Re: [patch -mm 2/4] mqueue namespace : add unshare support

From: Pavel Emelyanov
Date: Wed Nov 28 2007 - 12:33:41 EST

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Cedric Le Goater wrote:
> From: Cedric Le Goater <clg@xxxxxxxxxx>
>
> This patch includes the mqueue namespace in the nsproxy object. It
> also adds the support of unshare() and clone() with a new clone flag
> CLONE_NEWMQ (1 bit left in the clone flags !)
>
> CLONE_NEWMQ is required to be cloned or unshared along with CLONE_NEWNS.
> This is to make sure that no user mounts of the internal mqueue fs
> are left behind when the last task exits.
>
> It's totally harmless for the moment because the current code still
> uses the default mqueue namespace object 'init_mq_ns'
>
> Signed-off-by: Cedric Le Goater <clg@xxxxxxxxxx>
> ---
> include/linux/init_task.h | 2 ++
> include/linux/mq_namespace.h | 4 ++++
> include/linux/nsproxy.h | 2 ++
> include/linux/sched.h | 1 +
> ipc/mq_namespace.c | 36 +++++++++++++++++++++++++++++++++++-
> kernel/fork.c | 15 ++++++++++++++-
> kernel/nsproxy.c | 16 ++++++++++++++--
> 7 files changed, 72 insertions(+), 4 deletions(-)
>
> Index: 2.6.24-rc3-mm2/include/linux/init_task.h
> ===================================================================
> --- 2.6.24-rc3-mm2.orig/include/linux/init_task.h
> +++ 2.6.24-rc3-mm2/include/linux/init_task.h
> @@ -10,6 +10,7 @@
> #include <linux/pid_namespace.h>
> #include <linux/user_namespace.h>
> #include <net/net_namespace.h>
> +#include <linux/mq_namespace.h>
>
> #define INIT_FDTABLE \
> { \
> @@ -78,6 +79,7 @@ extern struct nsproxy init_nsproxy;
> INIT_NET_NS(net_ns) \
> INIT_IPC_NS(ipc_ns) \
> .user_ns = &init_user_ns, \
> + INIT_MQ_NS(mq_ns) \
> }
>
> #define INIT_SIGHAND(sighand) { \
> Index: 2.6.24-rc3-mm2/include/linux/sched.h
> ===================================================================
> --- 2.6.24-rc3-mm2.orig/include/linux/sched.h
> +++ 2.6.24-rc3-mm2/include/linux/sched.h
> @@ -27,6 +27,7 @@
> #define CLONE_NEWUSER 0x10000000 /* New user namespace */
> #define CLONE_NEWPID 0x20000000 /* New pid namespace */
> #define CLONE_NEWNET 0x40000000 /* New network namespace */
> +#define CLONE_NEWMQ 0x80000000 /* New posix mqueue namespace */

That's it :) We've run out of clone flags on 32-bit platforms :(

> /*
> * Scheduling policies
> Index: 2.6.24-rc3-mm2/kernel/nsproxy.c
> ===================================================================
> --- 2.6.24-rc3-mm2.orig/kernel/nsproxy.c
> +++ 2.6.24-rc3-mm2/kernel/nsproxy.c
> @@ -93,8 +93,17 @@ static struct nsproxy *create_new_namesp
> goto out_net;
> }
>
> + new_nsp->mq_ns = copy_mq_ns(flags, tsk->nsproxy->mq_ns);
> + if (IS_ERR(new_nsp->mq_ns)) {
> + err = PTR_ERR(new_nsp->mq_ns);
> + goto out_mq;
> + }
> +
> return new_nsp;
>
> +out_mq:
> + if (new_nsp->user_ns)
> + put_user_ns(new_nsp->user_ns);
> out_net:
> if (new_nsp->user_ns)
> put_user_ns(new_nsp->user_ns);
> @@ -131,7 +140,8 @@ int copy_namespaces(unsigned long flags,
> get_nsproxy(old_ns);
>
> if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
> - CLONE_NEWUSER | CLONE_NEWPID | CLONE_NEWNET)))
> + CLONE_NEWUSER | CLONE_NEWPID |
> + CLONE_NEWNET | CLONE_NEWMQ)))
> return 0;
>
> if (!capable(CAP_SYS_ADMIN)) {
> @@ -170,6 +180,8 @@ void free_nsproxy(struct nsproxy *ns)
> put_pid_ns(ns->pid_ns);
> if (ns->user_ns)
> put_user_ns(ns->user_ns);
> + if (ns->mq_ns)
> + put_mq_ns(ns->mq_ns);
> put_net(ns->net_ns);
> kmem_cache_free(nsproxy_cachep, ns);
> }
> @@ -184,7 +196,7 @@ int unshare_nsproxy_namespaces(unsigned
> int err = 0;
>
> if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
> - CLONE_NEWUSER | CLONE_NEWNET)))
> + CLONE_NEWUSER | CLONE_NEWNET | CLONE_NEWMQ)))
> return 0;
>
> if (!capable(CAP_SYS_ADMIN))
> Index: 2.6.24-rc3-mm2/kernel/fork.c
> ===================================================================
> --- 2.6.24-rc3-mm2.orig/kernel/fork.c
> +++ 2.6.24-rc3-mm2/kernel/fork.c
> @@ -1004,6 +1004,13 @@ static struct task_struct *copy_process(
> if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
> return ERR_PTR(-EINVAL);
>
> + /*
> + * mount namespace cannot be unshared when the mqueue
> + * namespace is not

vice versa - mqueue namespace cannot be unshared when the mount one is not ;)

> + */
> + if ((clone_flags & CLONE_NEWMQ) && !(clone_flags & CLONE_NEWNS))
> + return ERR_PTR(-EINVAL);
> +
> retval = security_task_create(clone_flags);
> if (retval)
> goto fork_out;
> @@ -1570,6 +1577,12 @@ static void check_unshare_flags(unsigned
> *flags_ptr |= CLONE_THREAD;
>
> /*
> + * If unsharing mqueue namespace, must also unshare mnt namespace.
> + */
> + if (*flags_ptr & CLONE_NEWMQ)
> + *flags_ptr |= CLONE_NEWNS;
> +
> + /*
> * If unsharing namespace, must also unshare filesystem information.
> */
> if (*flags_ptr & CLONE_NEWNS)
> @@ -1687,7 +1700,7 @@ asmlinkage long sys_unshare(unsigned lon
> if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
> CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
> CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER|
> - CLONE_NEWNET))
> + CLONE_NEWNET|CLONE_NEWMQ))
> goto bad_unshare_out;
>
> if ((err = unshare_thread(unshare_flags)))
> Index: 2.6.24-rc3-mm2/include/linux/nsproxy.h
> ===================================================================
> --- 2.6.24-rc3-mm2.orig/include/linux/nsproxy.h
> +++ 2.6.24-rc3-mm2/include/linux/nsproxy.h
> @@ -8,6 +8,7 @@ struct mnt_namespace;
> struct uts_namespace;
> struct ipc_namespace;
> struct pid_namespace;
> +struct mq_namespace;
>
> /*
> * A structure to contain pointers to all per-process
> @@ -29,6 +30,7 @@ struct nsproxy {
> struct pid_namespace *pid_ns;
> struct user_namespace *user_ns;
> struct net *net_ns;
> + struct mq_namespace *mq_ns;
> };
> extern struct nsproxy init_nsproxy;
>
> Index: 2.6.24-rc3-mm2/ipc/mq_namespace.c
> ===================================================================
> --- 2.6.24-rc3-mm2.orig/ipc/mq_namespace.c
> +++ 2.6.24-rc3-mm2/ipc/mq_namespace.c
> @@ -10,14 +10,48 @@
> */
>
> #include <linux/mq_namespace.h>
> +#include <linux/slab.h>
> +#include <linux/sched.h>
> +#include <linux/err.h>
> +
> +static struct mq_namespace *clone_mq_ns(struct mq_namespace *old_ns)
> +{
> + struct mq_namespace *mq_ns;
> +
> + mq_ns = kmalloc(sizeof(struct mq_namespace), GFP_KERNEL);
> + if (!mq_ns)
> + return ERR_PTR(-ENOMEM);
> +
> + kref_init(&mq_ns->kref);
> + mq_ns->queues_count = 0;
> + mq_ns->queues_max = DFLT_QUEUESMAX;
> + mq_ns->msg_max = DFLT_MSGMAX;
> + mq_ns->msgsize_max = DFLT_MSGSIZEMAX;
> + mq_ns->mnt = NULL;
> + return mq_ns;
> +}
>
> struct mq_namespace *copy_mq_ns(unsigned long flags,
> struct mq_namespace *old_ns)
> {
> + struct mq_namespace *mq_ns;
> +
> BUG_ON(!old_ns);
> - return get_mq_ns(old_ns);
> + get_mq_ns(old_ns);
> +
> + if (!(flags & CLONE_NEWMQ))
> + return old_ns;
> +
> + mq_ns = clone_mq_ns(old_ns);
> +
> + put_mq_ns(old_ns);
> + return mq_ns;
> }
>
> void free_mq_ns(struct kref *kref)
> {
> + struct mq_namespace *ns;
> +
> + ns = container_of(kref, struct mq_namespace, kref);
> + kfree(ns);
> }
> Index: 2.6.24-rc3-mm2/include/linux/mq_namespace.h
> ===================================================================
> --- 2.6.24-rc3-mm2.orig/include/linux/mq_namespace.h
> +++ 2.6.24-rc3-mm2/include/linux/mq_namespace.h
> @@ -2,6 +2,7 @@
> #define _LINUX_MQ_NAMESPACE_H
>
> #include <linux/kref.h>
> +#include <linux/err.h>
>
> struct vfsmount;
>
> @@ -57,6 +58,9 @@ static inline struct mq_namespace *get_m
> static inline struct mq_namespace *copy_mq_ns(unsigned long flags,
> struct mq_namespace *old_ns)
> {
> + if (flags & CLONE_NEWMQ)
> + return ERR_PTR(-EINVAL);
> +
> return old_ns;
> }
>
>
> --

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Next message: Dave Hansen: "Re: [PATCH 06/25] elevate write count open()'d files"
Previous message: Andi Kleen: "Re: [PATCH RFC] [1/9] Core module symbol namespaces code and intro."
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