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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
1/*
2 * linux/kernel/itimer.c
3 *
4 * Copyright (C) 1992 Darren Senn
5 */
6
7/* These are all the functions necessary to implement itimers */
8
9#include <linux/mm.h>
10#include <linux/interrupt.h>
11#include <linux/syscalls.h>
12#include <linux/time.h>
13#include <linux/posix-timers.h>
14#include <linux/hrtimer.h>
15#include <trace/events/timer.h>
16
17#include <asm/uaccess.h>
18
19/**
20 * itimer_get_remtime - get remaining time for the timer
21 *
22 * @timer: the timer to read
23 *
24 * Returns the delta between the expiry time and now, which can be
25 * less than zero or 1usec for an pending expired timer
26 */
27static struct timeval itimer_get_remtime(struct hrtimer *timer)
28{
29 ktime_t rem = __hrtimer_get_remaining(timer, true);
30
31 /*
32 * Racy but safe: if the itimer expires after the above
33 * hrtimer_get_remtime() call but before this condition
34 * then we return 0 - which is correct.
35 */
36 if (hrtimer_active(timer)) {
37 if (rem.tv64 <= 0)
38 rem.tv64 = NSEC_PER_USEC;
39 } else
40 rem.tv64 = 0;
41
42 return ktime_to_timeval(rem);
43}
44
45static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
46 struct itimerval *const value)
47{
48 cputime_t cval, cinterval;
49 struct cpu_itimer *it = &tsk->signal->it[clock_id];
50
51 spin_lock_irq(&tsk->sighand->siglock);
52
53 cval = it->expires;
54 cinterval = it->incr;
55 if (cval) {
56 struct task_cputime cputime;
57 cputime_t t;
58
59 thread_group_cputimer(tsk, &cputime);
60 if (clock_id == CPUCLOCK_PROF)
61 t = cputime.utime + cputime.stime;
62 else
63 /* CPUCLOCK_VIRT */
64 t = cputime.utime;
65
66 if (cval < t)
67 /* about to fire */
68 cval = cputime_one_jiffy;
69 else
70 cval = cval - t;
71 }
72
73 spin_unlock_irq(&tsk->sighand->siglock);
74
75 cputime_to_timeval(cval, &value->it_value);
76 cputime_to_timeval(cinterval, &value->it_interval);
77}
78
79int do_getitimer(int which, struct itimerval *value)
80{
81 struct task_struct *tsk = current;
82
83 switch (which) {
84 case ITIMER_REAL:
85 spin_lock_irq(&tsk->sighand->siglock);
86 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
87 value->it_interval =
88 ktime_to_timeval(tsk->signal->it_real_incr);
89 spin_unlock_irq(&tsk->sighand->siglock);
90 break;
91 case ITIMER_VIRTUAL:
92 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
93 break;
94 case ITIMER_PROF:
95 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
96 break;
97 default:
98 return(-EINVAL);
99 }
100 return 0;
101}
102
103SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
104{
105 int error = -EFAULT;
106 struct itimerval get_buffer;
107
108 if (value) {
109 error = do_getitimer(which, &get_buffer);
110 if (!error &&
111 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
112 error = -EFAULT;
113 }
114 return error;
115}
116
117
118/*
119 * The timer is automagically restarted, when interval != 0
120 */
121enum hrtimer_restart it_real_fn(struct hrtimer *timer)
122{
123 struct signal_struct *sig =
124 container_of(timer, struct signal_struct, real_timer);
125
126 trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
127 kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
128
129 return HRTIMER_NORESTART;
130}
131
132static inline u32 cputime_sub_ns(cputime_t ct, s64 real_ns)
133{
134 struct timespec ts;
135 s64 cpu_ns;
136
137 cputime_to_timespec(ct, &ts);
138 cpu_ns = timespec_to_ns(&ts);
139
140 return (cpu_ns <= real_ns) ? 0 : cpu_ns - real_ns;
141}
142
143static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
144 const struct itimerval *const value,
145 struct itimerval *const ovalue)
146{
147 cputime_t cval, nval, cinterval, ninterval;
148 s64 ns_ninterval, ns_nval;
149 u32 error, incr_error;
150 struct cpu_itimer *it = &tsk->signal->it[clock_id];
151
152 nval = timeval_to_cputime(&value->it_value);
153 ns_nval = timeval_to_ns(&value->it_value);
154 ninterval = timeval_to_cputime(&value->it_interval);
155 ns_ninterval = timeval_to_ns(&value->it_interval);
156
157 error = cputime_sub_ns(nval, ns_nval);
158 incr_error = cputime_sub_ns(ninterval, ns_ninterval);
159
160 spin_lock_irq(&tsk->sighand->siglock);
161
162 cval = it->expires;
163 cinterval = it->incr;
164 if (cval || nval) {
165 if (nval > 0)
166 nval += cputime_one_jiffy;
167 set_process_cpu_timer(tsk, clock_id, &nval, &cval);
168 }
169 it->expires = nval;
170 it->incr = ninterval;
171 it->error = error;
172 it->incr_error = incr_error;
173 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
174 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
175
176 spin_unlock_irq(&tsk->sighand->siglock);
177
178 if (ovalue) {
179 cputime_to_timeval(cval, &ovalue->it_value);
180 cputime_to_timeval(cinterval, &ovalue->it_interval);
181 }
182}
183
184/*
185 * Returns true if the timeval is in canonical form
186 */
187#define timeval_valid(t) \
188 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
189
190int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
191{
192 struct task_struct *tsk = current;
193 struct hrtimer *timer;
194 ktime_t expires;
195
196 /*
197 * Validate the timevals in value.
198 */
199 if (!timeval_valid(&value->it_value) ||
200 !timeval_valid(&value->it_interval))
201 return -EINVAL;
202
203 switch (which) {
204 case ITIMER_REAL:
205again:
206 spin_lock_irq(&tsk->sighand->siglock);
207 timer = &tsk->signal->real_timer;
208 if (ovalue) {
209 ovalue->it_value = itimer_get_remtime(timer);
210 ovalue->it_interval
211 = ktime_to_timeval(tsk->signal->it_real_incr);
212 }
213 /* We are sharing ->siglock with it_real_fn() */
214 if (hrtimer_try_to_cancel(timer) < 0) {
215 spin_unlock_irq(&tsk->sighand->siglock);
216 goto again;
217 }
218 expires = timeval_to_ktime(value->it_value);
219 if (expires.tv64 != 0) {
220 tsk->signal->it_real_incr =
221 timeval_to_ktime(value->it_interval);
222 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
223 } else
224 tsk->signal->it_real_incr.tv64 = 0;
225
226 trace_itimer_state(ITIMER_REAL, value, 0);
227 spin_unlock_irq(&tsk->sighand->siglock);
228 break;
229 case ITIMER_VIRTUAL:
230 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
231 break;
232 case ITIMER_PROF:
233 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
234 break;
235 default:
236 return -EINVAL;
237 }
238 return 0;
239}
240
241/**
242 * alarm_setitimer - set alarm in seconds
243 *
244 * @seconds: number of seconds until alarm
245 * 0 disables the alarm
246 *
247 * Returns the remaining time in seconds of a pending timer or 0 when
248 * the timer is not active.
249 *
250 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
251 * negative timeval settings which would cause immediate expiry.
252 */
253unsigned int alarm_setitimer(unsigned int seconds)
254{
255 struct itimerval it_new, it_old;
256
257#if BITS_PER_LONG < 64
258 if (seconds > INT_MAX)
259 seconds = INT_MAX;
260#endif
261 it_new.it_value.tv_sec = seconds;
262 it_new.it_value.tv_usec = 0;
263 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
264
265 do_setitimer(ITIMER_REAL, &it_new, &it_old);
266
267 /*
268 * We can't return 0 if we have an alarm pending ... And we'd
269 * better return too much than too little anyway
270 */
271 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
272 it_old.it_value.tv_usec >= 500000)
273 it_old.it_value.tv_sec++;
274
275 return it_old.it_value.tv_sec;
276}
277
278SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
279 struct itimerval __user *, ovalue)
280{
281 struct itimerval set_buffer, get_buffer;
282 int error;
283
284 if (value) {
285 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
286 return -EFAULT;
287 } else {
288 memset(&set_buffer, 0, sizeof(set_buffer));
289 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
290 " Misfeature support will be removed\n",
291 current->comm);
292 }
293
294 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
295 if (error || !ovalue)
296 return error;
297
298 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
299 return -EFAULT;
300 return 0;
301}