diff options
Diffstat (limited to 'src/interfaces/libpq/fe-auth.c')
| -rw-r--r-- | src/interfaces/libpq/fe-auth.c | 1285 |
1 files changed, 1285 insertions, 0 deletions
diff --git a/src/interfaces/libpq/fe-auth.c b/src/interfaces/libpq/fe-auth.c new file mode 100644 index 0000000..e806264 --- /dev/null +++ b/src/interfaces/libpq/fe-auth.c @@ -0,0 +1,1285 @@ +/*------------------------------------------------------------------------- + * + * fe-auth.c + * The front-end (client) authorization routines + * + * Portions Copyright (c) 1996-2021, 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 <unistd.h> +#include <fcntl.h> +#include <sys/param.h> /* for MAXHOSTNAMELEN on most */ +#include <sys/socket.h> +#ifdef HAVE_SYS_UCRED_H +#include <sys/ucred.h> +#endif +#ifndef MAXHOSTNAMELEN +#include <netdb.h> /* for MAXHOSTNAMELEN on some */ +#endif +#include <pwd.h> +#endif + +#include "common/md5.h" +#include "common/scram-common.h" +#include "fe-auth.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_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) + { + appendPQExpBuffer(&conn->errorMessage, + libpq_gettext("out of memory allocating GSSAPI buffer (%d)\n"), + 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; + } + + maj_stat = gss_init_sec_context(&min_stat, + GSS_C_NO_CREDENTIAL, + &conn->gctx, + conn->gtarg_nam, + GSS_C_NO_OID, + GSS_C_MUTUAL_FLAG, + 0, + GSS_C_NO_CHANNEL_BINDINGS, + (ginbuf.value == NULL) ? GSS_C_NO_BUFFER : &ginbuf, + NULL, + &goutbuf, + NULL, + NULL); + + if (ginbuf.value) + 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. + */ + if (pqPacketSend(conn, 'p', + 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) + gss_release_name(&lmin_s, &conn->gtarg_nam); + + 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')) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("host name must be specified\n")); + return STATUS_ERROR; + } + + if (conn->gctx) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("duplicate GSS authentication request\n")); + 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) + { + appendPQExpBuffer(&conn->errorMessage, + libpq_gettext("out of memory allocating SSPI buffer (%d)\n"), + 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; + } + + 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 */ + if (inputbuf) + 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) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("out of memory\n")); + 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) + { + if (pqPacketSend(conn, 'p', + outbuf.pBuffers[0].pvBuffer, outbuf.pBuffers[0].cbBuffer)) + { + FreeContextBuffer(outbuf.pBuffers[0].pvBuffer); + return STATUS_ERROR; + } + } + FreeContextBuffer(outbuf.pBuffers[0].pvBuffer); + } + + /* 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) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("duplicate SSPI authentication request\n")); + return STATUS_ERROR; + } + + /* + * Retrieve credentials handle + */ + conn->sspicred = malloc(sizeof(CredHandle)); + if (conn->sspicred == NULL) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("out of memory\n")); + 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')) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("host name must be specified\n")); + return STATUS_ERROR; + } + conn->sspitarget = malloc(strlen(conn->krbsrvname) + strlen(host) + 2); + if (!conn->sspitarget) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("out of memory\n")); + 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) +{ + 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) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("channel binding required, but SSL not in use\n")); + goto error; + } + + if (conn->sasl_state) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("duplicate SASL authentication request\n")); + 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 HAVE_PGTLS_GET_PEER_CERTIFICATE_HASH + /* + * 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; +#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 */ + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("channel binding is required, but client does not support it\n")); + 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. + */ + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("server offered SCRAM-SHA-256-PLUS authentication over a non-SSL connection\n")); + goto error; + } + } + else if (strcmp(mechanism_buf.data, SCRAM_SHA_256_NAME) == 0 && + !selected_mechanism) + selected_mechanism = SCRAM_SHA_256_NAME; + } + + if (!selected_mechanism) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("none of the server's SASL authentication mechanisms are supported\n")); + goto error; + } + + if (conn->channel_binding[0] == 'r' && /* require */ + strcmp(selected_mechanism, SCRAM_SHA_256_PLUS_NAME) != 0) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("channel binding is required, but server did not offer an authentication method that supports channel binding\n")); + 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; + } + + /* + * 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, + password, + selected_mechanism); + if (!conn->sasl_state) + goto oom_error; + + /* Get the mechanism-specific Initial Client Response, if any */ + pg_fe_scram_exchange(conn->sasl_state, + NULL, -1, + &initialresponse, &initialresponselen, + &done, &success); + + if (done && !success) + goto error; + + /* + * Build a SASLInitialResponse message, and send it. + */ + if (pqPutMsgStart('p', 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); + if (initialresponse) + free(initialresponse); + + return STATUS_OK; + +error: + termPQExpBuffer(&mechanism_buf); + if (initialresponse) + free(initialresponse); + return STATUS_ERROR; + +oom_error: + termPQExpBuffer(&mechanism_buf); + if (initialresponse) + free(initialresponse); + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("out of memory\n")); + 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) +{ + 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) + { + appendPQExpBuffer(&conn->errorMessage, + libpq_gettext("out of memory allocating SASL buffer (%d)\n"), + 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'; + + pg_fe_scram_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); + + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("AuthenticationSASLFinal received from server, but SASL authentication was not completed\n")); + return STATUS_ERROR; + } + if (outputlen != 0) + { + /* + * 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; +} + +/* + * Respond to AUTH_REQ_SCM_CREDS challenge. + * + * Note: this is dead code as of Postgres 9.1, because current backends will + * never send this challenge. But we must keep it as long as libpq needs to + * interoperate with pre-9.1 servers. It is believed to be needed only on + * Debian/kFreeBSD (ie, FreeBSD kernel with Linux userland, so that the + * getpeereid() function isn't provided by libc). + */ +static int +pg_local_sendauth(PGconn *conn) +{ +#ifdef HAVE_STRUCT_CMSGCRED + char buf; + struct iovec iov; + struct msghdr msg; + struct cmsghdr *cmsg; + union + { + struct cmsghdr hdr; + unsigned char buf[CMSG_SPACE(sizeof(struct cmsgcred))]; + } cmsgbuf; + + /* + * The backend doesn't care what we send here, but it wants exactly one + * character to force recvmsg() to block and wait for us. + */ + buf = '\0'; + iov.iov_base = &buf; + iov.iov_len = 1; + + memset(&msg, 0, sizeof(msg)); + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + + /* We must set up a message that will be filled in by kernel */ + memset(&cmsgbuf, 0, sizeof(cmsgbuf)); + msg.msg_control = &cmsgbuf.buf; + msg.msg_controllen = sizeof(cmsgbuf.buf); + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_len = CMSG_LEN(sizeof(struct cmsgcred)); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_CREDS; + + if (sendmsg(conn->sock, &msg, 0) == -1) + { + char sebuf[PG_STRERROR_R_BUFLEN]; + + appendPQExpBuffer(&conn->errorMessage, + "pg_local_sendauth: sendmsg: %s\n", + strerror_r(errno, sebuf, sizeof(sebuf))); + return STATUS_ERROR; + } + return STATUS_OK; +#else + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("SCM_CRED authentication method not supported\n")); + return STATUS_ERROR; +#endif +} + +static int +pg_password_sendauth(PGconn *conn, const char *password, AuthRequest areq) +{ + 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; + + /* Allocate enough space for two MD5 hashes */ + crypt_pwd = malloc(2 * (MD5_PASSWD_LEN + 1)); + if (!crypt_pwd) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("out of memory\n")); + return STATUS_ERROR; + } + + crypt_pwd2 = crypt_pwd + MD5_PASSWD_LEN + 1; + if (!pg_md5_encrypt(password, conn->pguser, + strlen(conn->pguser), crypt_pwd2)) + { + free(crypt_pwd); + return STATUS_ERROR; + } + if (!pg_md5_encrypt(crypt_pwd2 + strlen("md5"), md5Salt, + 4, crypt_pwd)) + { + 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); + if (crypt_pwd) + free(crypt_pwd); + return ret; +} + +/* + * 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; + + /* + * 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 (!pg_fe_scram_channel_bound(conn->sasl_state)) + { + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("channel binding required, but server authenticated client without channel binding\n")); + result = false; + } + break; + default: + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("channel binding required but not supported by server's authentication request\n")); + 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. + */ +int +pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn) +{ + int oldmsglen; + + if (!check_expected_areq(areq, conn)) + return STATUS_ERROR; + + switch (areq) + { + case AUTH_REQ_OK: + break; + + case AUTH_REQ_KRB4: + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("Kerberos 4 authentication not supported\n")); + return STATUS_ERROR; + + case AUTH_REQ_KRB5: + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("Kerberos 5 authentication not supported\n")); + 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: + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("GSSAPI authentication not supported\n")); + 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: + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("SSPI authentication not supported\n")); + return STATUS_ERROR; +#endif /* !define(ENABLE_GSS) */ +#endif /* ENABLE_SSPI */ + + + case AUTH_REQ_CRYPT: + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("Crypt authentication not supported\n")); + 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; + } + 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; + + case AUTH_REQ_SCM_CREDS: + if (pg_local_sendauth(conn) != STATUS_OK) + return STATUS_ERROR; + break; + + default: + appendPQExpBuffer(&conn->errorMessage, + libpq_gettext("authentication method %u not supported\n"), areq); + return STATUS_ERROR; + } + + return STATUS_OK; +} + + +/* + * 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) +{ + 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 + uid_t user_id = geteuid(); + char pwdbuf[BUFSIZ]; + struct passwd pwdstr; + struct passwd *pw = NULL; + int pwerr; +#endif + + /* + * Some users are using configure --enable-thread-safety-force, so we + * might as well do the locking within our library to protect + * pqGetpwuid(). In fact, application developers can use getpwuid() in + * their application if they use the locking call we provide, or install + * their own locking function using PQregisterThreadLock(). + */ + pglock_thread(); + +#ifdef WIN32 + if (GetUserName(username, &namesize)) + name = username; + else if (errorMessage) + appendPQExpBuffer(errorMessage, + libpq_gettext("user name lookup failure: error code %lu\n"), + GetLastError()); +#else + pwerr = pqGetpwuid(user_id, &pwdstr, pwdbuf, sizeof(pwdbuf), &pw); + if (pw != NULL) + name = pw->pw_name; + else if (errorMessage) + { + if (pwerr != 0) + appendPQExpBuffer(errorMessage, + libpq_gettext("could not look up local user ID %d: %s\n"), + (int) user_id, + strerror_r(pwerr, pwdbuf, sizeof(pwdbuf))); + else + appendPQExpBuffer(errorMessage, + libpq_gettext("local user with ID %d does not exist\n"), + (int) user_id); + } +#endif + + if (name) + { + result = strdup(name); + if (result == NULL && errorMessage) + appendPQExpBufferStr(errorMessage, + libpq_gettext("out of memory\n")); + } + + pgunlock_thread(); + + return result; +} + + +/* + * 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; + + crypt_pwd = malloc(MD5_PASSWD_LEN + 1); + if (!crypt_pwd) + return NULL; + + if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd)) + { + 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; + + resetPQExpBuffer(&conn->errorMessage); + + /* 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); + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("unexpected shape of result set returned for SHOW\n")); + return NULL; + } + val = PQgetvalue(res, 0, 0); + + if (strlen(val) > MAX_ALGORITHM_NAME_LEN) + { + PQclear(res); + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("password_encryption value too long\n")); + 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) + { + crypt_pwd = pg_fe_scram_build_secret(passwd); + } + else if (strcmp(algorithm, "md5") == 0) + { + crypt_pwd = malloc(MD5_PASSWD_LEN + 1); + if (crypt_pwd) + { + if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd)) + { + free(crypt_pwd); + crypt_pwd = NULL; + } + } + } + else + { + appendPQExpBuffer(&conn->errorMessage, + libpq_gettext("unrecognized password encryption algorithm \"%s\"\n"), + algorithm); + return NULL; + } + + if (!crypt_pwd) + appendPQExpBufferStr(&conn->errorMessage, + libpq_gettext("out of memory\n")); + + return crypt_pwd; +} |