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 static 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 47 static 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 76 static 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 } 99 100 static int put_itimerval(struct itimerval __user *o, 101 const struct itimerspec64 *i) 102 { 103 struct 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 itimerval)) ? -EFAULT : 0; 110 } 111 112 113 SYSCALL_DEFINE2(getitimer, int, which, struct 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) 124 struct old_itimerval32 { 125 struct old_timeval32 it_interval; 126 struct old_timeval32 it_value; 127 }; 128 129 static 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 } 140 141 COMPAT_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 */ 156 enum 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 } 167 168 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 u64 oval, nval, ointerval, ninterval; 173 struct cpu_itimer *it = &tsk->signal->it[clock_id]; 174 175 /* 176 * Use the to_ktime conversion because that clamps the maximum 177 * value to KTIME_MAX and avoid multiplication overflows. 178 */ 179 nval = timespec64_to_ns(&value->it_value); 180 ninterval = timespec64_to_ns(&value->it_interval); 181 182 spin_lock_irq(&tsk->sighand->siglock); 183 184 oval = it->expires; 185 ointerval = it->incr; 186 if (oval || nval) { 187 if (nval > 0) 188 nval += TICK_NSEC; 189 set_process_cpu_timer(tsk, clock_id, &nval, &oval); 190 } 191 it->expires = nval; 192 it->incr = ninterval; 193 trace_itimer_state(clock_id == CPUCLOCK_VIRT ? 194 ITIMER_VIRTUAL : ITIMER_PROF, value, nval); 195 196 spin_unlock_irq(&tsk->sighand->siglock); 197 198 if (ovalue) { 199 ovalue->it_value = ns_to_timespec64(oval); 200 ovalue->it_interval = ns_to_timespec64(ointerval); 201 } 202 } 203 204 /* 205 * Returns true if the timeval is in canonical form 206 */ 207 #define timeval_valid(t) \ 208 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC)) 209 210 static int do_setitimer(int which, struct itimerspec64 *value, 211 struct itimerspec64 *ovalue) 212 { 213 struct task_struct *tsk = current; 214 struct hrtimer *timer; 215 ktime_t expires; 216 217 switch (which) { 218 case ITIMER_REAL: 219 again: 220 spin_lock_irq(&tsk->sighand->siglock); 221 timer = &tsk->signal->real_timer; 222 if (ovalue) { 223 ovalue->it_value = itimer_get_remtime(timer); 224 ovalue->it_interval 225 = ktime_to_timespec64(tsk->signal->it_real_incr); 226 } 227 /* We are sharing ->siglock with it_real_fn() */ 228 if (hrtimer_try_to_cancel(timer) < 0) { 229 spin_unlock_irq(&tsk->sighand->siglock); 230 hrtimer_cancel_wait_running(timer); 231 goto again; 232 } 233 expires = timespec64_to_ktime(value->it_value); 234 if (expires != 0) { 235 tsk->signal->it_real_incr = 236 timespec64_to_ktime(value->it_interval); 237 hrtimer_start(timer, expires, HRTIMER_MODE_REL); 238 } else 239 tsk->signal->it_real_incr = 0; 240 241 trace_itimer_state(ITIMER_REAL, value, 0); 242 spin_unlock_irq(&tsk->sighand->siglock); 243 break; 244 case ITIMER_VIRTUAL: 245 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue); 246 break; 247 case ITIMER_PROF: 248 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue); 249 break; 250 default: 251 return -EINVAL; 252 } 253 return 0; 254 } 255 256 #ifdef CONFIG_SECURITY_SELINUX 257 void clear_itimer(void) 258 { 259 struct itimerspec64 v = {}; 260 int i; 261 262 for (i = 0; i < 3; i++) 263 do_setitimer(i, &v, NULL); 264 } 265 #endif 266 267 #ifdef __ARCH_WANT_SYS_ALARM 268 269 /** 270 * alarm_setitimer - set alarm in seconds 271 * 272 * @seconds: number of seconds until alarm 273 * 0 disables the alarm 274 * 275 * Returns the remaining time in seconds of a pending timer or 0 when 276 * the timer is not active. 277 * 278 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid 279 * negative timeval settings which would cause immediate expiry. 280 */ 281 static unsigned int alarm_setitimer(unsigned int seconds) 282 { 283 struct itimerspec64 it_new, it_old; 284 285 #if BITS_PER_LONG < 64 286 if (seconds > INT_MAX) 287 seconds = INT_MAX; 288 #endif 289 it_new.it_value.tv_sec = seconds; 290 it_new.it_value.tv_nsec = 0; 291 it_new.it_interval.tv_sec = it_new.it_interval.tv_nsec = 0; 292 293 do_setitimer(ITIMER_REAL, &it_new, &it_old); 294 295 /* 296 * We can't return 0 if we have an alarm pending ... And we'd 297 * better return too much than too little anyway 298 */ 299 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_nsec) || 300 it_old.it_value.tv_nsec >= (NSEC_PER_SEC / 2)) 301 it_old.it_value.tv_sec++; 302 303 return it_old.it_value.tv_sec; 304 } 305 306 /* 307 * For backwards compatibility? This can be done in libc so Alpha 308 * and all newer ports shouldn't need it. 309 */ 310 SYSCALL_DEFINE1(alarm, unsigned int, seconds) 311 { 312 return alarm_setitimer(seconds); 313 } 314 315 #endif 316 317 static int get_itimerval(struct itimerspec64 *o, const struct itimerval __user *i) 318 { 319 struct itimerval v; 320 321 if (copy_from_user(&v, i, sizeof(struct itimerval))) 322 return -EFAULT; 323 324 /* Validate the timevals in value. */ 325 if (!timeval_valid(&v.it_value) || 326 !timeval_valid(&v.it_interval)) 327 return -EINVAL; 328 329 o->it_interval.tv_sec = v.it_interval.tv_sec; 330 o->it_interval.tv_nsec = v.it_interval.tv_usec * NSEC_PER_USEC; 331 o->it_value.tv_sec = v.it_value.tv_sec; 332 o->it_value.tv_nsec = v.it_value.tv_usec * NSEC_PER_USEC; 333 return 0; 334 } 335 336 SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value, 337 struct itimerval __user *, ovalue) 338 { 339 struct itimerspec64 set_buffer, get_buffer; 340 int error; 341 342 if (value) { 343 error = get_itimerval(&set_buffer, value); 344 if (error) 345 return error; 346 } else { 347 memset(&set_buffer, 0, sizeof(set_buffer)); 348 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer." 349 " Misfeature support will be removed\n", 350 current->comm); 351 } 352 353 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL); 354 if (error || !ovalue) 355 return error; 356 357 if (put_itimerval(ovalue, &get_buffer)) 358 return -EFAULT; 359 return 0; 360 } 361 362 #if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA) 363 static int get_old_itimerval32(struct itimerspec64 *o, const struct old_itimerval32 __user *i) 364 { 365 struct old_itimerval32 v32; 366 367 if (copy_from_user(&v32, i, sizeof(struct old_itimerval32))) 368 return -EFAULT; 369 370 /* Validate the timevals in value. */ 371 if (!timeval_valid(&v32.it_value) || 372 !timeval_valid(&v32.it_interval)) 373 return -EINVAL; 374 375 o->it_interval.tv_sec = v32.it_interval.tv_sec; 376 o->it_interval.tv_nsec = v32.it_interval.tv_usec * NSEC_PER_USEC; 377 o->it_value.tv_sec = v32.it_value.tv_sec; 378 o->it_value.tv_nsec = v32.it_value.tv_usec * NSEC_PER_USEC; 379 return 0; 380 } 381 382 COMPAT_SYSCALL_DEFINE3(setitimer, int, which, 383 struct old_itimerval32 __user *, value, 384 struct old_itimerval32 __user *, ovalue) 385 { 386 struct itimerspec64 set_buffer, get_buffer; 387 int error; 388 389 if (value) { 390 error = get_old_itimerval32(&set_buffer, value); 391 if (error) 392 return error; 393 } else { 394 memset(&set_buffer, 0, sizeof(set_buffer)); 395 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer." 396 " Misfeature support will be removed\n", 397 current->comm); 398 } 399 400 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL); 401 if (error || !ovalue) 402 return error; 403 if (put_old_itimerval32(ovalue, &get_buffer)) 404 return -EFAULT; 405 return 0; 406 } 407 #endif 408