(un)signed javascripts modifying forms

[Guest]

I asked a couple of days ago about the following arrangement
(simplified). I made some progress using
netscape.security.PrivilegeManager.enablePrivilege but still have to ask
some further help.

1) a frameset contains
- a number of javascript functions in the head (they do something
like top.frames["UP"].document.myform.elements.value = v
- two frames UP and DOWN

2) the frame UP contains a form, whose action invokes a java servlet
(on the same machine, but by definition port 8080)

3) the servlet writes into frame DOWN (initially blank) a number
of javascript statements, which invoke functions of the form
parent.functioname(argument) ... i.e. those defined in the head
of the frameset

4) the effect of this should be to update some text input areas
or check buttons in the form in frame UP

For demo purposes I could replace step 3 loading in frame DOWN a fixed
set of javascript statements. I could put the source of frame DOWN on
the same server as frame UP, or on a different server.

In the case of the java servlet, as well if the source of DOWN is on a
different server, the javascripts cannot update the form, because of a
breach of the "Mozilla security model" as pointed out by Martin Honnen
(http://www.mozilla.org/projects/security/components/same-origin.html).

The javascripts cannot update the form under Mozilla and Netscape 6/7
(and also 4). They work under Netscape 3 or Konqueror.

I found that I can allow the javascripts residing on a "different
machine" to update the form with the following procedure (which I
derived from the help on signed scripts at
http://developer.netscape.com/viewsource/goodman_sscripts.html), without
bothering with real signed scripts (too much of a hassle for just a few
users !)

1) the user (I will have only 2-3 users) put in their netscape
prefs.js a line like

user_pref("signed.applets.codebase_principal_support", true);

2) I put in my javascript code (WHERE ?) the statements

netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserRead")
netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserWrite")

3) the user sees a popup which asks him to grant or deny privileges
for the unsigned script

Now my question is : what is the appropriate place for the
enablePrivilege statements ? And which of them go where ?

I tried a maximal solution, i.e. enabling both Read and Write in THREE
places :

- the head of the frameset
- the head of the source of frame UP
- the javascript code in frame DOWN

this way it works, but the user is asked 6 times to grant privileges.

I tried putting them only in the head, and it does not work. I get a
"permission denied get property Window.ffff" where ffff is one of the
javascript functions in the head of the frameset

Which privilege should I enable and where to get asked the minimum
possible times ?

 

[Martin Honnen]

LC's No-Spam Newsreading account wrote:

I made some progress using
netscape.security.PrivilegeManager.enablePrivilege but still have to ask
some further help.

2) I put in my javascript code (WHERE ?) the statements

Read

http://www.mozilla.org/projects/security/components/signed-scripts.html#privs

which clearly states

Privileges are granted only in the scope of the requesting function.
This scope includes any functions called by the requesting function.
When the script leaves the requesting function, privileges no longer apply.


Thus you should write a function for the task you have to perform and
inside the function you need to call enable privilege before you try to
access a page loaded from a different origin.


And
http://www.mozilla.org/projects/security/components/jssec.html#privs-list
should tell which privileges you need depending on the task you have to
perform.

 

[Guest]

Read
http://www.mozilla.org/projects/security/components/signed-scripts.html#privs
which clearly states

Privileges are granted only in the scope of the requesting function.

I read that but it didn't seem too clear to me. I also read
http://developer.netscape.com/viewsource/goodman_sscripts.html which
seemed to suggest setting the privileges at page load time.

Presently I enable "UniversalBrowserRead UniversalBrowserWrite" in one
single statement, and I do it 3 times (frameset head, frame with form to
be modified, frame with modifying javascript). This way it works, but
the penalty is that the user has to grant privileges in 3 popups.

I also have to bracket the statement with checks on browser name and
version because not all support rivilegeManager.enablePrivilege with the
same syntax.

Ideally I'd like to reduce the number of OK to grant privileges, but if
no better idea come out, I'll live with 3.