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 timeval 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_timeval(rem); 45 } 46 47 static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id, 48 struct itimerval *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_timeval(val); 73 value->it_interval = ns_to_timeval(interval); 74 } 75 76 static int do_getitimer(int which, struct itimerval *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_timeval(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 SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value) 101 { 102 int error = -EFAULT; 103 struct itimerval get_buffer; 104 105 if (value) { 106 error = do_getitimer(which, &get_buffer); 107 if (!error && 108 copy_to_user(value, &get_buffer, sizeof(get_buffer))) 109 error = -EFAULT; 110 } 111 return error; 112 } 113 114 #if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA) 115 struct old_itimerval32 { 116 struct old_timeval32 it_interval; 117 struct old_timeval32 it_value; 118 }; 119 120 static int put_old_itimerval32(struct old_itimerval32 __user *o, const struct itimerval *i) 121 { 122 struct old_itimerval32 v32; 123 124 v32.it_interval.tv_sec = i->it_interval.tv_sec; 125 v32.it_interval.tv_usec = i->it_interval.tv_usec; 126 v32.it_value.tv_sec = i->it_value.tv_sec; 127 v32.it_value.tv_usec = i->it_value.tv_usec; 128 return copy_to_user(o, &v32, sizeof(struct old_itimerval32)) ? -EFAULT : 0; 129 } 130 131 COMPAT_SYSCALL_DEFINE2(getitimer, int, which, 132 struct old_itimerval32 __user *, it) 133 { 134 struct itimerval kit; 135 int error = do_getitimer(which, &kit); 136 137 if (!error && put_old_itimerval32(it, &kit)) 138 error = -EFAULT; 139 return error; 140 } 141 #endif 142 143 /* 144 * The timer is automagically restarted, when interval != 0 145 */ 146 enum hrtimer_restart it_real_fn(struct hrtimer *timer) 147 { 148 struct signal_struct *sig = 149 container_of(timer, struct signal_struct, real_timer); 150 struct pid *leader_pid = sig->pids[PIDTYPE_TGID]; 151 152 trace_itimer_expire(ITIMER_REAL, leader_pid, 0); 153 kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid); 154 155 return HRTIMER_NORESTART; 156 } 157 158 static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id, 159 const struct itimerval *const value, 160 struct itimerval *const ovalue) 161 { 162 u64 oval, nval, ointerval, ninterval; 163 struct cpu_itimer *it = &tsk->signal->it[clock_id]; 164 165 /* 166 * Use the to_ktime conversion because that clamps the maximum 167 * value to KTIME_MAX and avoid multiplication overflows. 168 */ 169 nval = ktime_to_ns(timeval_to_ktime(value->it_value)); 170 ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval)); 171 172 spin_lock_irq(&tsk->sighand->siglock); 173 174 oval = it->expires; 175 ointerval = it->incr; 176 if (oval || nval) { 177 if (nval > 0) 178 nval += TICK_NSEC; 179 set_process_cpu_timer(tsk, clock_id, &nval, &oval); 180 } 181 it->expires = nval; 182 it->incr = ninterval; 183 trace_itimer_state(clock_id == CPUCLOCK_VIRT ? 184 ITIMER_VIRTUAL : ITIMER_PROF, value, nval); 185 186 spin_unlock_irq(&tsk->sighand->siglock); 187 188 if (ovalue) { 189 ovalue->it_value = ns_to_timeval(oval); 190 ovalue->it_interval = ns_to_timeval(ointerval); 191 } 192 } 193 194 /* 195 * Returns true if the timeval is in canonical form 196 */ 197 #define timeval_valid(t) \ 198 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC)) 199 200 static int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue) 201 { 202 struct task_struct *tsk = current; 203 struct hrtimer *timer; 204 ktime_t expires; 205 206 /* 207 * Validate the timevals in value. 208 */ 209 if (!timeval_valid(&value->it_value) || 210 !timeval_valid(&value->it_interval)) 211 return -EINVAL; 212 213 switch (which) { 214 case ITIMER_REAL: 215 again: 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_timeval(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 = timeval_to_ktime(value->it_value); 230 if (expires != 0) { 231 tsk->signal->it_real_incr = 232 timeval_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 253 void clear_itimer(void) 254 { 255 struct itimerval 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 static unsigned int alarm_setitimer(unsigned int seconds) 278 { 279 struct itimerval 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_usec = 0; 287 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 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_usec) || 296 it_old.it_value.tv_usec >= 500000) 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 */ 306 SYSCALL_DEFINE1(alarm, unsigned int, seconds) 307 { 308 return alarm_setitimer(seconds); 309 } 310 311 #endif 312 313 SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value, 314 struct itimerval __user *, ovalue) 315 { 316 struct itimerval set_buffer, get_buffer; 317 int error; 318 319 if (value) { 320 if(copy_from_user(&set_buffer, value, sizeof(set_buffer))) 321 return -EFAULT; 322 } else { 323 memset(&set_buffer, 0, sizeof(set_buffer)); 324 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer." 325 " Misfeature support will be removed\n", 326 current->comm); 327 } 328 329 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL); 330 if (error || !ovalue) 331 return error; 332 333 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer))) 334 return -EFAULT; 335 return 0; 336 } 337 338 #if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA) 339 static int get_old_itimerval32(struct itimerval *o, const struct old_itimerval32 __user *i) 340 { 341 struct old_itimerval32 v32; 342 343 if (copy_from_user(&v32, i, sizeof(struct old_itimerval32))) 344 return -EFAULT; 345 o->it_interval.tv_sec = v32.it_interval.tv_sec; 346 o->it_interval.tv_usec = v32.it_interval.tv_usec; 347 o->it_value.tv_sec = v32.it_value.tv_sec; 348 o->it_value.tv_usec = v32.it_value.tv_usec; 349 return 0; 350 } 351 352 COMPAT_SYSCALL_DEFINE3(setitimer, int, which, 353 struct old_itimerval32 __user *, in, 354 struct old_itimerval32 __user *, out) 355 { 356 struct itimerval kin, kout; 357 int error; 358 359 if (in) { 360 if (get_old_itimerval32(&kin, in)) 361 return -EFAULT; 362 } else { 363 memset(&kin, 0, sizeof(kin)); 364 } 365 366 error = do_setitimer(which, &kin, out ? &kout : NULL); 367 if (error || !out) 368 return error; 369 if (put_old_itimerval32(out, &kout)) 370 return -EFAULT; 371 return 0; 372 } 373 #endif 374