From: Sukadev Bhattiprolu <[EMAIL PROTECTED]>
Subject: [RFC][PATCH 7/7]: Enable cloning PTY namespaces
Enable cloning PTY namespaces.
Note:
We are out of clone_flags! This patch depends on Cedric Le Goater's
clone64() patchset.
Changelog[v2]:
[Serge Hallyn]: Use rcu to access sb->s_fs_info.
Signed-off-by: Sukadev Bhattiprolu <[EMAIL PROTECTED]>
Signed-off-by: Serge Hallyn <[EMAIL PROTECTED]>
Signed-off-by: Matt Helsley <[EMAIL PROTECTED]>
---
fs/devpts/inode.c | 84 ++++++++++++++++++++++++++++++++++++++++++++--
include/linux/devpts_fs.h | 22 ++++++++++--
include/linux/init_task.h | 1
include/linux/nsproxy.h | 2 +
include/linux/sched.h | 1
kernel/fork.c | 2 -
kernel/nsproxy.c | 17 ++++++++-
7 files changed, 122 insertions(+), 7 deletions(-)
Index: 2.6.25-rc8-mm1/include/linux/sched.h
===================================================================
--- 2.6.25-rc8-mm1.orig/include/linux/sched.h 2008-04-08 13:38:08.000000000
-0700
+++ 2.6.25-rc8-mm1/include/linux/sched.h 2008-04-08 14:27:41.000000000
-0700
@@ -28,6 +28,7 @@
#define CLONE_NEWPID 0x20000000 /* New pid namespace */
#define CLONE_NEWNET 0x40000000 /* New network namespace */
#define CLONE_IO 0x80000000 /* Clone io context */
+#define CLONE_NEWPTS 0x0000000200000000ULL /* Clone pts ns */
/*
* Scheduling policies
Index: 2.6.25-rc8-mm1/include/linux/nsproxy.h
===================================================================
--- 2.6.25-rc8-mm1.orig/include/linux/nsproxy.h 2008-04-08 13:38:08.000000000
-0700
+++ 2.6.25-rc8-mm1/include/linux/nsproxy.h 2008-04-08 14:27:41.000000000
-0700
@@ -8,6 +8,7 @@ struct mnt_namespace;
struct uts_namespace;
struct ipc_namespace;
struct pid_namespace;
+struct pts_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 pts_namespace *pts_ns;
};
extern struct nsproxy init_nsproxy;
Index: 2.6.25-rc8-mm1/include/linux/init_task.h
===================================================================
--- 2.6.25-rc8-mm1.orig/include/linux/init_task.h 2008-04-08
13:38:08.000000000 -0700
+++ 2.6.25-rc8-mm1/include/linux/init_task.h 2008-04-08 14:27:41.000000000
-0700
@@ -78,6 +78,7 @@ extern struct nsproxy init_nsproxy;
.mnt_ns = NULL, \
INIT_NET_NS(net_ns) \
INIT_IPC_NS(ipc_ns) \
+ .pts_ns = &init_pts_ns, \
.user_ns = &init_user_ns, \
}
Index: 2.6.25-rc8-mm1/include/linux/devpts_fs.h
===================================================================
--- 2.6.25-rc8-mm1.orig/include/linux/devpts_fs.h 2008-04-08
13:38:08.000000000 -0700
+++ 2.6.25-rc8-mm1/include/linux/devpts_fs.h 2008-04-08 14:27:41.000000000
-0700
@@ -31,7 +31,7 @@ extern struct pts_namespace init_pts_ns;
static inline struct pts_namespace *current_pts_ns(void)
{
- return &init_pts_ns;
+ return current->nsproxy->pts_ns;
}
static inline struct pts_namespace *pts_ns_from_inode(struct inode *inode)
@@ -61,7 +61,8 @@ struct tty_struct *devpts_get_tty(struct
/* unlink */
void devpts_pty_kill(struct pts_namespace *pts_ns, int number);
-static inline void free_pts_ns(struct kref *ns_kref) { }
+extern struct pts_namespace *new_pts_ns(void);
+extern void free_pts_ns(struct kref *kref);
static inline struct pts_namespace *get_pts_ns(struct pts_namespace *ns)
{
@@ -75,6 +76,15 @@ static inline void put_pts_ns(struct pts
kref_put(&ns->kref, free_pts_ns);
}
+static inline struct pts_namespace *copy_pts_ns(u64 flags,
+ struct pts_namespace *old_ns)
+{
+ if (flags & CLONE_NEWPTS)
+ return new_pts_ns();
+ else
+ return get_pts_ns(old_ns);
+}
+
#else
/* Dummy stubs in the no-pty case */
@@ -90,6 +100,14 @@ static inline struct pts_namespace *get_
}
static inline void put_pts_ns(struct pts_namespace *ns) { }
+
+static inline struct pts_namespace *copy_pts_ns(u64 flags,
+ struct pts_namespace *old_ns)
+{
+ if (flags & CLONE_NEWPTS)
+ return ERR_PTR(-EINVAL);
+ return old_ns;
+}
#endif
Index: 2.6.25-rc8-mm1/fs/devpts/inode.c
===================================================================
--- 2.6.25-rc8-mm1.orig/fs/devpts/inode.c 2008-04-08 13:38:08.000000000
-0700
+++ 2.6.25-rc8-mm1/fs/devpts/inode.c 2008-04-08 14:33:04.000000000 -0700
@@ -27,6 +27,7 @@
extern int pty_limit; /* Config limit on Unix98 ptys */
static DECLARE_MUTEX(allocated_ptys_lock);
+static struct file_system_type devpts_fs_type;
static struct {
int setuid;
@@ -119,6 +120,57 @@ static const struct super_operations dev
.show_options = devpts_show_options,
};
+struct pts_namespace *new_pts_ns(void)
+{
+ struct pts_namespace *ns;
+
+ ns = kmalloc(sizeof(*ns), GFP_KERNEL);
+ if (!ns)
+ return ERR_PTR(-ENOMEM);
+
+ kref_init(&ns->kref);
+
+ ns->mnt = kern_mount_data(&devpts_fs_type, ns);
+ if (IS_ERR(ns->mnt)) {
+ kfree(ns);
+ return ERR_PTR(PTR_ERR(ns->mnt));
+ }
+
+ idr_init(&ns->allocated_ptys);
+
+ printk(KERN_NOTICE "Created pts-ns 0x%p\n", ns);
+
+ return ns;
+}
+
+void free_pts_ns(struct kref *ns_kref)
+{
+ struct pts_namespace *ns;
+
+ ns = container_of(ns_kref, struct pts_namespace, kref);
+
+ /*
+ * Clear s_fs_info here rather than in ->kill_sb(), since the pts_ns
+ * is invalid real soon now, but the ->kill_sb() will not happen
+ * until the last mntput(). And if some one is accessing this
+ * devpts mount from an ancestor pts ns, we may not be holding
+ * the last reference to this mnt.
+ *
+ * After clearing the pts_ns is NULL here, any acceses from parent
+ * will fail.
+ */
+ rcu_assign_pointer(ns->mnt->mnt_sb->s_fs_info, NULL);
+ mntput(ns->mnt);
+
+ /*
+ * TODO:
+ * idr_remove_all(&ns->allocated_ptys); introduced in 2.6.23
+ */
+ idr_destroy(&ns->allocated_ptys);
+ kfree(ns);
+
+ printk(KERN_NOTICE "Freed pts-ns 0x%p\n", ns);
+}
static int devpts_mknod(struct inode *dir, struct dentry *dentry,
int mode, dev_t rdev)
@@ -217,7 +269,16 @@ static int devpts_test_sb(struct super_b
static int devpts_set_sb(struct super_block *sb, void *data)
{
- sb->s_fs_info = data;
+ /*
+ * new_pts_ns() mounts the pts namespace and free_pts_ns()
+ * drops the reference to the mount. i.e the s_fs_info is
+ * cleared and vfsmnt is released _before_ pts_namespace
+ * is freed.
+ *
+ * So we don't need a reference to the pts_namespace here
+ * (Getting a reference here will also cause circular reference).
+ */
+ rcu_assign_pointer(sb->s_fs_info, data);
return set_anon_super(sb, NULL);
}
@@ -232,7 +293,7 @@ static int devpts_get_sb(struct file_sys
if (flags & MS_KERNMOUNT)
ns = data;
else
- ns = &init_pts_ns;
+ ns = current_pts_ns();
/* hereafter we're very simlar to get_sb_nodev */
sb = sget(fs_type, devpts_test_sb, devpts_set_sb, ns);
@@ -286,6 +347,13 @@ int devpts_new_index(struct pts_namespac
int index;
int idr_ret;
+ /*
+ * If pts_ns is NULL, this must be an access from an ancestor-pts-ns
+ * which happened just as this pts-ns was freed. Fail the access
+ * from parent-pts-ns.
+ */
+ if (!pts_ns)
+ return -EAGAIN;
retry:
if (!idr_pre_get(&pts_ns->allocated_ptys, GFP_KERNEL)) {
return -ENOMEM;
@@ -311,6 +379,7 @@ retry:
void devpts_kill_index(struct pts_namespace *pts_ns, int idx)
{
+ BUG_ON(pts_ns == NULL);
down(&allocated_ptys_lock);
idr_remove(&pts_ns->allocated_ptys, idx);
@@ -330,6 +399,7 @@ int devpts_pty_new( struct pts_namespace
/* We're supposed to be given the slave end of a pty */
BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
+ BUG_ON(pts_ns == NULL);
mnt = pts_ns->mnt;
root = mnt->mnt_root;
@@ -370,6 +440,14 @@ struct tty_struct *devpts_get_tty(struct
struct dentry *dentry;
struct tty_struct *tty;
+ /*
+ * If pts_ns is NULL, this must be an access from an ancestor-pts-ns
+ * which happened just as this pts-ns was freed. Fail the access
+ * from parent-pts-ns.
+ */
+ if (!pts_ns)
+ return ERR_PTR(-EAGAIN);
+
mnt = pts_ns->mnt;
dentry = get_node(mnt->mnt_root, number);
@@ -391,6 +469,8 @@ void devpts_pty_kill(struct pts_namespac
struct dentry *dentry;
struct dentry *root;
+ BUG_ON(pts_ns == NULL);
+
root = pts_ns->mnt->mnt_root;
dentry = get_node(root, number);
Index: 2.6.25-rc8-mm1/kernel/fork.c
===================================================================
--- 2.6.25-rc8-mm1.orig/kernel/fork.c 2008-04-08 13:38:08.000000000 -0700
+++ 2.6.25-rc8-mm1/kernel/fork.c 2008-04-08 14:27:41.000000000 -0700
@@ -1714,7 +1714,7 @@ static long do_unshare(u64 unshare_flags
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_NEWPTS))
goto bad_unshare_out;
if ((err = unshare_thread(unshare_flags)))
Index: 2.6.25-rc8-mm1/kernel/nsproxy.c
===================================================================
--- 2.6.25-rc8-mm1.orig/kernel/nsproxy.c 2008-04-08 13:38:08.000000000
-0700
+++ 2.6.25-rc8-mm1/kernel/nsproxy.c 2008-04-08 14:27:41.000000000 -0700
@@ -21,6 +21,7 @@
#include <linux/utsname.h>
#include <linux/pid_namespace.h>
#include <net/net_namespace.h>
+#include <linux/devpts_fs.h>
#include <linux/ipc_namespace.h>
static struct kmem_cache *nsproxy_cachep;
@@ -93,8 +94,17 @@ static struct nsproxy *create_new_namesp
goto out_net;
}
+ new_nsp->pts_ns = copy_pts_ns(flags, tsk->nsproxy->pts_ns);
+ if (IS_ERR(new_nsp->pts_ns)) {
+ err = PTR_ERR(new_nsp->pts_ns);
+ goto out_pts;
+ }
+
return new_nsp;
+out_pts:
+ if (new_nsp->net_ns)
+ put_net(new_nsp->net_ns);
out_net:
if (new_nsp->user_ns)
put_user_ns(new_nsp->user_ns);
@@ -131,7 +141,8 @@ int copy_namespaces(u64 flags, struct ta
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_NEWPTS)))
return 0;
if (!capable(CAP_SYS_ADMIN)) {
@@ -170,6 +181,8 @@ void free_nsproxy(struct nsproxy *ns)
put_pid_ns(ns->pid_ns);
if (ns->user_ns)
put_user_ns(ns->user_ns);
+ if (ns->pts_ns)
+ put_pts_ns(ns->pts_ns);
put_net(ns->net_ns);
kmem_cache_free(nsproxy_cachep, ns);
}
@@ -184,7 +197,7 @@ int unshare_nsproxy_namespaces(u64 unsha
int err = 0;
if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
- CLONE_NEWUSER | CLONE_NEWNET)))
+ CLONE_NEWUSER | CLONE_NEWNET | CLONE_NEWPTS)))
return 0;
if (!capable(CAP_SYS_ADMIN))
_______________________________________________
Containers mailing list
[EMAIL PROTECTED]
https://lists.linux-foundation.org/mailman/listinfo/containers
_______________________________________________
Devel mailing list
[email protected]
https://openvz.org/mailman/listinfo/devel
