Re: [PATCH v3 0/9] Support strict kernel memory permissions for security

From: Zong Li <zong.li@sifive.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	linux-riscv <linux-riscv@lists.infradead.org>,
	"linux-kernel@vger.kernel.org List"
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 0/9] Support strict kernel memory permissions for security
Date: Wed, 1 Apr 2020 15:18:52 +0800	[thread overview]
Message-ID: <CANXhq0rD5kWf=ZDeA0bWdnd2A_iFS-mX_=X8DdJTH4fw09_sKQ@mail.gmail.com> (raw)
In-Reply-To: <20200331223254.919b92750962fefed5a6646f@kernel.org>

On Tue, Mar 31, 2020 at 9:32 PM Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> Hi Zong,
>
> On Tue, 10 Mar 2020 00:55:35 +0800
> Zong Li <zong.li@sifive.com> wrote:
>
> > The main purpose of this patch series is changing the kernel mapping permission
> > , make sure that code is not writeable, data is not executable, and read-only
> > data is neither writable nor executable.
> >
> > This patch series also supports the relevant implementations such as
> > ARCH_HAS_SET_MEMORY, ARCH_HAS_SET_DIRECT_MAP,
> > ARCH_SUPPORTS_DEBUG_PAGEALLOC and DEBUG_WX.
>
> The order of the patches seems a bit strange. Since the first 7 patches
> makes kernel read-only, at that point ftrace is broken and it is fixed
> by the last 2 patches. That is not bisect-friendly. Can you move the
> last 2 patches to the top?
>

OK. Let me rearrange the order. Thanks.

> Thank you,
>
> >
> > Changes in v3:
> >  - Fix build error on nommu configuration. We already support nommu on
> >    RISC-V, so we should consider nommu case and test not only rv32/64,
> >    but also nommu.
> >
> > Changes in v2:
> >  - Use _data to specify the start of data section with write permission.
> >  - Change ftrace patch text implementaion.
> >  - Separate DEBUG_WX patch to another patchset.
> >
> > Zong Li (9):
> >   riscv: add ARCH_HAS_SET_MEMORY support
> >   riscv: add ARCH_HAS_SET_DIRECT_MAP support
> >   riscv: add ARCH_SUPPORTS_DEBUG_PAGEALLOC support
> >   riscv: move exception table immediately after RO_DATA
> >   riscv: add alignment for text, rodata and data sections
> >   riscv: add STRICT_KERNEL_RWX support
> >   riscv: add macro to get instruction length
> >   riscv: introduce interfaces to patch kernel code
> >   riscv: patch code by fixmap mapping
> >
> >  arch/riscv/Kconfig                  |   6 +
> >  arch/riscv/include/asm/bug.h        |   8 ++
> >  arch/riscv/include/asm/fixmap.h     |   2 +
> >  arch/riscv/include/asm/patch.h      |  12 ++
> >  arch/riscv/include/asm/set_memory.h |  48 +++++++
> >  arch/riscv/kernel/Makefile          |   4 +-
> >  arch/riscv/kernel/ftrace.c          |  13 +-
> >  arch/riscv/kernel/patch.c           | 120 ++++++++++++++++++
> >  arch/riscv/kernel/traps.c           |   3 +-
> >  arch/riscv/kernel/vmlinux.lds.S     |  11 +-
> >  arch/riscv/mm/Makefile              |   2 +-
> >  arch/riscv/mm/init.c                |  44 +++++++
> >  arch/riscv/mm/pageattr.c            | 187 ++++++++++++++++++++++++++++
> >  13 files changed, 445 insertions(+), 15 deletions(-)
> >  create mode 100644 arch/riscv/include/asm/patch.h
> >  create mode 100644 arch/riscv/include/asm/set_memory.h
> >  create mode 100644 arch/riscv/kernel/patch.c
> >  create mode 100644 arch/riscv/mm/pageattr.c
> >
> > --
> > 2.25.1
> >
>
>
> --
> Masami Hiramatsu <mhiramat@kernel.org>