Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
34f192c6 IM |
2 | /* |
3 | * linux/kernel/futex_compat.c | |
4 | * | |
5 | * Futex compatibililty routines. | |
6 | * | |
7 | * Copyright 2006, Red Hat, Inc., Ingo Molnar | |
8 | */ | |
9 | ||
10 | #include <linux/linkage.h> | |
11 | #include <linux/compat.h> | |
b488893a | 12 | #include <linux/nsproxy.h> |
34f192c6 | 13 | #include <linux/futex.h> |
bdbb776f | 14 | #include <linux/ptrace.h> |
90caf58d | 15 | #include <linux/syscalls.h> |
34f192c6 | 16 | |
7c0f6ba6 | 17 | #include <linux/uaccess.h> |
34f192c6 | 18 | |
e3f2ddea IM |
19 | |
20 | /* | |
21 | * Fetch a robust-list pointer. Bit 0 signals PI futexes: | |
22 | */ | |
23 | static inline int | |
24 | fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry, | |
1dcc41bb | 25 | compat_uptr_t __user *head, unsigned int *pi) |
e3f2ddea IM |
26 | { |
27 | if (get_user(*uentry, head)) | |
28 | return -EFAULT; | |
29 | ||
30 | *entry = compat_ptr((*uentry) & ~1); | |
31 | *pi = (unsigned int)(*uentry) & 1; | |
32 | ||
33 | return 0; | |
34 | } | |
35 | ||
8481664d | 36 | static void __user *futex_uaddr(struct robust_list __user *entry, |
3c5fd9c7 DM |
37 | compat_long_t futex_offset) |
38 | { | |
39 | compat_uptr_t base = ptr_to_compat(entry); | |
40 | void __user *uaddr = compat_ptr(base + futex_offset); | |
41 | ||
42 | return uaddr; | |
43 | } | |
44 | ||
34f192c6 IM |
45 | /* |
46 | * Walk curr->robust_list (very carefully, it's a userspace list!) | |
47 | * and mark any locks found there dead, and notify any waiters. | |
48 | * | |
49 | * We silently return on any sign of list-walking problem. | |
50 | */ | |
51 | void compat_exit_robust_list(struct task_struct *curr) | |
52 | { | |
53 | struct compat_robust_list_head __user *head = curr->compat_robust_list; | |
9f96cb1e | 54 | struct robust_list __user *entry, *next_entry, *pending; |
4c115e95 DH |
55 | unsigned int limit = ROBUST_LIST_LIMIT, pi, pip; |
56 | unsigned int uninitialized_var(next_pi); | |
9f96cb1e | 57 | compat_uptr_t uentry, next_uentry, upending; |
34f192c6 | 58 | compat_long_t futex_offset; |
9f96cb1e | 59 | int rc; |
34f192c6 | 60 | |
a0c1e907 TG |
61 | if (!futex_cmpxchg_enabled) |
62 | return; | |
63 | ||
34f192c6 IM |
64 | /* |
65 | * Fetch the list head (which was registered earlier, via | |
66 | * sys_set_robust_list()): | |
67 | */ | |
e3f2ddea | 68 | if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi)) |
34f192c6 | 69 | return; |
34f192c6 IM |
70 | /* |
71 | * Fetch the relative futex offset: | |
72 | */ | |
73 | if (get_user(futex_offset, &head->futex_offset)) | |
74 | return; | |
75 | /* | |
76 | * Fetch any possibly pending lock-add first, and handle it | |
77 | * if it exists: | |
78 | */ | |
e3f2ddea | 79 | if (fetch_robust_entry(&upending, &pending, |
ce2c6b53 | 80 | &head->list_op_pending, &pip)) |
34f192c6 | 81 | return; |
34f192c6 | 82 | |
9f96cb1e | 83 | next_entry = NULL; /* avoid warning with gcc */ |
179c85ea | 84 | while (entry != (struct robust_list __user *) &head->list) { |
9f96cb1e MS |
85 | /* |
86 | * Fetch the next entry in the list before calling | |
87 | * handle_futex_death: | |
88 | */ | |
89 | rc = fetch_robust_entry(&next_uentry, &next_entry, | |
90 | (compat_uptr_t __user *)&entry->next, &next_pi); | |
34f192c6 IM |
91 | /* |
92 | * A pending lock might already be on the list, so | |
93 | * dont process it twice: | |
94 | */ | |
3c5fd9c7 DM |
95 | if (entry != pending) { |
96 | void __user *uaddr = futex_uaddr(entry, futex_offset); | |
34f192c6 | 97 | |
3c5fd9c7 DM |
98 | if (handle_futex_death(uaddr, curr, pi)) |
99 | return; | |
100 | } | |
9f96cb1e | 101 | if (rc) |
34f192c6 | 102 | return; |
9f96cb1e MS |
103 | uentry = next_uentry; |
104 | entry = next_entry; | |
105 | pi = next_pi; | |
34f192c6 IM |
106 | /* |
107 | * Avoid excessively long or circular lists: | |
108 | */ | |
109 | if (!--limit) | |
110 | break; | |
111 | ||
112 | cond_resched(); | |
113 | } | |
3c5fd9c7 DM |
114 | if (pending) { |
115 | void __user *uaddr = futex_uaddr(pending, futex_offset); | |
116 | ||
117 | handle_futex_death(uaddr, curr, pip); | |
118 | } | |
34f192c6 IM |
119 | } |
120 | ||
90caf58d AV |
121 | COMPAT_SYSCALL_DEFINE2(set_robust_list, |
122 | struct compat_robust_list_head __user *, head, | |
123 | compat_size_t, len) | |
34f192c6 | 124 | { |
a0c1e907 TG |
125 | if (!futex_cmpxchg_enabled) |
126 | return -ENOSYS; | |
127 | ||
34f192c6 IM |
128 | if (unlikely(len != sizeof(*head))) |
129 | return -EINVAL; | |
130 | ||
131 | current->compat_robust_list = head; | |
132 | ||
133 | return 0; | |
134 | } | |
135 | ||
90caf58d AV |
136 | COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid, |
137 | compat_uptr_t __user *, head_ptr, | |
138 | compat_size_t __user *, len_ptr) | |
34f192c6 | 139 | { |
ba46df98 | 140 | struct compat_robust_list_head __user *head; |
34f192c6 | 141 | unsigned long ret; |
bdbb776f | 142 | struct task_struct *p; |
34f192c6 | 143 | |
a0c1e907 TG |
144 | if (!futex_cmpxchg_enabled) |
145 | return -ENOSYS; | |
146 | ||
bdbb776f KC |
147 | rcu_read_lock(); |
148 | ||
149 | ret = -ESRCH; | |
34f192c6 | 150 | if (!pid) |
bdbb776f | 151 | p = current; |
34f192c6 | 152 | else { |
228ebcbe | 153 | p = find_task_by_vpid(pid); |
34f192c6 IM |
154 | if (!p) |
155 | goto err_unlock; | |
34f192c6 IM |
156 | } |
157 | ||
bdbb776f | 158 | ret = -EPERM; |
caaee623 | 159 | if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS)) |
bdbb776f KC |
160 | goto err_unlock; |
161 | ||
162 | head = p->compat_robust_list; | |
163 | rcu_read_unlock(); | |
164 | ||
34f192c6 IM |
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: | |
f409adf5 | 170 | rcu_read_unlock(); |
34f192c6 IM |
171 | |
172 | return ret; | |
173 | } | |
174 | ||
90caf58d | 175 | COMPAT_SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, |
9afc5eee | 176 | struct old_timespec32 __user *, utime, u32 __user *, uaddr2, |
90caf58d | 177 | u32, val3) |
34f192c6 | 178 | { |
c19384b5 PP |
179 | struct timespec ts; |
180 | ktime_t t, *tp = NULL; | |
34f192c6 | 181 | int val2 = 0; |
f0ede66f | 182 | int cmd = op & FUTEX_CMD_MASK; |
34f192c6 | 183 | |
cd689985 | 184 | if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
4dc88029 DG |
185 | cmd == FUTEX_WAIT_BITSET || |
186 | cmd == FUTEX_WAIT_REQUEUE_PI)) { | |
81993e81 | 187 | if (compat_get_timespec(&ts, utime)) |
34f192c6 | 188 | return -EFAULT; |
c19384b5 | 189 | if (!timespec_valid(&ts)) |
9741ef96 | 190 | return -EINVAL; |
c19384b5 PP |
191 | |
192 | t = timespec_to_ktime(ts); | |
f0ede66f | 193 | if (cmd == FUTEX_WAIT) |
5a7780e7 | 194 | t = ktime_add_safe(ktime_get(), t); |
c19384b5 | 195 | tp = &t; |
34f192c6 | 196 | } |
4dc88029 DG |
197 | if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
198 | cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) | |
34f192c6 IM |
199 | val2 = (int) (unsigned long) utime; |
200 | ||
c19384b5 | 201 | return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
34f192c6 | 202 | } |