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, 20 insertions, 15 deletions

diff --git a/kernel/futex.c b/kernel/futex.c
index 054105854e0e..be3bff2315ff 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -481,13 +481,18 @@ static void drop_futex_key_refs(union futex_key *key)
 	}
 }
 
+enum futex_access {
+	FUTEX_READ,
+	FUTEX_WRITE
+};
+
 /**
  * get_futex_key() - Get parameters which are the keys for a futex
  * @uaddr:	virtual address of the futex
  * @fshared:	0 for a PROCESS_PRIVATE futex, 1 for PROCESS_SHARED
  * @key:	address where result is stored.
- * @rw:		mapping needs to be read/write (values: VERIFY_READ,
- *              VERIFY_WRITE)
+ * @rw:		mapping needs to be read/write (values: FUTEX_READ,
+ *              FUTEX_WRITE)
  *
  * Return: a negative error code or 0
  *
@@ -500,7 +505,7 @@ static void drop_futex_key_refs(union futex_key *key)
  * lock_page() might sleep, the caller should not hold a spinlock.
  */
 static int
-get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw)
+get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, enum futex_access rw)
 {
 	unsigned long address = (unsigned long)uaddr;
 	struct mm_struct *mm = current->mm;
@@ -516,7 +521,7 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw)
 		return -EINVAL;
 	address -= key->both.offset;
 
-	if (unlikely(!access_ok(rw, uaddr, sizeof(u32))))
+	if (unlikely(!access_ok(uaddr, sizeof(u32))))
 		return -EFAULT;
 
 	if (unlikely(should_fail_futex(fshared)))
@@ -546,7 +551,7 @@ again:
 	 * If write access is not required (eg. FUTEX_WAIT), try
 	 * and get read-only access.
 	 */
-	if (err == -EFAULT && rw == VERIFY_READ) {
+	if (err == -EFAULT && rw == FUTEX_READ) {
 		err = get_user_pages_fast(address, 1, 0, &page);
 		ro = 1;
 	}
@@ -1583,7 +1588,7 @@ futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset)
 	if (!bitset)
 		return -EINVAL;
 
-	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key, VERIFY_READ);
+	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key, FUTEX_READ);
 	if (unlikely(ret != 0))
 		goto out;
 
@@ -1642,7 +1647,7 @@ static int futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr)
 		oparg = 1 << oparg;
 	}
 
-	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
+	if (!access_ok(uaddr, sizeof(u32)))
 		return -EFAULT;
 
 	ret = arch_futex_atomic_op_inuser(op, oparg, &oldval, uaddr);
@@ -1682,10 +1687,10 @@ futex_wake_op(u32 __user *uaddr1, unsigned int flags, u32 __user *uaddr2,
 	DEFINE_WAKE_Q(wake_q);
 
 retry:
-	ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1, VERIFY_READ);
+	ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1, FUTEX_READ);
 	if (unlikely(ret != 0))
 		goto out;
-	ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE);
+	ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, FUTEX_WRITE);
 	if (unlikely(ret != 0))
 		goto out_put_key1;
 
@@ -1961,11 +1966,11 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
 	}
 
 retry:
-	ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1, VERIFY_READ);
+	ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1, FUTEX_READ);
 	if (unlikely(ret != 0))
 		goto out;
 	ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2,
-			    requeue_pi ? VERIFY_WRITE : VERIFY_READ);
+			    requeue_pi ? FUTEX_WRITE : FUTEX_READ);
 	if (unlikely(ret != 0))
 		goto out_put_key1;
 
@@ -2634,7 +2639,7 @@ static int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags,
 	 * while the syscall executes.
 	 */
 retry:
-	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q->key, VERIFY_READ);
+	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q->key, FUTEX_READ);
 	if (unlikely(ret != 0))
 		return ret;
 
@@ -2793,7 +2798,7 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
 	}
 
 retry:
-	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q.key, VERIFY_WRITE);
+	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q.key, FUTEX_WRITE);
 	if (unlikely(ret != 0))
 		goto out;
 
@@ -2972,7 +2977,7 @@ retry:
 	if ((uval & FUTEX_TID_MASK) != vpid)
 		return -EPERM;
 
-	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key, VERIFY_WRITE);
+	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key, FUTEX_WRITE);
 	if (ret)
 		return ret;
 
@@ -3199,7 +3204,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 	 */
 	rt_mutex_init_waiter(&rt_waiter);
 
-	ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE);
+	ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, FUTEX_WRITE);
 	if (unlikely(ret != 0))
 		goto out;