[RFC PATCH 2/3] integrity: use call_read_iter to calculate the file hash

From: Mimi Zohar
Date: Thu Sep 28 2017 - 08:41:12 EST


This patch replaces the ->read file operation method in
integrity_kernel_read() with the newer ->read_iter and sets the
read_iter rwf flag to indicate that the i_rwsem has been taken
exclusively.

Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
---
security/integrity/iint.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/security/integrity/iint.c b/security/integrity/iint.c
index c84e05866052..df406bb96792 100644
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -16,11 +16,13 @@
* using a rbtree tree.
*/
#include <linux/slab.h>
+#include <linux/fs.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/rbtree.h>
#include <linux/file.h>
#include <linux/uaccess.h>
+#include <linux/uio.h>
#include "integrity.h"

static struct rb_root integrity_iint_tree = RB_ROOT;
@@ -184,18 +186,25 @@ security_initcall(integrity_iintcache_init);
int integrity_kernel_read(struct file *file, loff_t offset,
void *addr, unsigned long count)
{
- mm_segment_t old_fs;
- char __user *buf = (char __user *)addr;
+ struct inode *inode = file_inode(file);
+ struct kvec iov = { .iov_base = addr, .iov_len = count };
+ struct kiocb kiocb;
+ struct iov_iter iter;
ssize_t ret;

+ lockdep_assert_held(&inode->i_rwsem);
+
if (!(file->f_mode & FMODE_READ))
return -EBADF;
+ if (!file->f_op->read_iter)
+ return -EBADF;

- old_fs = get_fs();
- set_fs(get_ds());
- ret = __vfs_read(file, buf, count, &offset);
- set_fs(old_fs);
+ init_sync_kiocb(&kiocb, file);
+ kiocb.ki_pos = offset;
+ iov_iter_kvec(&iter, READ | ITER_KVEC, &iov, 1, count);

+ ret = call_read_iter(file, &kiocb, &iter, 1);
+ BUG_ON(ret == -EIOCBQUEUED);
return ret;
}

--
2.7.4