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Support channel binding 'tls-unique' in SCRAM

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This is the basic feature set using OpenSSL to support the feature.  In
order to allow the frontend and the backend to fetch the sent and
expected TLS Finished messages, a PG-like API is added to be able to
make the interface pluggable for other SSL implementations.

This commit also adds a infrastructure to facilitate the addition of
future channel binding types as well as libpq parameters to control the
SASL mechanism names and channel binding names.  Those will be added by
upcoming commits.

Some tests are added to the SSL test suite to test SCRAM authentication
with channel binding.

Author: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
This commit is contained in:
Peter Eisentraut 2017-11-18 10:07:57 -05:00
parent 611fe7d479
commit 9288d62bb4
14 changed files with 557 additions and 114 deletions
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31
doc/src/sgml/protocol.sgml
View File

@ -1461,10 +1461,11 @@ SELCT 1/0;
<para>
<firstterm>SASL</firstterm> is a framework for authentication in connection-oriented
protocols. At the moment, <productname>PostgreSQL</productname> implements only one SASL
authentication mechanism, SCRAM-SHA-256, but more might be added in the
future. The below steps illustrate how SASL authentication is performed in
general, while the next subsection gives more details on SCRAM-SHA-256.
protocols. At the moment, <productname>PostgreSQL</productname> implements two SASL
authentication mechanisms, SCRAM-SHA-256 and SCRAM-SHA-256-PLUS. More
might be added in the future. The below steps illustrate how SASL
authentication is performed in general, while the next subsection gives
more details on SCRAM-SHA-256 and SCRAM-SHA-256-PLUS.
</para>
<procedure>
@ -1518,9 +1519,10 @@ ErrorMessage.
<title>SCRAM-SHA-256 authentication</title>
<para>
<firstterm>SCRAM-SHA-256</firstterm> (called just <firstterm>SCRAM</firstterm> from now on) is
the only implemented SASL mechanism, at the moment. It is described in detail
in RFC 7677 and RFC 5802.
The implemented SASL mechanisms at the moment
are <literal>SCRAM-SHA-256</literal> and its variant with channel
binding <literal>SCRAM-SHA-256-PLUS</literal>. They are described in
detail in RFC 7677 and RFC 5802.
</para>
<para>
@ -1547,7 +1549,10 @@ the password is in.
</para>
<para>
<firstterm>Channel binding</firstterm> has not been implemented yet.
<firstterm>Channel binding</firstterm> is supported in PostgreSQL builds with
SSL support. The SASL mechanism name for SCRAM with channel binding
is <literal>SCRAM-SHA-256-PLUS</literal>. The only channel binding type
supported at the moment is <literal>tls-unique</literal>, defined in RFC 5929.
</para>
<procedure>
@ -1556,13 +1561,19 @@ the password is in.
<para>
The server sends an AuthenticationSASL message. It includes a list of
SASL authentication mechanisms that the server can accept.
This will be <literal>SCRAM-SHA-256-PLUS</literal>
and <literal>SCRAM-SHA-256</literal> if the server is built with SSL
support, or else just the latter.
</para>
</step>
<step id="scram-client-first">
<para>
The client responds by sending a SASLInitialResponse message, which
indicates the chosen mechanism, <literal>SCRAM-SHA-256</literal>. In the Initial
Client response field, the message contains the SCRAM
indicates the chosen mechanism, <literal>SCRAM-SHA-256</literal> or
<literal>SCRAM-SHA-256-PLUS</literal>. (A client is free to choose either
mechanism, but for better security it should choose the channel-binding
variant if it can support it.) In the Initial Client response field,
the message contains the SCRAM
<structname>client-first-message</structname>.
</para>
</step>

187
src/backend/libpq/auth-scram.c
View File

@ -17,8 +17,6 @@
* by the SASLprep profile, we skip the SASLprep pre-processing and use
* the raw bytes in calculating the hash.
*
* - Channel binding is not supported yet.
*
*
* The password stored in pg_authid consists of the iteration count, salt,
* StoredKey and ServerKey.
@ -112,6 +110,11 @@ typedef struct
const char *username; /* username from startup packet */
bool ssl_in_use;
const char *tls_finished_message;
size_t tls_finished_len;
char *channel_binding_type;
int iterations;
char *salt; /* base64-encoded */
uint8 StoredKey[SCRAM_KEY_LEN];
@ -168,7 +171,11 @@ static char *scram_mock_salt(const char *username);
* it will fail, as if an incorrect password was given.
*/
void *
pg_be_scram_init(const char *username, const char *shadow_pass)
pg_be_scram_init(const char *username,
const char *shadow_pass,
bool ssl_in_use,
const char *tls_finished_message,
size_t tls_finished_len)
{
scram_state *state;
bool got_verifier;
@ -176,6 +183,10 @@ pg_be_scram_init(const char *username, const char *shadow_pass)
state = (scram_state *) palloc0(sizeof(scram_state));
state->state = SCRAM_AUTH_INIT;
state->username = username;
state->ssl_in_use = ssl_in_use;
state->tls_finished_message = tls_finished_message;
state->tls_finished_len = tls_finished_len;
state->channel_binding_type = NULL;
/*
* Parse the stored password verifier.
@ -773,38 +784,18 @@ read_client_first_message(scram_state *state, char *input)
*------
*/
/* read gs2-cbind-flag */
/*
* Read gs2-cbind-flag. (For details see also RFC 5802 Section 6 "Channel
* Binding".)
*/
switch (*input)
{
case 'n':
/* Client does not support channel binding */
input++;
break;
case 'y':
/* Client supports channel binding, but we're not doing it today */
input++;
break;
case 'p':
/*
* Client requires channel binding. We don't support it.
*
* RFC 5802 specifies a particular error code,
* e=server-does-support-channel-binding, for this. But it can
* only be sent in the server-final message, and we don't want to
* go through the motions of the authentication, knowing it will
* fail, just to send that error message.
* The client does not support channel binding or has simply
* decided to not use it. In that case just let it go.
*/
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("client requires SCRAM channel binding, but it is not supported")));
default:
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("malformed SCRAM message"),
errdetail("Unexpected channel-binding flag \"%s\".",
sanitize_char(*input))));
}
input++;
if (*input != ',')
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
@ -812,6 +803,77 @@ read_client_first_message(scram_state *state, char *input)
errdetail("Comma expected, but found character \"%s\".",
sanitize_char(*input))));
input++;
break;
case 'y':
/*
* The client supports channel binding and thinks that the server
* does not. In this case, the server must fail authentication if
* it supports channel binding, which in this implementation is
* the case if a connection is using SSL.
*/
if (state->ssl_in_use)
ereport(ERROR,
(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
errmsg("SCRAM channel binding negotiation error"),
errdetail("The client supports SCRAM channel binding but thinks the server does not. "
"However, this server does support channel binding.")));
input++;
if (*input != ',')
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("malformed SCRAM message"),
errdetail("Comma expected, but found character \"%s\".",
sanitize_char(*input))));
input++;
break;
case 'p':
/*
* The client requires channel binding. Channel binding type
* follows, e.g., "p=tls-unique".
*/
{
char *channel_binding_type;
if (!state->ssl_in_use)
{
/*
* Without SSL, we don't support channel binding.
*
* RFC 5802 specifies a particular error code,
* e=server-does-support-channel-binding, for this. But
* it can only be sent in the server-final message, and we
* don't want to go through the motions of the
* authentication, knowing it will fail, just to send that
* error message.
*/
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("client requires SCRAM channel binding, but it is not supported")));
}
/*
* Read value provided by client; only tls-unique is supported
* for now. (It is not safe to print the name of an
* unsupported binding type in the error message. Pranksters
* could print arbitrary strings into the log that way.)
*/
channel_binding_type = read_attr_value(&input, 'p');
if (strcmp(channel_binding_type, SCRAM_CHANNEL_BINDING_TLS_UNIQUE) != 0)
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
(errmsg("unsupported SCRAM channel-binding type"))));
/* Save the name for handling of subsequent messages */
state->channel_binding_type = pstrdup(channel_binding_type);
}
break;
default:
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg("malformed SCRAM message"),
errdetail("Unexpected channel-binding flag \"%s\".",
sanitize_char(*input))));
}
/*
* Forbid optional authzid (authorization identity). We don't support it.
@ -1032,14 +1094,73 @@ read_client_final_message(scram_state *state, char *input)
*/
/*
* Read channel-binding. We don't support channel binding, so it's
* expected to always be "biws", which is "n,,", base64-encoded.
* Read channel binding. This repeats the channel-binding flags and is
* then followed by the actual binding data depending on the type.
*/
channel_binding = read_attr_value(&p, 'c');
if (strcmp(channel_binding, "biws") != 0)
if (state->channel_binding_type)
{
const char *cbind_data = NULL;
size_t cbind_data_len = 0;
size_t cbind_header_len;
char *cbind_input;
size_t cbind_input_len;
char *b64_message;
int b64_message_len;
/*
* Fetch data appropriate for channel binding type
*/
if (strcmp(state->channel_binding_type, SCRAM_CHANNEL_BINDING_TLS_UNIQUE) == 0)
{
cbind_data = state->tls_finished_message;
cbind_data_len = state->tls_finished_len;
}
else
{
/* should not happen */
elog(ERROR, "invalid channel binding type");
}
/* should not happen */
if (cbind_data == NULL || cbind_data_len == 0)
elog(ERROR, "empty channel binding data for channel binding type \"%s\"",
state->channel_binding_type);
cbind_header_len = 4 + strlen(state->channel_binding_type); /* p=type,, */
cbind_input_len = cbind_header_len + cbind_data_len;
cbind_input = palloc(cbind_input_len);
snprintf(cbind_input, cbind_input_len, "p=%s,,", state->channel_binding_type);
memcpy(cbind_input + cbind_header_len, cbind_data, cbind_data_len);
b64_message = palloc(pg_b64_enc_len(cbind_input_len) + 1);
b64_message_len = pg_b64_encode(cbind_input, cbind_input_len,
b64_message);
b64_message[b64_message_len] = '\0';
/*
* Compare the value sent by the client with the value expected by
* the server.
*/
if (strcmp(channel_binding, b64_message) != 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
(errmsg("SCRAM channel binding check failed"))));
}
else
{
/*
* If we are not using channel binding, the binding data is expected
* to always be "biws", which is "n,," base64-encoded, or "eSws",
* which is "y,,".
*/
if (strcmp(channel_binding, "biws") != 0 &&
strcmp(channel_binding, "eSws") != 0)
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
(errmsg("unexpected SCRAM channel-binding attribute in client-final-message"))));
}
state->client_final_nonce = read_attr_value(&p, 'r');
/* ignore optional extensions */

54
src/backend/libpq/auth.c
View File

@ -860,6 +860,8 @@ CheckMD5Auth(Port *port, char *shadow_pass, char **logdetail)
static int
CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
{
char *sasl_mechs;
char *p;
int mtype;
StringInfoData buf;
void *scram_opaq;
@ -869,6 +871,8 @@ CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
int inputlen;
int result;
bool initial;
char *tls_finished = NULL;
size_t tls_finished_len = 0;
/*
* SASL auth is not supported for protocol versions before 3, because it
@ -885,12 +889,39 @@ CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
/*
* Send the SASL authentication request to user. It includes the list of
* authentication mechanisms (which is trivial, because we only support
* SCRAM-SHA-256 at the moment). The extra "\0" is for an empty string to
* terminate the list.
* authentication mechanisms that are supported. The order of mechanisms
* is advertised in decreasing order of importance. So the
* channel-binding variants go first, if they are supported. Channel
* binding is only supported in SSL builds.
*/
sendAuthRequest(port, AUTH_REQ_SASL, SCRAM_SHA256_NAME "\0",
strlen(SCRAM_SHA256_NAME) + 2);
sasl_mechs = palloc(strlen(SCRAM_SHA256_PLUS_NAME) +
strlen(SCRAM_SHA256_NAME) + 3);
p = sasl_mechs;
if (port->ssl_in_use)
{
strcpy(p, SCRAM_SHA256_PLUS_NAME);
p += strlen(SCRAM_SHA256_PLUS_NAME) + 1;
}
strcpy(p, SCRAM_SHA256_NAME);
p += strlen(SCRAM_SHA256_NAME) + 1;
/* Put another '\0' to mark that list is finished. */
p[0] = '\0';
sendAuthRequest(port, AUTH_REQ_SASL, sasl_mechs, p - sasl_mechs + 1);
pfree(sasl_mechs);
#ifdef USE_SSL
/*
* Get data for channel binding.
*/
if (port->ssl_in_use)
{
tls_finished = be_tls_get_peer_finished(port, &tls_finished_len);
}
#endif
/*
* Initialize the status tracker for message exchanges.
@ -903,7 +934,11 @@ CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
* This is because we don't want to reveal to an attacker what usernames
* are valid, nor which users have a valid password.
*/
scram_opaq = pg_be_scram_init(port->user_name, shadow_pass);
scram_opaq = pg_be_scram_init(port->user_name,
shadow_pass,
port->ssl_in_use,
tls_finished,
tls_finished_len);
/*
* Loop through SASL message exchange. This exchange can consist of
@ -951,12 +986,9 @@ CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
{
const char *selected_mech;
/*
* We only support SCRAM-SHA-256 at the moment, so anything else
* is an error.
*/
selected_mech = pq_getmsgrawstring(&buf);
if (strcmp(selected_mech, SCRAM_SHA256_NAME) != 0)
if (strcmp(selected_mech, SCRAM_SHA256_NAME) != 0 &&
strcmp(selected_mech, SCRAM_SHA256_PLUS_NAME) != 0)
{
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),

24
src/backend/libpq/be-secure-openssl.c
View File

@ -1215,6 +1215,30 @@ be_tls_get_peerdn_name(Port *port, char *ptr, size_t len)
ptr[0] = '\0';
}
/*
* Routine to get the expected TLS Finished message information from the
* client, useful for authorization when doing channel binding.
*
* Result is a palloc'd copy of the TLS Finished message with its size.
*/
char *
be_tls_get_peer_finished(Port *port, size_t *len)
{
char dummy[1];
char *result;
/*
* OpenSSL does not offer an API to directly get the length of the
* expected TLS Finished message, so just do a dummy call to grab this
* information to allow caller to do an allocation with a correct size.
*/
*len = SSL_get_peer_finished(port->ssl, dummy, sizeof(dummy));
result = palloc(*len);
(void) SSL_get_peer_finished(port->ssl, result, *len);
return result;
}
/*
* Convert an X509 subject name to a cstring.
*

1
src/include/libpq/libpq-be.h
View File

@ -209,6 +209,7 @@ extern bool be_tls_get_compression(Port *port);
extern void be_tls_get_version(Port *port, char *ptr, size_t len);
extern void be_tls_get_cipher(Port *port, char *ptr, size_t len);
extern void be_tls_get_peerdn_name(Port *port, char *ptr, size_t len);
extern char *be_tls_get_peer_finished(Port *port, size_t *len);
#endif
extern ProtocolVersion FrontendProtocol;

10
src/include/libpq/scram.h
View File

@ -13,8 +13,12 @@
#ifndef PG_SCRAM_H
#define PG_SCRAM_H
/* Name of SCRAM-SHA-256 per IANA */
/* Name of SCRAM mechanisms per IANA */
#define SCRAM_SHA256_NAME "SCRAM-SHA-256"
#define SCRAM_SHA256_PLUS_NAME "SCRAM-SHA-256-PLUS" /* with channel binding */
/* Channel binding types */
#define SCRAM_CHANNEL_BINDING_TLS_UNIQUE "tls-unique"
/* Status codes for message exchange */
#define SASL_EXCHANGE_CONTINUE 0
@ -22,7 +26,9 @@
#define SASL_EXCHANGE_FAILURE 2
/* Routines dedicated to authentication */
extern void *pg_be_scram_init(const char *username, const char *shadow_pass);
extern void *pg_be_scram_init(const char *username, const char *shadow_pass,
bool ssl_in_use, const char *tls_finished_message,
size_t tls_finished_len);
extern int pg_be_scram_exchange(void *opaq, char *input, int inputlen,
char **output, int *outputlen, char **logdetail);

170
src/interfaces/libpq/fe-auth-scram.c
View File

@ -17,6 +17,7 @@
#include "common/base64.h"
#include "common/saslprep.h"
#include "common/scram-common.h"
#include "libpq/scram.h"
#include "fe-auth.h"
/* These are needed for getpid(), in the fallback implementation */
@ -44,6 +45,11 @@ typedef struct
/* These are supplied by the user */
const char *username;
char *password;
bool ssl_in_use;
char *tls_finished_message;
size_t tls_finished_len;
char *sasl_mechanism;
const char *channel_binding_type;
/* We construct these */
uint8 SaltedPassword[SCRAM_KEY_LEN];
@ -79,25 +85,50 @@ static bool pg_frontend_random(char *dst, int len);
/*
* Initialize SCRAM exchange status.
*
* The non-const char* arguments should be passed in malloc'ed. They will be
* freed by pg_fe_scram_free().
*/
void *
pg_fe_scram_init(const char *username, const char *password)
pg_fe_scram_init(const char *username,
const char *password,
bool ssl_in_use,
const char *sasl_mechanism,
char *tls_finished_message,
size_t tls_finished_len)
{
fe_scram_state *state;
char *prep_password;
pg_saslprep_rc rc;
Assert(sasl_mechanism != NULL);
state = (fe_scram_state *) malloc(sizeof(fe_scram_state));
if (!state)
return NULL;
memset(state, 0, sizeof(fe_scram_state));
state->state = FE_SCRAM_INIT;
state->username = username;
state->ssl_in_use = ssl_in_use;
state->tls_finished_message = tls_finished_message;
state->tls_finished_len = tls_finished_len;
state->sasl_mechanism = strdup(sasl_mechanism);
if (!state->sasl_mechanism)
{
free(state);
return NULL;
}
/*
* Store channel binding type. Only one type is currently supported.
*/
state->channel_binding_type = SCRAM_CHANNEL_BINDING_TLS_UNIQUE;
/* Normalize the password with SASLprep, if possible */
rc = pg_saslprep(password, &prep_password);
if (rc == SASLPREP_OOM)
{
free(state->sasl_mechanism);
free(state);
return NULL;
}
@ -106,6 +137,7 @@ pg_fe_scram_init(const char *username, const char *password)
prep_password = strdup(password);
if (!prep_password)
{
free(state->sasl_mechanism);
free(state);
return NULL;
}
@ -125,6 +157,10 @@ pg_fe_scram_free(void *opaq)
if (state->password)
free(state->password);
if (state->tls_finished_message)
free(state->tls_finished_message);
if (state->sasl_mechanism)
free(state->sasl_mechanism);
/* client messages */
if (state->client_nonce)
@ -297,9 +333,10 @@ static char *
build_client_first_message(fe_scram_state *state, PQExpBuffer errormessage)
{
char raw_nonce[SCRAM_RAW_NONCE_LEN + 1];
char *buf;
char buflen;
char *result;
int channel_info_len;
int encoded_len;
PQExpBufferData buf;
/*
* Generate a "raw" nonce. This is converted to ASCII-printable form by
@ -328,26 +365,61 @@ build_client_first_message(fe_scram_state *state, PQExpBuffer errormessage)
* prepared with SASLprep, the message parsing would fail if it includes
* '=' or ',' characters.
*/
buflen = 8 + strlen(state->client_nonce) + 1;
buf = malloc(buflen);
if (buf == NULL)
{
printfPQExpBuffer(errormessage,
libpq_gettext("out of memory\n"));
return NULL;
}
snprintf(buf, buflen, "n,,n=,r=%s", state->client_nonce);
state->client_first_message_bare = strdup(buf + 3);
initPQExpBuffer(&buf);
/*
* First build the gs2-header with channel binding information.
*/
if (strcmp(state->sasl_mechanism, SCRAM_SHA256_PLUS_NAME) == 0)
{
Assert(state->ssl_in_use);
appendPQExpBuffer(&buf, "p=%s", state->channel_binding_type);
}
else if (state->ssl_in_use)
{
/*
* Client supports channel binding, but thinks the server does not.
*/
appendPQExpBuffer(&buf, "y");
}
else
{
/*
* Client does not support channel binding.
*/
appendPQExpBuffer(&buf, "n");
}
if (PQExpBufferDataBroken(buf))
goto oom_error;
channel_info_len = buf.len;
appendPQExpBuffer(&buf, ",,n=,r=%s", state->client_nonce);
if (PQExpBufferDataBroken(buf))
goto oom_error;
/*
* The first message content needs to be saved without channel binding
* information.
*/
state->client_first_message_bare = strdup(buf.data + channel_info_len + 2);
if (!state->client_first_message_bare)
{
free(buf);
goto oom_error;
result = strdup(buf.data);
if (result == NULL)
goto oom_error;
termPQExpBuffer(&buf);
return result;
oom_error:
termPQExpBuffer(&buf);
printfPQExpBuffer(errormessage,
libpq_gettext("out of memory\n"));
return NULL;
}
return buf;
}
/*
@ -366,7 +438,67 @@ build_client_final_message(fe_scram_state *state, PQExpBuffer errormessage)
* Construct client-final-message-without-proof. We need to remember it
* for verifying the server proof in the final step of authentication.
*/
appendPQExpBuffer(&buf, "c=biws,r=%s", state->nonce);
if (strcmp(state->sasl_mechanism, SCRAM_SHA256_PLUS_NAME) == 0)
{
char *cbind_data;
size_t cbind_data_len;
size_t cbind_header_len;
char *cbind_input;
size_t cbind_input_len;
if (strcmp(state->channel_binding_type, SCRAM_CHANNEL_BINDING_TLS_UNIQUE) == 0)
{
cbind_data = state->tls_finished_message;
cbind_data_len = state->tls_finished_len;
}
else
{
/* should not happen */
termPQExpBuffer(&buf);
printfPQExpBuffer(errormessage,
libpq_gettext("invalid channel binding type\n"));
return NULL;
}
/* should not happen */
if (cbind_data == NULL || cbind_data_len == 0)
{
termPQExpBuffer(&buf);
printfPQExpBuffer(errormessage,
libpq_gettext("empty channel binding data for channel binding type \"%s\"\n"),
state->channel_binding_type);
return NULL;
}
appendPQExpBuffer(&buf, "c=");
cbind_header_len = 4 + strlen(state->channel_binding_type); /* p=type,, */
cbind_input_len = cbind_header_len + cbind_data_len;
cbind_input = malloc(cbind_input_len);
if (!cbind_input)
goto oom_error;
snprintf(cbind_input, cbind_input_len, "p=%s,,", state->channel_binding_type);
memcpy(cbind_input + cbind_header_len, cbind_data, cbind_data_len);
if (!enlargePQExpBuffer(&buf, pg_b64_enc_len(cbind_input_len)))
{
free(cbind_input);
goto oom_error;
}
buf.len += pg_b64_encode(cbind_input, cbind_input_len, buf.data + buf.len);
buf.data[buf.len] = '\0';
free(cbind_input);
}
else if (state->ssl_in_use)
appendPQExpBuffer(&buf, "c=eSws"); /* base64 of "y,," */
else
appendPQExpBuffer(&buf, "c=biws"); /* base64 of "n,," */
if (PQExpBufferDataBroken(buf))
goto oom_error;
appendPQExpBuffer(&buf, ",r=%s", state->nonce);
if (PQExpBufferDataBroken(buf))
goto oom_error;

74
src/interfaces/libpq/fe-auth.c
View File

@ -491,6 +491,9 @@ pg_SASL_init(PGconn *conn, int payloadlen)
bool success;
const char *selected_mechanism;
PQExpBufferData mechanism_buf;
char *tls_finished = NULL;
size_t tls_finished_len = 0;
char *password;
initPQExpBuffer(&mechanism_buf);
@ -504,7 +507,8 @@ pg_SASL_init(PGconn *conn, int payloadlen)
/*
* Parse the list of SASL authentication mechanisms in the
* AuthenticationSASL message, and select the best mechanism that we
* support. (Only SCRAM-SHA-256 is supported at the moment.)
* support. SCRAM-SHA-256-PLUS and SCRAM-SHA-256 are the only ones
* supported at the moment, listed by order of decreasing importance.
*/
selected_mechanism = NULL;
for (;;)
@ -523,19 +527,36 @@ pg_SASL_init(PGconn *conn, int payloadlen)
break;
/*
* If we have already selected a mechanism, just skip through the rest
* of the list.
* Select the mechanism to use. Pick SCRAM-SHA-256-PLUS over anything
* else. Pick SCRAM-SHA-256 if nothing else has already been picked.
* If we add more mechanisms, a more refined priority mechanism might
* become necessary.
*/
if (selected_mechanism)
continue;
if (conn->ssl_in_use &&
strcmp(mechanism_buf.data, SCRAM_SHA256_PLUS_NAME) == 0)
selected_mechanism = SCRAM_SHA256_PLUS_NAME;
else if (strcmp(mechanism_buf.data, SCRAM_SHA256_NAME) == 0 &&
!selected_mechanism)
selected_mechanism = SCRAM_SHA256_NAME;
}
if (!selected_mechanism)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("none of the server's SASL authentication mechanisms are supported\n"));
goto error;
}
/*
* Do we support this mechanism?
* Now that the SASL mechanism has been chosen for the exchange,
* initialize its state information.
*/
if (strcmp(mechanism_buf.data, SCRAM_SHA256_NAME) == 0)
{
char *password;
/*
* First, select the password to use for the exchange, complaining if
* there isn't one. Currently, all supported SASL mechanisms require a
* password, so we can just go ahead here without further distinction.
*/
conn->password_needed = true;
password = conn->connhost[conn->whichhost].password;
if (password == NULL)
@ -547,19 +568,32 @@ pg_SASL_init(PGconn *conn, int payloadlen)
goto error;
}
conn->sasl_state = pg_fe_scram_init(conn->pguser, password);
#ifdef USE_SSL
/*
* Get data for channel binding.
*/
if (strcmp(selected_mechanism, SCRAM_SHA256_PLUS_NAME) == 0)
{
tls_finished = pgtls_get_finished(conn, &tls_finished_len);
if (tls_finished == NULL)
goto oom_error;
}
#endif
/*
* Initialize the SASL state information with all the information
* gathered during the initial exchange.
*
* Note: Only tls-unique is supported for the moment.
*/
conn->sasl_state = pg_fe_scram_init(conn->pguser,
password,
conn->ssl_in_use,
selected_mechanism,
tls_finished,
tls_finished_len);
if (!conn->sasl_state)
goto oom_error;
selected_mechanism = SCRAM_SHA256_NAME;
}
}
if (!selected_mechanism)
{
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("none of the server's SASL authentication mechanisms are supported\n"));
goto error;
}
/* Get the mechanism-specific Initial Client Response, if any */
pg_fe_scram_exchange(conn->sasl_state,

7
src/interfaces/libpq/fe-auth.h
View File

@ -23,7 +23,12 @@ extern int pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn);
extern char *pg_fe_getauthname(PQExpBuffer errorMessage);
/* Prototypes for functions in fe-auth-scram.c */
extern void *pg_fe_scram_init(const char *username, const char *password);
extern void *pg_fe_scram_init(const char *username,
const char *password,
bool ssl_in_use,
const char *sasl_mechanism,
char *tls_finished_message,
size_t tls_finished_len);
extern void pg_fe_scram_free(void *opaq);
extern void pg_fe_scram_exchange(void *opaq, char *input, int inputlen,
char **output, int *outputlen,

27
src/interfaces/libpq/fe-secure-openssl.c
View File

@ -393,6 +393,33 @@ pgtls_write(PGconn *conn, const void *ptr, size_t len)
return n;
}
/*
* Get the TLS finish message sent during last handshake
*
* This information is useful for callers doing channel binding during
* authentication.
*/
char *
pgtls_get_finished(PGconn *conn, size_t *len)
{
char dummy[1];
char *result;
/*
* OpenSSL does not offer an API to get directly the length of the TLS
* Finished message sent, so first do a dummy call to grab this
* information and then do an allocation with the correct size.
*/
*len = SSL_get_finished(conn->ssl, dummy, sizeof(dummy));
result = malloc(*len);
if (result == NULL)
return NULL;
(void) SSL_get_finished(conn->ssl, result, *len);
return result;
}
/* ------------------------------------------------------------ */
/* OpenSSL specific code */
/* ------------------------------------------------------------ */

5
src/interfaces/libpq/libpq-int.h
View File

@ -453,11 +453,13 @@ struct pg_conn
/* Assorted state for SASL, SSL, GSS, etc */
void *sasl_state;
/* SSL structures */
bool ssl_in_use;
#ifdef USE_SSL
bool allow_ssl_try; /* Allowed to try SSL negotiation */
bool wait_ssl_try; /* Delay SSL negotiation until after
* attempting normal connection */
bool ssl_in_use;
#ifdef USE_OPENSSL
SSL *ssl; /* SSL status, if have SSL connection */
X509 *peer; /* X509 cert of server */
@ -668,6 +670,7 @@ extern void pgtls_close(PGconn *conn);
extern ssize_t pgtls_read(PGconn *conn, void *ptr, size_t len);
extern bool pgtls_read_pending(PGconn *conn);
extern ssize_t pgtls_write(PGconn *conn, const void *ptr, size_t len);
extern char *pgtls_get_finished(PGconn *conn, size_t *len);
/*
* this is so that we can check if a connection is non-blocking internally

27
src/test/ssl/ServerSetup.pm
View File

@ -57,19 +57,21 @@ sub test_connect_ok
{
my $common_connstr = $_[0];
my $connstr = $_[1];
my $test_name = $_[2];
my $result =
run_test_psql("$common_connstr $connstr", "(should succeed)");
ok($result, $connstr);
ok($result, $test_name || $connstr);
}
sub test_connect_fails
{
my $common_connstr = $_[0];
my $connstr = $_[1];
my $test_name = $_[2];
my $result = run_test_psql("$common_connstr $connstr", "(should fail)");
ok(!$result, "$connstr (should fail)");
ok(!$result, $test_name || "$connstr (should fail)");
}
# Copy a set of files, taking into account wildcards
@ -89,8 +91,7 @@ sub copy_files
sub configure_test_server_for_ssl
{
my $node = $_[0];
my $serverhost = $_[1];
my ($node, $serverhost, $authmethod, $password, $password_enc) = @_;
my $pgdata = $node->data_dir;
@ -100,6 +101,15 @@ sub configure_test_server_for_ssl
$node->psql('postgres', "CREATE DATABASE trustdb");
$node->psql('postgres', "CREATE DATABASE certdb");
# Update password of each user as needed.
if (defined($password))
{
$node->psql('postgres',
"SET password_encryption='$password_enc'; ALTER USER ssltestuser PASSWORD '$password';");
$node->psql('postgres',
"SET password_encryption='$password_enc'; ALTER USER anotheruser PASSWORD '$password';");
}
# enable logging etc.
open my $conf, '>>', "$pgdata/postgresql.conf";
print $conf "fsync=off\n";
@ -129,7 +139,7 @@ sub configure_test_server_for_ssl
$node->restart;
# Change pg_hba after restart because hostssl requires ssl=on
configure_hba_for_ssl($node, $serverhost);
configure_hba_for_ssl($node, $serverhost, $authmethod);
}
# Change the configuration to use given server cert file, and reload
@ -157,8 +167,7 @@ sub switch_server_cert
sub configure_hba_for_ssl
{
my $node = $_[0];
my $serverhost = $_[1];
my ($node, $serverhost, $authmethod) = @_;
my $pgdata = $node->data_dir;
# Only accept SSL connections from localhost. Our tests don't depend on this
@ -169,9 +178,9 @@ sub configure_hba_for_ssl
print $hba
"# TYPE DATABASE USER ADDRESS METHOD\n";
print $hba
"hostssl trustdb ssltestuser $serverhost/32 trust\n";
"hostssl trustdb ssltestuser $serverhost/32 $authmethod\n";
print $hba
"hostssl trustdb ssltestuser ::1/128 trust\n";
"hostssl trustdb ssltestuser ::1/128 $authmethod\n";
print $hba
"hostssl certdb ssltestuser $serverhost/32 cert\n";
print $hba

2
src/test/ssl/t/001_ssltests.pl
View File

@ -32,7 +32,7 @@ $node->init;
$ENV{PGHOST} = $node->host;
$ENV{PGPORT} = $node->port;
$node->start;
configure_test_server_for_ssl($node, $SERVERHOSTADDR);
configure_test_server_for_ssl($node, $SERVERHOSTADDR, 'trust');
switch_server_cert($node, 'server-cn-only');
### Part 1. Run client-side tests.

38
src/test/ssl/t/002_scram.pl Normal file
View File

@ -0,0 +1,38 @@
# Test SCRAM authentication and TLS channel binding types
use strict;
use warnings;
use PostgresNode;
use TestLib;
use Test::More tests => 1;
use ServerSetup;
use File::Copy;
# This is the hostname used to connect to the server.
my $SERVERHOSTADDR = '127.0.0.1';
# Allocation of base connection string shared among multiple tests.
my $common_connstr;
# Set up the server.
note "setting up data directory";
my $node = get_new_node('master');
$node->init;
# PGHOST is enforced here to set up the node, subsequent connections
# will use a dedicated connection string.
$ENV{PGHOST} = $node->host;
$ENV{PGPORT} = $node->port;
$node->start;
# Configure server for SSL connections, with password handling.
configure_test_server_for_ssl($node, $SERVERHOSTADDR, "scram-sha-256",
"pass", "scram-sha-256");
switch_server_cert($node, 'server-cn-only');
$ENV{PGPASSWORD} = "pass";
$common_connstr =
"user=ssltestuser dbname=trustdb sslmode=require hostaddr=$SERVERHOSTADDR";
test_connect_ok($common_connstr, '',
"SCRAM authentication with default channel binding");