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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 | #include <linux/ptrace.h> |
14 | |
15 | #include <asm/uaccess.h> |
16 | |
17 | |
18 | /* |
19 | * Fetch a robust-list pointer. Bit 0 signals PI futexes: |
20 | */ |
21 | static inline int |
22 | fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry, |
23 | compat_uptr_t __user *head, unsigned int *pi) |
24 | { |
25 | if (get_user(*uentry, head)) |
26 | return -EFAULT; |
27 | |
28 | *entry = compat_ptr((*uentry) & ~1); |
29 | *pi = (unsigned int)(*uentry) & 1; |
30 | |
31 | return 0; |
32 | } |
33 | |
34 | static void __user *futex_uaddr(struct robust_list __user *entry, |
35 | compat_long_t futex_offset) |
36 | { |
37 | compat_uptr_t base = ptr_to_compat(entry); |
38 | void __user *uaddr = compat_ptr(base + futex_offset); |
39 | |
40 | return uaddr; |
41 | } |
42 | |
43 | /* |
44 | * Walk curr->robust_list (very carefully, it's a userspace list!) |
45 | * and mark any locks found there dead, and notify any waiters. |
46 | * |
47 | * We silently return on any sign of list-walking problem. |
48 | */ |
49 | void compat_exit_robust_list(struct task_struct *curr) |
50 | { |
51 | struct compat_robust_list_head __user *head = curr->compat_robust_list; |
52 | struct robust_list __user *entry, *next_entry, *pending; |
53 | unsigned int limit = ROBUST_LIST_LIMIT, pi, pip; |
54 | unsigned int uninitialized_var(next_pi); |
55 | compat_uptr_t uentry, next_uentry, upending; |
56 | compat_long_t futex_offset; |
57 | int rc; |
58 | |
59 | if (!futex_cmpxchg_enabled) |
60 | return; |
61 | |
62 | /* |
63 | * Fetch the list head (which was registered earlier, via |
64 | * sys_set_robust_list()): |
65 | */ |
66 | if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi)) |
67 | return; |
68 | /* |
69 | * Fetch the relative futex offset: |
70 | */ |
71 | if (get_user(futex_offset, &head->futex_offset)) |
72 | return; |
73 | /* |
74 | * Fetch any possibly pending lock-add first, and handle it |
75 | * if it exists: |
76 | */ |
77 | if (fetch_robust_entry(&upending, &pending, |
78 | &head->list_op_pending, &pip)) |
79 | return; |
80 | |
81 | next_entry = NULL; /* avoid warning with gcc */ |
82 | while (entry != (struct robust_list __user *) &head->list) { |
83 | /* |
84 | * Fetch the next entry in the list before calling |
85 | * handle_futex_death: |
86 | */ |
87 | rc = fetch_robust_entry(&next_uentry, &next_entry, |
88 | (compat_uptr_t __user *)&entry->next, &next_pi); |
89 | /* |
90 | * A pending lock might already be on the list, so |
91 | * dont process it twice: |
92 | */ |
93 | if (entry != pending) { |
94 | void __user *uaddr = futex_uaddr(entry, futex_offset); |
95 | |
96 | if (handle_futex_death(uaddr, curr, pi)) |
97 | return; |
98 | } |
99 | if (rc) |
100 | return; |
101 | uentry = next_uentry; |
102 | entry = next_entry; |
103 | pi = next_pi; |
104 | /* |
105 | * Avoid excessively long or circular lists: |
106 | */ |
107 | if (!--limit) |
108 | break; |
109 | |
110 | cond_resched(); |
111 | } |
112 | if (pending) { |
113 | void __user *uaddr = futex_uaddr(pending, futex_offset); |
114 | |
115 | handle_futex_death(uaddr, curr, pip); |
116 | } |
117 | } |
118 | |
119 | asmlinkage long |
120 | compat_sys_set_robust_list(struct compat_robust_list_head __user *head, |
121 | compat_size_t len) |
122 | { |
123 | if (!futex_cmpxchg_enabled) |
124 | return -ENOSYS; |
125 | |
126 | if (unlikely(len != sizeof(*head))) |
127 | return -EINVAL; |
128 | |
129 | current->compat_robust_list = head; |
130 | |
131 | return 0; |
132 | } |
133 | |
134 | asmlinkage long |
135 | compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr, |
136 | compat_size_t __user *len_ptr) |
137 | { |
138 | struct compat_robust_list_head __user *head; |
139 | unsigned long ret; |
140 | struct task_struct *p; |
141 | |
142 | if (!futex_cmpxchg_enabled) |
143 | return -ENOSYS; |
144 | |
145 | WARN_ONCE(1, "deprecated: get_robust_list will be deleted in 2013.\n"); |
146 | |
147 | rcu_read_lock(); |
148 | |
149 | ret = -ESRCH; |
150 | if (!pid) |
151 | p = current; |
152 | else { |
153 | p = find_task_by_vpid(pid); |
154 | if (!p) |
155 | goto err_unlock; |
156 | } |
157 | |
158 | ret = -EPERM; |
159 | if (!ptrace_may_access(p, PTRACE_MODE_READ)) |
160 | goto err_unlock; |
161 | |
162 | head = p->compat_robust_list; |
163 | rcu_read_unlock(); |
164 | |
165 | if (put_user(sizeof(*head), len_ptr)) |
166 | return -EFAULT; |
167 | return put_user(ptr_to_compat(head), head_ptr); |
168 | |
169 | err_unlock: |
170 | rcu_read_unlock(); |
171 | |
172 | return ret; |
173 | } |
174 | |
175 | asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val, |
176 | struct compat_timespec __user *utime, u32 __user *uaddr2, |
177 | u32 val3) |
178 | { |
179 | struct timespec ts; |
180 | ktime_t t, *tp = NULL; |
181 | int val2 = 0; |
182 | int cmd = op & FUTEX_CMD_MASK; |
183 | |
184 | if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
185 | cmd == FUTEX_WAIT_BITSET || |
186 | cmd == FUTEX_WAIT_REQUEUE_PI)) { |
187 | if (get_compat_timespec(&ts, utime)) |
188 | return -EFAULT; |
189 | if (!timespec_valid(&ts)) |
190 | return -EINVAL; |
191 | |
192 | t = timespec_to_ktime(ts); |
193 | if (cmd == FUTEX_WAIT) |
194 | t = ktime_add_safe(ktime_get(), t); |
195 | tp = &t; |
196 | } |
197 | if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
198 | cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) |
199 | val2 = (int) (unsigned long) utime; |
200 | |
201 | return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
202 | } |
203 |
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