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, 6 deletions

diff --git a/include/linux/ima.h b/include/linux/ima.h
index d29a6a23fc19..7aea4863c244 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -19,7 +19,6 @@ extern int ima_file_check(struct file *file, int mask, int opened);
 extern void ima_file_free(struct file *file);
 extern int ima_file_mmap(struct file *file, unsigned long prot);
 extern int ima_module_check(struct file *file);
-extern int ima_fw_from_file(struct file *file, char *buf, size_t size);
 extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
 			      enum kernel_read_file_id id);
 
@@ -49,11 +48,6 @@ static inline int ima_module_check(struct file *file)
 	return 0;
 }
 
-static inline int ima_fw_from_file(struct file *file, char *buf, size_t size)
-{
-	return 0;
-}
-
 static inline int ima_post_read_file(struct file *file, void *buf, loff_t size,
 				     enum kernel_read_file_id id)
 {