kernel-ark/include/linux/user_namespace.h
David Howells 5170836679 Fix recursive lock in free_uid()/free_user_ns()
free_uid() and free_user_ns() are corecursive when CONFIG_USER_SCHED=n,
but free_user_ns() is called from free_uid() by way of uid_hash_remove(),
which requires uidhash_lock to be held.  free_user_ns() then calls
free_uid() to complete the destruction.

Fix this by deferring the destruction of the user_namespace.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-02-27 16:26:21 -08:00

58 lines
1.1 KiB
C

#ifndef _LINUX_USER_NAMESPACE_H
#define _LINUX_USER_NAMESPACE_H
#include <linux/kref.h>
#include <linux/nsproxy.h>
#include <linux/sched.h>
#include <linux/err.h>
#define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 8)
#define UIDHASH_SZ (1 << UIDHASH_BITS)
struct user_namespace {
struct kref kref;
struct hlist_head uidhash_table[UIDHASH_SZ];
struct user_struct *creator;
struct work_struct destroyer;
};
extern struct user_namespace init_user_ns;
#ifdef CONFIG_USER_NS
static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
{
if (ns)
kref_get(&ns->kref);
return 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)
{
if (ns)
kref_put(&ns->kref, free_user_ns);
}
#else
static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
{
return &init_user_ns;
}
static inline int create_user_ns(struct cred *new)
{
return -EINVAL;
}
static inline void put_user_ns(struct user_namespace *ns)
{
}
#endif
#endif /* _LINUX_USER_H */