From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Andrew Morton <akpm@linux-foundation.org>,
"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
Helge Deller <deller@gmx.de>, Arnd Bergmann <arnd@arndb.de>,
Kees Cook <keescook@chromium.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-arch@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v4 12/13] lkdtm: Fix execute_[user]_location()
Date: Tue, 15 Feb 2022 13:41:07 +0100 [thread overview]
Message-ID: <4055839683d8d643cd99be121f4767c7c611b970.1644928018.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <cover.1644928018.git.christophe.leroy@csgroup.eu>
execute_location() and execute_user_location() intent
to copy do_nothing() text and execute it at a new location.
However, at the time being it doesn't copy do_nothing() function
but do_nothing() function descriptor which still points to the
original text. So at the end it still executes do_nothing() at
its original location allthough using a copied function descriptor.
So, fix that by really copying do_nothing() text and build a new
function descriptor by copying do_nothing() function descriptor and
updating the target address with the new location.
Also fix the displayed addresses by dereferencing do_nothing()
function descriptor.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Kees Cook <keescook@chromium.org>
---
drivers/misc/lkdtm/perms.c | 37 ++++++++++++++++++++++++++++---------
1 file changed, 28 insertions(+), 9 deletions(-)
diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c
index 035fcca441f0..1cf24c4a79e9 100644
--- a/drivers/misc/lkdtm/perms.c
+++ b/drivers/misc/lkdtm/perms.c
@@ -44,19 +44,34 @@ static noinline void do_overwritten(void)
return;
}
+static void *setup_function_descriptor(func_desc_t *fdesc, void *dst)
+{
+ if (!have_function_descriptors())
+ return dst;
+
+ memcpy(fdesc, do_nothing, sizeof(*fdesc));
+ fdesc->addr = (unsigned long)dst;
+ barrier();
+
+ return fdesc;
+}
+
static noinline void execute_location(void *dst, bool write)
{
- void (*func)(void) = dst;
+ void (*func)(void);
+ func_desc_t fdesc;
+ void *do_nothing_text = dereference_function_descriptor(do_nothing);
- pr_info("attempting ok execution at %px\n", do_nothing);
+ pr_info("attempting ok execution at %px\n", do_nothing_text);
do_nothing();
if (write == CODE_WRITE) {
- memcpy(dst, do_nothing, EXEC_SIZE);
+ memcpy(dst, do_nothing_text, EXEC_SIZE);
flush_icache_range((unsigned long)dst,
(unsigned long)dst + EXEC_SIZE);
}
- pr_info("attempting bad execution at %px\n", func);
+ pr_info("attempting bad execution at %px\n", dst);
+ func = setup_function_descriptor(&fdesc, dst);
func();
pr_err("FAIL: func returned\n");
}
@@ -66,16 +81,19 @@ static void execute_user_location(void *dst)
int copied;
/* Intentionally crossing kernel/user memory boundary. */
- void (*func)(void) = dst;
+ void (*func)(void);
+ func_desc_t fdesc;
+ void *do_nothing_text = dereference_function_descriptor(do_nothing);
- pr_info("attempting ok execution at %px\n", do_nothing);
+ pr_info("attempting ok execution at %px\n", do_nothing_text);
do_nothing();
- copied = access_process_vm(current, (unsigned long)dst, do_nothing,
+ copied = access_process_vm(current, (unsigned long)dst, do_nothing_text,
EXEC_SIZE, FOLL_WRITE);
if (copied < EXEC_SIZE)
return;
- pr_info("attempting bad execution at %px\n", func);
+ pr_info("attempting bad execution at %px\n", dst);
+ func = setup_function_descriptor(&fdesc, dst);
func();
pr_err("FAIL: func returned\n");
}
@@ -153,7 +171,8 @@ void lkdtm_EXEC_VMALLOC(void)
void lkdtm_EXEC_RODATA(void)
{
- execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS);
+ execute_location(dereference_function_descriptor(lkdtm_rodata_do_nothing),
+ CODE_AS_IS);
}
void lkdtm_EXEC_USERSPACE(void)
--
2.34.1
next prev parent reply other threads:[~2022-02-15 12:43 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-15 12:40 [PATCH v4 00/13] Fix LKDTM for PPC64/IA64/PARISC v4 Christophe Leroy
2022-02-15 12:40 ` [PATCH v4 01/13] powerpc: Fix 'sparse' checking on PPC64le Christophe Leroy
2022-02-15 16:06 ` Kees Cook
2022-02-15 12:40 ` [PATCH v4 02/13] powerpc: Move and rename func_descr_t Christophe Leroy
2022-02-15 12:40 ` [PATCH v4 03/13] powerpc: Use 'struct func_desc' instead of 'struct ppc64_opd_entry' Christophe Leroy
2022-02-15 12:40 ` [PATCH v4 04/13] powerpc: Remove " Christophe Leroy
2022-02-15 12:41 ` [PATCH v4 05/13] powerpc: Prepare func_desc_t for refactorisation Christophe Leroy
2022-02-15 12:41 ` [PATCH v4 06/13] ia64: Rename 'ip' to 'addr' in 'struct fdesc' Christophe Leroy
2022-02-15 12:41 ` [PATCH v4 07/13] asm-generic: Define CONFIG_HAVE_FUNCTION_DESCRIPTORS Christophe Leroy
2022-02-15 12:41 ` [PATCH v4 08/13] asm-generic: Define 'func_desc_t' to commonly describe function descriptors Christophe Leroy
2022-02-15 12:41 ` [PATCH v4 09/13] asm-generic: Refactor dereference_[kernel]_function_descriptor() Christophe Leroy
2022-02-15 12:41 ` [PATCH v4 10/13] lkdtm: Force do_nothing() out of line Christophe Leroy
2022-02-15 12:41 ` [PATCH v4 11/13] lkdtm: Really write into kernel text in WRITE_KERN Christophe Leroy
2022-02-15 12:41 ` Christophe Leroy [this message]
2022-02-15 12:41 ` [PATCH v4 13/13] lkdtm: Add a test for function descriptors protection Christophe Leroy
2022-02-15 16:07 ` [PATCH v4 00/13] Fix LKDTM for PPC64/IA64/PARISC v4 Kees Cook
2022-02-16 12:22 ` Michael Ellerman
2022-02-16 16:20 ` Kees Cook
2022-02-16 13:26 ` Helge Deller
2022-02-16 12:25 ` John Paul Adrian Glaubitz
2022-02-21 20:06 ` John Paul Adrian Glaubitz
2022-03-08 12:07 ` Michael Ellerman
2022-03-09 1:37 ` Michael Ellerman
2022-03-09 16:30 ` Kees Cook
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