Date:	Fri, 04 Dec 2009 17:12:11 +0800
From:	Shane Wang <shane.wang@...el.com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	"Cihula, Joseph" <joseph.cihula@...el.com>,
	"arjan@...ux.intel.com" <arjan@...ux.intel.com>,
	Andi Kleen <andi@...stfloor.org>,
	"chrisw@...s-sol.org" <chrisw@...s-sol.org>,
	"jmorris@...ei.org" <jmorris@...ei.org>,
	"jbeulich@...ell.com" <jbeulich@...ell.com>,
	"peterm@...hat.com" <peterm@...hat.com>, len.brown@...el.com,
	Pavel Machek <pavel@....cz>, "Rafael J. Wysocki" <rjw@...k.pl>,
	linux-pm@...ts.linux-foundation.org, shane.wang@...el.com
Subject: [PATCH] intel_txt: add s3 userspace memory integrity verification

This patch added verification for userspace memory integrity after S3 resume.
Integrity verification for other memory (say kernel itself) has been done by tboot.

Thanks
Shane

---
  arch/x86/kernel/entry_64.S |   20 +++
  arch/x86/kernel/tboot.c    |  226 +++++++++++++++++++++++++++++++++++
  drivers/acpi/sleep.c       |    3
  include/linux/mm.h         |    8 -
  include/linux/tboot.h      |    3
  security/Kconfig           |    2
  6 files changed, 256 insertions(+), 6 deletions(-)

Signed-off-by: Shane Wang <shane.wang@...el.com>
Signed-off-by: Joseph Cihula <joseph.cihula@...el.com>

diff -r c878d454dc8b arch/x86/kernel/entry_64.S
--- a/arch/x86/kernel/entry_64.S	Wed Dec 02 01:06:32 2009 -0800
+++ b/arch/x86/kernel/entry_64.S	Thu Dec 03 07:22:17 2009 -0800
@@ -1275,6 +1275,26 @@ ENTRY(call_softirq)
  	CFI_ENDPROC
  END(call_softirq)

+#ifdef CONFIG_INTEL_TXT
+/* void tboot_switch_stack_call(void (*target_func)(void), u64 new_rsp) */
+ENTRY(tboot_switch_stack_call)
+	CFI_STARTPROC
+	push %rbp
+	CFI_ADJUST_CFA_OFFSET	8
+	CFI_REL_OFFSET	rbp,0
+	mov %rsp, %rbp
+	CFI_DEF_CFA_REGISTER	rbp
+	mov %rsi, %rsp
+	push %rbp
+	call *%rdi
+	leaveq
+	CFI_DEF_CFA_REGISTER	rsp
+	CFI_ADJUST_CFA_OFFSET	-8
+	ret
+	CFI_ENDPROC
+END(tboot_switch_stack_call)
+#endif
+
  #ifdef CONFIG_XEN
  zeroentry xen_hypervisor_callback xen_do_hypervisor_callback

diff -r c878d454dc8b arch/x86/kernel/tboot.c
--- a/arch/x86/kernel/tboot.c	Wed Dec 02 01:06:32 2009 -0800
+++ b/arch/x86/kernel/tboot.c	Thu Dec 03 07:22:17 2009 -0800
@@ -20,6 +20,7 @@
   */

  #include <linux/dma_remapping.h>
+#include <linux/scatterlist.h>
  #include <linux/init_task.h>
  #include <linux/spinlock.h>
  #include <linux/delay.h>
@@ -30,12 +31,17 @@
  #include <linux/pfn.h>
  #include <linux/mm.h>
  #include <linux/tboot.h>
+#include <linux/random.h>
+
+#include <crypto/vmac.h>
+#include <crypto/hash.h>

  #include <asm/trampoline.h>
  #include <asm/processor.h>
  #include <asm/bootparam.h>
  #include <asm/pgtable.h>
  #include <asm/pgalloc.h>
+#include <asm/percpu.h>
  #include <asm/fixmap.h>
  #include <asm/proto.h>
  #include <asm/setup.h>
@@ -168,6 +174,159 @@ static void tboot_create_trampoline(void
  		      map_base, map_size);
  }

+#ifdef CONFIG_X86_64
+static char *new_stack, *new_stack_ptr;
+
+static int tboot_pre_stack_switch(void)
+{
+	BUG_ON((new_stack != NULL) || (new_stack_ptr != NULL));
+
+	/*
+	 * as long as thread info is above 4G, then switch stack,
+	 * since tboot can't access >4G stack for MACing
+	 */
+	if (!((PFN_PHYS(PFN_DOWN(virt_to_phys(current_thread_info())))
+		+ (PFN_UP(THREAD_SIZE) << PAGE_SHIFT))
+		& 0xffffffff00000000UL))
+		return -1;
+
+	new_stack = (char *)__get_free_pages(GFP_DMA32, IRQ_STACK_ORDER);
+
+	BUG_ON(new_stack == NULL);
+	memset(new_stack, 0, IRQ_STACK_SIZE);
+	new_stack_ptr = new_stack + IRQ_STACK_SIZE - 64;
+
+	return 0;
+}
+
+static void tboot_post_stack_switch(void)
+{
+	BUG_ON((new_stack == NULL) || (new_stack_ptr == NULL));
+
+	free_pages((unsigned long)new_stack, IRQ_STACK_ORDER);
+	new_stack = NULL;
+	new_stack_ptr = NULL;
+}
+
+extern void tboot_switch_stack_call(void (*target_func)(void), u64 new_rsp);
+
+#else /* CONFIG_X86_32 */
+
+#define tboot_pre_stack_switch()			(-1)
+#define tboot_post_stack_switch()			do { } while (0)
+#define tboot_switch_stack_call(target_func, new_rsp)	do { } while (0)
+
+#endif
+
+static vmac_t mem_mac;
+static struct crypto_hash *tfm;
+
+static int tboot_gen_mem_integrity(const uint8_t key[], vmac_t *mac)
+{
+	int i, j, ret;
+	pg_data_t *pgdat;
+	struct hash_desc desc;
+	struct scatterlist sg[1];
+	struct page *page;
+	uint64_t paddr, rstart, rend;
+	unsigned long pfn;
+	uint8_t zeroed_key[VMAC_KEY_LEN];
+
+	if (!tfm)
+		tfm = crypto_alloc_hash("vmac(aes)", 0, CRYPTO_ALG_ASYNC);
+
+	if (IS_ERR(tfm)) {
+		tfm = NULL;
+		return -ENOMEM;
+	}
+
+	desc.tfm = tfm;
+	desc.flags = 0;
+
+	sg_init_table(sg, 1);
+
+	ret = crypto_hash_init(&desc);
+	if (ret)
+		return ret;
+	ret = crypto_hash_setkey(desc.tfm, key, VMAC_KEY_LEN);
+	if (ret)
+		return ret;
+
+	for_each_online_pgdat(pgdat) {
+		unsigned long flags;
+
+		pgdat_resize_lock(pgdat, &flags);
+		for (i = 0, pfn = pgdat->node_start_pfn;
+			i < pgdat->node_spanned_pages;
+			i++, pfn = pgdat->node_start_pfn + i) {
+
+			if (!pfn_valid(pfn) || !page_is_ram(pfn))
+				continue;
+
+			page = pfn_to_page(pfn);
+			paddr = page_to_phys(page);
+
+			/* If pg will be MACed by tboot, no need to MAC here */
+			for (j = 0; j < tboot->num_mac_regions; j++) {
+				rstart = tboot->mac_regions[j].start;
+				rend = rstart +	tboot->mac_regions[j].size;
+				if (((paddr + PAGE_SIZE) <= rstart)
+					|| (rend <= paddr))
+					continue;
+				break;
+			}
+
+			if (j == tboot->num_mac_regions) {
+				sg_set_page(sg, page, PAGE_SIZE, 0);
+#ifdef CONFIG_DEBUG_PAGEALLOC
+			/*
+			 * check if the page we are going to MAC is marked as
+			 * present in the kernel page tables.
+			 */
+			if (!kernel_page_present(page)) {
+				kernel_map_pages(page, 1, 1);
+				ret = crypto_hash_update(&desc, sg, PAGE_SIZE);
+				kernel_map_pages(page, 1, 0);
+			} else
+#endif
+				ret = crypto_hash_update(&desc, sg, PAGE_SIZE);
+				if (ret) {
+					pgdat_resize_unlock(pgdat, &flags);
+					return ret;
+				}
+			}
+		}
+		pgdat_resize_unlock(pgdat, &flags);
+	}
+
+#ifdef CONFIG_X86_64
+	/*
+	 * for stack > 4G, we should MAC the stack in the kernel after switch,
+	 * for stack < 4G, the stack is MACed by tboot
+	 */
+	if (new_stack) {
+		for (i = 0, page = virt_to_page((void *)current_thread_info());
+			i < (1 << THREAD_ORDER);
+			i++, page++) {
+			sg_set_page(sg, page, PAGE_SIZE, 0);
+			ret = crypto_hash_update(&desc, sg, PAGE_SIZE);
+			if (ret)
+				return ret;
+		}
+	}
+#endif
+
+	ret = crypto_hash_final(&desc, (uint8_t *)mac);
+	if (ret)
+		return ret;
+
+	/* Clean the key */
+	memset(zeroed_key, 0, sizeof(zeroed_key));
+	crypto_hash_setkey(desc.tfm, zeroed_key, VMAC_KEY_LEN);
+
+	return 0;
+}
+
  #ifdef CONFIG_ACPI_SLEEP

  static void add_mac_region(phys_addr_t start, unsigned long size)
@@ -196,6 +355,27 @@ static int tboot_setup_sleep(void)

  	/* kernel code + data + bss */
  	add_mac_region(virt_to_phys(_text), _end - _text);
+
+	/* stack */
+#ifdef CONFIG_X86_64
+	/*
+	 * if stack > 4G, we should MAC the stack in the kernel after switch,
+	 * if stack < 4G, the stack is MACed by tboot
+	 */
+	if (new_stack)
+		add_mac_region(virt_to_phys(new_stack),
+				IRQ_STACK_SIZE); /* > 4G */
+	else
+#endif
+		add_mac_region(virt_to_phys(current_thread_info()),
+				THREAD_SIZE); /* < 4G */
+
+	/* MAC userspace memory not handled by tboot */
+	get_random_bytes(tboot->s3_key, sizeof(tboot->s3_key));
+	if (tboot_gen_mem_integrity(tboot->s3_key, &mem_mac)) {
+		panic("tboot: vmac generation failed\n");
+		return -1;
+	}

  	tboot->acpi_sinfo.kernel_s3_resume_vector = acpi_wakeup_address;

@@ -292,6 +472,52 @@ void tboot_sleep(u8 sleep_state, u32 pm1
  	}

  	tboot_shutdown(acpi_shutdown_map[sleep_state]);
+}
+
+static void tboot_sx_resume(void)
+{
+	vmac_t mac;
+
+	if (tboot_gen_mem_integrity(tboot->s3_key, &mac))
+		panic("tboot: vmac generation failed\n");
+	else if (mac != mem_mac)
+#ifdef CONFIG_DEBUG_KERNEL
+		pr_debug("tboot: memory integrity %llx -> %llx\n",
+				mem_mac, mac);
+#else
+		panic("tboot: memory integrity was lost on resume\n");
+#endif
+	else
+		pr_info("memory integrity OK\n");
+
+	/* Clean s3_key */
+	memset(tboot->s3_key, 0, sizeof(tboot->s3_key));
+}
+
+extern void do_suspend_lowlevel(void);
+
+static void tboot_do_suspend_lowlevel_call(void)
+{
+	do_suspend_lowlevel();
+	tboot_sx_resume();
+}
+
+void tboot_do_suspend_lowlevel(void)
+{
+	int ret = -1;
+
+	if (!tboot_enabled()) {
+		do_suspend_lowlevel();
+		return;
+	}
+
+	ret = tboot_pre_stack_switch();
+	if (!ret) {
+		tboot_switch_stack_call(tboot_do_suspend_lowlevel_call,
+					(u64)new_stack_ptr);
+		tboot_post_stack_switch();
+	} else
+		tboot_do_suspend_lowlevel_call();
  }

  static atomic_t ap_wfs_count;
diff -r c878d454dc8b drivers/acpi/sleep.c
--- a/drivers/acpi/sleep.c	Wed Dec 02 01:06:32 2009 -0800
+++ b/drivers/acpi/sleep.c	Thu Dec 03 07:22:17 2009 -0800
@@ -16,6 +16,7 @@
  #include <linux/device.h>
  #include <linux/suspend.h>
  #include <linux/reboot.h>
+#include <linux/tboot.h>

  #include <asm/io.h>

@@ -244,7 +245,7 @@ static int acpi_suspend_enter(suspend_st
  		break;

  	case ACPI_STATE_S3:
-		do_suspend_lowlevel();
+		tboot_do_suspend_lowlevel();
  		break;
  	}

diff -r c878d454dc8b include/linux/mm.h
--- a/include/linux/mm.h	Wed Dec 02 01:06:32 2009 -0800
+++ b/include/linux/mm.h	Thu Dec 03 07:22:17 2009 -0800
@@ -1263,18 +1263,18 @@ static inline void enable_debug_pageallo
  {
  	debug_pagealloc_enabled = 1;
  }
-#ifdef CONFIG_HIBERNATION
+#if defined(CONFIG_HIBERNATION) || defined(CONFIG_INTEL_TXT)
  extern bool kernel_page_present(struct page *page);
-#endif /* CONFIG_HIBERNATION */
+#endif /* CONFIG_HIBERNATION || CONFIG_INTEL_TXT */
  #else
  static inline void
  kernel_map_pages(struct page *page, int numpages, int enable) {}
  static inline void enable_debug_pagealloc(void)
  {
  }
-#ifdef CONFIG_HIBERNATION
+#if defined(CONFIG_HIBERNATION) || defined(CONFIG_INTEL_TXT)
  static inline bool kernel_page_present(struct page *page) { return true; }
-#endif /* CONFIG_HIBERNATION */
+#endif /* CONFIG_HIBERNATION || CONFIG_INTEL_TXT */
  #endif

  extern struct vm_area_struct *get_gate_vma(struct task_struct *tsk);
diff -r c878d454dc8b include/linux/tboot.h
--- a/include/linux/tboot.h	Wed Dec 02 01:06:32 2009 -0800
+++ b/include/linux/tboot.h	Thu Dec 03 07:22:17 2009 -0800
@@ -147,7 +147,7 @@ extern struct acpi_table_header *tboot_g
  extern struct acpi_table_header *tboot_get_dmar_table(
  				      struct acpi_table_header *dmar_tbl);
  extern int tboot_force_iommu(void);
-
+extern void tboot_do_suspend_lowlevel(void);
  #else

  #define tboot_probe()			do { } while (0)
@@ -156,6 +156,7 @@ extern int tboot_force_iommu(void);
  					do { } while (0)
  #define tboot_get_dmar_table(dmar_tbl)	(dmar_tbl)
  #define tboot_force_iommu()		0
+#define tboot_do_suspend_lowlevel()	do_suspend_lowlevel()

  #endif /* !CONFIG_INTEL_TXT */

diff -r c878d454dc8b security/Kconfig
--- a/security/Kconfig	Wed Dec 02 01:06:32 2009 -0800
+++ b/security/Kconfig	Thu Dec 03 07:22:17 2009 -0800
@@ -116,6 +116,8 @@ config INTEL_TXT
  config INTEL_TXT
  	bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
  	depends on HAVE_INTEL_TXT
+	select CRYPTO_VMAC
+	select CRYPTO_AES
  	help
  	  This option enables support for booting the kernel with the
  	  Trusted Boot (tboot) module. This will utilize

View attachment "s3.patch" of type "text/plain" (10253 bytes)

Powered by blists - more mailing lists