Merge branch 'x86-security-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-security-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  module: Move RO/NX module protection to after ftrace module update
  x86: Resume trampoline must be executable
  x86: Add RO/NX protection for loadable kernel modules
  x86: Add NX protection for kernel data
  x86: Fix improper large page preservation

3 files changed, 43 insertions, 13 deletions

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index c0e28a1..947f42ab 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -364,8 +364,9 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
 	/*
 	 * We just marked the kernel text read only above, now that
 	 * we are going to free part of that, we need to make that
-	 * writeable first.
+	 * writeable and non-executable first.
 	 */
+	set_memory_nx(begin, (end - begin) >> PAGE_SHIFT);
 	set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);
 
 	printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10);
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 0e969f9..f89b5bb 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -226,7 +226,7 @@ page_table_range_init(unsigned long start, unsigned long end, pgd_t *pgd_base)
 
 static inline int is_kernel_text(unsigned long addr)
 {
-	if (addr >= PAGE_OFFSET && addr <= (unsigned long)__init_end)
+	if (addr >= (unsigned long)_text && addr <= (unsigned long)__init_end)
 		return 1;
 	return 0;
 }
@@ -912,6 +912,23 @@ void set_kernel_text_ro(void)
 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
 }
 
+static void mark_nxdata_nx(void)
+{
+	/*
+	 * When this called, init has already been executed and released,
+	 * so everything past _etext sould be NX.
+	 */
+	unsigned long start = PFN_ALIGN(_etext);
+	/*
+	 * This comes from is_kernel_text upper limit. Also HPAGE where used:
+	 */
+	unsigned long size = (((unsigned long)__init_end + HPAGE_SIZE) & HPAGE_MASK) - start;
+
+	if (__supported_pte_mask & _PAGE_NX)
+		printk(KERN_INFO "NX-protecting the kernel data: %luk\n", size >> 10);
+	set_pages_nx(virt_to_page(start), size >> PAGE_SHIFT);
+}
+
 void mark_rodata_ro(void)
 {
 	unsigned long start = PFN_ALIGN(_text);
@@ -946,6 +963,7 @@ void mark_rodata_ro(void)
 	printk(KERN_INFO "Testing CPA: write protecting again\n");
 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
 #endif
+	mark_nxdata_nx();
 }
 #endif
 
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 532e793..8b830ca 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -13,6 +13,7 @@
 #include <linux/pfn.h>
 #include <linux/percpu.h>
 #include <linux/gfp.h>
+#include <linux/pci.h>
 
 #include <asm/e820.h>
 #include <asm/processor.h>
@@ -255,13 +256,16 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
 				   unsigned long pfn)
 {
 	pgprot_t forbidden = __pgprot(0);
+	pgprot_t required = __pgprot(0);
 
 	/*
 	 * The BIOS area between 640k and 1Mb needs to be executable for
 	 * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
 	 */
-	if (within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT))
+#ifdef CONFIG_PCI_BIOS
+	if (pcibios_enabled && within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT))
 		pgprot_val(forbidden) |= _PAGE_NX;
+#endif
 
 	/*
 	 * The kernel text needs to be executable for obvious reasons
@@ -278,6 +282,12 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
 	if (within(pfn, __pa((unsigned long)__start_rodata) >> PAGE_SHIFT,
 		   __pa((unsigned long)__end_rodata) >> PAGE_SHIFT))
 		pgprot_val(forbidden) |= _PAGE_RW;
+	/*
+	 * .data and .bss should always be writable.
+	 */
+	if (within(address, (unsigned long)_sdata, (unsigned long)_edata) ||
+	    within(address, (unsigned long)__bss_start, (unsigned long)__bss_stop))
+		pgprot_val(required) |= _PAGE_RW;
 
 #if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
 	/*
@@ -317,6 +327,7 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
 #endif
 
 	prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));
+	prot = __pgprot(pgprot_val(prot) | pgprot_val(required));
 
 	return prot;
 }
@@ -393,7 +404,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
 {
 	unsigned long nextpage_addr, numpages, pmask, psize, flags, addr, pfn;
 	pte_t new_pte, old_pte, *tmp;
-	pgprot_t old_prot, new_prot;
+	pgprot_t old_prot, new_prot, req_prot;
 	int i, do_split = 1;
 	unsigned int level;
 
@@ -438,10 +449,10 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
 	 * We are safe now. Check whether the new pgprot is the same:
 	 */
 	old_pte = *kpte;
-	old_prot = new_prot = pte_pgprot(old_pte);
+	old_prot = new_prot = req_prot = pte_pgprot(old_pte);
 
-	pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
-	pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);
+	pgprot_val(req_prot) &= ~pgprot_val(cpa->mask_clr);
+	pgprot_val(req_prot) |= pgprot_val(cpa->mask_set);
 
 	/*
 	 * old_pte points to the large page base address. So we need
@@ -450,17 +461,17 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
 	pfn = pte_pfn(old_pte) + ((address & (psize - 1)) >> PAGE_SHIFT);
 	cpa->pfn = pfn;
 
-	new_prot = static_protections(new_prot, address, pfn);
+	new_prot = static_protections(req_prot, address, pfn);
 
 	/*
 	 * We need to check the full range, whether
 	 * static_protection() requires a different pgprot for one of
 	 * the pages in the range we try to preserve:
 	 */
-	addr = address + PAGE_SIZE;
-	pfn++;
-	for (i = 1; i < cpa->numpages; i++, addr += PAGE_SIZE, pfn++) {
-		pgprot_t chk_prot = static_protections(new_prot, addr, pfn);
+	addr = address & pmask;
+	pfn = pte_pfn(old_pte);
+	for (i = 0; i < (psize >> PAGE_SHIFT); i++, addr += PAGE_SIZE, pfn++) {
+		pgprot_t chk_prot = static_protections(req_prot, addr, pfn);
 
 		if (pgprot_val(chk_prot) != pgprot_val(new_prot))
 			goto out_unlock;
@@ -483,7 +494,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
 	 * that we limited the number of possible pages already to
 	 * the number of pages in the large page.
 	 */
-	if (address == (nextpage_addr - psize) && cpa->numpages == numpages) {
+	if (address == (address & pmask) && cpa->numpages == (psize >> PAGE_SHIFT)) {
 		/*
 		 * The address is aligned and the number of pages
 		 * covers the full page.