Why would creating a user namespace with size 1 work but size >1 fail
I am experimenting with unprivileged linux containers and I am writing a Go program that creates a minimalist container. The program forks itself and creates namespaces in the process. However for some reason if I set the user namespace size to greater than 1, it fails when running as a regular user.
cmd := exec.Command("/proc/self/exe", "run-container")
cmd.SysProcAttr = &syscall.SysProcAttr{
Cloneflags: syscall.CLONE_NEWUSER | syscall.CLONE_NEWUTS | syscall.CLONE_NEWPID | syscall.CLONE_NEWNS,
Unshareflags: syscall.CLONE_NEWNS,
UidMappings: syscall.SysProcIDMap{
{
ContainerID: 0,
HostID: os.Getuid(),
Size: 1, // set this to 2 or more and it fails
},
},
GidMappings: syscall.SysProcIDMap{
{
ContainerID: 0,
HostID: os.Getgid(),
Size: 1,
},
},
}
// other flags: CLONE_NEWNET, CLONE_NEWIPC, CLONE_NEWCGROUP, CLONE_NEWUSER,
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
err := cmd.Run()
if err != nil {
fmt.Println("ERROR: parent cmd.Run", err)
os.Exit(1)
}
The code above (along with all the other stuff like pivot_root etc.. ) works fine. But the moment I set Size to 2, it bombs:
ERROR: parent cmd.Run fork/exec /proc/self/exe: operation not permitted
This seems to be a capabilities issue because when I run as root it works.
Or it has something to do with something else. I can't figure it out.
Here is my /etc/subuid should it help:
lxd:1000:1
root:1000:1
lxd:100000:65536
root:100000:65536
developer:165536:65536
mounter:231072:65536
Thanks!
linux userns
asked 3 mins ago
teleclimberteleclimber
1
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I am experimenting with unprivileged linux containers and I am writing a Go program that creates a minimalist container. The program forks itself and creates namespaces in the process. However for some reason if I set the user namespace size to greater than 1, it fails when running as a regular user.
cmd := exec.Command("/proc/self/exe", "run-container")
cmd.SysProcAttr = &syscall.SysProcAttr{
Cloneflags: syscall.CLONE_NEWUSER | syscall.CLONE_NEWUTS | syscall.CLONE_NEWPID | syscall.CLONE_NEWNS,
Unshareflags: syscall.CLONE_NEWNS,
UidMappings: syscall.SysProcIDMap{
{
ContainerID: 0,
HostID: os.Getuid(),
Size: 1, // set this to 2 or more and it fails
},
},
GidMappings: syscall.SysProcIDMap{
{
ContainerID: 0,
HostID: os.Getgid(),
Size: 1,
},
},
}
// other flags: CLONE_NEWNET, CLONE_NEWIPC, CLONE_NEWCGROUP, CLONE_NEWUSER,
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
err := cmd.Run()
if err != nil {
fmt.Println("ERROR: parent cmd.Run", err)
os.Exit(1)
}
The code above (along with all the other stuff like pivot_root etc.. ) works fine. But the moment I set Size to 2, it bombs:
ERROR: parent cmd.Run fork/exec /proc/self/exe: operation not permitted
This seems to be a capabilities issue because when I run as root it works.
Or it has something to do with something else. I can't figure it out.
Here is my /etc/subuid should it help:
lxd:1000:1
root:1000:1
lxd:100000:65536
root:100000:65536
developer:165536:65536
mounter:231072:65536
Thanks!
linux userns
asked 3 mins ago
teleclimberteleclimber
1
New contributor
teleclimber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I am experimenting with unprivileged linux containers and I am writing a Go program that creates a minimalist container. The program forks itself and creates namespaces in the process. However for some reason if I set the user namespace size to greater than 1, it fails when running as a regular user.
cmd := exec.Command("/proc/self/exe", "run-container")
cmd.SysProcAttr = &syscall.SysProcAttr{
Cloneflags: syscall.CLONE_NEWUSER | syscall.CLONE_NEWUTS | syscall.CLONE_NEWPID | syscall.CLONE_NEWNS,
Unshareflags: syscall.CLONE_NEWNS,
UidMappings: syscall.SysProcIDMap{
{
ContainerID: 0,
HostID: os.Getuid(),
Size: 1, // set this to 2 or more and it fails
},
},
GidMappings: syscall.SysProcIDMap{
{
ContainerID: 0,
HostID: os.Getgid(),
Size: 1,
},
},
}
// other flags: CLONE_NEWNET, CLONE_NEWIPC, CLONE_NEWCGROUP, CLONE_NEWUSER,
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
err := cmd.Run()
if err != nil {
fmt.Println("ERROR: parent cmd.Run", err)
os.Exit(1)
}
The code above (along with all the other stuff like pivot_root etc.. ) works fine. But the moment I set Size to 2, it bombs:
ERROR: parent cmd.Run fork/exec /proc/self/exe: operation not permitted
This seems to be a capabilities issue because when I run as root it works.
Or it has something to do with something else. I can't figure it out.
Here is my /etc/subuid should it help:
lxd:1000:1
root:1000:1
lxd:100000:65536
root:100000:65536
developer:165536:65536
mounter:231072:65536
Thanks!
linux userns
asked 3 mins ago
teleclimberteleclimber
1
New contributor
teleclimber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I am experimenting with unprivileged linux containers and I am writing a Go program that creates a minimalist container. The program forks itself and creates namespaces in the process. However for some reason if I set the user namespace size to greater than 1, it fails when running as a regular user.
cmd := exec.Command("/proc/self/exe", "run-container")
cmd.SysProcAttr = &syscall.SysProcAttr{
Cloneflags: syscall.CLONE_NEWUSER | syscall.CLONE_NEWUTS | syscall.CLONE_NEWPID | syscall.CLONE_NEWNS,
Unshareflags: syscall.CLONE_NEWNS,
UidMappings: syscall.SysProcIDMap{
{
ContainerID: 0,
HostID: os.Getuid(),
Size: 1, // set this to 2 or more and it fails
},
},
GidMappings: syscall.SysProcIDMap{
{
ContainerID: 0,
HostID: os.Getgid(),
Size: 1,
},
},
}
// other flags: CLONE_NEWNET, CLONE_NEWIPC, CLONE_NEWCGROUP, CLONE_NEWUSER,
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
err := cmd.Run()
if err != nil {
fmt.Println("ERROR: parent cmd.Run", err)
os.Exit(1)
}
The code above (along with all the other stuff like pivot_root etc.. ) works fine. But the moment I set Size to 2, it bombs:
ERROR: parent cmd.Run fork/exec /proc/self/exe: operation not permitted
This seems to be a capabilities issue because when I run as root it works.
Or it has something to do with something else. I can't figure it out.
Here is my /etc/subuid should it help:
lxd:1000:1
root:1000:1
lxd:100000:65536
root:100000:65536
developer:165536:65536
mounter:231072:65536
Thanks!
linux userns
linux userns
asked 3 mins ago
teleclimberteleclimber
1
New contributor
teleclimber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 3 mins ago
teleclimberteleclimber
1
New contributor
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asked 3 mins ago
teleclimberteleclimber
1
New contributor
teleclimber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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asked 3 mins ago
teleclimberteleclimber
1
asked 3 mins ago
teleclimberteleclimber
1
1
New contributor
teleclimber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
teleclimber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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