Messages in this thread | | | Subject | Re: [PATCH v13 2/6] powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c | From | Lakshmi Ramasubramanian <> | Date | Tue, 22 Dec 2020 21:03:05 -0800 |
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On 12/22/20 4:40 PM, Thiago Jung Bauermann wrote: > > Lakshmi Ramasubramanian <nramas@linux.microsoft.com> writes: > >> On 12/22/20 11:45 AM, Mimi Zohar wrote: >>> On Tue, 2020-12-22 at 10:53 -0800, Lakshmi Ramasubramanian wrote: >>>> On 12/22/20 6:26 AM, Mimi Zohar wrote: >>>> >>>> Hi Mimi, >>>> >>>>> >>>>> On Sat, 2020-12-19 at 09:57 -0800, Lakshmi Ramasubramanian wrote: >>>>>> >>>>>> diff --git a/arch/powerpc/kexec/Makefile b/arch/powerpc/kexec/Makefile >>>>>> index 4aff6846c772..b6c52608cb49 100644 >>>>>> --- a/arch/powerpc/kexec/Makefile >>>>>> +++ b/arch/powerpc/kexec/Makefile >>>>>> @@ -9,13 +9,6 @@ obj-$(CONFIG_PPC32) += relocate_32.o >>>>>> obj-$(CONFIG_KEXEC_FILE) += file_load.o ranges.o >>>>>> file_load_$(BITS).o elf_$(BITS).o >>>>>> -ifdef CONFIG_HAVE_IMA_KEXEC >>>>>> -ifdef CONFIG_IMA >>>>>> -obj-y += ima.o >>>>>> -endif >>>>>> -endif >>>>> >>>>> Notice how "kexec/ima.o" is only included if the architecture supports >>>>> it and IMA is configured. In addition only if CONFIG_IMA_KEXEC is >>>>> configured, is the IMA measurement list carried across kexec. After >>>>> moving the rest of ima.c to drivers/of/kexec.c, this changes. Notice >>>>> how drivers/of/Kconfig includes kexec.o: >>>>> >>>>> obj-$(CONFIG_KEXEC_FILE) += kexec.o >>>>> >>>>> It is not dependent on CONFIG_HAVE_IMA_KEXEC. Shouldn't all of the >>>>> functions defined in ima.c being moved to kexec.o be defined within a >>>>> CONFIG_HAVE_IMA_KEXEC ifdef? >>>>> >>>> >>>> Thanks for reviewing the changes. >>>> >>>> In "drivers/of/kexec.c" the function remove_ima_buffer() is defined >>>> under "#ifdef CONFIG_HAVE_IMA_KEXEC" >>>> >>>> setup_ima_buffer() is defined under "#ifdef CONFIG_IMA_KEXEC" - the same >>>> way it was defined in "arch/powerpc/kexec/ima.c". >>>> >>>> As you know, CONFIG_IMA_KEXEC depends on CONFIG_HAVE_IMA_KEXEC (as >>>> defined in "security/integrity/ima/Kconfig"). >>>> >>>> ima_get_kexec_buffer() and ima_free_kexec_buffer() are unconditionally >>>> defined in "drivers/of/kexec.c" even though they are called only when >>>> CONFIG_HAVE_IMA_KEXEC is enabled. I will update these two functions to >>>> be moved under "#ifdef CONFIG_HAVE_IMA_KEXEC" >>> The issue is the reverse. CONFIG_HAVE_IMA_KEXEC may be enabled without >>> CONFIG_IMA_KEXEC being enabled. This allows the architecture to >>> support carrying the measurement list across kexec, but requires >>> enabling it at build time. >>> Only if CONFIG_HAVE_IMA_KEXEC is enabled should any of these functions >>> be compiled at build. This allows restoring the previous IMA >>> measurement list, even if CONFIG_IMA_KEXEC is not enabled. >>> Only if CONFIG_IMA_KEXEC is enabled, should carrying the measurement >>> list across kexec be enabled. See how arch_ima_add_kexec_buffer, >>> write_number, setup_ima_buffer are ifdef'ed in >>> arch/powerpc/kexec/ima.c. >>> >> >> Yes - I agree. I will make the following changes: >> >> => Enable the functions moved from "arch/powerpc/kexec/ima.c" to >> "drivers/of/kexec.c" only when CONFIG_HAVE_IMA_KEXEC is enabled. >> >> => Also, compile write_number() and setup_ima_buffer() only when >> CONFIG_IMA_KEXEC is enabled. > > Sounds good, with one additional change: > > So far, CONFIG_HAVE_IMA_KEXEC was tested only in files that were built > when CONFIG_IMA was set. With this series this is not the case anymore > (in drivers/of/kexec.c). The simplest way to keep this consistent is to > only enable CONFIG_HAVE_IMA_KEXEC if CONFIG_IMA is also set. > > For example, with this: > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index e9f13fe08492..4ddd17215ecf 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -548,7 +548,7 @@ config KEXEC > config KEXEC_FILE > bool "kexec file based system call" > select KEXEC_CORE > - select HAVE_IMA_KEXEC > + select HAVE_IMA_KEXEC if IMA > select BUILD_BIN2C > select KEXEC_ELF > depends on PPC64 > > And then the same thing on the arm64 patch.
This is a good idea Thiago - I will make this change in the Kconfig for both powerpc and arm64.
thanks, -lakshmi
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