1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_SCHED_SIGNAL_H
3#define _LINUX_SCHED_SIGNAL_H
4
5#include <linux/rculist.h>
6#include <linux/signal.h>
7#include <linux/sched.h>
8#include <linux/sched/jobctl.h>
9#include <linux/sched/task.h>
10#include <linux/cred.h>
11#include <linux/refcount.h>
12
13/*
14 * Types defining task->signal and task->sighand and APIs using them:
15 */
16
17struct sighand_struct {
18 refcount_t count;
19 struct k_sigaction action[_NSIG];
20 spinlock_t siglock;
21 wait_queue_head_t signalfd_wqh;
22};
23
24/*
25 * Per-process accounting stats:
26 */
27struct pacct_struct {
28 int ac_flag;
29 long ac_exitcode;
30 unsigned long ac_mem;
31 u64 ac_utime, ac_stime;
32 unsigned long ac_minflt, ac_majflt;
33};
34
35struct cpu_itimer {
36 u64 expires;
37 u64 incr;
38};
39
40/*
41 * This is the atomic variant of task_cputime, which can be used for
42 * storing and updating task_cputime statistics without locking.
43 */
44struct task_cputime_atomic {
45 atomic64_t utime;
46 atomic64_t stime;
47 atomic64_t sum_exec_runtime;
48};
49
50#define INIT_CPUTIME_ATOMIC \
51 (struct task_cputime_atomic) { \
52 .utime = ATOMIC64_INIT(0), \
53 .stime = ATOMIC64_INIT(0), \
54 .sum_exec_runtime = ATOMIC64_INIT(0), \
55 }
56/**
57 * struct thread_group_cputimer - thread group interval timer counts
58 * @cputime_atomic: atomic thread group interval timers.
59 * @running: true when there are timers running and
60 * @cputime_atomic receives updates.
61 * @checking_timer: true when a thread in the group is in the
62 * process of checking for thread group timers.
63 *
64 * This structure contains the version of task_cputime, above, that is
65 * used for thread group CPU timer calculations.
66 */
67struct thread_group_cputimer {
68 struct task_cputime_atomic cputime_atomic;
69 bool running;
70 bool checking_timer;
71};
72
73struct multiprocess_signals {
74 sigset_t signal;
75 struct hlist_node node;
76};
77
78/*
79 * NOTE! "signal_struct" does not have its own
80 * locking, because a shared signal_struct always
81 * implies a shared sighand_struct, so locking
82 * sighand_struct is always a proper superset of
83 * the locking of signal_struct.
84 */
85struct signal_struct {
86 refcount_t sigcnt;
87 atomic_t live;
88 int nr_threads;
89 struct list_head thread_head;
90
91 wait_queue_head_t wait_chldexit; /* for wait4() */
92
93 /* current thread group signal load-balancing target: */
94 struct task_struct *curr_target;
95
96 /* shared signal handling: */
97 struct sigpending shared_pending;
98
99 /* For collecting multiprocess signals during fork */
100 struct hlist_head multiprocess;
101
102 /* thread group exit support */
103 int group_exit_code;
104 /* overloaded:
105 * - notify group_exit_task when ->count is equal to notify_count
106 * - everyone except group_exit_task is stopped during signal delivery
107 * of fatal signals, group_exit_task processes the signal.
108 */
109 int notify_count;
110 struct task_struct *group_exit_task;
111
112 /* thread group stop support, overloads group_exit_code too */
113 int group_stop_count;
114 unsigned int flags; /* see SIGNAL_* flags below */
115
116 /*
117 * PR_SET_CHILD_SUBREAPER marks a process, like a service
118 * manager, to re-parent orphan (double-forking) child processes
119 * to this process instead of 'init'. The service manager is
120 * able to receive SIGCHLD signals and is able to investigate
121 * the process until it calls wait(). All children of this
122 * process will inherit a flag if they should look for a
123 * child_subreaper process at exit.
124 */
125 unsigned int is_child_subreaper:1;
126 unsigned int has_child_subreaper:1;
127
128#ifdef CONFIG_POSIX_TIMERS
129
130 /* POSIX.1b Interval Timers */
131 int posix_timer_id;
132 struct list_head posix_timers;
133
134 /* ITIMER_REAL timer for the process */
135 struct hrtimer real_timer;
136 ktime_t it_real_incr;
137
138 /*
139 * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
140 * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
141 * values are defined to 0 and 1 respectively
142 */
143 struct cpu_itimer it[2];
144
145 /*
146 * Thread group totals for process CPU timers.
147 * See thread_group_cputimer(), et al, for details.
148 */
149 struct thread_group_cputimer cputimer;
150
151 /* Earliest-expiration cache. */
152 struct task_cputime cputime_expires;
153
154 struct list_head cpu_timers[3];
155
156#endif
157
158 /* PID/PID hash table linkage. */
159 struct pid *pids[PIDTYPE_MAX];
160
161#ifdef CONFIG_NO_HZ_FULL
162 atomic_t tick_dep_mask;
163#endif
164
165 struct pid *tty_old_pgrp;
166
167 /* boolean value for session group leader */
168 int leader;
169
170 struct tty_struct *tty; /* NULL if no tty */
171
172#ifdef CONFIG_SCHED_AUTOGROUP
173 struct autogroup *autogroup;
174#endif
175 /*
176 * Cumulative resource counters for dead threads in the group,
177 * and for reaped dead child processes forked by this group.
178 * Live threads maintain their own counters and add to these
179 * in __exit_signal, except for the group leader.
180 */
181 seqlock_t stats_lock;
182 u64 utime, stime, cutime, cstime;
183 u64 gtime;
184 u64 cgtime;
185 struct prev_cputime prev_cputime;
186 unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
187 unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
188 unsigned long inblock, oublock, cinblock, coublock;
189 unsigned long maxrss, cmaxrss;
190 struct task_io_accounting ioac;
191
192 /*
193 * Cumulative ns of schedule CPU time fo dead threads in the
194 * group, not including a zombie group leader, (This only differs
195 * from jiffies_to_ns(utime + stime) if sched_clock uses something
196 * other than jiffies.)
197 */
198 unsigned long long sum_sched_runtime;
199
200 /*
201 * We don't bother to synchronize most readers of this at all,
202 * because there is no reader checking a limit that actually needs
203 * to get both rlim_cur and rlim_max atomically, and either one
204 * alone is a single word that can safely be read normally.
205 * getrlimit/setrlimit use task_lock(current->group_leader) to
206 * protect this instead of the siglock, because they really
207 * have no need to disable irqs.
208 */
209 struct rlimit rlim[RLIM_NLIMITS];
210
211#ifdef CONFIG_BSD_PROCESS_ACCT
212 struct pacct_struct pacct; /* per-process accounting information */
213#endif
214#ifdef CONFIG_TASKSTATS
215 struct taskstats *stats;
216#endif
217#ifdef CONFIG_AUDIT
218 unsigned audit_tty;
219 struct tty_audit_buf *tty_audit_buf;
220#endif
221
222 /*
223 * Thread is the potential origin of an oom condition; kill first on
224 * oom
225 */
226 bool oom_flag_origin;
227 short oom_score_adj; /* OOM kill score adjustment */
228 short oom_score_adj_min; /* OOM kill score adjustment min value.
229 * Only settable by CAP_SYS_RESOURCE. */
230 struct mm_struct *oom_mm; /* recorded mm when the thread group got
231 * killed by the oom killer */
232
233 struct mutex cred_guard_mutex; /* guard against foreign influences on
234 * credential calculations
235 * (notably. ptrace) */
236} __randomize_layout;
237
238/*
239 * Bits in flags field of signal_struct.
240 */
241#define SIGNAL_STOP_STOPPED 0x00000001 /* job control stop in effect */
242#define SIGNAL_STOP_CONTINUED 0x00000002 /* SIGCONT since WCONTINUED reap */
243#define SIGNAL_GROUP_EXIT 0x00000004 /* group exit in progress */
244#define SIGNAL_GROUP_COREDUMP 0x00000008 /* coredump in progress */
245/*
246 * Pending notifications to parent.
247 */
248#define SIGNAL_CLD_STOPPED 0x00000010
249#define SIGNAL_CLD_CONTINUED 0x00000020
250#define SIGNAL_CLD_MASK (SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
251
252#define SIGNAL_UNKILLABLE 0x00000040 /* for init: ignore fatal signals */
253
254#define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
255 SIGNAL_STOP_CONTINUED)
256
257static inline void signal_set_stop_flags(struct signal_struct *sig,
258 unsigned int flags)
259{
260 WARN_ON(sig->flags & (SIGNAL_GROUP_EXIT|SIGNAL_GROUP_COREDUMP));
261 sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
262}
263
264/* If true, all threads except ->group_exit_task have pending SIGKILL */
265static inline int signal_group_exit(const struct signal_struct *sig)
266{
267 return (sig->flags & SIGNAL_GROUP_EXIT) ||
268 (sig->group_exit_task != NULL);
269}
270
271extern void flush_signals(struct task_struct *);
272extern void ignore_signals(struct task_struct *);
273extern void flush_signal_handlers(struct task_struct *, int force_default);
274extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *info);
275
276static inline int kernel_dequeue_signal(void)
277{
278 struct task_struct *tsk = current;
279 kernel_siginfo_t __info;
280 int ret;
281
282 spin_lock_irq(&tsk->sighand->siglock);
283 ret = dequeue_signal(tsk, &tsk->blocked, &__info);
284 spin_unlock_irq(&tsk->sighand->siglock);
285
286 return ret;
287}
288
289static inline void kernel_signal_stop(void)
290{
291 spin_lock_irq(&current->sighand->siglock);
292 if (current->jobctl & JOBCTL_STOP_DEQUEUED)
293 set_special_state(TASK_STOPPED);
294 spin_unlock_irq(&current->sighand->siglock);
295
296 schedule();
297}
298#ifdef __ARCH_SI_TRAPNO
299# define ___ARCH_SI_TRAPNO(_a1) , _a1
300#else
301# define ___ARCH_SI_TRAPNO(_a1)
302#endif
303#ifdef __ia64__
304# define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
305#else
306# define ___ARCH_SI_IA64(_a1, _a2, _a3)
307#endif
308
309int force_sig_fault(int sig, int code, void __user *addr
310 ___ARCH_SI_TRAPNO(int trapno)
311 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
312 , struct task_struct *t);
313int send_sig_fault(int sig, int code, void __user *addr
314 ___ARCH_SI_TRAPNO(int trapno)
315 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
316 , struct task_struct *t);
317
318int force_sig_mceerr(int code, void __user *, short, struct task_struct *);
319int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
320
321int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
322int force_sig_pkuerr(void __user *addr, u32 pkey);
323
324int force_sig_ptrace_errno_trap(int errno, void __user *addr);
325
326extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
327extern void force_sigsegv(int sig, struct task_struct *p);
328extern int force_sig_info(int, struct kernel_siginfo *, struct task_struct *);
329extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp);
330extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid);
331extern int kill_pid_info_as_cred(int, struct kernel_siginfo *, struct pid *,
332 const struct cred *);
333extern int kill_pgrp(struct pid *pid, int sig, int priv);
334extern int kill_pid(struct pid *pid, int sig, int priv);
335extern __must_check bool do_notify_parent(struct task_struct *, int);
336extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
337extern void force_sig(int, struct task_struct *);
338extern int send_sig(int, struct task_struct *, int);
339extern int zap_other_threads(struct task_struct *p);
340extern struct sigqueue *sigqueue_alloc(void);
341extern void sigqueue_free(struct sigqueue *);
342extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type);
343extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
344
345static inline int restart_syscall(void)
346{
347 set_tsk_thread_flag(current, TIF_SIGPENDING);
348 return -ERESTARTNOINTR;
349}
350
351static inline int signal_pending(struct task_struct *p)
352{
353 return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
354}
355
356static inline int __fatal_signal_pending(struct task_struct *p)
357{
358 return unlikely(sigismember(&p->pending.signal, SIGKILL));
359}
360
361static inline int fatal_signal_pending(struct task_struct *p)
362{
363 return signal_pending(p) && __fatal_signal_pending(p);
364}
365
366static inline int signal_pending_state(long state, struct task_struct *p)
367{
368 if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
369 return 0;
370 if (!signal_pending(p))
371 return 0;
372
373 return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
374}
375
376/*
377 * Reevaluate whether the task has signals pending delivery.
378 * Wake the task if so.
379 * This is required every time the blocked sigset_t changes.
380 * callers must hold sighand->siglock.
381 */
382extern void recalc_sigpending_and_wake(struct task_struct *t);
383extern void recalc_sigpending(void);
384extern void calculate_sigpending(void);
385
386extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
387
388static inline void signal_wake_up(struct task_struct *t, bool resume)
389{
390 signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0);
391}
392static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
393{
394 signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
395}
396
397void task_join_group_stop(struct task_struct *task);
398
399#ifdef TIF_RESTORE_SIGMASK
400/*
401 * Legacy restore_sigmask accessors. These are inefficient on
402 * SMP architectures because they require atomic operations.
403 */
404
405/**
406 * set_restore_sigmask() - make sure saved_sigmask processing gets done
407 *
408 * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
409 * will run before returning to user mode, to process the flag. For
410 * all callers, TIF_SIGPENDING is already set or it's no harm to set
411 * it. TIF_RESTORE_SIGMASK need not be in the set of bits that the
412 * arch code will notice on return to user mode, in case those bits
413 * are scarce. We set TIF_SIGPENDING here to ensure that the arch
414 * signal code always gets run when TIF_RESTORE_SIGMASK is set.
415 */
416static inline void set_restore_sigmask(void)
417{
418 set_thread_flag(TIF_RESTORE_SIGMASK);
419 WARN_ON(!test_thread_flag(TIF_SIGPENDING));
420}
421static inline void clear_restore_sigmask(void)
422{
423 clear_thread_flag(TIF_RESTORE_SIGMASK);
424}
425static inline bool test_restore_sigmask(void)
426{
427 return test_thread_flag(TIF_RESTORE_SIGMASK);
428}
429static inline bool test_and_clear_restore_sigmask(void)
430{
431 return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
432}
433
434#else /* TIF_RESTORE_SIGMASK */
435
436/* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
437static inline void set_restore_sigmask(void)
438{
439 current->restore_sigmask = true;
440 WARN_ON(!test_thread_flag(TIF_SIGPENDING));
441}
442static inline void clear_restore_sigmask(void)
443{
444 current->restore_sigmask = false;
445}
446static inline bool test_restore_sigmask(void)
447{
448 return current->restore_sigmask;
449}
450static inline bool test_and_clear_restore_sigmask(void)
451{
452 if (!current->restore_sigmask)
453 return false;
454 current->restore_sigmask = false;
455 return true;
456}
457#endif
458
459static inline void restore_saved_sigmask(void)
460{
461 if (test_and_clear_restore_sigmask())
462 __set_current_blocked(&current->saved_sigmask);
463}
464
465static inline sigset_t *sigmask_to_save(void)
466{
467 sigset_t *res = &current->blocked;
468 if (unlikely(test_restore_sigmask()))
469 res = &current->saved_sigmask;
470 return res;
471}
472
473static inline int kill_cad_pid(int sig, int priv)
474{
475 return kill_pid(cad_pid, sig, priv);
476}
477
478/* These can be the second arg to send_sig_info/send_group_sig_info. */
479#define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0)
480#define SEND_SIG_PRIV ((struct kernel_siginfo *) 1)
481
482/*
483 * True if we are on the alternate signal stack.
484 */
485static inline int on_sig_stack(unsigned long sp)
486{
487 /*
488 * If the signal stack is SS_AUTODISARM then, by construction, we
489 * can't be on the signal stack unless user code deliberately set
490 * SS_AUTODISARM when we were already on it.
491 *
492 * This improves reliability: if user state gets corrupted such that
493 * the stack pointer points very close to the end of the signal stack,
494 * then this check will enable the signal to be handled anyway.
495 */
496 if (current->sas_ss_flags & SS_AUTODISARM)
497 return 0;
498
499#ifdef CONFIG_STACK_GROWSUP
500 return sp >= current->sas_ss_sp &&
501 sp - current->sas_ss_sp < current->sas_ss_size;
502#else
503 return sp > current->sas_ss_sp &&
504 sp - current->sas_ss_sp <= current->sas_ss_size;
505#endif
506}
507
508static inline int sas_ss_flags(unsigned long sp)
509{
510 if (!current->sas_ss_size)
511 return SS_DISABLE;
512
513 return on_sig_stack(sp) ? SS_ONSTACK : 0;
514}
515
516static inline void sas_ss_reset(struct task_struct *p)
517{
518 p->sas_ss_sp = 0;
519 p->sas_ss_size = 0;
520 p->sas_ss_flags = SS_DISABLE;
521}
522
523static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
524{
525 if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
526#ifdef CONFIG_STACK_GROWSUP
527 return current->sas_ss_sp;
528#else
529 return current->sas_ss_sp + current->sas_ss_size;
530#endif
531 return sp;
532}
533
534extern void __cleanup_sighand(struct sighand_struct *);
535extern void flush_itimer_signals(void);
536
537#define tasklist_empty() \
538 list_empty(&init_task.tasks)
539
540#define next_task(p) \
541 list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
542
543#define for_each_process(p) \
544 for (p = &init_task ; (p = next_task(p)) != &init_task ; )
545
546extern bool current_is_single_threaded(void);
547
548/*
549 * Careful: do_each_thread/while_each_thread is a double loop so
550 * 'break' will not work as expected - use goto instead.
551 */
552#define do_each_thread(g, t) \
553 for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
554
555#define while_each_thread(g, t) \
556 while ((t = next_thread(t)) != g)
557
558#define __for_each_thread(signal, t) \
559 list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)
560
561#define for_each_thread(p, t) \
562 __for_each_thread((p)->signal, t)
563
564/* Careful: this is a double loop, 'break' won't work as expected. */
565#define for_each_process_thread(p, t) \
566 for_each_process(p) for_each_thread(p, t)
567
568typedef int (*proc_visitor)(struct task_struct *p, void *data);
569void walk_process_tree(struct task_struct *top, proc_visitor, void *);
570
571static inline
572struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
573{
574 struct pid *pid;
575 if (type == PIDTYPE_PID)
576 pid = task_pid(task);
577 else
578 pid = task->signal->pids[type];
579 return pid;
580}
581
582static inline struct pid *task_tgid(struct task_struct *task)
583{
584 return task->signal->pids[PIDTYPE_TGID];
585}
586
587/*
588 * Without tasklist or RCU lock it is not safe to dereference
589 * the result of task_pgrp/task_session even if task == current,
590 * we can race with another thread doing sys_setsid/sys_setpgid.
591 */
592static inline struct pid *task_pgrp(struct task_struct *task)
593{
594 return task->signal->pids[PIDTYPE_PGID];
595}
596
597static inline struct pid *task_session(struct task_struct *task)
598{
599 return task->signal->pids[PIDTYPE_SID];
600}
601
602static inline int get_nr_threads(struct task_struct *tsk)
603{
604 return tsk->signal->nr_threads;
605}
606
607static inline bool thread_group_leader(struct task_struct *p)
608{
609 return p->exit_signal >= 0;
610}
611
612/* Do to the insanities of de_thread it is possible for a process
613 * to have the pid of the thread group leader without actually being
614 * the thread group leader. For iteration through the pids in proc
615 * all we care about is that we have a task with the appropriate
616 * pid, we don't actually care if we have the right task.
617 */
618static inline bool has_group_leader_pid(struct task_struct *p)
619{
620 return task_pid(p) == task_tgid(p);
621}
622
623static inline
624bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
625{
626 return p1->signal == p2->signal;
627}
628
629static inline struct task_struct *next_thread(const struct task_struct *p)
630{
631 return list_entry_rcu(p->thread_group.next,
632 struct task_struct, thread_group);
633}
634
635static inline int thread_group_empty(struct task_struct *p)
636{
637 return list_empty(&p->thread_group);
638}
639
640#define delay_group_leader(p) \
641 (thread_group_leader(p) && !thread_group_empty(p))
642
643extern struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
644 unsigned long *flags);
645
646static inline struct sighand_struct *lock_task_sighand(struct task_struct *tsk,
647 unsigned long *flags)
648{
649 struct sighand_struct *ret;
650
651 ret = __lock_task_sighand(tsk, flags);
652 (void)__cond_lock(&tsk->sighand->siglock, ret);
653 return ret;
654}
655
656static inline void unlock_task_sighand(struct task_struct *tsk,
657 unsigned long *flags)
658{
659 spin_unlock_irqrestore(&tsk->sighand->siglock, *flags);
660}
661
662static inline unsigned long task_rlimit(const struct task_struct *tsk,
663 unsigned int limit)
664{
665 return READ_ONCE(tsk->signal->rlim[limit].rlim_cur);
666}
667
668static inline unsigned long task_rlimit_max(const struct task_struct *tsk,
669 unsigned int limit)
670{
671 return READ_ONCE(tsk->signal->rlim[limit].rlim_max);
672}
673
674static inline unsigned long rlimit(unsigned int limit)
675{
676 return task_rlimit(current, limit);
677}
678
679static inline unsigned long rlimit_max(unsigned int limit)
680{
681 return task_rlimit_max(current, limit);
682}
683
684#endif /* _LINUX_SCHED_SIGNAL_H */
685