github.com/MerlinKodo/gvisor@v0.0.0-20231110090155-957f62ecf90e/pkg/sentry/devices/memdev/memdev.go (about)

     1  // Copyright 2020 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package memdev implements "mem" character devices, as implemented in Linux
    16  // by drivers/char/mem.c and drivers/char/random.c.
    17  package memdev
    18  
    19  import (
    20  	"github.com/MerlinKodo/gvisor/pkg/abi/linux"
    21  	"github.com/MerlinKodo/gvisor/pkg/context"
    22  	"github.com/MerlinKodo/gvisor/pkg/sentry/fsimpl/devtmpfs"
    23  	"github.com/MerlinKodo/gvisor/pkg/sentry/vfs"
    24  )
    25  
    26  // Register registers all devices implemented by this package in vfsObj.
    27  func Register(vfsObj *vfs.VirtualFilesystem) error {
    28  	for minor, dev := range map[uint32]vfs.Device{
    29  		nullDevMinor:    nullDevice{},
    30  		zeroDevMinor:    zeroDevice{},
    31  		fullDevMinor:    fullDevice{},
    32  		randomDevMinor:  randomDevice{},
    33  		urandomDevMinor: randomDevice{},
    34  	} {
    35  		if err := vfsObj.RegisterDevice(vfs.CharDevice, linux.MEM_MAJOR, minor, dev, &vfs.RegisterDeviceOptions{
    36  			GroupName: "mem",
    37  		}); err != nil {
    38  			return err
    39  		}
    40  	}
    41  	return nil
    42  }
    43  
    44  // CreateDevtmpfsFiles creates device special files in dev representing all
    45  // devices implemented by this package.
    46  func CreateDevtmpfsFiles(ctx context.Context, dev *devtmpfs.Accessor) error {
    47  	for minor, name := range map[uint32]string{
    48  		nullDevMinor:    "null",
    49  		zeroDevMinor:    "zero",
    50  		fullDevMinor:    "full",
    51  		randomDevMinor:  "random",
    52  		urandomDevMinor: "urandom",
    53  	} {
    54  		if err := dev.CreateDeviceFile(ctx, name, vfs.CharDevice, linux.MEM_MAJOR, minor, 0666 /* mode */); err != nil {
    55  			return err
    56  		}
    57  	}
    58  	return nil
    59  }