integrity: define a new function integrity_read_file()

This patch defines a new function called integrity_read_file()
to read file from the kernel into a buffer. Subsequent patches
will read a file containing the public keys and load them onto
the IMA keyring.

This patch moves and renames ima_kernel_read(), the non-security
checking version of kernel_read(), to integrity_kernel_read().

Changes in v3:
* Patch descriptions improved (Mimi)
* Add missing cast (kbuild test robot)

Changes in v2:
* configuration option removed
* function declared as '__init'

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

1 files changed, 3 insertions, 32 deletions

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index d34e7dfc1118..5df4d960d4dc 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -67,36 +67,6 @@ MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size");
 static struct crypto_shash *ima_shash_tfm;
 static struct crypto_ahash *ima_ahash_tfm;
 
-/**
- * ima_kernel_read - read file content
- *
- * This is a function for reading file content instead of kernel_read().
- * It does not perform locking checks to ensure it cannot be blocked.
- * It does not perform security checks because it is irrelevant for IMA.
- *
- */
-static int ima_kernel_read(struct file *file, loff_t offset,
-			   char *addr, unsigned long count)
-{
-	mm_segment_t old_fs;
-	char __user *buf = addr;
-	ssize_t ret = -EINVAL;
-
-	if (!(file->f_mode & FMODE_READ))
-		return -EBADF;
-
-	old_fs = get_fs();
-	set_fs(get_ds());
-	if (file->f_op->read)
-		ret = file->f_op->read(file, buf, count, &offset);
-	else if (file->f_op->aio_read)
-		ret = do_sync_read(file, buf, count, &offset);
-	else if (file->f_op->read_iter)
-		ret = new_sync_read(file, buf, count, &offset);
-	set_fs(old_fs);
-	return ret;
-}
-
 int __init ima_init_crypto(void)
 {
 	long rc;
@@ -324,7 +294,8 @@ static int ima_calc_file_hash_atfm(struct file *file,
 		}
 		/* read buffer */
 		rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
-		rc = ima_kernel_read(file, offset, rbuf[active], rbuf_len);
+		rc = integrity_kernel_read(file, offset, rbuf[active],
+					   rbuf_len);
 		if (rc != rbuf_len)
 			goto out3;
 
@@ -417,7 +388,7 @@ static int ima_calc_file_hash_tfm(struct file *file,
 	while (offset < i_size) {
 		int rbuf_len;
 
-		rbuf_len = ima_kernel_read(file, offset, rbuf, PAGE_SIZE);
+		rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
 		if (rbuf_len < 0) {
 			rc = rbuf_len;
 			break;