Fix for Bug #41597 - After rename of user, there are additional grants when

                     grants are reapplied.


After renaming a user and trying to re-apply grants results in additional
grants.

This is because we use username as part of the key for GRANT_TABLE structure.
When the user is renamed, we only change the username stored and the hash key
still contains the old user name and this results in the extra privileges

Fixed by rebuilding the hash key and updating the column_priv_hash structure
when the user is renamed

mysql-test/r/grant3.result:
  Bug #41597 - After rename of user, there are additional grants when 
               grants are reapplied.
  
  Testcase for BUG#41597
mysql-test/t/grant3.test:
  Bug #41597 - After rename of user, there are additional grants when 
               grants are reapplied.
  
  Testcase for BUG#41597
sql/sql_acl.cc:
  Bug #41597 - After rename of user, there are additional grants when 
               grants are reapplied.
  
  Fixed handle_grant_struct() to update the hash key when the user is renamed.
  Added to set_user_details() method to GRANT_NAME class

mysql-test/r/grant3.result

@@ -154,4 +154,42 @@ SELECT * FROM mysqltest_1.t1;
 a
 DROP USER 'mysqltest1'@'%';
 DROP DATABASE mysqltest_1;
+#
+# Bug#41597 - After rename of user, there are additional grants
+#             when grants are reapplied.
+#
+CREATE DATABASE temp;
+CREATE TABLE temp.t1(a INT, b VARCHAR(10));
+INSERT INTO temp.t1 VALUES(1, 'name1');
+INSERT INTO temp.t1 VALUES(2, 'name2');
+INSERT INTO temp.t1 VALUES(3, 'name3');
+CREATE USER 'user1'@'%';
+RENAME USER 'user1'@'%' TO 'user2'@'%';
+# Show privileges after rename and BEFORE grant
+SHOW GRANTS FOR 'user2'@'%';
+Grants for user2@%
+GRANT USAGE ON *.* TO 'user2'@'%'
+GRANT SELECT (a), INSERT (b) ON `temp`.`t1` TO 'user2'@'%';
+# Show privileges after rename and grant
+SHOW GRANTS FOR 'user2'@'%';
+Grants for user2@%
+GRANT USAGE ON *.* TO 'user2'@'%'
+GRANT SELECT (a), INSERT (b) ON `temp`.`t1` TO 'user2'@'%'
+# Connect as the renamed user
+SHOW GRANTS;
+Grants for user2@%
+GRANT USAGE ON *.* TO 'user2'@'%'
+GRANT SELECT (a), INSERT (b) ON `temp`.`t1` TO 'user2'@'%'
+SELECT a FROM temp.t1;
+a
+1
+2
+3
+# Check for additional privileges by accessing a
+# non privileged column. We shouldn't be able to 
+# access this column.
+SELECT b FROM temp.t1;
+ERROR 42000: SELECT command denied to user 'user2'@'localhost' for column 'b' in table 't1'
+DROP USER 'user2'@'%';
+DROP DATABASE temp;
 End of 5.0 tests

mysql-test/t/grant3.test

@@ -163,6 +163,41 @@ connection default;
 DROP USER 'mysqltest1'@'%';
 DROP DATABASE mysqltest_1;
 
+--echo #
+--echo # Bug#41597 - After rename of user, there are additional grants
+--echo #             when grants are reapplied.
+--echo #
+
+CREATE DATABASE temp;
+CREATE TABLE temp.t1(a INT, b VARCHAR(10));
+INSERT INTO temp.t1 VALUES(1, 'name1');
+INSERT INTO temp.t1 VALUES(2, 'name2');
+INSERT INTO temp.t1 VALUES(3, 'name3');
+
+
+CREATE USER 'user1'@'%';
+RENAME USER 'user1'@'%' TO 'user2'@'%';
+--echo # Show privileges after rename and BEFORE grant
+SHOW GRANTS FOR 'user2'@'%';
+GRANT SELECT (a), INSERT (b) ON `temp`.`t1` TO 'user2'@'%';
+--echo # Show privileges after rename and grant
+SHOW GRANTS FOR 'user2'@'%';
+
+--echo # Connect as the renamed user
+connect (conn1, localhost, user2,,);
+connection conn1;
+SHOW GRANTS;
+SELECT a FROM temp.t1;
+--echo # Check for additional privileges by accessing a
+--echo # non privileged column. We shouldn't be able to 
+--echo # access this column.
+--error ER_COLUMNACCESS_DENIED_ERROR 
+SELECT b FROM temp.t1;
+disconnect conn1;
+
+connection default;
+DROP USER 'user2'@'%';
+DROP DATABASE temp;
 
 --echo End of 5.0 tests
 

sql/sql_acl.cc

@@ -2096,6 +2096,8 @@ public:
   GRANT_NAME (TABLE *form);
   virtual ~GRANT_NAME() {};
   virtual bool ok() { return privs != 0; }
+  void set_user_details(const char *h, const char *d,
+                        const char *u, const char *t);
 };
 
 
@@ -2113,27 +2115,36 @@ public:
 };
 
 
-
-GRANT_NAME::GRANT_NAME(const char *h, const char *d,const char *u,
-                       const char *t, ulong p)
-  :privs(p)
+void GRANT_NAME::set_user_details(const char *h, const char *d,
+                                  const char *u, const char *t)
 {
   /* Host given by user */
   update_hostname(&host, strdup_root(&memex, h));
-  db =   strdup_root(&memex,d);
+  if (db != d)
+  {
+    db= strdup_root(&memex, d);
+    if (lower_case_table_names)
+      my_casedn_str(files_charset_info, db);
+  }
   user = strdup_root(&memex,u);
   sort=  get_sort(3,host.hostname,db,user);
-  tname= strdup_root(&memex,t);
-  if (lower_case_table_names)
+  if (tname != t)
   {
-    my_casedn_str(files_charset_info, db);
-    my_casedn_str(files_charset_info, tname);
+    tname= strdup_root(&memex, t);
+    if (lower_case_table_names)
+      my_casedn_str(files_charset_info, tname);
   }
   key_length =(uint) strlen(d)+(uint) strlen(u)+(uint) strlen(t)+3;
   hash_key = (char*) alloc_root(&memex,key_length);
   strmov(strmov(strmov(hash_key,user)+1,db)+1,tname);
 }
 
+GRANT_NAME::GRANT_NAME(const char *h, const char *d,const char *u,
+                       const char *t, ulong p)
+  :db(0), tname(0), privs(p)
+{
+  set_user_details(h, d, u, t);
+}
 
 GRANT_TABLE::GRANT_TABLE(const char *h, const char *d,const char *u,
                 	 const char *t, ulong p, ulong c)
@@ -5183,9 +5194,20 @@ static int handle_grant_struct(uint struct_no, bool drop,
 
       case 2:
       case 3:
-        grant_name->user= strdup_root(&mem, user_to->user.str);
-        update_hostname(&grant_name->host,
-                        strdup_root(&mem, user_to->host.str));
+        /* 
+          Update the grant structure with the new user name and
+          host name
+        */
+        grant_name->set_user_details(user_to->host.str, grant_name->db,
+                                   user_to->user.str, grant_name->tname);
+
+        /*
+          Since username is part of the hash key, when the user name
+          is renamed, the hash key is changed. Update the hash to
+          ensure that the position matches the new hash key value
+        */
+        hash_update(&column_priv_hash, (byte *)grant_name,
+                    grant_name->hash_key, grant_name->key_length);
 	break;
       }
     }