Re: [PATCH 2/2] proc: Usable inode numbers for the namespace filedescriptors.
From: Serge E. Hallyn
Date: Mon Jun 20 2011 - 12:07:16 EST
Quoting Eric W. Biederman (ebiederm@xxxxxxxxxxxx):
>
> Assign a unique proc inode to each namespace, yielding an
> identifier that userspace can use for identifying a namespace.
>
> This has been a long requested feature and only blocked because
> a naive implementation would put the id in a global space and
> would ultimately require having a namespace for the names of
> namespaces, making migration and certain virtualization tricks
> impossible.
>
> We still don't have per superblock inode numbers for proc, which
> appears necessary for application unaware checkpoint/restart and
> migrations (if the application is using namespace filedescriptors)
> but that is now allowd by the design if it becomes important.
>
> I have preallocated the ipc and uts initial proc inode numbers so
> their structures can be statically initialized.
>
> Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
I've not looked at the setns patches enough, but from what I can see
here it looks good.
Acked-by: Serge Hallyn <serge@xxxxxxxxxx>
thanks,
-serge
> ---
> fs/proc/namespaces.c | 1 +
> include/linux/ipc_namespace.h | 2 ++
> include/linux/proc_fs.h | 4 ++++
> include/linux/utsname.h | 1 +
> include/net/net_namespace.h | 2 ++
> init/version.c | 2 ++
> ipc/msgutil.c | 2 ++
> ipc/namespace.c | 16 ++++++++++++++++
> kernel/utsname.c | 17 ++++++++++++++++-
> net/core/net_namespace.c | 24 ++++++++++++++++++++++++
> 10 files changed, 70 insertions(+), 1 deletions(-)
>
> diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
> index be177f7..ddc2bb4 100644
> --- a/fs/proc/namespaces.c
> +++ b/fs/proc/namespaces.c
> @@ -54,6 +54,7 @@ static struct dentry *proc_ns_instantiate(struct inode *dir,
> ei->ns_ops = ns_ops;
> ei->ns = ns;
>
> + inode->i_ino = ns_ops->inum(ei->ns);
> dentry->d_op = &pid_dentry_operations;
> d_add(dentry, inode);
> /* Close the race of the process dying before we return the dentry */
> diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
> index a6d1655..22a4dc4 100644
> --- a/include/linux/ipc_namespace.h
> +++ b/include/linux/ipc_namespace.h
> @@ -60,6 +60,8 @@ struct ipc_namespace {
>
> /* user_ns which owns the ipc ns */
> struct user_namespace *user_ns;
> +
> + unsigned int proc_inum;
> };
>
> extern struct ipc_namespace init_ipc_ns;
> diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
> index 3067b44..1aee7f0 100644
> --- a/include/linux/proc_fs.h
> +++ b/include/linux/proc_fs.h
> @@ -29,8 +29,11 @@ struct mm_struct;
>
> enum {
> PROC_ROOT_INO = 1,
> + PROC_IPC_INIT_INO = 2,
> + PROC_UTS_INIT_INO = 3,
> };
>
> +
> /*
> * This is not completely implemented yet. The idea is to
> * create an in-memory tree (like the actual /proc filesystem
> @@ -257,6 +260,7 @@ struct proc_ns_operations {
> void *(*get)(struct task_struct *task);
> void (*put)(void *ns);
> int (*install)(struct nsproxy *nsproxy, void *ns);
> + unsigned int (*inum)(void *ns);
> };
> extern const struct proc_ns_operations netns_operations;
> extern const struct proc_ns_operations utsns_operations;
> diff --git a/include/linux/utsname.h b/include/linux/utsname.h
> index 4e5b021..03db764 100644
> --- a/include/linux/utsname.h
> +++ b/include/linux/utsname.h
> @@ -44,6 +44,7 @@ struct uts_namespace {
> struct kref kref;
> struct new_utsname name;
> struct user_namespace *user_ns;
> + unsigned int proc_inum;
> };
> extern struct uts_namespace init_uts_ns;
>
> diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
> index 2bf9ed9..4b85be2 100644
> --- a/include/net/net_namespace.h
> +++ b/include/net/net_namespace.h
> @@ -49,6 +49,8 @@ struct net {
> struct list_head cleanup_list; /* namespaces on death row */
> struct list_head exit_list; /* Use only net_mutex */
>
> + unsigned int proc_inum;
> +
> struct proc_dir_entry *proc_net;
> struct proc_dir_entry *proc_net_stat;
>
> diff --git a/init/version.c b/init/version.c
> index 86fe0cc..58170f1 100644
> --- a/init/version.c
> +++ b/init/version.c
> @@ -12,6 +12,7 @@
> #include <linux/utsname.h>
> #include <generated/utsrelease.h>
> #include <linux/version.h>
> +#include <linux/proc_fs.h>
>
> #ifndef CONFIG_KALLSYMS
> #define version(a) Version_ ## a
> @@ -34,6 +35,7 @@ struct uts_namespace init_uts_ns = {
> .domainname = UTS_DOMAINNAME,
> },
> .user_ns = &init_user_ns,
> + .proc_inum = PROC_UTS_INIT_INO,
> };
> EXPORT_SYMBOL_GPL(init_uts_ns);
>
> diff --git a/ipc/msgutil.c b/ipc/msgutil.c
> index 8b5ce5d..f7da485 100644
> --- a/ipc/msgutil.c
> +++ b/ipc/msgutil.c
> @@ -14,6 +14,7 @@
> #include <linux/slab.h>
> #include <linux/ipc.h>
> #include <linux/ipc_namespace.h>
> +#include <linux/proc_fs.h>
> #include <asm/uaccess.h>
>
> #include "util.h"
> @@ -33,6 +34,7 @@ struct ipc_namespace init_ipc_ns = {
> .mq_msgsize_max = DFLT_MSGSIZEMAX,
> #endif
> .user_ns = &init_user_ns,
> + .proc_inum = PROC_IPC_INIT_INO,
> };
>
> atomic_t nr_ipc_ns = ATOMIC_INIT(1);
> diff --git a/ipc/namespace.c b/ipc/namespace.c
> index ce0a647..cd7f733 100644
> --- a/ipc/namespace.c
> +++ b/ipc/namespace.c
> @@ -26,9 +26,16 @@ static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk,
> if (ns == NULL)
> return ERR_PTR(-ENOMEM);
>
> + err = proc_alloc_inum(&ns->proc_inum);
> + if (err) {
> + kfree(ns);
> + return ERR_PTR(err);
> + }
> +
> atomic_set(&ns->count, 1);
> err = mq_init_ns(ns);
> if (err) {
> + proc_free_inum(ns->proc_inum);
> kfree(ns);
> return ERR_PTR(err);
> }
> @@ -113,6 +120,7 @@ static void free_ipc_ns(struct ipc_namespace *ns)
> */
> ipcns_notify(IPCNS_REMOVED);
> put_user_ns(ns->user_ns);
> + proc_free_inum(ns->proc_inum);
> kfree(ns);
> }
>
> @@ -170,10 +178,18 @@ static int ipcns_install(struct nsproxy *nsproxy, void *ns)
> return 0;
> }
>
> +static unsigned int ipcns_inum(void *vp)
> +{
> + struct ipc_namespace *ns = vp;
> +
> + return ns->proc_inum;
> +}
> +
> const struct proc_ns_operations ipcns_operations = {
> .name = "ipc",
> .type = CLONE_NEWIPC,
> .get = ipcns_get,
> .put = ipcns_put,
> .install = ipcns_install,
> + .inum = ipcns_inum,
> };
> diff --git a/kernel/utsname.c b/kernel/utsname.c
> index bff131b..3ab6a08 100644
> --- a/kernel/utsname.c
> +++ b/kernel/utsname.c
> @@ -36,11 +36,18 @@ static struct uts_namespace *clone_uts_ns(struct task_struct *tsk,
> struct uts_namespace *old_ns)
> {
> struct uts_namespace *ns;
> + int err;
>
> ns = create_uts_ns();
> if (!ns)
> return ERR_PTR(-ENOMEM);
>
> + err = proc_alloc_inum(&ns->proc_inum);
> + if (err) {
> + kfree(ns);
> + return ERR_PTR(err);
> + }
> +
> down_read(&uts_sem);
> memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
> ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
> @@ -78,6 +85,7 @@ void free_uts_ns(struct kref *kref)
>
> ns = container_of(kref, struct uts_namespace, kref);
> put_user_ns(ns->user_ns);
> + proc_free_inum(ns->proc_inum);
> kfree(ns);
> }
>
> @@ -110,11 +118,18 @@ static int utsns_install(struct nsproxy *nsproxy, void *ns)
> return 0;
> }
>
> +static unsigned int utsns_inum(void *vp)
> +{
> + struct uts_namespace *ns = vp;
> +
> + return ns->proc_inum;
> +}
> +
> const struct proc_ns_operations utsns_operations = {
> .name = "uts",
> .type = CLONE_NEWUTS,
> .get = utsns_get,
> .put = utsns_put,
> .install = utsns_install,
> + .inum = utsns_inum,
> };
> -
> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> index e41e511..6199ec2 100644
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -358,6 +358,21 @@ struct net *get_net_ns_by_pid(pid_t pid)
> }
> EXPORT_SYMBOL_GPL(get_net_ns_by_pid);
>
> +static __net_init int net_ns_net_init(struct net *net)
> +{
> + return proc_alloc_inum(&net->proc_inum);
> +}
> +
> +static __net_exit void net_ns_net_exit(struct net *net)
> +{
> + proc_free_inum(net->proc_inum);
> +}
> +
> +static struct pernet_operations __net_initdata net_ns_ops = {
> + .init = net_ns_net_init,
> + .exit = net_ns_net_exit,
> +};
> +
> static int __init net_ns_init(void)
> {
> struct net_generic *ng;
> @@ -389,6 +404,8 @@ static int __init net_ns_init(void)
>
> mutex_unlock(&net_mutex);
>
> + register_pernet_subsys(&net_ns_ops);
> +
> return 0;
> }
>
> @@ -616,11 +633,18 @@ static int netns_install(struct nsproxy *nsproxy, void *ns)
> return 0;
> }
>
> +static unsigned int netns_inum(void *ns)
> +{
> + struct net *net = ns;
> + return net->proc_inum;
> +}
> +
> const struct proc_ns_operations netns_operations = {
> .name = "net",
> .type = CLONE_NEWNET,
> .get = netns_get,
> .put = netns_put,
> .install = netns_install,
> + .inum = netns_inum,
> };
> #endif
> --
> 1.7.5.1.217.g4e3aa
>
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