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// 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 host
import (
"sync"
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
"gvisor.googlesource.com/gvisor/pkg/sentry/context"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
"gvisor.googlesource.com/gvisor/pkg/syserror"
)
// TTYFileOperations implements fs.FileOperations for a host file descriptor
// that wraps a TTY FD.
//
// +stateify savable
type TTYFileOperations struct {
fileOperations
// mu protects the fields below.
mu sync.Mutex
// FGProcessGroup is the foreground process group this TTY. Will be
// nil if not set or if this file has been released.
fgProcessGroup *kernel.ProcessGroup
}
// newTTYFile returns a new fs.File that wraps a TTY FD.
func newTTYFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags, iops *inodeOperations) *fs.File {
return fs.NewFile(ctx, dirent, flags, &TTYFileOperations{
fileOperations: fileOperations{iops: iops},
})
}
// ForegroundProcessGroup returns the foreground process for the TTY. This will
// be nil if the foreground process has not been set or if the file has been
// released.
func (t *TTYFileOperations) ForegroundProcessGroup() *kernel.ProcessGroup {
t.mu.Lock()
defer t.mu.Unlock()
return t.fgProcessGroup
}
// Release implements fs.FileOperations.Release.
func (t *TTYFileOperations) Release() {
t.mu.Lock()
t.fgProcessGroup = nil
t.mu.Unlock()
t.fileOperations.Release()
}
// Ioctl implements fs.FileOperations.Ioctl.
func (t *TTYFileOperations) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
// Ignore arg[0]. This is the real FD:
fd := t.fileOperations.iops.fileState.FD()
ioctl := args[1].Uint64()
switch ioctl {
case linux.TCGETS:
termios, err := ioctlGetTermios(fd)
if err != nil {
return 0, err
}
_, err = usermem.CopyObjectOut(ctx, io, args[2].Pointer(), termios, usermem.IOOpts{
AddressSpaceActive: true,
})
return 0, err
case linux.TCSETS, linux.TCSETSW, linux.TCSETSF:
var termios linux.Termios
if _, err := usermem.CopyObjectIn(ctx, io, args[2].Pointer(), &termios, usermem.IOOpts{
AddressSpaceActive: true,
}); err != nil {
return 0, err
}
err := ioctlSetTermios(fd, ioctl, &termios)
return 0, err
case linux.TIOCGPGRP:
// Args: pid_t *argp
// When successful, equivalent to *argp = tcgetpgrp(fd).
// Get the process group ID of the foreground process group on
// this terminal.
t.mu.Lock()
defer t.mu.Unlock()
if t.fgProcessGroup == nil {
// No process group has been set yet. Let's just lie
// and tell it the process group from the current task.
// The app is probably going to set it to something
// else very soon anyways.
t.fgProcessGroup = kernel.TaskFromContext(ctx).ThreadGroup().ProcessGroup()
}
// Map the ProcessGroup into a ProcessGroupID in the task's PID
// namespace.
pgID := kernel.TaskFromContext(ctx).ThreadGroup().PIDNamespace().IDOfProcessGroup(t.fgProcessGroup)
_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), &pgID, usermem.IOOpts{
AddressSpaceActive: true,
})
return 0, err
case linux.TIOCSPGRP:
// Args: const pid_t *argp
// Equivalent to tcsetpgrp(fd, *argp).
// Set the foreground process group ID of this terminal.
var pgID kernel.ProcessGroupID
if _, err := usermem.CopyObjectIn(ctx, io, args[2].Pointer(), &pgID, usermem.IOOpts{
AddressSpaceActive: true,
}); err != nil {
return 0, err
}
// pgID must be non-negative.
if pgID < 0 {
return 0, syserror.EINVAL
}
// Process group with pgID must exist in this PID namespace.
task := kernel.TaskFromContext(ctx)
pidns := task.PIDNamespace()
pg := pidns.ProcessGroupWithID(pgID)
if pg == nil {
return 0, syserror.ESRCH
}
// Process group must be in same session as calling task's
// process group.
curSession := task.ThreadGroup().ProcessGroup().Session()
curSessionID := pidns.IDOfSession(curSession)
if pidns.IDOfSession(pg.Session()) != curSessionID {
return 0, syserror.EPERM
}
t.mu.Lock()
t.fgProcessGroup = pg
t.mu.Unlock()
return 0, nil
case linux.TIOCGWINSZ:
// Args: struct winsize *argp
// Get window size.
winsize, err := ioctlGetWinsize(fd)
if err != nil {
return 0, err
}
_, err = usermem.CopyObjectOut(ctx, io, args[2].Pointer(), winsize, usermem.IOOpts{
AddressSpaceActive: true,
})
return 0, err
case linux.TIOCSWINSZ:
// Args: const struct winsize *argp
// Set window size.
var winsize linux.Winsize
if _, err := usermem.CopyObjectIn(ctx, io, args[2].Pointer(), &winsize, usermem.IOOpts{
AddressSpaceActive: true,
}); err != nil {
return 0, err
}
err := ioctlSetWinsize(fd, &winsize)
return 0, err
default:
return 0, syserror.ENOTTY
}
}
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