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From: Michael Ellerman <mpe@ellerman.id.au>
To: Jordan Niethe <jniethe5@gmail.com>
Cc: ajd@linux.ibm.com, cmr@codefail.de,
	Nicholas Piggin <npiggin@gmail.com>,
	naveen.n.rao@linux.ibm.com,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Daniel Axtens <dja@axtens.net>
Subject: Re: [PATCH v10 05/10] powerpc/bpf: Write protect JIT code
Date: Wed, 21 Apr 2021 16:51:30 +1000	[thread overview]
Message-ID: <87wnswb05p.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <CACzsE9oERR+KKBe=+eQU1skwTOpDAmi8=_rOMAwM8+LtfBqRKA@mail.gmail.com>

Jordan Niethe <jniethe5@gmail.com> writes:
> On Wed, Mar 31, 2021 at 9:37 PM Michael Ellerman <mpe@ellerman.id.au> wrote:
>>
>> Jordan Niethe <jniethe5@gmail.com> writes:
>>
>> > Once CONFIG_STRICT_MODULE_RWX is enabled there will be no need to
>> > override bpf_jit_free() because it is now possible to set images
>> > read-only. So use the default implementation.
>> >
>> > Also add the necessary call to bpf_jit_binary_lock_ro() which will
>> > remove write protection and add exec protection to the JIT image after
>> > it has finished being written.
>> >
>> > Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
>> > ---
>> > v10: New to series
>> > ---
>> >  arch/powerpc/net/bpf_jit_comp.c   | 5 ++++-
>> >  arch/powerpc/net/bpf_jit_comp64.c | 4 ++++
>> >  2 files changed, 8 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
>> > index e809cb5a1631..8015e4a7d2d4 100644
>> > --- a/arch/powerpc/net/bpf_jit_comp.c
>> > +++ b/arch/powerpc/net/bpf_jit_comp.c
>> > @@ -659,12 +659,15 @@ void bpf_jit_compile(struct bpf_prog *fp)
>> >               bpf_jit_dump(flen, proglen, pass, code_base);
>> >
>> >       bpf_flush_icache(code_base, code_base + (proglen/4));
>> > -
>> >  #ifdef CONFIG_PPC64
>> >       /* Function descriptor nastiness: Address + TOC */
>> >       ((u64 *)image)[0] = (u64)code_base;
>> >       ((u64 *)image)[1] = local_paca->kernel_toc;
>> >  #endif
>> > +     if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) {
>> > +             set_memory_ro((unsigned long)image, alloclen >> PAGE_SHIFT);
>> > +             set_memory_x((unsigned long)image, alloclen >> PAGE_SHIFT);
>> > +     }
>>
>> You don't need to check the ifdef in a caller, there are stubs that
>> compile to nothing when CONFIG_ARCH_HAS_SET_MEMORY=n.

> As Christophe pointed out we could have !CONFIG_STRICT_MODULE_RWX and
> CONFIG_ARCH_HAS_SET_MEMORY which would then be wrong here.
> Probably we could make CONFIG_ARCH_HAS_SET_MEMORY depend on
> CONFIG_STRICT_MODULE_RWX?

I thought it already did depend on it :)

That seems a reasonable dependency to me.

cheers

  reply	other threads:[~2021-04-21  6:52 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-30  4:51 [PATCH v10 00/10] powerpc: Further Strict RWX support Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 01/10] powerpc/mm: Implement set_memory() routines Jordan Niethe
2021-03-30  5:16   ` Christophe Leroy
2021-04-21  2:51     ` Jordan Niethe
2021-03-31 11:16   ` Michael Ellerman
2021-03-31 12:03     ` Christophe Leroy
2021-04-21  5:03     ` Jordan Niethe
2021-04-01  4:37   ` Aneesh Kumar K.V
2021-04-21  5:19     ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 02/10] powerpc/lib/code-patching: Set up Strict RWX patching earlier Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 03/10] powerpc: Always define MODULES_{VADDR,END} Jordan Niethe
2021-03-30  5:00   ` Christophe Leroy
2021-04-01 13:36   ` Christophe Leroy
2021-04-21  2:46     ` Jordan Niethe
2021-04-21  5:14       ` Christophe Leroy
2021-04-21  5:22         ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 04/10] powerpc/kprobes: Mark newly allocated probes as ROX Jordan Niethe
2021-03-30  5:05   ` Christophe Leroy
2021-04-21  2:39     ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 05/10] powerpc/bpf: Write protect JIT code Jordan Niethe
2021-03-31 10:37   ` Michael Ellerman
2021-03-31 10:39     ` Christophe Leroy
2021-04-21  2:35     ` Jordan Niethe
2021-04-21  6:51       ` Michael Ellerman [this message]
2021-03-30  4:51 ` [PATCH v10 06/10] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime Jordan Niethe
2021-03-31 11:24   ` Michael Ellerman
2021-04-21  2:23     ` Jordan Niethe
2021-04-21  5:16       ` Christophe Leroy
2021-03-30  4:51 ` [PATCH v10 07/10] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 08/10] powerpc/configs: Enable STRICT_MODULE_RWX in skiroot_defconfig Jordan Niethe
2021-03-30  5:27   ` Christophe Leroy
2021-04-21  2:37     ` Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 09/10] powerpc/mm: implement set_memory_attr() Jordan Niethe
2021-03-30  4:51 ` [PATCH v10 10/10] powerpc/32: use set_memory_attr() Jordan Niethe

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