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efi: introduce internal package and move Absolute detection there
The same code will be shared by the pre-install checks which are going to go into a new package (efi/preinstall), so create an internal package for removing some interdependencies and move the Absolute detection logic there instead
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| // -*- Mode: Go; indent-tabs-mode: t -*- | ||
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| /* | ||
| * Copyright (C) 2024 Canonical Ltd | ||
| * | ||
| * This program is free software: you can redistribute it and/or modify | ||
| * it under the terms of the GNU General Public License version 3 as | ||
| * published by the Free Software Foundation. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License | ||
| * along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
| * | ||
| */ | ||
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| package internal | ||
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| import ( | ||
| "fmt" | ||
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| efi "github.com/canonical/go-efilib" | ||
| "github.com/canonical/go-efilib/guids" | ||
| "github.com/canonical/tcglog-parser" | ||
| ) | ||
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| // IsAbsoluteAgentLaunch returns true if the supplied event corresponds to the launch of an | ||
| // application that is associated with the Absolute (formerly Computrace) endpoint management | ||
| // firmware. This will return false if the event is not associated with an application launch, | ||
| // or the launch is not from a firmware volume, or the launch is from a firmware volume with | ||
| // a filename that is not known to be Absolute. | ||
| // | ||
| // It will return an error if the event data is badly formed, ie, it doesn't decode properly | ||
| // to the EFI_IMAGE_LOAD_EVENT structure, there is an empty device path or a badly formed | ||
| // firmware device path that begins with a firmware volume that is not followed by a single | ||
| // firmware volume filename. | ||
| func IsAbsoluteAgentLaunch(ev *tcglog.Event) (bool, error) { | ||
| if ev.EventType != tcglog.EventTypeEFIBootServicesApplication { | ||
| // Wrong event type | ||
| return false, nil | ||
| } | ||
| data, ok := ev.Data.(*tcglog.EFIImageLoadEvent) | ||
| if !ok { | ||
| // the data resulting from decode errors is guaranteed to implement the error interface | ||
| return false, fmt.Errorf("%s event has wrong data format: %w", tcglog.EventTypeEFIBootServicesApplication, ev.Data.(error)) | ||
| } | ||
| if len(data.DevicePath) == 0 { | ||
| return false, fmt.Errorf("%s event has empty device path", tcglog.EventTypeEFIBootServicesApplication) | ||
| } | ||
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| if _, isFv := data.DevicePath[0].(efi.MediaFvDevicePathNode); !isFv { | ||
| // Not loaded from a flash volume, so this isn't Absolute | ||
| return false, nil | ||
| } | ||
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| // The image is loaded from a flash volume - we should have a path of the form "Fv()\FvFile()". | ||
| if len(data.DevicePath) != 2 { | ||
| return false, fmt.Errorf("invalid firmware volume device path (%v): invalid length (expected 2 components)", data.DevicePath) | ||
| } | ||
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| // The second component should be the filename in the firmware volume (both firmware volumes and the names | ||
| // of files inside those volumes are identified with a GUID, for which there is a public database of well | ||
| // known GUIDs). | ||
| fvf, isFvf := data.DevicePath[1].(efi.MediaFvFileDevicePathNode) | ||
| if !isFvf { | ||
| // The second component is not a firmware volume filename | ||
| return false, fmt.Errorf("invalid firmware volume device path (%v): doesn't terminate with FvFile", data.DevicePath) | ||
| } | ||
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| // We have a complete firmware volume file path. The Absolute installer application has 2 well | ||
| // known names. We can match directly by GUID or do a lookup using data in the public database. | ||
| name, known := guids.FileOrVolumeNameString(efi.GUID(fvf)) | ||
| if !known { | ||
| // This is not a well known GUID and is not Absolute. | ||
| return false, nil | ||
| } | ||
| switch name { | ||
| case "AbsoluteAbtInstaller", "AbsoluteComputraceInstaller": | ||
| return true, nil | ||
| default: | ||
| return false, nil | ||
| } | ||
| } |
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