| 1 | /* |
| 2 | * linux/kernel/futex_compat.c |
| 3 | * |
| 4 | * Futex compatibililty routines. |
| 5 | * |
| 6 | * Copyright 2006, Red Hat, Inc., Ingo Molnar |
| 7 | */ |
| 8 | |
| 9 | #include <linux/linkage.h> |
| 10 | #include <linux/compat.h> |
| 11 | #include <linux/futex.h> |
| 12 | |
| 13 | #include <asm/uaccess.h> |
| 14 | |
| 15 | |
| 16 | /* |
| 17 | * Fetch a robust-list pointer. Bit 0 signals PI futexes: |
| 18 | */ |
| 19 | static inline int |
| 20 | fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry, |
| 21 | compat_uptr_t *head, int *pi) |
| 22 | { |
| 23 | if (get_user(*uentry, head)) |
| 24 | return -EFAULT; |
| 25 | |
| 26 | *entry = compat_ptr((*uentry) & ~1); |
| 27 | *pi = (unsigned int)(*uentry) & 1; |
| 28 | |
| 29 | return 0; |
| 30 | } |
| 31 | |
| 32 | /* |
| 33 | * Walk curr->robust_list (very carefully, it's a userspace list!) |
| 34 | * and mark any locks found there dead, and notify any waiters. |
| 35 | * |
| 36 | * We silently return on any sign of list-walking problem. |
| 37 | */ |
| 38 | void compat_exit_robust_list(struct task_struct *curr) |
| 39 | { |
| 40 | struct compat_robust_list_head __user *head = curr->compat_robust_list; |
| 41 | struct robust_list __user *entry, *pending; |
| 42 | unsigned int limit = ROBUST_LIST_LIMIT, pi, pip; |
| 43 | compat_uptr_t uentry, upending; |
| 44 | compat_long_t futex_offset; |
| 45 | |
| 46 | /* |
| 47 | * Fetch the list head (which was registered earlier, via |
| 48 | * sys_set_robust_list()): |
| 49 | */ |
| 50 | if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi)) |
| 51 | return; |
| 52 | /* |
| 53 | * Fetch the relative futex offset: |
| 54 | */ |
| 55 | if (get_user(futex_offset, &head->futex_offset)) |
| 56 | return; |
| 57 | /* |
| 58 | * Fetch any possibly pending lock-add first, and handle it |
| 59 | * if it exists: |
| 60 | */ |
| 61 | if (fetch_robust_entry(&upending, &pending, |
| 62 | &head->list_op_pending, &pip)) |
| 63 | return; |
| 64 | if (upending) |
| 65 | handle_futex_death((void *)pending + futex_offset, curr, pip); |
| 66 | |
| 67 | while (compat_ptr(uentry) != &head->list) { |
| 68 | /* |
| 69 | * A pending lock might already be on the list, so |
| 70 | * dont process it twice: |
| 71 | */ |
| 72 | if (entry != pending) |
| 73 | if (handle_futex_death((void *)entry + futex_offset, |
| 74 | curr, pi)) |
| 75 | return; |
| 76 | |
| 77 | /* |
| 78 | * Fetch the next entry in the list: |
| 79 | */ |
| 80 | if (fetch_robust_entry(&uentry, &entry, |
| 81 | (compat_uptr_t *)&entry->next, &pi)) |
| 82 | return; |
| 83 | /* |
| 84 | * Avoid excessively long or circular lists: |
| 85 | */ |
| 86 | if (!--limit) |
| 87 | break; |
| 88 | |
| 89 | cond_resched(); |
| 90 | } |
| 91 | } |
| 92 | |
| 93 | asmlinkage long |
| 94 | compat_sys_set_robust_list(struct compat_robust_list_head __user *head, |
| 95 | compat_size_t len) |
| 96 | { |
| 97 | if (unlikely(len != sizeof(*head))) |
| 98 | return -EINVAL; |
| 99 | |
| 100 | current->compat_robust_list = head; |
| 101 | |
| 102 | return 0; |
| 103 | } |
| 104 | |
| 105 | asmlinkage long |
| 106 | compat_sys_get_robust_list(int pid, compat_uptr_t *head_ptr, |
| 107 | compat_size_t __user *len_ptr) |
| 108 | { |
| 109 | struct compat_robust_list_head *head; |
| 110 | unsigned long ret; |
| 111 | |
| 112 | if (!pid) |
| 113 | head = current->compat_robust_list; |
| 114 | else { |
| 115 | struct task_struct *p; |
| 116 | |
| 117 | ret = -ESRCH; |
| 118 | read_lock(&tasklist_lock); |
| 119 | p = find_task_by_pid(pid); |
| 120 | if (!p) |
| 121 | goto err_unlock; |
| 122 | ret = -EPERM; |
| 123 | if ((current->euid != p->euid) && (current->euid != p->uid) && |
| 124 | !capable(CAP_SYS_PTRACE)) |
| 125 | goto err_unlock; |
| 126 | head = p->compat_robust_list; |
| 127 | read_unlock(&tasklist_lock); |
| 128 | } |
| 129 | |
| 130 | if (put_user(sizeof(*head), len_ptr)) |
| 131 | return -EFAULT; |
| 132 | return put_user(ptr_to_compat(head), head_ptr); |
| 133 | |
| 134 | err_unlock: |
| 135 | read_unlock(&tasklist_lock); |
| 136 | |
| 137 | return ret; |
| 138 | } |
| 139 | |
| 140 | asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val, |
| 141 | struct compat_timespec __user *utime, u32 __user *uaddr2, |
| 142 | u32 val3) |
| 143 | { |
| 144 | struct timespec t; |
| 145 | unsigned long timeout = MAX_SCHEDULE_TIMEOUT; |
| 146 | int val2 = 0; |
| 147 | |
| 148 | if (utime && (op == FUTEX_WAIT || op == FUTEX_LOCK_PI)) { |
| 149 | if (get_compat_timespec(&t, utime)) |
| 150 | return -EFAULT; |
| 151 | if (!timespec_valid(&t)) |
| 152 | return -EINVAL; |
| 153 | if (op == FUTEX_WAIT) |
| 154 | timeout = timespec_to_jiffies(&t) + 1; |
| 155 | else { |
| 156 | timeout = t.tv_sec; |
| 157 | val2 = t.tv_nsec; |
| 158 | } |
| 159 | } |
| 160 | if (op == FUTEX_REQUEUE || op == FUTEX_CMP_REQUEUE) |
| 161 | val2 = (int) (unsigned long) utime; |
| 162 | |
| 163 | return do_futex(uaddr, op, val, timeout, uaddr2, val2, val3); |
| 164 | } |