From mboxrd@z Thu Jan 1 00:00:00 1970 From: Khalid Aziz Subject: [RFC PATCH v8 10/14] lkdtm: Add test for XPFO Date: Wed, 13 Feb 2019 17:01:33 -0700 Message-Id: <1af3c61568d36cad4a2b2fece978336620701b86.1550088114.git.khalid.aziz@oracle.com> In-Reply-To: References: In-Reply-To: References: To: juergh@gmail.com, tycho@tycho.ws, jsteckli@amazon.de, ak@linux.intel.com, torvalds@linux-foundation.org, liran.alon@oracle.com, keescook@google.com, akpm@linux-foundation.org, mhocko@suse.com, catalin.marinas@arm.com, will.deacon@arm.com, jmorris@namei.org, konrad.wilk@oracle.com Cc: Juerg Haefliger , deepa.srinivasan@oracle.com, chris.hyser@oracle.com, tyhicks@canonical.com, dwmw@amazon.co.uk, andrew.cooper3@citrix.com, jcm@redhat.com, boris.ostrovsky@oracle.com, kanth.ghatraju@oracle.com, oao.m.martins@oracle.com, jmattson@google.com, pradeep.vincent@oracle.com, john.haxby@oracle.com, tglx@linutronix.de, kirill.shutemov@linux.intel.com, hch@lst.de, steven.sistare@oracle.com, labbott@redhat.com, luto@kernel.org, dave.hansen@intel.com, peterz@infradead.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Tycho Andersen List-ID: From: Juerg Haefliger 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 Signed-off-by: Tycho Andersen Tested-by: Marco Benatto [jsteckli@amazon.de: rebased from v4.13 to v4.19] Signed-off-by: Julian Stecklina Tested-by: Khalid Aziz --- drivers/misc/lkdtm/Makefile | 1 + drivers/misc/lkdtm/core.c | 3 + drivers/misc/lkdtm/lkdtm.h | 5 + drivers/misc/lkdtm/xpfo.c | 194 ++++++++++++++++++++++++++++++++++++ 4 files changed, 203 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..d903063bdd0b --- /dev/null +++ b/drivers/misc/lkdtm/xpfo.c @@ -0,0 +1,194 @@ +/* + * This is for all the tests related to XPFO (eXclusive Page Frame Ownership). + */ + +#include "lkdtm.h" + +#include +#include +#include +#include +#include + +#include +#include + +#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; + } + + 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