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Message-Id: <20170607211653.14536-3-tycho@docker.com>
Date: Wed, 7 Jun 2017 15:16:52 -0600
From: Tycho Andersen <tycho@...ker.com>
To: linux-mm@...ck.org
Cc: Juerg Haefliger <juergh@...il.com>,
kernel-hardening@...ts.openwall.com,
Juerg Haefliger <juerg.haefliger@....com>,
Tycho Andersen <tycho@...ker.com>
Subject: [RFC v4 2/3] lkdtm: Add tests for XPFO
From: Juerg Haefliger <juerg.haefliger@....com>
Signed-off-by: Juerg Haefliger <juerg.haefliger@....com>
minor fixups for 5-level paging, whitespace
Signed-off-by: Tycho Andersen <tycho@...ker.com>
---
drivers/misc/Makefile | 1 +
drivers/misc/lkdtm.h | 3 ++
drivers/misc/lkdtm_core.c | 1 +
drivers/misc/lkdtm_xpfo.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 110 insertions(+)
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 81ef3e67acc9..e0b5065478be 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -61,6 +61,7 @@ lkdtm-$(CONFIG_LKDTM) += lkdtm_heap.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_perms.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_rodata_objcopy.o
lkdtm-$(CONFIG_LKDTM) += lkdtm_usercopy.o
+lkdtm-$(CONFIG_LKDTM) += lkdtm_xpfo.o
KCOV_INSTRUMENT_lkdtm_rodata.o := n
diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
index 3b4976396ec4..ed9c3131bf41 100644
--- a/drivers/misc/lkdtm.h
+++ b/drivers/misc/lkdtm.h
@@ -64,4 +64,7 @@ void lkdtm_USERCOPY_STACK_FRAME_FROM(void);
void lkdtm_USERCOPY_STACK_BEYOND(void);
void lkdtm_USERCOPY_KERNEL(void);
+/* lkdtm_xpfo.c */
+void lkdtm_XPFO_READ_USER(void);
+
#endif
diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index 42d2b8e31e6b..4f3b60bb2d31 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -235,6 +235,7 @@ struct crashtype crashtypes[] = {
CRASHTYPE(USERCOPY_STACK_FRAME_FROM),
CRASHTYPE(USERCOPY_STACK_BEYOND),
CRASHTYPE(USERCOPY_KERNEL),
+ CRASHTYPE(XPFO_READ_USER),
};
diff --git a/drivers/misc/lkdtm_xpfo.c b/drivers/misc/lkdtm_xpfo.c
new file mode 100644
index 000000000000..540a2539a88b
--- /dev/null
+++ b/drivers/misc/lkdtm_xpfo.c
@@ -0,0 +1,105 @@
+/*
+ * This is for all the tests related to XPFO (eXclusive Page Frame Ownership).
+ */
+
+#include "lkdtm.h"
+
+#include <linux/mman.h>
+#include <linux/uaccess.h>
+
+/* This is hacky... */
+#ifdef CONFIG_ARM64
+#define pud_large(pud) (pud_sect(pud))
+#define pmd_large(pmd) (pmd_sect(pmd))
+#define PUD_PAGE_MASK PUD_MASK
+#define PMD_PAGE_MASK PMD_MASK
+#endif
+
+static phys_addr_t user_virt_to_phys(unsigned long addr)
+{
+ phys_addr_t phys_addr;
+ unsigned long offset;
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+ p4d_t *p4d;
+
+ pgd = pgd_offset(current->mm, addr);
+ if (pgd_none(*pgd))
+ return 0;
+
+ p4d = p4d_offset(pgd, addr);
+ if (p4d_none(*p4d))
+ return 0;
+
+ pud = pud_offset(p4d, addr);
+ if (pud_none(*pud))
+ return 0;
+
+ if (pud_large(*pud) || !pud_present(*pud)) {
+ phys_addr = (unsigned long)pud_pfn(*pud) << PAGE_SHIFT;
+ offset = addr & ~PUD_PAGE_MASK;
+ goto out;
+ }
+
+ pmd = pmd_offset(pud, addr);
+ if (pmd_none(*pmd))
+ return 0;
+
+ if (pmd_large(*pmd) || !pmd_present(*pmd)) {
+ phys_addr = (unsigned long)pmd_pfn(*pmd) << PAGE_SHIFT;
+ offset = addr & ~PMD_PAGE_MASK;
+ goto out;
+ }
+
+ pte = pte_offset_kernel(pmd, addr);
+ phys_addr = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT;
+ offset = addr & ~PAGE_MASK;
+
+out:
+ return (phys_addr_t)(phys_addr | offset);
+}
+
+/* Read from userspace via the kernel's linear map */
+void lkdtm_XPFO_READ_USER(void)
+{
+ unsigned long user_addr, user_data = 0xdeadbeef;
+ phys_addr_t phys_addr;
+ void *virt_addr;
+
+ user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+ PROT_READ | PROT_WRITE | PROT_EXEC,
+ MAP_ANONYMOUS | MAP_PRIVATE, 0);
+ if (user_addr >= TASK_SIZE) {
+ pr_warn("Failed to allocate user memory\n");
+ return;
+ }
+
+ if (copy_to_user((void __user *)user_addr, &user_data,
+ sizeof(user_data))) {
+ pr_warn("copy_to_user failed\n");
+ goto free_user;
+ }
+
+ phys_addr = user_virt_to_phys(user_addr);
+ if (!phys_addr) {
+ pr_warn("Failed to get physical address of user memory\n");
+ goto free_user;
+ }
+
+ virt_addr = phys_to_virt(phys_addr);
+ if (phys_addr != virt_to_phys(virt_addr)) {
+ pr_warn("Physical address of user memory seems incorrect\n");
+ goto free_user;
+ }
+
+ pr_info("Attempting bad read from kernel address %p\n", virt_addr);
+ if (*(unsigned long *)virt_addr == user_data)
+ pr_info("Huh? Bad read succeeded?!\n");
+ else
+ pr_info("Huh? Bad read didn't fail but data is incorrect?!\n");
+
+ free_user:
+ vm_munmap(user_addr, PAGE_SIZE);
+}
--
2.11.0
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