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Cache user_ns in struct cred

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If !CONFIG_USERNS, have current_user_ns() defined to (&init_user_ns).

Get rid of _current_user_ns.  This requires nsown_capable() to be
defined in capability.c rather than as static inline in capability.h,
so do that.

Request_key needs init_user_ns defined at current_user_ns if
!CONFIG_USERNS, so forward-declare that in cred.h if !CONFIG_USERNS
at current_user_ns() define.

Compile-tested with and without CONFIG_USERNS.

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
[ This makes a huge performance difference for acl_permission_check(),
  up to 30%.  And that is one of the hottest kernel functions for loads
  that are pathname-lookup heavy.  ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Serge E. Hallyn
2011-05-13 04:27:54 +01:00
committed by Linus Torvalds
parent 381e7863d9
commit 47a150edc2
4 changed files with 27 additions and 20 deletions
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12
kernel/cred.c
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@@ -54,6 +54,7 @@ struct cred init_cred = {
.cap_effective = CAP_INIT_EFF_SET,
.cap_bset = CAP_INIT_BSET,
.user = INIT_USER,
.user_ns = &init_user_ns,
.group_info = &init_groups,
#ifdef CONFIG_KEYS
.tgcred = &init_tgcred,
@@ -410,6 +411,11 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
goto error_put;
}
/* cache user_ns in cred. Doesn't need a refcount because it will
* stay pinned by cred->user
*/
new->user_ns = new->user->user_ns;
#ifdef CONFIG_KEYS
/* new threads get their own thread keyrings if their parent already
* had one */
@@ -741,12 +747,6 @@ int set_create_files_as(struct cred *new, struct inode *inode)
}
EXPORT_SYMBOL(set_create_files_as);
struct user_namespace *current_user_ns(void)
{
return _current_user_ns();
}
EXPORT_SYMBOL(current_user_ns);
#ifdef CONFIG_DEBUG_CREDENTIALS
bool creds_are_invalid(const struct cred *cred)