Bug #53371: COM_FIELD_LIST can be abused to bypass table level grants.

This is the 5.1 merge and extension of the fix.
The server was happily accepting paths in table name in all places a table
name is accepted (e.g. a SELECT). This allowed all users that have some 
privilege over some database to read all tables in all databases in all
mysql server instances that the server file system has access to.
Fixed by :
1. making sure no path elements are allowed in quoted table name when
constructing the path (note that the path symbols are still valid in table names
when they're properly escaped by the server).
2. checking the #mysql50# prefixed names the same way they're checked for
path elements in mysql-5.0.

1 files changed, 26 insertions, 3 deletions

diff --git a/sql/table.cc b/sql/table.cc
index a4e2c59fb87..04d7b3a8d0a 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -494,6 +494,26 @@ inline bool is_system_table_name(const char *name, uint length)
 }
 
 
+/**
+  Check if a string contains path elements
+*/  
+
+static inline bool has_disabled_path_chars(const char *str)
+{
+  for (; *str; str++)
+    switch (*str)
+    {
+      case FN_EXTCHAR:
+      case '/':
+      case '\\':
+      case '~':
+      case '@':
+        return TRUE;
+    }
+  return FALSE;
+}
+
+
 /*
   Read table definition from a binary / text based .frm file
   
@@ -549,7 +569,8 @@ int open_table_def(THD *thd, TABLE_SHARE *share, uint db_flags)
         This kind of tables must have been opened only by the
         my_open() above.
     */
-    if (strchr(share->table_name.str, '@') ||
+    if (has_disabled_path_chars(share->table_name.str) ||
+        has_disabled_path_chars(share->db.str) ||
         !strncmp(share->db.str, MYSQL50_TABLE_NAME_PREFIX,
                  MYSQL50_TABLE_NAME_PREFIX_LENGTH) ||
         !strncmp(share->table_name.str, MYSQL50_TABLE_NAME_PREFIX,
@@ -2711,7 +2732,6 @@ bool check_db_name(LEX_STRING *org_name)
             (name_length > NAME_CHAR_LEN)); /* purecov: inspected */
 }
 
-
 /*
   Allow anything as a table name, as long as it doesn't contain an
   ' ' at the end
@@ -2719,7 +2739,7 @@ bool check_db_name(LEX_STRING *org_name)
 */
 
 
-bool check_table_name(const char *name, uint length)
+bool check_table_name(const char *name, uint length, bool check_for_path_chars)
 {
   uint name_length= 0;  // name length in symbols
   const char *end= name+length;
@@ -2746,6 +2766,9 @@ bool check_table_name(const char *name, uint length)
         continue;
       }
     }
+    if (check_for_path_chars &&
+        (*name == '/' || *name == '\\' || *name == '~' || *name == FN_EXTCHAR))
+      return 1;
 #endif
     name++;
     name_length++;