* Stephen Frost (sfrost@snowman.net) wrote:

>   I've now tested this patch at home w/ 8.2HEAD and it seems to fix the
>   bug.  I plan on testing it under 8.1.2 at work tommorow with
>   mod_auth_krb5, etc, and expect it'll work there.  Assuming all goes
>   well and unless someone objects I'll forward the patch to -patches.
>   It'd be great to have this fixed as it'll allow us to use Kerberos to
>   authenticate to phppgadmin and other web-based tools which use
>   Postgres.

  While playing with this patch under 8.1.2 at home I discovered a
  mistake in how I manually applied one of the hunks to fe-auth.c.
  Basically, the base code had changed and so the patch needed to be
  modified slightly.  This is because the code no longer either has a
  freeable pointer under 'name' or has 'name' as NULL.

  The attached patch correctly frees the string from pg_krb5_authname
  (where it had been strdup'd) if and only if pg_krb5_authname returned
  a string (as opposed to falling through and having name be set using
  name = pw->name;).  Also added a comment to this effect.

Backpatch to 8.1.X.

Stephen Frost

diff --git a/src/interfaces/libpq/fe-auth.c b/src/interfaces/libpq/fe-auth.c
index 5dfeabe..bfcb3b7 100644 (file)
--- a/src/interfaces/libpq/fe-auth.c
+++ b/src/interfaces/libpq/fe-auth.c
@@ -10,7 +10,7 @@
  * exceed INITIAL_EXPBUFFER_SIZE (currently 256 bytes).
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/interfaces/libpq/fe-auth.c,v 1.113 2006/03/05 15:59:08 momjian Exp $
+ *       $PostgreSQL: pgsql/src/interfaces/libpq/fe-auth.c,v 1.114 2006/03/06 17:59:30 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -101,22 +101,33 @@ pg_an_to_ln(char *aname)
  * Various krb5 state which is not connection specific, and a flag to
  * indicate whether we have initialised it yet.
  */
+/* 
 static int     pg_krb5_initialised;
 static krb5_context pg_krb5_context;
 static krb5_ccache pg_krb5_ccache;
 static krb5_principal pg_krb5_client;
 static char *pg_krb5_name;
+*/
+
+struct krb5_info
+{
+       int             pg_krb5_initialised;
+       krb5_context    pg_krb5_context;
+       krb5_ccache     pg_krb5_ccache;
+       krb5_principal  pg_krb5_client;
+       char            *pg_krb5_name;
+};
 
 
 static int
-pg_krb5_init(char *PQerrormsg)
+pg_krb5_init(char *PQerrormsg, struct krb5_info *info)
 {
        krb5_error_code retval;
 
-       if (pg_krb5_initialised)
+       if (info->pg_krb5_initialised)
                return STATUS_OK;
 
-       retval = krb5_init_context(&pg_krb5_context);
+       retval = krb5_init_context(&(info->pg_krb5_context));
        if (retval)
        {
                snprintf(PQerrormsg, PQERRORMSG_LENGTH,
@@ -125,46 +136,56 @@ pg_krb5_init(char *PQerrormsg)
                return STATUS_ERROR;
        }
 
-       retval = krb5_cc_default(pg_krb5_context, &pg_krb5_ccache);
+       retval = krb5_cc_default(info->pg_krb5_context, &(info->pg_krb5_ccache));
        if (retval)
        {
                snprintf(PQerrormsg, PQERRORMSG_LENGTH,
                                 "pg_krb5_init: krb5_cc_default: %s\n",
                                 error_message(retval));
-               krb5_free_context(pg_krb5_context);
+               krb5_free_context(info->pg_krb5_context);
                return STATUS_ERROR;
        }
 
-       retval = krb5_cc_get_principal(pg_krb5_context, pg_krb5_ccache,
-                                                                  &pg_krb5_client);
+       retval = krb5_cc_get_principal(info->pg_krb5_context, info->pg_krb5_ccache,
+                                                                  &(info->pg_krb5_client));
        if (retval)
        {
                snprintf(PQerrormsg, PQERRORMSG_LENGTH,
                                 "pg_krb5_init: krb5_cc_get_principal: %s\n",
                                 error_message(retval));
-               krb5_cc_close(pg_krb5_context, pg_krb5_ccache);
-               krb5_free_context(pg_krb5_context);
+               krb5_cc_close(info->pg_krb5_context, info->pg_krb5_ccache);
+               krb5_free_context(info->pg_krb5_context);
                return STATUS_ERROR;
        }
 
-       retval = krb5_unparse_name(pg_krb5_context, pg_krb5_client, &pg_krb5_name);
+       retval = krb5_unparse_name(info->pg_krb5_context, info->pg_krb5_client, &(info->pg_krb5_name));
        if (retval)
        {
                snprintf(PQerrormsg, PQERRORMSG_LENGTH,
                                 "pg_krb5_init: krb5_unparse_name: %s\n",
                                 error_message(retval));
-               krb5_free_principal(pg_krb5_context, pg_krb5_client);
-               krb5_cc_close(pg_krb5_context, pg_krb5_ccache);
-               krb5_free_context(pg_krb5_context);
+               krb5_free_principal(info->pg_krb5_context, info->pg_krb5_client);
+               krb5_cc_close(info->pg_krb5_context, info->pg_krb5_ccache);
+               krb5_free_context(info->pg_krb5_context);
                return STATUS_ERROR;
        }
 
-       pg_krb5_name = pg_an_to_ln(pg_krb5_name);
+       info->pg_krb5_name = pg_an_to_ln(info->pg_krb5_name);
 
-       pg_krb5_initialised = 1;
+       info->pg_krb5_initialised = 1;
        return STATUS_OK;
 }
 
+static void 
+pg_krb5_destroy(struct krb5_info *info)
+{
+       krb5_free_principal(info->pg_krb5_context, info->pg_krb5_client);
+       krb5_cc_close(info->pg_krb5_context, info->pg_krb5_ccache);
+       krb5_free_context(info->pg_krb5_context);
+       free(info->pg_krb5_name);
+}
+
+
 
 /*
  * pg_krb5_authname -- returns a pointer to static space containing whatever
@@ -173,10 +194,16 @@ pg_krb5_init(char *PQerrormsg)
 static const char *
 pg_krb5_authname(char *PQerrormsg)
 {
-       if (pg_krb5_init(PQerrormsg) != STATUS_OK)
+       char *tmp_name;
+       struct krb5_info info;
+       info.pg_krb5_initialised = 0;
+
+       if (pg_krb5_init(PQerrormsg, &info) != STATUS_OK)
                return NULL;
+       tmp_name = strdup(info.pg_krb5_name);
+       pg_krb5_destroy(&info);
 
-       return pg_krb5_name;
+       return tmp_name;
 }
 
 
@@ -192,6 +219,8 @@ pg_krb5_sendauth(char *PQerrormsg, int sock, const char *hostname, const char *s
        krb5_principal server;
        krb5_auth_context auth_context = NULL;
        krb5_error *err_ret = NULL;
+       struct krb5_info info;
+       info.pg_krb5_initialised = 0;
 
        if (!hostname)
        {
@@ -200,17 +229,18 @@ pg_krb5_sendauth(char *PQerrormsg, int sock, const char *hostname, const char *s
                return STATUS_ERROR;
        }
 
-       ret = pg_krb5_init(PQerrormsg);
+       ret = pg_krb5_init(PQerrormsg, &info);
        if (ret != STATUS_OK)
                return ret;
 
-       retval = krb5_sname_to_principal(pg_krb5_context, hostname, servicename,
+       retval = krb5_sname_to_principal(info.pg_krb5_context, hostname, servicename,
                                                                         KRB5_NT_SRV_HST, &server);
        if (retval)
        {
                snprintf(PQerrormsg, PQERRORMSG_LENGTH,
                                 "pg_krb5_sendauth: krb5_sname_to_principal: %s\n",
                                 error_message(retval));
+               pg_krb5_destroy(&info);
                return STATUS_ERROR;
        }
 
@@ -225,16 +255,17 @@ pg_krb5_sendauth(char *PQerrormsg, int sock, const char *hostname, const char *s
 
                snprintf(PQerrormsg, PQERRORMSG_LENGTH,
                                 libpq_gettext("could not set socket to blocking mode: %s\n"), pqStrerror(errno, sebuf, sizeof(sebuf)));
-               krb5_free_principal(pg_krb5_context, server);
+               krb5_free_principal(info.pg_krb5_context, server);
+               pg_krb5_destroy(&info);
                return STATUS_ERROR;
        }
 
-       retval = krb5_sendauth(pg_krb5_context, &auth_context,
+       retval = krb5_sendauth(info.pg_krb5_context, &auth_context,
                                                   (krb5_pointer) & sock, (char *) servicename,
-                                                  pg_krb5_client, server,
+                                                  info.pg_krb5_client, server,
                                                   AP_OPTS_MUTUAL_REQUIRED,
                                                   NULL, 0,             /* no creds, use ccache instead */
-                                                  pg_krb5_ccache, &err_ret, NULL, NULL);
+                                                  info.pg_krb5_ccache, &err_ret, NULL, NULL);
        if (retval)
        {
                if (retval == KRB5_SENDAUTH_REJECTED && err_ret)
@@ -259,12 +290,12 @@ pg_krb5_sendauth(char *PQerrormsg, int sock, const char *hostname, const char *s
                }
 
                if (err_ret)
-                       krb5_free_error(pg_krb5_context, err_ret);
+                       krb5_free_error(info.pg_krb5_context, err_ret);
 
                ret = STATUS_ERROR;
        }
 
-       krb5_free_principal(pg_krb5_context, server);
+       krb5_free_principal(info.pg_krb5_context, server);
 
        if (!pg_set_noblock(sock))
        {
@@ -275,6 +306,7 @@ pg_krb5_sendauth(char *PQerrormsg, int sock, const char *hostname, const char *s
                                 pqStrerror(errno, sebuf, sizeof(sebuf)));
                ret = STATUS_ERROR;
        }
+       pg_krb5_destroy(&info);
 
        return ret;
 }
@@ -487,6 +519,9 @@ pg_fe_sendauth(AuthRequest areq, PGconn *conn, const char *hostname,
 char *
 pg_fe_getauthname(char *PQerrormsg)
 {
+#ifdef KRB5
+       const char *krb5_name = NULL;
+#endif
        const char *name = NULL;
        char       *authn;
 
@@ -511,7 +546,12 @@ pg_fe_getauthname(char *PQerrormsg)
        pglock_thread();
 
 #ifdef KRB5
-       name = pg_krb5_authname(PQerrormsg);
+       /* pg_krb5_authname gives us a strdup'd value that we need
+        * to free later, however, we don't want to free 'name' directly
+        * in case it's *not* a Kerberos login and we fall through to
+        * name = pw->pw_name; */
+       krb5_name = pg_krb5_authname(PQerrormsg);
+       name = krb5_name;
 #endif
 
        if (!name)
@@ -527,6 +567,12 @@ pg_fe_getauthname(char *PQerrormsg)
 
        authn = name ? strdup(name) : NULL;
 
+#ifdef KRB5
+       /* Free the strdup'd string from pg_krb5_authname, if we got one */
+       if (krb5_name)
+               free(krb5_name);
+#endif
+
        pgunlock_thread();
 
        return authn;