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Date: Fri, 04 Apr 2008 10:54:22 -0700
From: Dave Leskovec <dlesko@...ux.vnet.ibm.com>
To: "Serge E. Hallyn" <serue@...ibm.com>
CC: lkml <linux-kernel@...r.kernel.org>,
Dhaval Giani <dhaval@...ux.vnet.ibm.com>,
Sukadev Bhattiprolu <sukadev@...ibm.com>
Subject: Re: [PATCH 1/1] user namespaces: add ns to user_struct (v3)
Hi Serge,
Yep, this latest patch fixed the user namespace problem I was seeing. Thanks!
Serge E. Hallyn wrote:
> Quoting Serge E. Hallyn (serue@...ibm.com):
>> Hi Dave,
>>
>> does the following patch against 2.6.25-rc8 fix the problem
>> with clone(CLONE_NEWUSER) failing when CONFIG_FAIR_USER_SCHED=y?
>
> The patch I sent didn't zero out the kobject before doing
> kbobject_init_and_add(), so that a kfree(kobj->name) during
> the registration causes an occasional oops. The following patch
> fixes that. Dave, please give it a shot and let me know.
>
> thanks,
> -serge
>
> From 40176b1cc0c1a9c24e8a0b572dce9ab60a8a99df Mon Sep 17 00:00:00 2001
> From: sergeh@...ibm.com <sergeh@...ibm.com>
> Date: Wed, 28 Nov 2007 14:50:54 -0800
> Subject: [PATCH 1/1] user namespaces: add ns to user_struct (v4)
>
> Add the user_namespace to user_struct.
>
> Move /sys/kernel/uids/<uid> under
> /sys/kernel/uids/<user_ns_address/<uid>
>
> Without this patch, FAIR_USER_SCHED breaks user namespaces.
> The -EEXIST for /sys/kernel/uids/<uid> causes the user
> namespace creation to fail.
>
> Changelog:
> apr 3: kzalloc user_ns to avoid kfree oops at kobject_init_and_add
> apr 2: update to 2.6.25-rc8
> feb 4: user hash tables are separate by namespace,
> so remove ns checks from uid_hash_find().
>
> Signed-off-by: Serge Hallyn <serue@...ibm.com>
> ---
> fs/dquot.c | 2 +-
> fs/ioprio.c | 2 +-
> include/linux/sched.h | 3 +-
> include/linux/types.h | 10 +++++++
> include/linux/user_namespace.h | 3 ++
> kernel/user.c | 56 +++++++++++++++++++++++++++++++++++++---
> kernel/user_namespace.c | 13 ++++++++-
> security/keys/process_keys.c | 8 +++---
> 8 files changed, 84 insertions(+), 13 deletions(-)
>
> diff --git a/fs/dquot.c b/fs/dquot.c
> index 41b9dbd..7414e5d 100644
> --- a/fs/dquot.c
> +++ b/fs/dquot.c
> @@ -960,7 +960,7 @@ static void send_warning(const struct dquot *dquot, const char warntype)
> MINOR(dquot->dq_sb->s_dev));
> if (ret)
> goto attr_err_out;
> - ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current->user->uid);
> + ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current->user->uid.uid);
> if (ret)
> goto attr_err_out;
> genlmsg_end(skb, msg_head);
> diff --git a/fs/ioprio.c b/fs/ioprio.c
> index c4a1c3c..139da15 100644
> --- a/fs/ioprio.c
> +++ b/fs/ioprio.c
> @@ -224,7 +224,7 @@ asmlinkage long sys_ioprio_get(int which, int who)
> break;
>
> do_each_thread(g, p) {
> - if (p->uid != user->uid)
> + if (!task_user_equiv(p, user))
> continue;
> tmpio = get_task_ioprio(p);
> if (tmpio < 0)
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 6a1e7af..1a25884 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -589,7 +589,7 @@ struct user_struct {
>
> /* Hash table maintenance information */
> struct hlist_node uidhash_node;
> - uid_t uid;
> + struct k_uid_t uid;
>
> #ifdef CONFIG_USER_SCHED
> struct task_group *tg;
> @@ -1654,6 +1654,7 @@ static inline struct user_struct *get_uid(struct user_struct *u)
> extern void free_uid(struct user_struct *);
> extern void switch_uid(struct user_struct *);
> extern void release_uids(struct user_namespace *ns);
> +extern int task_user_equiv(struct task_struct *tsk, struct user_struct *u);
>
> #include <asm/current.h>
>
> diff --git a/include/linux/types.h b/include/linux/types.h
> index 9dc2346..987e58d 100644
> --- a/include/linux/types.h
> +++ b/include/linux/types.h
> @@ -37,6 +37,16 @@ typedef __kernel_gid32_t gid_t;
> typedef __kernel_uid16_t uid16_t;
> typedef __kernel_gid16_t gid16_t;
>
> +struct k_uid_t {
> + uid_t uid;
> + struct user_namespace *ns;
> +};
> +
> +struct k_gid_t {
> + gid_t gid;
> + struct user_namespace *ns;
> +};
> +
> typedef unsigned long uintptr_t;
>
> #ifdef CONFIG_UID16
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> index b5f41d4..f0636d7 100644
> --- a/include/linux/user_namespace.h
> +++ b/include/linux/user_namespace.h
> @@ -12,10 +12,13 @@
> struct user_namespace {
> struct kref kref;
> struct hlist_head uidhash_table[UIDHASH_SZ];
> + struct kobject kobject;
> struct user_struct *root_user;
> };
>
> extern struct user_namespace init_user_ns;
> +extern int register_user_ns_kobj(struct user_namespace *ns);
> +extern void unregister_user_ns_kobj(struct user_namespace *ns);
>
> #ifdef CONFIG_USER_NS
>
> diff --git a/kernel/user.c b/kernel/user.c
> index 7132022..cd6bb89 100644
> --- a/kernel/user.c
> +++ b/kernel/user.c
> @@ -53,6 +53,10 @@ struct user_struct root_user = {
> .files = ATOMIC_INIT(0),
> .sigpending = ATOMIC_INIT(0),
> .locked_shm = 0,
> + .uid = {
> + .uid = 0,
> + .ns = &init_user_ns,
> + },
> #ifdef CONFIG_KEYS
> .uid_keyring = &root_user_keyring,
> .session_keyring = &root_session_keyring,
> @@ -75,13 +79,23 @@ static void uid_hash_remove(struct user_struct *up)
> hlist_del_init(&up->uidhash_node);
> }
>
> -static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
> +int task_user_equiv(struct task_struct *tsk, struct user_struct *u)
> +{
> + if (tsk->uid != u->uid.uid)
> + return 0;
> + if (tsk->nsproxy->user_ns != u->uid.ns)
> + return 0;
> + return 1;
> +}
> +
> +static struct user_struct *uid_hash_find(uid_t uid,
> + struct hlist_head *hashent)
> {
> struct user_struct *user;
> struct hlist_node *h;
>
> hlist_for_each_entry(user, h, hashent, uidhash_node) {
> - if (user->uid == uid) {
> + if (user->uid.uid == uid) {
> atomic_inc(&user->__count);
> return user;
> }
> @@ -226,7 +240,8 @@ static int uids_user_create(struct user_struct *up)
>
> memset(kobj, 0, sizeof(struct kobject));
> kobj->kset = uids_kset;
> - error = kobject_init_and_add(kobj, &uids_ktype, NULL, "%d", up->uid);
> + error = kobject_init_and_add(kobj, &uids_ktype, &up->uid.ns->kobject,
> + "%d", up->uid.uid);
> if (error) {
> kobject_put(kobj);
> goto done;
> @@ -244,10 +259,16 @@ done:
> */
> int __init uids_sysfs_init(void)
> {
> + int error;
> +
> uids_kset = kset_create_and_add("uids", NULL, kernel_kobj);
> if (!uids_kset)
> return -ENOMEM;
>
> + error = register_user_ns_kobj(&init_user_ns);
> + if (error)
> + return error;
> +
> return uids_user_create(&root_user);
> }
>
> @@ -305,6 +326,30 @@ static inline void free_user(struct user_struct *up, unsigned long flags)
> schedule_work(&up->work);
> }
>
> +int register_user_ns_kobj(struct user_namespace *ns)
> +{
> + struct kobject *obj = &ns->kobject;
> + int error;
> +
> + obj->kset = uids_kset;
> +
> + error = kobject_init_and_add(obj, &uids_ktype, &uids_kset->kobj,
> + "%lx", (unsigned long)ns);
> + if (error)
> + return error;
> +
> + kobject_uevent(obj, KOBJ_ADD);
> +
> + return 0;
> +}
> +
> +void unregister_user_ns_kobj(struct user_namespace *ns)
> +{
> + struct kobject *obj = &ns->kobject;
> + kobject_uevent(obj, KOBJ_REMOVE);
> + kobject_del(obj);
> +}
> +
> #else /* CONFIG_USER_SCHED && CONFIG_SYSFS */
>
> int uids_sysfs_init(void) { return 0; }
> @@ -326,6 +371,8 @@ static inline void free_user(struct user_struct *up, unsigned long flags)
> kmem_cache_free(uid_cachep, up);
> }
>
> +int register_user_ns_kobj(struct user_namespace *ns) { return 0; }
> +void unregister_user_ns_kobj(struct user_namespace *ns) {}
> #endif
>
> /*
> @@ -379,7 +426,8 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
> if (!new)
> goto out_unlock;
>
> - new->uid = uid;
> + new->uid.uid = uid;
> + new->uid.ns = ns;
> atomic_set(&new->__count, 1);
> atomic_set(&new->processes, 0);
> atomic_set(&new->files, 0);
> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
> index 4c90062..0ea3bf6 100644
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -19,12 +19,16 @@ static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
> {
> struct user_namespace *ns;
> struct user_struct *new_user;
> - int n;
> + int n, err;
>
> - ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
> + ns = kzalloc(sizeof(struct user_namespace), GFP_KERNEL);
> if (!ns)
> return ERR_PTR(-ENOMEM);
>
> + err = register_user_ns_kobj(ns);
> + if (err)
> + goto out_free_ns;
> +
> kref_init(&ns->kref);
>
> for (n = 0; n < UIDHASH_SZ; ++n)
> @@ -47,6 +51,10 @@ static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
>
> switch_uid(new_user);
> return ns;
> +
> +out_free_ns:
> + kfree(ns);
> + return ERR_PTR(err);
> }
>
> struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
> @@ -71,5 +79,6 @@ void free_user_ns(struct kref *kref)
>
> ns = container_of(kref, struct user_namespace, kref);
> release_uids(ns);
> + unregister_user_ns_kobj(ns);
> kfree(ns);
> }
> diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
> index c886a2b..0343a52 100644
> --- a/security/keys/process_keys.c
> +++ b/security/keys/process_keys.c
> @@ -75,9 +75,9 @@ int alloc_uid_keyring(struct user_struct *user,
> int ret;
>
> /* concoct a default session keyring */
> - sprintf(buf, "_uid_ses.%u", user->uid);
> + sprintf(buf, "_uid_ses.%u", user->uid.uid);
>
> - session_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx,
> + session_keyring = keyring_alloc(buf, user->uid.uid, (gid_t) -1, ctx,
> KEY_ALLOC_IN_QUOTA, NULL);
> if (IS_ERR(session_keyring)) {
> ret = PTR_ERR(session_keyring);
> @@ -86,9 +86,9 @@ int alloc_uid_keyring(struct user_struct *user,
>
> /* and a UID specific keyring, pointed to by the default session
> * keyring */
> - sprintf(buf, "_uid.%u", user->uid);
> + sprintf(buf, "_uid.%u", user->uid.uid);
>
> - uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx,
> + uid_keyring = keyring_alloc(buf, user->uid.uid, (gid_t) -1, ctx,
> KEY_ALLOC_IN_QUOTA, session_keyring);
> if (IS_ERR(uid_keyring)) {
> key_put(session_keyring);
--
Best Regards,
Dave Leskovec
IBM Linux Technology Center
Open Virtualization
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