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201 lines
4.5 KiB
201 lines
4.5 KiB
/* |
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* linux/kernel/futex_compat.c |
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* |
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* Futex compatibililty routines. |
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* |
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* Copyright 2006, Red Hat, Inc., Ingo Molnar |
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*/ |
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#include <linux/linkage.h> |
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#include <linux/compat.h> |
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#include <linux/nsproxy.h> |
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#include <linux/futex.h> |
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#include <linux/ptrace.h> |
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#include <linux/syscalls.h> |
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#include <asm/uaccess.h> |
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/* |
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* Fetch a robust-list pointer. Bit 0 signals PI futexes: |
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*/ |
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static inline int |
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fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry, |
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compat_uptr_t __user *head, unsigned int *pi) |
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{ |
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if (get_user(*uentry, head)) |
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return -EFAULT; |
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*entry = compat_ptr((*uentry) & ~1); |
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*pi = (unsigned int)(*uentry) & 1; |
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return 0; |
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} |
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static void __user __intentional_overflow(-1) *futex_uaddr(struct robust_list __user *entry, |
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compat_long_t futex_offset) |
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{ |
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compat_uptr_t base = ptr_to_compat(entry); |
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void __user *uaddr = compat_ptr(base + futex_offset); |
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return uaddr; |
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} |
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/* |
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* Walk curr->robust_list (very carefully, it's a userspace list!) |
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* and mark any locks found there dead, and notify any waiters. |
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* |
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* We silently return on any sign of list-walking problem. |
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*/ |
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void compat_exit_robust_list(struct task_struct *curr) |
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{ |
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struct compat_robust_list_head __user *head = curr->compat_robust_list; |
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struct robust_list __user *entry, *next_entry, *pending; |
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unsigned int limit = ROBUST_LIST_LIMIT, pi, pip; |
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unsigned int uninitialized_var(next_pi); |
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compat_uptr_t uentry, next_uentry, upending; |
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compat_long_t futex_offset; |
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int rc; |
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if (!futex_cmpxchg_enabled) |
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return; |
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/* |
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* Fetch the list head (which was registered earlier, via |
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* sys_set_robust_list()): |
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*/ |
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if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi)) |
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return; |
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/* |
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* Fetch the relative futex offset: |
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*/ |
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if (get_user(futex_offset, &head->futex_offset)) |
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return; |
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/* |
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* Fetch any possibly pending lock-add first, and handle it |
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* if it exists: |
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*/ |
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if (fetch_robust_entry(&upending, &pending, |
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&head->list_op_pending, &pip)) |
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return; |
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next_entry = NULL; /* avoid warning with gcc */ |
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while (entry != (struct robust_list __user *) &head->list) { |
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/* |
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* Fetch the next entry in the list before calling |
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* handle_futex_death: |
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*/ |
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rc = fetch_robust_entry(&next_uentry, &next_entry, |
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(compat_uptr_t __user *)&entry->next, &next_pi); |
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/* |
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* A pending lock might already be on the list, so |
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* dont process it twice: |
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*/ |
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if (entry != pending) { |
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void __user *uaddr = futex_uaddr(entry, futex_offset); |
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if (handle_futex_death(uaddr, curr, pi)) |
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return; |
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} |
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if (rc) |
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return; |
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uentry = next_uentry; |
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entry = next_entry; |
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pi = next_pi; |
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/* |
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* Avoid excessively long or circular lists: |
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*/ |
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if (!--limit) |
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break; |
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cond_resched(); |
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} |
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if (pending) { |
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void __user *uaddr = futex_uaddr(pending, futex_offset); |
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handle_futex_death(uaddr, curr, pip); |
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} |
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} |
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COMPAT_SYSCALL_DEFINE2(set_robust_list, |
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struct compat_robust_list_head __user *, head, |
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compat_size_t, len) |
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{ |
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if (!futex_cmpxchg_enabled) |
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return -ENOSYS; |
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if (unlikely(len != sizeof(*head))) |
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return -EINVAL; |
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current->compat_robust_list = head; |
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return 0; |
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} |
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COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid, |
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compat_uptr_t __user *, head_ptr, |
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compat_size_t __user *, len_ptr) |
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{ |
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struct compat_robust_list_head __user *head; |
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unsigned long ret; |
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struct task_struct *p; |
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if (!futex_cmpxchg_enabled) |
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return -ENOSYS; |
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rcu_read_lock(); |
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ret = -ESRCH; |
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if (!pid) |
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p = current; |
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else { |
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p = find_task_by_vpid(pid); |
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if (!p) |
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goto err_unlock; |
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} |
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ret = -EPERM; |
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if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS)) |
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goto err_unlock; |
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head = p->compat_robust_list; |
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rcu_read_unlock(); |
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if (put_user(sizeof(*head), len_ptr)) |
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return -EFAULT; |
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return put_user(ptr_to_compat(head), head_ptr); |
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err_unlock: |
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rcu_read_unlock(); |
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return ret; |
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} |
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COMPAT_SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, |
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struct compat_timespec __user *, utime, u32 __user *, uaddr2, |
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u32, val3) |
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{ |
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struct timespec ts; |
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ktime_t t, *tp = NULL; |
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int val2 = 0; |
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int cmd = op & FUTEX_CMD_MASK; |
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if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
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cmd == FUTEX_WAIT_BITSET || |
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cmd == FUTEX_WAIT_REQUEUE_PI)) { |
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if (compat_get_timespec(&ts, utime)) |
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return -EFAULT; |
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if (!timespec_valid(&ts)) |
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return -EINVAL; |
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t = timespec_to_ktime(ts); |
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if (cmd == FUTEX_WAIT) |
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t = ktime_add_safe(ktime_get(), t); |
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tp = &t; |
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} |
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if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
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cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) |
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val2 = (int) (unsigned long) utime; |
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return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
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}
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