Remove 'type' argument from access_ok() function

Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.

It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access.  But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.

A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model.  And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.

This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.

There were a couple of notable cases:

 - csky still had the old "verify_area()" name as an alias.

 - the iter_iov code had magical hardcoded knowledge of the actual
   values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
   really used it)

 - microblaze used the type argument for a debug printout

but other than those oddities this should be a total no-op patch.

I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something.  Any missed conversion should be trivially fixable, though.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 8 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index 58f30537c47a..ff3c5e6f87cf 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -442,7 +442,7 @@ ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
 		return -EBADF;
 	if (!(file->f_mode & FMODE_CAN_READ))
 		return -EINVAL;
-	if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
+	if (unlikely(!access_ok(buf, count)))
 		return -EFAULT;
 
 	ret = rw_verify_area(READ, file, pos, count);
@@ -538,7 +538,7 @@ ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_
 		return -EBADF;
 	if (!(file->f_mode & FMODE_CAN_WRITE))
 		return -EINVAL;
-	if (unlikely(!access_ok(VERIFY_READ, buf, count)))
+	if (unlikely(!access_ok(buf, count)))
 		return -EFAULT;
 
 	ret = rw_verify_area(WRITE, file, pos, count);
@@ -718,9 +718,6 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
 	return ret;
 }
 
-/* A write operation does a read from user space and vice versa */
-#define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
-
 /**
  * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace
  *     into the kernel and check that it is valid.
@@ -810,7 +807,7 @@ ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
 			goto out;
 		}
 		if (type >= 0
-		    && unlikely(!access_ok(vrfy_dir(type), buf, len))) {
+		    && unlikely(!access_ok(buf, len))) {
 			ret = -EFAULT;
 			goto out;
 		}
@@ -856,7 +853,7 @@ ssize_t compat_rw_copy_check_uvector(int type,
 	*ret_pointer = iov;
 
 	ret = -EFAULT;
-	if (!access_ok(VERIFY_READ, uvector, nr_segs*sizeof(*uvector)))
+	if (!access_ok(uvector, nr_segs*sizeof(*uvector)))
 		goto out;
 
 	/*
@@ -881,7 +878,7 @@ ssize_t compat_rw_copy_check_uvector(int type,
 		if (len < 0)	/* size_t not fitting in compat_ssize_t .. */
 			goto out;
 		if (type >= 0 &&
-		    !access_ok(vrfy_dir(type), compat_ptr(buf), len)) {
+		    !access_ok(compat_ptr(buf), len)) {
 			ret = -EFAULT;
 			goto out;
 		}