From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Jordan Niethe <jniethe5@gmail.com>, linuxppc-dev@lists.ozlabs.org
Cc: christophe.leroy@c-s.fr, ajd@linux.ibm.com,
Kees Cook <keescook@chromium.org>,
npiggin@gmail.com, naveen.n.rao@linux.ibm.com, dja@axtens.net
Subject: Re: [PATCH v9 4/8] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime
Date: Tue, 16 Mar 2021 07:47:10 +0100 [thread overview]
Message-ID: <6d91193f-1428-67f2-eaaa-59f41859af7c@csgroup.eu> (raw)
In-Reply-To: <20210316031741.1004850-4-jniethe5@gmail.com>
Le 16/03/2021 à 04:17, Jordan Niethe a écrit :
> From: Russell Currey <ruscur@russell.cc>
>
> Very rudimentary, just
>
> echo 1 > [debugfs]/check_wx_pages
>
> and check the kernel log. Useful for testing strict module RWX.
>
> Updated the Kconfig entry to reflect this.
>
> Also fixed a typo.
Why not just perform the test everytime someone dumps kernel_page_tables ?
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Russell Currey <ruscur@russell.cc>
> Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
> ---
> arch/powerpc/Kconfig.debug | 6 ++++--
> arch/powerpc/mm/ptdump/ptdump.c | 21 ++++++++++++++++++++-
> 2 files changed, 24 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
> index ae084357994e..56e99e9a30d9 100644
> --- a/arch/powerpc/Kconfig.debug
> +++ b/arch/powerpc/Kconfig.debug
> @@ -371,7 +371,7 @@ config PPC_PTDUMP
> If you are unsure, say N.
>
> config PPC_DEBUG_WX
> - bool "Warn on W+X mappings at boot"
> + bool "Warn on W+X mappings at boot & enable manual checks at runtime"
> depends on PPC_PTDUMP && STRICT_KERNEL_RWX
> help
> Generate a warning if any W+X mappings are found at boot.
> @@ -385,7 +385,9 @@ config PPC_DEBUG_WX
> of other unfixed kernel bugs easier.
>
> There is no runtime or memory usage effect of this option
> - once the kernel has booted up - it's a one time check.
> + once the kernel has booted up, it only automatically checks once.
> +
> + Enables the "check_wx_pages" debugfs entry for checking at runtime.
>
> If in doubt, say "Y".
>
> diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
> index aca354fb670b..78497d57b66b 100644
> --- a/arch/powerpc/mm/ptdump/ptdump.c
> +++ b/arch/powerpc/mm/ptdump/ptdump.c
> @@ -4,7 +4,7 @@
> *
> * This traverses the kernel pagetables and dumps the
> * information about the used sections of memory to
> - * /sys/kernel/debug/kernel_pagetables.
> + * /sys/kernel/debug/kernel_page_tables.
> *
> * Derived from the arm64 implementation:
> * Copyright (c) 2014, The Linux Foundation, Laura Abbott.
> @@ -459,6 +459,25 @@ void ptdump_check_wx(void)
> else
> pr_info("Checked W+X mappings: passed, no W+X pages found\n");
> }
> +
> +static int check_wx_debugfs_set(void *data, u64 val)
> +{
> + if (val != 1ULL)
> + return -EINVAL;
> +
> + ptdump_check_wx();
> +
> + return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(check_wx_fops, NULL, check_wx_debugfs_set, "%llu\n");
> +
> +static int ptdump_check_wx_init(void)
> +{
> + return debugfs_create_file("check_wx_pages", 0200, NULL,
> + NULL, &check_wx_fops) ? 0 : -ENOMEM;
> +}
> +device_initcall(ptdump_check_wx_init);
> #endif
>
> static int ptdump_init(void)
>
next prev parent reply other threads:[~2021-03-16 6:47 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 3:17 [PATCH v9 1/8] powerpc/mm: Implement set_memory() routines Jordan Niethe
2021-03-16 3:17 ` [PATCH v9 2/8] powerpc/lib/code-patching: Set up Strict RWX patching earlier Jordan Niethe
2021-03-16 3:36 ` Russell Currey
2021-03-16 6:32 ` Christophe Leroy
2021-03-17 0:38 ` Jordan Niethe
2021-03-17 12:04 ` Michael Ellerman
2021-03-16 3:17 ` [PATCH v9 3/8] powerpc/kprobes: Mark newly allocated probes as RO Jordan Niethe
2021-03-16 6:44 ` Christophe Leroy
2021-03-17 0:50 ` Jordan Niethe
2021-03-17 0:52 ` Jordan Niethe
2021-03-17 6:12 ` Christophe Leroy
2021-03-18 2:42 ` Jordan Niethe
2021-03-16 3:17 ` [PATCH v9 4/8] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime Jordan Niethe
2021-03-16 6:47 ` Christophe Leroy [this message]
2021-03-16 3:17 ` [PATCH v9 5/8] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX Jordan Niethe
2021-03-16 6:51 ` Christophe Leroy
2021-03-17 2:15 ` Jordan Niethe
2021-03-17 5:43 ` Christophe Leroy
2021-03-16 3:17 ` [PATCH v9 6/8] powerpc/configs: Enable STRICT_MODULE_RWX in skiroot_defconfig Jordan Niethe
2021-03-16 3:17 ` [PATCH v9 7/8] powerpc/mm: implement set_memory_attr() Jordan Niethe
2021-03-16 7:25 ` Christophe Leroy
2021-03-17 0:54 ` Jordan Niethe
2021-03-16 3:17 ` [PATCH v9 8/8] powerpc/32: use set_memory_attr() Jordan Niethe
2021-03-19 1:19 ` [PATCH v9 1/8] powerpc/mm: Implement set_memory() routines Michael Ellerman
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