fe-auth.c File Reference

#include "postgres_fe.h"
#include <unistd.h>
#include <fcntl.h>
#include <limits.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <netdb.h>
#include "common/md5.h"
#include "common/scram-common.h"
#include "fe-auth.h"
#include "fe-auth-sasl.h"
#include "libpq-fe.h"

Include dependency graph for fe-auth.c:

Go to the source code of this file.

Macros
#define	auth_method_allowed(conn, type)    (((conn)->allowed_auth_methods & (1 << (type))) != 0)
#define	MAX_ALGORITHM_NAME_LEN   50

Functions
static int	pg_SASL_init (PGconn *conn, int payloadlen)
static int	pg_SASL_continue (PGconn *conn, int payloadlen, bool final)
static int	pg_password_sendauth (PGconn *conn, const char *password, AuthRequest areq)
static const char *	auth_method_description (AuthRequest areq)
static bool	check_expected_areq (AuthRequest areq, PGconn *conn)
int	pg_fe_sendauth (AuthRequest areq, int payloadlen, PGconn *conn)
char *	pg_fe_getusername (uid_t user_id, PQExpBuffer errorMessage)
char *	pg_fe_getauthname (PQExpBuffer errorMessage)
char *	PQencryptPassword (const char *passwd, const char *user)
char *	PQencryptPasswordConn (PGconn *conn, const char *passwd, const char *user, const char *algorithm)

Macro Definition Documentation

auth_method_allowed

#define auth_method_allowed	(		conn,
			type
	)		(((conn)->allowed_auth_methods & (1 << (type))) != 0)

Definition at line 794 of file fe-auth.c.

MAX_ALGORITHM_NAME_LEN

#define MAX_ALGORITHM_NAME_LEN   50

Function Documentation

auth_method_description()

static const char* auth_method_description ( AuthRequest  areq )

static

Definition at line 768 of file fe-auth.c.

{
    switch (areq)
    {
        case AUTH_REQ_PASSWORD:
            return libpq_gettext("server requested a cleartext password");
        case AUTH_REQ_MD5:
            return libpq_gettext("server requested a hashed password");
        case AUTH_REQ_GSS:
        case AUTH_REQ_GSS_CONT:
            return libpq_gettext("server requested GSSAPI authentication");
        case AUTH_REQ_SSPI:
            return libpq_gettext("server requested SSPI authentication");
        case AUTH_REQ_SASL:
        case AUTH_REQ_SASL_CONT:
        case AUTH_REQ_SASL_FIN:
            return libpq_gettext("server requested SASL authentication");
    }
 
    return libpq_gettext("server requested an unknown authentication type");
}

References AUTH_REQ_GSS, AUTH_REQ_GSS_CONT, AUTH_REQ_MD5, AUTH_REQ_PASSWORD, AUTH_REQ_SASL, AUTH_REQ_SASL_CONT, AUTH_REQ_SASL_FIN, AUTH_REQ_SSPI, and libpq_gettext.

Referenced by check_expected_areq().

check_expected_areq()

static bool check_expected_areq ( AuthRequest  areq, PGconn *  conn  )

static

Definition at line 803 of file fe-auth.c.

{
    bool        result = true;
    const char *reason = NULL;
 
    StaticAssertDecl((sizeof(conn->allowed_auth_methods) * CHAR_BIT) > AUTH_REQ_MAX,
                     "AUTH_REQ_MAX overflows the allowed_auth_methods bitmask");
 
    if (conn->sslcertmode[0] == 'r' /* require */
        && areq == AUTH_REQ_OK)
    {
        /*
         * Trade off a little bit of complexity to try to get these error
         * messages as precise as possible.
         */
        if (!conn->ssl_cert_requested)
        {
            libpq_append_conn_error(conn, "server did not request an SSL certificate");
            return false;
        }
        else if (!conn->ssl_cert_sent)
        {
            libpq_append_conn_error(conn, "server accepted connection without a valid SSL certificate");
            return false;
        }
    }
 
    /*
     * If the user required a specific auth method, or specified an allowed
     * set, then reject all others here, and make sure the server actually
     * completes an authentication exchange.
     */
    if (conn->require_auth)
    {
        switch (areq)
        {
            case AUTH_REQ_OK:
 
                /*
                 * Check to make sure we've actually finished our exchange (or
                 * else that the user has allowed an authentication-less
                 * connection).
                 *
                 * If the user has allowed both SCRAM and unauthenticated
                 * (trust) connections, then this check will silently accept
                 * partial SCRAM exchanges, where a misbehaving server does
                 * not provide its verifier before sending an OK.  This is
                 * consistent with historical behavior, but it may be a point
                 * to revisit in the future, since it could allow a server
                 * that doesn't know the user's password to silently harvest
                 * material for a brute force attack.
                 */
                if (!conn->auth_required || conn->client_finished_auth)
                    break;
 
                /*
                 * No explicit authentication request was made by the server
                 * -- or perhaps it was made and not completed, in the case of
                 * SCRAM -- but there is one special case to check.  If the
                 * user allowed "gss", then a GSS-encrypted channel also
                 * satisfies the check.
                 */
#ifdef ENABLE_GSS
                if (auth_method_allowed(conn, AUTH_REQ_GSS) && conn->gssenc)
                {
                    /*
                     * If implicit GSS auth has already been performed via GSS
                     * encryption, we don't need to have performed an
                     * AUTH_REQ_GSS exchange.  This allows require_auth=gss to
                     * be combined with gssencmode, since there won't be an
                     * explicit authentication request in that case.
                     */
                }
                else
#endif
                {
                    reason = libpq_gettext("server did not complete authentication");
                    result = false;
                }
 
                break;
 
            case AUTH_REQ_PASSWORD:
            case AUTH_REQ_MD5:
            case AUTH_REQ_GSS:
            case AUTH_REQ_GSS_CONT:
            case AUTH_REQ_SSPI:
            case AUTH_REQ_SASL:
            case AUTH_REQ_SASL_CONT:
            case AUTH_REQ_SASL_FIN:
 
                /*
                 * We don't handle these with the default case, to avoid
                 * bit-shifting past the end of the allowed_auth_methods mask
                 * if the server sends an unexpected AuthRequest.
                 */
                result = auth_method_allowed(conn, areq);
                break;
 
            default:
                result = false;
                break;
        }
    }
 
    if (!result)
    {
        if (!reason)
            reason = auth_method_description(areq);
 
        libpq_append_conn_error(conn, "authentication method requirement \"%s\" failed: %s",
                                conn->require_auth, reason);
        return result;
    }
 
    /*
     * When channel_binding=require, we must protect against two cases: (1) we
     * must not respond to non-SASL authentication requests, which might leak
     * information such as the client's password; and (2) even if we receive
     * AUTH_REQ_OK, we still must ensure that channel binding has happened in
     * order to authenticate the server.
     */
    if (conn->channel_binding[0] == 'r' /* require */ )
    {
        switch (areq)
        {
            case AUTH_REQ_SASL:
            case AUTH_REQ_SASL_CONT:
            case AUTH_REQ_SASL_FIN:
                break;
            case AUTH_REQ_OK:
                if (!conn->sasl || !conn->sasl->channel_bound(conn->sasl_state))
                {
                    libpq_append_conn_error(conn, "channel binding required, but server authenticated client without channel binding");
                    result = false;
                }
                break;
            default:
                libpq_append_conn_error(conn, "channel binding required but not supported by server's authentication request");
                result = false;
                break;
        }
    }
 
    return result;
}

References pg_conn::allowed_auth_methods, auth_method_allowed, auth_method_description(), AUTH_REQ_GSS, AUTH_REQ_GSS_CONT, AUTH_REQ_MAX, AUTH_REQ_MD5, AUTH_REQ_OK, AUTH_REQ_PASSWORD, AUTH_REQ_SASL, AUTH_REQ_SASL_CONT, AUTH_REQ_SASL_FIN, AUTH_REQ_SSPI, pg_conn::auth_required, pg_conn::channel_binding, pg_fe_sasl_mech::channel_bound, pg_conn::client_finished_auth, conn, libpq_append_conn_error(), libpq_gettext, pg_conn::require_auth, pg_conn::sasl, pg_conn::sasl_state, pg_conn::ssl_cert_requested, pg_conn::ssl_cert_sent, pg_conn::sslcertmode, and StaticAssertDecl.

Referenced by pg_fe_sendauth().

pg_fe_getauthname()

char* pg_fe_getauthname

(

PQExpBuffer

errorMessage

)

Definition at line 1215 of file fe-auth.c.

{
#ifdef WIN32
    return pg_fe_getusername(0, errorMessage);
#else
    return pg_fe_getusername(geteuid(), errorMessage);
#endif
}

References pg_fe_getusername().

Referenced by connectOptions2(), and conninfo_add_defaults().

pg_fe_getusername()

char* pg_fe_getusername	(	uid_t	user_id,
		PQExpBuffer	errorMessage
	)

Definition at line 1170 of file fe-auth.c.

{
    char       *result = NULL;
    const char *name = NULL;
 
#ifdef WIN32
    /* Microsoft recommends buffer size of UNLEN+1, where UNLEN = 256 */
    char        username[256 + 1];
    DWORD       namesize = sizeof(username);
#else
    char        pwdbuf[BUFSIZ];
#endif
 
#ifdef WIN32
    if (GetUserName(username, &namesize))
        name = username;
    else if (errorMessage)
        libpq_append_error(errorMessage,
                           "user name lookup failure: error code %lu",
                           GetLastError());
#else
    if (pg_get_user_name(user_id, pwdbuf, sizeof(pwdbuf)))
        name = pwdbuf;
    else if (errorMessage)
        appendPQExpBuffer(errorMessage, "%s\n", pwdbuf);
#endif
 
    if (name)
    {
        result = strdup(name);
        if (result == NULL && errorMessage)
            libpq_append_error(errorMessage, "out of memory");
    }
 
    return result;
}

References appendPQExpBuffer(), libpq_append_error(), name, pg_get_user_name(), and username.

Referenced by pg_fe_getauthname(), and PQconnectPoll().

pg_fe_sendauth()

int pg_fe_sendauth	(	AuthRequest	areq,
		int	payloadlen,
		PGconn *	conn
	)

Definition at line 962 of file fe-auth.c.

{
    int         oldmsglen;
 
    if (!check_expected_areq(areq, conn))
        return STATUS_ERROR;
 
    switch (areq)
    {
        case AUTH_REQ_OK:
            break;
 
        case AUTH_REQ_KRB4:
            libpq_append_conn_error(conn, "Kerberos 4 authentication not supported");
            return STATUS_ERROR;
 
        case AUTH_REQ_KRB5:
            libpq_append_conn_error(conn, "Kerberos 5 authentication not supported");
            return STATUS_ERROR;
 
#if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
        case AUTH_REQ_GSS:
#if !defined(ENABLE_SSPI)
            /* no native SSPI, so use GSSAPI library for it */
        case AUTH_REQ_SSPI:
#endif
            {
                int         r;
 
                pglock_thread();
 
                /*
                 * If we have both GSS and SSPI support compiled in, use SSPI
                 * support by default. This is overridable by a connection
                 * string parameter. Note that when using SSPI we still leave
                 * the negotiate parameter off, since we want SSPI to use the
                 * GSSAPI kerberos protocol. For actual SSPI negotiate
                 * protocol, we use AUTH_REQ_SSPI.
                 */
#if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
                if (conn->gsslib && (pg_strcasecmp(conn->gsslib, "gssapi") == 0))
                    r = pg_GSS_startup(conn, payloadlen);
                else
                    r = pg_SSPI_startup(conn, 0, payloadlen);
#elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
                r = pg_GSS_startup(conn, payloadlen);
#elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
                r = pg_SSPI_startup(conn, 0, payloadlen);
#endif
                if (r != STATUS_OK)
                {
                    /* Error message already filled in. */
                    pgunlock_thread();
                    return STATUS_ERROR;
                }
                pgunlock_thread();
            }
            break;
 
        case AUTH_REQ_GSS_CONT:
            {
                int         r;
 
                pglock_thread();
#if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
                if (conn->usesspi)
                    r = pg_SSPI_continue(conn, payloadlen);
                else
                    r = pg_GSS_continue(conn, payloadlen);
#elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
                r = pg_GSS_continue(conn, payloadlen);
#elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
                r = pg_SSPI_continue(conn, payloadlen);
#endif
                if (r != STATUS_OK)
                {
                    /* Error message already filled in. */
                    pgunlock_thread();
                    return STATUS_ERROR;
                }
                pgunlock_thread();
            }
            break;
#else                           /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
            /* No GSSAPI *or* SSPI support */
        case AUTH_REQ_GSS:
        case AUTH_REQ_GSS_CONT:
            libpq_append_conn_error(conn, "GSSAPI authentication not supported");
            return STATUS_ERROR;
#endif                          /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
 
#ifdef ENABLE_SSPI
        case AUTH_REQ_SSPI:
 
            /*
             * SSPI has its own startup message so libpq can decide which
             * method to use. Indicate to pg_SSPI_startup that we want SSPI
             * negotiation instead of Kerberos.
             */
            pglock_thread();
            if (pg_SSPI_startup(conn, 1, payloadlen) != STATUS_OK)
            {
                /* Error message already filled in. */
                pgunlock_thread();
                return STATUS_ERROR;
            }
            pgunlock_thread();
            break;
#else
 
            /*
             * No SSPI support. However, if we have GSSAPI but not SSPI
             * support, AUTH_REQ_SSPI will have been handled in the codepath
             * for AUTH_REQ_GSS above, so don't duplicate the case label in
             * that case.
             */
#if !defined(ENABLE_GSS)
        case AUTH_REQ_SSPI:
            libpq_append_conn_error(conn, "SSPI authentication not supported");
            return STATUS_ERROR;
#endif                          /* !define(ENABLE_GSS) */
#endif                          /* ENABLE_SSPI */
 
 
        case AUTH_REQ_CRYPT:
            libpq_append_conn_error(conn, "Crypt authentication not supported");
            return STATUS_ERROR;
 
        case AUTH_REQ_MD5:
        case AUTH_REQ_PASSWORD:
            {
                char       *password;
 
                conn->password_needed = true;
                password = conn->connhost[conn->whichhost].password;
                if (password == NULL)
                    password = conn->pgpass;
                if (password == NULL || password[0] == '\0')
                {
                    appendPQExpBufferStr(&conn->errorMessage,
                                         PQnoPasswordSupplied);
                    return STATUS_ERROR;
                }
                if (pg_password_sendauth(conn, password, areq) != STATUS_OK)
                {
                    appendPQExpBufferStr(&conn->errorMessage,
                                         "fe_sendauth: error sending password authentication\n");
                    return STATUS_ERROR;
                }
 
                /* We expect no further authentication requests. */
                conn->client_finished_auth = true;
                break;
            }
 
        case AUTH_REQ_SASL:
 
            /*
             * The request contains the name (as assigned by IANA) of the
             * authentication mechanism.
             */
            if (pg_SASL_init(conn, payloadlen) != STATUS_OK)
            {
                /* pg_SASL_init already set the error message */
                return STATUS_ERROR;
            }
            break;
 
        case AUTH_REQ_SASL_CONT:
        case AUTH_REQ_SASL_FIN:
            if (conn->sasl_state == NULL)
            {
                appendPQExpBufferStr(&conn->errorMessage,
                                     "fe_sendauth: invalid authentication request from server: AUTH_REQ_SASL_CONT without AUTH_REQ_SASL\n");
                return STATUS_ERROR;
            }
            oldmsglen = conn->errorMessage.len;
            if (pg_SASL_continue(conn, payloadlen,
                                 (areq == AUTH_REQ_SASL_FIN)) != STATUS_OK)
            {
                /* Use this message if pg_SASL_continue didn't supply one */
                if (conn->errorMessage.len == oldmsglen)
                    appendPQExpBufferStr(&conn->errorMessage,
                                         "fe_sendauth: error in SASL authentication\n");
                return STATUS_ERROR;
            }
            break;
 
        default:
            libpq_append_conn_error(conn, "authentication method %u not supported", areq);
            return STATUS_ERROR;
    }
 
    return STATUS_OK;
}

References appendPQExpBufferStr(), AUTH_REQ_CRYPT, AUTH_REQ_GSS, AUTH_REQ_GSS_CONT, AUTH_REQ_KRB4, AUTH_REQ_KRB5, AUTH_REQ_MD5, AUTH_REQ_OK, AUTH_REQ_PASSWORD, AUTH_REQ_SASL, AUTH_REQ_SASL_CONT, AUTH_REQ_SASL_FIN, AUTH_REQ_SSPI, check_expected_areq(), pg_conn::client_finished_auth, conn, pg_conn::connhost, pg_conn::errorMessage, pg_conn::gsslib, PQExpBufferData::len, libpq_append_conn_error(), password, pg_conn_host::password, pg_conn::password_needed, pg_password_sendauth(), pg_SASL_continue(), pg_SASL_init(), pg_strcasecmp(), pglock_thread, pg_conn::pgpass, pgunlock_thread, PQnoPasswordSupplied, pg_conn::sasl_state, STATUS_ERROR, STATUS_OK, and pg_conn::whichhost.

Referenced by PQconnectPoll().

pg_password_sendauth()

static int pg_password_sendauth ( PGconn *  conn, const char *  password, AuthRequest  areq  )

static

Definition at line 702 of file fe-auth.c.

{
    int         ret;
    char       *crypt_pwd = NULL;
    const char *pwd_to_send;
    char        md5Salt[4];
 
    /* Read the salt from the AuthenticationMD5Password message. */
    if (areq == AUTH_REQ_MD5)
    {
        if (pqGetnchar(md5Salt, 4, conn))
            return STATUS_ERROR;    /* shouldn't happen */
    }
 
    /* Encrypt the password if needed. */
 
    switch (areq)
    {
        case AUTH_REQ_MD5:
            {
                char       *crypt_pwd2;
                const char *errstr = NULL;
 
                /* Allocate enough space for two MD5 hashes */
                crypt_pwd = malloc(2 * (MD5_PASSWD_LEN + 1));
                if (!crypt_pwd)
                {
                    libpq_append_conn_error(conn, "out of memory");
                    return STATUS_ERROR;
                }
 
                crypt_pwd2 = crypt_pwd + MD5_PASSWD_LEN + 1;
                if (!pg_md5_encrypt(password, conn->pguser,
                                    strlen(conn->pguser), crypt_pwd2,
                                    &errstr))
                {
                    libpq_append_conn_error(conn, "could not encrypt password: %s", errstr);
                    free(crypt_pwd);
                    return STATUS_ERROR;
                }
                if (!pg_md5_encrypt(crypt_pwd2 + strlen("md5"), md5Salt,
                                    4, crypt_pwd, &errstr))
                {
                    libpq_append_conn_error(conn, "could not encrypt password: %s", errstr);
                    free(crypt_pwd);
                    return STATUS_ERROR;
                }
 
                pwd_to_send = crypt_pwd;
                break;
            }
        case AUTH_REQ_PASSWORD:
            pwd_to_send = password;
            break;
        default:
            return STATUS_ERROR;
    }
    ret = pqPacketSend(conn, 'p', pwd_to_send, strlen(pwd_to_send) + 1);
    free(crypt_pwd);
    return ret;
}

References AUTH_REQ_MD5, AUTH_REQ_PASSWORD, conn, free, libpq_append_conn_error(), malloc, MD5_PASSWD_LEN, password, pg_md5_encrypt(), pg_conn::pguser, pqGetnchar(), pqPacketSend(), and STATUS_ERROR.

Referenced by pg_fe_sendauth().

pg_SASL_continue()

static int pg_SASL_continue ( PGconn *  conn, int  payloadlen, bool  final  )

static

Definition at line 628 of file fe-auth.c.

{
    char       *output;
    int         outputlen;
    bool        done;
    bool        success;
    int         res;
    char       *challenge;
 
    /* Read the SASL challenge from the AuthenticationSASLContinue message. */
    challenge = malloc(payloadlen + 1);
    if (!challenge)
    {
        libpq_append_conn_error(conn, "out of memory allocating SASL buffer (%d)",
                                payloadlen);
        return STATUS_ERROR;
    }
 
    if (pqGetnchar(challenge, payloadlen, conn))
    {
        free(challenge);
        return STATUS_ERROR;
    }
    /* For safety and convenience, ensure the buffer is NULL-terminated. */
    challenge[payloadlen] = '\0';
 
    conn->sasl->exchange(conn->sasl_state,
                         challenge, payloadlen,
                         &output, &outputlen,
                         &done, &success);
    free(challenge);            /* don't need the input anymore */
 
    if (final && !done)
    {
        if (outputlen != 0)
            free(output);
 
        libpq_append_conn_error(conn, "AuthenticationSASLFinal received from server, but SASL authentication was not completed");
        return STATUS_ERROR;
    }
 
    /*
     * If the exchange is not completed yet, we need to make sure that the
     * SASL mechanism has generated a message to send back.
     */
    if (output == NULL && !done)
    {
        libpq_append_conn_error(conn, "no client response found after SASL exchange success");
        return STATUS_ERROR;
    }
 
    /*
     * SASL allows zero-length responses, so this check uses "output" and not
     * "outputlen" to allow the case of an empty message.
     */
    if (output)
    {
        /*
         * Send the SASL response to the server.
         */
        res = pqPacketSend(conn, 'p', output, outputlen);
        free(output);
 
        if (res != STATUS_OK)
            return STATUS_ERROR;
    }
 
    if (done && !success)
        return STATUS_ERROR;
 
    return STATUS_OK;
}

References conn, pg_fe_sasl_mech::exchange, free, libpq_append_conn_error(), malloc, output, pqGetnchar(), pqPacketSend(), res, pg_conn::sasl, pg_conn::sasl_state, STATUS_ERROR, STATUS_OK, and success.

Referenced by pg_fe_sendauth().

pg_SASL_init()

static int pg_SASL_init ( PGconn *  conn, int  payloadlen  )

static

Definition at line 422 of file fe-auth.c.

{
    char       *initialresponse = NULL;
    int         initialresponselen;
    bool        done;
    bool        success;
    const char *selected_mechanism;
    PQExpBufferData mechanism_buf;
    char       *password;
 
    initPQExpBuffer(&mechanism_buf);
 
    if (conn->channel_binding[0] == 'r' &&  /* require */
        !conn->ssl_in_use)
    {
        libpq_append_conn_error(conn, "channel binding required, but SSL not in use");
        goto error;
    }
 
    if (conn->sasl_state)
    {
        libpq_append_conn_error(conn, "duplicate SASL authentication request");
        goto error;
    }
 
    /*
     * Parse the list of SASL authentication mechanisms in the
     * AuthenticationSASL message, and select the best mechanism that we
     * 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 (;;)
    {
        if (pqGets(&mechanism_buf, conn))
        {
            appendPQExpBufferStr(&conn->errorMessage,
                                 "fe_sendauth: invalid authentication request from server: invalid list of authentication mechanisms\n");
            goto error;
        }
        if (PQExpBufferDataBroken(mechanism_buf))
            goto oom_error;
 
        /* An empty string indicates end of list */
        if (mechanism_buf.data[0] == '\0')
            break;
 
        /*
         * Select the mechanism to use.  Pick SCRAM-SHA-256-PLUS over anything
         * else if a channel binding type is set and if the client supports it
         * (and did not set channel_binding=disable). 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 (strcmp(mechanism_buf.data, SCRAM_SHA_256_PLUS_NAME) == 0)
        {
            if (conn->ssl_in_use)
            {
                /* The server has offered SCRAM-SHA-256-PLUS. */
 
#ifdef USE_SSL
                /*
                 * The client supports channel binding, which is chosen if
                 * channel_binding is not disabled.
                 */
                if (conn->channel_binding[0] != 'd')    /* disable */
                {
                    selected_mechanism = SCRAM_SHA_256_PLUS_NAME;
                    conn->sasl = &pg_scram_mech;
                }
#else
                /*
                 * The client does not support channel binding.  If it is
                 * required, complain immediately instead of the error below
                 * which would be confusing as the server is publishing
                 * SCRAM-SHA-256-PLUS.
                 */
                if (conn->channel_binding[0] == 'r')    /* require */
                {
                    libpq_append_conn_error(conn, "channel binding is required, but client does not support it");
                    goto error;
                }
#endif
            }
            else
            {
                /*
                 * The server offered SCRAM-SHA-256-PLUS, but the connection
                 * is not SSL-encrypted. That's not sane. Perhaps SSL was
                 * stripped by a proxy? There's no point in continuing,
                 * because the server will reject the connection anyway if we
                 * try authenticate without channel binding even though both
                 * the client and server supported it. The SCRAM exchange
                 * checks for that, to prevent downgrade attacks.
                 */
                libpq_append_conn_error(conn, "server offered SCRAM-SHA-256-PLUS authentication over a non-SSL connection");
                goto error;
            }
        }
        else if (strcmp(mechanism_buf.data, SCRAM_SHA_256_NAME) == 0 &&
                 !selected_mechanism)
        {
            selected_mechanism = SCRAM_SHA_256_NAME;
            conn->sasl = &pg_scram_mech;
        }
    }
 
    if (!selected_mechanism)
    {
        libpq_append_conn_error(conn, "none of the server's SASL authentication mechanisms are supported");
        goto error;
    }
 
    if (conn->channel_binding[0] == 'r' &&  /* require */
        strcmp(selected_mechanism, SCRAM_SHA_256_PLUS_NAME) != 0)
    {
        libpq_append_conn_error(conn, "channel binding is required, but server did not offer an authentication method that supports channel binding");
        goto error;
    }
 
    /*
     * Now that the SASL mechanism has been chosen for the exchange,
     * initialize its state information.
     */
 
    /*
     * 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)
        password = conn->pgpass;
    if (password == NULL || password[0] == '\0')
    {
        appendPQExpBufferStr(&conn->errorMessage,
                             PQnoPasswordSupplied);
        goto error;
    }
 
    Assert(conn->sasl);
 
    /*
     * 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 = conn->sasl->init(conn,
                                        password,
                                        selected_mechanism);
    if (!conn->sasl_state)
        goto oom_error;
 
    /* Get the mechanism-specific Initial Client Response, if any */
    conn->sasl->exchange(conn->sasl_state,
                         NULL, -1,
                         &initialresponse, &initialresponselen,
                         &done, &success);
 
    if (done && !success)
        goto error;
 
    /*
     * Build a SASLInitialResponse message, and send it.
     */
    if (pqPutMsgStart(PqMsg_SASLInitialResponse, conn))
        goto error;
    if (pqPuts(selected_mechanism, conn))
        goto error;
    if (initialresponse)
    {
        if (pqPutInt(initialresponselen, 4, conn))
            goto error;
        if (pqPutnchar(initialresponse, initialresponselen, conn))
            goto error;
    }
    if (pqPutMsgEnd(conn))
        goto error;
    if (pqFlush(conn))
        goto error;
 
    termPQExpBuffer(&mechanism_buf);
    free(initialresponse);
 
    return STATUS_OK;
 
error:
    termPQExpBuffer(&mechanism_buf);
    free(initialresponse);
    return STATUS_ERROR;
 
oom_error:
    termPQExpBuffer(&mechanism_buf);
    free(initialresponse);
    libpq_append_conn_error(conn, "out of memory");
    return STATUS_ERROR;
}

References appendPQExpBufferStr(), Assert(), pg_conn::channel_binding, conn, pg_conn::connhost, PQExpBufferData::data, error(), pg_conn::errorMessage, pg_fe_sasl_mech::exchange, free, pg_fe_sasl_mech::init, initPQExpBuffer(), libpq_append_conn_error(), password, pg_conn_host::password, pg_conn::password_needed, pg_scram_mech, pg_conn::pgpass, PQExpBufferDataBroken, pqFlush(), pqGets(), PqMsg_SASLInitialResponse, PQnoPasswordSupplied, pqPutInt(), pqPutMsgEnd(), pqPutMsgStart(), pqPutnchar(), pqPuts(), pg_conn::sasl, pg_conn::sasl_state, SCRAM_SHA_256_NAME, SCRAM_SHA_256_PLUS_NAME, pg_conn::ssl_in_use, STATUS_ERROR, STATUS_OK, success, termPQExpBuffer(), and pg_conn::whichhost.

Referenced by pg_fe_sendauth().

PQencryptPassword()

char* PQencryptPassword	(	const char *	passwd,
		const char *	user
	)

Definition at line 1234 of file fe-auth.c.

{
    char       *crypt_pwd;
    const char *errstr = NULL;
 
    crypt_pwd = malloc(MD5_PASSWD_LEN + 1);
    if (!crypt_pwd)
        return NULL;
 
    if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd, &errstr))
    {
        free(crypt_pwd);
        return NULL;
    }
 
    return crypt_pwd;
}

References free, malloc, MD5_PASSWD_LEN, pg_md5_encrypt(), and user.

PQencryptPasswordConn()

char* PQencryptPasswordConn	(	PGconn *	conn,
		const char *	passwd,
		const char *	user,
		const char *	algorithm
	)

Definition at line 1277 of file fe-auth.c.

{
#define MAX_ALGORITHM_NAME_LEN 50
    char        algobuf[MAX_ALGORITHM_NAME_LEN + 1];
    char       *crypt_pwd = NULL;
 
    if (!conn)
        return NULL;
 
    pqClearConnErrorState(conn);
 
    /* If no algorithm was given, ask the server. */
    if (algorithm == NULL)
    {
        PGresult   *res;
        char       *val;
 
        res = PQexec(conn, "show password_encryption");
        if (res == NULL)
        {
            /* PQexec() should've set conn->errorMessage already */
            return NULL;
        }
        if (PQresultStatus(res) != PGRES_TUPLES_OK)
        {
            /* PQexec() should've set conn->errorMessage already */
            PQclear(res);
            return NULL;
        }
        if (PQntuples(res) != 1 || PQnfields(res) != 1)
        {
            PQclear(res);
            libpq_append_conn_error(conn, "unexpected shape of result set returned for SHOW");
            return NULL;
        }
        val = PQgetvalue(res, 0, 0);
 
        if (strlen(val) > MAX_ALGORITHM_NAME_LEN)
        {
            PQclear(res);
            libpq_append_conn_error(conn, "password_encryption value too long");
            return NULL;
        }
        strcpy(algobuf, val);
        PQclear(res);
 
        algorithm = algobuf;
    }
 
    /*
     * Also accept "on" and "off" as aliases for "md5", because
     * password_encryption was a boolean before PostgreSQL 10.  We refuse to
     * send the password in plaintext even if it was "off".
     */
    if (strcmp(algorithm, "on") == 0 ||
        strcmp(algorithm, "off") == 0)
        algorithm = "md5";
 
    /*
     * Ok, now we know what algorithm to use
     */
    if (strcmp(algorithm, "scram-sha-256") == 0)
    {
        const char *errstr = NULL;
 
        crypt_pwd = pg_fe_scram_build_secret(passwd,
                                             conn->scram_sha_256_iterations,
                                             &errstr);
        if (!crypt_pwd)
            libpq_append_conn_error(conn, "could not encrypt password: %s", errstr);
    }
    else if (strcmp(algorithm, "md5") == 0)
    {
        crypt_pwd = malloc(MD5_PASSWD_LEN + 1);
        if (crypt_pwd)
        {
            const char *errstr = NULL;
 
            if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd, &errstr))
            {
                libpq_append_conn_error(conn, "could not encrypt password: %s", errstr);
                free(crypt_pwd);
                crypt_pwd = NULL;
            }
        }
        else
            libpq_append_conn_error(conn, "out of memory");
    }
    else
    {
        libpq_append_conn_error(conn, "unrecognized password encryption algorithm \"%s\"",
                                algorithm);
        return NULL;
    }
 
    return crypt_pwd;
}

References conn, free, libpq_append_conn_error(), malloc, MAX_ALGORITHM_NAME_LEN, MD5_PASSWD_LEN, pg_fe_scram_build_secret(), pg_md5_encrypt(), PGRES_TUPLES_OK, PQclear(), pqClearConnErrorState, PQexec(), PQgetvalue(), PQnfields(), PQntuples(), PQresultStatus(), res, pg_conn::scram_sha_256_iterations, user, and val.

Referenced by exec_command_password(), and main().