Microsoft Sharepoint Products and Technologies Resource Kit eBook

1008 Part IX: Maintaining a Server in Windows SharePoint Services
The SharePoint Products and Technologies class libraries use code access security
to protect certain resources and operations by specifying the permissions that
they require to run. The members of the SharePoint class libraries demand Share-
PointPermission with the ObjectModel property set to true. You should take note of
this and ensure that any assemblies you create that use the WSS object model have
this permission.
Note If you look at the .NET Framework Class Library information, which
can be found on MSDN, you will notice a Requirements section that outlines
the permissions required in order to execute a method.
If the default permission level does not suit your needs, there are several ways
to make sure your code has the required permissions. One option is to consider
installing the assembly in the Global Assembly Cache (GAC) because the code in it,
by default, has Full trust. Installing assemblies in the Global Assembly Cache is not
recommended; it’s best to assign the assembly the lowest level of permissions possible.
Another option is to consider raising the trust level for the virtual server
extended with SharePoint. Yet another option is to create a custom security policy
and assign the needed permissions to the specific assembly or set of assemblies.
Note If you want to know more about raising the trust level for assemblies,
you can refer to “Microsoft Windows SharePoint Services and Code
Access Security” on MSDN.
If your code tries to write data to the WSS database on an HTTP Get, or if the
code needs to enable Web Part to Web Part connections, your code might also need
two other permissions specific to Microsoft SharePoint Products and Technologies:
SharePointPermission.UnsafeSaveOnGet and WebPartPermission.Connections. If
you want to use the classes and the members in the Microsoft.SharePoint.Portal.Single-
SignOn namespace, your code will need an additional permission: SingleSignOn-
Permission.Access. Your code might also need one or more of the default .NET
permissions if it tries to perform an action or access a resource that is protected by
the common language runtime.
Changing trust levels for the virtual server is an easy approach to granting or
revoking permissions. Changing the trust level is a global change affecting all assemblies.
There might be situations in which an administrator might want to either grant
more permissions or reduce the number of permissions granted to specific assemblies.
To do this, you must create a custom code group and add this to the security
policy file.