Current proposed secureboot implementation disables kexec/kdump because it can allow unsigned kernel to run on a secureboot platform. Intial idea was to sign /sbin/kexec binary and let that binary do the kernel signature verification. I had posted RFC patches for this apparoach here. https://lkml.org/lkml/2013/9/10/560 Later we had discussion at Plumbers and most of the people thought that signing and trusting /sbin/kexec is becoming complex. So a better idea might be let kernel do the signature verification of new kernel being loaded. This calls for implementing a new system call and moving lot of user space code in kernel. kexec_load() system call allows loading a kexec/kdump kernel and jump to that kernel at right time. Though a lot of processing is done in user space which prepares a list of segments/buffers to be loaded and kexec_load() works on that list of segments. It does not know what's contained in those segments. Now a new system call kexec_file_load() is implemented which takes kernel fd and initrd fd as parameters. Now kernel should be able to verify signature of newly loaded kernel. This is an early RFC patchset. I have not done signature handling part yet. This is more of a minimal patch to show how new system call and functionality will look like. Right now it can only handle bzImage with 64bit entry point on x86_64. No EFI, no x86_32 or any other architecture. Rest of the things can be added slowly as need arises. In first iteration, I have tried to address most common use case for us. Any feedback is welcome. Vivek Goyal (6): kexec: Export vmcoreinfo note size properly kexec: Move segment verification code in a separate function resource: Provide new functions to walk through resources kexec: A new system call, kexec_file_load, for in kernel kexec kexec-bzImage: Support for loading bzImage using 64bit entry kexec: Support for Kexec on panic using new system call arch/x86/include/asm/crash.h | 9 + arch/x86/include/asm/kexec-bzimage.h | 12 + arch/x86/include/asm/kexec.h | 43 ++ arch/x86/kernel/Makefile | 2 + arch/x86/kernel/crash.c | 585 +++++++++++++++++++++++++++ arch/x86/kernel/kexec-bzimage.c | 420 +++++++++++++++++++ arch/x86/kernel/machine_kexec_64.c | 60 +++- arch/x86/kernel/purgatory_entry_64.S | 119 ++++++ arch/x86/syscalls/syscall_64.tbl | 1 + include/linux/ioport.h | 6 + include/linux/kexec.h | 57 +++ include/linux/syscalls.h | 3 + include/uapi/linux/kexec.h | 4 + kernel/kexec.c | 731 ++++++++++++++++++++++++++++++---- kernel/ksysfs.c | 2 +- kernel/resource.c | 108 +++++- kernel/sys_ni.c | 1 + 17 files changed, 2074 insertions(+), 89 deletions(-) create mode 100644 arch/x86/include/asm/crash.h create mode 100644 arch/x86/include/asm/kexec-bzimage.h create mode 100644 arch/x86/kernel/kexec-bzimage.c create mode 100644 arch/x86/kernel/purgatory_entry_64.S -- 1.7.7.6
