github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/fs/sys/devices.go (about)

     1  // Copyright 2018 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 sys
    16  
    17  import (
    18  	"fmt"
    19  
    20  	"github.com/SagerNet/gvisor/pkg/abi/linux"
    21  	"github.com/SagerNet/gvisor/pkg/context"
    22  	"github.com/SagerNet/gvisor/pkg/sentry/fs"
    23  	"github.com/SagerNet/gvisor/pkg/sentry/fs/fsutil"
    24  	"github.com/SagerNet/gvisor/pkg/sentry/kernel"
    25  )
    26  
    27  // +stateify savable
    28  type cpunum struct {
    29  	fsutil.InodeGenericChecker       `state:"nosave"`
    30  	fsutil.InodeNoExtendedAttributes `state:"nosave"`
    31  	fsutil.InodeNoopRelease          `state:"nosave"`
    32  	fsutil.InodeNoopWriteOut         `state:"nosave"`
    33  	fsutil.InodeNotAllocatable       `state:"nosave"`
    34  	fsutil.InodeNotDirectory         `state:"nosave"`
    35  	fsutil.InodeNotMappable          `state:"nosave"`
    36  	fsutil.InodeNotSocket            `state:"nosave"`
    37  	fsutil.InodeNotSymlink           `state:"nosave"`
    38  	fsutil.InodeNotTruncatable       `state:"nosave"`
    39  	fsutil.InodeNotVirtual           `state:"nosave"`
    40  
    41  	fsutil.InodeSimpleAttributes
    42  	fsutil.InodeStaticFileGetter
    43  }
    44  
    45  var _ fs.InodeOperations = (*cpunum)(nil)
    46  
    47  func newPossible(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
    48  	var maxCore uint
    49  	k := kernel.KernelFromContext(ctx)
    50  	if k != nil {
    51  		maxCore = k.ApplicationCores() - 1
    52  	}
    53  	contents := []byte(fmt.Sprintf("0-%d\n", maxCore))
    54  
    55  	c := &cpunum{
    56  		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, fs.RootOwner, fs.FilePermsFromMode(0444), linux.SYSFS_MAGIC),
    57  		InodeStaticFileGetter: fsutil.InodeStaticFileGetter{
    58  			Contents: contents,
    59  		},
    60  	}
    61  	return newFile(ctx, c, msrc)
    62  }
    63  
    64  func newCPU(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
    65  	m := map[string]*fs.Inode{
    66  		"online":   newPossible(ctx, msrc),
    67  		"possible": newPossible(ctx, msrc),
    68  		"present":  newPossible(ctx, msrc),
    69  	}
    70  
    71  	// Add directories for each of the cpus.
    72  	if k := kernel.KernelFromContext(ctx); k != nil {
    73  		for i := 0; uint(i) < k.ApplicationCores(); i++ {
    74  			m[fmt.Sprintf("cpu%d", i)] = newDir(ctx, msrc, nil)
    75  		}
    76  	}
    77  
    78  	return newDir(ctx, msrc, m)
    79  }
    80  
    81  func newSystemDir(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
    82  	return newDir(ctx, msrc, map[string]*fs.Inode{
    83  		"cpu": newCPU(ctx, msrc),
    84  	})
    85  }
    86  
    87  func newDevicesDir(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
    88  	return newDir(ctx, msrc, map[string]*fs.Inode{
    89  		"system": newSystemDir(ctx, msrc),
    90  	})
    91  }