Move to opening an fd on directory opens. Get more careful about symlink races.

diff --git a/source3/smbd/open.c b/source3/smbd/open.c
index 2379b8ebb2efb243978d82b1bd9f8e16a566aa50..89d137506b9e9822c8b21ea54313c628102a55bc 100644 (file)
--- a/source3/smbd/open.c
+++ b/source3/smbd/open.c
@@ -2524,6 +2524,22 @@ static NTSTATUS mkdir_internal(connection_struct *conn,
        return NT_STATUS_OK;
 }
 
+/****************************************************************************
+ Ensure we didn't get symlink raced on opening a directory.
+****************************************************************************/
+
+static bool check_same_stat(const SMB_STRUCT_STAT *sbuf1,
+                       const SMB_STRUCT_STAT *sbuf2)
+{
+       if (sbuf1->st_ex_uid != sbuf2->st_ex_uid ||
+                       sbuf1->st_ex_gid != sbuf2->st_ex_gid ||
+                       sbuf1->st_ex_dev != sbuf2->st_ex_dev ||
+                       sbuf1->st_ex_ino != sbuf2->st_ex_ino) {
+               return false;
+       }
+       return true;
+}
+
 /****************************************************************************
  Open a directory from an NT SMB call.
 ****************************************************************************/
@@ -2726,6 +2742,10 @@ static NTSTATUS open_directory(connection_struct *conn,
 
 #ifdef O_DIRECTORY
        status = fd_open(conn, fsp, O_RDONLY|O_DIRECTORY, 0);
+#else
+       /* POSIX allows us to open a directory with O_RDONLY. */
+       status = fd_open(conn, fsp, O_RDONLY, 0);
+#endif
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(5, ("open_directory: Could not open fd for "
                        "%s (%s)\n",
@@ -2734,7 +2754,23 @@ static NTSTATUS open_directory(connection_struct *conn,
                file_free(req, fsp);
                return status;
        }
-#endif
+
+       status = vfs_stat_fsp(fsp);
+       if (NT_STATUS_IS_OK(status)) {
+               fd_close(fsp);
+               file_free(req, fsp);
+               return status;
+       }
+
+       /* Ensure there was no race condition. */
+       if (!check_same_stat(&smb_dname->st, &fsp->fsp_name->st)) {
+               DEBUG(5,("open_directory: stat struct differs for "
+                       "directory %s.\n",
+                       smb_fname_str_dbg(smb_dname)));
+               fd_close(fsp);
+               file_free(req, fsp);
+               return NT_STATUS_ACCESS_DENIED;
+       }
 
        lck = get_share_mode_lock(talloc_tos(), fsp->file_id,
                                  conn->connectpath, smb_dname, &mtimespec);