Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2002 Jeff Dike (jdike@karaya.com) |
| 3 | * Licensed under the GPL |
| 4 | */ |
| 5 | |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 6 | #include "linux/config.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | #include "linux/sched.h" |
| 8 | #include "linux/list.h" |
| 9 | #include "linux/spinlock.h" |
| 10 | #include "linux/slab.h" |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 11 | #include "linux/errno.h" |
| 12 | #include "linux/mm.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 13 | #include "asm/current.h" |
| 14 | #include "asm/segment.h" |
| 15 | #include "asm/mmu.h" |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 16 | #include "asm/pgalloc.h" |
| 17 | #include "asm/pgtable.h" |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame^] | 18 | #include "asm/ldt.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 19 | #include "os.h" |
| 20 | #include "skas.h" |
| 21 | |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 22 | extern int __syscall_stub_start; |
| 23 | |
| 24 | static int init_stub_pte(struct mm_struct *mm, unsigned long proc, |
| 25 | unsigned long kernel) |
| 26 | { |
| 27 | pgd_t *pgd; |
| 28 | pud_t *pud; |
| 29 | pmd_t *pmd; |
| 30 | pte_t *pte; |
| 31 | |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 32 | pgd = pgd_offset(mm, proc); |
| 33 | pud = pud_alloc(mm, pgd, proc); |
| 34 | if (!pud) |
| 35 | goto out; |
| 36 | |
| 37 | pmd = pmd_alloc(mm, pud, proc); |
| 38 | if (!pmd) |
| 39 | goto out_pmd; |
| 40 | |
| 41 | pte = pte_alloc_map(mm, pmd, proc); |
| 42 | if (!pte) |
| 43 | goto out_pte; |
| 44 | |
| 45 | /* There's an interaction between the skas0 stub pages, stack |
| 46 | * randomization, and the BUG at the end of exit_mmap. exit_mmap |
| 47 | * checks that the number of page tables freed is the same as had |
| 48 | * been allocated. If the stack is on the last page table page, |
| 49 | * then the stack pte page will be freed, and if not, it won't. To |
| 50 | * avoid having to know where the stack is, or if the process mapped |
| 51 | * something at the top of its address space for some other reason, |
| 52 | * we set TASK_SIZE to end at the start of the last page table. |
| 53 | * This keeps exit_mmap off the last page, but introduces a leak |
| 54 | * of that page. So, we hang onto it here and free it in |
| 55 | * destroy_context_skas. |
| 56 | */ |
| 57 | |
| 58 | mm->context.skas.last_page_table = pmd_page_kernel(*pmd); |
Jeff Dike | 7ef9390 | 2005-09-03 15:57:52 -0700 | [diff] [blame] | 59 | #ifdef CONFIG_3_LEVEL_PGTABLES |
| 60 | mm->context.skas.last_pmd = (unsigned long) __va(pud_val(*pud)); |
| 61 | #endif |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 62 | |
| 63 | *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT)); |
| 64 | *pte = pte_mkexec(*pte); |
| 65 | *pte = pte_wrprotect(*pte); |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 66 | return(0); |
| 67 | |
| 68 | out_pmd: |
| 69 | pud_free(pud); |
| 70 | out_pte: |
| 71 | pmd_free(pmd); |
| 72 | out: |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 73 | return(-ENOMEM); |
| 74 | } |
| 75 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 76 | int init_new_context_skas(struct task_struct *task, struct mm_struct *mm) |
| 77 | { |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame^] | 78 | struct mmu_context_skas *from_mm = NULL; |
| 79 | struct mmu_context_skas *to_mm = &mm->context.skas; |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 80 | unsigned long stack = 0; |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame^] | 81 | int from_fd, ret = -ENOMEM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 82 | |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame^] | 83 | if(skas_needs_stub){ |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 84 | stack = get_zeroed_page(GFP_KERNEL); |
| 85 | if(stack == 0) |
| 86 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 87 | |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 88 | /* This zeros the entry that pgd_alloc didn't, needed since |
| 89 | * we are about to reinitialize it, and want mm.nr_ptes to |
| 90 | * be accurate. |
| 91 | */ |
| 92 | mm->pgd[USER_PTRS_PER_PGD] = __pgd(0); |
| 93 | |
| 94 | ret = init_stub_pte(mm, CONFIG_STUB_CODE, |
| 95 | (unsigned long) &__syscall_stub_start); |
| 96 | if(ret) |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 97 | goto out_free; |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 98 | |
| 99 | ret = init_stub_pte(mm, CONFIG_STUB_DATA, stack); |
| 100 | if(ret) |
| 101 | goto out_free; |
| 102 | |
| 103 | mm->nr_ptes--; |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 104 | } |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame^] | 105 | |
| 106 | to_mm->id.stack = stack; |
| 107 | if(current->mm != NULL && current->mm != &init_mm) |
| 108 | from_mm = ¤t->mm->context.skas; |
Bodo Stroesser | 9786a8f | 2005-07-07 17:56:50 -0700 | [diff] [blame] | 109 | |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 110 | if(proc_mm){ |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame^] | 111 | if(from_mm) |
| 112 | from_fd = from_mm->id.u.mm_fd; |
| 113 | else from_fd = -1; |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 114 | |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame^] | 115 | ret = new_mm(from_fd, stack); |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 116 | if(ret < 0){ |
| 117 | printk("init_new_context_skas - new_mm failed, " |
| 118 | "errno = %d\n", ret); |
| 119 | goto out_free; |
| 120 | } |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame^] | 121 | to_mm->id.u.mm_fd = ret; |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 122 | } |
| 123 | else { |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame^] | 124 | if(from_mm) |
| 125 | to_mm->id.u.pid = copy_context_skas0(stack, |
| 126 | from_mm->id.u.pid); |
| 127 | else to_mm->id.u.pid = start_userspace(stack); |
| 128 | } |
| 129 | |
| 130 | ret = init_new_ldt(to_mm, from_mm); |
| 131 | if(ret < 0){ |
| 132 | printk("init_new_context_skas - init_ldt" |
| 133 | " failed, errno = %d\n", ret); |
| 134 | goto out_free; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 135 | } |
| 136 | |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 137 | return 0; |
| 138 | |
| 139 | out_free: |
Bodo Stroesser | 858259c | 2005-11-07 00:58:55 -0800 | [diff] [blame^] | 140 | if(to_mm->id.stack != 0) |
| 141 | free_page(to_mm->id.stack); |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 142 | out: |
| 143 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 144 | } |
| 145 | |
| 146 | void destroy_context_skas(struct mm_struct *mm) |
| 147 | { |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 148 | struct mmu_context_skas *mmu = &mm->context.skas; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 149 | |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 150 | if(proc_mm) |
| 151 | os_close_file(mmu->id.u.mm_fd); |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 152 | else |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 153 | os_kill_ptraced_process(mmu->id.u.pid, 1); |
Bodo Stroesser | 8b51304 | 2005-09-03 15:57:49 -0700 | [diff] [blame] | 154 | |
| 155 | if(!proc_mm || !ptrace_faultinfo){ |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 156 | free_page(mmu->id.stack); |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 157 | pte_lock_deinit(virt_to_page(mmu->last_page_table)); |
Jeff Dike | 7ef9390 | 2005-09-03 15:57:52 -0700 | [diff] [blame] | 158 | pte_free_kernel((pte_t *) mmu->last_page_table); |
| 159 | dec_page_state(nr_page_table_pages); |
| 160 | #ifdef CONFIG_3_LEVEL_PGTABLES |
| 161 | pmd_free((pmd_t *) mmu->last_pmd); |
| 162 | #endif |
Jeff Dike | d67b569 | 2005-07-07 17:56:49 -0700 | [diff] [blame] | 163 | } |
| 164 | } |