summaryrefslogtreecommitdiffhomepage
path: root/pkg/sentry/fs/proc/sys.go
blob: aab891c53232ffb737a86d3efd8cf0f0aa5d160f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
// Copyright 2018 Google Inc.
//
// 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

import (
	"fmt"
	"io"

	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/proc/seqfile"
	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
	"gvisor.googlesource.com/gvisor/pkg/sentry/socket/rpcinet"
	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
)

// hostname is a file containing the system hostname.
type hostname struct {
	ramfs.Entry
}

// DeprecatedPreadv implements fs.InodeOperations.DeprecatedPreadv.
func (hostname) DeprecatedPreadv(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
	utsns := kernel.UTSNamespaceFromContext(ctx)
	contents := []byte(utsns.HostName() + "\n")

	if offset >= int64(len(contents)) {
		return 0, io.EOF
	}

	n, err := dst.CopyOut(ctx, contents[offset:])
	return int64(n), err
}

func (p *proc) newHostname(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
	h := &hostname{}
	h.InitEntry(ctx, fs.RootOwner, fs.FilePermsFromMode(0444))
	return newFile(h, msrc, fs.SpecialFile, nil)
}

// mmapMinAddrData backs /proc/sys/vm/mmap_min_addr.
type mmapMinAddrData struct {
	k *kernel.Kernel
}

// NeedsUpdate implements seqfile.SeqSource.NeedsUpdate.
func (*mmapMinAddrData) NeedsUpdate(generation int64) bool {
	return true
}

// ReadSeqFileData implements seqfile.SeqSource.ReadSeqFileData.
func (d *mmapMinAddrData) ReadSeqFileData(ctx context.Context, h seqfile.SeqHandle) ([]seqfile.SeqData, int64) {
	if h != nil {
		return nil, 0
	}
	return []seqfile.SeqData{
		{
			Buf:    []byte(fmt.Sprintf("%d\n", d.k.Platform.MinUserAddress())),
			Handle: (*mmapMinAddrData)(nil),
		},
	}, 0
}

type overcommitMemory struct{}

func (*overcommitMemory) NeedsUpdate(generation int64) bool {
	return true
}

// ReadSeqFileData implements seqfile.SeqSource.
func (*overcommitMemory) ReadSeqFileData(ctx context.Context, h seqfile.SeqHandle) ([]seqfile.SeqData, int64) {
	if h != nil {
		return nil, 0
	}
	return []seqfile.SeqData{
		{
			Buf:    []byte("0\n"),
			Handle: (*overcommitMemory)(nil),
		},
	}, 0
}

func (p *proc) newKernelDir(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
	d := &ramfs.Dir{}
	d.InitDir(ctx, nil, fs.RootOwner, fs.FilePermsFromMode(0555))
	d.AddChild(ctx, "hostname", p.newHostname(ctx, msrc))
	return newFile(d, msrc, fs.SpecialDirectory, nil)
}

func (p *proc) newVMDir(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
	d := &ramfs.Dir{}
	d.InitDir(ctx, nil, fs.RootOwner, fs.FilePermsFromMode(0555))
	d.AddChild(ctx, "mmap_min_addr", seqfile.NewSeqFileInode(ctx, &mmapMinAddrData{p.k}, msrc))
	d.AddChild(ctx, "overcommit_memory", seqfile.NewSeqFileInode(ctx, &overcommitMemory{}, msrc))
	return newFile(d, msrc, fs.SpecialDirectory, nil)
}

func (p *proc) newSysDir(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
	d := &ramfs.Dir{}
	d.InitDir(ctx, nil, fs.RootOwner, fs.FilePermsFromMode(0555))
	d.AddChild(ctx, "kernel", p.newKernelDir(ctx, msrc))
	d.AddChild(ctx, "vm", p.newVMDir(ctx, msrc))

	// If we're using rpcinet we will let it manage /proc/sys/net.
	if _, ok := p.k.NetworkStack().(*rpcinet.Stack); ok {
		d.AddChild(ctx, "net", newRPCInetProcSysNet(ctx, msrc))
	} else {
		d.AddChild(ctx, "net", p.newSysNetDir(ctx, msrc))
	}

	return newFile(d, msrc, fs.SpecialDirectory, nil)
}