github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/fs/tty/terminal.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 tty
    16  
    17  import (
    18  	"github.com/SagerNet/gvisor/pkg/abi/linux"
    19  	"github.com/SagerNet/gvisor/pkg/context"
    20  	"github.com/SagerNet/gvisor/pkg/marshal/primitive"
    21  	"github.com/SagerNet/gvisor/pkg/refs"
    22  	"github.com/SagerNet/gvisor/pkg/sentry/arch"
    23  	"github.com/SagerNet/gvisor/pkg/sentry/kernel"
    24  )
    25  
    26  // LINT.IfChange
    27  
    28  // Terminal is a pseudoterminal.
    29  //
    30  // +stateify savable
    31  type Terminal struct {
    32  	refs.AtomicRefCount
    33  
    34  	// n is the terminal index. It is immutable.
    35  	n uint32
    36  
    37  	// d is the containing directory. It is immutable.
    38  	d *dirInodeOperations
    39  
    40  	// ld is the line discipline of the terminal. It is immutable.
    41  	ld *lineDiscipline
    42  
    43  	// masterKTTY contains the controlling process of the master end of
    44  	// this terminal. This field is immutable.
    45  	masterKTTY *kernel.TTY
    46  
    47  	// replicaKTTY contains the controlling process of the replica end of this
    48  	// terminal. This field is immutable.
    49  	replicaKTTY *kernel.TTY
    50  }
    51  
    52  func newTerminal(ctx context.Context, d *dirInodeOperations, n uint32) *Terminal {
    53  	termios := linux.DefaultReplicaTermios
    54  	t := Terminal{
    55  		d:           d,
    56  		n:           n,
    57  		ld:          newLineDiscipline(termios),
    58  		masterKTTY:  &kernel.TTY{Index: n},
    59  		replicaKTTY: &kernel.TTY{Index: n},
    60  	}
    61  	t.EnableLeakCheck("tty.Terminal")
    62  	return &t
    63  }
    64  
    65  // setControllingTTY makes tm the controlling terminal of the calling thread
    66  // group.
    67  func (tm *Terminal) setControllingTTY(ctx context.Context, args arch.SyscallArguments, isMaster bool, readable bool) error {
    68  	task := kernel.TaskFromContext(ctx)
    69  	if task == nil {
    70  		panic("setControllingTTY must be called from a task context")
    71  	}
    72  
    73  	steal := args[2].Int() == 1
    74  	return task.ThreadGroup().SetControllingTTY(tm.tty(isMaster), steal, readable)
    75  }
    76  
    77  // releaseControllingTTY removes tm as the controlling terminal of the calling
    78  // thread group.
    79  func (tm *Terminal) releaseControllingTTY(ctx context.Context, args arch.SyscallArguments, isMaster bool) error {
    80  	task := kernel.TaskFromContext(ctx)
    81  	if task == nil {
    82  		panic("releaseControllingTTY must be called from a task context")
    83  	}
    84  
    85  	return task.ThreadGroup().ReleaseControllingTTY(tm.tty(isMaster))
    86  }
    87  
    88  // foregroundProcessGroup gets the process group ID of tm's foreground process.
    89  func (tm *Terminal) foregroundProcessGroup(ctx context.Context, args arch.SyscallArguments, isMaster bool) (uintptr, error) {
    90  	task := kernel.TaskFromContext(ctx)
    91  	if task == nil {
    92  		panic("foregroundProcessGroup must be called from a task context")
    93  	}
    94  
    95  	ret, err := task.ThreadGroup().ForegroundProcessGroup(tm.tty(isMaster))
    96  	if err != nil {
    97  		return 0, err
    98  	}
    99  
   100  	// Write it out to *arg.
   101  	retP := primitive.Int32(ret)
   102  	_, err = retP.CopyOut(task, args[2].Pointer())
   103  	return 0, err
   104  }
   105  
   106  // foregroundProcessGroup sets tm's foreground process.
   107  func (tm *Terminal) setForegroundProcessGroup(ctx context.Context, args arch.SyscallArguments, isMaster bool) (uintptr, error) {
   108  	task := kernel.TaskFromContext(ctx)
   109  	if task == nil {
   110  		panic("setForegroundProcessGroup must be called from a task context")
   111  	}
   112  
   113  	// Read in the process group ID.
   114  	var pgid primitive.Int32
   115  	if _, err := pgid.CopyIn(task, args[2].Pointer()); err != nil {
   116  		return 0, err
   117  	}
   118  
   119  	ret, err := task.ThreadGroup().SetForegroundProcessGroup(tm.tty(isMaster), kernel.ProcessGroupID(pgid))
   120  	return uintptr(ret), err
   121  }
   122  
   123  func (tm *Terminal) tty(isMaster bool) *kernel.TTY {
   124  	if isMaster {
   125  		return tm.masterKTTY
   126  	}
   127  	return tm.replicaKTTY
   128  }
   129  
   130  // LINT.ThenChange(../../fsimpl/devpts/terminal.go)