Messages in this thread Patch in this message | | | Date | Wed, 18 Mar 2009 02:34:18 +0300 | From | Alexey Dobriyan <> | Subject | struct user_namespace::creator |
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What is struct user_namespace::creator needed for?
The scheme when struct user pins struct user_namespace which frees ->creator which is supposed to pind user_ns is really icky.
I tried this (inclomplete) patch and nothing bad happened so far with CLONE_NEWUSER:
--- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -12,7 +12,6 @@ struct user_namespace { struct kref kref; struct hlist_head uidhash_table[UIDHASH_SZ]; - struct user_struct *creator; struct work_struct destroyer; }; diff --git a/kernel/user.c b/kernel/user.c index fbb300e..1cecb8c 100644 --- a/kernel/user.c +++ b/kernel/user.c @@ -22,7 +22,6 @@ struct user_namespace init_user_ns = { .kref = { .refcount = ATOMIC_INIT(1), }, - .creator = &root_user, }; EXPORT_SYMBOL_GPL(init_user_ns); @@ -48,9 +47,8 @@ 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(2), + .__count = ATOMIC_INIT(1), /* init_cred */ .processes = ATOMIC_INIT(1), .files = ATOMIC_INIT(0), .sigpending = ATOMIC_INIT(0), --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -12,10 +12,6 @@ #include <linux/cred.h> /* - * 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. */ @@ -42,7 +38,6 @@ int create_user_ns(struct cred *new) } /* 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; @@ -69,7 +64,6 @@ static void free_user_ns_work(struct work_struct *work) { struct user_namespace *ns = container_of(work, struct user_namespace, destroyer); - free_uid(ns->creator); kfree(ns); }
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