* Licensed under the GPL
*/
+#include "linux/config.h"
#include "linux/sched.h"
#include "linux/list.h"
#include "linux/spinlock.h"
#include "linux/slab.h"
+#include "linux/errno.h"
+#include "linux/mm.h"
#include "asm/current.h"
#include "asm/segment.h"
#include "asm/mmu.h"
+#include "asm/pgalloc.h"
+#include "asm/pgtable.h"
+#include "asm/ldt.h"
#include "os.h"
#include "skas.h"
+extern int __syscall_stub_start;
+
+static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
+ unsigned long kernel)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ pgd = pgd_offset(mm, proc);
+ pud = pud_alloc(mm, pgd, proc);
+ if (!pud)
+ goto out;
+
+ pmd = pmd_alloc(mm, pud, proc);
+ if (!pmd)
+ goto out_pmd;
+
+ pte = pte_alloc_map(mm, pmd, proc);
+ if (!pte)
+ goto out_pte;
+
+ /* There's an interaction between the skas0 stub pages, stack
+ * randomization, and the BUG at the end of exit_mmap. exit_mmap
+ * checks that the number of page tables freed is the same as had
+ * been allocated. If the stack is on the last page table page,
+ * then the stack pte page will be freed, and if not, it won't. To
+ * avoid having to know where the stack is, or if the process mapped
+ * something at the top of its address space for some other reason,
+ * we set TASK_SIZE to end at the start of the last page table.
+ * This keeps exit_mmap off the last page, but introduces a leak
+ * of that page. So, we hang onto it here and free it in
+ * destroy_context_skas.
+ */
+
+ mm->context.skas.last_page_table = pmd_page_kernel(*pmd);
+#ifdef CONFIG_3_LEVEL_PGTABLES
+ mm->context.skas.last_pmd = (unsigned long) __va(pud_val(*pud));
+#endif
+
+ *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
+ *pte = pte_mkexec(*pte);
+ *pte = pte_wrprotect(*pte);
+ return(0);
+
+ out_pmd:
+ pud_free(pud);
+ out_pte:
+ pmd_free(pmd);
+ out:
+ return(-ENOMEM);
+}
+
int init_new_context_skas(struct task_struct *task, struct mm_struct *mm)
{
- int from;
+ struct mmu_context_skas *from_mm = NULL;
+ struct mmu_context_skas *to_mm = &mm->context.skas;
+ unsigned long stack = 0;
+ int ret = -ENOMEM;
+
+ if(skas_needs_stub){
+ stack = get_zeroed_page(GFP_KERNEL);
+ if(stack == 0)
+ goto out;
+
+ /* This zeros the entry that pgd_alloc didn't, needed since
+ * we are about to reinitialize it, and want mm.nr_ptes to
+ * be accurate.
+ */
+ mm->pgd[USER_PTRS_PER_PGD] = __pgd(0);
- if((current->mm != NULL) && (current->mm != &init_mm))
- from = current->mm->context.skas.mm_fd;
- else from = -1;
+ ret = init_stub_pte(mm, CONFIG_STUB_CODE,
+ (unsigned long) &__syscall_stub_start);
+ if(ret)
+ goto out_free;
- mm->context.skas.mm_fd = new_mm(from);
- if(mm->context.skas.mm_fd < 0){
- printk("init_new_context_skas - new_mm failed, errno = %d\n",
- mm->context.skas.mm_fd);
- return(mm->context.skas.mm_fd);
+ ret = init_stub_pte(mm, CONFIG_STUB_DATA, stack);
+ if(ret)
+ goto out_free;
+
+ mm->nr_ptes--;
}
- return(0);
+ to_mm->id.stack = stack;
+ if(current->mm != NULL && current->mm != &init_mm)
+ from_mm = ¤t->mm->context.skas;
+
+ if(proc_mm){
+ ret = new_mm(stack);
+ if(ret < 0){
+ printk("init_new_context_skas - new_mm failed, "
+ "errno = %d\n", ret);
+ goto out_free;
+ }
+ to_mm->id.u.mm_fd = ret;
+ }
+ else {
+ if(from_mm)
+ to_mm->id.u.pid = copy_context_skas0(stack,
+ from_mm->id.u.pid);
+ else to_mm->id.u.pid = start_userspace(stack);
+ }
+
+ ret = init_new_ldt(to_mm, from_mm);
+ if(ret < 0){
+ printk("init_new_context_skas - init_ldt"
+ " failed, errno = %d\n", ret);
+ goto out_free;
+ }
+
+ return 0;
+
+ out_free:
+ if(to_mm->id.stack != 0)
+ free_page(to_mm->id.stack);
+ out:
+ return ret;
}
void destroy_context_skas(struct mm_struct *mm)
{
- os_close_file(mm->context.skas.mm_fd);
-}
+ struct mmu_context_skas *mmu = &mm->context.skas;
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only. This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
+ if(proc_mm)
+ os_close_file(mmu->id.u.mm_fd);
+ else
+ os_kill_ptraced_process(mmu->id.u.pid, 1);
+
+ if(!proc_mm || !ptrace_faultinfo){
+ free_page(mmu->id.stack);
+ pte_lock_deinit(virt_to_page(mmu->last_page_table));
+ pte_free_kernel((pte_t *) mmu->last_page_table);
+ dec_page_state(nr_page_table_pages);
+#ifdef CONFIG_3_LEVEL_PGTABLES
+ pmd_free((pmd_t *) mmu->last_pmd);
+#endif
+ }
+}
git://git.onelab.eu / linux-2.6.git / blobdiff