From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: jeyu@kernel.org, linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
keescook@chromium.org, Miroslav Benes <mbenes@suse.cz>
Subject: Re: [PATCH] module: Harden STRICT_MODULE_RWX
Date: Fri, 3 Apr 2020 19:08:50 +0200 [thread overview]
Message-ID: <20200403170850.GA20730@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200403165631.hrxxm3pnzqa4vxln@treble>
On Fri, Apr 03, 2020 at 11:56:31AM -0500, Josh Poimboeuf wrote:
> On Fri, Apr 03, 2020 at 06:37:16PM +0200, Peter Zijlstra wrote:
> >
> > We're very close to enforcing W^X memory, refuse to load modules that
> > violate this principle per construction.
> >
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > Cc: Jessica Yu <jeyu@kernel.org>
> > Cc: Kees Cook <keescook@chromium.org>
> > ---
> > kernel/module.c | 24 ++++++++++++++++++++++++
> > 1 file changed, 24 insertions(+)
> >
> > --- a/kernel/module.c
> > +++ b/kernel/module.c
> > @@ -2044,9 +2044,28 @@ static void module_enable_x(const struct
> > frob_text(&mod->core_layout, set_memory_x);
> > frob_text(&mod->init_layout, set_memory_x);
> > }
> > +
> > +static int module_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
> > + char *secstrings, struct module *mod)
>
> A verb would be nice: "module_enforce_rwx_sections"?
>
> Shouldn't this be under STRICT_MODULE_RWX instead of
> ARCH_HAS_STRICT_MODULE_RWX?
>
> > +{
> > + int i;
> > +
> > + for (i = 0; i < hdr->e_shnum; i++) {
> > + if (sechdrs[i].sh_flags & (SHF_EXECINSTR|SHF_WRITE))
> > + return -ENOEXEC;
>
> I think you only want the error when both are set?
>
> if (sechdrs[i].sh_flags & (SHF_EXECINSTR|SHF_WRITE) == (SHF_EXECINSTR|SHF_WRITE))
>
Duh. yes. Let me respin.
next prev parent reply other threads:[~2020-04-03 17:09 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-03 16:37 [PATCH] module: Harden STRICT_MODULE_RWX Peter Zijlstra
2020-04-03 16:56 ` Josh Poimboeuf
2020-04-03 17:08 ` Peter Zijlstra [this message]
2020-04-06 9:55 ` Miroslav Benes
2020-04-06 10:46 ` Jessica Yu
2020-04-06 11:27 ` Peter Zijlstra
2020-04-06 12:53 ` Jessica Yu
2020-04-06 14:11 ` Peter Zijlstra
2020-04-07 7:43 ` Miroslav Benes
2020-04-09 16:55 ` Miroslav Benes
2020-04-10 9:04 ` Jessica Yu
2020-04-03 16:59 ` Josh Poimboeuf
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=20200403170850.GA20730@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=jeyu@kernel.org \
--cc=jpoimboe@redhat.com \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mbenes@suse.cz \
--cc=tglx@linutronix.de \
/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).