Hi,
On Tue, Dec 31, 2024 at 02:52:53PM +0100, Samuel Thibault wrote:
>
> You should probably check precisely the difference between Linux and
> Hurd on these alignment questions at the various stages.
>
I placed a `g_message` call in `g_unix_credentials_message_deserialize` and
on Linux it doesn't get triggered, it instead goes through
`g_socket_get_credentials`:
# GLib-GIO-DEBUG: Accepting "EXTERNAL" authentication
# GLib-GIO-MESSAGE: [g_socket_get_credentials] optlen=12
# GLib-GIO-DEBUG: Authorizing peer with credentials:
GCredentials:linux-ucred:pid=87865,uid=1000,gid=1000
It takes the branch where G_CREDENTIALS_SOCKET_GET_CREDENTIALS_SUPPORTED
and SO_PEERCRED is defined.
This function gets called from gio/gdbusauth.c: _g_dbus_auth_run_server if
G_CREDENTIALS_PREFER_MESSAGE_PASSING is not defined (which is the case on
Linux).
To summarize:
On Linux
========
#define G_CREDENTIALS_UNIX_CREDENTIALS_MESSAGE_SUPPORTED 1
#define G_CREDENTIALS_SOCKET_GET_CREDENTIALS_SUPPORTED 1
#undef G_CREDENTIALS_PREFER_MESSAGE_PASSING
g_socket_get_credentials is called which uses getsockopt and SO_PEERCRED
On Hurd
=======
#define G_CREDENTIALS_UNIX_CREDENTIALS_MESSAGE_SUPPORTED 1
#undef G_CREDENTIALS_SOCKET_GET_CREDENTIALS_SUPPORTED
#define G_CREDENTIALS_PREFER_MESSAGE_PASSING 1
g_unix_connection_receive_credentials is called which in turn calls:
- g_unix_connection_receive_credentials
- g_socket_receive_message
- g_socket_control_message_deserialize
- g_unix_credentials_message_deserialize
So, I went ahead and defined G_CREDENTIALS_PREFER_MESSAGE_PASSING on Linux
and to my surprise it didn't fail :P
Instead the correct size was being computed:
# GLib-GIO-MESSAGE: [input_message_from_msghdr]
level=1,type=2,len=28,extra=16
# GLib-GIO-MESSAGE: [input_message_from_msghdr]
cmsg=0x7ff46d6c5d40,data=0x7ff46d6c5d50
# GLib-GIO-MESSAGE: [g_socket_control_message_deserialize] level=1, type=2,
size=12
# GLib-GIO-MESSAGE: [g_unix_credentials_message_deserialize] size=12,
native=12
It must be something we are doing wrong on our side. I'll apply the logging to
my Hurd
box and see what comes out.
