github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/fs/proc/version.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 proc
    16  
    17  import (
    18  	"fmt"
    19  
    20  	"github.com/SagerNet/gvisor/pkg/context"
    21  	"github.com/SagerNet/gvisor/pkg/sentry/fs/proc/seqfile"
    22  	"github.com/SagerNet/gvisor/pkg/sentry/kernel"
    23  )
    24  
    25  // LINT.IfChange
    26  
    27  // versionData backs /proc/version.
    28  //
    29  // +stateify savable
    30  type versionData struct {
    31  	// k is the owning Kernel.
    32  	k *kernel.Kernel
    33  }
    34  
    35  // NeedsUpdate implements seqfile.SeqSource.NeedsUpdate.
    36  func (*versionData) NeedsUpdate(generation int64) bool {
    37  	return true
    38  }
    39  
    40  // ReadSeqFileData implements seqfile.SeqSource.ReadSeqFileData.
    41  func (v *versionData) ReadSeqFileData(ctx context.Context, h seqfile.SeqHandle) ([]seqfile.SeqData, int64) {
    42  	if h != nil {
    43  		return nil, 0
    44  	}
    45  
    46  	init := v.k.GlobalInit()
    47  	if init == nil {
    48  		// Attempted to read before the init Task is created. This can
    49  		// only occur during startup, which should never need to read
    50  		// this file.
    51  		panic("Attempted to read version before initial Task is available")
    52  	}
    53  
    54  	// /proc/version takes the form:
    55  	//
    56  	// "SYSNAME version RELEASE (COMPILE_USER@COMPILE_HOST)
    57  	// (COMPILER_VERSION) VERSION"
    58  	//
    59  	// where:
    60  	// - SYSNAME, RELEASE, and VERSION are the same as returned by
    61  	// sys_utsname
    62  	// - COMPILE_USER is the user that build the kernel
    63  	// - COMPILE_HOST is the hostname of the machine on which the kernel
    64  	// was built
    65  	// - COMPILER_VERSION is the version reported by the building compiler
    66  	//
    67  	// Since we don't really want to expose build information to
    68  	// applications, those fields are omitted.
    69  	//
    70  	// FIXME(mpratt): Using Version from the init task SyscallTable
    71  	// disregards the different version a task may have (e.g., in a uts
    72  	// namespace).
    73  	ver := init.Leader().SyscallTable().Version
    74  	return []seqfile.SeqData{
    75  		{
    76  			Buf:    []byte(fmt.Sprintf("%s version %s %s\n", ver.Sysname, ver.Release, ver.Version)),
    77  			Handle: (*versionData)(nil),
    78  		},
    79  	}, 0
    80  }
    81  
    82  // LINT.ThenChange(../../fsimpl/proc/task_files.go)