From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>,
Andy Lutomirski <luto@amacapital.net>,
"H. Peter Anvin" <hpa@zytor.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Mathias Krause <minipli@googlemail.com>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, Arnd Bergmann <arnd@arndb.de>,
PaX Team <pageexec@freemail.hu>, Emese Revfy <re.emese@gmail.com>,
kernel-hardening@lists.openwall.com,
linux-kernel@vger.kernel.org,
linux-arch <linux-arch@vger.kernel.org>
Subject: [PATCH v4 8/8] x86, vdso: mark vDSO read-only after init
Date: Tue, 19 Jan 2016 10:08:42 -0800 [thread overview]
Message-ID: <1453226922-16831-9-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1453226922-16831-1-git-send-email-keescook@chromium.org>
The vDSO does not need to be writable after __init, so mark it as
__ro_after_init. The result kills the exploit method of writing to the
vDSO from kernel space resulting in userspace executing the modified code,
as shown here to bypass SMEP restrictions: http://itszn.com/blog/?p=21
The memory map (with added vDSO address reporting) shows the vDSO moving
into read-only memory:
Before:
[ 0.143067] vDSO @ ffffffff82004000
[ 0.143551] vDSO @ ffffffff82006000
---[ High Kernel Mapping ]---
0xffffffff80000000-0xffffffff81000000 16M pmd
0xffffffff81000000-0xffffffff81800000 8M ro PSE GLB x pmd
0xffffffff81800000-0xffffffff819f3000 1996K ro GLB x pte
0xffffffff819f3000-0xffffffff81a00000 52K ro NX pte
0xffffffff81a00000-0xffffffff81e00000 4M ro PSE GLB NX pmd
0xffffffff81e00000-0xffffffff81e05000 20K ro GLB NX pte
0xffffffff81e05000-0xffffffff82000000 2028K ro NX pte
0xffffffff82000000-0xffffffff8214f000 1340K RW GLB NX pte
0xffffffff8214f000-0xffffffff82281000 1224K RW NX pte
0xffffffff82281000-0xffffffff82400000 1532K RW GLB NX pte
0xffffffff82400000-0xffffffff83200000 14M RW PSE GLB NX pmd
0xffffffff83200000-0xffffffffc0000000 974M pmd
After:
[ 0.145062] vDSO @ ffffffff81da1000
[ 0.146057] vDSO @ ffffffff81da4000
---[ High Kernel Mapping ]---
0xffffffff80000000-0xffffffff81000000 16M pmd
0xffffffff81000000-0xffffffff81800000 8M ro PSE GLB x pmd
0xffffffff81800000-0xffffffff819f3000 1996K ro GLB x pte
0xffffffff819f3000-0xffffffff81a00000 52K ro NX pte
0xffffffff81a00000-0xffffffff81e00000 4M ro PSE GLB NX pmd
0xffffffff81e00000-0xffffffff81e0b000 44K ro GLB NX pte
0xffffffff81e0b000-0xffffffff82000000 2004K ro NX pte
0xffffffff82000000-0xffffffff8214c000 1328K RW GLB NX pte
0xffffffff8214c000-0xffffffff8227e000 1224K RW NX pte
0xffffffff8227e000-0xffffffff82400000 1544K RW GLB NX pte
0xffffffff82400000-0xffffffff83200000 14M RW PSE GLB NX pmd
0xffffffff83200000-0xffffffffc0000000 974M pmd
Based on work by PaX Team and Brad Spengler.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/entry/vdso/vdso2c.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/entry/vdso/vdso2c.h b/arch/x86/entry/vdso/vdso2c.h
index 0224987556ce..eb93a3137ed2 100644
--- a/arch/x86/entry/vdso/vdso2c.h
+++ b/arch/x86/entry/vdso/vdso2c.h
@@ -140,7 +140,7 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
fprintf(outfile, "#include <asm/vdso.h>\n");
fprintf(outfile, "\n");
fprintf(outfile,
- "static unsigned char raw_data[%lu] __page_aligned_data = {",
+ "static unsigned char raw_data[%lu] __ro_after_init __aligned(PAGE_SIZE) = {",
mapping_size);
for (j = 0; j < stripped_len; j++) {
if (j % 10 == 0)
@@ -150,7 +150,7 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
}
fprintf(outfile, "\n};\n\n");
- fprintf(outfile, "static struct page *pages[%lu];\n\n",
+ fprintf(outfile, "static struct page *pages[%lu] __ro_after_init;\n\n",
mapping_size / 4096);
fprintf(outfile, "const struct vdso_image %s = {\n", name);
--
2.6.3
next prev parent reply other threads:[~2016-01-19 18:08 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-19 18:08 [PATCH v4 0/8] introduce post-init read-only memory Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 1/8] asm-generic: consolidate mark_rodata_ro() Kees Cook
2016-01-19 18:08 ` [PATCH v4 2/8] lib: add "on" and "off" to strtobool Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-20 2:09 ` Joe Perches
2016-01-22 23:29 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 3/8] param: convert some "on"/"off" users " Kees Cook
2016-01-27 21:11 ` David Brown
2016-01-27 21:11 ` [kernel-hardening] " David Brown
2016-01-27 21:19 ` Kees Cook
2016-01-28 0:09 ` [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional David Brown
2016-01-28 0:09 ` David Brown
2016-01-28 0:14 ` Kees Cook
2016-01-28 0:14 ` Kees Cook
2016-01-28 8:20 ` Ard Biesheuvel
2016-01-28 8:20 ` Ard Biesheuvel
2016-01-28 11:06 ` Mark Rutland
2016-01-28 11:06 ` Mark Rutland
2016-01-28 14:06 ` Kees Cook
2016-01-28 14:06 ` Kees Cook
2016-01-28 14:59 ` Mark Rutland
2016-01-28 14:59 ` Mark Rutland
2016-01-28 15:17 ` Kees Cook
2016-01-28 15:17 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 4/8] init: create cmdline param to disable readonly Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 5/8] x86: make CONFIG_DEBUG_RODATA non-optional Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 6/8] introduce post-init read-only memory Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 7/8] lkdtm: verify that __ro_after_init works correctly Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-19 18:08 ` Kees Cook [this message]
2016-01-19 18:08 ` [PATCH v4 8/8] x86, vdso: mark vDSO read-only after init Kees Cook
2016-01-19 19:09 ` Andy Lutomirski
2016-01-20 2:51 ` H. Peter Anvin
2016-01-20 2:51 ` H. Peter Anvin
2016-01-20 2:56 ` Andy Lutomirski
2016-01-22 17:19 ` [PATCH v4 0/8] introduce post-init read-only memory David Brown
2016-01-22 17:19 ` [kernel-hardening] " David Brown
2016-01-22 19:16 ` Laura Abbott
2016-01-22 19:16 ` Laura Abbott
2016-01-22 19:57 ` Kees Cook
2016-01-23 9:49 ` Geert Uytterhoeven
2016-02-16 21:36 ` [PATCH] ARM: vdso: Mark vDSO code as read-only David Brown
2016-02-16 21:52 ` Kees Cook
2016-02-17 5:20 ` David Brown
2016-02-17 23:00 ` Kees Cook
2016-02-17 23:43 ` David Brown
2016-02-17 23:43 ` David Brown
2016-02-17 23:48 ` Kees Cook
2016-02-18 10:46 ` PaX Team
2016-02-18 10:46 ` PaX Team
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=1453226922-16831-9-git-send-email-keescook@chromium.org \
--to=keescook@chromium.org \
--cc=arnd@arndb.de \
--cc=hpa@zytor.com \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=mingo@redhat.com \
--cc=minipli@googlemail.com \
--cc=mpe@ellerman.id.au \
--cc=pageexec@freemail.hu \
--cc=re.emese@gmail.com \
--cc=tglx@linutronix.de \
--cc=x86@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).