firmware: replace call to fw_read_file_contents() with kernel version

Replace the fw_read_file_contents with kernel_file_read_from_path().

Although none of the upstreamed LSMs define a kernel_fw_from_file hook,
IMA is called by the security function to prevent unsigned firmware from
being loaded and to measure/appraise signed firmware, based on policy.

Instead of reading the firmware twice, once for measuring/appraising the
firmware and again for reading the firmware contents into memory, the
kernel_post_read_file() security hook calculates the file hash based on
the in memory file buffer.  The firmware is read once.

This patch removes the LSM kernel_fw_from_file() hook and security call.

Changelog v4+:
- revert dropped buf->size assignment - reported by Sergey Senozhatsky
v3:
- remove kernel_fw_from_file hook
- use kernel_file_read_from_path() - requested by Luis
v2:
- reordered and squashed firmware patches
- fix MAX firmware size (Kees Cook)

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>

1 files changed, 0 insertions, 7 deletions

diff --git a/include/linux/security.h b/include/linux/security.h
index d920718dc845..cee1349e1155 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -300,7 +300,6 @@ int security_prepare_creds(struct cred *new, const struct cred *old, gfp_t gfp);
 void security_transfer_creds(struct cred *new, const struct cred *old);
 int security_kernel_act_as(struct cred *new, u32 secid);
 int security_kernel_create_files_as(struct cred *new, struct inode *inode);
-int security_kernel_fw_from_file(struct file *file, char *buf, size_t size);
 int security_kernel_module_request(char *kmod_name);
 int security_kernel_module_from_file(struct file *file);
 int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
@@ -854,12 +853,6 @@ static inline int security_kernel_create_files_as(struct cred *cred,
 	return 0;
 }
 
-static inline int security_kernel_fw_from_file(struct file *file,
-					       char *buf, size_t size)
-{
-	return 0;
-}
-
 static inline int security_kernel_module_request(char *kmod_name)
 {
 	return 0;