From 2b4a401aa922cff2e12fa556ff7c4c5b6b6594cb Mon Sep 17 00:00:00 2001
From: whokilleddb <whokilleddb@gmail.com>
Date: Fri, 18 Feb 2022 01:57:20 +0530
Subject: [PATCH] Set hostname inside namespace

---
 include/networkns.h |  2 +-
 include/uts.h       |  5 +++++
 src/isolate.c       | 41 +++++++++++++++++++++++++++++++++++++++++
 src/networkns.c     |  6 ++++--
 4 files changed, 51 insertions(+), 3 deletions(-)
 create mode 100644 include/uts.h

diff --git a/include/networkns.h b/include/networkns.h
index b4eec38..c59acc0 100644
--- a/include/networkns.h
+++ b/include/networkns.h
@@ -17,4 +17,4 @@ int interface_up(char *ifname, char *ip, char *netmask, short if_flags);
 int ns_fd(int pid);
 int add_route();
 int create_veth(int child_pid);
-#endif
\ No newline at end of file
+#endif
diff --git a/include/uts.h b/include/uts.h
new file mode 100644
index 0000000..981d317
--- /dev/null
+++ b/include/uts.h
@@ -0,0 +1,5 @@
+#pragma once
+#ifndef __UTS_NS
+#define __UTS_NS
+#define HOSTNAME "isolate" // Hostname to be used inside the new namespace
+#endif
\ No newline at end of file
diff --git a/src/isolate.c b/src/isolate.c
index b4bd32f..66e266c 100644
--- a/src/isolate.c
+++ b/src/isolate.c
@@ -12,6 +12,7 @@
 
 // User-defined headers
 #include "utils.h"
+#include "uts.h"
 #include "mountns.h"
 #include "userns.h"
 #include "networkns.h"
@@ -49,11 +50,39 @@ void print_isolated_cmd(int argc, char **argv){
     fprintf(stdout,"\n");
 }
 
+
+// Set hostname and prepare /etc/hostname
+int configure_hostname(){
+    // Set hostname for new namespace
+    if (sethostname(HOSTNAME,sizeof(HOSTNAME)) != 0){
+        fprintf(stderr,"["RED("!")"] Failed to set Hostname with "RED("sethostname()")"\n");
+        return -1;
+    }
+
+    // Write to /etc/hostname
+    FILE *fp = fopen("/etc/hostname","w");
+    if(fp == NULL){
+        fprintf(stderr,"["RED("!")"] Failed open "RED("/etc/hostname")" for writing\n");
+        return -1;
+    }
+    if(fprintf(fp,"%s\n",HOSTNAME) < 0){
+        fprintf(stderr,"["RED("!")"] Failed to write to "RED("/etc/hostname")"\n");
+        fclose(fp);
+        return -1;
+    }
+    if (fclose(fp) != 0){
+        fprintf(stderr,"["RED("!")"] Failed to close "RED("/etc/hostname")" after writing\n");
+        return -1;
+    }
+    return 0;
+}
+
 // Child process to be called to run a command 
 int cmd_exec(void *arg){
     // Send a SIGKILL if the isolated process dies
     if (prctl(PR_SET_PDEATHSIG, SIGKILL)<0){
         fprintf(stderr,"[" RED("!") "] Cannot Set" RED("prctl()")"\n");
+        exit(EXIT_FAILURE);
         return -1;
     }
 
@@ -64,25 +93,36 @@ int cmd_exec(void *arg){
     char buf[2];
     if(read(params->fd[0],buf,2)!= 2){
         fprintf(stderr, "[" RED("!") "] Failed to read from pipe while awaiting "RED("'setup done'")" from main");
+        exit(EXIT_FAILURE);
         return -1;
     }
 
     // Prepare MOUNT namespace
     if (prepare_mountns() != 0){
         fprintf(stderr,"[" RED("!") "] Failed to create "RED("MOUNT") " namespace\n");
+        exit(EXIT_FAILURE);
         return -1;
     }
     fprintf(stdout,"[" GREEN("i") "] Successfully created " GREEN("MOUNT") " namespace\n");
 
+    // Set hostname for new namespace
+    if (configure_hostname() != 0){
+        fprintf(stderr,"["RED("!")"] Could not set hostname inside new namespace\n");
+        exit(EXIT_FAILURE);
+        return -1;
+    }
+
     // Close reading end of the pipe once done
     if(close(params->fd[0])){
         fprintf(stderr, "[" RED("!") "] Failed to close pipe\n");
+        exit(EXIT_FAILURE);
         return -1;
     }
 
     // Drop superuser privileges
     if ((setuid(0)==-1) || setgid(0) == -1){
         fprintf(stderr, "[" RED("!") "] Could not set privileges\n");
+        exit(EXIT_FAILURE);
         return -1;
     }
 
@@ -91,6 +131,7 @@ int cmd_exec(void *arg){
 
     if (execvp(cmd,argv)==-1){
         fprintf(stderr,"[" RED("!")"] Cannot execute command in Isolation :(\n");
+        exit(EXIT_FAILURE); 
         return -1;
     }
 
diff --git a/src/networkns.c b/src/networkns.c
index 74c489c..59a14b3 100644
--- a/src/networkns.c
+++ b/src/networkns.c
@@ -195,6 +195,8 @@ int  prepare_networkns(int child_pid){
         fprintf(stderr, "["RED("!")"] Could not setup %s interface\n", VETH1);
         return -1;
     }
+
+    // Add route via default gateway inside namespace
     if (add_route() != 0){
         fprintf(stderr, "["RED("!")"] Failed to add route\n");
         return -1;
@@ -205,8 +207,8 @@ int  prepare_networkns(int child_pid){
         fprintf(stderr,"["RED("!")"] Failed to move thread back to host namespace\n");
         return -1;
     }
-    
+
     close(host_fd);
     close(child_fd);
     return 0;
-}
\ No newline at end of file
+}