From: Alexey Dobriyan <adobriyan@xxxxxxxxx> Subject: uts: create "struct uts_namespace" from kmem_cache 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. Link: http://lkml.kernel.org/r/20180228215158.GA23146@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Serge Hallyn <serge@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/utsname.h | 6 ++++++ init/main.c | 2 ++ kernel/utsname.c | 20 ++++++++++++++++---- 3 files changed, 24 insertions(+), 4 deletions(-) diff -puN include/linux/utsname.h~uts-create-struct-uts_namespace-from-kmem_cache include/linux/utsname.h --- a/include/linux/utsname.h~uts-create-struct-uts_namespace-from-kmem_cache +++ a/include/linux/utsname.h @@ -44,6 +44,8 @@ static inline void put_uts_ns(struct uts { 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 return old_ns; } + +static inline void uts_ns_init(void) +{ +} #endif #ifdef CONFIG_PROC_SYSCTL diff -puN init/main.c~uts-create-struct-uts_namespace-from-kmem_cache init/main.c --- a/init/main.c~uts-create-struct-uts_namespace-from-kmem_cache +++ a/init/main.c @@ -51,6 +51,7 @@ #include <linux/taskstats_kern.h> #include <linux/delayacct.h> #include <linux/unistd.h> +#include <linux/utsname.h> #include <linux/rmap.h> #include <linux/mempolicy.h> #include <linux/key.h> @@ -706,6 +707,7 @@ asmlinkage __visible void __init start_k cred_init(); fork_init(); proc_caches_init(); + uts_ns_init(); buffer_init(); key_init(); security_init(); diff -puN kernel/utsname.c~uts-create-struct-uts_namespace-from-kmem_cache kernel/utsname.c --- a/kernel/utsname.c~uts-create-struct-uts_namespace-from-kmem_cache +++ a/kernel/utsname.c @@ -19,6 +19,8 @@ #include <linux/proc_ns.h> #include <linux/sched/task.h> +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_ { 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_ /* * 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_n 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_op .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); +} _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
