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// Copyright 2019 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package proc implements a partial in-memory file system for procfs.
package proc
import (
"fmt"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/vfs"
)
// Name is the default filesystem name.
const Name = "proc"
// FilesystemType is the factory class for procfs.
//
// +stateify savable
type FilesystemType struct{}
var _ vfs.FilesystemType = (*FilesystemType)(nil)
// Name implements vfs.FilesystemType.Name.
func (FilesystemType) Name() string {
return Name
}
type filesystem struct {
kernfs.Filesystem
devMinor uint32
}
// GetFilesystem implements vfs.FilesystemType.GetFilesystem.
func (ft FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opts vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) {
k := kernel.KernelFromContext(ctx)
if k == nil {
return nil, nil, fmt.Errorf("procfs requires a kernel")
}
pidns := kernel.PIDNamespaceFromContext(ctx)
if pidns == nil {
return nil, nil, fmt.Errorf("procfs requires a PID namespace")
}
devMinor, err := vfsObj.GetAnonBlockDevMinor()
if err != nil {
return nil, nil, err
}
procfs := &filesystem{
devMinor: devMinor,
}
procfs.VFSFilesystem().Init(vfsObj, &ft, procfs)
var cgroups map[string]string
if opts.InternalData != nil {
data := opts.InternalData.(*InternalData)
cgroups = data.Cgroups
}
_, dentry := procfs.newTasksInode(k, pidns, cgroups)
return procfs.VFSFilesystem(), dentry.VFSDentry(), nil
}
// Release implements vfs.FilesystemImpl.Release.
func (fs *filesystem) Release(ctx context.Context) {
fs.Filesystem.VFSFilesystem().VirtualFilesystem().PutAnonBlockDevMinor(fs.devMinor)
fs.Filesystem.Release(ctx)
}
// dynamicInode is an overfitted interface for common Inodes with
// dynamicByteSource types used in procfs.
type dynamicInode interface {
kernfs.Inode
vfs.DynamicBytesSource
Init(creds *auth.Credentials, devMajor, devMinor uint32, ino uint64, data vfs.DynamicBytesSource, perm linux.FileMode)
}
func (fs *filesystem) newDentry(creds *auth.Credentials, ino uint64, perm linux.FileMode, inode dynamicInode) *kernfs.Dentry {
inode.Init(creds, linux.UNNAMED_MAJOR, fs.devMinor, ino, inode, perm)
d := &kernfs.Dentry{}
d.Init(inode)
return d
}
type staticFile struct {
kernfs.DynamicBytesFile
vfs.StaticData
}
var _ dynamicInode = (*staticFile)(nil)
func newStaticFile(data string) *staticFile {
return &staticFile{StaticData: vfs.StaticData{Data: data}}
}
func newStaticDir(creds *auth.Credentials, devMajor, devMinor uint32, ino uint64, perm linux.FileMode, children map[string]*kernfs.Dentry) *kernfs.Dentry {
return kernfs.NewStaticDir(creds, devMajor, devMinor, ino, perm, children, kernfs.GenericDirectoryFDOptions{
SeekEnd: kernfs.SeekEndZero,
})
}
// InternalData contains internal data passed in to the procfs mount via
// vfs.GetFilesystemOptions.InternalData.
type InternalData struct {
Cgroups map[string]string
}
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