On Thu, Nov 21, 2013 at 10:58:28AM -0800, Greg KH wrote: > On Wed, Nov 20, 2013 at 12:50:45PM -0500, Vivek Goyal wrote: > > 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. > > Very good stuff, thanks for working on this. How have you been testing > this on the userspace side? Are there patches to kexec, or are you just > using a small test program with the new syscall? I wrote a patch for kexec-tools. One can choose to use new system call by passing command line option --use-kexec2-syscall. I will post that patch soon in this mail thread. Thanks Vivek
