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    SubjectRe: [PATCH 0/6] kexec: A new system call to allow in kernel loading
    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


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