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authorKevin Krakauer <krakauer@google.com>2019-09-19 11:35:27 -0700
committergVisor bot <gvisor-bot@google.com>2019-09-19 11:36:47 -0700
commit0a8a75f3dabaf5c097710c3bb961b67b8ed653b5 (patch)
tree4f28d2550c996b8c10d06ebc511ff0433f47b5f7 /pkg/sentry/fs/tty
parent28f431335b182519f420e026edac8b7bcfd2a40a (diff)
Job control: controlling TTYs and foreground process groups.
Adresses a deadlock with the rolled back change: https://github.com/google/gvisor/commit/b6a5b950d28e0b474fdad160b88bc15314cf9259 Creating a session from an orphaned process group was causing a lock to be acquired twice by a single goroutine. This behavior is addressed, and a test (OrphanRegression) has been added to pty.cc. Implemented the following ioctls: - TIOCSCTTY - set controlling TTY - TIOCNOTTY - remove controlling tty, maybe signal some other processes - TIOCGPGRP - get foreground process group. Also enables tcgetpgrp(). - TIOCSPGRP - set foreground process group. Also enabled tcsetpgrp(). Next steps are to actually turn terminal-generated control characters (e.g. C^c) into signals to the proper process groups, and to send SIGTTOU and SIGTTIN when appropriate. PiperOrigin-RevId: 270088599
Diffstat (limited to 'pkg/sentry/fs/tty')
-rw-r--r--pkg/sentry/fs/tty/BUILD1
-rw-r--r--pkg/sentry/fs/tty/dir.go3
-rw-r--r--pkg/sentry/fs/tty/master.go17
-rw-r--r--pkg/sentry/fs/tty/slave.go13
-rw-r--r--pkg/sentry/fs/tty/terminal.go92
5 files changed, 113 insertions, 13 deletions
diff --git a/pkg/sentry/fs/tty/BUILD b/pkg/sentry/fs/tty/BUILD
index d799de748..25811f668 100644
--- a/pkg/sentry/fs/tty/BUILD
+++ b/pkg/sentry/fs/tty/BUILD
@@ -25,6 +25,7 @@ go_library(
"//pkg/sentry/device",
"//pkg/sentry/fs",
"//pkg/sentry/fs/fsutil",
+ "//pkg/sentry/kernel",
"//pkg/sentry/kernel/auth",
"//pkg/sentry/safemem",
"//pkg/sentry/socket/unix/transport",
diff --git a/pkg/sentry/fs/tty/dir.go b/pkg/sentry/fs/tty/dir.go
index 1d128532b..2f639c823 100644
--- a/pkg/sentry/fs/tty/dir.go
+++ b/pkg/sentry/fs/tty/dir.go
@@ -129,6 +129,9 @@ func newDir(ctx context.Context, m *fs.MountSource) *fs.Inode {
// Release implements fs.InodeOperations.Release.
func (d *dirInodeOperations) Release(ctx context.Context) {
+ d.mu.Lock()
+ defer d.mu.Unlock()
+
d.master.DecRef()
if len(d.slaves) != 0 {
panic(fmt.Sprintf("devpts directory still contains active terminals: %+v", d))
diff --git a/pkg/sentry/fs/tty/master.go b/pkg/sentry/fs/tty/master.go
index 92ec1ca18..19b7557d5 100644
--- a/pkg/sentry/fs/tty/master.go
+++ b/pkg/sentry/fs/tty/master.go
@@ -172,6 +172,19 @@ func (mf *masterFileOperations) Ioctl(ctx context.Context, _ *fs.File, io userme
return 0, mf.t.ld.windowSize(ctx, io, args)
case linux.TIOCSWINSZ:
return 0, mf.t.ld.setWindowSize(ctx, io, args)
+ case linux.TIOCSCTTY:
+ // Make the given terminal the controlling terminal of the
+ // calling process.
+ return 0, mf.t.setControllingTTY(ctx, io, args, true /* isMaster */)
+ case linux.TIOCNOTTY:
+ // Release this process's controlling terminal.
+ return 0, mf.t.releaseControllingTTY(ctx, io, args, true /* isMaster */)
+ case linux.TIOCGPGRP:
+ // Get the foreground process group.
+ return mf.t.foregroundProcessGroup(ctx, io, args, true /* isMaster */)
+ case linux.TIOCSPGRP:
+ // Set the foreground process group.
+ return mf.t.setForegroundProcessGroup(ctx, io, args, true /* isMaster */)
default:
maybeEmitUnimplementedEvent(ctx, cmd)
return 0, syserror.ENOTTY
@@ -185,8 +198,6 @@ func maybeEmitUnimplementedEvent(ctx context.Context, cmd uint32) {
linux.TCSETS,
linux.TCSETSW,
linux.TCSETSF,
- linux.TIOCGPGRP,
- linux.TIOCSPGRP,
linux.TIOCGWINSZ,
linux.TIOCSWINSZ,
linux.TIOCSETD,
@@ -200,8 +211,6 @@ func maybeEmitUnimplementedEvent(ctx context.Context, cmd uint32) {
linux.TIOCEXCL,
linux.TIOCNXCL,
linux.TIOCGEXCL,
- linux.TIOCNOTTY,
- linux.TIOCSCTTY,
linux.TIOCGSID,
linux.TIOCGETD,
linux.TIOCVHANGUP,
diff --git a/pkg/sentry/fs/tty/slave.go b/pkg/sentry/fs/tty/slave.go
index e30266404..944c4ada1 100644
--- a/pkg/sentry/fs/tty/slave.go
+++ b/pkg/sentry/fs/tty/slave.go
@@ -152,9 +152,16 @@ func (sf *slaveFileOperations) Ioctl(ctx context.Context, _ *fs.File, io usermem
case linux.TIOCSCTTY:
// Make the given terminal the controlling terminal of the
// calling process.
- // TODO(b/129283598): Implement once we have support for job
- // control.
- return 0, nil
+ return 0, sf.si.t.setControllingTTY(ctx, io, args, false /* isMaster */)
+ case linux.TIOCNOTTY:
+ // Release this process's controlling terminal.
+ return 0, sf.si.t.releaseControllingTTY(ctx, io, args, false /* isMaster */)
+ case linux.TIOCGPGRP:
+ // Get the foreground process group.
+ return sf.si.t.foregroundProcessGroup(ctx, io, args, false /* isMaster */)
+ case linux.TIOCSPGRP:
+ // Set the foreground process group.
+ return sf.si.t.setForegroundProcessGroup(ctx, io, args, false /* isMaster */)
default:
maybeEmitUnimplementedEvent(ctx, cmd)
return 0, syserror.ENOTTY
diff --git a/pkg/sentry/fs/tty/terminal.go b/pkg/sentry/fs/tty/terminal.go
index b7cecb2ed..ff8138820 100644
--- a/pkg/sentry/fs/tty/terminal.go
+++ b/pkg/sentry/fs/tty/terminal.go
@@ -17,7 +17,10 @@ package tty
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/refs"
+ "gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/context"
+ "gvisor.dev/gvisor/pkg/sentry/kernel"
+ "gvisor.dev/gvisor/pkg/sentry/usermem"
)
// Terminal is a pseudoterminal.
@@ -26,23 +29,100 @@ import (
type Terminal struct {
refs.AtomicRefCount
- // n is the terminal index.
+ // n is the terminal index. It is immutable.
n uint32
- // d is the containing directory.
+ // d is the containing directory. It is immutable.
d *dirInodeOperations
- // ld is the line discipline of the terminal.
+ // ld is the line discipline of the terminal. It is immutable.
ld *lineDiscipline
+
+ // masterKTTY contains the controlling process of the master end of
+ // this terminal. This field is immutable.
+ masterKTTY *kernel.TTY
+
+ // slaveKTTY contains the controlling process of the slave end of this
+ // terminal. This field is immutable.
+ slaveKTTY *kernel.TTY
}
func newTerminal(ctx context.Context, d *dirInodeOperations, n uint32) *Terminal {
termios := linux.DefaultSlaveTermios
t := Terminal{
- d: d,
- n: n,
- ld: newLineDiscipline(termios),
+ d: d,
+ n: n,
+ ld: newLineDiscipline(termios),
+ masterKTTY: &kernel.TTY{},
+ slaveKTTY: &kernel.TTY{},
}
t.EnableLeakCheck("tty.Terminal")
return &t
}
+
+// setControllingTTY makes tm the controlling terminal of the calling thread
+// group.
+func (tm *Terminal) setControllingTTY(ctx context.Context, io usermem.IO, args arch.SyscallArguments, isMaster bool) error {
+ task := kernel.TaskFromContext(ctx)
+ if task == nil {
+ panic("setControllingTTY must be called from a task context")
+ }
+
+ return task.ThreadGroup().SetControllingTTY(tm.tty(isMaster), args[2].Int())
+}
+
+// releaseControllingTTY removes tm as the controlling terminal of the calling
+// thread group.
+func (tm *Terminal) releaseControllingTTY(ctx context.Context, io usermem.IO, args arch.SyscallArguments, isMaster bool) error {
+ task := kernel.TaskFromContext(ctx)
+ if task == nil {
+ panic("releaseControllingTTY must be called from a task context")
+ }
+
+ return task.ThreadGroup().ReleaseControllingTTY(tm.tty(isMaster))
+}
+
+// foregroundProcessGroup gets the process group ID of tm's foreground process.
+func (tm *Terminal) foregroundProcessGroup(ctx context.Context, io usermem.IO, args arch.SyscallArguments, isMaster bool) (uintptr, error) {
+ task := kernel.TaskFromContext(ctx)
+ if task == nil {
+ panic("foregroundProcessGroup must be called from a task context")
+ }
+
+ ret, err := task.ThreadGroup().ForegroundProcessGroup(tm.tty(isMaster))
+ if err != nil {
+ return 0, err
+ }
+
+ // Write it out to *arg.
+ _, err = usermem.CopyObjectOut(ctx, io, args[2].Pointer(), int32(ret), usermem.IOOpts{
+ AddressSpaceActive: true,
+ })
+ return 0, err
+}
+
+// foregroundProcessGroup sets tm's foreground process.
+func (tm *Terminal) setForegroundProcessGroup(ctx context.Context, io usermem.IO, args arch.SyscallArguments, isMaster bool) (uintptr, error) {
+ task := kernel.TaskFromContext(ctx)
+ if task == nil {
+ panic("setForegroundProcessGroup must be called from a task context")
+ }
+
+ // Read in the process group ID.
+ var pgid int32
+ if _, err := usermem.CopyObjectIn(ctx, io, args[2].Pointer(), &pgid, usermem.IOOpts{
+ AddressSpaceActive: true,
+ }); err != nil {
+ return 0, err
+ }
+
+ ret, err := task.ThreadGroup().SetForegroundProcessGroup(tm.tty(isMaster), kernel.ProcessGroupID(pgid))
+ return uintptr(ret), err
+}
+
+func (tm *Terminal) tty(isMaster bool) *kernel.TTY {
+ if isMaster {
+ return tm.masterKTTY
+ }
+ return tm.slaveKTTY
+}