[PATCH 2/2] proc: Usable inode numbers for the namespace file descriptors.
From: Eric W. Biederman
Date: Fri Jun 17 2011 - 19:33:31 EST
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>
---
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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