From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
David Brown <david.brown@linaro.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 v5 5/7] lkdtm: verify that __ro_after_init works correctly
Date: Wed, 17 Feb 2016 14:41:16 -0800 [thread overview]
Message-ID: <1455748879-21872-6-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1455748879-21872-1-git-send-email-keescook@chromium.org>
The new __ro_after_init section should be writable before init, but
not after. Validate that it gets updated at init and can't be written
to afterwards.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/misc/lkdtm.c | 29 ++++++++++++++++++++++++++---
1 file changed, 26 insertions(+), 3 deletions(-)
diff --git a/drivers/misc/lkdtm.c b/drivers/misc/lkdtm.c
index 5c1351b19029..a77799d227ee 100644
--- a/drivers/misc/lkdtm.c
+++ b/drivers/misc/lkdtm.c
@@ -103,6 +103,7 @@ enum ctype {
CT_EXEC_USERSPACE,
CT_ACCESS_USERSPACE,
CT_WRITE_RO,
+ CT_WRITE_RO_AFTER_INIT,
CT_WRITE_KERN,
};
@@ -140,6 +141,7 @@ static char* cp_type[] = {
"EXEC_USERSPACE",
"ACCESS_USERSPACE",
"WRITE_RO",
+ "WRITE_RO_AFTER_INIT",
"WRITE_KERN",
};
@@ -162,6 +164,7 @@ static DEFINE_SPINLOCK(lock_me_up);
static u8 data_area[EXEC_SIZE];
static const unsigned long rodata = 0xAA55AA55;
+static unsigned long ro_after_init __ro_after_init = 0x55AA5500;
module_param(recur_count, int, 0644);
MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
@@ -503,11 +506,28 @@ static void lkdtm_do_action(enum ctype which)
break;
}
case CT_WRITE_RO: {
- unsigned long *ptr;
+ /* Explicitly cast away "const" for the test. */
+ unsigned long *ptr = (unsigned long *)&rodata;
- ptr = (unsigned long *)&rodata;
+ pr_info("attempting bad rodata write at %p\n", ptr);
+ *ptr ^= 0xabcd1234;
- pr_info("attempting bad write at %p\n", ptr);
+ break;
+ }
+ case CT_WRITE_RO_AFTER_INIT: {
+ unsigned long *ptr = &ro_after_init;
+
+ /*
+ * Verify we were written to during init. Since an Oops
+ * is considered a "success", a failure is to just skip the
+ * real test.
+ */
+ if ((*ptr & 0xAA) != 0xAA) {
+ pr_info("%p was NOT written during init!?\n", ptr);
+ break;
+ }
+
+ pr_info("attempting bad ro_after_init write at %p\n", ptr);
*ptr ^= 0xabcd1234;
break;
@@ -817,6 +837,9 @@ static int __init lkdtm_module_init(void)
int n_debugfs_entries = 1; /* Assume only the direct entry */
int i;
+ /* Make sure we can write to __ro_after_init values during __init */
+ ro_after_init |= 0xAA;
+
/* Register debugfs interface */
lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
if (!lkdtm_debugfs_root) {
--
2.6.3
next prev parent reply other threads:[~2016-02-17 22:41 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-17 22:41 [PATCH v5 0/7] introduce post-init read-only memory Kees Cook
2016-02-17 22:41 ` [PATCH v5 1/7] asm-generic: consolidate mark_rodata_ro() Kees Cook
2016-02-19 14:38 ` Will Deacon
2016-02-22 12:18 ` [tip:mm/readonly] asm-generic: Consolidate mark_rodata_ro() =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-22 12:18 ` =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-17 22:41 ` [PATCH v5 2/7] init: create cmdline param to disable readonly Kees Cook
2016-02-17 22:41 ` Kees Cook
2016-02-22 12:18 ` [tip:mm/readonly] mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-22 12:18 ` =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-17 22:41 ` [PATCH v5 3/7] x86: make CONFIG_DEBUG_RODATA non-optional Kees Cook
2016-02-17 22:41 ` Kees Cook
2016-02-22 12:19 ` [tip:mm/readonly] x86/mm: Always enable CONFIG_DEBUG_RODATA and remove the Kconfig option =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-22 12:19 ` =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-17 22:41 ` [PATCH v5 4/7] introduce post-init read-only memory Kees Cook
2016-02-17 22:41 ` Kees Cook
2016-02-22 12:19 ` [tip:mm/readonly] arch: Introduce " =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-22 12:19 ` =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-03-07 13:00 ` [PATCH v5 4/7] introduce " Christian Borntraeger
2016-03-08 0:16 ` Kees Cook
2016-03-08 0:16 ` Kees Cook
2016-03-08 0:23 ` Andy Lutomirski
2016-03-08 0:23 ` Andy Lutomirski
2016-02-17 22:41 ` Kees Cook [this message]
2016-02-17 22:41 ` [PATCH v5 5/7] lkdtm: verify that __ro_after_init works correctly Kees Cook
2016-02-22 12:19 ` [tip:mm/readonly] lkdtm: Verify that '__ro_after_init' " =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-22 12:19 ` =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-17 22:41 ` [PATCH v5 6/7] x86, vdso: mark vDSO read-only after init Kees Cook
2016-02-17 22:41 ` Kees Cook
2016-02-22 12:20 ` [tip:mm/readonly] x86/vdso: Mark the vDSO code " =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-22 12:20 ` =?UTF-8?B?dGlwLWJvdCBmb3IgS2VlcyBDb29rIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-17 22:41 ` [PATCH v5 7/7] ARM: vdso: Mark vDSO code as read-only Kees Cook
2016-02-17 22:41 ` Kees Cook
2016-02-22 12:20 ` [tip:mm/readonly] ARM/vdso: Mark the vDSO code read-only after init =?UTF-8?B?dGlwLWJvdCBmb3IgRGF2aWQgQnJvd24gPHRpcGJvdEB6eXRvci5jb20+?=
2016-02-22 12:20 ` =?UTF-8?B?dGlwLWJvdCBmb3IgRGF2aWQgQnJvd24gPHRpcGJvdEB6eXRvci5jb20+?=
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=1455748879-21872-6-git-send-email-keescook@chromium.org \
--to=keescook@chromium.org \
--cc=arnd@arndb.de \
--cc=david.brown@linaro.org \
--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@kernel.org \
--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).