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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2019 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/>.
*
*/
package builtin
import (
"fmt"
"os"
"path/filepath"
"regexp"
"strings"
"github.com/snapcore/snapd/interfaces"
"github.com/snapcore/snapd/interfaces/apparmor"
"github.com/snapcore/snapd/interfaces/udev"
"github.com/snapcore/snapd/logger"
"github.com/snapcore/snapd/snap"
)
// https://www.kernel.org/doc/html/latest/driver-api/uio-howto.html
const uioSummary = `allows access to specific uio device`
const uioBaseDeclarationSlots = `
uio:
allow-installation:
slot-snap-type:
- core
- gadget
deny-auto-connection: true
`
type uioInterface struct{}
func (iface *uioInterface) Name() string {
return "uio"
}
func (iface *uioInterface) StaticInfo() interfaces.StaticInfo {
return interfaces.StaticInfo{
Summary: uioSummary,
BaseDeclarationSlots: uioBaseDeclarationSlots,
}
}
var uioPattern = regexp.MustCompile(`^/dev/uio[0-9]+$`)
const invalidUioDeviceNodeSlotPathErrFmt = "slot %q path attribute must be a valid UIO device node"
func (iface *uioInterface) path(slotRef *interfaces.SlotRef, attrs interfaces.Attrer) (string, error) {
return verifySlotPathAttribute(slotRef, attrs, uioPattern, invalidUioDeviceNodeSlotPathErrFmt)
}
func (iface *uioInterface) BeforePrepareSlot(slot *snap.SlotInfo) error {
_, err := verifySlotPathAttribute(&interfaces.SlotRef{Snap: slot.Snap.InstanceName(), Name: slot.Name}, slot, uioPattern, invalidUioDeviceNodeSlotPathErrFmt)
return err
}
func (iface *uioInterface) AppArmorConnectedPlug(spec *apparmor.Specification, plug *interfaces.ConnectedPlug, slot *interfaces.ConnectedSlot) error {
path, err := iface.path(slot.Ref(), slot)
if err != nil {
return nil
}
spec.AddSnippet(fmt.Sprintf("%s rw,", path))
// Assuming sysfs_base is /sys/class/uio/uio[0-9]+ where the leaf directory
// name matches /dev/uio[0-9]+ device name, the following files exists or
// may exist:
// - $sysfs_base/{name,version,event}
// - $sysfs_base/maps/map[0-9]+/{addr,name,offset,size}
// - $sysfs_base/portio/port[0-9]+/{name,start,size,porttype}
// The expression below matches them all as they all may be required for
// userspace drivers to operate.
//
// While it is more accurate to use:
//
// "/sys/devices/platform/**/uio/%s/** r,", strings.TrimPrefix(path, "/dev/")
//
// multiple interface connections will result in overlapping deep
// globs of the form:
//
// /sys/devices/platform/**/uio/uio1/** r,
// /sys/devices/platform/**/uio/uio2/** r,
// /sys/devices/platform/**/uio/uioN/** r,
//
// which are computationally difficult to de-duplicate provided
// large enough N. Instead, grant read only access to all uio
// sysfs files and control writable access to the specific
// device node in /dev. Use AddDeduplicatedSnippet() for clarity
// in the resulting rules.
spec.AddDeduplicatedSnippet("/sys/devices/platform/**/uio/uio[0-9]** r, # common rule for all uio connections")
// Allow uio configuration
uioConfigPath := filepath.Join("/sys/class/uio/", strings.TrimPrefix(path, "/dev/"), "/device/config")
dereferencedPath, err := evalSymlinks(uioConfigPath)
if err != nil && os.IsNotExist(err) {
// This should not block the interface connection operation
logger.Noticef("cannot configure not existing uio device config file %s", uioConfigPath)
return nil
}
if err != nil {
return err
}
spec.AddSnippet(fmt.Sprintf("%s rwk,", dereferencedPath))
return nil
}
func (iface *uioInterface) UDevConnectedPlug(spec *udev.Specification, plug *interfaces.ConnectedPlug, slot *interfaces.ConnectedSlot) error {
path, err := iface.path(slot.Ref(), slot)
if err != nil {
return nil
}
spec.TagDevice(fmt.Sprintf(`SUBSYSTEM=="uio", KERNEL=="%s"`, strings.TrimPrefix(path, "/dev/")))
return nil
}
func (iface *uioInterface) AutoConnect(*snap.PlugInfo, *snap.SlotInfo) bool {
// Allow what is allowed in the declarations
return true
}
func init() {
registerIface(&uioInterface{})
}
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