pid namespaces: changes to show virtual ids to user
[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/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 /*
34  * Walk curr->robust_list (very carefully, it's a userspace list!)
35  * and mark any locks found there dead, and notify any waiters.
36  *
37  * We silently return on any sign of list-walking problem.
38  */
39 void compat_exit_robust_list(struct task_struct *curr)
40 {
41         struct compat_robust_list_head __user *head = curr->compat_robust_list;
42         struct robust_list __user *entry, *next_entry, *pending;
43         unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip;
44         compat_uptr_t uentry, next_uentry, upending;
45         compat_long_t futex_offset;
46         int rc;
47
48         /*
49          * Fetch the list head (which was registered earlier, via
50          * sys_set_robust_list()):
51          */
52         if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi))
53                 return;
54         /*
55          * Fetch the relative futex offset:
56          */
57         if (get_user(futex_offset, &head->futex_offset))
58                 return;
59         /*
60          * Fetch any possibly pending lock-add first, and handle it
61          * if it exists:
62          */
63         if (fetch_robust_entry(&upending, &pending,
64                                &head->list_op_pending, &pip))
65                 return;
66
67         next_entry = NULL;      /* avoid warning with gcc */
68         while (entry != (struct robust_list __user *) &head->list) {
69                 /*
70                  * Fetch the next entry in the list before calling
71                  * handle_futex_death:
72                  */
73                 rc = fetch_robust_entry(&next_uentry, &next_entry,
74                         (compat_uptr_t __user *)&entry->next, &next_pi);
75                 /*
76                  * A pending lock might already be on the list, so
77                  * dont process it twice:
78                  */
79                 if (entry != pending)
80                         if (handle_futex_death((void __user *)entry + futex_offset,
81                                                 curr, pi))
82                                 return;
83
84                 if (rc)
85                         return;
86                 uentry = next_uentry;
87                 entry = next_entry;
88                 pi = next_pi;
89                 /*
90                  * Avoid excessively long or circular lists:
91                  */
92                 if (!--limit)
93                         break;
94
95                 cond_resched();
96         }
97         if (pending)
98                 handle_futex_death((void __user *)pending + futex_offset,
99                                    curr, pip);
100 }
101
102 asmlinkage long
103 compat_sys_set_robust_list(struct compat_robust_list_head __user *head,
104                            compat_size_t len)
105 {
106         if (unlikely(len != sizeof(*head)))
107                 return -EINVAL;
108
109         current->compat_robust_list = head;
110
111         return 0;
112 }
113
114 asmlinkage long
115 compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
116                            compat_size_t __user *len_ptr)
117 {
118         struct compat_robust_list_head __user *head;
119         unsigned long ret;
120
121         if (!pid)
122                 head = current->compat_robust_list;
123         else {
124                 struct task_struct *p;
125
126                 ret = -ESRCH;
127                 read_lock(&tasklist_lock);
128                 p = find_task_by_pid_ns(pid,
129                                 current->nsproxy->pid_ns);
130                 if (!p)
131                         goto err_unlock;
132                 ret = -EPERM;
133                 if ((current->euid != p->euid) && (current->euid != p->uid) &&
134                                 !capable(CAP_SYS_PTRACE))
135                         goto err_unlock;
136                 head = p->compat_robust_list;
137                 read_unlock(&tasklist_lock);
138         }
139
140         if (put_user(sizeof(*head), len_ptr))
141                 return -EFAULT;
142         return put_user(ptr_to_compat(head), head_ptr);
143
144 err_unlock:
145         read_unlock(&tasklist_lock);
146
147         return ret;
148 }
149
150 asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val,
151                 struct compat_timespec __user *utime, u32 __user *uaddr2,
152                 u32 val3)
153 {
154         struct timespec ts;
155         ktime_t t, *tp = NULL;
156         int val2 = 0;
157         int cmd = op & FUTEX_CMD_MASK;
158
159         if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI)) {
160                 if (get_compat_timespec(&ts, utime))
161                         return -EFAULT;
162                 if (!timespec_valid(&ts))
163                         return -EINVAL;
164
165                 t = timespec_to_ktime(ts);
166                 if (cmd == FUTEX_WAIT)
167                         t = ktime_add(ktime_get(), t);
168                 tp = &t;
169         }
170         if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE)
171                 val2 = (int) (unsigned long) utime;
172
173         return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
174 }