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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@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alexey Dobriyan 2018-04-10 16:32:36 -07:00 committed by Linus Torvalds
parent bc4f2f5469
commit 3ea056c504
3 changed files with 24 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/utsname.h
View File

@ -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

2
init/main.c
View File

@ -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_kernel(void)
cred_init();
fork_init();
proc_caches_init();
uts_ns_init();
buffer_init();
key_init();
security_init();

20
kernel/utsname.c
View File

@ -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_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);
}