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[Bug 1926246] [NEW] chrome based apps can not be run under qemu user mod


From: Wind Li
Subject: [Bug 1926246] [NEW] chrome based apps can not be run under qemu user mode
Date: Tue, 27 Apr 2021 05:24:38 -0000

Public bug reported:

chrome uses /proc/self/exe to fork render process.
Here a simple code to reproduce the issue. It's output parent then child but 
failed with qemu: unknown option 'type=renderer'.

Maybe we can modify exec syscall to replace /proc/self/exe to the real
path.

//gcc -o self self.c 
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
int main(int argc, char** argv) {
  if(argc==1){
    printf ("parent\n");
        if ( fork() == 0 )
    {
        return execl("/proc/self/exe","/proc/self/exe", "--type=renderer",NULL);
    }
  } else {
    printf ("child\n");
  }
  return 0;
}

similar reports:
https://github.com/AppImage/AppImageKit/issues/965  
https://github.com/golang/go/issues/42080  

Workardound:
compile chrome or your chrome based app with a patch to 
content/common/child_process_host_impl.cc:GetChildPath, get the realpath of 
/proc/self/exe:  

diff --git a/content/common/child_process_host_impl.cc 
b/content/common/child_process_host_impl.cc
index bc78aba80ac8..9fab74d3bae8 100644
--- a/content/common/child_process_host_impl.cc
+++ b/content/common/child_process_host_impl.cc
@@ -60,8 +60,12 @@ base::FilePath ChildProcessHost::GetChildPath(int flags) {
 #if defined(OS_LINUX)
   // Use /proc/self/exe rather than our known binary path so updates
   // can't swap out the binary from underneath us.
-  if (child_path.empty() && flags & CHILD_ALLOW_SELF)
-    child_path = base::FilePath(base::kProcSelfExe);
+  if (child_path.empty() && flags & CHILD_ALLOW_SELF) {
+    if (!ReadSymbolicLink(base::FilePath(base::kProcSelfExe), &child_path)) {
+      NOTREACHED() << "Unable to resolve " << base::kProcSelfExe << ".";
+      child_path = base::FilePath(base::kProcSelfExe);
+    }
+  }
 #endif

   // On most platforms, the child executable is the same as the current

** Affects: qemu
     Importance: Undecided
         Status: New

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1926246

Title:
  chrome based apps can not be run under qemu user mode

Status in QEMU:
  New

Bug description:
  chrome uses /proc/self/exe to fork render process.
  Here a simple code to reproduce the issue. It's output parent then child but 
failed with qemu: unknown option 'type=renderer'.

  Maybe we can modify exec syscall to replace /proc/self/exe to the real
  path.

  //gcc -o self self.c 
  #include <stdio.h>
  #include <sys/types.h>
  #include <unistd.h>
  int main(int argc, char** argv) {
    if(argc==1){
      printf ("parent\n");
        if ( fork() == 0 )
      {
          return execl("/proc/self/exe","/proc/self/exe", 
"--type=renderer",NULL);
      }
    } else {
      printf ("child\n");
    }
    return 0;
  }

  similar reports:
  https://github.com/AppImage/AppImageKit/issues/965  
  https://github.com/golang/go/issues/42080  

  Workardound:
  compile chrome or your chrome based app with a patch to 
content/common/child_process_host_impl.cc:GetChildPath, get the realpath of 
/proc/self/exe:  

  diff --git a/content/common/child_process_host_impl.cc 
b/content/common/child_process_host_impl.cc
  index bc78aba80ac8..9fab74d3bae8 100644
  --- a/content/common/child_process_host_impl.cc
  +++ b/content/common/child_process_host_impl.cc
  @@ -60,8 +60,12 @@ base::FilePath ChildProcessHost::GetChildPath(int flags) {
   #if defined(OS_LINUX)
     // Use /proc/self/exe rather than our known binary path so updates
     // can't swap out the binary from underneath us.
  -  if (child_path.empty() && flags & CHILD_ALLOW_SELF)
  -    child_path = base::FilePath(base::kProcSelfExe);
  +  if (child_path.empty() && flags & CHILD_ALLOW_SELF) {
  +    if (!ReadSymbolicLink(base::FilePath(base::kProcSelfExe), &child_path)) {
  +      NOTREACHED() << "Unable to resolve " << base::kProcSelfExe << ".";
  +      child_path = base::FilePath(base::kProcSelfExe);
  +    }
  +  }
   #endif

     // On most platforms, the child executable is the same as the
  current

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