/*------------------------------------------------------------------------- * * auth.c * Routines to handle network authentication * * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $Header: /cvsroot/pgsql/src/backend/libpq/auth.c,v 1.52 2001/03/22 03:59:30 momjian Exp $ * *------------------------------------------------------------------------- */ /* * INTERFACE ROUTINES * * backend (postmaster) routines: * be_recvauth receive authentication information */ #include /* for MAXHOSTNAMELEN on most */ #ifndef MAXHOSTNAMELEN #include /* for MAXHOSTNAMELEN on some */ #endif #include #include #include /* needed by in.h on Ultrix */ #include #include #include "postgres.h" #include "libpq/auth.h" #include "libpq/crypt.h" #include "libpq/hba.h" #include "libpq/libpq.h" #include "libpq/password.h" #include "miscadmin.h" static void sendAuthRequest(Port *port, AuthRequest areq, PacketDoneProc handler); static int handle_done_auth(void *arg, PacketLen len, void *pkt); static int handle_krb4_auth(void *arg, PacketLen len, void *pkt); static int handle_krb5_auth(void *arg, PacketLen len, void *pkt); static int handle_password_auth(void *arg, PacketLen len, void *pkt); static int readPasswordPacket(void *arg, PacketLen len, void *pkt); static int pg_passwordv0_recvauth(void *arg, PacketLen len, void *pkt); static int checkPassword(Port *port, char *user, char *password); static int old_be_recvauth(Port *port); static int map_old_to_new(Port *port, UserAuth old, int status); static void auth_failed(Port *port); char *pg_krb_server_keyfile; #ifdef KRB4 /*---------------------------------------------------------------- * MIT Kerberos authentication system - protocol version 4 *---------------------------------------------------------------- */ #include "krb.h" /* * pg_krb4_recvauth -- server routine to receive authentication information * from the client * * Nothing unusual here, except that we compare the username obtained from * the client's setup packet to the authenticated name. (We have to retain * the name in the setup packet since we have to retain the ability to handle * unauthenticated connections.) */ static int pg_krb4_recvauth(Port *port) { long krbopts = 0; /* one-way authentication */ KTEXT_ST clttkt; char instance[INST_SZ + 1], version[KRB_SENDAUTH_VLEN + 1]; AUTH_DAT auth_data; Key_schedule key_sched; int status; strcpy(instance, "*"); /* don't care, but arg gets expanded * anyway */ status = krb_recvauth(krbopts, port->sock, &clttkt, PG_KRB_SRVNAM, instance, &port->raddr.in, &port->laddr.in, &auth_data, pg_krb_server_keyfile, key_sched, version); if (status != KSUCCESS) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_krb4_recvauth: kerberos error: %s\n", krb_err_txt[status]); fputs(PQerrormsg, stderr); pqdebug("%s", PQerrormsg); return STATUS_ERROR; } if (strncmp(version, PG_KRB4_VERSION, KRB_SENDAUTH_VLEN)) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_krb4_recvauth: protocol version != \"%s\"\n", PG_KRB4_VERSION); fputs(PQerrormsg, stderr); pqdebug("%s", PQerrormsg); return STATUS_ERROR; } if (strncmp(port->user, auth_data.pname, SM_USER)) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_krb4_recvauth: name \"%s\" != \"%s\"\n", port->user, auth_data.pname); fputs(PQerrormsg, stderr); pqdebug("%s", PQerrormsg); return STATUS_ERROR; } return STATUS_OK; } #else static int pg_krb4_recvauth(Port *port) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_krb4_recvauth: Kerberos not implemented on this server.\n"); fputs(PQerrormsg, stderr); pqdebug("%s", PQerrormsg); return STATUS_ERROR; } #endif /* KRB4 */ #ifdef KRB5 /*---------------------------------------------------------------- * MIT Kerberos authentication system - protocol version 5 *---------------------------------------------------------------- */ #include #include /* * pg_an_to_ln -- return the local name corresponding to an authentication * name * * XXX Assumes that the first aname component is the user name. This is NOT * necessarily so, since an aname can actually be something out of your * worst X.400 nightmare, like * ORGANIZATION=U. C. Berkeley/NAME=Paul M. Aoki@CS.BERKELEY.EDU * Note that the MIT an_to_ln code does the same thing if you don't * provide an aname mapping database...it may be a better idea to use * krb5_an_to_ln, except that it punts if multiple components are found, * and we can't afford to punt. */ static char * pg_an_to_ln(char *aname) { char *p; if ((p = strchr(aname, '/')) || (p = strchr(aname, '@'))) *p = '\0'; return aname; } /* * Various krb5 state which is not connection specfic, and a flag to * indicate whether we have initialised it yet. */ static int pg_krb5_initialised; static krb5_context pg_krb5_context; static krb5_keytab pg_krb5_keytab; static krb5_principal pg_krb5_server; static int pg_krb5_init(void) { krb5_error_code retval; if (pg_krb5_initialised) return STATUS_OK; retval = krb5_init_context(&pg_krb5_context); if (retval) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_krb5_init: krb5_init_context returned" " Kerberos error %d\n", retval); com_err("postgres", retval, "while initializing krb5"); return STATUS_ERROR; } retval = krb5_kt_resolve(pg_krb5_context, pg_krb_server_keyfile, &pg_krb5_keytab); if (retval) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_krb5_init: krb5_kt_resolve returned" " Kerberos error %d\n", retval); com_err("postgres", retval, "while resolving keytab file %s", pg_krb_server_keyfile); krb5_free_context(pg_krb5_context); return STATUS_ERROR; } retval = krb5_sname_to_principal(pg_krb5_context, NULL, PG_KRB_SRVNAM, KRB5_NT_SRV_HST, &pg_krb5_server); if (retval) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_krb5_init: krb5_sname_to_principal returned" " Kerberos error %d\n", retval); com_err("postgres", retval, "while getting server principal for service %s", pg_krb_server_keyfile); krb5_kt_close(pg_krb5_context, pg_krb5_keytab); krb5_free_context(pg_krb5_context); return STATUS_ERROR; } pg_krb5_initialised = 1; return STATUS_OK; } /* * pg_krb5_recvauth -- server routine to receive authentication information * from the client * * We still need to compare the username obtained from the client's setup * packet to the authenticated name, as described in pg_krb4_recvauth. This * is a bit more problematic in v5, as described above in pg_an_to_ln. * * We have our own keytab file because postgres is unlikely to run as root, * and so cannot read the default keytab. */ static int pg_krb5_recvauth(Port *port) { krb5_error_code retval; int ret; krb5_auth_context auth_context = NULL; krb5_ticket *ticket; char *kusername; ret = pg_krb5_init(); if (ret != STATUS_OK) return ret; retval = krb5_recvauth(pg_krb5_context, &auth_context, (krb5_pointer) & port->sock, PG_KRB_SRVNAM, pg_krb5_server, 0, pg_krb5_keytab, &ticket); if (retval) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_krb5_recvauth: krb5_recvauth returned" " Kerberos error %d\n", retval); com_err("postgres", retval, "from krb5_recvauth"); return STATUS_ERROR; } /* * The "client" structure comes out of the ticket and is therefore * authenticated. Use it to check the username obtained from the * postmaster startup packet. * * I have no idea why this is considered necessary. */ retval = krb5_unparse_name(pg_krb5_context, ticket->enc_part2->client, &kusername); if (retval) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_krb5_recvauth: krb5_unparse_name returned" " Kerberos error %d\n", retval); com_err("postgres", retval, "while unparsing client name"); krb5_free_ticket(pg_krb5_context, ticket); krb5_auth_con_free(pg_krb5_context, auth_context); return STATUS_ERROR; } kusername = pg_an_to_ln(kusername); if (strncmp(port->user, kusername, SM_USER)) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_krb5_recvauth: user name \"%s\" != krb5 name \"%s\"\n", port->user, kusername); ret = STATUS_ERROR; } else ret = STATUS_OK; krb5_free_ticket(pg_krb5_context, ticket); krb5_auth_con_free(pg_krb5_context, auth_context); free(kusername); return ret; } #else static int pg_krb5_recvauth(Port *port) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_krb5_recvauth: Kerberos not implemented on this server.\n"); fputs(PQerrormsg, stderr); pqdebug("%s", PQerrormsg); return STATUS_ERROR; } #endif /* KRB5 */ /* * Handle a v0 password packet. */ static int pg_passwordv0_recvauth(void *arg, PacketLen len, void *pkt) { Port *port; PasswordPacketV0 *pp; char *user, *password, *cp, *start; port = (Port *) arg; pp = (PasswordPacketV0 *) pkt; /* * The packet is supposed to comprise the user name and the password * as C strings. Be careful the check that this is the case. */ user = password = NULL; len -= sizeof(pp->unused); cp = start = pp->data; while (len-- > 0) if (*cp++ == '\0') { if (user == NULL) user = start; else { password = start; break; } start = cp; } if (user == NULL || password == NULL) { snprintf(PQerrormsg, PQERRORMSG_LENGTH, "pg_password_recvauth: badly formed password packet.\n"); fputs(PQerrormsg, stderr); pqdebug("%s", PQerrormsg); auth_failed(port); } else { int status; UserAuth saved; /* Check the password. */ saved = port->auth_method; port->auth_method = uaPassword; status = checkPassword(port, user, password); port->auth_method = saved; /* Adjust the result if necessary. */ if (map_old_to_new(port, uaPassword, status) != STATUS_OK) auth_failed(port); } return STATUS_OK; /* don't close the connection yet */ } /* * Tell the user the authentication failed, but not (much about) why. * * There is a tradeoff here between security concerns and making life * unnecessarily difficult for legitimate users. We would not, for example, * want to report the password we were expecting to receive... * But it seems useful to report the username and authorization method * in use, and these are items that must be presumed known to an attacker * anyway. * Note that many sorts of failure report additional information in the * postmaster log, which we hope is only readable by good guys. */ static void auth_failed(Port *port) { char buffer[512]; const char *authmethod = "Unknown auth method:"; switch (port->auth_method) { case uaReject: authmethod = "Rejected host:"; break; case uaKrb4: authmethod = "Kerberos4"; break; case uaKrb5: authmethod = "Kerberos5"; break; case uaTrust: authmethod = "Trusted"; break; case uaIdent: authmethod = "IDENT"; break; case uaPassword: authmethod = "Password"; break; case uaCrypt: authmethod = "Password"; break; } sprintf(buffer, "%s authentication failed for user '%s'", authmethod, port->user); PacketSendError(&port->pktInfo, buffer); } /* * be_recvauth -- server demux routine for incoming authentication information */ void be_recvauth(Port *port) { /* * Get the authentication method to use for this frontend/database * combination. Note: a failure return indicates a problem with the * hba config file, not with the request. hba.c should have dropped * an error message into the postmaster logfile if it failed. */ if (hba_getauthmethod(port) != STATUS_OK) PacketSendError(&port->pktInfo, "Missing or erroneous pg_hba.conf file, see postmaster log for details"); else if (PG_PROTOCOL_MAJOR(port->proto) == 0) { /* Handle old style authentication. */ if (old_be_recvauth(port) != STATUS_OK) auth_failed(port); } else { /* Handle new style authentication. */ AuthRequest areq = AUTH_REQ_OK; PacketDoneProc auth_handler = NULL; switch (port->auth_method) { case uaReject: /* * This could have come from an explicit "reject" entry in * pg_hba.conf, but more likely it means there was no * matching entry. Take pity on the poor user and issue a * helpful error message. NOTE: this is not a security * breach, because all the info reported here is known at * the frontend and must be assumed known to bad guys. * We're merely helping out the less clueful good guys. * NOTE 2: libpq-be.h defines the maximum error message * length as 99 characters. It probably wouldn't hurt * anything to increase it, but there might be some client * out there that will fail. So, be terse. */ { char buffer[512]; const char *hostinfo = "localhost"; if (port->raddr.sa.sa_family == AF_INET) hostinfo = inet_ntoa(port->raddr.in.sin_addr); sprintf(buffer, "No pg_hba.conf entry for host %s, user %s, database %s", hostinfo, port->user, port->database); PacketSendError(&port->pktInfo, buffer); return; } break; case uaKrb4: areq = AUTH_REQ_KRB4; auth_handler = handle_krb4_auth; break; case uaKrb5: areq = AUTH_REQ_KRB5; auth_handler = handle_krb5_auth; break; case uaTrust: areq = AUTH_REQ_OK; auth_handler = handle_done_auth; break; case uaIdent: if (authident(&port->raddr.in, &port->laddr.in, port->user, port->auth_arg) == STATUS_OK) { areq = AUTH_REQ_OK; auth_handler = handle_done_auth; } break; case uaPassword: areq = AUTH_REQ_PASSWORD; auth_handler = handle_password_auth; break; case uaCrypt: areq = AUTH_REQ_CRYPT; auth_handler = handle_password_auth; break; } /* Tell the frontend what we want next. */ if (auth_handler != NULL) sendAuthRequest(port, areq, auth_handler); else auth_failed(port); } } /* * Send an authentication request packet to the frontend. */ static void sendAuthRequest(Port *port, AuthRequest areq, PacketDoneProc handler) { char *dp, *sp; int i; uint32 net_areq; /* Convert to a byte stream. */ net_areq = htonl(areq); dp = port->pktInfo.pkt.ar.data; sp = (char *) &net_areq; *dp++ = 'R'; for (i = 1; i <= 4; ++i) *dp++ = *sp++; /* Add the salt for encrypted passwords. */ if (areq == AUTH_REQ_CRYPT) { *dp++ = port->salt[0]; *dp++ = port->salt[1]; i += 2; } PacketSendSetup(&port->pktInfo, i, handler, (void *) port); } /* * Called when we have told the front end that it is authorised. */ static int handle_done_auth(void *arg, PacketLen len, void *pkt) { /* * Don't generate any more traffic. This will cause the backend to * start. */ return STATUS_OK; } /* * Called when we have told the front end that it should use Kerberos V4 * authentication. */ static int handle_krb4_auth(void *arg, PacketLen len, void *pkt) { Port *port = (Port *) arg; if (pg_krb4_recvauth(port) != STATUS_OK) auth_failed(port); else sendAuthRequest(port, AUTH_REQ_OK, handle_done_auth); return STATUS_OK; } /* * Called when we have told the front end that it should use Kerberos V5 * authentication. */ static int handle_krb5_auth(void *arg, PacketLen len, void *pkt) { Port *port = (Port *) arg; if (pg_krb5_recvauth(port) != STATUS_OK) auth_failed(port); else sendAuthRequest(port, AUTH_REQ_OK, handle_done_auth); return STATUS_OK; } /* * Called when we have told the front end that it should use password * authentication. */ static int handle_password_auth(void *arg, PacketLen len, void *pkt) { Port *port = (Port *) arg; /* Set up the read of the password packet. */ PacketReceiveSetup(&port->pktInfo, readPasswordPacket, (void *) port); return STATUS_OK; } /* * Called when we have received the password packet. */ static int readPasswordPacket(void *arg, PacketLen len, void *pkt) { char password[sizeof(PasswordPacket) + 1]; Port *port = (Port *) arg; /* Silently truncate a password that is too big. */ if (len > sizeof(PasswordPacket)) len = sizeof(PasswordPacket); StrNCpy(password, ((PasswordPacket *) pkt)->passwd, len); if (checkPassword(port, port->user, password) != STATUS_OK) auth_failed(port); else sendAuthRequest(port, AUTH_REQ_OK, handle_done_auth); return STATUS_OK; /* don't close the connection yet */ } /* * Handle `password' and `crypt' records. If an auth argument was * specified, use the respective file. Else use pg_shadow passwords. */ static int checkPassword(Port *port, char *user, char *password) { if (port->auth_arg[0] != '\0') return verify_password(port, user, password); return crypt_verify(port, user, password); } /* * Server demux routine for incoming authentication information for protocol * version 0. */ static int old_be_recvauth(Port *port) { int status; MsgType msgtype = (MsgType) port->proto; /* Handle the authentication that's offered. */ switch (msgtype) { case STARTUP_KRB4_MSG: status = map_old_to_new(port, uaKrb4, pg_krb4_recvauth(port)); break; case STARTUP_KRB5_MSG: status = map_old_to_new(port, uaKrb5, pg_krb5_recvauth(port)); break; case STARTUP_MSG: status = map_old_to_new(port, uaTrust, STATUS_OK); break; case STARTUP_PASSWORD_MSG: PacketReceiveSetup(&port->pktInfo, pg_passwordv0_recvauth, (void *) port); return STATUS_OK; default: fprintf(stderr, "Invalid startup message type: %u\n", msgtype); return STATUS_OK; } return status; } /* * The old style authentication has been done. Modify the result of this (eg. * allow the connection anyway, disallow it anyway, or use the result) * depending on what authentication we really want to use. */ static int map_old_to_new(Port *port, UserAuth old, int status) { switch (port->auth_method) { case uaCrypt: case uaReject: status = STATUS_ERROR; break; case uaKrb4: if (old != uaKrb4) status = STATUS_ERROR; break; case uaKrb5: if (old != uaKrb5) status = STATUS_ERROR; break; case uaTrust: status = STATUS_OK; break; case uaIdent: status = authident(&port->raddr.in, &port->laddr.in, port->user, port->auth_arg); break; case uaPassword: if (old != uaPassword) status = STATUS_ERROR; break; } return status; }