Commit d6c494e8 authored by Jann Horn's avatar Jann Horn Committed by Thomas Gleixner
Browse files

vdso/timens: Refactor copy-pasted find_timens_vvar_page() helper into one copy 



find_timens_vvar_page() is not architecture-specific, as can be seen from
how all five per-architecture versions of it are the same.

(arm64, powerpc and riscv are exactly the same; x86 and s390 have two
characters difference inside a comment, less blank lines, and mark the
!CONFIG_TIME_NS version as inline.)

Refactor the five copies into a central copy in kernel/time/namespace.c.

Signed-off-by: default avatarJann Horn <jannh@google.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20221130115320.2918447-1-jannh@google.com
parent e0d3da98

arch/arm64/kernel/vdso.c

+0 −22
Original line number Diff line number Diff line
@@ -151,28 +151,6 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) 
	mmap_read_unlock(mm);

	return 0;

}



static struct page *find_timens_vvar_page(struct vm_area_struct *vma)

{

	if (likely(vma->vm_mm == current->mm))

		return current->nsproxy->time_ns->vvar_page;



	/*

	 * VM_PFNMAP | VM_IO protect .fault() handler from being called

	 * through interfaces like /proc/$pid/mem or

	 * process_vm_{readv,writev}() as long as there's no .access()

	 * in special_mapping_vmops.

	 * For more details check_vma_flags() and __access_remote_vm()

	 */

	WARN(1, "vvar_page accessed remotely");



	return NULL;

}

#else

static struct page *find_timens_vvar_page(struct vm_area_struct *vma)

{

	return NULL;

}

#endif



static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,

arch/powerpc/kernel/vdso.c

+0 −22
Original line number Diff line number Diff line
@@ -129,28 +129,6 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) 


	return 0;

}



static struct page *find_timens_vvar_page(struct vm_area_struct *vma)

{

	if (likely(vma->vm_mm == current->mm))

		return current->nsproxy->time_ns->vvar_page;



	/*

	 * VM_PFNMAP | VM_IO protect .fault() handler from being called

	 * through interfaces like /proc/$pid/mem or

	 * process_vm_{readv,writev}() as long as there's no .access()

	 * in special_mapping_vmops.

	 * For more details check_vma_flags() and __access_remote_vm()

	 */

	WARN(1, "vvar_page accessed remotely");



	return NULL;

}

#else

static struct page *find_timens_vvar_page(struct vm_area_struct *vma)

{

	return NULL;

}

#endif



static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,

arch/riscv/kernel/vdso.c

+0 −22
Original line number Diff line number Diff line
@@ -137,28 +137,6 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) 
	mmap_read_unlock(mm);

	return 0;

}



static struct page *find_timens_vvar_page(struct vm_area_struct *vma)

{

	if (likely(vma->vm_mm == current->mm))

		return current->nsproxy->time_ns->vvar_page;



	/*

	 * VM_PFNMAP | VM_IO protect .fault() handler from being called

	 * through interfaces like /proc/$pid/mem or

	 * process_vm_{readv,writev}() as long as there's no .access()

	 * in special_mapping_vmops.

	 * For more details check_vma_flags() and __access_remote_vm()

	 */

	WARN(1, "vvar_page accessed remotely");



	return NULL;

}

#else

static struct page *find_timens_vvar_page(struct vm_area_struct *vma)

{

	return NULL;

}

#endif



static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,

arch/s390/kernel/vdso.c

+0 −20
Original line number Diff line number Diff line
@@ -44,21 +44,6 @@ struct vdso_data *arch_get_vdso_data(void *vvar_page) 
	return (struct vdso_data *)(vvar_page);

}



static struct page *find_timens_vvar_page(struct vm_area_struct *vma)

{

	if (likely(vma->vm_mm == current->mm))

		return current->nsproxy->time_ns->vvar_page;

	/*

	 * VM_PFNMAP | VM_IO protect .fault() handler from being called

	 * through interfaces like /proc/$pid/mem or

	 * process_vm_{readv,writev}() as long as there's no .access()

	 * in special_mapping_vmops().

	 * For more details check_vma_flags() and __access_remote_vm()

	 */

	WARN(1, "vvar_page accessed remotely");

	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
@@ -84,11 +69,6 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) 
	mmap_read_unlock(mm);

	return 0;

}

#else

static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)

{

	return NULL;

}

#endif



static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,

arch/x86/entry/vdso/vma.c

+0 −23
Original line number Diff line number Diff line
@@ -98,24 +98,6 @@ static int vdso_mremap(const struct vm_special_mapping *sm, 
}



#ifdef CONFIG_TIME_NS

static struct page *find_timens_vvar_page(struct vm_area_struct *vma)

{

	if (likely(vma->vm_mm == current->mm))

		return current->nsproxy->time_ns->vvar_page;



	/*

	 * VM_PFNMAP | VM_IO protect .fault() handler from being called

	 * through interfaces like /proc/$pid/mem or

	 * process_vm_{readv,writev}() as long as there's no .access()

	 * in special_mapping_vmops().

	 * For more details check_vma_flags() and __access_remote_vm()

	 */



	WARN(1, "vvar_page accessed remotely");



	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
@@ -140,11 +122,6 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) 


	return 0;

}

#else

static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)

{

	return NULL;

}

#endif



static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,