projects/linux·blob v6.9 · refs

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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 1992 Darren Senn
4 */
5
6/* These are all the functions necessary to implement itimers */
7
8#include <linux/mm.h>
9#include <linux/interrupt.h>
10#include <linux/syscalls.h>
11#include <linux/time.h>
12#include <linux/sched/signal.h>
13#include <linux/sched/cputime.h>
14#include <linux/posix-timers.h>
15#include <linux/hrtimer.h>
16#include <trace/events/timer.h>
17#include <linux/compat.h>
18
19#include <linux/uaccess.h>
20
21/**
22 * itimer_get_remtime - get remaining time for the timer
23 *
24 * @timer: the timer to read
25 *
26 * Returns the delta between the expiry time and now, which can be
27 * less than zero or 1usec for an pending expired timer
28 */
29static struct timespec64 itimer_get_remtime(struct hrtimer *timer)
30{
31 ktime_t rem = __hrtimer_get_remaining(timer, true);
32
33 /*
34 * Racy but safe: if the itimer expires after the above
35 * hrtimer_get_remtime() call but before this condition
36 * then we return 0 - which is correct.
37 */
38 if (hrtimer_active(timer)) {
39 if (rem <= 0)
40 rem = NSEC_PER_USEC;
41 } else
42 rem = 0;
43
44 return ktime_to_timespec64(rem);
45}
46
47static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
48 struct itimerspec64 *const value)
49{
50 u64 val, interval;
51 struct cpu_itimer *it = &tsk->signal->it[clock_id];
52
53 spin_lock_irq(&tsk->sighand->siglock);
54
55 val = it->expires;
56 interval = it->incr;
57 if (val) {
58 u64 t, samples[CPUCLOCK_MAX];
59
60 thread_group_sample_cputime(tsk, samples);
61 t = samples[clock_id];
62
63 if (val < t)
64 /* about to fire */
65 val = TICK_NSEC;
66 else
67 val -= t;
68 }
69
70 spin_unlock_irq(&tsk->sighand->siglock);
71
72 value->it_value = ns_to_timespec64(val);
73 value->it_interval = ns_to_timespec64(interval);
74}
75
76static int do_getitimer(int which, struct itimerspec64 *value)
77{
78 struct task_struct *tsk = current;
79
80 switch (which) {
81 case ITIMER_REAL:
82 spin_lock_irq(&tsk->sighand->siglock);
83 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
84 value->it_interval =
85 ktime_to_timespec64(tsk->signal->it_real_incr);
86 spin_unlock_irq(&tsk->sighand->siglock);
87 break;
88 case ITIMER_VIRTUAL:
89 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
90 break;
91 case ITIMER_PROF:
92 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
93 break;
94 default:
95 return(-EINVAL);
96 }
97 return 0;
98}
99
100static int put_itimerval(struct __kernel_old_itimerval __user *o,
101 const struct itimerspec64 *i)
102{
103 struct __kernel_old_itimerval v;
104
105 v.it_interval.tv_sec = i->it_interval.tv_sec;
106 v.it_interval.tv_usec = i->it_interval.tv_nsec / NSEC_PER_USEC;
107 v.it_value.tv_sec = i->it_value.tv_sec;
108 v.it_value.tv_usec = i->it_value.tv_nsec / NSEC_PER_USEC;
109 return copy_to_user(o, &v, sizeof(struct __kernel_old_itimerval)) ? -EFAULT : 0;
110}
111
112
113SYSCALL_DEFINE2(getitimer, int, which, struct __kernel_old_itimerval __user *, value)
114{
115 struct itimerspec64 get_buffer;
116 int error = do_getitimer(which, &get_buffer);
117
118 if (!error && put_itimerval(value, &get_buffer))
119 error = -EFAULT;
120 return error;
121}
122
123#if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA)
124struct old_itimerval32 {
125 struct old_timeval32 it_interval;
126 struct old_timeval32 it_value;
127};
128
129static int put_old_itimerval32(struct old_itimerval32 __user *o,
130 const struct itimerspec64 *i)
131{
132 struct old_itimerval32 v32;
133
134 v32.it_interval.tv_sec = i->it_interval.tv_sec;
135 v32.it_interval.tv_usec = i->it_interval.tv_nsec / NSEC_PER_USEC;
136 v32.it_value.tv_sec = i->it_value.tv_sec;
137 v32.it_value.tv_usec = i->it_value.tv_nsec / NSEC_PER_USEC;
138 return copy_to_user(o, &v32, sizeof(struct old_itimerval32)) ? -EFAULT : 0;
139}
140
141COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
142 struct old_itimerval32 __user *, value)
143{
144 struct itimerspec64 get_buffer;
145 int error = do_getitimer(which, &get_buffer);
146
147 if (!error && put_old_itimerval32(value, &get_buffer))
148 error = -EFAULT;
149 return error;
150}
151#endif
152
153/*
154 * The timer is automagically restarted, when interval != 0
155 */
156enum hrtimer_restart it_real_fn(struct hrtimer *timer)
157{
158 struct signal_struct *sig =
159 container_of(timer, struct signal_struct, real_timer);
160 struct pid *leader_pid = sig->pids[PIDTYPE_TGID];
161
162 trace_itimer_expire(ITIMER_REAL, leader_pid, 0);
163 kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid);
164
165 return HRTIMER_NORESTART;
166}
167
168static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
169 const struct itimerspec64 *const value,
170 struct itimerspec64 *const ovalue)
171{
172 u64 oval, nval, ointerval, ninterval;
173 struct cpu_itimer *it = &tsk->signal->it[clock_id];
174
175 nval = timespec64_to_ns(&value->it_value);
176 ninterval = timespec64_to_ns(&value->it_interval);
177
178 spin_lock_irq(&tsk->sighand->siglock);
179
180 oval = it->expires;
181 ointerval = it->incr;
182 if (oval || nval) {
183 if (nval > 0)
184 nval += TICK_NSEC;
185 set_process_cpu_timer(tsk, clock_id, &nval, &oval);
186 }
187 it->expires = nval;
188 it->incr = ninterval;
189 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
190 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
191
192 spin_unlock_irq(&tsk->sighand->siglock);
193
194 if (ovalue) {
195 ovalue->it_value = ns_to_timespec64(oval);
196 ovalue->it_interval = ns_to_timespec64(ointerval);
197 }
198}
199
200/*
201 * Returns true if the timeval is in canonical form
202 */
203#define timeval_valid(t) \
204 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
205
206static int do_setitimer(int which, struct itimerspec64 *value,
207 struct itimerspec64 *ovalue)
208{
209 struct task_struct *tsk = current;
210 struct hrtimer *timer;
211 ktime_t expires;
212
213 switch (which) {
214 case ITIMER_REAL:
215again:
216 spin_lock_irq(&tsk->sighand->siglock);
217 timer = &tsk->signal->real_timer;
218 if (ovalue) {
219 ovalue->it_value = itimer_get_remtime(timer);
220 ovalue->it_interval
221 = ktime_to_timespec64(tsk->signal->it_real_incr);
222 }
223 /* We are sharing ->siglock with it_real_fn() */
224 if (hrtimer_try_to_cancel(timer) < 0) {
225 spin_unlock_irq(&tsk->sighand->siglock);
226 hrtimer_cancel_wait_running(timer);
227 goto again;
228 }
229 expires = timespec64_to_ktime(value->it_value);
230 if (expires != 0) {
231 tsk->signal->it_real_incr =
232 timespec64_to_ktime(value->it_interval);
233 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
234 } else
235 tsk->signal->it_real_incr = 0;
236
237 trace_itimer_state(ITIMER_REAL, value, 0);
238 spin_unlock_irq(&tsk->sighand->siglock);
239 break;
240 case ITIMER_VIRTUAL:
241 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
242 break;
243 case ITIMER_PROF:
244 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
245 break;
246 default:
247 return -EINVAL;
248 }
249 return 0;
250}
251
252#ifdef CONFIG_SECURITY_SELINUX
253void clear_itimer(void)
254{
255 struct itimerspec64 v = {};
256 int i;
257
258 for (i = 0; i < 3; i++)
259 do_setitimer(i, &v, NULL);
260}
261#endif
262
263#ifdef __ARCH_WANT_SYS_ALARM
264
265/**
266 * alarm_setitimer - set alarm in seconds
267 *
268 * @seconds: number of seconds until alarm
269 * 0 disables the alarm
270 *
271 * Returns the remaining time in seconds of a pending timer or 0 when
272 * the timer is not active.
273 *
274 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
275 * negative timeval settings which would cause immediate expiry.
276 */
277static unsigned int alarm_setitimer(unsigned int seconds)
278{
279 struct itimerspec64 it_new, it_old;
280
281#if BITS_PER_LONG < 64
282 if (seconds > INT_MAX)
283 seconds = INT_MAX;
284#endif
285 it_new.it_value.tv_sec = seconds;
286 it_new.it_value.tv_nsec = 0;
287 it_new.it_interval.tv_sec = it_new.it_interval.tv_nsec = 0;
288
289 do_setitimer(ITIMER_REAL, &it_new, &it_old);
290
291 /*
292 * We can't return 0 if we have an alarm pending ... And we'd
293 * better return too much than too little anyway
294 */
295 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_nsec) ||
296 it_old.it_value.tv_nsec >= (NSEC_PER_SEC / 2))
297 it_old.it_value.tv_sec++;
298
299 return it_old.it_value.tv_sec;
300}
301
302/*
303 * For backwards compatibility? This can be done in libc so Alpha
304 * and all newer ports shouldn't need it.
305 */
306SYSCALL_DEFINE1(alarm, unsigned int, seconds)
307{
308 return alarm_setitimer(seconds);
309}
310
311#endif
312
313static int get_itimerval(struct itimerspec64 *o, const struct __kernel_old_itimerval __user *i)
314{
315 struct __kernel_old_itimerval v;
316
317 if (copy_from_user(&v, i, sizeof(struct __kernel_old_itimerval)))
318 return -EFAULT;
319
320 /* Validate the timevals in value. */
321 if (!timeval_valid(&v.it_value) ||
322 !timeval_valid(&v.it_interval))
323 return -EINVAL;
324
325 o->it_interval.tv_sec = v.it_interval.tv_sec;
326 o->it_interval.tv_nsec = v.it_interval.tv_usec * NSEC_PER_USEC;
327 o->it_value.tv_sec = v.it_value.tv_sec;
328 o->it_value.tv_nsec = v.it_value.tv_usec * NSEC_PER_USEC;
329 return 0;
330}
331
332SYSCALL_DEFINE3(setitimer, int, which, struct __kernel_old_itimerval __user *, value,
333 struct __kernel_old_itimerval __user *, ovalue)
334{
335 struct itimerspec64 set_buffer, get_buffer;
336 int error;
337
338 if (value) {
339 error = get_itimerval(&set_buffer, value);
340 if (error)
341 return error;
342 } else {
343 memset(&set_buffer, 0, sizeof(set_buffer));
344 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
345 " Misfeature support will be removed\n",
346 current->comm);
347 }
348
349 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
350 if (error || !ovalue)
351 return error;
352
353 if (put_itimerval(ovalue, &get_buffer))
354 return -EFAULT;
355 return 0;
356}
357
358#if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA)
359static int get_old_itimerval32(struct itimerspec64 *o, const struct old_itimerval32 __user *i)
360{
361 struct old_itimerval32 v32;
362
363 if (copy_from_user(&v32, i, sizeof(struct old_itimerval32)))
364 return -EFAULT;
365
366 /* Validate the timevals in value. */
367 if (!timeval_valid(&v32.it_value) ||
368 !timeval_valid(&v32.it_interval))
369 return -EINVAL;
370
371 o->it_interval.tv_sec = v32.it_interval.tv_sec;
372 o->it_interval.tv_nsec = v32.it_interval.tv_usec * NSEC_PER_USEC;
373 o->it_value.tv_sec = v32.it_value.tv_sec;
374 o->it_value.tv_nsec = v32.it_value.tv_usec * NSEC_PER_USEC;
375 return 0;
376}
377
378COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
379 struct old_itimerval32 __user *, value,
380 struct old_itimerval32 __user *, ovalue)
381{
382 struct itimerspec64 set_buffer, get_buffer;
383 int error;
384
385 if (value) {
386 error = get_old_itimerval32(&set_buffer, value);
387 if (error)
388 return error;
389 } else {
390 memset(&set_buffer, 0, sizeof(set_buffer));
391 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
392 " Misfeature support will be removed\n",
393 current->comm);
394 }
395
396 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
397 if (error || !ovalue)
398 return error;
399 if (put_old_itimerval32(ovalue, &get_buffer))
400 return -EFAULT;
401 return 0;
402}
403#endif