Make contrib/unaccent's unaccent() function work when not in search path.

tglsfdc · tglsfdc · commit d4ab3962613f · 2018-09-06T10:49:45.000-04:00
Since the fixes for CVE-2018-1058, we've advised people to schema-qualify function references in order to fix failures in code that executes under a minimal search_path setting. However, that's insufficient to make the single-argument form of unaccent() work, because it looks up the "unaccent" text search dictionary using the search path. The most expedient answer seems to be to remove the search_path dependency by making it look in the same schema that the unaccent() function itself is declared in. This will definitely work for the normal usage of this function with the unaccent dictionary provided by the extension. It's barely possible that there are people who were relying on the search-path-dependent behavior to select other dictionaries with the same name; but if there are any such people at all, they can still get that behavior by writing unaccent('unaccent', ...), or possibly unaccent('unaccent'::text::regdictionary, ...) if the lookup has to be postponed to runtime. Per complaint from Gunnlaugur Thor Briem. Back-patch to all supported branches. Discussion: https://postgr.es/m/CAPs+M8LCex6d=DeneofdsoJVijaG59m9V0ggbb3pOH7hZO4+cQ@mail.gmail.com
diff --git a/contrib/unaccent/unaccent.c b/contrib/unaccent/unaccent.c
@@ -20,6 +20,8 @@
 #include "tsearch/ts_locale.h"
 #include "tsearch/ts_public.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/syscache.h"
 
 PG_MODULE_MAGIC;
 
@@ -325,7 +327,21 @@ unaccent_dict(PG_FUNCTION_ARGS)
 
 	if (PG_NARGS() == 1)
 	{
-		dictOid = get_ts_dict_oid(stringToQualifiedNameList("unaccent"), false);
+		/*
+		 * Use the "unaccent" dictionary that is in the same schema that this
+		 * function is in.
+		 */
+		Oid			procnspid = get_func_namespace(fcinfo->flinfo->fn_oid);
+		const char *dictname = "unaccent";
+
+		dictOid = GetSysCacheOid2(TSDICTNAMENSP,
+								  PointerGetDatum(dictname),
+								  ObjectIdGetDatum(procnspid));
+		if (!OidIsValid(dictOid))
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("text search dictionary \"%s.%s\" does not exist",
+							get_namespace_name(procnspid), dictname)));
 		strArg = 0;
 	}
 	else
diff --git a/doc/src/sgml/unaccent.sgml b/doc/src/sgml/unaccent.sgml
@@ -142,9 +142,16 @@ mydb=# select ts_headline('fr','H&ocirc;tel de la Mer',to_tsquery('fr','Hotels')
  </indexterm>
 
 <synopsis>
-unaccent(<optional><replaceable class="PARAMETER">dictionary</replaceable>, </optional> <replaceable class="PARAMETER">string</replaceable>) returns <type>text</type>
+unaccent(<optional><replaceable class="parameter">dictionary</replaceable> <type>regdictionary</type>, </optional> <replaceable class="parameter">string</replaceable> <type>text</type>) returns <type>text</type>
 </synopsis>
 
+ <para>
+  If the <replaceable class="parameter">dictionary</replaceable> argument is
+  omitted, the text search dictionary named <literal>unaccent</literal> and
+  appearing in the same schema as the <function>unaccent()</function>
+  function itself is used.
+ </para>
+
  <para>
   For example:
 <programlisting>
