[PATCH 0/7] Ksplice: Rebootless kernel updates

Jeff Arnold
2008-12-06T00:06:49Z

Hello Andrew,

We're interested in having Ksplice included in -mm. If you could consider
this code for inclusion (or let us know what you'd like us to do next),
we'd appreciate it.

==

These patches add support for Ksplice [1], a rebootless update system, to
the kernel.

[1] http://www.ksplice.com/download

I previously mentioned Ksplice to the LKML in April [2], and I submitted
RFC patches to the LKML in September [3] and November [4]. The basic idea
is that Ksplice can apply an update to a running Linux kernel based only
on a source code patch and the original kernel source. The Ksplice
technical overview document [5] describes the design of Ksplice and one of
the ways that Ksplice has been evaluated.

[2] http://lkml.org/lkml/2008/4/23/330
[3] http://lkml.org/lkml/2008/9/13/6
[4] http://lkml.org/lkml/2008/11/21/484
[5] http://www.ksplice.com/doc/ksplice.pdf

Specifically, Ksplice has been used to correct every significant Linux
kernel CVE from May 2005 to May 2008 [6]. 88% of these CVEs can be fixed
without writing any new code at all; the remaining 12% of CVEs require a
minimal amount of new code (on average, roughly 20 new
semicolon-terminated lines per CVE).

[6] http://www.ksplice.com/cve-evaluation

The interface between the Ksplice kernel component and the userspace
utilities is documented in the last patch of this series. The current
implementation of the userspace utilities is available from the Ksplice
website and the Ksplice git repository [7]. The Ksplice userspace
utilities transparently support both "integrated" operation (updating a
kernel patched with this patch series) and "standalone" operation
(updating a completely unmodified kernel).

[7] http://www.ksplice.com/git/ksplice.git

Just to let you know what direction we are going in: We're currently
working on the problem of making it feasible to apply the entire stable
tree using Ksplice. Although Ksplice's original evaluation focused on
patches for CVEs, we understand the idea that "security bugs are just
'normal bugs'" [8] (i.e., tracking security bugs separately from normal
bugs can be difficult and isn't necessarily advisable). We ultimately
want to provide to long-running machines hot updates for all of the bug
fixes that go into the corresponding stable tree. We think that
long-running machines will be more secure and reliable if they can
regularly be updated to the latest stable kernel code (along with the
usual user space updates provided by distributions).

[8] http://lkml.org/lkml/2008/7/14/465

Even though work on Ksplice is ongoing, I think that merging Ksplice makes
sense at this point because (1) development on the Ksplice kernel code has
stabilized, and (2) the system, as it currently stands, can be useful in a
variety of situations.

Jeff Arnold
jbarnold@mit.edu

Changes since v3:
- removed use of init_mm, as requested by Christoph Hellwig

Changes since v2:
- added taint flag, as requested by Alexey Dobriyan
- various speed optimizations
- support for replacing functions mapped read-only (CONFIG_DEBUG_RODATA)
- run-pre matching extended to bug table, ex_table, exported symbol table
- added hooks for calling custom code during the update process
- struct ksplice_export eliminated (struct ksplice_patch used instead)
- minor sysfs API changes
- added support for ksplice-apply's --partial option
- improved -ffunction-sections patches and added them to this patch series
- dropped ARM support for now, for simplicity

No changes between v1 and v2.

==

Documentation/ksplice.txt | 282 ++
Documentation/mutex-design.txt | 4 +-
MAINTAINERS | 10 +
Makefile | 4 +
arch/Kconfig | 14 +
arch/alpha/kernel/head.S | 2 +-
arch/alpha/kernel/init_task.c | 2 +-
arch/alpha/kernel/vmlinux.lds.S | 14 +-
arch/arm/kernel/head-nommu.S | 3 +-
arch/arm/kernel/head.S | 3 +-
arch/arm/kernel/init_task.c | 2 +-
arch/arm/kernel/vmlinux.lds.S | 14 +-
arch/arm/mm/proc-v6.S | 2 +-
arch/arm/mm/proc-v7.S | 2 +-
arch/arm/mm/tlb-v6.S | 2 +-
arch/arm/mm/tlb-v7.S | 2 +-
arch/avr32/kernel/init_task.c | 2 +-
arch/avr32/kernel/vmlinux.lds.S | 6 +-
arch/avr32/mm/init.c | 2 +-
arch/blackfin/kernel/vmlinux.lds.S | 2 +-
arch/cris/kernel/process.c | 2 +-
arch/frv/kernel/break.S | 4 +-
arch/frv/kernel/entry.S | 2 +-
arch/frv/kernel/head-mmu-fr451.S | 2 +-
arch/frv/kernel/head-uc-fr401.S | 2 +-
arch/frv/kernel/head-uc-fr451.S | 2 +-
arch/frv/kernel/head-uc-fr555.S | 2 +-
arch/frv/kernel/head.S | 4 +-
arch/frv/kernel/init_task.c | 2 +-
arch/frv/kernel/vmlinux.lds.S | 18 +-
arch/frv/mm/tlb-miss.S | 2 +-
arch/h8300/boot/compressed/head.S | 2 +-
arch/h8300/boot/compressed/vmlinux.lds | 2 +-
arch/h8300/kernel/init_task.c | 2 +-
arch/h8300/kernel/vmlinux.lds.S | 2 +-
arch/ia64/include/asm/asmmacro.h | 12 +-
arch/ia64/include/asm/cache.h | 2 +-
arch/ia64/include/asm/percpu.h | 2 +-
arch/ia64/kernel/Makefile | 2 +-
arch/ia64/kernel/gate-data.S | 2 +-
arch/ia64/kernel/gate.S | 8 +-
arch/ia64/kernel/gate.lds.S | 10 +-
arch/ia64/kernel/head.S | 2 +-
arch/ia64/kernel/init_task.c | 4 +-
arch/ia64/kernel/ivt.S | 2 +-
arch/ia64/kernel/minstate.h | 4 +-
arch/ia64/kernel/paravirtentry.S | 12 +-
arch/ia64/kernel/vmlinux.lds.S | 48 +-
arch/ia64/kvm/vmm_ivt.S | 2 +-
arch/ia64/xen/xensetup.S | 2 +-
arch/m32r/kernel/init_task.c | 2 +-
arch/m32r/kernel/vmlinux.lds.S | 6 +-
arch/m68k/kernel/head.S | 2 +-
arch/m68k/kernel/process.c | 2 +-
arch/m68k/kernel/sun3-head.S | 2 +-
arch/m68k/kernel/vmlinux-std.lds | 6 +-
arch/m68k/kernel/vmlinux-sun3.lds | 4 +-
arch/m68knommu/kernel/init_task.c | 2 +-
arch/m68knommu/kernel/vmlinux.lds.S | 6 +-
arch/m68knommu/platform/68360/head-ram.S | 2 +-
arch/m68knommu/platform/68360/head-rom.S | 2 +-
arch/mips/kernel/init_task.c | 2 +-
arch/mips/kernel/vmlinux.lds.S | 8 +-
arch/mips/lasat/image/head.S | 2 +-
arch/mips/lasat/image/romscript.normal | 2 +-
arch/mn10300/kernel/head.S | 2 +-
arch/mn10300/kernel/init_task.c | 2 +-
arch/mn10300/kernel/vmlinux.lds.S | 18 +-
arch/parisc/include/asm/cache.h | 2 +-
arch/parisc/include/asm/system.h | 2 +-
arch/parisc/kernel/head.S | 2 +-
arch/parisc/kernel/init_task.c | 8 +-
arch/parisc/kernel/vmlinux.lds.S | 26 +-
arch/powerpc/include/asm/cache.h | 2 +-
arch/powerpc/include/asm/page_64.h | 2 +-
arch/powerpc/include/asm/ppc_asm.h | 4 +-
arch/powerpc/kernel/head_32.S | 2 +-
arch/powerpc/kernel/head_40x.S | 2 +-
arch/powerpc/kernel/head_44x.S | 2 +-
arch/powerpc/kernel/head_8xx.S | 2 +-
arch/powerpc/kernel/head_fsl_booke.S | 2 +-
arch/powerpc/kernel/init_task.c | 2 +-
arch/powerpc/kernel/machine_kexec_64.c | 2 +-
arch/powerpc/kernel/vdso.c | 2 +-
arch/powerpc/kernel/vdso32/vdso32_wrapper.S | 2 +-
arch/powerpc/kernel/vdso64/vdso64_wrapper.S | 2 +-
arch/powerpc/kernel/vmlinux.lds.S | 28 +-
arch/s390/include/asm/cache.h | 2 +-
arch/s390/kernel/head.S | 2 +-
arch/s390/kernel/init_task.c | 2 +-
arch/s390/kernel/vmlinux.lds.S | 20 +-
arch/sh/include/asm/cache.h | 2 +-
arch/sh/kernel/cpu/sh5/entry.S | 4 +-
arch/sh/kernel/head_32.S | 2 +-
arch/sh/kernel/head_64.S | 2 +-
arch/sh/kernel/init_task.c | 2 +-
arch/sh/kernel/irq.c | 4 +-
arch/sh/kernel/vmlinux_32.lds.S | 14 +-
arch/sh/kernel/vmlinux_64.lds.S | 14 +-
arch/sparc/boot/btfixupprep.c | 4 +-
arch/sparc/include/asm/cache.h | 2 +-
arch/sparc/kernel/head.S | 2 +-
arch/sparc/kernel/vmlinux.lds.S | 8 +-
arch/sparc64/kernel/head.S | 2 +-
arch/sparc64/kernel/vmlinux.lds.S | 8 +-
arch/um/include/asm/common.lds.S | 4 +-
arch/um/kernel/dyn.lds.S | 4 +-
arch/um/kernel/init_task.c | 4 +-
arch/um/kernel/uml.lds.S | 4 +-
arch/x86/Kconfig | 1 +
arch/x86/boot/compressed/head_32.S | 2 +-
arch/x86/boot/compressed/head_64.S | 2 +-
arch/x86/boot/compressed/vmlinux.scr | 2 +-
arch/x86/boot/compressed/vmlinux_32.lds | 14 +-
arch/x86/boot/compressed/vmlinux_64.lds | 10 +-
arch/x86/include/asm/cache.h | 4 +-
arch/x86/kernel/acpi/wakeup_32.S | 2 +-
arch/x86/kernel/head_32.S | 6 +-
arch/x86/kernel/head_64.S | 4 +-
arch/x86/kernel/init_task.c | 4 +-
arch/x86/kernel/ksplice-arch.c | 125 +
arch/x86/kernel/traps.c | 2 +-
arch/x86/kernel/vmlinux_32.lds.S | 37 +-
arch/x86/kernel/vmlinux_64.lds.S | 27 +-
arch/xtensa/kernel/head.S | 2 +-
arch/xtensa/kernel/init_task.c | 2 +-
arch/xtensa/kernel/vmlinux.lds.S | 6 +-
include/asm-frv/init.h | 8 +-
include/asm-generic/vmlinux.lds.h | 16 +-
include/linux/cache.h | 2 +-
include/linux/init.h | 8 +-
include/linux/kallsyms.h | 13 +
include/linux/kernel.h | 1 +
include/linux/ksplice.h | 212 ++
include/linux/linkage.h | 4 +-
include/linux/module.h | 42 +
include/linux/percpu.h | 12 +-
include/linux/spinlock.h | 2 +-
kernel/Makefile | 3 +
kernel/extable.c | 3 +
kernel/kallsyms.c | 19 +
kernel/ksplice.c | 2715 +++++++++++++++++++
kernel/module.c | 164 +-
kernel/panic.c | 1 +
kernel/sched.c | 1 +
lib/Kconfig.debug | 9 +
lib/bug.c | 1 +
scripts/Makefile.modpost | 1 +
scripts/mod/modpost.c | 22 +-
scripts/recordmcount.pl | 6 +-
150 files changed, 3927 insertions(+), 408 deletions(-)

Jeff Arnold
jbarnold@mit.edu