ahci_drv default writeable?

[Christian Helmuth]

Hello Steve,

On Tue, Sep 26, 2017 at 11:59:17AM -0500, Steven Harp wrote:
> Noticed that in 17.08 (and 17.05) these examples failed w. x86/nova
> - run/libc_vfs_fs_fat
> - run/libc_vfs_fat
> apparently because:
> 
>  [init -> ahci_drv] read-only session opened at device 0 for 'test-libc_vfs -> 0'
> 
> so e.g., mkdir fails with EPERM.
> 
> Hacking libports/run/libc_vfs_filesystem_test.inc to add writeable="yes"
> to the "ahci_drv" component configuration:
>                 <config>
>                         <policy label_prefix="test-libc_vfs" device="0" writeable="yes"/>
>                         <policy label_prefix="vfs" device="0" writeable="yes" />
>                 </config>
> suffices, but maybe this is not appropriate. Was the default policy intended to be
> writeable="yes" for this driver?

The writeable policy attribute was introduced with 17.08 in

  https://github.com/genodelabs/genode/commit/1fce8d0d7

and this commit also adapts the autopilot tests. Unfortunately, we
missed to adapt libc_vfs_fs_fat and libc_vfs_fat, which remained
undetected because those are not in tool/autopilot.list. The reason
behind this is that the run scripts already use depot packages which
our nightly build does not support currently.

Regarding your original question: Yes, with least privilege in mind
the default setting of "writeable" is false, which can be lifted by
specifying writeable="true" in the policy node (as you already did).

Thanks for reporting, I already crafted a patch for
repos/libports/run/libc_vfs_filesystem_test.inc in

  https://github.com/genodelabs/genode/commit/8afb9f8

Regards
-- 
Christian Helmuth
Genode Labs

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