From 607a892f2e3e6e19109bf51969f0e459483aaa7c Mon Sep 17 00:00:00 2001
From: "fupan.lfp" <fupan.lfp@antfin.com>
Date: Wed, 6 Jan 2021 16:05:49 +0800
Subject: [PATCH] rustjail: fix the issue of bind mount /dev

In case the container rootfs's /dev was overrided
by binding mount from another directory, then there's
no need to create the default devices nodes and symlinks
in /dev.

Fixes: #692

Signed-off-by: fupan.lfp <fupan.lfp@antfin.com>
---
 src/agent/rustjail/src/mount.rs | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/agent/rustjail/src/mount.rs b/src/agent/rustjail/src/mount.rs
index 1942fcc5b8..5f4c9e26d3 100644
--- a/src/agent/rustjail/src/mount.rs
+++ b/src/agent/rustjail/src/mount.rs
@@ -185,6 +185,7 @@ pub fn init_rootfs(
         None::<&str>,
     )?;
 
+    let mut bind_mount_dev = false;
     for m in &spec.mounts {
         let (mut flags, data) = parse_mount(&m);
         if !m.destination.starts_with("/") || m.destination.contains("..") {
@@ -198,6 +199,9 @@ pub fn init_rootfs(
             mount_cgroups(cfd_log, &m, rootfs, flags, &data, cpath, mounts)?;
         } else {
             if m.destination == "/dev" {
+                if m.r#type == "bind" {
+                    bind_mount_dev = true;
+                }
                 flags &= !MsFlags::MS_RDONLY;
             }
 
@@ -239,9 +243,14 @@ pub fn init_rootfs(
     let olddir = unistd::getcwd()?;
     unistd::chdir(rootfs)?;
 
-    default_symlinks()?;
-    create_devices(&linux.devices, bind_device)?;
-    ensure_ptmx()?;
+    // in case the /dev directory was binded mount from guest,
+    // then there's no need to create devices nodes and symlinks
+    // in /dev.
+    if !bind_mount_dev {
+        default_symlinks()?;
+        create_devices(&linux.devices, bind_device)?;
+        ensure_ptmx()?;
+    }
 
     unistd::chdir(&olddir)?;