From: Juerg Haefliger <juerg.haefli...@canonical.com>
This test simply reads from userspace memory via the kernel's linear
map.
v6: * drop an #ifdef, just let the test fail if XPFO is not supported
* add XPFO_SMP test to try and test the case when one CPU does an xpfo
unmap of an address, that it can't be used accidentally by other
CPUs.
Signed-off-by: Juerg Haefliger <juerg.haefli...@canonical.com>
Signed-off-by: Tycho Andersen <ty...@tycho.ws>
Tested-by: Marco Benatto <marco.antonio....@gmail.com>
[jstec...@amazon.de: rebased from v4.13 to v4.19]
Signed-off-by: Julian Stecklina <jstec...@amazon.de>
Tested-by: Khalid Aziz <khalid.a...@oracle.com>
Cc: Khalid Aziz <kha...@gonehiking.org>
---
drivers/misc/lkdtm/Makefile | 1 +
drivers/misc/lkdtm/core.c | 3 +
drivers/misc/lkdtm/lkdtm.h | 5 +
drivers/misc/lkdtm/xpfo.c | 196 ++++++++++++++++++++++++++++++++++++
4 files changed, 205 insertions(+)
create mode 100644 drivers/misc/lkdtm/xpfo.c
diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile
index 951c984de61a..97c6b7818cce 100644
--- a/drivers/misc/lkdtm/Makefile
+++ b/drivers/misc/lkdtm/Makefile
@@ -9,6 +9,7 @@ lkdtm-$(CONFIG_LKDTM) += refcount.o
lkdtm-$(CONFIG_LKDTM) += rodata_objcopy.o
lkdtm-$(CONFIG_LKDTM) += usercopy.o
lkdtm-$(CONFIG_LKDTM) += stackleak.o
+lkdtm-$(CONFIG_LKDTM) += xpfo.o
KASAN_SANITIZE_stackleak.o := n
KCOV_INSTRUMENT_rodata.o := n
diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index 2837dc77478e..25f4ab4ebf50 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -185,6 +185,9 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(USERCOPY_KERNEL),
CRASHTYPE(USERCOPY_KERNEL_DS),
CRASHTYPE(STACKLEAK_ERASING),
+ CRASHTYPE(XPFO_READ_USER),
+ CRASHTYPE(XPFO_READ_USER_HUGE),
+ CRASHTYPE(XPFO_SMP),
};
diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h
index 3c6fd327e166..6b31ff0c7f8f 100644
--- a/drivers/misc/lkdtm/lkdtm.h
+++ b/drivers/misc/lkdtm/lkdtm.h
@@ -87,4 +87,9 @@ void lkdtm_USERCOPY_KERNEL_DS(void);
/* lkdtm_stackleak.c */
void lkdtm_STACKLEAK_ERASING(void);
+/* lkdtm_xpfo.c */
+void lkdtm_XPFO_READ_USER(void);
+void lkdtm_XPFO_READ_USER_HUGE(void);
+void lkdtm_XPFO_SMP(void);
+
#endif
diff --git a/drivers/misc/lkdtm/xpfo.c b/drivers/misc/lkdtm/xpfo.c
new file mode 100644
index 000000000000..8876128f0144
--- /dev/null
+++ b/drivers/misc/lkdtm/xpfo.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This is for all the tests related to XPFO (eXclusive Page Frame Ownership).
+ */
+
+#include "lkdtm.h"
+
+#include <linux/cpumask.h>
+#include <linux/mman.h>
+#include <linux/uaccess.h>
+#include <linux/xpfo.h>
+#include <linux/kthread.h>
+
+#include <linux/delay.h>
+#include <linux/sched/task.h>
+
+#define XPFO_DATA 0xdeadbeef
+
+static unsigned long do_map(unsigned long flags)
+{
+ unsigned long user_addr, user_data = XPFO_DATA;
+
+ user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
+ PROT_READ | PROT_WRITE | PROT_EXEC,
+ flags, 0);
+ if (user_addr >= TASK_SIZE) {
+ pr_warn("Failed to allocate user memory\n");
+ return 0;
+ }
+
+ if (copy_to_user((void __user *)user_addr, &user_data,
+ sizeof(user_data))) {
+ pr_warn("copy_to_user failed\n");
+ goto free_user;
+ }
+
+ return user_addr;
+
+free_user:
+ vm_munmap(user_addr, PAGE_SIZE);
+ return 0;
+}
+
+static unsigned long *user_to_kernel(unsigned long user_addr)
+{
+ phys_addr_t phys_addr;
+ void *virt_addr;
+
+ phys_addr = user_virt_to_phys(user_addr);
+ if (!phys_addr) {
+ pr_warn("Failed to get physical address of user memory\n");
+ return NULL;
+ }
+
+ 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");
+ return NULL;
+ }
+
+ return virt_addr;
+}
+
+static void read_map(unsigned long *virt_addr)
+{
+ pr_info("Attempting bad read from kernel address %p\n", virt_addr);
+ if (*(unsigned long *)virt_addr == XPFO_DATA)
+ pr_err("FAIL: Bad read succeeded?!\n");
+ else
+ pr_err("FAIL: Bad read didn't fail but data is incorrect?!\n");
+}
+
+static void read_user_with_flags(unsigned long flags)
+{
+ unsigned long user_addr, *kernel;
+
+ user_addr = do_map(flags);
+ if (!user_addr) {
+ pr_err("FAIL: map failed\n");
+ return;
+ }
+
+ kernel = user_to_kernel(user_addr);
+ if (!kernel) {
+ pr_err("FAIL: user to kernel conversion failed\n");
+ goto free_user;
+ }
+
+ read_map(kernel);
+
+free_user:
+ vm_munmap(user_addr, PAGE_SIZE);
+}
+
+/* Read from userspace via the kernel's linear map. */
+void lkdtm_XPFO_READ_USER(void)
+{
+ read_user_with_flags(MAP_PRIVATE | MAP_ANONYMOUS);
+}
+
+void lkdtm_XPFO_READ_USER_HUGE(void)
+{
+ read_user_with_flags(MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB);
+}
+
+struct smp_arg {
+ unsigned long *virt_addr;
+ unsigned int cpu;
+};
+
+static int smp_reader(void *parg)
+{
+ struct smp_arg *arg = parg;
+ unsigned long *virt_addr;
+
+ if (arg->cpu != smp_processor_id()) {
+ pr_err("FAIL: scheduled on wrong CPU?\n");
+ return 0;
+ }
+
+ virt_addr = smp_cond_load_acquire(&arg->virt_addr, VAL != NULL);
+ read_map(virt_addr);
+
+ return 0;
+}
+
+#ifdef CONFIG_X86
+#define XPFO_SMP_KILLED SIGKILL
+#elif CONFIG_ARM64
+#define XPFO_SMP_KILLED SIGSEGV
+#else
+#error unsupported arch
+#endif
+
+/* The idea here is to read from the kernel's map on a different thread than
+ * did the mapping (and thus the TLB flushing), to make sure that the page
+ * faults on other cores too.
+ */
+void lkdtm_XPFO_SMP(void)
+{
+ unsigned long user_addr, *virt_addr;
+ struct task_struct *thread;
+ int ret;
+ struct smp_arg arg;
+
+ if (num_online_cpus() < 2) {
+ pr_err("not enough to do a multi cpu test\n");
+ return;
+ }
+
+ arg.virt_addr = NULL;
+ arg.cpu = (smp_processor_id() + 1) % num_online_cpus();
+ thread = kthread_create(smp_reader, &arg, "lkdtm_xpfo_test");
+ if (IS_ERR(thread)) {
+ pr_err("couldn't create kthread? %ld\n", PTR_ERR(thread));
+ return;
+ }
+
+ kthread_bind(thread, arg.cpu);
+ get_task_struct(thread);
+ wake_up_process(thread);
+
+ user_addr = do_map(MAP_PRIVATE | MAP_ANONYMOUS);
+ if (!user_addr)
+ goto kill_thread;
+
+ virt_addr = user_to_kernel(user_addr);
+ if (!virt_addr) {
+ /*
+ * let's store something that will fail, so we can unblock the
+ * thread
+ */
+ smp_store_release(&arg.virt_addr, &arg);
+ goto free_user;
+ }
+
+ /* Store to test address to unblock the thread */
+ smp_store_release(&arg.virt_addr, virt_addr);
+
+ /* there must be a better way to do this. */
+ while (1) {
+ if (thread->exit_state)
+ break;
+ msleep_interruptible(100);
+ }
+
+free_user:
+ if (user_addr)
+ vm_munmap(user_addr, PAGE_SIZE);
+
+kill_thread:
+ ret = kthread_stop(thread);
+ if (ret != XPFO_SMP_KILLED)
+ pr_err("FAIL: thread wasn't killed: %d\n", ret);
+ put_task_struct(thread);
+}
--
2.17.1
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