* Re: [PATCH v5 3/8] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime
[not found] ` <20200226063551.65363-4-ruscur@russell.cc>
@ 2022-04-06 18:55 ` Kees Cook
2022-04-07 7:39 ` Christophe Leroy
0 siblings, 1 reply; 2+ messages in thread
From: Kees Cook @ 2022-04-06 18:55 UTC (permalink / raw)
To: Russell Currey
Cc: linuxppc-dev, ajd, linux-hardening, jniethe5, npiggin, joel, dja
*thread necromancy*
Is this patch still something folks are working on? It'd be nice to be
able to trigger this check at runtime.
-Kees
On Wed, Feb 26, 2020 at 05:35:46PM +1100, Russell Currey wrote:
> 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.
>
> Signed-off-by: Russell Currey <ruscur@russell.cc>
> ---
> 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 0b063830eea8..e37960ef68c6 100644
> --- a/arch/powerpc/Kconfig.debug
> +++ b/arch/powerpc/Kconfig.debug
> @@ -370,7 +370,7 @@ 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.
> @@ -384,7 +384,9 @@ 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 206156255247..a15e19a3b14e 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.
> @@ -413,6 +413,25 @@ 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)
> --
> 2.25.1
>
--
Kees Cook
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v5 3/8] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime
2022-04-06 18:55 ` [PATCH v5 3/8] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime Kees Cook
@ 2022-04-07 7:39 ` Christophe Leroy
0 siblings, 0 replies; 2+ messages in thread
From: Christophe Leroy @ 2022-04-07 7:39 UTC (permalink / raw)
To: Kees Cook, Russell Currey, jniethe5
Cc: ajd, npiggin, joel, dja, linuxppc-dev, linux-hardening
Le 06/04/2022 à 20:55, Kees Cook a écrit :
> *thread necromancy*
>
> Is this patch still something folks are working on? It'd be nice to be
> able to trigger this check at runtime.
The series was taken over by Jordan.
v15 of the series was accepted, but that particular patch was dropped in
v11 (see
https://patchwork.ozlabs.org/project/linuxppc-dev/cover/20210429031602.2606654-1-jniethe5@gmail.com/)
The comment was:
Some patches were dropped from this revision:
powerpc/mm/ptdump: debugfs handler for W+X checks at runtime
- Will use Christophe's generic ptdump series
Not sure what happened after that.
Christophe
>
> -Kees
>
> On Wed, Feb 26, 2020 at 05:35:46PM +1100, Russell Currey wrote:
>> 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.
>>
>> Signed-off-by: Russell Currey <ruscur@russell.cc>
>> ---
>> 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 0b063830eea8..e37960ef68c6 100644
>> --- a/arch/powerpc/Kconfig.debug
>> +++ b/arch/powerpc/Kconfig.debug
>> @@ -370,7 +370,7 @@ 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.
>> @@ -384,7 +384,9 @@ 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 206156255247..a15e19a3b14e 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.
>> @@ -413,6 +413,25 @@ 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)
>> --
>> 2.25.1
>>
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-04-06 18:55 ` [PATCH v5 3/8] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime Kees Cook
2022-04-07 7:39 ` Christophe Leroy
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