Add a hook to disable device node creation in a container

If required, this hook creates a modified params file (with ModifyDeviceFiles: 0) in a tmpfs
and mounts this over /proc/driver/nvidia/params.

This prevents device node creation when running tools such as nvidia-smi. In general the
creation of these devices is cosmetic as a container does not have the required cgroup
access for the devices.

Signed-off-by: Evan Lezar <elezar@nvidia.com>
This commit is contained in:
Evan Lezar 2025-02-13 15:09:36 +01:00
parent fdcd250362
commit 0c8723a93a
No known key found for this signature in database
5 changed files with 327 additions and 0 deletions

View File

@ -22,6 +22,7 @@ import (
"github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-cdi-hook/chmod"
symlinks "github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-cdi-hook/create-symlinks"
"github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-cdi-hook/cudacompat"
disabledevicenodemodification "github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-cdi-hook/disable-device-node-modification"
ldcache "github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-cdi-hook/update-ldcache"
"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
)
@ -34,6 +35,7 @@ func New(logger logger.Interface) []*cli.Command {
symlinks.NewCommand(logger),
chmod.NewCommand(logger),
cudacompat.NewCommand(logger),
disabledevicenodemodification.NewCommand(logger),
}
}

View File

@ -0,0 +1,144 @@
/**
# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#
# 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 disabledevicenodemodification
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"os"
"strings"
"github.com/urfave/cli/v2"
"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
"github.com/NVIDIA/nvidia-container-toolkit/internal/oci"
)
const (
nvidiaDriverParamsPath = "/proc/driver/nvidia/params"
)
type options struct {
containerSpec string
}
// NewCommand constructs an disable-device-node-modification subcommand with the specified logger
func NewCommand(logger logger.Interface) *cli.Command {
cfg := options{}
c := cli.Command{
Name: "disable-device-node-modification",
Usage: "Ensure that the /proc/driver/nvidia/params file present in the container does not allow device node modifications.",
Before: func(c *cli.Context) error {
return validateFlags(c, &cfg)
},
Action: func(c *cli.Context) error {
return run(c, &cfg)
},
}
c.Flags = []cli.Flag{
&cli.StringFlag{
Name: "container-spec",
Hidden: true,
Usage: "Specify the path to the OCI container spec. If empty or '-' the spec will be read from STDIN",
Destination: &cfg.containerSpec,
},
}
return &c
}
func validateFlags(c *cli.Context, cfg *options) error {
return nil
}
func run(_ *cli.Context, cfg *options) error {
modifiedParamsFileContents, err := getModifiedNVIDIAParamsContents()
if err != nil {
return fmt.Errorf("failed to get modified params file contents: %w", err)
}
if len(modifiedParamsFileContents) == 0 {
return nil
}
s, err := oci.LoadContainerState(cfg.containerSpec)
if err != nil {
return fmt.Errorf("failed to load container state: %w", err)
}
containerRootDirPath, err := s.GetContainerRoot()
if err != nil {
return fmt.Errorf("failed to determined container root: %w", err)
}
return createParamsFileInContainer(containerRootDirPath, modifiedParamsFileContents)
}
func getModifiedNVIDIAParamsContents() ([]byte, error) {
hostNvidiaParamsFile, err := os.Open(nvidiaDriverParamsPath)
if errors.Is(err, os.ErrNotExist) {
return nil, nil
}
if err != nil {
return nil, fmt.Errorf("failed to load params file: %w", err)
}
defer hostNvidiaParamsFile.Close()
modifiedContents, err := getModifiedParamsFileContentsFromReader(hostNvidiaParamsFile)
if err != nil {
return nil, fmt.Errorf("failed to get modfied params file contents: %w", err)
}
return modifiedContents, nil
}
// getModifiedParamsFileContentsFromReader returns the contents of a modified params file from the specified reader.
func getModifiedParamsFileContentsFromReader(r io.Reader) ([]byte, error) {
var modified bytes.Buffer
scanner := bufio.NewScanner(r)
var requiresModification bool
for scanner.Scan() {
line := scanner.Text()
if strings.HasPrefix(line, "ModifyDeviceFiles: ") {
if line == "ModifyDeviceFiles: 0" {
return nil, nil
}
if line == "ModifyDeviceFiles: 1" {
line = "ModifyDeviceFiles: 0"
requiresModification = true
}
}
if _, err := modified.WriteString(line + "\n"); err != nil {
return nil, fmt.Errorf("failed to create output buffer: %w", err)
}
}
if err := scanner.Err(); err != nil {
return nil, fmt.Errorf("failed to read params file: %w", err)
}
if !requiresModification {
return nil, nil
}
return modified.Bytes(), nil
}

View File

@ -0,0 +1,91 @@
/**
# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#
# 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 disabledevicenodemodification
import (
"bytes"
"testing"
"github.com/stretchr/testify/require"
)
func TestGetModifiedParamsFileContentsFromReader(t *testing.T) {
testCases := map[string]struct {
contents []byte
expectedError error
expectedContents []byte
}{
"no contents": {
contents: nil,
expectedError: nil,
expectedContents: nil,
},
"other contents are ignored": {
contents: []byte(`# Some other content
that we don't care about
`),
expectedError: nil,
expectedContents: nil,
},
"already zero requires no modification": {
contents: []byte("ModifyDeviceFiles: 0"),
expectedError: nil,
expectedContents: nil,
},
"leading spaces require no modification": {
contents: []byte(" ModifyDeviceFiles: 1"),
},
"Trailing spaces require no modification": {
contents: []byte("ModifyDeviceFiles: 1 "),
},
"Not 1 require no modification": {
contents: []byte("ModifyDeviceFiles: 11"),
},
"single line requires modification": {
contents: []byte("ModifyDeviceFiles: 1"),
expectedError: nil,
expectedContents: []byte("ModifyDeviceFiles: 0\n"),
},
"single line with trailing newline requires modification": {
contents: []byte("ModifyDeviceFiles: 1\n"),
expectedError: nil,
expectedContents: []byte("ModifyDeviceFiles: 0\n"),
},
"other content is maintained": {
contents: []byte(`ModifyDeviceFiles: 1
other content
that
is maintained`),
expectedError: nil,
expectedContents: []byte(`ModifyDeviceFiles: 0
other content
that
is maintained
`),
},
}
for description, tc := range testCases {
t.Run(description, func(t *testing.T) {
contents, err := getModifiedParamsFileContentsFromReader(bytes.NewReader(tc.contents))
require.EqualValues(t, tc.expectedError, err)
require.EqualValues(t, string(tc.expectedContents), string(contents))
})
}
}

View File

@ -0,0 +1,63 @@
//go:build linux
/**
# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#
# 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 disabledevicenodemodification
import (
"fmt"
"os"
"path/filepath"
"github.com/opencontainers/runc/libcontainer/utils"
"golang.org/x/sys/unix"
)
func createParamsFileInContainer(containerRootDirPath string, contents []byte) error {
tmpRoot, err := os.MkdirTemp("", "nvct-empty-dir*")
if err != nil {
return fmt.Errorf("failed to create temp root: %w", err)
}
if err := createTmpFs(tmpRoot, len(contents)); err != nil {
return fmt.Errorf("failed to create tmpfs mount for params file: %w", err)
}
modifiedParamsFile, err := os.OpenFile(filepath.Join(tmpRoot, "nvct-params"), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0444)
if err != nil {
return fmt.Errorf("failed to open modified params file: %w", err)
}
defer modifiedParamsFile.Close()
if _, err := modifiedParamsFile.Write(contents); err != nil {
return fmt.Errorf("failed to write temporary params file: %w", err)
}
err = utils.WithProcfd(containerRootDirPath, nvidiaDriverParamsPath, func(nvidiaDriverParamsFdPath string) error {
return unix.Mount(modifiedParamsFile.Name(), nvidiaDriverParamsFdPath, "", unix.MS_BIND|unix.MS_RDONLY|unix.MS_NODEV|unix.MS_PRIVATE|unix.MS_NOSYMFOLLOW, "")
})
if err != nil {
return fmt.Errorf("failed to mount modified params file: %w", err)
}
return nil
}
func createTmpFs(target string, size int) error {
return unix.Mount("tmpfs", target, "tmpfs", 0, fmt.Sprintf("size=%d", size))
}

View File

@ -0,0 +1,27 @@
//go:build !linux
// +build !linux
/**
# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#
# 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 disabledevicenodemodification
import "fmt"
func createParamsFileInContainer(containerRootDirPath string, contents []byte) error {
return fmt.Errorf("not supported")
}