fix compat futex code for private futexes
[linux-2.6.git] / kernel / futex_compat.c
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 __user *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 __user *)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 __user *)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 __user *)&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 __user *head_ptr,
107                            compat_size_t __user *len_ptr)
108 {
109         struct compat_robust_list_head __user *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 ts;
145         ktime_t t, *tp = NULL;
146         int val2 = 0;
147         int cmd = op & FUTEX_CMD_MASK;
148
149         if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI)) {
150                 if (get_compat_timespec(&ts, utime))
151                         return -EFAULT;
152                 if (!timespec_valid(&ts))
153                         return -EINVAL;
154
155                 t = timespec_to_ktime(ts);
156                 if (cmd == FUTEX_WAIT)
157                         t = ktime_add(ktime_get(), t);
158                 tp = &t;
159         }
160         if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE
161             || cmd == FUTEX_CMP_REQUEUE_PI)
162                 val2 = (int) (unsigned long) utime;
163
164         return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
165 }