linux-toradex.git/include/linux/nsproxy.h, branch v2.6.26-rc5

Make access to task's nsproxy lighter

2007-10-19T18:53:37+00:00

When someone wants to deal with some other taks's namespaces it has to lock
the task and then to get the desired namespace if the one exists.  This is
slow on read-only paths and may be impossible in some cases.

E.g.  Oleg recently noticed a race between unshare() and the (sent for
review in cgroups) pid namespaces - when the task notifies the parent it
has to know the parent's namespace, but taking the task_lock() is
impossible there - the code is under write locked tasklist lock.

On the other hand switching the namespace on task (daemonize) and releasing
the namespace (after the last task exit) is rather rare operation and we
can sacrifice its speed to solve the issues above.

The access to other task namespaces is proposed to be performed
like this:

     rcu_read_lock();
     nsproxy = task_nsproxy(tsk);
     if (nsproxy != NULL) {
             / *
               * work with the namespaces here
               * e.g. get the reference on one of them
               * /
     } / *
         * NULL task_nsproxy() means that this task is
         * almost dead (zombie)
         * /
     rcu_read_unlock();

This patch has passed the review by Eric and Oleg :) and,
of course, tested.

[clg@fr.ibm.com: fix unshare()]
[ebiederm@xmission.com: Update get_net_ns_by_pid]
Signed-off-by: Pavel Emelyanov 
Signed-off-by: Eric W. Biederman 
Cc: Oleg Nesterov 
Cc: Paul E. McKenney 
Cc: Serge Hallyn 
Signed-off-by: Cedric Le Goater 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: implement namespace tracking subsystem

2007-10-19T18:53:37+00:00

When a task enters a new namespace via a clone() or unshare(), a new cgroup
is created and the task moves into it.

This version names cgroups which are automatically created using
cgroup_clone() as "node_" where pid is the pid of the unsharing or
cloned process.  (Thanks Pavel for the idea) This is safe because if the
process unshares again, it will create

	/cgroups/(...)/node_/node_

The only possibilities (AFAICT) for a -EEXIST on unshare are

	1. pid wraparound
	2. a process fails an unshare, then tries again.

Case 1 is unlikely enough that I ignore it (at least for now).  In case 2, the
node_ will be empty and can be rmdir'ed to make the subsequent unshare()
succeed.

Changelog:
	Name cloned cgroups as "node_".

[clg@fr.ibm.com: fix order of cgroup subsystems in init/Kconfig]
Signed-off-by: Serge E. Hallyn 
Cc: Paul Menage 
Signed-off-by: Cedric Le Goater 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Remove unused member from nsproxy

2007-10-17T15:42:59+00:00

The nslock spinlock is not used in the kernel at all.  Remove it.

Signed-off-by: Pavel Emelyanov 
Acked-by: Serge Hallyn 
Cc: Cedric Le Goater 
Cc: "Eric W. Biederman" 
Cc: Herbert Poetzl 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[NET]: Add a network namespace parameter to tasks

2007-10-10T23:49:04+00:00

This is the network namespace from which all which all sockets
and anything else under user control ultimately get their network
namespace parameters.

Signed-off-by: Eric W. Biederman 
Signed-off-by: David S. Miller

namespace: ensure clone_flags are always stored in an unsigned long

2007-07-16T16:05:48+00:00

While working on unshare support for the network namespace I noticed we
were putting clone flags in an int.  Which is weird because the syscall
uses unsigned long and we at least need an unsigned to properly hold all of
the unshare flags.

So to make the code consistent, this patch updates the code to use
unsigned long instead of int for the clone flags in those places
where we get it wrong today.

Signed-off-by: Eric W. Biederman 
Acked-by: Cedric Le Goater 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

user namespace: add the framework

2007-07-16T16:05:47+00:00

Basically, it will allow a process to unshare its user_struct table,
resetting at the same time its own user_struct and all the associated
accounting.

A new root user (uid == 0) is added to the user namespace upon creation.
Such root users have full privileges and it seems that theses privileges
should be controlled through some means (process capabilities ?)

The unshare is not included in this patch.

Changes since [try #4]:
	- Updated get_user_ns and put_user_ns to accept NULL, and
	  get_user_ns to return the namespace.

Changes since [try #3]:
	- moved struct user_namespace to files user_namespace.{c,h}

Changes since [try #2]:
	- removed struct user_namespace* argument from find_user()

Changes since [try #1]:
	- removed struct user_namespace* argument from find_user()
	- added a root_user per user namespace

Signed-off-by: Cedric Le Goater 
Signed-off-by: Serge E. Hallyn 
Acked-by: Pavel Emelianov 
Cc: Herbert Poetzl 
Cc: Kirill Korotaev 
Cc: Eric W. Biederman 
Cc: Chris Wright 
Cc: Stephen Smalley 
Cc: James Morris 
Cc: Andrew Morgan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge sys_clone()/sys_unshare() nsproxy and namespace handling

2007-05-08T18:15:00+00:00

sys_clone() and sys_unshare() both makes copies of nsproxy and its associated
namespaces.  But they have different code paths.

This patch merges all the nsproxy and its associated namespace copy/clone
handling (as much as possible).  Posted on container list earlier for
feedback.

- Create a new nsproxy and its associated namespaces and pass it back to
  caller to attach it to right process.

- Changed all copy_*_ns() routines to return a new copy of namespace
  instead of attaching it to task->nsproxy.

- Moved the CAP_SYS_ADMIN checks out of copy_*_ns() routines.

- Removed unnessary !ns checks from copy_*_ns() and added BUG_ON()
  just incase.

- Get rid of all individual unshare_*_ns() routines and make use of
  copy_*_ns() instead.

[akpm@osdl.org: cleanups, warning fix]
[clg@fr.ibm.com: remove dup_namespaces() declaration]
[serue@us.ibm.com: fix CONFIG_IPC_NS=n, clone(CLONE_NEWIPC) retval]
[akpm@linux-foundation.org: fix build with CONFIG_SYSVIPC=n]
Signed-off-by: Badari Pulavarty 
Signed-off-by: Serge Hallyn 
Cc: Cedric Le Goater 
Cc: "Eric W. Biederman" 
Cc: 
Signed-off-by: Cedric Le Goater 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Revert "[PATCH] namespaces: fix exit race by splitting exit"

2007-01-30T21:35:18+00:00

This reverts commit 7a238fcba0629b6f2edbcd37458bae56fcf36be5 in
preparation for a better and simpler fix proposed by Eric Biederman
(and fixed up by Serge Hallyn)

Acked-by: Serge E. Hallyn 
Signed-off-by: Linus Torvalds

[PATCH] namespaces: fix exit race by splitting exit

2007-01-30T16:26:44+00:00

Fix exit race by splitting the nsproxy putting into two pieces.  First
piece reduces the nsproxy refcount.  If we dropped the last reference, then
it puts the mnt_ns, and returns the nsproxy as a hint to the caller.  Else
it returns NULL.  The second piece of exiting task namespaces sets
tsk->nsproxy to NULL, and drops the references to other namespaces and
frees the nsproxy only if an nsproxy was passed in.

A little awkward and should probably be reworked, but hopefully it fixes
the NFS oops.

Signed-off-by: Serge E. Hallyn 
Cc: Herbert Poetzl 
Cc: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Cc: Cedric Le Goater 
Cc: Daniel Hokka Zakrisson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Revert "[PATCH] identifier to nsproxy"

2006-12-13T17:05:47+00:00

This reverts commit 373beb35cd6b625e0ba4ad98baace12310a26aa8.

No one is using this identifier yet.  The purpose of this identifier is to
export nsproxy to user space which is wrong.  nsproxy is an internal
implementation optimization, which should keep our fork times from getting
slower as we increase the number of global namespaces you don't have to
share.

Adding a global identifier like this is inappropriate because it makes
namespaces inherently non-recursive, greatly limiting what we can do with
them in the future.

Signed-off-by: Eric W. Biederman 
Cc: Cedric Le Goater 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds