add mount ns support to nsutil (litmuschaos#499)

Signed-off-by: Shubham Chaudhary <[email protected]>

.github/workflows/release.yml

@@ -3,15 +3,15 @@ name: release
 
 on:
   workflow_dispatch:
-    inputs:   
+    inputs:
       release_tag:
         description: 'release tag'
         required: true
       release_title:
         description: 'release title'
         required: false
       release_notes:
-        description: 'release notes'     
+        description: 'release notes'
         required: false
         default: ''
 
@@ -22,6 +22,11 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+        with:
+          qemu-version: '6.0.0'
+
       - name: Build go binary for pause
         run : ./../../build/go-multiarch-build.sh "go build -o ./../../build/_output/pause-linux"
         working-directory: custom/pause
@@ -30,15 +35,30 @@ jobs:
         run : ./../../build/go-multiarch-build.sh "go build -o ./../../build/_output/nsutil-linux"
         working-directory: custom/nsutil
 
+      - name: Build shared libraries for nsutil amd64
+        run: gcc -shared -fPIC nsutil.c -o ./../../build/_output/nsutil_amd64.so
+        working-directory: custom/nsutil
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Build arm64 Docker image
+        run: docker buildx build --platform linux/arm64 -t myapp-arm64 --load .
+        working-directory: custom/nsutil
+
+      - name: Extract compiled binary
+        run: docker create --name myapp-arm64-container myapp-arm64 && docker cp myapp-arm64-container:/app/nsutil.so ./../../build/_output/nsutil_arm64.so
+        working-directory: custom/nsutil
+
       - name: Build go binary for promql-cli
         run : |
           cp custom/promql-cli/promql-linux-amd64 build/_output/
           cp custom/promql-cli/promql-linux-arm64 build/_output/
-          
+
       - name: Build go binary for dns_interceptor
         run : go build -o ./../../build/_output/dns_interceptor
         working-directory: custom/dns_interceptor
-      
+
       - name: create release along with artifact
         uses: ncipollo/release-action@v1
         with:

custom/hardened-alpine/experiment/Dockerfile

@@ -60,6 +60,9 @@ RUN curl -L https://github.com/chaosnative/promql-cli/releases/download/3.0.0-be
 #Installing nsutil cli binaries
 RUN curl -L https://github.com/litmuschaos/test-tools/releases/download/${LITMUS_VERSION}/nsutil-linux-${TARGETARCH} --output /usr/local/bin/nsutil && chmod +x /usr/local/bin/nsutil
 
+#Installing nsutil shared lib
+RUN curl -L https://github.com/litmuschaos/test-tools/releases/download/${LITMUS_VERSION}/nsutil-${TARGETARCH}.so --output /usr/local/lib/nsutil.so && chmod +x /usr/local/lib/nsutil.so
+
 #Installing pause cli binaries
 RUN curl -L https://github.com/litmuschaos/test-tools/releases/download/${LITMUS_VERSION}/pause-linux-${TARGETARCH} --output /usr/local/bin/pause && chmod +x /usr/local/bin/pause
 

custom/nsutil/Dockerfile

@@ -0,0 +1,13 @@
+FROM arm64v8/ubuntu:latest
+
+# Install gcc for compiling C code
+RUN apt-get update && apt-get install -y gcc
+
+# Set the working directory
+WORKDIR /app
+
+# Copy your C code into the container
+COPY nsutil.c /app
+
+# Compile the C code
+RUN gcc -shared -fPIC nsutil.c -o nsutil.so

custom/nsutil/cmd/root.go

@@ -15,10 +15,12 @@ import (
 )
 
 // user and mnt ns not supported
-var ns = []string{"net", "pid", "cgroup", "uts", "ipc"}
-var nsSelected = make([]bool, 6)
-
-var t int // target pid
+var (
+	ns         = []string{"net", "pid", "cgroup", "uts", "ipc", "mnt"}
+	nsSelected = make([]bool, 7)
+	t          int // target pid
+	libPath    string
+)
 
 // rootCmd represents the base command
 var rootCmd = &cobra.Command{
@@ -41,7 +43,9 @@ func init() {
 	rootCmd.PersistentFlags().BoolVarP(&nsSelected[2], "cgroup", "c", false, "cgroup namespace to enter")
 	rootCmd.PersistentFlags().BoolVarP(&nsSelected[3], "uts", "u", false, "uts namespace to enter")
 	rootCmd.PersistentFlags().BoolVarP(&nsSelected[4], "ipc", "i", false, "ipc namespace to enter")
+	rootCmd.PersistentFlags().BoolVarP(&nsSelected[5], "mnt", "m", false, "mnt namespace to enter")
 	rootCmd.PersistentFlags().IntVarP(&t, "target", "t", 0, "target process id (required)")
+	rootCmd.PersistentFlags().StringVar(&libPath, "lib-path", "/usr/local/lib/nsutil.so", "shared library path to be preloaded")
 	err := rootCmd.MarkPersistentFlagRequired("target")
 	if err != nil {
 		log.WithError(err).Fatal("Failed to mark required flag")
@@ -55,6 +59,9 @@ func nsutil(cmd *cobra.Command, args []string) {
 	// target command
 	nCmd := exec.Command(args[0], args[1:]...)
 	nCmd.Env = os.Environ()
+	if nsSelected[5] {
+		nCmd.Env = append(nCmd.Env, fmt.Sprintf("LD_PRELOAD=%s", libPath), fmt.Sprintf("MNT_PATH=%s", fmt.Sprintf("/proc/"+strconv.Itoa(t)+"/ns/mnt")))
+	}
 	nCmd.Stdin = os.Stdin
 	nCmd.Stdout = os.Stdout
 	nCmd.Stderr = os.Stderr
@@ -97,7 +104,7 @@ func nsutil(cmd *cobra.Command, args []string) {
 func getNSFiles() map[string]*os.File {
 	nsMap := map[string]*os.File{}
 	for i, n := range ns {
-		if !nsSelected[i] {
+		if !nsSelected[i] || n == "mnt" {
 			continue
 		}
 		file, err := getFileFromNS("/proc/" + strconv.Itoa(t) + "/ns/" + n)

custom/nsutil/nsutil.c

@@ -0,0 +1,31 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <sys/stat.h>
+
+void nsenter() {
+    char *mnt_path = getenv("MNT_PATH");
+    if (mnt_path != NULL) {
+        int fd = open(mnt_path, O_RDONLY);
+        if (fd == -1) {
+            perror("open");
+            exit(EXIT_FAILURE);
+        }
+
+        int ns = setns(fd, 0);
+        if (ns == -1) {
+            perror("setns");
+            exit(EXIT_FAILURE);
+        }
+    }
+
+    unsetenv("LD_PRELOAD");
+}
+
+__attribute__((constructor)) void ctor() {
+    nsenter();
+}

go.mod

@@ -12,4 +12,5 @@ require (
 	golang.org/x/net v0.0.0-20220225172249-27dd8689420f // indirect
 	golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9 // indirect
 	golang.org/x/text v0.3.7 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -20,5 +20,6 @@ golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=