diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index e8de2f6..538c2b6 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -5,6 +5,7 @@
#include <asm/ldt.h>
#include <asm/mmu.h>
#include <linux/smp.h>
+#include <linux/mm_types.h>
static inline void fill_ldt(struct desc_struct *desc,
const struct user_desc *info)
@@ -93,6 +94,9 @@ static inline int desc_empty(const void *ptr)
#define load_TLS(t, cpu) native_load_tls(t, cpu)
#define set_ldt native_set_ldt
+#ifdef CONFIG_X86_32
+#define load_user_cs_desc native_load_user_cs_desc
+#endif /*CONFIG_X86_32*/
#define write_ldt_entry(dt, entry, desc) \
native_write_ldt_entry(dt, entry, desc)
@@ -392,4 +396,25 @@ static inline void set_system_intr_gate_ist(int n, void *addr, unsigned ist)
_set_gate(n, GATE_INTERRUPT, addr, 0x3, ist, __KERNEL_CS);
}
+#ifdef CONFIG_X86_32
+static inline void set_user_cs(struct desc_struct *desc, unsigned long limit)
+{
+ limit = (limit - 1) / PAGE_SIZE;
+ desc->a = limit & 0xffff;
+ desc->b = (limit & 0xf0000) | 0x00c0fb00;
+}
+
+static inline void native_load_user_cs_desc(int cpu, struct mm_struct *mm)
+{
+ get_cpu_gdt_table(cpu)[GDT_ENTRY_DEFAULT_USER_CS] = (mm)->context.user_cs;
+}
+
+#define arch_add_exec_range arch_add_exec_range
+#define arch_remove_exec_range arch_remove_exec_range
+#define arch_flush_exec_range arch_flush_exec_range
+extern void arch_add_exec_range(struct mm_struct *mm, unsigned long limit);
+extern void arch_remove_exec_range(struct mm_struct *mm, unsigned long limit);
+extern void arch_flush_exec_range(struct mm_struct *mm);
+#endif /* CONFIG_X86_32 */
+
#endif /* _ASM_X86_DESC_H */
diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
index 80a1dee..8314c66 100644
--- a/arch/x86/include/asm/mmu.h
+++ b/arch/x86/include/asm/mmu.h
@@ -7,12 +7,19 @@
/*
* The x86 doesn't have a mmu context, but
* we put the segment information here.
+ *
+ * exec_limit is used to track the range PROT_EXEC
+ * mappings span.
*/
typedef struct {
void *ldt;
int size;
struct mutex lock;
void *vdso;
+#ifdef CONFIG_X86_32
+ struct desc_struct user_cs;
+ unsigned long exec_limit;
+#endif
} mm_context_t;
#ifdef CONFIG_SMP
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 8aebcc4..cbbd2b0 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -289,6 +289,12 @@ static inline void set_ldt(const void *addr, unsigned entries)
{
PVOP_VCALL2(pv_cpu_ops.set_ldt, addr, entries);
}
+#ifdef CONFIG_X86_32
+static inline void load_user_cs_desc(unsigned int cpu, struct mm_struct *mm)
+{
+ PVOP_VCALL2(pv_cpu_ops.load_user_cs_desc, cpu, mm);
+}
+#endif /*CONFIG_X86_32*/
static inline void store_gdt(struct desc_ptr *dtr)
{
PVOP_VCALL1(pv_cpu_ops.store_gdt, dtr);
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index dd0f5b3..c2727ef 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -118,6 +118,9 @@ struct pv_cpu_ops {
void (*store_gdt)(struct desc_ptr *);
void (*store_idt)(struct desc_ptr *);
void (*set_ldt)(const void *desc, unsigned entries);
+#ifdef CONFIG_X86_32
+ void (*load_user_cs_desc)(int cpu, struct mm_struct *mm);
+#endif
unsigned long (*store_tr)(void);
void (*load_tls)(struct thread_struct *t, unsigned int cpu);
#ifdef CONFIG_X86_64
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index c3429e8..62cc460 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -161,6 +161,9 @@ static inline int hlt_works(int cpu)
#define cache_line_size() (boot_cpu_data.x86_cache_alignment)
+#define __HAVE_ARCH_ALIGN_STACK
+extern unsigned long arch_align_stack(unsigned long sp);
+
extern void cpu_detect(struct cpuinfo_x86 *c);
extern struct pt_regs *idle_regs(struct pt_regs *);
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index cc25c2b..6ce4863 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -798,6 +798,20 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
/* Filter out anything that depends on CPUID levels we don't have */
filter_cpuid_features(c, true);
+ /*
+ * emulation of NX with segment limits unfortunately means
+ * we have to disable the fast system calls, due to the way that
+ * sysexit clears the segment limits on return.
+ * If we have either disabled exec-shield on the boot command line,
+ * or we have NX, then we don't need to do this.
+ */
+ if (exec_shield != 0) {
+#ifdef CONFIG_X86_PAE
+ if (!test_cpu_cap(c, X86_FEATURE_NX))
+#endif
+ clear_cpu_cap(c, X86_FEATURE_SEP);
+ }
+
/* If the model name is still unset, do table lookup. */
if (!c->x86_model_id[0]) {
const char *p;
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 1b1739d..c2dda16 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -345,6 +345,9 @@ struct pv_cpu_ops pv_cpu_ops = {
.read_tscp = native_read_tscp,
.load_tr_desc = native_load_tr_desc,
.set_ldt = native_set_ldt,
+#ifdef CONFIG_X86_32
+ .load_user_cs_desc = native_load_user_cs_desc,
+#endif /*CONFIG_X86_32*/
.load_gdt = native_load_gdt,
.load_idt = native_load_idt,
.store_gdt = native_store_gdt,
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 4cf7956..b2407dc 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -296,7 +296,10 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
void
start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
{
+ int cpu;
+
set_user_gs(regs, 0);
+
regs->fs = 0;
set_fs(USER_DS);
regs->ds = __USER_DS;
@@ -305,6 +308,11 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
regs->cs = __USER_CS;
regs->ip = new_ip;
regs->sp = new_sp;
+
+ cpu = get_cpu();
+ load_user_cs_desc(cpu, current->mm);
+ put_cpu();
+
/*
* Free the old FP and other extended state
*/
@@ -364,6 +372,9 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
if (preload_fpu)
prefetch(next->xstate);
+ if (next_p->mm)
+ load_user_cs_desc(cpu, next_p->mm);
+
/*
* Reload esp0.
*/
@@ -497,3 +508,40 @@ unsigned long get_wchan(struct task_struct *p)
return 0;
}
+static void modify_cs(struct mm_struct *mm, unsigned long limit)
+{
+ mm->context.exec_limit = limit;
+ set_user_cs(&mm->context.user_cs, limit);
+ if (mm == current->mm) {
+ int cpu;
+
+ cpu = get_cpu();
+ load_user_cs_desc(cpu, mm);
+ put_cpu();
+ }
+}
+
+void arch_add_exec_range(struct mm_struct *mm, unsigned long limit)
+{
+ if (limit > mm->context.exec_limit)
+ modify_cs(mm, limit);
+}
+
+void arch_remove_exec_range(struct mm_struct *mm, unsigned long old_end)
+{
+ struct vm_area_struct *vma;
+ unsigned long limit = PAGE_SIZE;
+
+ if (old_end == mm->context.exec_limit) {
+ for (vma = mm->mmap; vma; vma = vma->vm_next)
+ if ((vma->vm_flags & VM_EXEC) && (vma->vm_end > limit))
+ limit = vma->vm_end;
+ modify_cs(mm, limit);
+ }
+}
+
+void arch_flush_exec_range(struct mm_struct *mm)
+{
+ mm->context.exec_limit = 0;
+ set_user_cs(&mm->context.user_cs, 0);
+}
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 7e37dce..92ae538 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -115,6 +115,76 @@ die_if_kernel(const char *str, struct pt_regs *regs, long err)
if (!user_mode_vm(regs))
die(str, regs, err);
}
+
+static inline int
+__compare_user_cs_desc(const struct desc_struct *desc1,
+ const struct desc_struct *desc2)
+{
+ return ((desc1->limit0 != desc2->limit0) ||
+ (desc1->limit != desc2->limit) ||
+ (desc1->base0 != desc2->base0) ||
+ (desc1->base1 != desc2->base1) ||
+ (desc1->base2 != desc2->base2));
+}
+
+/*
+ * lazy-check for CS validity on exec-shield binaries:
+ *
+ * the original non-exec stack patch was written by
+ * Solar Designer <solar at openwall.com>. Thanks!
+ */
+static int
+check_lazy_exec_limit(int cpu, struct pt_regs *regs, long error_code)
+{
+ struct desc_struct *desc1, *desc2;
+ struct vm_area_struct *vma;
+ unsigned long limit;
+
+ if (current->mm == NULL)
+ return 0;
+
+ limit = -1UL;
+ if (current->mm->context.exec_limit != -1UL) {
+ limit = PAGE_SIZE;
+ spin_lock(¤t->mm->page_table_lock);
+ for (vma = current->mm->mmap; vma; vma = vma->vm_next)
+ if ((vma->vm_flags & VM_EXEC) && (vma->vm_end > limit))
+ limit = vma->vm_end;
+ vma = get_gate_vma(current);
+ if (vma && (vma->vm_flags & VM_EXEC) && (vma->vm_end > limit))
+ limit = vma->vm_end;
+ spin_unlock(¤t->mm->page_table_lock);
+ if (limit >= TASK_SIZE)
+ limit = -1UL;
+ current->mm->context.exec_limit = limit;
+ }
+ set_user_cs(¤t->mm->context.user_cs, limit);
+
+ desc1 = ¤t->mm->context.user_cs;
+ desc2 = get_cpu_gdt_table(cpu) + GDT_ENTRY_DEFAULT_USER_CS;
+
+ if (__compare_user_cs_desc(desc1, desc2)) {
+ /*
+ * The CS was not in sync - reload it and retry the
+ * instruction. If the instruction still faults then
+ * we won't hit this branch next time around.
+ */
+ if (print_fatal_signals >= 2) {
+ printk(KERN_ERR "#GPF fixup (%ld[seg:%lx]) at %08lx, CPU#%d.\n",
+ error_code, error_code/8, regs->ip,
+ smp_processor_id());
+ printk(KERN_ERR "exec_limit: %08lx, user_cs: %08x/%08x, CPU_cs: %08x/%08x.\n",
+ current->mm->context.exec_limit,
+ desc1->a, desc1->b, desc2->a, desc2->b);
+ }
+
+ load_user_cs_desc(cpu, current->mm);
+
+ return 1;
+ }
+
+ return 0;
+}
#endif
static void __kprobes
@@ -273,6 +343,29 @@ do_general_protection(struct pt_regs *regs, long error_code)
if (!user_mode(regs))
goto gp_in_kernel;
+#ifdef CONFIG_X86_32
+{
+ int cpu;
+ int ok;
+
+ cpu = get_cpu();
+ ok = check_lazy_exec_limit(cpu, regs, error_code);
+ put_cpu();
+
+ if (ok)
+ return;
+
+ if (print_fatal_signals) {
+ printk(KERN_ERR "#GPF(%ld[seg:%lx]) at %08lx, CPU#%d.\n",
+ error_code, error_code/8, regs->ip, smp_processor_id());
+ printk(KERN_ERR "exec_limit: %08lx, user_cs: %08x/%08x.\n",
+ current->mm->context.exec_limit,
+ current->mm->context.user_cs.a,
+ current->mm->context.user_cs.b);
+ }
+}
+#endif /*CONFIG_X86_32*/
+
tsk->thread.error_code = error_code;
tsk->thread.trap_no = 13;
@@ -881,19 +974,37 @@ do_device_not_available(struct pt_regs *regs, long error_code)
}
#ifdef CONFIG_X86_32
+/*
+ * The fixup code for errors in iret jumps to here (iret_exc). It loses
+ * the original trap number and erorr code. The bogus trap 32 and error
+ * code 0 are what the vanilla kernel delivers via:
+ * DO_ERROR_INFO(32, SIGSEGV, "iret exception", iret_error, ILL_BADSTK, 0, 1)
+ *
+ * NOTE: Because of the final "1" in the macro we need to enable interrupts.
+ *
+ * In case of a general protection fault in the iret instruction, we
+ * need to check for a lazy CS update for exec-shield.
+ */
dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
{
- siginfo_t info;
+ int ok;
+ int cpu;
+
local_irq_enable();
- info.si_signo = SIGILL;
- info.si_errno = 0;
- info.si_code = ILL_BADSTK;
- info.si_addr = NULL;
- if (notify_die(DIE_TRAP, "iret exception",
- regs, error_code, 32, SIGILL) == NOTIFY_STOP)
- return;
- do_trap(32, SIGILL, "iret exception", regs, error_code, &info);
+ cpu = get_cpu();
+ ok = check_lazy_exec_limit(cpu, regs, error_code);
+ put_cpu();
+
+ if (!ok && notify_die(DIE_TRAP, "iret exception", regs,
+ error_code, 32, SIGSEGV) != NOTIFY_STOP) {
+ siginfo_t info;
+ info.si_signo = SIGSEGV;
+ info.si_errno = 0;
+ info.si_code = ILL_BADSTK;
+ info.si_addr = 0;
+ do_trap(32, SIGSEGV, "iret exception", regs, error_code, &info);
+ }
}
#endif
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 73ffd55..0cf2a7b 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -149,6 +149,12 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
set_nx();
if (nx_enabled)
printk(KERN_INFO "NX (Execute Disable) protection: active\n");
+#ifdef CONFIG_X86_32
+ else
+ if (exec_shield)
+ printk(KERN_INFO "Using x86 segment limits to approximate "
+ "NX protection\n");
+#endif
/* Enable PSE if available */
if (cpu_has_pse)
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index c8191de..7d84d01 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -124,13 +124,16 @@ static unsigned long mmap_legacy_base(void)
*/
void arch_pick_mmap_layout(struct mm_struct *mm)
{
- if (mmap_is_legacy()) {
+ if (!(2 & exec_shield) && mmap_is_legacy()) {
mm->mmap_base = mmap_legacy_base();
mm->get_unmapped_area = arch_get_unmapped_area;
mm->unmap_area = arch_unmap_area;
} else {
mm->mmap_base = mmap_base();
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
+ if (!(current->personality & READ_IMPLIES_EXEC)
+ && mmap_is_ia32())
+ mm->get_unmapped_exec_area = arch_get_unmapped_exec_area;
mm->unmap_area = arch_unmap_area_topdown;
}
}
diff --git a/arch/x86/mm/setup_nx.c b/arch/x86/mm/setup_nx.c
index 513d8ed..c614a90 100644
--- a/arch/x86/mm/setup_nx.c
+++ b/arch/x86/mm/setup_nx.c
@@ -1,3 +1,4 @@
+#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/init.h>
@@ -27,6 +28,9 @@ static int __init noexec_setup(char *str)
} else if (!strncmp(str, "off", 3)) {
disable_nx = 1;
__supported_pte_mask &= ~_PAGE_NX;
+#ifdef CONFIG_X86_32
+ exec_shield = 0;
+#endif
}
return 0;
}
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 36fe08e..3806a45 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -6,6 +6,7 @@
#include <linux/interrupt.h>
#include <linux/module.h>
+#include <asm/desc.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/apic.h>
@@ -130,6 +131,12 @@ void smp_invalidate_interrupt(struct pt_regs *regs)
union smp_flush_state *f;
cpu = smp_processor_id();
+
+#ifdef CONFIG_X86_32
+ if (current->active_mm)
+ load_user_cs_desc(cpu, current->active_mm);
+#endif
+
/*
* orig_rax contains the negated interrupt vector.
* Use that to determine where the sender put the data.
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index 58bc00f..1fdafb5 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -331,7 +331,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
if (compat)
addr = VDSO_HIGH_BASE;
else {
- addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
+ addr = get_unmapped_area_prot(NULL, 0, PAGE_SIZE, 0, 0, 1);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 3439616..31e5c6f 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -323,6 +323,24 @@ static void xen_set_ldt(const void *addr, unsigned entries)
xen_mc_issue(PARAVIRT_LAZY_CPU);
}
+#ifdef CONFIG_X86_32
+static void xen_load_user_cs_desc(int cpu, struct mm_struct *mm)
+{
+ void *gdt;
+ xmaddr_t mgdt;
+ u64 descriptor;
+ struct desc_struct user_cs;
+
+ gdt = &get_cpu_gdt_table(cpu)[GDT_ENTRY_DEFAULT_USER_CS];
+ mgdt = virt_to_machine(gdt);
+
+ user_cs = mm->context.user_cs;
+ descriptor = (u64) user_cs.a | ((u64) user_cs.b) << 32;
+
+ HYPERVISOR_update_descriptor(mgdt.maddr, descriptor);
+}
+#endif /*CONFIG_X86_32*/
+
static void xen_load_gdt(const struct desc_ptr *dtr)
{
unsigned long va = dtr->address;
@@ -949,6 +967,9 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = {
.load_tr_desc = paravirt_nop,
.set_ldt = xen_set_ldt,
+#ifdef CONFIG_X86_32
+ .load_user_cs_desc = xen_load_user_cs_desc,
+#endif /*CONFIG_X86_32*/
.load_gdt = xen_load_gdt,
.load_idt = xen_load_idt,
.load_tls = xen_load_tls,
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index b9b3bb5..1e55926 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -73,7 +73,7 @@ static struct linux_binfmt elf_format = {
.hasvdso = 1
};
-#define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)
+#define BAD_ADDR(x) IS_ERR_VALUE(x)
static int set_brk(unsigned long start, unsigned long end)
{
@@ -721,6 +721,11 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
break;
}
+ if (current->personality == PER_LINUX && (exec_shield & 2)) {
+ executable_stack = EXSTACK_DISABLE_X;
+ current->flags |= PF_RANDOMIZE;
+ }
+
/* Some simple consistency checks for the interpreter */
if (elf_interpreter) {
retval = -ELIBBAD;
@@ -740,6 +745,15 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
if (retval)
goto out_free_dentry;
+#ifdef CONFIG_X86_32
+ /*
+ * Turn off the CS limit completely if exec-shield disabled or
+ * NX active:
+ */
+ if (!exec_shield || executable_stack != EXSTACK_DISABLE_X || nx_enabled)
+ arch_add_exec_range(current->mm, -1);
+#endif
+
/* OK, This is the point of no return */
current->flags &= ~PF_FORKNOEXEC;
current->mm->def_flags = def_flags;
@@ -747,7 +761,8 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
/* Do this immediately, since STACK_TOP as used in setup_arg_pages
may depend on the personality. */
SET_PERSONALITY(loc->elf_ex);
- if (elf_read_implies_exec(loc->elf_ex, executable_stack))
+ if (!(exec_shield & 2) &&
+ elf_read_implies_exec(loc->elf_ex, executable_stack))
current->personality |= READ_IMPLIES_EXEC;
if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
@@ -912,7 +927,7 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
interpreter,
&interp_map_addr,
load_bias);
- if (!IS_ERR((void *)elf_entry)) {
+ if (!BAD_ADDR(elf_entry)) {
/*
* load_elf_interp() returns relocation
* adjustment
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 24c3956..88f944d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1129,7 +1129,13 @@ extern int install_special_mapping(struct mm_struct *mm,
unsigned long addr, unsigned long len,
unsigned long flags, struct page **pages);
-extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
+extern unsigned long get_unmapped_area_prot(struct file *, unsigned long, unsigned long, unsigned long, unsigned long, int);
+
+static inline unsigned long get_unmapped_area(struct file *file, unsigned long addr,
+ unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+ return get_unmapped_area_prot(file, addr, len, pgoff, flags, 0);
+}
extern unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot,
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 84a524a..a81e0db 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -206,6 +206,9 @@ struct mm_struct {
unsigned long (*get_unmapped_area) (struct file *filp,
unsigned long addr, unsigned long len,
unsigned long pgoff, unsigned long flags);
+ unsigned long (*get_unmapped_exec_area) (struct file *filp,
+ unsigned long addr, unsigned long len,
+ unsigned long pgoff, unsigned long flags);
void (*unmap_area) (struct mm_struct *mm, unsigned long addr);
unsigned long mmap_base; /* base of mmap area */
unsigned long task_size; /* size of task vm space */
diff --git a/include/linux/resource.h b/include/linux/resource.h
index 40fc7e6..68c2549 100644
--- a/include/linux/resource.h
+++ b/include/linux/resource.h
@@ -55,8 +55,11 @@ struct rlimit {
/*
* Limit the stack by to some sane default: root can always
* increase this limit if needed.. 8MB seems reasonable.
+ *
+ * (2MB more to cover randomization effects.)
*/
-#define _STK_LIM (8*1024*1024)
+#define _STK_LIM (10*1024*1024)
+#define EXEC_STACK_BIAS (2*1024*1024)
/*
* GPG2 wants 64kB of mlocked memory, to make sure pass phrases
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 75e6e60..0bce489 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -102,6 +102,9 @@ struct fs_struct;
struct bts_context;
struct perf_event_context;
+extern int exec_shield;
+extern int print_fatal_signals;
+
/*
* List of flags we want to share for kernel threads,
* if only because they are not used by them anyway.
@@ -378,6 +381,10 @@ extern int sysctl_max_map_count;
extern unsigned long
arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
unsigned long, unsigned long);
+
+extern unsigned long
+arch_get_unmapped_exec_area(struct file *, unsigned long, unsigned long,
+ unsigned long, unsigned long);
extern unsigned long
arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
unsigned long len, unsigned long pgoff,
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 0d949c5..12ca319 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -88,6 +88,26 @@ extern int sysctl_nr_open_min, sysctl_nr_open_max;
#ifndef CONFIG_MMU
extern int sysctl_nr_trim_pages;
#endif
+
+int exec_shield = (1<<0);
+/* exec_shield is a bitmask:
+ * 0: off; vdso at STACK_TOP, 1 page below TASK_SIZE
+ * (1<<0) 1: on [also on if !=0]
+ * (1<<1) 2: force noexecstack regardless of PT_GNU_STACK
+ * The old settings
+ * (1<<2) 4: vdso just below .text of main (unless too low)
+ * (1<<3) 8: vdso just below .text of PT_INTERP (unless too low)
+ * are ignored because the vdso is placed completely randomly
+ */
+
+static int __init setup_exec_shield(char *str)
+{
+ get_option(&str, &exec_shield);
+
+ return 1;
+}
+__setup("exec-shield=", setup_exec_shield);
+
#ifdef CONFIG_RCU_TORTURE_TEST
extern int rcutorture_runnable;
#endif /* #ifdef CONFIG_RCU_TORTURE_TEST */
@@ -408,6 +428,14 @@ static struct ctl_table kern_table[] = {
.proc_handler = &proc_dointvec,
},
{
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "exec-shield",
+ .data = &exec_shield,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+ {
.ctl_name = KERN_CORE_USES_PID,
.procname = "core_uses_pid",
.data = &core_uses_pid,
diff --git a/mm/mmap.c b/mm/mmap.c
index 73f5e4b..814b95f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -29,6 +29,7 @@
#include <linux/rmap.h>
#include <linux/mmu_notifier.h>
#include <linux/perf_event.h>
+#include <linux/random.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -45,6 +46,18 @@
#define arch_rebalance_pgtables(addr, len) (addr)
#endif
+/* No sane architecture will #define these to anything else */
+#ifndef arch_add_exec_range
+#define arch_add_exec_range(mm, limit) do { ; } while (0)
+#endif
+#ifndef arch_flush_exec_range
+#define arch_flush_exec_range(mm) do { ; } while (0)
+#endif
+#ifndef arch_remove_exec_range
+#define arch_remove_exec_range(mm, limit) do { ; } while (0)
+#endif
+
+
static void unmap_region(struct mm_struct *mm,
struct vm_area_struct *vma, struct vm_area_struct *prev,
unsigned long start, unsigned long end);
@@ -389,6 +402,9 @@ static inline void
{
struct vm_area_struct *next;
+ if (vma->vm_flags & VM_EXEC)
+ arch_add_exec_range(mm, vma->vm_end);
+
vma->vm_prev = prev;
if (prev) {
next = prev->vm_next;
@@ -491,6 +506,8 @@ __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
rb_erase(&vma->vm_rb, &mm->mm_rb);
if (mm->mmap_cache == vma)
mm->mmap_cache = prev;
+ if (vma->vm_flags & VM_EXEC)
+ arch_remove_exec_range(mm, vma->vm_end);
}
/*
@@ -798,6 +815,8 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
} else /* cases 2, 5, 7 */
vma_adjust(prev, prev->vm_start,
end, prev->vm_pgoff, NULL);
+ if (prev->vm_flags & VM_EXEC)
+ arch_add_exec_range(mm, prev->vm_end);
return prev;
}
@@ -970,7 +989,8 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
/* Obtain the address to map to. we verify (or select) it and ensure
* that it represents a valid section of the address space.
*/
- addr = get_unmapped_area(file, addr, len, pgoff, flags);
+ addr = get_unmapped_area_prot(file, addr, len, pgoff, flags,
+ prot & PROT_EXEC);
if (addr & ~PAGE_MASK)
return addr;
@@ -1453,21 +1473,25 @@ void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
}
unsigned long
-get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
- unsigned long pgoff, unsigned long flags)
+get_unmapped_area_prot(struct file *file, unsigned long addr, unsigned long len,
+ unsigned long pgoff, unsigned long flags, int exec)
{
unsigned long (*get_area)(struct file *, unsigned long,
unsigned long, unsigned long, unsigned long);
unsigned long error = arch_mmap_check(addr, len, flags);
if (error)
return error;
/* Careful about overflows.. */
if (len > TASK_SIZE)
return -ENOMEM;
- get_area = current->mm->get_unmapped_area;
+ if (exec && current->mm->get_unmapped_exec_area)
+ get_area = current->mm->get_unmapped_exec_area;
+ else
+ get_area = current->mm->get_unmapped_area;
+
if (file && file->f_op && file->f_op->get_unmapped_area)
get_area = file->f_op->get_unmapped_area;
addr = get_area(file, addr, len, pgoff, flags);
@@ -1473,8 +1497,76 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
return arch_rebalance_pgtables(addr, len);
}
+EXPORT_SYMBOL(get_unmapped_area_prot);
+
+#define SHLIB_BASE 0x00110000
+
+unsigned long
+arch_get_unmapped_exec_area(struct file *filp, unsigned long addr0,
+ unsigned long len0, unsigned long pgoff, unsigned long flags)
+{
+ unsigned long addr = addr0, len = len0;
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ unsigned long tmp;
+
+ if (len > TASK_SIZE)
+ return -ENOMEM;
+
+ if (flags & MAP_FIXED)
+ return addr;
+
+ if (!addr)
+ addr = randomize_range(SHLIB_BASE, 0x01000000, len);
+
+ if (addr) {
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr &&
+ (!vma || addr + len <= vma->vm_start))
+ return addr;
+ }
+
+ addr = SHLIB_BASE;
+ for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
+ /* At this point: (!vma || addr < vma->vm_end). */
+ if (TASK_SIZE - len < addr)
+ return -ENOMEM;
+
+ if (!vma || addr + len <= vma->vm_start) {
+ /*
+ * Must not let a PROT_EXEC mapping get into the
+ * brk area:
+ */
+ if (addr + len > mm->brk)
+ goto failed;
+
+ /*
+ * Up until the brk area we randomize addresses
+ * as much as possible:
+ */
+ if (addr >= 0x01000000) {
+ tmp = randomize_range(0x01000000,
+ PAGE_ALIGN(max(mm->start_brk,
+ (unsigned long)0x08000000)), len);
+ vma = find_vma(mm, tmp);
+ if (TASK_SIZE - len >= tmp &&
+ (!vma || tmp + len <= vma->vm_start))
+ return tmp;
+ }
+ /*
+ * Ok, randomization didnt work out - return
+ * the result of the linear search:
+ */
+ return addr;
+ }
+ addr = vma->vm_end;
+ }
+
+failed:
+ return current->mm->get_unmapped_area(filp, addr0, len0, pgoff, flags);
+}
-EXPORT_SYMBOL(get_unmapped_area);
/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
@@ -1549,6 +1641,14 @@ out:
return prev ? prev->vm_next : vma;
}
+static int over_stack_limit(unsigned long sz)
+{
+ if (sz < EXEC_STACK_BIAS)
+ return 0;
+ return (sz - EXEC_STACK_BIAS) >
+ current->signal->rlim[RLIMIT_STACK].rlim_cur;
+}
+
/*
* Verify that the stack growth is acceptable and
* update accounting. This is shared with both the
@@ -1565,7 +1665,7 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
return -ENOMEM;
/* Stack limit test */
- if (size > rlim[RLIMIT_STACK].rlim_cur)
+ if (over_stack_limit(size))
return -ENOMEM;
/* mlock limit tests */
@@ -1875,10 +1975,14 @@ int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
if (new->vm_ops && new->vm_ops->open)
new->vm_ops->open(new);
- if (new_below)
+ if (new_below) {
+ unsigned long old_end = vma->vm_end;
+
vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
((addr - new->vm_start) >> PAGE_SHIFT), new);
- else
+ if (vma->vm_flags & VM_EXEC)
+ arch_remove_exec_range(mm, old_end);
+ } else
vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
return 0;
@@ -2128,6 +2232,7 @@ void exit_mmap(struct mm_struct *mm)
free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
tlb_finish_mmu(tlb, 0, end);
+ arch_flush_exec_range(mm);
/*
* Walk the list again, actually closing and freeing it,
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 8bc969d..3c9b4fc 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -26,9 +26,14 @@
#include <linux/perf_event.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
+#ifndef arch_remove_exec_range
+#define arch_remove_exec_range(mm, limit) do { ; } while (0)
+#endif
+
#ifndef pgprot_modify
static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
{
@@ -139,7 +144,7 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
struct mm_struct *mm = vma->vm_mm;
unsigned long oldflags = vma->vm_flags;
long nrpages = (end - start) >> PAGE_SHIFT;
- unsigned long charged = 0;
+ unsigned long charged = 0, old_end = vma->vm_end;
pgoff_t pgoff;
int error;
int dirty_accountable = 0;
@@ -204,6 +209,9 @@ success:
dirty_accountable = 1;
}
+ if (oldflags & VM_EXEC)
+ arch_remove_exec_range(current->mm, old_end);
+
mmu_notifier_invalidate_range_start(mm, start, end);
if (is_vm_hugetlb_page(vma))
hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
diff --git a/mm/mremap.c b/mm/mremap.c
index 97bff25..17a9fd7 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -414,10 +414,10 @@ unsigned long do_mremap(unsigned long addr,
if (vma->vm_flags & VM_MAYSHARE)
map_flags |= MAP_SHARED;
- new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
+ new_addr = get_unmapped_area_prot(vma->vm_file, 0, new_len,
vma->vm_pgoff +
((addr - vma->vm_start) >> PAGE_SHIFT),
- map_flags);
+ map_flags, vma->vm_flags & VM_EXEC);
if (new_addr & ~PAGE_MASK) {
ret = new_addr;
goto out;