From 47a150edc2ae734c0f4bf50aa19499e23b9a46f8 Mon Sep 17 00:00:00 2001 From: "Serge E. Hallyn" Date: Fri, 13 May 2011 04:27:54 +0100 Subject: Cache user_ns in struct cred 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 [ 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 --- kernel/capability.c | 12 ++++++++++++ kernel/cred.c | 12 ++++++------ 2 files changed, 18 insertions(+), 6 deletions(-) (limited to 'kernel') diff --git a/kernel/capability.c b/kernel/capability.c index bf0c734d0c12..32a80e08ff4b 100644 --- a/kernel/capability.c +++ b/kernel/capability.c @@ -399,3 +399,15 @@ bool task_ns_capable(struct task_struct *t, int cap) return ns_capable(task_cred_xxx(t, user)->user_ns, cap); } EXPORT_SYMBOL(task_ns_capable); + +/** + * nsown_capable - Check superior capability to one's own user_ns + * @cap: The capability in question + * + * Return true if the current task has the given superior capability + * targeted at its own user namespace. + */ +bool nsown_capable(int cap) +{ + return ns_capable(current_user_ns(), cap); +} diff --git a/kernel/cred.c b/kernel/cred.c index 5557b55048df..8093c16b84b1 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -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) -- cgit v1.2.3