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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"
"strconv"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"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"
)
const (
// Name is the default filesystem name.
Name = "proc"
defaultMaxCachedDentries = uint64(1000)
)
// FilesystemType is the factory class for procfs.
//
// +stateify savable
type FilesystemType struct{}
// Name implements vfs.FilesystemType.Name.
func (FilesystemType) Name() string {
return Name
}
// Release implements vfs.FilesystemType.Release.
func (FilesystemType) Release(ctx context.Context) {}
// +stateify savable
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
}
mopts := vfs.GenericParseMountOptions(opts.Data)
maxCachedDentries := defaultMaxCachedDentries
if str, ok := mopts["dentry_cache_limit"]; ok {
delete(mopts, "dentry_cache_limit")
maxCachedDentries, err = strconv.ParseUint(str, 10, 64)
if err != nil {
ctx.Warningf("proc.FilesystemType.GetFilesystem: invalid dentry cache limit: dentry_cache_limit=%s", str)
return nil, nil, linuxerr.EINVAL
}
}
procfs := &filesystem{
devMinor: devMinor,
}
procfs.MaxCachedDentries = maxCachedDentries
procfs.VFSFilesystem().Init(vfsObj, &ft, procfs)
var fakeCgroupControllers map[string]string
if opts.InternalData != nil {
data := opts.InternalData.(*InternalData)
fakeCgroupControllers = data.Cgroups
}
inode := procfs.newTasksInode(ctx, k, pidns, fakeCgroupControllers)
var dentry kernfs.Dentry
dentry.InitRoot(&procfs.Filesystem, inode)
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)
}
// MountOptions implements vfs.FilesystemImpl.MountOptions.
func (fs *filesystem) MountOptions() string {
return fmt.Sprintf("dentry_cache_limit=%d", fs.MaxCachedDentries)
}
// dynamicInode is an overfitted interface for common Inodes with
// dynamicByteSource types used in procfs.
//
// +stateify savable
type dynamicInode interface {
kernfs.Inode
vfs.DynamicBytesSource
Init(ctx context.Context, creds *auth.Credentials, devMajor, devMinor uint32, ino uint64, data vfs.DynamicBytesSource, perm linux.FileMode)
}
func (fs *filesystem) newInode(ctx context.Context, creds *auth.Credentials, perm linux.FileMode, inode dynamicInode) dynamicInode {
inode.Init(ctx, creds, linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), inode, perm)
return inode
}
// +stateify savable
type staticFile struct {
kernfs.DynamicBytesFile
vfs.StaticData
}
var _ dynamicInode = (*staticFile)(nil)
func newStaticFile(data string) *staticFile {
return &staticFile{StaticData: vfs.StaticData{Data: data}}
}
func (fs *filesystem) newStaticDir(ctx context.Context, creds *auth.Credentials, children map[string]kernfs.Inode) kernfs.Inode {
return kernfs.NewStaticDir(ctx, creds, linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), 0555, children, kernfs.GenericDirectoryFDOptions{
SeekEnd: kernfs.SeekEndZero,
})
}
// InternalData contains internal data passed in to the procfs mount via
// vfs.GetFilesystemOptions.InternalData.
//
// +stateify savable
type InternalData struct {
Cgroups map[string]string
}
// +stateify savable
type implStatFS struct{}
// StatFS implements kernfs.Inode.StatFS.
func (*implStatFS) StatFS(context.Context, *vfs.Filesystem) (linux.Statfs, error) {
return vfs.GenericStatFS(linux.PROC_SUPER_MAGIC), nil
}
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