Re: [PATCH 2/2] No-exec support for ppc64

Jake Moilanen
2005-03-11T14:09:58Z

On Fri, 11 Mar 2005 09:44:28 +1100
Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:

>
>
> > /* Free memory returned from module_alloc */
> > diff -puN arch/ppc64/mm/fault.c~nx-kernel-ppc64 arch/ppc64/mm/fault.c
> > --- linux-2.6-bk/arch/ppc64/mm/fault.c~nx-kernel-ppc64 2005-03-10 13:54:14 -06:00
> > +++ linux-2.6-bk-moilanen/arch/ppc64/mm/fault.c 2005-03-10 13:54:14 -06:00
> > @@ -76,6 +76,13 @@ static int store_updates_sp(struct pt_re
> > return 0;
> > }
> >
> > +pte_t *lookup_address(unsigned long address)
> > +{
> > + pgd_t *pgd = pgd_offset_k(address);
> > +
> > + return find_linux_pte(pgd, address);
> > +}
>
> static please, even inline in this case.
>
> I've removed Andrew from CC upon his request, Paul, Anton or I will
> forward to him when it's ready, no need to clobber his mailbox in the
> meantime.

3rd time is a charm.

Signed-off-by: Jake Moilanen <moilanen@austin.ibm.com>

---

linux-2.6-bk-moilanen/arch/ppc64/kernel/iSeries_setup.c | 4 +++
linux-2.6-bk-moilanen/arch/ppc64/kernel/module.c | 3 +-
linux-2.6-bk-moilanen/arch/ppc64/mm/fault.c | 19 ++++++++++++++++
linux-2.6-bk-moilanen/arch/ppc64/mm/hash_utils.c | 19 ++++++++++------
linux-2.6-bk-moilanen/include/asm-ppc64/pgtable.h | 1
linux-2.6-bk-moilanen/include/asm-ppc64/sections.h | 9 +++++++
6 files changed, 48 insertions(+), 7 deletions(-)

diff -puN arch/ppc64/kernel/iSeries_setup.c~nx-kernel-ppc64 arch/ppc64/kernel/iSeries_setup.c
--- linux-2.6-bk/arch/ppc64/kernel/iSeries_setup.c~nx-kernel-ppc64 2005-03-11 07:50:39 -06:00
+++ linux-2.6-bk-moilanen/arch/ppc64/kernel/iSeries_setup.c 2005-03-11 07:50:39 -06:00
@@ -633,6 +633,10 @@ static void __init iSeries_bolt_kernel(u
unsigned long vpn = va >> PAGE_SHIFT;
unsigned long slot = HvCallHpt_findValid(&hpte, vpn);

+ /* Make non-kernel text non-executable */
+ if (!in_kernel_text(ea))
+ mode_rw |= HW_NO_EXEC;
+
if (hpte.dw0.dw0.v) {
/* HPTE exists, so just bolt it */
HvCallHpt_setSwBits(slot, 0x10, 0);
diff -puN arch/ppc64/kernel/module.c~nx-kernel-ppc64 arch/ppc64/kernel/module.c
--- linux-2.6-bk/arch/ppc64/kernel/module.c~nx-kernel-ppc64 2005-03-11 07:50:39 -06:00
+++ linux-2.6-bk-moilanen/arch/ppc64/kernel/module.c 2005-03-11 07:50:39 -06:00
@@ -102,7 +102,8 @@ void *module_alloc(unsigned long size)
{
if (size == 0)
return NULL;
- return vmalloc(size);
+
+ return vmalloc_exec(size);
}

/* Free memory returned from module_alloc */
diff -puN arch/ppc64/mm/fault.c~nx-kernel-ppc64 arch/ppc64/mm/fault.c
--- linux-2.6-bk/arch/ppc64/mm/fault.c~nx-kernel-ppc64 2005-03-11 07:50:39 -06:00
+++ linux-2.6-bk-moilanen/arch/ppc64/mm/fault.c 2005-03-11 07:50:57 -06:00
@@ -76,6 +76,13 @@ static int store_updates_sp(struct pt_re
return 0;
}

+static inline pte_t *lookup_address(unsigned long address)
+{
+ pgd_t *pgd = pgd_offset_k(address);
+
+ return find_linux_pte(pgd, address);
+}
+
/*
* The error_code parameter is
* - DSISR for a non-SLB data access fault,
@@ -94,6 +101,7 @@ int do_page_fault(struct pt_regs *regs,
unsigned long is_write = error_code & 0x02000000;
unsigned long trap = TRAP(regs);
unsigned long is_exec = trap == 0x400;
+ pte_t *ptep;

BUG_ON((trap == 0x380) || (trap == 0x480));

@@ -253,6 +261,17 @@ bad_area_nosemaphore:
info.si_addr = (void __user *) address;
force_sig_info(SIGSEGV, &info, current);
return 0;
+ }
+
+ ptep = lookup_address(address);
+
+ if (ptep && pte_present(*ptep) && !pte_exec(*ptep)) {
+ if (printk_ratelimit())
+ printk(KERN_CRIT "kernel tried to execute NX-protected "
+ "page - exploit attempt? (uid: %d)\n",
+ current->uid);
+ show_stack(current, (unsigned long *)__get_SP());
+ do_exit(SIGKILL);
}

return SIGSEGV;
diff -puN arch/ppc64/mm/hash_utils.c~nx-kernel-ppc64 arch/ppc64/mm/hash_utils.c
--- linux-2.6-bk/arch/ppc64/mm/hash_utils.c~nx-kernel-ppc64 2005-03-11 07:50:39 -06:00
+++ linux-2.6-bk-moilanen/arch/ppc64/mm/hash_utils.c 2005-03-11 07:59:53 -06:00
@@ -51,6 +51,7 @@
#include <asm/cacheflush.h>
#include <asm/cputable.h>
#include <asm/abs_addr.h>
+#include <asm/sections.h>

#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
@@ -95,6 +96,7 @@ static inline void create_pte_mapping(un
{
unsigned long addr;
unsigned int step;
+ unsigned long tmp_mode;

if (large)
step = 16*MB;
@@ -112,6 +114,13 @@ static inline void create_pte_mapping(un
else
vpn = va >> PAGE_SHIFT;

+
+ tmp_mode = mode;
+
+ /* Make non-kernel text non-executable */
+ if (!in_kernel_text(addr))
+ tmp_mode = mode | HW_NO_EXEC;
+
hash = hpt_hash(vpn, large);

hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);
@@ -120,12 +129,12 @@ static inline void create_pte_mapping(un
if (systemcfg->platform & PLATFORM_LPAR)
ret = pSeries_lpar_hpte_insert(hpteg, va,
virt_to_abs(addr) >> PAGE_SHIFT,
- 0, mode, 1, large);
+ 0, tmp_mode, 1, large);
else
#endif /* CONFIG_PPC_PSERIES */
ret = native_hpte_insert(hpteg, va,
virt_to_abs(addr) >> PAGE_SHIFT,
- 0, mode, 1, large);
+ 0, tmp_mode, 1, large);

if (ret == -1) {
ppc64_terminate_msg(0x20, "create_pte_mapping");
@@ -238,8 +247,6 @@ unsigned int hash_page_do_lazy_icache(un
{
struct page *page;

-#define PPC64_HWNOEXEC (1 << 2)
-
if (!pfn_valid(pte_pfn(pte)))
return pp;

@@ -250,8 +257,8 @@ unsigned int hash_page_do_lazy_icache(un
if (trap == 0x400) {
__flush_dcache_icache(page_address(page));
set_bit(PG_arch_1, &page->flags);
- } else
- pp |= PPC64_HWNOEXEC;
+ } else
+ pp |= HW_NO_EXEC;
}
return pp;
}
diff -puN include/asm-ppc64/pgtable.h~nx-kernel-ppc64 include/asm-ppc64/pgtable.h
--- linux-2.6-bk/include/asm-ppc64/pgtable.h~nx-kernel-ppc64 2005-03-11 07:50:39 -06:00
+++ linux-2.6-bk-moilanen/include/asm-ppc64/pgtable.h 2005-03-11 07:50:39 -06:00
@@ -117,6 +117,7 @@
#define PAGE_READONLY __pgprot(_PAGE_BASE | _PAGE_USER)
#define PAGE_READONLY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
#define PAGE_KERNEL __pgprot(_PAGE_BASE | _PAGE_WRENABLE)
+#define PAGE_KERNEL_EXEC __pgprot(_PAGE_BASE | _PAGE_WRENABLE | _PAGE_EXEC)

#define HW_NO_EXEC _PAGE_EXEC /* This is used when the bit is
* inverted, even though it's the
diff -puN include/asm-ppc64/sections.h~nx-kernel-ppc64 include/asm-ppc64/sections.h
--- linux-2.6-bk/include/asm-ppc64/sections.h~nx-kernel-ppc64 2005-03-11 07:50:39 -06:00
+++ linux-2.6-bk-moilanen/include/asm-ppc64/sections.h 2005-03-11 07:50:39 -06:00
@@ -17,4 +17,13 @@ extern char _end[];
#define __openfirmware
#define __openfirmwaredata

+
+static inline int in_kernel_text(unsigned long addr)
+{
+ if (addr >= (unsigned long)_stext && addr < (unsigned long)__init_end)
+ return 1;
+
+ return 0;
+}
+
#endif

_