@@ -155,6 +155,9 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(ACCESS_USERSPACE),
CRASHTYPE(WRITE_RO),
CRASHTYPE(WRITE_RO_AFTER_INIT),
+#ifdef CONFIG_PRMEM
+ CRASHTYPE(WRITE_WR_AFTER_INIT),
+#endif
CRASHTYPE(WRITE_KERN),
CRASHTYPE(REFCOUNT_INC_OVERFLOW),
CRASHTYPE(REFCOUNT_ADD_OVERFLOW),
@@ -38,6 +38,9 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void);
void __init lkdtm_perms_init(void);
void lkdtm_WRITE_RO(void);
void lkdtm_WRITE_RO_AFTER_INIT(void);
+#ifdef CONFIG_PRMEM
+void lkdtm_WRITE_WR_AFTER_INIT(void);
+#endif
void lkdtm_WRITE_KERN(void);
void lkdtm_EXEC_DATA(void);
void lkdtm_EXEC_STACK(void);
@@ -9,6 +9,7 @@
#include <linux/vmalloc.h>
#include <linux/mman.h>
#include <linux/uaccess.h>
+#include <linux/prmem.h>
#include <asm/cacheflush.h>
/* Whether or not to fill the target memory area with do_nothing(). */
@@ -27,6 +28,10 @@ static const unsigned long rodata = 0xAA55AA55;
/* This is marked __ro_after_init, so it should ultimately be .rodata. */
static unsigned long ro_after_init __ro_after_init = 0x55AA5500;
+/* This is marked __wr_after_init, so it should be in .rodata. */
+static
+unsigned long wr_after_init __wr_after_init = 0x55AA5500;
+
/*
* This just returns to the caller. It is designed to be copied into
* non-executable memory regions.
@@ -104,6 +109,28 @@ void lkdtm_WRITE_RO_AFTER_INIT(void)
*ptr ^= 0xabcd1234;
}
+#ifdef CONFIG_PRMEM
+
+void lkdtm_WRITE_WR_AFTER_INIT(void)
+{
+ unsigned long *ptr = &wr_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);
+ return;
+ }
+
+ pr_info("attempting bad wr_after_init write at %p\n", ptr);
+ *ptr ^= 0xabcd1234;
+}
+
+#endif
+
void lkdtm_WRITE_KERN(void)
{
size_t size;
@@ -200,4 +227,6 @@ void __init lkdtm_perms_init(void)
/* Make sure we can write to __ro_after_init values during __init */
ro_after_init |= 0xAA;
+ /* Make sure we can write to __wr_after_init during __init */
+ wr_after_init |= 0xAA;
}
Verify that trying to modify a variable with the __wr_after_init attribute will cause a crash. Signed-off-by: Igor Stoppa <igor.stoppa@huawei.com> CC: Andy Lutomirski <luto@amacapital.net> CC: Nadav Amit <nadav.amit@gmail.com> CC: Matthew Wilcox <willy@infradead.org> CC: Peter Zijlstra <peterz@infradead.org> CC: Kees Cook <keescook@chromium.org> CC: Dave Hansen <dave.hansen@linux.intel.com> CC: Mimi Zohar <zohar@linux.vnet.ibm.com> CC: Thiago Jung Bauermann <bauerman@linux.ibm.com> CC: Ahmed Soliman <ahmedsoliman@mena.vt.edu> CC: linux-integrity@vger.kernel.org CC: kernel-hardening@lists.openwall.com CC: linux-mm@kvack.org CC: linux-kernel@vger.kernel.org --- drivers/misc/lkdtm/core.c | 3 +++ drivers/misc/lkdtm/lkdtm.h | 3 +++ drivers/misc/lkdtm/perms.c | 29 +++++++++++++++++++++++++++++ 3 files changed, 35 insertions(+)