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>
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@ -44,6 +44,8 @@ static inline void put_uts_ns(struct uts_namespace *ns)
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{
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kref_put(&ns->kref, free_uts_ns);
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}
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void uts_ns_init(void);
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#else
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static inline void get_uts_ns(struct uts_namespace *ns)
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{
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@ -61,6 +63,10 @@ static inline struct uts_namespace *copy_utsname(unsigned long flags,
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return old_ns;
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}
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static inline void uts_ns_init(void)
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{
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}
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#endif
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#ifdef CONFIG_PROC_SYSCTL
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@ -51,6 +51,7 @@
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#include <linux/taskstats_kern.h>
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#include <linux/delayacct.h>
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#include <linux/unistd.h>
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#include <linux/utsname.h>
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#include <linux/rmap.h>
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#include <linux/mempolicy.h>
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#include <linux/key.h>
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@ -706,6 +707,7 @@ asmlinkage __visible void __init start_kernel(void)
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cred_init();
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fork_init();
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proc_caches_init();
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uts_ns_init();
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buffer_init();
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key_init();
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security_init();
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@ -19,6 +19,8 @@
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#include <linux/proc_ns.h>
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#include <linux/sched/task.h>
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static struct kmem_cache *uts_ns_cache __ro_after_init;
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static struct ucounts *inc_uts_namespaces(struct user_namespace *ns)
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{
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return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES);
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@ -33,7 +35,7 @@ static struct uts_namespace *create_uts_ns(void)
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{
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struct uts_namespace *uts_ns;
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uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
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uts_ns = kmem_cache_alloc(uts_ns_cache, GFP_KERNEL);
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if (uts_ns)
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kref_init(&uts_ns->kref);
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return uts_ns;
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@ -42,7 +44,7 @@ static struct uts_namespace *create_uts_ns(void)
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/*
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* Clone a new ns copying an original utsname, setting refcount to 1
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* @old_ns: namespace to clone
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* Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise
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* Return ERR_PTR(-ENOMEM) on error (failure to allocate), new ns otherwise
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*/
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static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
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struct uts_namespace *old_ns)
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@ -75,7 +77,7 @@ static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
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return ns;
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fail_free:
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kfree(ns);
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kmem_cache_free(uts_ns_cache, ns);
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fail_dec:
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dec_uts_namespaces(ucounts);
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fail:
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@ -113,7 +115,7 @@ void free_uts_ns(struct kref *kref)
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dec_uts_namespaces(ns->ucounts);
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put_user_ns(ns->user_ns);
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ns_free_inum(&ns->ns);
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kfree(ns);
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kmem_cache_free(uts_ns_cache, ns);
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}
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static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
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@ -169,3 +171,13 @@ const struct proc_ns_operations utsns_operations = {
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.install = utsns_install,
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.owner = utsns_owner,
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};
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void __init uts_ns_init(void)
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{
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uts_ns_cache = kmem_cache_create_usercopy(
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"uts_namespace", sizeof(struct uts_namespace), 0,
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SLAB_PANIC|SLAB_ACCOUNT,
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offsetof(struct uts_namespace, name),
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sizeof_field(struct uts_namespace, name),
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NULL);
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}
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