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