[PATCH review 07/16] userns: Make create_new_namespaces take a user_ns parameter

Eric W. Biederman
2012-11-19T15:14:20Z

Modify create_new_namespaces to explicitly take a user namespace
parameter, instead of implicitly through the task_struct.

This allows an implementation of unshare(CLONE_NEWUSER) where
the new user namespace is not stored onto the current task_struct
until after all of the namespaces are created.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
include/linux/ipc_namespace.h | 7 ++++---
include/linux/utsname.h | 6 +++---
ipc/namespace.c | 10 ++++------
kernel/nsproxy.c | 22 +++++++++++++---------
kernel/utsname.c | 9 ++++-----
5 files changed, 28 insertions(+), 26 deletions(-)

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index 5499c92..f03af70 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -133,7 +133,8 @@ static inline int mq_init_ns(struct ipc_namespace *ns) { return 0; }

#if defined(CONFIG_IPC_NS)
extern struct ipc_namespace *copy_ipcs(unsigned long flags,
- struct task_struct *tsk);
+ struct user_namespace *user_ns, struct ipc_namespace *ns);
+
static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
{
if (ns)
@@ -144,12 +145,12 @@ static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
extern void put_ipc_ns(struct ipc_namespace *ns);
#else
static inline struct ipc_namespace *copy_ipcs(unsigned long flags,
- struct task_struct *tsk)
+ struct user_namespace *user_ns, struct ipc_namespace *ns)
{
if (flags & CLONE_NEWIPC)
return ERR_PTR(-EINVAL);

- return tsk->nsproxy->ipc_ns;
+ return ns;
}

static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 2b34520..221f4a0 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -33,7 +33,7 @@ static inline void get_uts_ns(struct uts_namespace *ns)
}

extern struct uts_namespace *copy_utsname(unsigned long flags,
- struct task_struct *tsk);
+ struct user_namespace *user_ns, struct uts_namespace *old_ns);
extern void free_uts_ns(struct kref *kref);

static inline void put_uts_ns(struct uts_namespace *ns)
@@ -50,12 +50,12 @@ static inline void put_uts_ns(struct uts_namespace *ns)
}

static inline struct uts_namespace *copy_utsname(unsigned long flags,
- struct task_struct *tsk)
+ struct user_namespace *user_ns, struct uts_namespace *old_ns)
{
if (flags & CLONE_NEWUTS)
return ERR_PTR(-EINVAL);

- return tsk->nsproxy->uts_ns;
+ return old_ns;
}
#endif

diff --git a/ipc/namespace.c b/ipc/namespace.c
index 6ed33c0..72c8682 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -16,7 +16,7 @@

#include "util.h"

-static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk,
+static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
struct ipc_namespace *old_ns)
{
struct ipc_namespace *ns;
@@ -46,19 +46,17 @@ static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk,
ipcns_notify(IPCNS_CREATED);
register_ipcns_notifier(ns);

- ns->user_ns = get_user_ns(task_cred_xxx(tsk, user_ns));
+ ns->user_ns = get_user_ns(user_ns);

return ns;
}

struct ipc_namespace *copy_ipcs(unsigned long flags,
- struct task_struct *tsk)
+ struct user_namespace *user_ns, struct ipc_namespace *ns)
{
- struct ipc_namespace *ns = tsk->nsproxy->ipc_ns;
-
if (!(flags & CLONE_NEWIPC))
return get_ipc_ns(ns);
- return create_ipc_ns(tsk, ns);
+ return create_ipc_ns(user_ns, ns);
}

/*
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 4357a0a..2ddd816 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -57,7 +57,8 @@ static inline struct nsproxy *create_nsproxy(void)
* leave it to the caller to do proper locking and attach it to task.
*/
static struct nsproxy *create_new_namespaces(unsigned long flags,
- struct task_struct *tsk, struct fs_struct *new_fs)
+ struct task_struct *tsk, struct user_namespace *user_ns,
+ struct fs_struct *new_fs)
{
struct nsproxy *new_nsp;
int err;
@@ -66,31 +67,31 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
if (!new_nsp)
return ERR_PTR(-ENOMEM);

- new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, task_cred_xxx(tsk, user_ns), new_fs);
+ new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs);
if (IS_ERR(new_nsp->mnt_ns)) {
err = PTR_ERR(new_nsp->mnt_ns);
goto out_ns;
}

- new_nsp->uts_ns = copy_utsname(flags, tsk);
+ new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns);
if (IS_ERR(new_nsp->uts_ns)) {
err = PTR_ERR(new_nsp->uts_ns);
goto out_uts;
}

- new_nsp->ipc_ns = copy_ipcs(flags, tsk);
+ new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns);
if (IS_ERR(new_nsp->ipc_ns)) {
err = PTR_ERR(new_nsp->ipc_ns);
goto out_ipc;
}

- new_nsp->pid_ns = copy_pid_ns(flags, task_cred_xxx(tsk, user_ns), tsk->nsproxy->pid_ns);
+ new_nsp->pid_ns = copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns);
if (IS_ERR(new_nsp->pid_ns)) {
err = PTR_ERR(new_nsp->pid_ns);
goto out_pid;
}

- new_nsp->net_ns = copy_net_ns(flags, task_cred_xxx(tsk, user_ns), tsk->nsproxy->net_ns);
+ new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);
if (IS_ERR(new_nsp->net_ns)) {
err = PTR_ERR(new_nsp->net_ns);
goto out_net;
@@ -152,7 +153,8 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
goto out;
}

- new_ns = create_new_namespaces(flags, tsk, tsk->fs);
+ new_ns = create_new_namespaces(flags, tsk,
+ task_cred_xxx(tsk, user_ns), tsk->fs);
if (IS_ERR(new_ns)) {
err = PTR_ERR(new_ns);
goto out;
@@ -186,6 +188,7 @@ void free_nsproxy(struct nsproxy *ns)
int unshare_nsproxy_namespaces(unsigned long unshare_flags,
struct nsproxy **new_nsp, struct fs_struct *new_fs)
{
+ struct user_namespace *user_ns;
int err = 0;

if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
@@ -195,7 +198,8 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags,
if (!nsown_capable(CAP_SYS_ADMIN))
return -EPERM;

- *new_nsp = create_new_namespaces(unshare_flags, current,
+ user_ns = current_user_ns();
+ *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
new_fs ? new_fs : current->fs);
if (IS_ERR(*new_nsp)) {
err = PTR_ERR(*new_nsp);
@@ -252,7 +256,7 @@ SYSCALL_DEFINE2(setns, int, fd, int, nstype)
if (nstype && (ops->type != nstype))
goto out;

- new_nsproxy = create_new_namespaces(0, tsk, tsk->fs);
+ new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
if (IS_ERR(new_nsproxy)) {
err = PTR_ERR(new_nsproxy);
goto out;
diff --git a/kernel/utsname.c b/kernel/utsname.c
index 4a9362f..fdc619e 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -32,7 +32,7 @@ static struct uts_namespace *create_uts_ns(void)
* @old_ns: namespace to clone
* Return NULL on error (failure to kmalloc), new ns otherwise
*/
-static struct uts_namespace *clone_uts_ns(struct task_struct *tsk,
+static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
struct uts_namespace *old_ns)
{
struct uts_namespace *ns;
@@ -43,7 +43,7 @@ static struct uts_namespace *clone_uts_ns(struct task_struct *tsk,

down_read(&uts_sem);
memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
- ns->user_ns = get_user_ns(task_cred_xxx(tsk, user_ns));
+ ns->user_ns = get_user_ns(user_ns);
up_read(&uts_sem);
return ns;
}
@@ -55,9 +55,8 @@ static struct uts_namespace *clone_uts_ns(struct task_struct *tsk,
* versa.
*/
struct uts_namespace *copy_utsname(unsigned long flags,
- struct task_struct *tsk)
+ struct user_namespace *user_ns, struct uts_namespace *old_ns)
{
- struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
struct uts_namespace *new_ns;

BUG_ON(!old_ns);
@@ -66,7 +65,7 @@ struct uts_namespace *copy_utsname(unsigned long flags,
if (!(flags & CLONE_NEWUTS))
return old_ns;

- new_ns = clone_uts_ns(tsk, old_ns);
+ new_ns = clone_uts_ns(user_ns, old_ns);

put_uts_ns(old_ns);
return new_ns;
--
1.7.5.4