| 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/nsproxy.h> |
| 12 | #include <linux/futex.h> |
| 13 | |
| 14 | #include <asm/uaccess.h> |
| 15 | |
| 16 | |
| 17 | /* |
| 18 | * Fetch a robust-list pointer. Bit 0 signals PI futexes: |
| 19 | */ |
| 20 | static inline int |
| 21 | fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry, |
| 22 | compat_uptr_t __user *head, int *pi) |
| 23 | { |
| 24 | if (get_user(*uentry, head)) |
| 25 | return -EFAULT; |
| 26 | |
| 27 | *entry = compat_ptr((*uentry) & ~1); |
| 28 | *pi = (unsigned int)(*uentry) & 1; |
| 29 | |
| 30 | return 0; |
| 31 | } |
| 32 | |
| 33 | static void __user *futex_uaddr(struct robust_list __user *entry, |
| 34 | compat_long_t futex_offset) |
| 35 | { |
| 36 | compat_uptr_t base = ptr_to_compat(entry); |
| 37 | void __user *uaddr = compat_ptr(base + futex_offset); |
| 38 | |
| 39 | return uaddr; |
| 40 | } |
| 41 | |
| 42 | /* |
| 43 | * Walk curr->robust_list (very carefully, it's a userspace list!) |
| 44 | * and mark any locks found there dead, and notify any waiters. |
| 45 | * |
| 46 | * We silently return on any sign of list-walking problem. |
| 47 | */ |
| 48 | void compat_exit_robust_list(struct task_struct *curr) |
| 49 | { |
| 50 | struct compat_robust_list_head __user *head = curr->compat_robust_list; |
| 51 | struct robust_list __user *entry, *next_entry, *pending; |
| 52 | unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip; |
| 53 | compat_uptr_t uentry, next_uentry, upending; |
| 54 | compat_long_t futex_offset; |
| 55 | int rc; |
| 56 | |
| 57 | if (!futex_cmpxchg_enabled) |
| 58 | return; |
| 59 | |
| 60 | /* |
| 61 | * Fetch the list head (which was registered earlier, via |
| 62 | * sys_set_robust_list()): |
| 63 | */ |
| 64 | if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi)) |
| 65 | return; |
| 66 | /* |
| 67 | * Fetch the relative futex offset: |
| 68 | */ |
| 69 | if (get_user(futex_offset, &head->futex_offset)) |
| 70 | return; |
| 71 | /* |
| 72 | * Fetch any possibly pending lock-add first, and handle it |
| 73 | * if it exists: |
| 74 | */ |
| 75 | if (fetch_robust_entry(&upending, &pending, |
| 76 | &head->list_op_pending, &pip)) |
| 77 | return; |
| 78 | |
| 79 | next_entry = NULL; /* avoid warning with gcc */ |
| 80 | while (entry != (struct robust_list __user *) &head->list) { |
| 81 | /* |
| 82 | * Fetch the next entry in the list before calling |
| 83 | * handle_futex_death: |
| 84 | */ |
| 85 | rc = fetch_robust_entry(&next_uentry, &next_entry, |
| 86 | (compat_uptr_t __user *)&entry->next, &next_pi); |
| 87 | /* |
| 88 | * A pending lock might already be on the list, so |
| 89 | * dont process it twice: |
| 90 | */ |
| 91 | if (entry != pending) { |
| 92 | void __user *uaddr = futex_uaddr(entry, futex_offset); |
| 93 | |
| 94 | if (handle_futex_death(uaddr, curr, pi)) |
| 95 | return; |
| 96 | } |
| 97 | if (rc) |
| 98 | return; |
| 99 | uentry = next_uentry; |
| 100 | entry = next_entry; |
| 101 | pi = next_pi; |
| 102 | /* |
| 103 | * Avoid excessively long or circular lists: |
| 104 | */ |
| 105 | if (!--limit) |
| 106 | break; |
| 107 | |
| 108 | cond_resched(); |
| 109 | } |
| 110 | if (pending) { |
| 111 | void __user *uaddr = futex_uaddr(pending, futex_offset); |
| 112 | |
| 113 | handle_futex_death(uaddr, curr, pip); |
| 114 | } |
| 115 | } |
| 116 | |
| 117 | asmlinkage long |
| 118 | compat_sys_set_robust_list(struct compat_robust_list_head __user *head, |
| 119 | compat_size_t len) |
| 120 | { |
| 121 | if (!futex_cmpxchg_enabled) |
| 122 | return -ENOSYS; |
| 123 | |
| 124 | if (unlikely(len != sizeof(*head))) |
| 125 | return -EINVAL; |
| 126 | |
| 127 | current->compat_robust_list = head; |
| 128 | |
| 129 | return 0; |
| 130 | } |
| 131 | |
| 132 | asmlinkage long |
| 133 | compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr, |
| 134 | compat_size_t __user *len_ptr) |
| 135 | { |
| 136 | struct compat_robust_list_head __user *head; |
| 137 | unsigned long ret; |
| 138 | const struct cred *cred = current_cred(), *pcred; |
| 139 | |
| 140 | if (!futex_cmpxchg_enabled) |
| 141 | return -ENOSYS; |
| 142 | |
| 143 | if (!pid) |
| 144 | head = current->compat_robust_list; |
| 145 | else { |
| 146 | struct task_struct *p; |
| 147 | |
| 148 | ret = -ESRCH; |
| 149 | rcu_read_lock(); |
| 150 | p = find_task_by_vpid(pid); |
| 151 | if (!p) |
| 152 | goto err_unlock; |
| 153 | ret = -EPERM; |
| 154 | pcred = __task_cred(p); |
| 155 | if (cred->euid != pcred->euid && |
| 156 | cred->euid != pcred->uid && |
| 157 | !capable(CAP_SYS_PTRACE)) |
| 158 | goto err_unlock; |
| 159 | head = p->compat_robust_list; |
| 160 | rcu_read_unlock(); |
| 161 | } |
| 162 | |
| 163 | if (put_user(sizeof(*head), len_ptr)) |
| 164 | return -EFAULT; |
| 165 | return put_user(ptr_to_compat(head), head_ptr); |
| 166 | |
| 167 | err_unlock: |
| 168 | rcu_read_unlock(); |
| 169 | |
| 170 | return ret; |
| 171 | } |
| 172 | |
| 173 | asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val, |
| 174 | struct compat_timespec __user *utime, u32 __user *uaddr2, |
| 175 | u32 val3) |
| 176 | { |
| 177 | struct timespec ts; |
| 178 | ktime_t t, *tp = NULL; |
| 179 | int val2 = 0; |
| 180 | int cmd = op & FUTEX_CMD_MASK; |
| 181 | |
| 182 | if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
| 183 | cmd == FUTEX_WAIT_BITSET || |
| 184 | cmd == FUTEX_WAIT_REQUEUE_PI)) { |
| 185 | if (get_compat_timespec(&ts, utime)) |
| 186 | return -EFAULT; |
| 187 | if (!timespec_valid(&ts)) |
| 188 | return -EINVAL; |
| 189 | |
| 190 | t = timespec_to_ktime(ts); |
| 191 | if (cmd == FUTEX_WAIT) |
| 192 | t = ktime_add_safe(ktime_get(), t); |
| 193 | tp = &t; |
| 194 | } |
| 195 | if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
| 196 | cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) |
| 197 | val2 = (int) (unsigned long) utime; |
| 198 | |
| 199 | return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
| 200 | } |