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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
import (
"bytes"
"fmt"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
"gvisor.dev/gvisor/pkg/sentry/inet"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/usermem"
)
// newSysDir returns the dentry corresponding to /proc/sys directory.
func newSysDir(root *auth.Credentials, inoGen InoGenerator, k *kernel.Kernel) *kernfs.Dentry {
return kernfs.NewStaticDir(root, inoGen.NextIno(), 0555, map[string]*kernfs.Dentry{
"kernel": kernfs.NewStaticDir(root, inoGen.NextIno(), 0555, map[string]*kernfs.Dentry{
"hostname": newDentry(root, inoGen.NextIno(), 0444, &hostnameData{}),
"shmall": newDentry(root, inoGen.NextIno(), 0444, shmData(linux.SHMALL)),
"shmmax": newDentry(root, inoGen.NextIno(), 0444, shmData(linux.SHMMAX)),
"shmmni": newDentry(root, inoGen.NextIno(), 0444, shmData(linux.SHMMNI)),
}),
"vm": kernfs.NewStaticDir(root, inoGen.NextIno(), 0555, map[string]*kernfs.Dentry{
"mmap_min_addr": newDentry(root, inoGen.NextIno(), 0444, &mmapMinAddrData{}),
"overcommit_memory": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0\n")),
}),
"net": newSysNetDir(root, inoGen, k),
})
}
// newSysNetDir returns the dentry corresponding to /proc/sys/net directory.
func newSysNetDir(root *auth.Credentials, inoGen InoGenerator, k *kernel.Kernel) *kernfs.Dentry {
var contents map[string]*kernfs.Dentry
// TODO(gvisor.dev/issue/1833): Support for using the network stack in the
// network namespace of the calling process.
if stack := k.RootNetworkNamespace().Stack(); stack != nil {
contents = map[string]*kernfs.Dentry{
"ipv4": kernfs.NewStaticDir(root, inoGen.NextIno(), 0555, map[string]*kernfs.Dentry{
"tcp_sack": newDentry(root, inoGen.NextIno(), 0644, &tcpSackData{stack: stack}),
// The following files are simple stubs until they are implemented in
// netstack, most of these files are configuration related. We use the
// value closest to the actual netstack behavior or any empty file, all
// of these files will have mode 0444 (read-only for all users).
"ip_local_port_range": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("16000 65535")),
"ip_local_reserved_ports": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("")),
"ipfrag_time": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("30")),
"ip_nonlocal_bind": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"ip_no_pmtu_disc": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("1")),
// tcp_allowed_congestion_control tell the user what they are able to
// do as an unprivledged process so we leave it empty.
"tcp_allowed_congestion_control": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("")),
"tcp_available_congestion_control": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("reno")),
"tcp_congestion_control": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("reno")),
// Many of the following stub files are features netstack doesn't
// support. The unsupported features return "0" to indicate they are
// disabled.
"tcp_base_mss": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("1280")),
"tcp_dsack": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"tcp_early_retrans": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"tcp_fack": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"tcp_fastopen": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"tcp_fastopen_key": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("")),
"tcp_invalid_ratelimit": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"tcp_keepalive_intvl": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"tcp_keepalive_probes": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"tcp_keepalive_time": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("7200")),
"tcp_mtu_probing": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"tcp_no_metrics_save": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("1")),
"tcp_probe_interval": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"tcp_probe_threshold": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"tcp_retries1": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("3")),
"tcp_retries2": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("15")),
"tcp_rfc1337": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("1")),
"tcp_slow_start_after_idle": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("1")),
"tcp_synack_retries": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("5")),
"tcp_syn_retries": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("3")),
"tcp_timestamps": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("1")),
}),
"core": kernfs.NewStaticDir(root, inoGen.NextIno(), 0555, map[string]*kernfs.Dentry{
"default_qdisc": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("pfifo_fast")),
"message_burst": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("10")),
"message_cost": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("5")),
"optmem_max": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("0")),
"rmem_default": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("212992")),
"rmem_max": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("212992")),
"somaxconn": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("128")),
"wmem_default": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("212992")),
"wmem_max": newDentry(root, inoGen.NextIno(), 0444, newStaticFile("212992")),
}),
}
}
return kernfs.NewStaticDir(root, inoGen.NextIno(), 0555, map[string]*kernfs.Dentry{
"net": kernfs.NewStaticDir(root, inoGen.NextIno(), 0555, contents),
})
}
// mmapMinAddrData implements vfs.DynamicBytesSource for
// /proc/sys/vm/mmap_min_addr.
//
// +stateify savable
type mmapMinAddrData struct {
kernfs.DynamicBytesFile
k *kernel.Kernel
}
var _ dynamicInode = (*mmapMinAddrData)(nil)
// Generate implements vfs.DynamicBytesSource.Generate.
func (d *mmapMinAddrData) Generate(ctx context.Context, buf *bytes.Buffer) error {
fmt.Fprintf(buf, "%d\n", d.k.Platform.MinUserAddress())
return nil
}
// hostnameData implements vfs.DynamicBytesSource for /proc/sys/kernel/hostname.
//
// +stateify savable
type hostnameData struct {
kernfs.DynamicBytesFile
}
var _ dynamicInode = (*hostnameData)(nil)
// Generate implements vfs.DynamicBytesSource.Generate.
func (*hostnameData) Generate(ctx context.Context, buf *bytes.Buffer) error {
utsns := kernel.UTSNamespaceFromContext(ctx)
buf.WriteString(utsns.HostName())
buf.WriteString("\n")
return nil
}
// tcpSackData implements vfs.WritableDynamicBytesSource for
// /proc/sys/net/tcp_sack.
//
// +stateify savable
type tcpSackData struct {
kernfs.DynamicBytesFile
stack inet.Stack `state:"wait"`
enabled *bool
}
var _ vfs.WritableDynamicBytesSource = (*tcpSackData)(nil)
// Generate implements vfs.DynamicBytesSource.
func (d *tcpSackData) Generate(ctx context.Context, buf *bytes.Buffer) error {
if d.enabled == nil {
sack, err := d.stack.TCPSACKEnabled()
if err != nil {
return err
}
d.enabled = &sack
}
val := "0\n"
if *d.enabled {
// Technically, this is not quite compatible with Linux. Linux stores these
// as an integer, so if you write "2" into tcp_sack, you should get 2 back.
// Tough luck.
val = "1\n"
}
buf.WriteString(val)
return nil
}
func (d *tcpSackData) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
if offset != 0 {
// No need to handle partial writes thus far.
return 0, syserror.EINVAL
}
if src.NumBytes() == 0 {
return 0, nil
}
// Limit the amount of memory allocated.
src = src.TakeFirst(usermem.PageSize - 1)
var v int32
n, err := usermem.CopyInt32StringInVec(ctx, src.IO, src.Addrs, &v, src.Opts)
if err != nil {
return n, err
}
if d.enabled == nil {
d.enabled = new(bool)
}
*d.enabled = v != 0
return n, d.stack.SetTCPSACKEnabled(*d.enabled)
}
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