[v16,09/16] fs, arm64: untag user pointers in fs/userfaultfd.c
diff mbox series

Message ID 7d6fef00d7daf647b5069101da8cf5a202da75b0.1559580831.git.andreyknvl@google.com
State New
Headers show
Series
  • arm64: untag user pointers passed to the kernel
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Commit Message

Andrey Konovalov June 3, 2019, 4:55 p.m. UTC
This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

userfaultfd code use provided user pointers for vma lookups, which can
only by done with untagged pointers.

Untag user pointers in validate_range().

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 fs/userfaultfd.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

Comments

Kees Cook June 8, 2019, 4:03 a.m. UTC | #1
On Mon, Jun 03, 2019 at 06:55:11PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> userfaultfd code use provided user pointers for vma lookups, which can
> only by done with untagged pointers.
> 
> Untag user pointers in validate_range().
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

"userfaultfd: untag user pointers"

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  fs/userfaultfd.c | 22 ++++++++++++----------
>  1 file changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> index 3b30301c90ec..24d68c3b5ee2 100644
> --- a/fs/userfaultfd.c
> +++ b/fs/userfaultfd.c
> @@ -1263,21 +1263,23 @@ static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx,
>  }
>  
>  static __always_inline int validate_range(struct mm_struct *mm,
> -					  __u64 start, __u64 len)
> +					  __u64 *start, __u64 len)
>  {
>  	__u64 task_size = mm->task_size;
>  
> -	if (start & ~PAGE_MASK)
> +	*start = untagged_addr(*start);
> +
> +	if (*start & ~PAGE_MASK)
>  		return -EINVAL;
>  	if (len & ~PAGE_MASK)
>  		return -EINVAL;
>  	if (!len)
>  		return -EINVAL;
> -	if (start < mmap_min_addr)
> +	if (*start < mmap_min_addr)
>  		return -EINVAL;
> -	if (start >= task_size)
> +	if (*start >= task_size)
>  		return -EINVAL;
> -	if (len > task_size - start)
> +	if (len > task_size - *start)
>  		return -EINVAL;
>  	return 0;
>  }
> @@ -1327,7 +1329,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
>  		goto out;
>  	}
>  
> -	ret = validate_range(mm, uffdio_register.range.start,
> +	ret = validate_range(mm, &uffdio_register.range.start,
>  			     uffdio_register.range.len);
>  	if (ret)
>  		goto out;
> @@ -1516,7 +1518,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
>  	if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister)))
>  		goto out;
>  
> -	ret = validate_range(mm, uffdio_unregister.start,
> +	ret = validate_range(mm, &uffdio_unregister.start,
>  			     uffdio_unregister.len);
>  	if (ret)
>  		goto out;
> @@ -1667,7 +1669,7 @@ static int userfaultfd_wake(struct userfaultfd_ctx *ctx,
>  	if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake)))
>  		goto out;
>  
> -	ret = validate_range(ctx->mm, uffdio_wake.start, uffdio_wake.len);
> +	ret = validate_range(ctx->mm, &uffdio_wake.start, uffdio_wake.len);
>  	if (ret)
>  		goto out;
>  
> @@ -1707,7 +1709,7 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
>  			   sizeof(uffdio_copy)-sizeof(__s64)))
>  		goto out;
>  
> -	ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len);
> +	ret = validate_range(ctx->mm, &uffdio_copy.dst, uffdio_copy.len);
>  	if (ret)
>  		goto out;
>  	/*
> @@ -1763,7 +1765,7 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
>  			   sizeof(uffdio_zeropage)-sizeof(__s64)))
>  		goto out;
>  
> -	ret = validate_range(ctx->mm, uffdio_zeropage.range.start,
> +	ret = validate_range(ctx->mm, &uffdio_zeropage.range.start,
>  			     uffdio_zeropage.range.len);
>  	if (ret)
>  		goto out;
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
>
Catalin Marinas June 12, 2019, 10:45 a.m. UTC | #2
On Mon, Jun 03, 2019 at 06:55:11PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> userfaultfd code use provided user pointers for vma lookups, which can
> only by done with untagged pointers.
> 
> Untag user pointers in validate_range().
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Patch
diff mbox series

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 3b30301c90ec..24d68c3b5ee2 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1263,21 +1263,23 @@  static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx,
 }
 
 static __always_inline int validate_range(struct mm_struct *mm,
-					  __u64 start, __u64 len)
+					  __u64 *start, __u64 len)
 {
 	__u64 task_size = mm->task_size;
 
-	if (start & ~PAGE_MASK)
+	*start = untagged_addr(*start);
+
+	if (*start & ~PAGE_MASK)
 		return -EINVAL;
 	if (len & ~PAGE_MASK)
 		return -EINVAL;
 	if (!len)
 		return -EINVAL;
-	if (start < mmap_min_addr)
+	if (*start < mmap_min_addr)
 		return -EINVAL;
-	if (start >= task_size)
+	if (*start >= task_size)
 		return -EINVAL;
-	if (len > task_size - start)
+	if (len > task_size - *start)
 		return -EINVAL;
 	return 0;
 }
@@ -1327,7 +1329,7 @@  static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 		goto out;
 	}
 
-	ret = validate_range(mm, uffdio_register.range.start,
+	ret = validate_range(mm, &uffdio_register.range.start,
 			     uffdio_register.range.len);
 	if (ret)
 		goto out;
@@ -1516,7 +1518,7 @@  static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 	if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister)))
 		goto out;
 
-	ret = validate_range(mm, uffdio_unregister.start,
+	ret = validate_range(mm, &uffdio_unregister.start,
 			     uffdio_unregister.len);
 	if (ret)
 		goto out;
@@ -1667,7 +1669,7 @@  static int userfaultfd_wake(struct userfaultfd_ctx *ctx,
 	if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake)))
 		goto out;
 
-	ret = validate_range(ctx->mm, uffdio_wake.start, uffdio_wake.len);
+	ret = validate_range(ctx->mm, &uffdio_wake.start, uffdio_wake.len);
 	if (ret)
 		goto out;
 
@@ -1707,7 +1709,7 @@  static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
 			   sizeof(uffdio_copy)-sizeof(__s64)))
 		goto out;
 
-	ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len);
+	ret = validate_range(ctx->mm, &uffdio_copy.dst, uffdio_copy.len);
 	if (ret)
 		goto out;
 	/*
@@ -1763,7 +1765,7 @@  static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
 			   sizeof(uffdio_zeropage)-sizeof(__s64)))
 		goto out;
 
-	ret = validate_range(ctx->mm, uffdio_zeropage.range.start,
+	ret = validate_range(ctx->mm, &uffdio_zeropage.range.start,
 			     uffdio_zeropage.range.len);
 	if (ret)
 		goto out;