[RFC][PATCH 4/4]: Enable cloning PTY namespaces
sukadev at us.ibm.com
sukadev at us.ibm.com
Tue Feb 5 21:11:17 PST 2008
From: Sukadev Bhattiprolu <sukadev at us.ibm.com>
Subject: [RFC][PATCH 4/4]: Enable cloning PTY namespaces
Enable cloning PTY namespaces.
TODO:
This version temporarily uses the clone flag '0x80000000' which
is unused in mainline atm, but used for CLONE_IO in -mm.
While we must extend clone() (urgently) to solve this, it hopefully
does not affect review of the rest of this patchset.
Changelog:
- Version 0: Based on earlier versions from Serge Hallyn and
Matt Helsley.
Signed-off-by: Sukadev Bhattiprolu <sukadev at us.ibm.com>
---
fs/devpts/inode.c | 84 +++++++++++++++++++++++++++++++++++++++-------
include/linux/devpts_fs.h | 52 ++++++++++++++++++++++++++++
include/linux/init_task.h | 1
include/linux/nsproxy.h | 2 +
include/linux/sched.h | 2 +
kernel/fork.c | 2 -
kernel/nsproxy.c | 17 ++++++++-
7 files changed, 146 insertions(+), 14 deletions(-)
Index: linux-2.6.24/fs/devpts/inode.c
===================================================================
--- linux-2.6.24.orig/fs/devpts/inode.c 2008-02-05 19:16:39.000000000 -0800
+++ linux-2.6.24/fs/devpts/inode.c 2008-02-05 20:27:41.000000000 -0800
@@ -25,18 +25,25 @@
#define DEVPTS_SUPER_MAGIC 0x1cd1
extern int pty_limit; /* Config limit on Unix98 ptys */
-static DEFINE_IDR(allocated_ptys);
static DECLARE_MUTEX(allocated_ptys_lock);
+static struct file_system_type devpts_fs_type;
+
+struct pts_namespace init_pts_ns = {
+ .kref = {
+ .refcount = ATOMIC_INIT(2),
+ },
+ .allocated_ptys = IDR_INIT(init_pts_ns.allocated_ptys),
+ .mnt = NULL,
+};
static inline struct idr *current_pts_ns_allocated_ptys(void)
{
- return &allocated_ptys;
+ return ¤t->nsproxy->pts_ns->allocated_ptys;
}
-static struct vfsmount *devpts_mnt;
static inline struct vfsmount *current_pts_ns_mnt(void)
{
- return devpts_mnt;
+ return current->nsproxy->pts_ns->mnt;
}
static struct {
@@ -59,6 +66,42 @@ static match_table_t tokens = {
{Opt_err, NULL}
};
+struct pts_namespace *new_pts_ns(void)
+{
+ struct pts_namespace *ns;
+
+ ns = kmalloc(sizeof(*ns), GFP_KERNEL);
+ if (!ns)
+ return ERR_PTR(-ENOMEM);
+
+ 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);
+ kref_init(&ns->kref);
+
+ return ns;
+}
+
+void free_pts_ns(struct kref *ns_kref)
+{
+ struct pts_namespace *ns;
+
+ ns = container_of(ns_kref, struct pts_namespace, kref);
+ BUG_ON(ns == &init_pts_ns);
+
+ mntput(ns->mnt);
+ /*
+ * TODO:
+ * idr_remove_all(&ns->allocated_ptys); introduced in 2.6.23
+ */
+ idr_destroy(&ns->allocated_ptys);
+ kfree(ns);
+}
+
static int devpts_remount(struct super_block *sb, int *flags, char *data)
{
char *p;
@@ -160,18 +203,27 @@ static int devpts_test_sb(struct super_b
static int devpts_set_sb(struct super_block *sb, void *data)
{
- sb->s_fs_info = data;
+ struct pts_namespace *ns = data;
+
+ sb->s_fs_info = get_pts_ns(ns);
return set_anon_super(sb, NULL);
}
static int devpts_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
+ struct pts_namespace *ns;
struct super_block *sb;
int err;
+ /* hereafter we're very similar to proc_get_sb */
+ if (flags & MS_KERNMOUNT)
+ ns = data;
+ else
+ ns = current->nsproxy->pts_ns;
+
/* hereafter we're very simlar to get_sb_nodev */
- sb = sget(fs_type, devpts_test_sb, devpts_set_sb, data);
+ sb = sget(fs_type, devpts_test_sb, devpts_set_sb, ns);
if (IS_ERR(sb))
return PTR_ERR(sb);
@@ -187,16 +239,25 @@ static int devpts_get_sb(struct file_sys
}
sb->s_flags |= MS_ACTIVE;
- devpts_mnt = mnt;
+ ns->mnt = mnt;
return simple_set_mnt(mnt, sb);
}
+static void devpts_kill_sb(struct super_block *sb)
+{
+ struct pts_namespace *ns;
+
+ ns = sb->s_fs_info;
+ kill_anon_super(sb);
+ put_pts_ns(ns);
+}
+
static struct file_system_type devpts_fs_type = {
.owner = THIS_MODULE,
.name = "devpts",
.get_sb = devpts_get_sb,
- .kill_sb = kill_anon_super,
+ .kill_sb = devpts_kill_sb,
};
/*
@@ -352,18 +413,19 @@ static int __init init_devpts_fs(void)
if (err)
return err;
- mnt = kern_mount_data(&devpts_fs_type, NULL);
+ mnt = kern_mount_data(&devpts_fs_type, &init_pts_ns);
if (IS_ERR(mnt))
err = PTR_ERR(mnt);
else
- devpts_mnt = mnt;
+ init_pts_ns.mnt = mnt;
return err;
}
static void __exit exit_devpts_fs(void)
{
unregister_filesystem(&devpts_fs_type);
- mntput(devpts_mnt);
+ mntput(init_pts_ns.mnt);
+ init_pts_ns.mnt = NULL;
}
module_init(init_devpts_fs)
Index: linux-2.6.24/include/linux/devpts_fs.h
===================================================================
--- linux-2.6.24.orig/include/linux/devpts_fs.h 2008-02-05 19:16:39.000000000 -0800
+++ linux-2.6.24/include/linux/devpts_fs.h 2008-02-05 20:21:08.000000000 -0800
@@ -14,9 +14,45 @@
#define _LINUX_DEVPTS_FS_H
#include <linux/errno.h>
+#include <linux/nsproxy.h>
+#include <linux/kref.h>
+#include <linux/idr.h>
+
+struct pts_namespace {
+ struct kref kref;
+ struct idr allocated_ptys;
+ struct vfsmount *mnt;
+};
+
+extern struct pts_namespace init_pts_ns;
#ifdef CONFIG_UNIX98_PTYS
+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)
+{
+ if (ns)
+ kref_get(&ns->kref);
+ return ns;
+}
+
+static inline void put_pts_ns(struct pts_namespace *ns)
+{
+ if (ns)
+ kref_put(&ns->kref, free_pts_ns);
+}
+
+static inline struct pts_namespace *copy_pts_ns(unsigned long flags,
+ struct pts_namespace *old_ns)
+{
+ if (flags & CLONE_NEWPTS)
+ return new_pts_ns();
+ else
+ return get_pts_ns(old_ns);
+}
+
int devpts_new_index(void);
void devpts_kill_index(int idx);
int devpts_pty_new(struct tty_struct *tty); /* mknod in devpts */
@@ -26,6 +62,22 @@ void devpts_pty_kill(int number); /* u
#else
/* Dummy stubs in the no-pty case */
+
+static inline struct pts_namespace *get_pts_ns(struct pts_namespace *ns)
+{
+ return &init_pts_ns;
+}
+
+static inline void put_pts_ns(struct pts_namespace *ns) { }
+
+static inline struct pts_namespace *copy_pts_ns(unsigned long flags,
+ struct pts_namespace *old_ns)
+{
+ if (flags & CLONE_NEWPTS)
+ return ERR_PTR(-EINVAL);
+ return old_ns;
+}
+
static inline int devpts_new_index(void) { return -EINVAL; }
static inline void devpts_kill_index(int idx) { }
static inline int devpts_pty_new(struct tty_struct *tty) { return -EINVAL; }
Index: linux-2.6.24/include/linux/init_task.h
===================================================================
--- linux-2.6.24.orig/include/linux/init_task.h 2008-02-05 19:16:39.000000000 -0800
+++ linux-2.6.24/include/linux/init_task.h 2008-02-05 19:18:00.000000000 -0800
@@ -77,6 +77,7 @@ 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: linux-2.6.24/include/linux/nsproxy.h
===================================================================
--- linux-2.6.24.orig/include/linux/nsproxy.h 2008-02-05 19:16:39.000000000 -0800
+++ linux-2.6.24/include/linux/nsproxy.h 2008-02-05 19:18:00.000000000 -0800
@@ -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: linux-2.6.24/include/linux/sched.h
===================================================================
--- linux-2.6.24.orig/include/linux/sched.h 2008-02-05 19:16:39.000000000 -0800
+++ linux-2.6.24/include/linux/sched.h 2008-02-05 19:54:05.000000000 -0800
@@ -27,6 +27,8 @@
#define CLONE_NEWUSER 0x10000000 /* New user namespace */
#define CLONE_NEWPID 0x20000000 /* New pid namespace */
#define CLONE_NEWNET 0x40000000 /* New network namespace */
+#define CLONE_NEWPTS (CLONE_NEWNS|0x80000000) /* Temporary - only for patch review */
+ /* Badly need to /extend clone() !!! */
/*
* Scheduling policies
Index: linux-2.6.24/kernel/fork.c
===================================================================
--- linux-2.6.24.orig/kernel/fork.c 2008-02-05 19:16:39.000000000 -0800
+++ linux-2.6.24/kernel/fork.c 2008-02-05 19:18:00.000000000 -0800
@@ -1655,7 +1655,7 @@ 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_NEWPTS))
goto bad_unshare_out;
if ((err = unshare_thread(unshare_flags)))
Index: linux-2.6.24/kernel/nsproxy.c
===================================================================
--- linux-2.6.24.orig/kernel/nsproxy.c 2008-02-05 19:16:39.000000000 -0800
+++ linux-2.6.24/kernel/nsproxy.c 2008-02-05 19:18:00.000000000 -0800
@@ -21,6 +21,7 @@
#include <linux/utsname.h>
#include <linux/pid_namespace.h>
#include <net/net_namespace.h>
+#include <linux/devpts_fs.h>
static struct kmem_cache *nsproxy_cachep;
@@ -92,8 +93,17 @@ 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);
@@ -130,7 +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_NEWPTS)))
return 0;
if (!capable(CAP_SYS_ADMIN)) {
@@ -169,6 +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->pts_ns)
+ put_pts_ns(ns->pts_ns);
put_net(ns->net_ns);
kmem_cache_free(nsproxy_cachep, ns);
}
@@ -183,7 +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_NEWPTS)))
return 0;
if (!capable(CAP_SYS_ADMIN))
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