/*------------------------------------------------------------------------- * * fe-auth.c * The front-end (client) authorization routines * * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION * src/interfaces/libpq/fe-auth.c * *------------------------------------------------------------------------- */ /* * INTERFACE ROUTINES * frontend (client) routines: * pg_fe_sendauth send authentication information * pg_fe_getauthname get user's name according to the client side * of the authentication system */ #include "postgres_fe.h" #ifdef WIN32 #include "win32.h" #else #include #include #include #include #include /* for MAXHOSTNAMELEN on most */ #include #ifdef HAVE_SYS_UCRED_H #include #endif #ifndef MAXHOSTNAMELEN #include /* for MAXHOSTNAMELEN on some */ #endif #endif #include "common/md5.h" #include "common/oauth-common.h" #include "common/scram-common.h" #include "fe-auth.h" #include "fe-auth-sasl.h" #include "fe-auth-oauth.h" #include "libpq-fe.h" #ifdef ENABLE_GSS /* * GSSAPI authentication system. */ #include "fe-gssapi-common.h" /* * Continue GSS authentication with next token as needed. */ static int pg_GSS_continue(PGconn *conn, int payloadlen) { OM_uint32 maj_stat, min_stat, lmin_s, gss_flags = GSS_C_MUTUAL_FLAG; gss_buffer_desc ginbuf; gss_buffer_desc goutbuf; /* * On first call, there's no input token. On subsequent calls, read the * input token into a GSS buffer. */ if (conn->gctx != GSS_C_NO_CONTEXT) { ginbuf.length = payloadlen; ginbuf.value = malloc(payloadlen); if (!ginbuf.value) { libpq_append_conn_error(conn, "out of memory allocating GSSAPI buffer (%d)", payloadlen); return STATUS_ERROR; } if (pqGetnchar(ginbuf.value, payloadlen, conn)) { /* * Shouldn't happen, because the caller should've ensured that the * whole message is already in the input buffer. */ free(ginbuf.value); return STATUS_ERROR; } } else { ginbuf.length = 0; ginbuf.value = NULL; } /* finished parsing, trace server-to-client message */ if (conn->Pfdebug) pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false); /* Only try to acquire credentials if GSS delegation isn't disabled. */ if (!pg_GSS_have_cred_cache(&conn->gcred)) conn->gcred = GSS_C_NO_CREDENTIAL; if (conn->gssdelegation && conn->gssdelegation[0] == '1') gss_flags |= GSS_C_DELEG_FLAG; maj_stat = gss_init_sec_context(&min_stat, conn->gcred, &conn->gctx, conn->gtarg_nam, GSS_C_NO_OID, gss_flags, 0, GSS_C_NO_CHANNEL_BINDINGS, (ginbuf.value == NULL) ? GSS_C_NO_BUFFER : &ginbuf, NULL, &goutbuf, NULL, NULL); free(ginbuf.value); if (goutbuf.length != 0) { /* * GSS generated data to send to the server. We don't care if it's the * first or subsequent packet, just send the same kind of password * packet. */ conn->current_auth_response = AUTH_RESPONSE_GSS; if (pqPacketSend(conn, PqMsg_GSSResponse, goutbuf.value, goutbuf.length) != STATUS_OK) { gss_release_buffer(&lmin_s, &goutbuf); return STATUS_ERROR; } } gss_release_buffer(&lmin_s, &goutbuf); if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED) { pg_GSS_error(libpq_gettext("GSSAPI continuation error"), conn, maj_stat, min_stat); gss_release_name(&lmin_s, &conn->gtarg_nam); if (conn->gctx) gss_delete_sec_context(&lmin_s, &conn->gctx, GSS_C_NO_BUFFER); return STATUS_ERROR; } if (maj_stat == GSS_S_COMPLETE) { conn->client_finished_auth = true; gss_release_name(&lmin_s, &conn->gtarg_nam); conn->gssapi_used = true; } return STATUS_OK; } /* * Send initial GSS authentication token */ static int pg_GSS_startup(PGconn *conn, int payloadlen) { int ret; char *host = conn->connhost[conn->whichhost].host; if (!(host && host[0] != '\0')) { libpq_append_conn_error(conn, "host name must be specified"); return STATUS_ERROR; } if (conn->gctx) { libpq_append_conn_error(conn, "duplicate GSS authentication request"); return STATUS_ERROR; } ret = pg_GSS_load_servicename(conn); if (ret != STATUS_OK) return ret; /* * Initial packet is the same as a continuation packet with no initial * context. */ conn->gctx = GSS_C_NO_CONTEXT; return pg_GSS_continue(conn, payloadlen); } #endif /* ENABLE_GSS */ #ifdef ENABLE_SSPI /* * SSPI authentication system (Windows only) */ static void pg_SSPI_error(PGconn *conn, const char *mprefix, SECURITY_STATUS r) { char sysmsg[256]; if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM, NULL, r, 0, sysmsg, sizeof(sysmsg), NULL) == 0) appendPQExpBuffer(&conn->errorMessage, "%s: SSPI error %x\n", mprefix, (unsigned int) r); else appendPQExpBuffer(&conn->errorMessage, "%s: %s (%x)\n", mprefix, sysmsg, (unsigned int) r); } /* * Continue SSPI authentication with next token as needed. */ static int pg_SSPI_continue(PGconn *conn, int payloadlen) { SECURITY_STATUS r; CtxtHandle newContext; ULONG contextAttr; SecBufferDesc inbuf; SecBufferDesc outbuf; SecBuffer OutBuffers[1]; SecBuffer InBuffers[1]; char *inputbuf = NULL; if (conn->sspictx != NULL) { /* * On runs other than the first we have some data to send. Put this * data in a SecBuffer type structure. */ inputbuf = malloc(payloadlen); if (!inputbuf) { libpq_append_conn_error(conn, "out of memory allocating SSPI buffer (%d)", payloadlen); return STATUS_ERROR; } if (pqGetnchar(inputbuf, payloadlen, conn)) { /* * Shouldn't happen, because the caller should've ensured that the * whole message is already in the input buffer. */ free(inputbuf); return STATUS_ERROR; } inbuf.ulVersion = SECBUFFER_VERSION; inbuf.cBuffers = 1; inbuf.pBuffers = InBuffers; InBuffers[0].pvBuffer = inputbuf; InBuffers[0].cbBuffer = payloadlen; InBuffers[0].BufferType = SECBUFFER_TOKEN; } /* finished parsing, trace server-to-client message */ if (conn->Pfdebug) pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false); OutBuffers[0].pvBuffer = NULL; OutBuffers[0].BufferType = SECBUFFER_TOKEN; OutBuffers[0].cbBuffer = 0; outbuf.cBuffers = 1; outbuf.pBuffers = OutBuffers; outbuf.ulVersion = SECBUFFER_VERSION; r = InitializeSecurityContext(conn->sspicred, conn->sspictx, conn->sspitarget, ISC_REQ_ALLOCATE_MEMORY, 0, SECURITY_NETWORK_DREP, (conn->sspictx == NULL) ? NULL : &inbuf, 0, &newContext, &outbuf, &contextAttr, NULL); /* we don't need the input anymore */ free(inputbuf); if (r != SEC_E_OK && r != SEC_I_CONTINUE_NEEDED) { pg_SSPI_error(conn, libpq_gettext("SSPI continuation error"), r); return STATUS_ERROR; } if (conn->sspictx == NULL) { /* On first run, transfer retrieved context handle */ conn->sspictx = malloc(sizeof(CtxtHandle)); if (conn->sspictx == NULL) { libpq_append_conn_error(conn, "out of memory"); return STATUS_ERROR; } memcpy(conn->sspictx, &newContext, sizeof(CtxtHandle)); } /* * If SSPI returned any data to be sent to the server (as it normally * would), send this data as a password packet. */ if (outbuf.cBuffers > 0) { if (outbuf.cBuffers != 1) { /* * This should never happen, at least not for Kerberos * authentication. Keep check in case it shows up with other * authentication methods later. */ appendPQExpBufferStr(&conn->errorMessage, "SSPI returned invalid number of output buffers\n"); return STATUS_ERROR; } /* * If the negotiation is complete, there may be zero bytes to send. * The server is at this point not expecting any more data, so don't * send it. */ if (outbuf.pBuffers[0].cbBuffer > 0) { conn->current_auth_response = AUTH_RESPONSE_GSS; if (pqPacketSend(conn, PqMsg_GSSResponse, outbuf.pBuffers[0].pvBuffer, outbuf.pBuffers[0].cbBuffer)) { FreeContextBuffer(outbuf.pBuffers[0].pvBuffer); return STATUS_ERROR; } } FreeContextBuffer(outbuf.pBuffers[0].pvBuffer); } if (r == SEC_E_OK) conn->client_finished_auth = true; /* Cleanup is handled by the code in freePGconn() */ return STATUS_OK; } /* * Send initial SSPI authentication token. * If use_negotiate is 0, use kerberos authentication package which is * compatible with Unix. If use_negotiate is 1, use the negotiate package * which supports both kerberos and NTLM, but is not compatible with Unix. */ static int pg_SSPI_startup(PGconn *conn, int use_negotiate, int payloadlen) { SECURITY_STATUS r; TimeStamp expire; char *host = conn->connhost[conn->whichhost].host; if (conn->sspictx) { libpq_append_conn_error(conn, "duplicate SSPI authentication request"); return STATUS_ERROR; } /* * Retrieve credentials handle */ conn->sspicred = malloc(sizeof(CredHandle)); if (conn->sspicred == NULL) { libpq_append_conn_error(conn, "out of memory"); return STATUS_ERROR; } r = AcquireCredentialsHandle(NULL, use_negotiate ? "negotiate" : "kerberos", SECPKG_CRED_OUTBOUND, NULL, NULL, NULL, NULL, conn->sspicred, &expire); if (r != SEC_E_OK) { pg_SSPI_error(conn, libpq_gettext("could not acquire SSPI credentials"), r); free(conn->sspicred); conn->sspicred = NULL; return STATUS_ERROR; } /* * Compute target principal name. SSPI has a different format from GSSAPI, * but not more complex. We can skip the @REALM part, because Windows will * fill that in for us automatically. */ if (!(host && host[0] != '\0')) { libpq_append_conn_error(conn, "host name must be specified"); return STATUS_ERROR; } conn->sspitarget = malloc(strlen(conn->krbsrvname) + strlen(host) + 2); if (!conn->sspitarget) { libpq_append_conn_error(conn, "out of memory"); return STATUS_ERROR; } sprintf(conn->sspitarget, "%s/%s", conn->krbsrvname, host); /* * Indicate that we're in SSPI authentication mode to make sure that * pg_SSPI_continue is called next time in the negotiation. */ conn->usesspi = 1; return pg_SSPI_continue(conn, payloadlen); } #endif /* ENABLE_SSPI */ /* * Initialize SASL authentication exchange. */ static int pg_SASL_init(PGconn *conn, int payloadlen, bool *async) { char *initialresponse = NULL; int initialresponselen; const char *selected_mechanism; PQExpBufferData mechanism_buf; char *password = NULL; SASLStatus status; 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 && !conn->async_auth) { 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. Mechanisms are 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; conn->password_needed = true; } #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; conn->password_needed = true; } else if (strcmp(mechanism_buf.data, OAUTHBEARER_NAME) == 0 && !selected_mechanism) { selected_mechanism = OAUTHBEARER_NAME; conn->sasl = &pg_oauth_mech; conn->password_needed = false; } } if (!selected_mechanism) { libpq_append_conn_error(conn, "none of the server's SASL authentication mechanisms are supported"); goto error; } /* Make sure require_auth is satisfied. */ if (conn->require_auth) { bool allowed = false; for (int i = 0; i < lengthof(conn->allowed_sasl_mechs); i++) { if (conn->sasl == conn->allowed_sasl_mechs[i]) { allowed = true; break; } } if (!allowed) { libpq_append_conn_error(conn, "authentication method requirement \"%s\" failed: server requested %s authentication", conn->require_auth, selected_mechanism); 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 and the selected SASL mechanism needs it. */ if (conn->password_needed && !conn->scram_client_key_binary) { password = conn->connhost[conn->whichhost].password; if (password == NULL) password = conn->pgpass; if (password == NULL || password[0] == '\0') { appendPQExpBufferStr(&conn->errorMessage, PQnoPasswordSupplied); goto error; } } /* finished parsing, trace server-to-client message */ if (conn->Pfdebug) pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false); Assert(conn->sasl); if (!conn->sasl_state) { /* * 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; } else { /* * This is only possible if we're returning from an async loop. * Disconnect it now. */ Assert(conn->async_auth); conn->async_auth = NULL; } /* Get the mechanism-specific Initial Client Response, if any */ status = conn->sasl->exchange(conn->sasl_state, false, NULL, -1, &initialresponse, &initialresponselen); if (status == SASL_FAILED) goto error; if (status == SASL_ASYNC) { /* * The mechanism should have set up the necessary callbacks; all we * need to do is signal the caller. * * In non-assertion builds, this postcondition is enforced at time of * use in PQconnectPoll(). */ Assert(conn->async_auth); Assert(conn->cleanup_async_auth); *async = true; return STATUS_OK; } /* * 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; } conn->current_auth_response = AUTH_RESPONSE_SASL_INITIAL; 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; } /* * Exchange a message for SASL communication protocol with the backend. * This should be used after calling pg_SASL_init to set up the status of * the protocol. */ static int pg_SASL_continue(PGconn *conn, int payloadlen, bool final, bool *async) { char *output; int outputlen; int res; char *challenge; SASLStatus status; /* 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; } /* finished parsing, trace server-to-client message */ if (conn->Pfdebug) pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false); /* For safety and convenience, ensure the buffer is NULL-terminated. */ challenge[payloadlen] = '\0'; status = conn->sasl->exchange(conn->sasl_state, final, challenge, payloadlen, &output, &outputlen); free(challenge); /* don't need the input anymore */ if (status == SASL_ASYNC) { /* * The mechanism should have set up the necessary callbacks; all we * need to do is signal the caller. */ *async = true; /* * The mechanism may optionally generate some output to send before * switching over to async auth, so continue onwards. */ } if (final && status == SASL_CONTINUE) { 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 && status == SASL_CONTINUE) { 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. */ conn->current_auth_response = AUTH_RESPONSE_SASL; res = pqPacketSend(conn, PqMsg_SASLResponse, output, outputlen); free(output); if (res != STATUS_OK) return STATUS_ERROR; } if (status == SASL_FAILED) return STATUS_ERROR; return STATUS_OK; } static int pg_password_sendauth(PGconn *conn, const char *password, AuthRequest areq) { int ret; char *crypt_pwd = NULL; const char *pwd_to_send; uint8 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 */ } /* finished parsing, trace server-to-client message */ if (conn->Pfdebug) pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false); /* 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, (uint8 *) 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; } conn->current_auth_response = AUTH_RESPONSE_PASSWORD; ret = pqPacketSend(conn, PqMsg_PasswordMessage, pwd_to_send, strlen(pwd_to_send) + 1); free(crypt_pwd); return ret; } /* * Translate a disallowed AuthRequest code into an error message. */ static const char * auth_method_description(AuthRequest areq) { 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"); } /* * Convenience macro for checking the allowed_auth_methods bitmask. Caller * must ensure that type is not greater than 31 (high bit of the bitmask). */ #define auth_method_allowed(conn, type) \ (((conn)->allowed_auth_methods & (1 << (type))) != 0) /* * Verify that the authentication request is expected, given the connection * parameters. This is especially important when the client wishes to * authenticate the server before any sensitive information is exchanged. */ static bool check_expected_areq(AuthRequest areq, PGconn *conn) { 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; } /* * pg_fe_sendauth * client demux routine for processing an authentication request * * The server has sent us an authentication challenge (or OK). Send an * appropriate response. The caller has ensured that the whole message is * now in the input buffer, and has already read the type and length of * it. We are responsible for reading any remaining extra data, specific * to the authentication method. 'payloadlen' is the remaining length in * the message. * * If *async is set to true on return, the client doesn't yet have enough * information to respond, and the caller must temporarily switch to * conn->async_auth() to continue driving the exchange. */ int pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn, bool *async) { int oldmsglen; *async = false; 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, async) != STATUS_OK) { /* pg_SASL_init already set the error message */ return STATUS_ERROR; } break; case AUTH_REQ_SASL_CONT: case AUTH_REQ_SASL_FIN: { bool final = false; 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 (areq == AUTH_REQ_SASL_FIN) final = true; if (pg_SASL_continue(conn, payloadlen, final, async) != STATUS_OK) { /* * Append a generic error message unless pg_SASL_continue * did set a more specific one already. */ 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; } /* * pg_fe_getusername * * Returns a pointer to malloc'd space containing the name of the * specified user_id. If there is an error, return NULL, and append * a suitable error message to *errorMessage if that's not NULL. * * Caution: on Windows, the user_id argument is ignored, and we always * fetch the current user's name. */ char * pg_fe_getusername(uid_t user_id, PQExpBuffer errorMessage) { 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 struct passwd pwbuf; struct passwd *pw = NULL; char buf[1024]; int rc; #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 rc = getpwuid_r(user_id, &pwbuf, buf, sizeof buf, &pw); if (rc != 0) { errno = rc; if (errorMessage) libpq_append_error(errorMessage, "could not look up local user ID %ld: %m", (long) user_id); } else if (!pw) { if (errorMessage) libpq_append_error(errorMessage, "local user with ID %ld does not exist", (long) user_id); } else name = pw->pw_name; #endif if (name) { result = strdup(name); if (result == NULL && errorMessage) libpq_append_error(errorMessage, "out of memory"); } return result; } /* * pg_fe_getauthname * * Returns a pointer to malloc'd space containing whatever name the user * has authenticated to the system. If there is an error, return NULL, * and append a suitable error message to *errorMessage if that's not NULL. */ char * pg_fe_getauthname(PQExpBuffer errorMessage) { #ifdef WIN32 return pg_fe_getusername(0, errorMessage); #else return pg_fe_getusername(geteuid(), errorMessage); #endif } /* * PQencryptPassword -- exported routine to encrypt a password with MD5 * * This function is equivalent to calling PQencryptPasswordConn with * "md5" as the encryption method, except that this doesn't require * a connection object. This function is deprecated, use * PQencryptPasswordConn instead. */ char * PQencryptPassword(const char *passwd, const char *user) { char *crypt_pwd; const char *errstr = NULL; crypt_pwd = malloc(MD5_PASSWD_LEN + 1); if (!crypt_pwd) return NULL; if (!pg_md5_encrypt(passwd, (uint8 *) user, strlen(user), crypt_pwd, &errstr)) { free(crypt_pwd); return NULL; } return crypt_pwd; } /* * PQencryptPasswordConn -- exported routine to encrypt a password * * This is intended to be used by client applications that wish to send * commands like ALTER USER joe PASSWORD 'pwd'. The password need not * be sent in cleartext if it is encrypted on the client side. This is * good because it ensures the cleartext password won't end up in logs, * pg_stat displays, etc. We export the function so that clients won't * be dependent on low-level details like whether the encryption is MD5 * or something else. * * Arguments are a connection object, the cleartext password, the SQL * name of the user it is for, and a string indicating the algorithm to * use for encrypting the password. If algorithm is NULL, this queries * the server for the current 'password_encryption' value. If you wish * to avoid that, e.g. to avoid blocking, you can execute * 'show password_encryption' yourself before calling this function, and * pass it as the algorithm. * * Return value is a malloc'd string. The client may assume the string * doesn't contain any special characters that would require escaping. * On error, an error message is stored in the connection object, and * returns NULL. */ char * PQencryptPasswordConn(PGconn *conn, const char *passwd, const char *user, const char *algorithm) { #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, (uint8 *) 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; } /* * PQchangePassword -- exported routine to change a password * * This is intended to be used by client applications that wish to * change the password for a user. The password is not sent in * cleartext because it is encrypted on the client side. This is * good because it ensures the cleartext password is never known by * the server, and therefore won't end up in logs, pg_stat displays, * etc. The password encryption is performed by PQencryptPasswordConn(), * which is passed a NULL for the algorithm argument. Hence encryption * is done according to the server's password_encryption * setting. We export the function so that clients won't be dependent * on the implementation specific details with respect to how the * server changes passwords. * * Arguments are a connection object, the SQL name of the target user, * and the cleartext password. * * Return value is the PGresult of the executed ALTER USER statement * or NULL if we never get there. The caller is responsible to PQclear() * the returned PGresult. * * PQresultStatus() should be called to check the return value for errors, * and PQerrorMessage() used to get more information about such errors. */ PGresult * PQchangePassword(PGconn *conn, const char *user, const char *passwd) { char *encrypted_password = PQencryptPasswordConn(conn, passwd, user, NULL); if (!encrypted_password) { /* PQencryptPasswordConn() already registered the error */ return NULL; } else { char *fmtpw = PQescapeLiteral(conn, encrypted_password, strlen(encrypted_password)); /* no longer needed, so clean up now */ PQfreemem(encrypted_password); if (!fmtpw) { /* PQescapeLiteral() already registered the error */ return NULL; } else { char *fmtuser = PQescapeIdentifier(conn, user, strlen(user)); if (!fmtuser) { /* PQescapeIdentifier() already registered the error */ PQfreemem(fmtpw); return NULL; } else { PQExpBufferData buf; PGresult *res; initPQExpBuffer(&buf); printfPQExpBuffer(&buf, "ALTER USER %s PASSWORD %s", fmtuser, fmtpw); res = PQexec(conn, buf.data); /* clean up */ termPQExpBuffer(&buf); PQfreemem(fmtuser); PQfreemem(fmtpw); return res; } } } } PQauthDataHook_type PQauthDataHook = PQdefaultAuthDataHook; PQauthDataHook_type PQgetAuthDataHook(void) { return PQauthDataHook; } void PQsetAuthDataHook(PQauthDataHook_type hook) { PQauthDataHook = hook ? hook : PQdefaultAuthDataHook; } int PQdefaultAuthDataHook(PGauthData type, PGconn *conn, void *data) { return 0; /* handle nothing */ }