Re: Patch 4/6 randomize the stack pointer

From: Arjan van de Ven
Date: Thu Jan 27 2005 - 15:29:47 EST


On Thu, Jan 27, 2005 at 08:23:35PM +0000, Christoph Hellwig wrote:
> > + p = arch_align_stack((unsigned long)p);
>
> looking at the code p already is unsigned long, so the cast is not needed.

yeah

how about this one instead ?


The patch below replaces the existing 8Kb randomisation of the userspace
stack pointer (which is currently only done for Hyperthreaded P-IVs) with a
more general randomisation over a 64Kb range. 64Kb is not a lot, but it's a
start and once the dust settles we can increase this value to a more
agressive value.


Signed-off-by Arjan van de Ven <arjanv@xxxxxxxxxx>

diff -purN step1/arch/i386/kernel/process.c step2/arch/i386/kernel/process.c
--- step1/arch/i386/kernel/process.c 2005-01-26 18:24:35.000000000 +0100
+++ step2/arch/i386/kernel/process.c 2005-01-27 21:10:19.000000000 +0100
@@ -36,6 +36,7 @@
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/ptrace.h>
+#include <linux/random.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
@@ -828,3 +829,9 @@ asmlinkage int sys_get_thread_area(struc
return 0;
}

+unsigned long arch_align_stack(unsigned long sp)
+{
+ if (randomize_va_space)
+ sp -= ((get_random_int() % 4096) << 4);
+ return sp & ~0xf;
+}
diff -purN step1/arch/x86_64/kernel/process.c step2/arch/x86_64/kernel/process.c
--- step1/arch/x86_64/kernel/process.c 2005-01-26 18:24:49.000000000 +0100
+++ step2/arch/x86_64/kernel/process.c 2005-01-27 21:10:19.000000000 +0100
@@ -743,3 +743,10 @@ int dump_task_regs(struct task_struct *t

return 1;
}
+
+unsigned long arch_align_stack(unsigned long sp)
+{
+ if (randomize_vs_space)
+ sp -= ((get_random_int() % 4096) << 4);
+ return sp & ~0xf;
+}
diff -purN step1/fs/binfmt_elf.c step2/fs/binfmt_elf.c
--- step1/fs/binfmt_elf.c 2005-01-27 21:09:32.000000000 +0100
+++ step2/fs/binfmt_elf.c 2005-01-27 21:18:58.000000000 +0100
@@ -165,21 +165,14 @@ create_elf_tables(struct linux_binprm *b
if (k_platform) {
size_t len = strlen(k_platform) + 1;

-#ifdef CONFIG_X86_HT
/*
* In some cases (e.g. Hyper-Threading), we want to avoid L1
* evictions by the processes running on the same package. One
* thing we can do is to shuffle the initial stack for them.
- *
- * The conditionals here are unneeded, but kept in to make the
- * code behaviour the same as pre change unless we have
- * hyperthreaded processors. This should be cleaned up
- * before 2.6
*/

- if (smp_num_siblings > 1)
- STACK_ALLOC(p, ((current->pid % 64) << 7));
-#endif
+ p = arch_align_stack(p);
+
u_platform = (elf_addr_t __user *)STACK_ALLOC(p, len);
if (__copy_to_user(u_platform, k_platform, len))
return -EFAULT;
diff -purN step1/fs/exec.c step2/fs/exec.c
--- step1/fs/exec.c 2005-01-27 21:09:32.000000000 +0100
+++ step2/fs/exec.c 2005-01-27 21:18:37.000000000 +0100
@@ -400,7 +400,8 @@ int setup_arg_pages(struct linux_binprm
while (i < MAX_ARG_PAGES)
bprm->page[i++] = NULL;
#else
- stack_base = stack_top - MAX_ARG_PAGES * PAGE_SIZE;
+ stack_base = arch_align_stack(STACK_TOP - MAX_ARG_PAGES*PAGE_SIZE);
+ stack_base = PAGE_ALIGN(stack_base);
bprm->p += stack_base;
mm->arg_start = bprm->p;
arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
diff -purN step1/include/asm-alpha/system.h step2/include/asm-alpha/system.h
--- step1/include/asm-alpha/system.h 2004-12-24 22:34:58.000000000 +0100
+++ step2/include/asm-alpha/system.h 2005-01-27 21:16:20.000000000 +0100
@@ -621,4 +621,6 @@ __cmpxchg(volatile void *ptr, unsigned l

#endif /* __ASSEMBLY__ */

+#define arch_align_stack(x) (x)
+
#endif
diff -purN step1/include/asm-arm/system.h step2/include/asm-arm/system.h
--- step1/include/asm-arm/system.h 2004-12-24 22:34:00.000000000 +0100
+++ step2/include/asm-arm/system.h 2005-01-27 21:16:37.000000000 +0100
@@ -383,6 +383,8 @@ static inline unsigned long __xchg(unsig

#endif /* __ASSEMBLY__ */

+#define arch_align_stack(x) (x)
+
#endif /* __KERNEL__ */

#endif
diff -purN step1/include/asm-arm26/system.h step2/include/asm-arm26/system.h
--- step1/include/asm-arm26/system.h 2005-01-26 18:24:39.000000000 +0100
+++ step2/include/asm-arm26/system.h 2005-01-27 21:16:33.000000000 +0100
@@ -245,6 +245,8 @@ static inline unsigned long __xchg(unsig

#endif /* __ASSEMBLY__ */

+#define arch_align_stack(x) (x)
+
#endif /* __KERNEL__ */

#endif
diff -purN step1/include/asm-cris/system.h step2/include/asm-cris/system.h
--- step1/include/asm-cris/system.h 2004-12-24 22:34:58.000000000 +0100
+++ step2/include/asm-cris/system.h 2005-01-27 21:16:41.000000000 +0100
@@ -69,4 +69,6 @@ extern inline unsigned long __xchg(unsig
return x;
}

+#define arch_align_stack(x) (x)
+
#endif
diff -purN step1/include/asm-frv/system.h step2/include/asm-frv/system.h
--- step1/include/asm-frv/system.h 2005-01-26 18:24:39.000000000 +0100
+++ step2/include/asm-frv/system.h 2005-01-27 21:16:46.000000000 +0100
@@ -120,4 +120,6 @@ do { \
extern void die_if_kernel(const char *, ...) __attribute__((format(printf, 1, 2)));
extern void free_initmem(void);

+#define arch_align_stack(x) (x)
+
#endif /* _ASM_SYSTEM_H */
diff -purN step1/include/asm-h8300/system.h step2/include/asm-h8300/system.h
--- step1/include/asm-h8300/system.h 2004-12-24 22:34:33.000000000 +0100
+++ step2/include/asm-h8300/system.h 2005-01-27 21:16:49.000000000 +0100
@@ -144,4 +144,6 @@ static inline unsigned long __xchg(unsig
asm("jmp @@0"); \
})

+#define arch_align_stack(x) (x)
+
#endif /* _H8300_SYSTEM_H */
diff -purN step1/include/asm-i386/system.h step2/include/asm-i386/system.h
--- step1/include/asm-i386/system.h 2005-01-26 18:24:39.000000000 +0100
+++ step2/include/asm-i386/system.h 2005-01-27 21:13:41.000000000 +0100
@@ -468,4 +468,6 @@ void enable_hlt(void);
extern int es7000_plat;
void cpu_idle_wait(void);

+extern unsigned long arch_align_stack(unsigned long sp);
+
#endif
diff -purN step1/include/asm-ia64/system.h step2/include/asm-ia64/system.h
--- step1/include/asm-ia64/system.h 2005-01-26 18:24:39.000000000 +0100
+++ step2/include/asm-ia64/system.h 2005-01-27 21:17:08.000000000 +0100
@@ -285,6 +285,9 @@ do { \
#define ia64_platform_is(x) (strcmp(x, platform_name) == 0)

void cpu_idle_wait(void);
+
+#define arch_align_stack(x) (x)
+
#endif /* __KERNEL__ */

#endif /* __ASSEMBLY__ */
diff -purN step1/include/asm-m32r/system.h step2/include/asm-m32r/system.h
--- step1/include/asm-m32r/system.h 2005-01-26 18:24:39.000000000 +0100
+++ step2/include/asm-m32r/system.h 2005-01-27 21:17:13.000000000 +0100
@@ -294,4 +294,6 @@ static __inline__ unsigned long __xchg(u
#define set_mb(var, value) do { xchg(&var, value); } while (0)
#define set_wmb(var, value) do { var = value; wmb(); } while (0)

+#define arch_align_stack(x) (x)
+
#endif /* _ASM_M32R_SYSTEM_H */
diff -purN step1/include/asm-m68k/system.h step2/include/asm-m68k/system.h
--- step1/include/asm-m68k/system.h 2004-12-24 22:35:23.000000000 +0100
+++ step2/include/asm-m68k/system.h 2005-01-27 21:17:25.000000000 +0100
@@ -194,6 +194,8 @@ static inline unsigned long __cmpxchg(vo
(unsigned long)(n),sizeof(*(ptr))))
#endif

+#define arch_align_stack(x) (x)
+
#endif /* __KERNEL__ */

#endif /* _M68K_SYSTEM_H */
diff -purN step1/include/asm-m68knommu/system.h step2/include/asm-m68knommu/system.h
--- step1/include/asm-m68knommu/system.h 2004-12-24 22:35:00.000000000 +0100
+++ step2/include/asm-m68knommu/system.h 2005-01-27 21:17:21.000000000 +0100
@@ -281,5 +281,6 @@ cmpxchg(volatile int *p, int old, int ne
})
#endif
#endif
+#define arch_align_stack(x) (x)

#endif /* _M68KNOMMU_SYSTEM_H */
diff -purN step1/include/asm-mips/system.h step2/include/asm-mips/system.h
--- step1/include/asm-mips/system.h 2004-12-24 22:34:32.000000000 +0100
+++ step2/include/asm-mips/system.h 2005-01-27 21:17:29.000000000 +0100
@@ -433,4 +433,6 @@ do { \
#define finish_arch_switch(rq, prev) spin_unlock_irq(&(prev)->switch_lock)
#define task_running(rq, p) ((rq)->curr == (p) || spin_is_locked(&(p)->switch_lock))

+#define arch_align_stack(x) (x)
+
#endif /* _ASM_SYSTEM_H */
diff -purN step1/include/asm-parisc/system.h step2/include/asm-parisc/system.h
--- step1/include/asm-parisc/system.h 2005-01-26 18:24:39.000000000 +0100
+++ step2/include/asm-parisc/system.h 2005-01-27 21:17:36.000000000 +0100
@@ -205,4 +205,6 @@ extern spinlock_t pa_tlb_lock;

#endif

+#define arch_align_stack(x) (x)
+
#endif
diff -purN step1/include/asm-ppc/system.h step2/include/asm-ppc/system.h
--- step1/include/asm-ppc/system.h 2005-01-26 18:24:39.000000000 +0100
+++ step2/include/asm-ppc/system.h 2005-01-27 21:17:43.000000000 +0100
@@ -201,5 +201,7 @@ __cmpxchg(volatile void *ptr, unsigned l
(unsigned long)_n_, sizeof(*(ptr))); \
})

+#define arch_align_stack(x) (x)
+
#endif /* __KERNEL__ */
#endif /* __PPC_SYSTEM_H */
diff -purN step1/include/asm-ppc64/system.h step2/include/asm-ppc64/system.h
--- step1/include/asm-ppc64/system.h 2005-01-26 18:24:39.000000000 +0100
+++ step2/include/asm-ppc64/system.h 2005-01-27 21:17:39.000000000 +0100
@@ -300,5 +300,7 @@ __cmpxchg(volatile void *ptr, unsigned l
*/
#define NET_IP_ALIGN 0

+#define arch_align_stack(x) (x)
+
#endif /* __KERNEL__ */
#endif
diff -purN step1/include/asm-s390/system.h step2/include/asm-s390/system.h
--- step1/include/asm-s390/system.h 2005-01-26 18:24:39.000000000 +0100
+++ step2/include/asm-s390/system.h 2005-01-27 21:17:46.000000000 +0100
@@ -461,6 +461,8 @@ extern void (*_machine_restart)(char *co
extern void (*_machine_halt)(void);
extern void (*_machine_power_off)(void);

+#define arch_align_stack(x) (x)
+
#endif /* __KERNEL__ */

#endif
diff -purN step1/include/asm-sh/system.h step2/include/asm-sh/system.h
--- step1/include/asm-sh/system.h 2004-12-24 22:35:28.000000000 +0100
+++ step2/include/asm-sh/system.h 2005-01-27 21:17:55.000000000 +0100
@@ -259,4 +259,6 @@ static __inline__ unsigned long __xchg(u
void disable_hlt(void);
void enable_hlt(void);

+#define arch_align_stack(x) (x)
+
#endif
diff -purN step1/include/asm-sh64/system.h step2/include/asm-sh64/system.h
--- step1/include/asm-sh64/system.h 2004-12-24 22:35:15.000000000 +0100
+++ step2/include/asm-sh64/system.h 2005-01-27 21:17:51.000000000 +0100
@@ -191,4 +191,6 @@ extern void print_seg(char *file,int lin

#define PL() printk("@ <%s,%s:%d>\n",__FILE__,__FUNCTION__,__LINE__)

+#define arch_align_stack(x) (x)
+
#endif /* __ASM_SH64_SYSTEM_H */
diff -purN step1/include/asm-sparc/system.h step2/include/asm-sparc/system.h
--- step1/include/asm-sparc/system.h 2004-12-24 22:35:23.000000000 +0100
+++ step2/include/asm-sparc/system.h 2005-01-27 21:18:04.000000000 +0100
@@ -257,4 +257,6 @@ extern void die_if_kernel(char *str, str

#endif /* __ASSEMBLY__ */

+#define arch_align_stack(x) (x)
+
#endif /* !(__SPARC_SYSTEM_H) */
diff -purN step1/include/asm-sparc64/system.h step2/include/asm-sparc64/system.h
--- step1/include/asm-sparc64/system.h 2004-12-24 22:33:48.000000000 +0100
+++ step2/include/asm-sparc64/system.h 2005-01-27 21:17:59.000000000 +0100
@@ -337,4 +337,6 @@ __cmpxchg(volatile void *ptr, unsigned l

#endif /* !(__ASSEMBLY__) */

+#define arch_align_stack(x) (x)
+
#endif /* !(__SPARC64_SYSTEM_H) */
diff -purN step1/include/asm-v850/system.h step2/include/asm-v850/system.h
--- step1/include/asm-v850/system.h 2004-12-24 22:35:23.000000000 +0100
+++ step2/include/asm-v850/system.h 2005-01-27 21:18:11.000000000 +0100
@@ -106,6 +106,9 @@ extern inline unsigned long __xchg (unsi
local_irq_restore (flags);

return tmp;
+
}

+#define arch_align_stack(x) (x)
+
#endif /* __V850_SYSTEM_H__ */
diff -purN step1/include/asm-x86_64/system.h step2/include/asm-x86_64/system.h
--- step1/include/asm-x86_64/system.h 2005-01-26 18:24:39.000000000 +0100
+++ step2/include/asm-x86_64/system.h 2005-01-27 21:13:49.000000000 +0100
@@ -338,4 +338,6 @@ void enable_hlt(void);
#define HAVE_EAT_KEY
void eat_key(void);

+extern unsigned long arch_align_stack(unsigned long sp);
+
#endif
-
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