blob: 4ae3232e7a28a507d5ba316d9603c4275012a7ad
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 | #include <linux/syscalls.h> |
15 | |
16 | #include <asm/uaccess.h> |
17 | |
18 | |
19 | /* |
20 | * Fetch a robust-list pointer. Bit 0 signals PI futexes: |
21 | */ |
22 | static inline int |
23 | fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry, |
24 | compat_uptr_t __user *head, unsigned int *pi) |
25 | { |
26 | if (get_user(*uentry, head)) |
27 | return -EFAULT; |
28 | |
29 | *entry = compat_ptr((*uentry) & ~1); |
30 | *pi = (unsigned int)(*uentry) & 1; |
31 | |
32 | return 0; |
33 | } |
34 | |
35 | static void __user *futex_uaddr(struct robust_list __user *entry, |
36 | compat_long_t futex_offset) |
37 | { |
38 | compat_uptr_t base = ptr_to_compat(entry); |
39 | void __user *uaddr = compat_ptr(base + futex_offset); |
40 | |
41 | return uaddr; |
42 | } |
43 | |
44 | /* |
45 | * Walk curr->robust_list (very carefully, it's a userspace list!) |
46 | * and mark any locks found there dead, and notify any waiters. |
47 | * |
48 | * We silently return on any sign of list-walking problem. |
49 | */ |
50 | void compat_exit_robust_list(struct task_struct *curr) |
51 | { |
52 | struct compat_robust_list_head __user *head = curr->compat_robust_list; |
53 | struct robust_list __user *entry, *next_entry, *pending; |
54 | unsigned int limit = ROBUST_LIST_LIMIT, pi, pip; |
55 | unsigned int uninitialized_var(next_pi); |
56 | compat_uptr_t uentry, next_uentry, upending; |
57 | compat_long_t futex_offset; |
58 | int rc; |
59 | |
60 | if (!futex_cmpxchg_enabled) |
61 | return; |
62 | |
63 | /* |
64 | * Fetch the list head (which was registered earlier, via |
65 | * sys_set_robust_list()): |
66 | */ |
67 | if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi)) |
68 | return; |
69 | /* |
70 | * Fetch the relative futex offset: |
71 | */ |
72 | if (get_user(futex_offset, &head->futex_offset)) |
73 | return; |
74 | /* |
75 | * Fetch any possibly pending lock-add first, and handle it |
76 | * if it exists: |
77 | */ |
78 | if (fetch_robust_entry(&upending, &pending, |
79 | &head->list_op_pending, &pip)) |
80 | return; |
81 | |
82 | next_entry = NULL; /* avoid warning with gcc */ |
83 | while (entry != (struct robust_list __user *) &head->list) { |
84 | /* |
85 | * Fetch the next entry in the list before calling |
86 | * handle_futex_death: |
87 | */ |
88 | rc = fetch_robust_entry(&next_uentry, &next_entry, |
89 | (compat_uptr_t __user *)&entry->next, &next_pi); |
90 | /* |
91 | * A pending lock might already be on the list, so |
92 | * dont process it twice: |
93 | */ |
94 | if (entry != pending) { |
95 | void __user *uaddr = futex_uaddr(entry, futex_offset); |
96 | |
97 | if (handle_futex_death(uaddr, curr, pi)) |
98 | return; |
99 | } |
100 | if (rc) |
101 | return; |
102 | uentry = next_uentry; |
103 | entry = next_entry; |
104 | pi = next_pi; |
105 | /* |
106 | * Avoid excessively long or circular lists: |
107 | */ |
108 | if (!--limit) |
109 | break; |
110 | |
111 | cond_resched(); |
112 | } |
113 | if (pending) { |
114 | void __user *uaddr = futex_uaddr(pending, futex_offset); |
115 | |
116 | handle_futex_death(uaddr, curr, pip); |
117 | } |
118 | } |
119 | |
120 | COMPAT_SYSCALL_DEFINE2(set_robust_list, |
121 | struct compat_robust_list_head __user *, head, |
122 | compat_size_t, len) |
123 | { |
124 | if (!futex_cmpxchg_enabled) |
125 | return -ENOSYS; |
126 | |
127 | if (unlikely(len != sizeof(*head))) |
128 | return -EINVAL; |
129 | |
130 | current->compat_robust_list = head; |
131 | |
132 | return 0; |
133 | } |
134 | |
135 | COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid, |
136 | compat_uptr_t __user *, head_ptr, |
137 | compat_size_t __user *, len_ptr) |
138 | { |
139 | struct compat_robust_list_head __user *head; |
140 | unsigned long ret; |
141 | struct task_struct *p; |
142 | |
143 | if (!futex_cmpxchg_enabled) |
144 | return -ENOSYS; |
145 | |
146 | rcu_read_lock(); |
147 | |
148 | ret = -ESRCH; |
149 | if (!pid) |
150 | p = current; |
151 | else { |
152 | p = find_task_by_vpid(pid); |
153 | if (!p) |
154 | goto err_unlock; |
155 | } |
156 | |
157 | ret = -EPERM; |
158 | if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS)) |
159 | goto err_unlock; |
160 | |
161 | head = p->compat_robust_list; |
162 | rcu_read_unlock(); |
163 | |
164 | if (put_user(sizeof(*head), len_ptr)) |
165 | return -EFAULT; |
166 | return put_user(ptr_to_compat(head), head_ptr); |
167 | |
168 | err_unlock: |
169 | rcu_read_unlock(); |
170 | |
171 | return ret; |
172 | } |
173 | |
174 | COMPAT_SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, |
175 | struct compat_timespec __user *, utime, u32 __user *, uaddr2, |
176 | u32, val3) |
177 | { |
178 | struct timespec ts; |
179 | ktime_t t, *tp = NULL; |
180 | int val2 = 0; |
181 | int cmd = op & FUTEX_CMD_MASK; |
182 | |
183 | if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
184 | cmd == FUTEX_WAIT_BITSET || |
185 | cmd == FUTEX_WAIT_REQUEUE_PI)) { |
186 | if (compat_get_timespec(&ts, utime)) |
187 | return -EFAULT; |
188 | if (!timespec_valid(&ts)) |
189 | return -EINVAL; |
190 | |
191 | t = timespec_to_ktime(ts); |
192 | if (cmd == FUTEX_WAIT) |
193 | t = ktime_add_safe(ktime_get(), t); |
194 | tp = &t; |
195 | } |
196 | if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
197 | cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) |
198 | val2 = (int) (unsigned long) utime; |
199 | |
200 | return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
201 | } |
202 |