x86/vdso: Zap vvar pages when switching to a time namespace (70ddf651) · Commits · 戴 / test

arch/x86/entry/vdso/vma.c

+27 −0

Original line number	Diff line number	Diff line
		@@ -51,6 +51,7 @@ void __init init_vdso_image(const struct vdso_image *image)
		image->alt_len));
		}

		static const struct vm_special_mapping vvar_mapping;
		struct linux_binprm;

		static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
		@@ -128,6 +129,32 @@ static struct page find_timens_vvar_page(struct vm_area_struct vma)

		return NULL;
		}

		/*
		* The vvar page layout depends on whether a task belongs to the root or
		* non-root time namespace. Whenever a task changes its namespace, the VVAR
		* page tables are cleared and then they will re-faulted with a
		* corresponding layout.
		* See also the comment near timens_setup_vdso_data() for details.
		*/
		int vdso_join_timens(struct task_struct task, struct time_namespace ns)
		{
		struct mm_struct *mm = task->mm;
		struct vm_area_struct *vma;

		if (down_write_killable(&mm->mmap_sem))
		return -EINTR;

		for (vma = mm->mmap; vma; vma = vma->vm_next) {
		unsigned long size = vma->vm_end - vma->vm_start;

		if (vma_is_special_mapping(vma, &vvar_mapping))
		zap_page_range(vma, vma->vm_start, size);
		}

		up_write(&mm->mmap_sem);
		return 0;
		}
		#else
		static inline struct page find_timens_vvar_page(struct vm_area_struct vma)
		{

+9 −0

Original line number	Diff line number	Diff line
		@@ -31,6 +31,9 @@ struct time_namespace {
		extern struct time_namespace init_time_ns;

		#ifdef CONFIG_TIME_NS
		extern int vdso_join_timens(struct task_struct *task,
		struct time_namespace *ns);

		static inline struct time_namespace get_time_ns(struct time_namespace ns)
		{
		kref_get(&ns->kref);
		@@ -77,6 +80,12 @@ static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
		}

		#else
		static inline int vdso_join_timens(struct task_struct *task,
		struct time_namespace *ns)
		{
		return 0;
		}

		static inline struct time_namespace get_time_ns(struct time_namespace ns)
		{
		return NULL;

+10 −0

Original line number	Diff line number	Diff line
		@@ -281,6 +281,7 @@ static void timens_put(struct ns_common *ns)
		static int timens_install(struct nsproxy nsproxy, struct ns_common new)
		{
		struct time_namespace *ns = to_time_ns(new);
		int err;

		if (!current_is_single_threaded())
		return -EUSERS;
		@@ -291,6 +292,10 @@ static int timens_install(struct nsproxy nsproxy, struct ns_common new)

		timens_set_vvar_page(current, ns);

		err = vdso_join_timens(current, ns);
		if (err)
		return err;

		get_time_ns(ns);
		put_time_ns(nsproxy->time_ns);
		nsproxy->time_ns = ns;
		@@ -305,6 +310,7 @@ int timens_on_fork(struct nsproxy nsproxy, struct task_struct tsk)
		{
		struct ns_common *nsc = &nsproxy->time_ns_for_children->ns;
		struct time_namespace *ns = to_time_ns(nsc);
		int err;

		/* create_new_namespaces() already incremented the ref counter */
		if (nsproxy->time_ns == nsproxy->time_ns_for_children)
		@@ -312,6 +318,10 @@ int timens_on_fork(struct nsproxy nsproxy, struct task_struct tsk)

		timens_set_vvar_page(tsk, ns);

		err = vdso_join_timens(tsk, ns);
		if (err)
		return err;

		get_time_ns(ns);
		put_time_ns(nsproxy->time_ns);
		nsproxy->time_ns = ns;