fe-gssapi-common.c

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/*-------------------------------------------------------------------------
 *
 * fe-gssapi-common.c
 *     The front-end (client) GSSAPI common code
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *      src/interfaces/libpq/fe-gssapi-common.c
 *-------------------------------------------------------------------------
 */
 
#include "postgres_fe.h"
 
#include "fe-gssapi-common.h"
 
#include "libpq-int.h"
#include "pqexpbuffer.h"
 
/*
 * Fetch all errors of a specific type and append to "str".
 * Each error string is preceded by a space.
 */
static void
pg_GSS_error_int(PQExpBuffer str, OM_uint32 stat, int type)
{
    OM_uint32   lmin_s;
    gss_buffer_desc lmsg;
    OM_uint32   msg_ctx = 0;
 
    do
    {
        if (gss_display_status(&lmin_s, stat, type, GSS_C_NO_OID,
                               &msg_ctx, &lmsg) != GSS_S_COMPLETE)
            break;
        appendPQExpBufferChar(str, ' ');
        appendBinaryPQExpBuffer(str, lmsg.value, lmsg.length);
        gss_release_buffer(&lmin_s, &lmsg);
    } while (msg_ctx);
}
 
/*
 * GSSAPI errors contain two parts; put both into conn->errorMessage.
 */
void
pg_GSS_error(const char *mprefix, PGconn *conn,
             OM_uint32 maj_stat, OM_uint32 min_stat)
{
    appendPQExpBuffer(&conn->errorMessage, "%s:", mprefix);
    pg_GSS_error_int(&conn->errorMessage, maj_stat, GSS_C_GSS_CODE);
    appendPQExpBufferChar(&conn->errorMessage, ':');
    pg_GSS_error_int(&conn->errorMessage, min_stat, GSS_C_MECH_CODE);
    appendPQExpBufferChar(&conn->errorMessage, '\n');
}
 
/*
 * Check if we can acquire credentials at all (and yield them if so).
 */
bool
pg_GSS_have_cred_cache(gss_cred_id_t *cred_out)
{
    OM_uint32   major,
                minor;
    gss_cred_id_t cred = GSS_C_NO_CREDENTIAL;
 
    major = gss_acquire_cred(&minor, GSS_C_NO_NAME, 0, GSS_C_NO_OID_SET,
                             GSS_C_INITIATE, &cred, NULL, NULL);
    if (major != GSS_S_COMPLETE)
    {
        *cred_out = NULL;
        return false;
    }
    *cred_out = cred;
    return true;
}
 
/*
 * Try to load service name for a connection
 */
int
pg_GSS_load_servicename(PGconn *conn)
{
    OM_uint32   maj_stat,
                min_stat;
    int         maxlen;
    gss_buffer_desc temp_gbuf;
    char       *host;
 
    if (conn->gtarg_nam != NULL)
        /* Already taken care of - move along */
        return STATUS_OK;
 
    host = PQhost(conn);
    if (!(host && host[0] != '\0'))
    {
        libpq_append_conn_error(conn, "host name must be specified");
        return STATUS_ERROR;
    }
 
    /*
     * Import service principal name so the proper ticket can be acquired by
     * the GSSAPI system.
     */
    maxlen = strlen(conn->krbsrvname) + strlen(host) + 2;
    temp_gbuf.value = (char *) malloc(maxlen);
    if (!temp_gbuf.value)
    {
        libpq_append_conn_error(conn, "out of memory");
        return STATUS_ERROR;
    }
    snprintf(temp_gbuf.value, maxlen, "%s@%s",
             conn->krbsrvname, host);
    temp_gbuf.length = strlen(temp_gbuf.value);
 
    maj_stat = gss_import_name(&min_stat, &temp_gbuf,
                               GSS_C_NT_HOSTBASED_SERVICE, &conn->gtarg_nam);
    free(temp_gbuf.value);
 
    if (maj_stat != GSS_S_COMPLETE)
    {
        pg_GSS_error(libpq_gettext("GSSAPI name import error"),
                     conn,
                     maj_stat, min_stat);
        return STATUS_ERROR;
    }
    return STATUS_OK;
}