From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935215AbeB1VwD (ORCPT ); Wed, 28 Feb 2018 16:52:03 -0500 Received: from mail-wr0-f194.google.com ([209.85.128.194]:37267 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935042AbeB1VwC (ORCPT ); Wed, 28 Feb 2018 16:52:02 -0500 X-Google-Smtp-Source: AH8x224uuuXde2k9CMdKbgyGZzYPYuuDF8cir92WlHZ/U7RmuDuf+kVNQZMYeqUunhXbZbR9gGY6Ug== Date: Thu, 1 Mar 2018 00:51:58 +0300 From: Alexey Dobriyan To: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH] uts: create "struct uts_namespace" from kmem_cache Message-ID: <20180228215158.GA23146@avx2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org So "struct uts_namespace" can enjoy fine-grained SLAB debugging and usercopy protection. I'd prefer shorter name "utsns" but there is "user_namespace" already. Signed-off-by: Alexey Dobriyan --- include/linux/utsname.h | 6 ++++++ init/main.c | 2 ++ kernel/utsname.c | 20 ++++++++++++++++---- 3 files changed, 24 insertions(+), 4 deletions(-) --- a/include/linux/utsname.h +++ b/include/linux/utsname.h @@ -44,6 +44,8 @@ static inline void put_uts_ns(struct uts_namespace *ns) { kref_put(&ns->kref, free_uts_ns); } + +void uts_ns_init(void); #else static inline void get_uts_ns(struct uts_namespace *ns) { @@ -61,6 +63,10 @@ static inline struct uts_namespace *copy_utsname(unsigned long flags, return old_ns; } + +static inline void uts_ns_init(void) +{ +} #endif #ifdef CONFIG_PROC_SYSCTL --- a/init/main.c +++ b/init/main.c @@ -51,6 +51,7 @@ #include #include #include +#include #include #include #include @@ -689,6 +690,7 @@ asmlinkage __visible void __init start_kernel(void) cred_init(); fork_init(); proc_caches_init(); + uts_ns_init(); buffer_init(); key_init(); security_init(); --- a/kernel/utsname.c +++ b/kernel/utsname.c @@ -19,6 +19,8 @@ #include #include +static struct kmem_cache *uts_ns_cache __ro_after_init; + static struct ucounts *inc_uts_namespaces(struct user_namespace *ns) { return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES); @@ -33,7 +35,7 @@ static struct uts_namespace *create_uts_ns(void) { struct uts_namespace *uts_ns; - uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL); + uts_ns = kmem_cache_alloc(uts_ns_cache, GFP_KERNEL); if (uts_ns) kref_init(&uts_ns->kref); return uts_ns; @@ -42,7 +44,7 @@ static struct uts_namespace *create_uts_ns(void) /* * Clone a new ns copying an original utsname, setting refcount to 1 * @old_ns: namespace to clone - * Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise + * Return ERR_PTR(-ENOMEM) on error (failure to allocate), new ns otherwise */ static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns, struct uts_namespace *old_ns) @@ -75,7 +77,7 @@ static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns, return ns; fail_free: - kfree(ns); + kmem_cache_free(uts_ns_cache, ns); fail_dec: dec_uts_namespaces(ucounts); fail: @@ -113,7 +115,7 @@ void free_uts_ns(struct kref *kref) dec_uts_namespaces(ns->ucounts); put_user_ns(ns->user_ns); ns_free_inum(&ns->ns); - kfree(ns); + kmem_cache_free(uts_ns_cache, ns); } static inline struct uts_namespace *to_uts_ns(struct ns_common *ns) @@ -169,3 +171,13 @@ const struct proc_ns_operations utsns_operations = { .install = utsns_install, .owner = utsns_owner, }; + +void __init uts_ns_init(void) +{ + uts_ns_cache = kmem_cache_create_usercopy( + "uts_namespace", sizeof(struct uts_namespace), 0, + SLAB_PANIC|SLAB_ACCOUNT, + offsetof(struct uts_namespace, name), + sizeof_field(struct uts_namespace, name), + NULL); +}