diff mbox series

[086/200] mremap: don't allow MREMAP_DONTUNMAP on special_mappings and aio

Message ID 20201215030813.I8VAWZGRf%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [001/200] kthread: add kthread_work tracepoints | expand

Commit Message

Andrew Morton Dec. 15, 2020, 3:08 a.m. UTC 
From: Dmitry Safonov <dima@arista.com>
Subject: mremap: don't allow MREMAP_DONTUNMAP on special_mappings and aio

As kernel expect to see only one of such mappings, any further operations
on the VMA-copy may be unexpected by the kernel.  Maybe it's being on the
safe side, but there doesn't seem to be any expected use-case for this, so
restrict it now.

Link: https://lkml.kernel.org/r/20201013013416.390574-4-dima@arista.com
Fixes: commit e346b3813067 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()")
Signed-off-by: Dmitry Safonov <dima@arista.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/x86/kernel/cpu/resctrl/pseudo_lock.c |    2 +-
 fs/aio.c                                  |    5 ++++-
 include/linux/mm.h                        |    2 +-
 mm/mmap.c                                 |    6 +++++-
 mm/mremap.c                               |    2 +-
 5 files changed, 12 insertions(+), 5 deletions(-)

Comments

Brian Geffon Dec. 28, 2020, 5:59 p.m. UTC | #1 
I don't think this situation can ever happen MREMAP_DONTUNMAP is
already restricted to anonymous mappings (defined as not having
vm_ops) and vma_to_resize checks that the mapping is anonymous before
move_vma is called.


On Mon, Dec 14, 2020 at 7:08 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> From: Dmitry Safonov <dima@arista.com>
> Subject: mremap: don't allow MREMAP_DONTUNMAP on special_mappings and aio
>
> As kernel expect to see only one of such mappings, any further operations
> on the VMA-copy may be unexpected by the kernel.  Maybe it's being on the
> safe side, but there doesn't seem to be any expected use-case for this, so
> restrict it now.
>
> Link: https://lkml.kernel.org/r/20201013013416.390574-4-dima@arista.com
> Fixes: commit e346b3813067 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()")
> Signed-off-by: Dmitry Safonov <dima@arista.com>
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Brian Geffon <bgeffon@google.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Dan Carpenter <dan.carpenter@oracle.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Dave Jiang <dave.jiang@intel.com>
> Cc: Hugh Dickins <hughd@google.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> Cc: Mike Kravetz <mike.kravetz@oracle.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Ralph Campbell <rcampbell@nvidia.com>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Vishal Verma <vishal.l.verma@intel.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Will Deacon <will@kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>
>  arch/x86/kernel/cpu/resctrl/pseudo_lock.c |    2 +-
>  fs/aio.c                                  |    5 ++++-
>  include/linux/mm.h                        |    2 +-
>  mm/mmap.c                                 |    6 +++++-
>  mm/mremap.c                               |    2 +-
>  5 files changed, 12 insertions(+), 5 deletions(-)
>
> --- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c~mremap-dont-allow-mremap_dontunmap-on-special_mappings-and-aio
> +++ a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
> @@ -1458,7 +1458,7 @@ static int pseudo_lock_dev_release(struc
>         return 0;
>  }
>
> -static int pseudo_lock_dev_mremap(struct vm_area_struct *area)
> +static int pseudo_lock_dev_mremap(struct vm_area_struct *area, unsigned long flags)
>  {
>         /* Not supported */
>         return -EINVAL;
> --- a/fs/aio.c~mremap-dont-allow-mremap_dontunmap-on-special_mappings-and-aio
> +++ a/fs/aio.c
> @@ -324,13 +324,16 @@ static void aio_free_ring(struct kioctx
>         }
>  }
>
> -static int aio_ring_mremap(struct vm_area_struct *vma)
> +static int aio_ring_mremap(struct vm_area_struct *vma, unsigned long flags)
>  {
>         struct file *file = vma->vm_file;
>         struct mm_struct *mm = vma->vm_mm;
>         struct kioctx_table *table;
>         int i, res = -EINVAL;
>
> +       if (flags & MREMAP_DONTUNMAP)
> +               return -EINVAL;
> +
>         spin_lock(&mm->ioctx_lock);
>         rcu_read_lock();
>         table = rcu_dereference(mm->ioctx_table);
> --- a/include/linux/mm.h~mremap-dont-allow-mremap_dontunmap-on-special_mappings-and-aio
> +++ a/include/linux/mm.h
> @@ -558,7 +558,7 @@ struct vm_operations_struct {
>         void (*open)(struct vm_area_struct * area);
>         void (*close)(struct vm_area_struct * area);
>         int (*split)(struct vm_area_struct * area, unsigned long addr);
> -       int (*mremap)(struct vm_area_struct * area);
> +       int (*mremap)(struct vm_area_struct *area, unsigned long flags);
>         vm_fault_t (*fault)(struct vm_fault *vmf);
>         vm_fault_t (*huge_fault)(struct vm_fault *vmf,
>                         enum page_entry_size pe_size);
> --- a/mm/mmap.c~mremap-dont-allow-mremap_dontunmap-on-special_mappings-and-aio
> +++ a/mm/mmap.c
> @@ -3405,10 +3405,14 @@ static const char *special_mapping_name(
>         return ((struct vm_special_mapping *)vma->vm_private_data)->name;
>  }
>
> -static int special_mapping_mremap(struct vm_area_struct *new_vma)
> +static int special_mapping_mremap(struct vm_area_struct *new_vma,
> +                                 unsigned long flags)
>  {
>         struct vm_special_mapping *sm = new_vma->vm_private_data;
>
> +       if (flags & MREMAP_DONTUNMAP)
> +               return -EINVAL;
> +
>         if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
>                 return -EFAULT;
>
> --- a/mm/mremap.c~mremap-dont-allow-mremap_dontunmap-on-special_mappings-and-aio
> +++ a/mm/mremap.c
> @@ -534,7 +534,7 @@ static unsigned long move_vma(struct vm_
>         if (moved_len < old_len) {
>                 err = -ENOMEM;
>         } else if (vma->vm_ops && vma->vm_ops->mremap) {
> -               err = vma->vm_ops->mremap(new_vma);
> +               err = vma->vm_ops->mremap(new_vma, flags);
>         }
>
>         if (unlikely(err)) {
> _
diff mbox series

Patch

--- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c~mremap-dont-allow-mremap_dontunmap-on-special_mappings-and-aio
+++ a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
@@ -1458,7 +1458,7 @@  static int pseudo_lock_dev_release(struc
 	return 0;
 }
 
-static int pseudo_lock_dev_mremap(struct vm_area_struct *area)
+static int pseudo_lock_dev_mremap(struct vm_area_struct *area, unsigned long flags)
 {
 	/* Not supported */
 	return -EINVAL;
--- a/fs/aio.c~mremap-dont-allow-mremap_dontunmap-on-special_mappings-and-aio
+++ a/fs/aio.c
@@ -324,13 +324,16 @@  static void aio_free_ring(struct kioctx
 	}
 }
 
-static int aio_ring_mremap(struct vm_area_struct *vma)
+static int aio_ring_mremap(struct vm_area_struct *vma, unsigned long flags)
 {
 	struct file *file = vma->vm_file;
 	struct mm_struct *mm = vma->vm_mm;
 	struct kioctx_table *table;
 	int i, res = -EINVAL;
 
+	if (flags & MREMAP_DONTUNMAP)
+		return -EINVAL;
+
 	spin_lock(&mm->ioctx_lock);
 	rcu_read_lock();
 	table = rcu_dereference(mm->ioctx_table);
--- a/include/linux/mm.h~mremap-dont-allow-mremap_dontunmap-on-special_mappings-and-aio
+++ a/include/linux/mm.h
@@ -558,7 +558,7 @@  struct vm_operations_struct {
 	void (*open)(struct vm_area_struct * area);
 	void (*close)(struct vm_area_struct * area);
 	int (*split)(struct vm_area_struct * area, unsigned long addr);
-	int (*mremap)(struct vm_area_struct * area);
+	int (*mremap)(struct vm_area_struct *area, unsigned long flags);
 	vm_fault_t (*fault)(struct vm_fault *vmf);
 	vm_fault_t (*huge_fault)(struct vm_fault *vmf,
 			enum page_entry_size pe_size);
--- a/mm/mmap.c~mremap-dont-allow-mremap_dontunmap-on-special_mappings-and-aio
+++ a/mm/mmap.c
@@ -3405,10 +3405,14 @@  static const char *special_mapping_name(
 	return ((struct vm_special_mapping *)vma->vm_private_data)->name;
 }
 
-static int special_mapping_mremap(struct vm_area_struct *new_vma)
+static int special_mapping_mremap(struct vm_area_struct *new_vma,
+				  unsigned long flags)
 {
 	struct vm_special_mapping *sm = new_vma->vm_private_data;
 
+	if (flags & MREMAP_DONTUNMAP)
+		return -EINVAL;
+
 	if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
 		return -EFAULT;
 
--- a/mm/mremap.c~mremap-dont-allow-mremap_dontunmap-on-special_mappings-and-aio
+++ a/mm/mremap.c
@@ -534,7 +534,7 @@  static unsigned long move_vma(struct vm_
 	if (moved_len < old_len) {
 		err = -ENOMEM;
 	} else if (vma->vm_ops && vma->vm_ops->mremap) {
-		err = vma->vm_ops->mremap(new_vma);
+		err = vma->vm_ops->mremap(new_vma, flags);
 	}
 
 	if (unlikely(err)) {