--- 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/mm_types.h>
#include <linux/smp.h>
static inline void fill_ldt(struct desc_struct *desc, const struct user_desc *info)
@@ -97,6 +98,9 @@ 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)
#define write_gdt_entry(dt, entry, desc, type) native_write_gdt_entry(dt, entry, desc, type)
@@ -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 */
--- a/arch/x86/include/asm/mmu.h
+++ b/arch/x86/include/asm/mmu.h
@@ -7,6 +7,9 @@
/*
* 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;
@@ -19,6 +22,11 @@ typedef struct {
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
--- 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);
--- 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
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -802,6 +802,22 @@ 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);
+#ifdef CONFIG_X86_32
+ /*
+ * 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 (!disable_nx) {
+#ifdef CONFIG_X86_PAE
+ if (!test_cpu_cap(c, X86_FEATURE_NX))
+#endif
+ clear_cpu_cap(c, X86_FEATURE_SEP);
+ }
+#endif
+
/* If the model name is still unset, do table lookup. */
if (!c->x86_model_id[0]) {
const char *p;
--- 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,
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -243,7 +243,10 @@ 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;
regs->ds = __USER_DS;
regs->es = __USER_DS;
@@ -252,6 +255,11 @@ 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
*/
@@ -311,6 +319,9 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
if (preload_fpu)
prefetch(next->fpu.state);
+ if (next_p->mm)
+ load_user_cs_desc(cpu, next_p->mm);
+
/*
* Reload esp0.
*/
@@ -404,3 +415,40 @@ 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);
+}
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -109,6 +109,78 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)
dec_preempt_count();
}
+#ifdef CONFIG_X86_32
+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->mm);
+ 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
do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
long error_code, siginfo_t *info)
@@ -265,6 +337,29 @@ 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;
@@ -792,19 +887,37 @@ 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
--- 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>
@@ -6,7 +6,7 @@
#include <asm/pgtable.h>
#include <asm/proto.h>
-static int disable_nx __cpuinitdata;
+int disable_nx __cpuinitdata;
/*
* noexec = on|off
@@ -40,6 +42,10 @@ void __cpuinit x86_configure_nx(void)
void __init x86_report_nx(void)
{
if (!cpu_has_nx) {
+ if (!disable_nx)
+ printk(KERN_INFO "Using x86 segment limits to approximate NX protection\n");
+ else
+
printk(KERN_NOTICE "Notice: NX (Execute Disable) protection "
"missing in CPU!\n");
} else {
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -6,6 +6,7 @@
#include <linux/module.h>
#include <linux/cpu.h>
+#include <asm/desc.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/cache.h>
@@ -131,6 +132,12 @@ 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.
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -335,6 +335,24 @@ 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;
@@ -961,6 +979,9 @@ 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,
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -717,6 +722,15 @@ 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 (disable_nx || executable_stack != EXSTACK_DISABLE_X || (__supported_pte_mask & _PAGE_NX))
+ 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;
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -101,6 +101,9 @@ struct bio_list;
struct perf_event_context;
struct blk_plug;
+extern int disable_nx;
+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.
--- b/mm/mmap.c
+++ b/mm/mmap.c
@@ -44,6 +45,18 @@
#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);
@@ -432,6 +432,8 @@ __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
struct vm_area_struct *prev, struct rb_node **rb_link,
struct rb_node *rb_parent)
{
+ if (vma->vm_flags & VM_EXEC)
+ arch_add_exec_range(mm, vma->vm_end);
__vma_link_list(mm, vma, prev, rb_parent);
__vma_link_rb(mm, vma, rb_link, rb_parent);
}
@@ -489,6 +504,8 @@
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);
}
/*
@@ -790,6 +807,8 @@
} else /* cases 2, 5, 7 */
err = 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);
if (err)
return NULL;
return prev;
@@ -1966,10 +2075,14 @@
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;
+
err = 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
err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
/* Success. */
@@ -2254,6 +2367,7 @@
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,
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -25,9 +25,14 @@
#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)
{
@@ -138,7 +143,7 @@ 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;
@@ -203,6 +208,9 @@ 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);