ServerKey := HMAC(SaltedPassword, "Server Key")
* ServerSignature := HMAC(ServerKey, AuthMessage)
*/
/* SaltedPassword := Hi(Normalize(password), salt, i) */
if (rd_kafka_sasl_scram_Hi(
rktrans, &SaslPassword, salt,
itcnt, &SaltedPassword) == -1)
return -1;
/* ClientKey := HMAC(SaltedPassword, "Client Key") */
if (rd_kafka_sasl_scram_HMAC(
rktrans, &SaltedPassword, &ClientKeyVerbatim,
&ClientKey) == -1)
return -1;
/* StoredKey := H(ClientKey) */
if (rd_kafka_sasl_scram_H(rktrans, &ClientKey, &StoredKey) == -1)
return -1;
/* client-final-message-without-proof */
rd_kafka_sasl_scram_build_client_final_message_wo_proof(
state, server_nonce, &client_final_msg_wo_proof);
/* AuthMessage := client-first-message-bare + "," +
* server-first-message + "," +
* client-final-message-without-proof */
AuthMessage.size =
state->first_msg_bare.size + 1 +
server_first_msg->size + 1 +
client_final_msg_wo_proof.size;
AuthMessage.ptr = rd_alloca(AuthMessage.size+1);
rd_snprintf(AuthMessage.ptr, AuthMessage.size+1,
"%.*s,%.*s,%.*s",
(int)state->first_msg_bare.size, state->first_msg_bare.ptr,
(int)server_first_msg->size, server_first_msg->ptr,
(int)client_final_msg_wo_proof.size,
client_final_msg_wo_proof.ptr);
/*
* Calculate ServerSignature for later verification when
* server-final-message is received.
*/
/* ServerKey := HMAC(SaltedPassword, "Server Key") */
if (rd_kafka_sasl_scram_HMAC(
rktrans, &SaltedPassword, &ServerKeyVerbatim,
&ServerKey) == -1) {
rd_free(client_final_msg_wo_proof.ptr);
return -1;
}
/* ServerSignature := HMAC(ServerKey, AuthMessage) */
if (rd_kafka_sasl_scram_HMAC(rktrans, &ServerKey,
&AuthMessage, &ServerSignature) == -1) {
rd_free(client_final_msg_wo_proof.ptr);
return -1;
}
/* Store the Base64 encoded ServerSignature for quick comparison */
state->ServerSignatureB64 = rd_base64_encode(&ServerSignature);
/*
* Continue with client-final-message
*/
/* ClientSignature := HMAC(StoredKey, AuthMessage) */
if (rd_kafka_sasl_scram_HMAC(rktrans, &StoredKey,
&AuthMessage, &ClientSignature) == -1) {
rd_free(client_final_msg_wo_proof.ptr);
return -1;
}
/* ClientProof := ClientKey XOR ClientSignature */
assert(ClientKey.size == ClientSignature.size);
for (i = 0 ; i < (int)ClientKey.size ; i++)
ClientProof.ptr[i] = ClientKey.ptr[i] ^ ClientSignature.ptr[i];
ClientProof.size = ClientKey.size;
/* Base64 encoded ClientProof */
ClientProofB64 = rd_base64_encode(&ClientProof);
/* Construct client-final-message */
out->size = client_final_msg_wo_proof.size +
strlen(",p=") + strlen(ClientProofB64);
out->ptr = rd_malloc(out->size + 1);
rd_snprintf(out->ptr, out->size+1,
"%.*s,p=%s",
(int)client_final_msg_wo_proof.size,
client_final_msg_wo_proof.ptr,
ClientProofB64);
rd_free(ClientProofB64);
rd_free(client_final_msg_wo_proof.ptr);
return 0;
}
/**
* @brief Handle first message from server
*
* Parse server response which looks something like:
* "r=fyko+d2lbbFgONR....,s=QSXCR+Q6sek8bf92,i=4096"
*
* @returns -1 on error.
*/
static int
rd_kafka_sasl_scram_handle_server_first_message (rd_kafka_transport_t *rktrans,
const rd_chariov_t *in,
rd_chariov_t *out,
char *errstr,
size_t errstr_size) {
struct rd_kafka_sasl_scram_state *state = rktrans->rktrans_sasl.state;
char *server_nonce;
rd_chariov_t salt_b64, salt;
char *itcntstr;
const char *endptr;
int itcnt;
char *attr_m;
/* Mandatory future extension check */
if ((attr_m = rd_kafka_sasl_scram_get_attr(
in, 'm', NULL, NULL, 0))) {
rd_snprintf(errstr, errstr_size,
"Unsupported mandatory SCRAM extension");
rd_free(attr_m);
return -1;
}
/* Server nonce */
if (!(server_nonce = rd_kafka_sasl_scram_get_attr(
in, 'r',
"Server nonce in server-first-message",
errstr, errstr_size)))
return -1;
if (strlen(server_nonce) <= state->cnonce.size ||
strncmp(state->cnonce.ptr, server_nonce, state->cnonce.size)) {
rd_snprintf(errstr, errstr_size,
"Server/client nonce mismatch in "
"server-first-message");
rd_free(server_nonce);
return -1;
}
/* Salt (Base64) */
if (!(salt_b64.ptr = rd_kafka_sasl_scram_get_attr(
in, 's',
"Salt in server-first-message",
errstr, errstr_size))) {
rd_free(server_nonce);
return -1;
}
salt_b64.size = strlen(salt_b64.ptr);
/* Convert Salt to binary */
if (rd_base64_decode(&salt_b64, &salt) == -1) {
rd_snprintf(errstr, errstr_size,
"Invalid Base64 Salt in server-first-message");
rd_free(server_nonce);
rd_free(salt_b64.ptr);
}
rd_free(salt_b64.ptr);
/* Iteration count (as string) */
if (!(itcntstr = rd_kafka_sasl_scram_get_attr(
in, 'i',
"Iteration count in server-first-message",
errstr, errstr_size))) {
rd_free(server_nonce);
rd_free(salt.ptr);
return -1;
}
/* Iteration count (as int) */
errno = 0;
itcnt = (int)strtoul(itcntstr, (char **)&endptr, 10);
if (itcntstr == endptr || *endptr != '\0' || errno != 0 ||
itcnt > 1000000) {
rd_snprintf(errstr, errstr_size,
"Invalid value (not integer or too large) "
"for Iteration count in server-first-message");
rd_free(server_nonce);
rd_free(salt.ptr);
rd_free(itcntstr);
return -1;
}
rd_free(itcntstr);
/* Build client-final-message */
if (rd_kafka_sasl_scram_build_client_final_message(
rktrans, &salt, server_nonce, in, itcnt, out) == -1) {
rd_snprintf(errstr, errstr_size,
"Failed to build SCRAM client-final-message");
rd_free(salt.ptr);
rd_free(server_nonce);
return -1;
}
rd_free(server_nonce);
rd_free(salt.ptr);
return 0;
}
/**
* @brief Handle server-final-message
*
* This is the end of authentication and the SCRAM state
* will be freed at the end of this function regardless of
* authentication outcome.
*
* @returns -1 on failure
*/
static int
rd_kafka_sasl_scram_handle_server_final_message (
rd_kafka_transport_t *rktrans,
const rd_chariov_t *in,
char *errstr, size_t errstr_size) {
struct rd_kafka_sasl_scram_state *state = rktrans->rktrans_sasl.state;
char *attr_v, *attr_e;
if ((attr_e = rd_kafka_sasl_scram_get_attr(
in, 'e', "server-error in server-final-message",
errstr, errstr_size))) {
/* Authentication failed */
rd_snprintf(errstr, errstr_size,
"SASL SCRAM authentication failed: "
"broker responded with %s",
attr_e);
rd_free(attr_e);
return -1;
} else if ((attr_v = rd_kafka_sasl_scram_get_attr(
in, 'v', "verifier in server-final-message",
errstr, errstr_size))) {
const rd_kafka_conf_t *conf;
/* Authentication succesful on server,
* but we need to verify the ServerSignature too. */
rd_rkb_dbg(rktrans->rktrans_rkb, SECURITY | RD_KAFKA_DBG_BROKER,
"SCRAMAUTH",
"SASL SCRAM authentication succesful on server: "
"verifying ServerSignature");
if (strcmp(attr_v, state->ServerSignatureB64)) {
rd_snprintf(errstr, errstr_size,
"SASL SCRAM authentication failed: "
"ServerSignature mismatch "
"(server's %s != ours %s)",
attr_v, state->ServerSignatureB64);
rd_free(attr_v);
return -1;
}
rd_free(attr_v);
conf = &rktrans->rktrans_rkb->rkb_rk->rk_conf;
rd_rkb_dbg(rktrans->rktrans_rkb, SECURITY | RD_KAFKA_DBG_BROKER,
"SCRAMAUTH",
"Authenticated as %s using %s",
conf->sasl.username,
conf->sasl.mechanisms);
rd_kafka_sasl_auth_done(rktrans);
return 0;
} else {
rd_snprintf(errstr, errstr_size,
"SASL SCRAM authentication failed: "
"no verifier or server-error returned from broker");
return -1;
}
}
/**
* @brief Build client-first-message
*/
static void
rd_kafka_sasl_scram_build_client_first_message (
rd_kafka_transport_t *rktrans,
rd_chariov_t *out) {
char *sasl_username;
struct rd_kafka_sasl_scram_state *state = rktrans->rktrans_sasl.state;
const rd_kafka_conf_t *conf = &rktrans->rktrans_rkb->rkb_rk->rk_conf;
rd_kafka_sasl_scram_generate_nonce(&state->cnonce);
sasl_username = rd_kafka_sasl_safe_string(conf->sasl.username);
out->size = strlen("n,,n=,r=") + strlen(sasl_username) +
state->cnonce.size;
out->ptr = rd_malloc(out->size+1);
rd_snprintf(out->ptr, out->size+1,
"n,,n=%s,r=%.*s",
sasl_username,
(int)state->cnonce.size, state->cnonce.ptr);
rd_free(sasl_username);
/* Save client-first-message-bare (skip gs2-header) */
state->first_msg_bare.size = out->size-3;
state->first_msg_bare.ptr = rd_memdup(out->ptr+3,
state->first_msg_bare.size);
}
/**
* @brief SASL SCRAM client state machine
* @returns -1 on failure (errstr set), else 0.
*/
static int rd_kafka_sasl_scram_fsm (rd_kafka_transport_t *rktrans,
const rd_chariov_t *in,
char *errstr, size_t errstr_size) {
static const char *state_names[] = {
"client-first-message",
"server-first-message",
"client-final-message",
};
struct rd_kafka_sasl_scram_state *state = rktrans->rktrans_sasl.state;
rd_chariov_t out = RD_ZERO_INIT;
int r = -1;
rd_ts_t ts_start = rd_clock();
int prev_state = state->state;
rd_rkb_dbg(rktrans->rktrans_rkb, SECURITY, "SASLSCRAM",
"SASL SCRAM client in state %s",
state_names[state->state]);
switch (state->state)
{
case RD_KAFKA_SASL_SCRAM_STATE_CLIENT_FIRST_MESSAGE:
rd_dassert(!in); /* Not expecting any server-input */
rd_kafka_sasl_scram_build_client_first_message(rktrans, &out);
state->state = RD_KAFKA_SASL_SCRAM_STATE_SERVER_FIRST_MESSAGE;
break;
case RD_KAFKA_SASL_SCRAM_STATE_SERVER_FIRST_MESSAGE:
rd_dassert(in); /* Requires server-input */
if (rd_kafka_sasl_scram_handle_server_first_message(
rktrans, in, &out, errstr, errstr_size) == -1)
return -1;
state->state = RD_KAFKA_SASL_SCRAM_STATE_CLIENT_FINAL_MESSAGE;
break;
case RD_KAFKA_SASL_SCRAM_STATE_CLIENT_FINAL_MESSAGE:
rd_dassert(in); /* Requires server-input */
r = rd_kafka_sasl_scram_handle_server_final_message(
rktrans, in, errstr, errstr_size);
break;
}
if (out.ptr) {
r = rd_kafka_sasl_send(rktrans, out.ptr, (int)out.size,
errstr, errstr_size);
rd_free(out.ptr);
}
ts_start = (rd_clock() - ts_start) / 1000;
if (ts_start >= 100)
rd_rkb_dbg(rktrans->rktrans_rkb, SECURITY, "SCRAM",
"SASL SCRAM state %s handled in %"PRId64"ms",
state_names[prev_state], ts_start);
return r;
}
/**
* @brief Handle received frame from broker.
*/
static int rd_kafka_sasl_scram_recv (rd_kafka_transport_t *rktrans,
const void *buf, size_t size,
char *errstr, size_t errstr_size) {
const rd_chariov_t in = { .ptr = (char *)buf, .size = size };
return rd_kafka_sasl_scram_fsm(rktrans, &in, errstr, errstr_size);
}
/**
* @brief Initialize and start SASL SCRAM (builtin) authentication.
*
* Returns 0 on successful init and -1 on error.
*
* @locality broker thread
*/
static int rd_kafka_sasl_scram_client_new (rd_kafka_transport_t *rktrans,
const char *hostname,
char *errstr, size_t errstr_size) {
struct rd_kafka_sasl_scram_state *state;
state = rd_calloc(1, sizeof(*state));
state->state = RD_KAFKA_SASL_SCRAM_STATE_CLIENT_FIRST_MESSAGE;
rktrans->rktrans_sasl.state = state;
/* Kick off the FSM */
return rd_kafka_sasl_scram_fsm(rktrans, NULL, errstr, errstr_size);
}
/**
* @brief Validate SCRAM config and look up the hash function
*/
static int rd_kafka_sasl_scram_conf_validate (rd_kafka_t *rk,
char *errstr,
size_t errstr_size) {
const char *mech = rk->rk_conf.sasl.mechanisms;
if (!rk->rk_conf.sasl.username || !rk->rk_conf.sasl.password) {
rd_snprintf(errstr, errstr_size,
"sasl.username and sasl.password must be set");
return -1;
}
if (!strcmp(mech, "SCRAM-SHA-1")) {
rk->rk_conf.sasl.scram_evp = EVP_sha1();
rk->rk_conf.sasl.scram_H = SHA1;
rk->rk_conf.sasl.scram_H_size = SHA_DIGEST_LENGTH;
} else if (!strcmp(mech, "SCRAM-SHA-256")) {
rk->rk_conf.sasl.scram_evp = EVP_sha256();
rk->rk_conf.sasl.scram_H = SHA256;
rk->rk_conf.sasl.scram_H_size = SHA256_DIGEST_LENGTH;
} else if (!strcmp(mech, "SCRAM-SHA-512")) {
rk->rk_conf.sasl.scram_evp = EVP_sha512();
rk->rk_conf.sasl.scram_H = SHA512;
rk->rk_conf.sasl.scram_H_size = SHA512_DIGEST_LENGTH;
} else {
rd_snprintf(errstr, errstr_size,
"Unsupported hash function: %s "
"(try SCRAM-SHA-512)",
mech);
return -1;
}
return 0;
}
const struct rd_kafka_sasl_provider rd_kafka_sasl_scram_provider = {
.name = "SCRAM (builtin)",
.client_new = rd_kafka_sasl_scram_client_new,
.recv = rd_kafka_sasl_scram_recv,
.close = rd_kafka_sasl_scram_close,
.conf_validate = rd_kafka_sasl_scram_conf_validate,
};
