From: Greg KH <greg@kroah.com>
To: Phong Tran <tranmanphong@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
catalin.marinas@arm.com, will@kernel.org,
alexios.zavras@intel.com, tglx@linutronix.de,
akpm@linux-foundation.org, steven.price@arm.com,
steve.capper@arm.com, broonie@kernel.org, keescook@chromium.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com
Subject: Re: [PATCH] arm64: add check_wx_pages debugfs for CHECK_WX
Date: Mon, 9 Mar 2020 13:21:38 +0100 [thread overview]
Message-ID: <20200309122138.GA206943@kroah.com> (raw)
In-Reply-To: <20200309121713.GA26309@lakrids.cambridge.arm.com>
On Mon, Mar 09, 2020 at 12:17:14PM +0000, Mark Rutland wrote:
> On Sat, Mar 07, 2020 at 04:39:26PM +0700, Phong Tran wrote:
> > follow the suggestion from
> > https://github.com/KSPP/linux/issues/35
>
> That says:
>
> | This should be implemented for all architectures
>
> ... so surely this should be in generic code, rahter than being
> arm64-specific?
>
> Thanks,
> Mark.
>
> >
> > Signed-off-by: Phong Tran <tranmanphong@gmail.com>
> > ---
> > arch/arm64/Kconfig.debug | 3 ++-
> > arch/arm64/include/asm/ptdump.h | 2 ++
> > arch/arm64/mm/dump.c | 1 +
> > arch/arm64/mm/ptdump_debugfs.c | 18 ++++++++++++++++++
> > 4 files changed, 23 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
> > index 1c906d932d6b..be552fa351e2 100644
> > --- a/arch/arm64/Kconfig.debug
> > +++ b/arch/arm64/Kconfig.debug
> > @@ -48,7 +48,8 @@ config 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's a one time check and
> > + can be checked by echo "1" to "check_wx_pages" debugfs in runtime.
> >
> > If in doubt, say "Y".
> >
> > diff --git a/arch/arm64/include/asm/ptdump.h b/arch/arm64/include/asm/ptdump.h
> > index 38187f74e089..b80d6b4fc508 100644
> > --- a/arch/arm64/include/asm/ptdump.h
> > +++ b/arch/arm64/include/asm/ptdump.h
> > @@ -24,9 +24,11 @@ struct ptdump_info {
> > void ptdump_walk(struct seq_file *s, struct ptdump_info *info);
> > #ifdef CONFIG_PTDUMP_DEBUGFS
> > void ptdump_debugfs_register(struct ptdump_info *info, const char *name);
> > +int ptdump_check_wx_init(void);
> > #else
> > static inline void ptdump_debugfs_register(struct ptdump_info *info,
> > const char *name) { }
> > +static inline int ptdump_check_wx_init(void) { return 0; }
> > #endif
> > void ptdump_check_wx(void);
> > #endif /* CONFIG_PTDUMP_CORE */
> > diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
> > index 860c00ec8bd3..60c99a047763 100644
> > --- a/arch/arm64/mm/dump.c
> > +++ b/arch/arm64/mm/dump.c
> > @@ -378,6 +378,7 @@ static int ptdump_init(void)
> > #endif
> > ptdump_initialize();
> > ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables");
> > + ptdump_check_wx_init();
> > return 0;
> > }
> > device_initcall(ptdump_init);
> > diff --git a/arch/arm64/mm/ptdump_debugfs.c b/arch/arm64/mm/ptdump_debugfs.c
> > index 1f2eae3e988b..73cddc12c3c2 100644
> > --- a/arch/arm64/mm/ptdump_debugfs.c
> > +++ b/arch/arm64/mm/ptdump_debugfs.c
> > @@ -16,3 +16,21 @@ void ptdump_debugfs_register(struct ptdump_info *info, const char *name)
> > {
> > debugfs_create_file(name, 0400, NULL, info, &ptdump_fops);
> > }
> > +
> > +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");
> > +
> > +int ptdump_check_wx_init(void)
> > +{
> > + return debugfs_create_file("check_wx_pages", 0200, NULL,
> > + NULL, &check_wx_fops) ? 0 : -ENOMEM;
Do not check the return value of this function, especially as it is
returning a pointer, not an int!
Just call the function and move on, you should not do anything different
if it returns an error or not.
thanks,
greg k-h
next prev parent reply other threads:[~2020-03-09 12:22 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-07 9:39 [PATCH] arm64: add check_wx_pages debugfs for CHECK_WX Phong Tran
2020-03-09 10:32 ` Steven Price
2020-03-09 12:17 ` Mark Rutland
2020-03-09 12:21 ` Greg KH [this message]
2020-03-09 16:15 ` Kees Cook
2020-03-09 16:51 ` Mark Rutland
2020-04-20 20:42 ` Will Deacon
2020-04-21 17:35 ` [PATCH v2] " Phong Tran
2020-04-22 13:32 ` Steven Price
2020-04-22 14:35 ` Mark Rutland
2020-04-22 15:26 ` Will Deacon
2020-04-22 17:11 ` Mark Rutland
2020-04-24 10:52 ` Phong Tran
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200309122138.GA206943@kroah.com \
--to=greg@kroah.com \
--cc=akpm@linux-foundation.org \
--cc=alexios.zavras@intel.com \
--cc=broonie@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=steve.capper@arm.com \
--cc=steven.price@arm.com \
--cc=tglx@linutronix.de \
--cc=tranmanphong@gmail.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).