Eric W. Biederman wrote:
Introduce two new system calls:
int nsfd(pid_t pid, unsigned long nstype);
int setns(unsigned long nstype, int fd);
These two new system calls address three specific problems that can
make namespaces hard to work with.
- Namespaces require a dedicated process to pin them in memory.
- It is not possible to use a namespace unless you are the
child of the original creator.
- Namespaces don't have names that userspace can use to talk
about them.
The nsfd() system call returns a file descriptor that can
be used to talk about a specific namespace, and to keep
the specified namespace alive.
The fd returned by nsfd() can be bind mounted as:
mount --bind /proc/self/fd/N /some/filesystem/path
to keep the namespace alive indefinitely as long as
it is mounted.
open works on the fd returned by nsfd() so another
process can get a hold of it and do interesting things.
Overall that allows for persistent naming of namespaces
according to userspace policy.
setns() allows changing the namespace of the current process
to a namespace that originates with nsfd().
Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
---
Is it planned to support all the namespaces for 'nsfd' ?
I mean will it be possible to specify an Or'ed combination of nstype to
grab a reference for several namespaces at a time of the targeted process ?
for example : nsfd( 1234, NSTYPE_NET | NSTYPE_IPC, NSTYPE_MNT)
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