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SubjectRe: [PATCH] User namespaces: set of cleanups (eventually for linux-next?)
On Thu, 16 Oct 2008, Serge E. Hallyn wrote:

> Hi,
>
> Once the creds-next-subsys branch of the security testing tree hits
> linux-next, is there any chance of having this patch in there?

It should be in linux-next now.

> It
> offers (imho) drastic cleanup over the current userns code.
> LTP-approved (but then so were previous buggy versions...)
>
> David, since this consumes your patch, I wasn't sure whether it was
> appropriate to put your signed-off-by on here or not. I decided
> doing so was the worse of the potential offenses...
>
> thanks,
> -serge
>
> Subject: [PATCH] User namespaces: set of cleanups
> From: Serge Hallyn <serue@us.ibm.com>
> Date: 1224106725 -0500
>
> The user_ns is moved from nsproxy to user_struct, so that a struct
> cred by itself is sufficient to determine access (which it otherwise
> would not be). Corresponding ecryptfs fixes (by David Howells) are
> here as well.
>
> Fix refcounting. The following rules now apply:
> 1. The task pins the user struct.
> 2. The user struct pins its user namespace.
> 3. The user namespace pins the struct user which created it.
>
> User namespaces are cloned during copy_creds(). Unsharing a new user_ns
> is no longer possible. (We could re-add that, but it'll cause code
> duplication and doesn't seem useful if PAM doesn't need to clone user
> namespaces).
>
> When a user namespace is created, its first user (uid 0) gets empty
> keyrings and a clean group_info.
>
> Signed-off-by: Serge Hallyn <serue@us.ibm.com>
>
> ---
>
> fs/ecryptfs/messaging.c | 13 +++----
> fs/ecryptfs/miscdev.c | 19 ++++------
> include/linux/cred.h | 2 +
> include/linux/init_task.h | 1 -
> include/linux/nsproxy.h | 1 -
> include/linux/sched.h | 1 +
> include/linux/user_namespace.h | 13 ++-----
> kernel/cred.c | 15 +++++++-
> kernel/fork.c | 19 ++++++++--
> kernel/nsproxy.c | 15 +-------
> kernel/sys.c | 4 +-
> kernel/user.c | 47 +++++++-----------------
> kernel/user_namespace.c | 77 +++++++++++++++++-----------------------
> 13 files changed, 98 insertions(+), 129 deletions(-)
>
> 1d3aca5269bcd4471ca7725111d05ad92f17a3a5
> diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
> index 92bf606..eecb8b5 100644
> --- a/fs/ecryptfs/messaging.c
> +++ b/fs/ecryptfs/messaging.c
> @@ -376,7 +376,7 @@ int ecryptfs_process_response(struct ecr
> struct ecryptfs_msg_ctx *msg_ctx;
> size_t msg_size;
> struct nsproxy *nsproxy;
> - struct user_namespace *current_user_ns;
> + struct user_namespace *tsk_user_ns;
> uid_t ctx_euid;
> int rc;
>
> @@ -401,9 +401,9 @@ int ecryptfs_process_response(struct ecr
> mutex_unlock(&ecryptfs_daemon_hash_mux);
> goto wake_up;
> }
> - current_user_ns = nsproxy->user_ns;
> + tsk_user_ns = __task_cred(msg_ctx->task)->user->user_ns;
> ctx_euid = task_euid(msg_ctx->task);
> - rc = ecryptfs_find_daemon_by_euid(&daemon, ctx_euid, current_user_ns);
> + rc = ecryptfs_find_daemon_by_euid(&daemon, ctx_euid, tsk_user_ns);
> rcu_read_unlock();
> mutex_unlock(&ecryptfs_daemon_hash_mux);
> if (rc) {
> @@ -421,11 +421,11 @@ int ecryptfs_process_response(struct ecr
> euid, ctx_euid);
> goto unlock;
> }
> - if (current_user_ns != user_ns) {
> + if (tsk_user_ns != user_ns) {
> rc = -EBADMSG;
> printk(KERN_WARNING "%s: Received message from user_ns "
> "[0x%p]; expected message from user_ns [0x%p]\n",
> - __func__, user_ns, nsproxy->user_ns);
> + __func__, user_ns, tsk_user_ns);
> goto unlock;
> }
> if (daemon->pid != pid) {
> @@ -486,8 +486,7 @@ ecryptfs_send_message_locked(unsigned in
> uid_t euid = current_euid();
> int rc;
>
> - rc = ecryptfs_find_daemon_by_euid(&daemon, euid,
> - current->nsproxy->user_ns);
> + rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
> if (rc || !daemon) {
> rc = -ENOTCONN;
> printk(KERN_ERR "%s: User [%d] does not have a daemon "
> diff --git a/fs/ecryptfs/miscdev.c b/fs/ecryptfs/miscdev.c
> index 047ac60..efd95a0 100644
> --- a/fs/ecryptfs/miscdev.c
> +++ b/fs/ecryptfs/miscdev.c
> @@ -47,8 +47,7 @@ ecryptfs_miscdev_poll(struct file *file,
>
> mutex_lock(&ecryptfs_daemon_hash_mux);
> /* TODO: Just use file->private_data? */
> - rc = ecryptfs_find_daemon_by_euid(&daemon, euid,
> - current->nsproxy->user_ns);
> + rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
> BUG_ON(rc || !daemon);
> mutex_lock(&daemon->mux);
> mutex_unlock(&ecryptfs_daemon_hash_mux);
> @@ -95,11 +94,9 @@ ecryptfs_miscdev_open(struct inode *inod
> "count; rc = [%d]\n", __func__, rc);
> goto out_unlock_daemon_list;
> }
> - rc = ecryptfs_find_daemon_by_euid(&daemon, euid,
> - current->nsproxy->user_ns);
> + rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
> if (rc || !daemon) {
> - rc = ecryptfs_spawn_daemon(&daemon, euid,
> - current->nsproxy->user_ns,
> + rc = ecryptfs_spawn_daemon(&daemon, euid, current_user_ns(),
> task_pid(current));
> if (rc) {
> printk(KERN_ERR "%s: Error attempting to spawn daemon; "
> @@ -153,8 +150,7 @@ ecryptfs_miscdev_release(struct inode *i
> int rc;
>
> mutex_lock(&ecryptfs_daemon_hash_mux);
> - rc = ecryptfs_find_daemon_by_euid(&daemon, euid,
> - current->nsproxy->user_ns);
> + rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
> BUG_ON(rc || !daemon);
> mutex_lock(&daemon->mux);
> BUG_ON(daemon->pid != task_pid(current));
> @@ -254,8 +250,7 @@ ecryptfs_miscdev_read(struct file *file,
>
> mutex_lock(&ecryptfs_daemon_hash_mux);
> /* TODO: Just use file->private_data? */
> - rc = ecryptfs_find_daemon_by_euid(&daemon, euid,
> - current->nsproxy->user_ns);
> + rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
> BUG_ON(rc || !daemon);
> mutex_lock(&daemon->mux);
> if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
> @@ -295,7 +290,7 @@ check_list:
> goto check_list;
> }
> BUG_ON(euid != daemon->euid);
> - BUG_ON(current->nsproxy->user_ns != daemon->user_ns);
> + BUG_ON(current_user_ns() != daemon->user_ns);
> BUG_ON(task_pid(current) != daemon->pid);
> msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue,
> struct ecryptfs_msg_ctx, daemon_out_list);
> @@ -468,7 +463,7 @@ ecryptfs_miscdev_write(struct file *file
> goto out_free;
> }
> rc = ecryptfs_miscdev_response(&data[i], packet_size,
> - euid, current->nsproxy->user_ns,
> + euid, current_user_ns(),
> task_pid(current), seq);
> if (rc)
> printk(KERN_WARNING "%s: Failed to deliver miscdev "
> diff --git a/include/linux/cred.h b/include/linux/cred.h
> index 26c1ab1..3282ee4 100644
> --- a/include/linux/cred.h
> +++ b/include/linux/cred.h
> @@ -60,6 +60,7 @@ do { \
> } while (0)
>
> extern struct group_info *groups_alloc(int);
> +extern struct group_info init_groups;
> extern void groups_free(struct group_info *);
> extern int set_current_groups(struct group_info *);
> extern int set_groups(struct cred *, struct group_info *);
> @@ -315,6 +316,7 @@ static inline void put_cred(const struct
> #define current_fsgid() (current_cred_xxx(fsgid))
> #define current_cap() (current_cred_xxx(cap_effective))
> #define current_user() (current_cred_xxx(user))
> +#define current_user_ns() (current_cred_xxx(user)->user_ns)
> #define current_security() (current_cred_xxx(security))
>
> #define current_uid_gid(_uid, _gid) \
> diff --git a/include/linux/init_task.h b/include/linux/init_task.h
> index edf0285..126c3c4 100644
> --- a/include/linux/init_task.h
> +++ b/include/linux/init_task.h
> @@ -57,7 +57,6 @@ extern struct nsproxy init_nsproxy;
> .mnt_ns = NULL, \
> INIT_NET_NS(net_ns) \
> INIT_IPC_NS(ipc_ns) \
> - .user_ns = &init_user_ns, \
> }
>
> #define INIT_SIGHAND(sighand) { \
> diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
> index c8a768e..afad7de 100644
> --- a/include/linux/nsproxy.h
> +++ b/include/linux/nsproxy.h
> @@ -27,7 +27,6 @@ struct nsproxy {
> struct ipc_namespace *ipc_ns;
> struct mnt_namespace *mnt_ns;
> struct pid_namespace *pid_ns;
> - struct user_namespace *user_ns;
> struct net *net_ns;
> };
> extern struct nsproxy init_nsproxy;
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 0812cfd..02693db 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -595,6 +595,7 @@ struct user_struct {
> /* Hash table maintenance information */
> struct hlist_node uidhash_node;
> uid_t uid;
> + struct user_namespace *user_ns;
>
> #ifdef CONFIG_USER_SCHED
> struct task_group *tg;
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> index b5f41d4..315bcd3 100644
> --- a/include/linux/user_namespace.h
> +++ b/include/linux/user_namespace.h
> @@ -12,7 +12,7 @@
> struct user_namespace {
> struct kref kref;
> struct hlist_head uidhash_table[UIDHASH_SZ];
> - struct user_struct *root_user;
> + struct user_struct *creator;
> };
>
> extern struct user_namespace init_user_ns;
> @@ -26,8 +26,7 @@ static inline struct user_namespace *get
> return ns;
> }
>
> -extern struct user_namespace *copy_user_ns(int flags,
> - struct user_namespace *old_ns);
> +extern int create_user_ns(struct cred *new);
> extern void free_user_ns(struct kref *kref);
>
> static inline void put_user_ns(struct user_namespace *ns)
> @@ -43,13 +42,9 @@ static inline struct user_namespace *get
> return &init_user_ns;
> }
>
> -static inline struct user_namespace *copy_user_ns(int flags,
> - struct user_namespace *old_ns)
> +static inline int create_user_ns(struct cred *new)
> {
> - if (flags & CLONE_NEWUSER)
> - return ERR_PTR(-EINVAL);
> -
> - return old_ns;
> + return -EINVAL;
> }
>
> static inline void put_user_ns(struct user_namespace *ns)
> diff --git a/kernel/cred.c b/kernel/cred.c
> index 13697ca..ff7bc07 100644
> --- a/kernel/cred.c
> +++ b/kernel/cred.c
> @@ -274,6 +274,7 @@ int copy_creds(struct task_struct *p, un
> struct thread_group_cred *tgcred;
> #endif
> struct cred *new;
> + int ret;
>
> mutex_init(&p->cred_exec_mutex);
>
> @@ -293,6 +294,12 @@ int copy_creds(struct task_struct *p, un
> if (!new)
> return -ENOMEM;
>
> + if (clone_flags & CLONE_NEWUSER) {
> + ret = create_user_ns(new);
> + if (ret < 0)
> + goto error_put;
> + }
> +
> #ifdef CONFIG_KEYS
> /* new threads get their own thread keyrings if their parent already
> * had one */
> @@ -309,8 +316,8 @@ int copy_creds(struct task_struct *p, un
> if (!(clone_flags & CLONE_THREAD)) {
> tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
> if (!tgcred) {
> - put_cred(new);
> - return -ENOMEM;
> + ret = -ENOMEM;
> + goto error_put;
> }
> atomic_set(&tgcred->usage, 1);
> spin_lock_init(&tgcred->lock);
> @@ -325,6 +332,10 @@ int copy_creds(struct task_struct *p, un
> atomic_inc(&new->user->processes);
> p->cred = p->real_cred = get_cred(new);
> return 0;
> +
> +error_put:
> + put_cred(new);
> + return ret;
> }
>
> /**
> diff --git a/kernel/fork.c b/kernel/fork.c
> index e392e5a..c71f3c1 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -935,7 +935,7 @@ static struct task_struct *copy_process(
> if (atomic_read(&p->real_cred->user->processes) >=
> p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
> if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
> - p->real_cred->user != current->nsproxy->user_ns->root_user)
> + p->real_cred->user != INIT_USER)
> goto bad_fork_free;
> }
>
> @@ -1312,6 +1312,20 @@ long do_fork(unsigned long clone_flags,
> long nr;
>
> /*
> + * Do some preliminary argument and permissions checking before we
> + * actually start allocating stuff
> + */
> + if (clone_flags & CLONE_NEWUSER) {
> + if (clone_flags & CLONE_THREAD)
> + return -EINVAL;
> + /* hopefully this check will go away when userns support is
> + * complete
> + */
> + if (!capable(CAP_SYS_ADMIN))
> + return -EPERM;
> + }
> +
> + /*
> * We hope to recycle these flags after 2.6.26
> */
> if (unlikely(clone_flags & CLONE_STOPPED)) {
> @@ -1556,8 +1570,7 @@ asmlinkage long sys_unshare(unsigned lon
> err = -EINVAL;
> 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_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET))
> goto bad_unshare_out;
>
> /*
> diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
> index 1d3ef29..63598dc 100644
> --- a/kernel/nsproxy.c
> +++ b/kernel/nsproxy.c
> @@ -80,12 +80,6 @@ static struct nsproxy *create_new_namesp
> goto out_pid;
> }
>
> - new_nsp->user_ns = copy_user_ns(flags, tsk->nsproxy->user_ns);
> - if (IS_ERR(new_nsp->user_ns)) {
> - err = PTR_ERR(new_nsp->user_ns);
> - goto out_user;
> - }
> -
> new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns);
> if (IS_ERR(new_nsp->net_ns)) {
> err = PTR_ERR(new_nsp->net_ns);
> @@ -95,9 +89,6 @@ static struct nsproxy *create_new_namesp
> return new_nsp;
>
> out_net:
> - if (new_nsp->user_ns)
> - put_user_ns(new_nsp->user_ns);
> -out_user:
> if (new_nsp->pid_ns)
> put_pid_ns(new_nsp->pid_ns);
> out_pid:
> @@ -130,7 +121,7 @@ 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_NEWPID | CLONE_NEWNET)))
> return 0;
>
> if (!capable(CAP_SYS_ADMIN)) {
> @@ -173,8 +164,6 @@ void free_nsproxy(struct nsproxy *ns)
> put_ipc_ns(ns->ipc_ns);
> if (ns->pid_ns)
> put_pid_ns(ns->pid_ns);
> - if (ns->user_ns)
> - put_user_ns(ns->user_ns);
> put_net(ns->net_ns);
> kmem_cache_free(nsproxy_cachep, ns);
> }
> @@ -189,7 +178,7 @@ int unshare_nsproxy_namespaces(unsigned
> int err = 0;
>
> if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
> - CLONE_NEWUSER | CLONE_NEWNET)))
> + CLONE_NEWNET)))
> return 0;
>
> if (!capable(CAP_SYS_ADMIN))
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 6bc3899..26eda31 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -565,13 +565,13 @@ static int set_user(struct cred *new)
> {
> struct user_struct *new_user;
>
> - new_user = alloc_uid(current->nsproxy->user_ns, new->uid);
> + new_user = alloc_uid(current_user()->user_ns, new->uid);
> if (!new_user)
> return -EAGAIN;
>
> if (atomic_read(&new_user->processes) >=
> current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
> - new_user != current->nsproxy->user_ns->root_user) {
> + new_user != INIT_USER) {
> free_uid(new_user);
> return -EAGAIN;
> }
> diff --git a/kernel/user.c b/kernel/user.c
> index d476307..c0ef3a4 100644
> --- a/kernel/user.c
> +++ b/kernel/user.c
> @@ -20,9 +20,9 @@
>
> struct user_namespace init_user_ns = {
> .kref = {
> - .refcount = ATOMIC_INIT(2),
> + .refcount = ATOMIC_INIT(1),
> },
> - .root_user = &root_user,
> + .creator = &root_user,
> };
> EXPORT_SYMBOL_GPL(init_user_ns);
>
> @@ -48,12 +48,14 @@ static struct kmem_cache *uid_cachep;
> */
> static DEFINE_SPINLOCK(uidhash_lock);
>
> +/* root_user.__count is 2, 1 for init task cred, 1 for init_user_ns->creator */
> struct user_struct root_user = {
> - .__count = ATOMIC_INIT(1),
> + .__count = ATOMIC_INIT(2),
> .processes = ATOMIC_INIT(1),
> .files = ATOMIC_INIT(0),
> .sigpending = ATOMIC_INIT(0),
> .locked_shm = 0,
> + .user_ns = &init_user_ns,
> #ifdef CONFIG_USER_SCHED
> .tg = &init_task_group,
> #endif
> @@ -314,12 +316,13 @@ done:
> * IRQ state (as stored in flags) is restored and uidhash_lock released
> * upon function exit.
> */
> -static inline void free_user(struct user_struct *up, unsigned long flags)
> +static void free_user(struct user_struct *up, unsigned long flags)
> {
> /* restore back the count */
> atomic_inc(&up->__count);
> spin_unlock_irqrestore(&uidhash_lock, flags);
>
> + put_user_ns(up->user_ns);
> INIT_WORK(&up->work, remove_user_sysfs_dir);
> schedule_work(&up->work);
> }
> @@ -335,13 +338,14 @@ static inline void uids_mutex_unlock(voi
> * IRQ state (as stored in flags) is restored and uidhash_lock released
> * upon function exit.
> */
> -static inline void free_user(struct user_struct *up, unsigned long flags)
> +static void free_user(struct user_struct *up, unsigned long flags)
> {
> uid_hash_remove(up);
> spin_unlock_irqrestore(&uidhash_lock, flags);
> sched_destroy_user(up);
> key_put(up->uid_keyring);
> key_put(up->session_keyring);
> + put_user_ns(up->user_ns);
> kmem_cache_free(uid_cachep, up);
> }
>
> @@ -357,7 +361,7 @@ struct user_struct *find_user(uid_t uid)
> {
> struct user_struct *ret;
> unsigned long flags;
> - struct user_namespace *ns = current->nsproxy->user_ns;
> + struct user_namespace *ns = current_user()->user_ns;
>
> spin_lock_irqsave(&uidhash_lock, flags);
> ret = uid_hash_find(uid, uidhashentry(ns, uid));
> @@ -404,6 +408,8 @@ struct user_struct *alloc_uid(struct use
> if (sched_create_user(new) < 0)
> goto out_free_user;
>
> + new->user_ns = get_user_ns(ns);
> +
> if (uids_user_create(new))
> goto out_destoy_sched;
>
> @@ -427,7 +433,6 @@ struct user_struct *alloc_uid(struct use
> up = new;
> }
> spin_unlock_irq(&uidhash_lock);
> -
> }
>
> uids_mutex_unlock();
> @@ -436,6 +441,7 @@ struct user_struct *alloc_uid(struct use
>
> out_destoy_sched:
> sched_destroy_user(new);
> + put_user_ns(new->user_ns);
> out_free_user:
> kmem_cache_free(uid_cachep, new);
> out_unlock:
> @@ -443,33 +449,6 @@ out_unlock:
> return NULL;
> }
>
> -#ifdef CONFIG_USER_NS
> -void release_uids(struct user_namespace *ns)
> -{
> - int i;
> - unsigned long flags;
> - struct hlist_head *head;
> - struct hlist_node *nd;
> -
> - spin_lock_irqsave(&uidhash_lock, flags);
> - /*
> - * collapse the chains so that the user_struct-s will
> - * be still alive, but not in hashes. subsequent free_uid()
> - * will free them.
> - */
> - for (i = 0; i < UIDHASH_SZ; i++) {
> - head = ns->uidhash_table + i;
> - while (!hlist_empty(head)) {
> - nd = head->first;
> - hlist_del_init(nd);
> - }
> - }
> - spin_unlock_irqrestore(&uidhash_lock, flags);
> -
> - free_uid(ns->root_user);
> -}
> -#endif
> -
> static int __init uid_cache_init(void)
> {
> int n;
> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
> index 0d9c51d..53b164b 100644
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -9,70 +9,57 @@
> #include <linux/nsproxy.h>
> #include <linux/slab.h>
> #include <linux/user_namespace.h>
> +#include <linux/cred.h>
>
> /*
> - * Clone a new ns copying an original user ns, setting refcount to 1
> - * @old_ns: namespace to clone
> - * Return NULL on error (failure to kmalloc), new ns otherwise
> + * Create a new user namespace, deriving the creator from the user in the
> + * passed credentials, and replacing that user with the new root user for the
> + * new namespace.
> + *
> + * This is called by copy_creds(), which will finish setting the target task's
> + * credentials.
> */
> -static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
> +int create_user_ns(struct cred *new)
> {
> struct user_namespace *ns;
> - struct user_struct *new_user;
> - struct cred *new;
> + struct user_struct *root_user;
> int n;
>
> ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
> if (!ns)
> - return ERR_PTR(-ENOMEM);
> + return -ENOMEM;
>
> kref_init(&ns->kref);
>
> for (n = 0; n < UIDHASH_SZ; ++n)
> INIT_HLIST_HEAD(ns->uidhash_table + n);
>
> - /* Insert new root user. */
> - ns->root_user = alloc_uid(ns, 0);
> - if (!ns->root_user) {
> + /* Alloc new root user. */
> + root_user = alloc_uid(ns, 0);
> + if (!root_user) {
> kfree(ns);
> - return ERR_PTR(-ENOMEM);
> + return -ENOMEM;
> }
>
> - /* Reset current->user with a new one */
> - new_user = alloc_uid(ns, current_uid());
> - if (!new_user) {
> - free_uid(ns->root_user);
> - kfree(ns);
> - return ERR_PTR(-ENOMEM);
> - }
> -
> - /* Install the new user */
> - new = prepare_creds();
> - if (!new) {
> - free_uid(new_user);
> - free_uid(ns->root_user);
> - kfree(ns);
> - }
> - free_uid(new->user);
> - new->user = new_user;
> - commit_creds(new);
> - return ns;
> -}
> -
> -struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
> -{
> - struct user_namespace *new_ns;
> -
> - BUG_ON(!old_ns);
> - get_user_ns(old_ns);
> -
> - if (!(flags & CLONE_NEWUSER))
> - return old_ns;
> + /* set the new root user in the credentials under preparation */
> + ns->creator = new->user;
> + new->user = root_user;
> + new->uid = new->euid = new->suid = new->fsuid = 0;
> + new->gid = new->egid = new->sgid = new->fsgid = 0;
> + put_group_info(new->group_info);
> + new->group_info = get_group_info(&init_groups);
> + key_put(new->thread_keyring);
> +#ifdef CONFIG_KEYS
> + new->thread_keyring = NULL;
> + key_put(new->request_key_auth);
> + new->request_key_auth = NULL;
> +#endif
> + /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */
>
> - new_ns = clone_user_ns(old_ns);
> + /* alloc_uid() incremented the userns refcount. Just set it to 1 */
> + kref_set(&ns->kref, 1);
>
> - put_user_ns(old_ns);
> - return new_ns;
> + return 0;
> }
>
> void free_user_ns(struct kref *kref)
> @@ -80,7 +67,7 @@ void free_user_ns(struct kref *kref)
> struct user_namespace *ns;
>
> ns = container_of(kref, struct user_namespace, kref);
> - release_uids(ns);
> + free_uid(ns->creator);
> kfree(ns);
> }
> EXPORT_SYMBOL(free_user_ns);
> --
> 1.1.6
>

--
James Morris
<jmorris@namei.org>


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