Date: Thu, 31 Oct 2019 11:09:21 +1100 From: Russell Currey <ruscur@...sell.cc> To: Christophe Leroy <christophe.leroy@....fr>, linuxppc-dev@...ts.ozlabs.org Cc: joel@....id.au, mpe@...erman.id.au, ajd@...ux.ibm.com, dja@...ens.net, npiggin@...il.com, kernel-hardening@...ts.openwall.com Subject: Re: [PATCH v5 0/5] Implement STRICT_MODULE_RWX for powerpc On Wed, 2019-10-30 at 09:58 +0100, Christophe Leroy wrote: > > Le 30/10/2019 à 08:31, Russell Currey a écrit : > > v4 cover letter: > > https://lists.ozlabs.org/pipermail/linuxppc-dev/2019-October/198268.html > > v3 cover letter: > > https://lists.ozlabs.org/pipermail/linuxppc-dev/2019-October/198023.html > > > > Changes since v4: > > [1/5]: Addressed review comments from Michael Ellerman > > (thanks!) > > [4/5]: make ARCH_HAS_STRICT_MODULE_RWX depend on > > ARCH_HAS_STRICT_KERNEL_RWX to simplify things and avoid > > STRICT_MODULE_RWX being *on by default* in cases where > > STRICT_KERNEL_RWX is *unavailable* > > [5/5]: split skiroot_defconfig changes out into its own patch > > > > The whole Kconfig situation is really weird and confusing, I > > believe the > > correct resolution is to change arch/Kconfig but the consequences > > are so > > minor that I don't think it's worth it, especially given that I > > expect > > powerpc to have mandatory strict RWX Soon(tm). > > I'm not such strict RWX can be made mandatory due to the impact it > has > on some subarches: > - On the 8xx, unless all areas are 8Mbytes aligned, there is a > significant overhead on TLB misses. And Aligning everthing to 8M is > a > waste of RAM which is not acceptable on systems having very few RAM. > - On hash book3s32, we are able to map the kernel BATs. With a few > alignment constraints, we are able to provide STRICT_KERNEL_RWX. But > we > are unable to provide exec protection on page granularity. Only on > 256Mbytes segments. So for modules, we have to have the vmspace X. It > is > also not possible to have a kernel area RO. Only user areas can be > made RO. > Yes, sorry, this was thoughtless from me, since in my mind I was just thinking about the platforms I primarily work on (book3s64). > Christophe > > > Russell Currey (5): > > powerpc/mm: Implement set_memory() routines > > powerpc/kprobes: Mark newly allocated probes as RO > > powerpc/mm/ptdump: debugfs handler for W+X checks at runtime > > powerpc: Set ARCH_HAS_STRICT_MODULE_RWX > > powerpc/configs: Enable STRICT_MODULE_RWX in skiroot_defconfig > > > > arch/powerpc/Kconfig | 2 + > > arch/powerpc/Kconfig.debug | 6 +- > > arch/powerpc/configs/skiroot_defconfig | 1 + > > arch/powerpc/include/asm/set_memory.h | 32 +++++++++++ > > arch/powerpc/kernel/kprobes.c | 3 + > > arch/powerpc/mm/Makefile | 1 + > > arch/powerpc/mm/pageattr.c | 77 > > ++++++++++++++++++++++++++ > > arch/powerpc/mm/ptdump/ptdump.c | 21 ++++++- > > 8 files changed, 140 insertions(+), 3 deletions(-) > > create mode 100644 arch/powerpc/include/asm/set_memory.h > > create mode 100644 arch/powerpc/mm/pageattr.c > >
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.