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libct.Start: fix locking, do not allow a second container init #4271

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merged 3 commits into from
Jun 11, 2024
Merged

libct.Start: fix locking, do not allow a second container init #4271

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304a4c0
libct: createExecFifo: rm unneeded os.Stat
kolyshkin May 7, 2024
e3e1072
libct: fix locking in Start/Run/Exec
kolyshkin May 7, 2024
42cea2e
libct: don't allow to start second init process
kolyshkin May 7, 2024
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40 changes: 21 additions & 19 deletions libcontainer/container_linux.go
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Original file line number Diff line number Diff line change
Expand Up @@ -204,28 +204,16 @@ func (c *Container) Set(config configs.Config) error {
func (c *Container) Start(process *Process) error {
c.m.Lock()
defer c.m.Unlock()
if c.config.Cgroups.Resources.SkipDevices {
return errors.New("can't start container with SkipDevices set")
}
if process.Init {
if err := c.createExecFifo(); err != nil {
return err
}
}
if err := c.start(process); err != nil {
if process.Init {
c.deleteExecFifo()
}
return err
}
return nil
return c.start(process)
}

// Run immediately starts the process inside the container. Returns an error if
// the process fails to start. It does not block waiting for the exec fifo
// after start returns but opens the fifo after start returns.
func (c *Container) Run(process *Process) error {
if err := c.Start(process); err != nil {
c.m.Lock()
defer c.m.Unlock()
if err := c.start(process); err != nil {
return err
}
if process.Init {
Expand Down Expand Up @@ -314,6 +302,23 @@ type openResult struct {
}

func (c *Container) start(process *Process) (retErr error) {
if c.config.Cgroups.Resources.SkipDevices {
return errors.New("can't start container with SkipDevices set")
}
if process.Init {
if c.initProcessStartTime != 0 {
return errors.New("container already has init process")
}
if err := c.createExecFifo(); err != nil {
return err
}
defer func() {
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@lifubang lifubang Jun 10, 2024 •
edited
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Maybe this defer should be moved to the position before createExecFifo, please see #4319.
I don't know whether this PR(4271) should be backported to release-1.1 branch or not, so I opened #4319(seems need backport), feel free to close it.

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My suggestion change is unneeded Once #4319 merged.

if retErr != nil {
c.deleteExecFifo()
}
}()
}

parent, err := c.newParentProcess(process)
if err != nil {
return fmt.Errorf("unable to create new parent process: %w", err)
Expand Down Expand Up @@ -417,9 +422,6 @@ func (c *Container) createExecFifo() error {
}

fifoName := filepath.Join(c.stateDir, execFifoFilename)
if _, err := os.Stat(fifoName); err == nil {
return fmt.Errorf("exec fifo %s already exists", fifoName)
}
if err := unix.Mkfifo(fifoName, 0o622); err != nil {
return &os.PathError{Op: "mkfifo", Path: fifoName, Err: err}
}
Expand Down
2 changes: 0 additions & 2 deletions libcontainer/integration/execin_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -115,7 +115,6 @@ func testExecInRlimit(t *testing.T, userns bool) {
// increase process rlimit higher than container rlimit to test per-process limit
{Type: unix.RLIMIT_NOFILE, Hard: 1026, Soft: 1026},
},
Init: true,
}
err = container.Run(ps)
ok(t, err)
Expand Down Expand Up @@ -359,7 +358,6 @@ func TestExecInEnvironment(t *testing.T) {
Stdin: buffers.Stdin,
Stdout: buffers.Stdout,
Stderr: buffers.Stderr,
Init: true,
}
err = container.Run(process2)
ok(t, err)
Expand Down
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