[PATCH v2 4/7] kexec: update kexec_file_load syscall to call ima_kexec_post_load

[Tushar Sugandhi]

The kexec_file_load() syscall is used to load a new Kernel for kexec.
The syscall needs to be updated to call ima_kexec_post_load(),
which was implemented in a previous patch.  ima_kexec_post_load() should
take care of mapping the IMA log buffer segment into the next Kernel. It
should also register a reboot notifier which would call a function to
dump the IMA measurements into IMA log buffer segment during kexec soft
reboot.

Modify the kexec_file_load() syscall to call ima_kexec_post_load() after
the image has been loaded and prepared for kexec.  This ensures that the
IMA measurement list will be available to the next Kernel after a kexec
soft reboot.  This also ensures the measurements taken in the window
between kexec 'load' and 'execute' are captured and passed to the next
Kernel.

Signed-off-by: Tushar Sugandhi <tusharsu at linux.microsoft.com>
---
 kernel/kexec_file.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index f989f5f1933b..617dbbb6e46d 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -184,6 +184,11 @@ kimage_validate_signature(struct kimage *image)
 }
 #endif
 
+void kimage_file_post_load(struct kimage *image)
+{
+	ima_kexec_post_load(image);
+}
+
 /*
  * In file mode list of segments is prepared by kernel. Copy relevant
  * data from user space, do error checking, prepare segment list
@@ -399,6 +404,9 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 
 	kimage_terminate(image);
 
+	if (!(flags & KEXEC_FILE_ON_CRASH))
+		kimage_file_post_load(image);
+
 	ret = machine_kexec_post_load(image);
 	if (ret)
 		goto out;
-- 
2.25.1