Line data Source code
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 : */
29 206 : static struct timespec64 itimer_get_remtime(struct hrtimer *timer)
30 : {
31 206 : 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 : */
38 206 : if (hrtimer_active(timer)) {
39 88 : if (rem <= 0)
40 0 : rem = NSEC_PER_USEC;
41 : } else
42 : rem = 0;
43 :
44 206 : return ktime_to_timespec64(rem);
45 : }
46 :
47 0 : static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
48 : struct itimerspec64 *const value)
49 : {
50 0 : u64 val, interval;
51 0 : struct cpu_itimer *it = &tsk->signal->it[clock_id];
52 :
53 0 : spin_lock_irq(&tsk->sighand->siglock);
54 :
55 0 : val = it->expires;
56 0 : interval = it->incr;
57 0 : if (val) {
58 0 : u64 t, samples[CPUCLOCK_MAX];
59 :
60 0 : thread_group_sample_cputime(tsk, samples);
61 0 : t = samples[clock_id];
62 :
63 0 : if (val < t)
64 : /* about to fire */
65 : val = TICK_NSEC;
66 : else
67 0 : val -= t;
68 : }
69 :
70 0 : spin_unlock_irq(&tsk->sighand->siglock);
71 :
72 0 : value->it_value = ns_to_timespec64(val);
73 0 : value->it_interval = ns_to_timespec64(interval);
74 0 : }
75 :
76 0 : static int do_getitimer(int which, struct itimerspec64 *value)
77 : {
78 0 : struct task_struct *tsk = current;
79 :
80 0 : switch (which) {
81 0 : case ITIMER_REAL:
82 0 : spin_lock_irq(&tsk->sighand->siglock);
83 0 : value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
84 0 : value->it_interval =
85 0 : ktime_to_timespec64(tsk->signal->it_real_incr);
86 0 : spin_unlock_irq(&tsk->sighand->siglock);
87 : break;
88 0 : case ITIMER_VIRTUAL:
89 0 : get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
90 0 : break;
91 0 : case ITIMER_PROF:
92 0 : get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
93 0 : break;
94 : default:
95 : return(-EINVAL);
96 : }
97 : return 0;
98 : }
99 :
100 0 : static int put_itimerval(struct __kernel_old_itimerval __user *o,
101 : const struct itimerspec64 *i)
102 : {
103 0 : struct __kernel_old_itimerval v;
104 :
105 0 : v.it_interval.tv_sec = i->it_interval.tv_sec;
106 0 : v.it_interval.tv_usec = i->it_interval.tv_nsec / NSEC_PER_USEC;
107 0 : v.it_value.tv_sec = i->it_value.tv_sec;
108 0 : v.it_value.tv_usec = i->it_value.tv_nsec / NSEC_PER_USEC;
109 0 : return copy_to_user(o, &v, sizeof(struct __kernel_old_itimerval)) ? -EFAULT : 0;
110 : }
111 :
112 :
113 0 : SYSCALL_DEFINE2(getitimer, int, which, struct __kernel_old_itimerval __user *, value)
114 : {
115 0 : struct itimerspec64 get_buffer;
116 0 : int error = do_getitimer(which, &get_buffer);
117 :
118 0 : if (!error && put_itimerval(value, &get_buffer))
119 0 : error = -EFAULT;
120 0 : return error;
121 : }
122 :
123 : #if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA)
124 : struct old_itimerval32 {
125 : struct old_timeval32 it_interval;
126 : struct old_timeval32 it_value;
127 : };
128 :
129 0 : static int put_old_itimerval32(struct old_itimerval32 __user *o,
130 : const struct itimerspec64 *i)
131 : {
132 0 : struct old_itimerval32 v32;
133 :
134 0 : v32.it_interval.tv_sec = i->it_interval.tv_sec;
135 0 : v32.it_interval.tv_usec = i->it_interval.tv_nsec / NSEC_PER_USEC;
136 0 : v32.it_value.tv_sec = i->it_value.tv_sec;
137 0 : v32.it_value.tv_usec = i->it_value.tv_nsec / NSEC_PER_USEC;
138 0 : return copy_to_user(o, &v32, sizeof(struct old_itimerval32)) ? -EFAULT : 0;
139 : }
140 :
141 0 : COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
142 : struct old_itimerval32 __user *, value)
143 : {
144 0 : struct itimerspec64 get_buffer;
145 0 : int error = do_getitimer(which, &get_buffer);
146 :
147 0 : if (!error && put_old_itimerval32(value, &get_buffer))
148 0 : error = -EFAULT;
149 0 : return error;
150 : }
151 : #endif
152 :
153 : /*
154 : * The timer is automagically restarted, when interval != 0
155 : */
156 0 : enum hrtimer_restart it_real_fn(struct hrtimer *timer)
157 : {
158 0 : struct signal_struct *sig =
159 0 : container_of(timer, struct signal_struct, real_timer);
160 0 : struct pid *leader_pid = sig->pids[PIDTYPE_TGID];
161 :
162 0 : trace_itimer_expire(ITIMER_REAL, leader_pid, 0);
163 0 : kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid);
164 :
165 0 : return HRTIMER_NORESTART;
166 : }
167 :
168 0 : static 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 0 : u64 oval, nval, ointerval, ninterval;
173 0 : struct cpu_itimer *it = &tsk->signal->it[clock_id];
174 :
175 0 : nval = timespec64_to_ns(&value->it_value);
176 0 : ninterval = timespec64_to_ns(&value->it_interval);
177 :
178 0 : spin_lock_irq(&tsk->sighand->siglock);
179 :
180 0 : oval = it->expires;
181 0 : ointerval = it->incr;
182 0 : if (oval || nval) {
183 0 : if (nval > 0)
184 0 : nval += TICK_NSEC;
185 0 : set_process_cpu_timer(tsk, clock_id, &nval, &oval);
186 : }
187 0 : it->expires = nval;
188 0 : it->incr = ninterval;
189 0 : trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
190 : ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
191 :
192 0 : spin_unlock_irq(&tsk->sighand->siglock);
193 :
194 0 : if (ovalue) {
195 0 : ovalue->it_value = ns_to_timespec64(oval);
196 0 : ovalue->it_interval = ns_to_timespec64(ointerval);
197 : }
198 0 : }
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 :
206 206 : static int do_setitimer(int which, struct itimerspec64 *value,
207 : struct itimerspec64 *ovalue)
208 : {
209 206 : struct task_struct *tsk = current;
210 206 : struct hrtimer *timer;
211 206 : ktime_t expires;
212 :
213 206 : switch (which) {
214 : case ITIMER_REAL:
215 206 : again:
216 206 : spin_lock_irq(&tsk->sighand->siglock);
217 206 : timer = &tsk->signal->real_timer;
218 206 : if (ovalue) {
219 206 : ovalue->it_value = itimer_get_remtime(timer);
220 206 : ovalue->it_interval
221 206 : = ktime_to_timespec64(tsk->signal->it_real_incr);
222 : }
223 : /* We are sharing ->siglock with it_real_fn() */
224 206 : if (hrtimer_try_to_cancel(timer) < 0) {
225 0 : spin_unlock_irq(&tsk->sighand->siglock);
226 0 : hrtimer_cancel_wait_running(timer);
227 0 : goto again;
228 : }
229 206 : expires = timespec64_to_ktime(value->it_value);
230 206 : if (expires != 0) {
231 92 : tsk->signal->it_real_incr =
232 92 : timespec64_to_ktime(value->it_interval);
233 92 : hrtimer_start(timer, expires, HRTIMER_MODE_REL);
234 : } else
235 114 : tsk->signal->it_real_incr = 0;
236 :
237 206 : trace_itimer_state(ITIMER_REAL, value, 0);
238 206 : spin_unlock_irq(&tsk->sighand->siglock);
239 : break;
240 0 : case ITIMER_VIRTUAL:
241 0 : set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
242 0 : break;
243 0 : case ITIMER_PROF:
244 0 : set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
245 0 : break;
246 : default:
247 : return -EINVAL;
248 : }
249 : return 0;
250 : }
251 :
252 : #ifdef CONFIG_SECURITY_SELINUX
253 : void 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 : */
277 206 : static unsigned int alarm_setitimer(unsigned int seconds)
278 : {
279 206 : struct itimerspec64 it_new, it_old;
280 :
281 : #if BITS_PER_LONG < 64
282 : if (seconds > INT_MAX)
283 : seconds = INT_MAX;
284 : #endif
285 206 : it_new.it_value.tv_sec = seconds;
286 206 : it_new.it_value.tv_nsec = 0;
287 206 : it_new.it_interval.tv_sec = it_new.it_interval.tv_nsec = 0;
288 :
289 206 : 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 : */
295 206 : if ((!it_old.it_value.tv_sec && it_old.it_value.tv_nsec) ||
296 206 : it_old.it_value.tv_nsec >= (NSEC_PER_SEC / 2))
297 88 : it_old.it_value.tv_sec++;
298 :
299 206 : 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 : */
306 412 : SYSCALL_DEFINE1(alarm, unsigned int, seconds)
307 : {
308 206 : return alarm_setitimer(seconds);
309 : }
310 :
311 : #endif
312 :
313 0 : static int get_itimerval(struct itimerspec64 *o, const struct __kernel_old_itimerval __user *i)
314 : {
315 0 : struct __kernel_old_itimerval v;
316 :
317 0 : if (copy_from_user(&v, i, sizeof(struct __kernel_old_itimerval)))
318 : return -EFAULT;
319 :
320 : /* Validate the timevals in value. */
321 0 : if (!timeval_valid(&v.it_value) ||
322 0 : !timeval_valid(&v.it_interval))
323 : return -EINVAL;
324 :
325 0 : o->it_interval.tv_sec = v.it_interval.tv_sec;
326 0 : o->it_interval.tv_nsec = v.it_interval.tv_usec * NSEC_PER_USEC;
327 0 : o->it_value.tv_sec = v.it_value.tv_sec;
328 0 : o->it_value.tv_nsec = v.it_value.tv_usec * NSEC_PER_USEC;
329 0 : return 0;
330 : }
331 :
332 0 : SYSCALL_DEFINE3(setitimer, int, which, struct __kernel_old_itimerval __user *, value,
333 : struct __kernel_old_itimerval __user *, ovalue)
334 : {
335 0 : struct itimerspec64 set_buffer, get_buffer;
336 0 : int error;
337 :
338 0 : if (value) {
339 0 : error = get_itimerval(&set_buffer, value);
340 0 : if (error)
341 0 : return error;
342 : } else {
343 0 : memset(&set_buffer, 0, sizeof(set_buffer));
344 0 : 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 0 : error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
350 0 : if (error || !ovalue)
351 0 : return error;
352 :
353 0 : if (put_itimerval(ovalue, &get_buffer))
354 0 : return -EFAULT;
355 : return 0;
356 : }
357 :
358 : #if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA)
359 0 : static int get_old_itimerval32(struct itimerspec64 *o, const struct old_itimerval32 __user *i)
360 : {
361 0 : struct old_itimerval32 v32;
362 :
363 0 : if (copy_from_user(&v32, i, sizeof(struct old_itimerval32)))
364 : return -EFAULT;
365 :
366 : /* Validate the timevals in value. */
367 0 : if (!timeval_valid(&v32.it_value) ||
368 0 : !timeval_valid(&v32.it_interval))
369 : return -EINVAL;
370 :
371 0 : o->it_interval.tv_sec = v32.it_interval.tv_sec;
372 0 : o->it_interval.tv_nsec = v32.it_interval.tv_usec * NSEC_PER_USEC;
373 0 : o->it_value.tv_sec = v32.it_value.tv_sec;
374 0 : o->it_value.tv_nsec = v32.it_value.tv_usec * NSEC_PER_USEC;
375 0 : return 0;
376 : }
377 :
378 0 : COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
379 : struct old_itimerval32 __user *, value,
380 : struct old_itimerval32 __user *, ovalue)
381 : {
382 0 : struct itimerspec64 set_buffer, get_buffer;
383 0 : int error;
384 :
385 0 : if (value) {
386 0 : error = get_old_itimerval32(&set_buffer, value);
387 0 : if (error)
388 0 : return error;
389 : } else {
390 0 : memset(&set_buffer, 0, sizeof(set_buffer));
391 0 : 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 0 : error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
397 0 : if (error || !ovalue)
398 0 : return error;
399 0 : if (put_old_itimerval32(ovalue, &get_buffer))
400 0 : return -EFAULT;
401 : return 0;
402 : }
403 : #endif
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