[ABI REVIEW][PATCH 0/8] Namespace file descriptors
luto at mit.edu
Fri Sep 24 06:02:39 PDT 2010
Eric W. Biederman wrote:
> Introduce file for manipulating namespaces and related syscalls.
> int setns(unsigned long nstype, int fd);
> socketat(int nsfd, int family, int type, int protocol);
How does security work? Are there different kinds of fd that give (say) pin-the-namespace permission, socketat permission, and setns permission?
> Netlink attribute:
> IFLA_NS_FD int fd.
> Name space file descriptors 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.
> Opening of the /proc/self/ns/<nstype> files return a file descriptor
> that can be used to talk about a specific namespace, and to keep the
> specified namespace alive.
> /proc/self/ns/<nstype> can be bind mounted as:
> mount --bind /proc/self/ns/net /some/filesystem/path
> to keep the namespace alive as long as the mount exists.
> setns() as a companion to unshare allows changing the namespace
> of the current process, being able to unshare the namespace is
> a requirement.
> There are two primary envisioned uses for this functionality.
> o ``Entering'' an existing container.
> o Allowing multiple network namespaces to be in use at once on
> the same machine, without requiring elaborate infrastructure.
> Overall this received positive reviews on the containers list but this
> needs a wider review of the ABI as this is pretty fundamental kernel
> I have left out the pid namespaces bits for the moment because the pid
> namespace still needs work before it is safe to unshare, and my concern
> at the moment is ensuring the system calls seem reasonable.
> Eric W. Biederman (8):
> ns: proc files for namespace naming policy.
> ns: Introduce the setns syscall
> ns proc: Add support for the network namespace.
> ns proc: Add support for the uts namespace
> ns proc: Add support for the ipc namespace
> ns proc: Add support for the mount namespace
> net: Allow setting the network namespace by fd
> net: Implement socketat.
> fs/namespace.c | 57 +++++++++++++
> fs/proc/Makefile | 1 +
> fs/proc/base.c | 22 +++---
> fs/proc/inode.c | 7 ++
> fs/proc/internal.h | 18 ++++
> fs/proc/namespaces.c | 193 +++++++++++++++++++++++++++++++++++++++++++
> include/linux/if_link.h | 1 +
> include/linux/proc_fs.h | 20 +++++
> include/net/net_namespace.h | 1 +
> ipc/namespace.c | 31 +++++++
> kernel/nsproxy.c | 39 +++++++++
> kernel/utsname.c | 32 +++++++
> net/core/net_namespace.c | 56 +++++++++++++
> net/core/rtnetlink.c | 4 +-
> net/socket.c | 26 ++++++-
> 15 files changed, 494 insertions(+), 14 deletions(-)
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