security: define kernel_read_file hook

The kernel_read_file security hook is called prior to reading the file
into memory.

Changelog v4+:
- export security_kernel_read_file()

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 64cb3bc788c1..8aaa38666119 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -842,6 +842,10 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
 	if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0)
 		return -EINVAL;
 
+	ret = security_kernel_read_file(file, id);
+	if (ret)
+		return ret;
+
 	i_size = i_size_read(file_inode(file));
 	if (max_size > 0 && i_size > max_size)
 		return -EFBIG;