Commit 98f842e6 authored by Eric W. Biederman's avatar Eric W. Biederman

proc: Usable inode numbers for the namespace file descriptors.

Assign a unique proc inode to each namespace, and use that
inode number to ensure we only allocate at most one proc
inode for every namespace in proc.

A single proc inode per namespace allows userspace to test
to see if two processes are in the same 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 file descriptors)
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: default avatarEric W. Biederman <ebiederm@xmission.com>
parent bf056bfa
......@@ -4,6 +4,7 @@
struct mnt_namespace {
atomic_t count;
unsigned int proc_inum;
struct mount * root;
struct list_head list;
struct user_namespace *user_ns;
......
......@@ -2301,6 +2301,7 @@ dput_out:
static void free_mnt_ns(struct mnt_namespace *ns)
{
proc_free_inum(ns->proc_inum);
put_user_ns(ns->user_ns);
kfree(ns);
}
......@@ -2317,10 +2318,16 @@ static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1);
static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
{
struct mnt_namespace *new_ns;
int ret;
new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
if (!new_ns)
return ERR_PTR(-ENOMEM);
ret = proc_alloc_inum(&new_ns->proc_inum);
if (ret) {
kfree(new_ns);
return ERR_PTR(ret);
}
new_ns->seq = atomic64_add_return(1, &mnt_ns_seq);
atomic_set(&new_ns->count, 1);
new_ns->root = NULL;
......@@ -2799,10 +2806,17 @@ static int mntns_install(struct nsproxy *nsproxy, void *ns)
return 0;
}
static unsigned int mntns_inum(void *ns)
{
struct mnt_namespace *mnt_ns = ns;
return mnt_ns->proc_inum;
}
const struct proc_ns_operations mntns_operations = {
.name = "mnt",
.type = CLONE_NEWNS,
.get = mntns_get,
.put = mntns_put,
.install = mntns_install,
.inum = mntns_inum,
};
......@@ -82,7 +82,7 @@ static struct dentry *proc_ns_get_dentry(struct super_block *sb,
return ERR_PTR(-ENOMEM);
}
inode = new_inode(sb);
inode = iget_locked(sb, ns_ops->inum(ns));
if (!inode) {
dput(dentry);
ns_ops->put(ns);
......@@ -90,13 +90,17 @@ static struct dentry *proc_ns_get_dentry(struct super_block *sb,
}
ei = PROC_I(inode);
inode->i_ino = get_next_ino();
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
inode->i_op = &ns_inode_operations;
inode->i_mode = S_IFREG | S_IRUGO;
inode->i_fop = &ns_file_operations;
ei->ns_ops = ns_ops;
ei->ns = ns;
if (inode->i_state & I_NEW) {
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
inode->i_op = &ns_inode_operations;
inode->i_mode = S_IFREG | S_IRUGO;
inode->i_fop = &ns_file_operations;
ei->ns_ops = ns_ops;
ei->ns = ns;
unlock_new_inode(inode);
} else {
ns_ops->put(ns);
}
d_set_d_op(dentry, &ns_dentry_operations);
result = d_instantiate_unique(dentry, inode);
......@@ -162,12 +166,12 @@ static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int bufl
if (!ns)
goto out_put_task;
snprintf(name, sizeof(name), "%s", ns_ops->name);
snprintf(name, sizeof(name), "%s:[%u]", ns_ops->name, ns_ops->inum(ns));
len = strlen(name);
if (len > buflen)
len = buflen;
if (copy_to_user(buffer, ns_ops->name, len))
if (copy_to_user(buffer, name, len))
len = -EFAULT;
ns_ops->put(ns);
......
......@@ -67,6 +67,8 @@ 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;
......
......@@ -37,6 +37,7 @@ struct pid_namespace {
kgid_t pid_gid;
int hide_pid;
int reboot; /* group exit code if this pidns was rebooted */
unsigned int proc_inum;
};
extern struct pid_namespace init_pid_ns;
......
......@@ -28,7 +28,11 @@ struct mm_struct;
*/
enum {
PROC_ROOT_INO = 1,
PROC_ROOT_INO = 1,
PROC_IPC_INIT_INO = 0xEFFFFFFFU,
PROC_UTS_INIT_INO = 0xEFFFFFFEU,
PROC_USER_INIT_INO = 0xEFFFFFFDU,
PROC_PID_INIT_INO = 0xEFFFFFFCU,
};
/*
......@@ -263,6 +267,7 @@ 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;
......
......@@ -25,6 +25,7 @@ struct user_namespace {
struct user_namespace *parent;
kuid_t owner;
kgid_t group;
unsigned int proc_inum;
};
extern struct user_namespace init_user_ns;
......
......@@ -23,6 +23,7 @@ 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;
......
......@@ -56,6 +56,8 @@ struct net {
struct user_namespace *user_ns; /* Owning user namespace */
unsigned int proc_inum;
struct proc_dir_entry *proc_net;
struct proc_dir_entry *proc_net_stat;
......
......@@ -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);
......
......@@ -16,6 +16,7 @@
#include <linux/msg.h>
#include <linux/ipc_namespace.h>
#include <linux/utsname.h>
#include <linux/proc_fs.h>
#include <asm/uaccess.h>
#include "util.h"
......@@ -30,6 +31,7 @@ DEFINE_SPINLOCK(mq_lock);
struct ipc_namespace init_ipc_ns = {
.count = ATOMIC_INIT(1),
.user_ns = &init_user_ns,
.proc_inum = PROC_IPC_INIT_INO,
};
atomic_t nr_ipc_ns = ATOMIC_INIT(1);
......
......@@ -26,9 +26,16 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
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);
}
......@@ -111,6 +118,7 @@ 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);
}
......@@ -172,10 +180,18 @@ static int ipcns_install(struct nsproxy *nsproxy, void *new)
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,
};
......@@ -80,6 +80,7 @@ struct pid_namespace init_pid_ns = {
.level = 0,
.child_reaper = &init_task,
.user_ns = &init_user_ns,
.proc_inum = PROC_PID_INIT_INO,
};
EXPORT_SYMBOL_GPL(init_pid_ns);
......
......@@ -107,6 +107,10 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
if (ns->pid_cachep == NULL)
goto out_free_map;
err = proc_alloc_inum(&ns->proc_inum);
if (err)
goto out_free_map;
kref_init(&ns->kref);
ns->level = level;
ns->parent = get_pid_ns(parent_pid_ns);
......@@ -133,6 +137,7 @@ static void destroy_pid_namespace(struct pid_namespace *ns)
{
int i;
proc_free_inum(ns->proc_inum);
for (i = 0; i < PIDMAP_ENTRIES; i++)
kfree(ns->pidmap[i].page);
put_user_ns(ns->user_ns);
......@@ -345,12 +350,19 @@ static int pidns_install(struct nsproxy *nsproxy, void *ns)
return 0;
}
static unsigned int pidns_inum(void *ns)
{
struct pid_namespace *pid_ns = ns;
return pid_ns->proc_inum;
}
const struct proc_ns_operations pidns_operations = {
.name = "pid",
.type = CLONE_NEWPID,
.get = pidns_get,
.put = pidns_put,
.install = pidns_install,
.inum = pidns_inum,
};
static __init int pid_namespaces_init(void)
......
......@@ -16,6 +16,7 @@
#include <linux/interrupt.h>
#include <linux/export.h>
#include <linux/user_namespace.h>
#include <linux/proc_fs.h>
/*
* userns count is 1 for root user, 1 for init_uts_ns,
......@@ -51,6 +52,7 @@ struct user_namespace init_user_ns = {
},
.owner = GLOBAL_ROOT_UID,
.group = GLOBAL_ROOT_GID,
.proc_inum = PROC_USER_INIT_INO,
};
EXPORT_SYMBOL_GPL(init_user_ns);
......
......@@ -58,6 +58,7 @@ int create_user_ns(struct cred *new)
struct user_namespace *ns, *parent_ns = new->user_ns;
kuid_t owner = new->euid;
kgid_t group = new->egid;
int ret;
/* The creator needs a mapping in the parent user namespace
* or else we won't be able to reasonably tell userspace who
......@@ -71,6 +72,12 @@ int create_user_ns(struct cred *new)
if (!ns)
return -ENOMEM;
ret = proc_alloc_inum(&ns->proc_inum);
if (ret) {
kmem_cache_free(user_ns_cachep, ns);
return ret;
}
kref_init(&ns->kref);
/* Leave the new->user_ns reference with the new user namespace. */
ns->parent = parent_ns;
......@@ -103,6 +110,7 @@ void free_user_ns(struct kref *kref)
container_of(kref, struct user_namespace, kref);
parent = ns->parent;
proc_free_inum(ns->proc_inum);
kmem_cache_free(user_ns_cachep, ns);
put_user_ns(parent);
}
......@@ -808,12 +816,19 @@ static int userns_install(struct nsproxy *nsproxy, void *ns)
return commit_creds(cred);
}
static unsigned int userns_inum(void *ns)
{
struct user_namespace *user_ns = ns;
return user_ns->proc_inum;
}
const struct proc_ns_operations userns_operations = {
.name = "user",
.type = CLONE_NEWUSER,
.get = userns_get,
.put = userns_put,
.install = userns_install,
.inum = userns_inum,
};
static __init int user_namespaces_init(void)
......
......@@ -36,11 +36,18 @@ static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
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(user_ns);
......@@ -77,6 +84,7 @@ 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);
}
......@@ -114,11 +122,18 @@ static int utsns_install(struct nsproxy *nsproxy, void *new)
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,
};
......@@ -381,6 +381,21 @@ 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;
......@@ -412,6 +427,8 @@ static int __init net_ns_init(void)
mutex_unlock(&net_mutex);
register_pernet_subsys(&net_ns_ops);
return 0;
}
......@@ -640,11 +657,18 @@ 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
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