include/linux/signal.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_SIGNAL_H
   3 #define _LINUX_SIGNAL_H
   4
   5 #include <linux/bug.h>
   6 #include <linux/signal_types.h>
   7 #include <linux/string.h>
   8
   9 struct task_struct;
  10
  11 /* for sysctl */
  12 extern int print_fatal_signals;
  13
  14 static inline void copy_siginfo(kernel_siginfo_t *to,
  15                                 const kernel_siginfo_t *from)
  16 {
  17         memcpy(to, from, sizeof(*to));
  18 }
  19
  20 static inline void clear_siginfo(kernel_siginfo_t *info)
  21 {
  22         memset(info, 0, sizeof(*info));
  23 }
  24
  25 #define SI_EXPANSION_SIZE (sizeof(struct siginfo) - sizeof(struct kernel_siginfo))
  26
  27 static inline void copy_siginfo_to_external(siginfo_t *to,
  28                                             const kernel_siginfo_t *from)
  29 {
  30         memcpy(to, from, sizeof(*from));
  31         memset(((char *)to) + sizeof(struct kernel_siginfo), 0,
  32                 SI_EXPANSION_SIZE);
  33 }
  34
  35 int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from);
  36 int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from);
  37
  38 enum siginfo_layout {
  39         SIL_KILL,
  40         SIL_TIMER,
  41         SIL_POLL,
  42         SIL_FAULT,
  43         SIL_FAULT_MCEERR,
  44         SIL_FAULT_BNDERR,
  45         SIL_FAULT_PKUERR,
  46         SIL_CHLD,
  47         SIL_RT,
  48         SIL_SYS,
  49 };
  50
  51 enum siginfo_layout siginfo_layout(unsigned sig, int si_code);
  52
  53 /*
  54  * Define some primitives to manipulate sigset_t.
  55  */
  56
  57 #ifndef __HAVE_ARCH_SIG_BITOPS
  58 #include <linux/bitops.h>
  59
  60 /* We don't use <linux/bitops.h> for these because there is no need to
  61    be atomic.  */
  62 static inline void sigaddset(sigset_t *set, int _sig)
  63 {
  64         unsigned long sig = _sig - 1;
  65         if (_NSIG_WORDS == 1)
  66                 set->sig[0] |= 1UL << sig;
  67         else
  68                 set->sig[sig / _NSIG_BPW] |= 1UL << (sig % _NSIG_BPW);
  69 }
  70
  71 static inline void sigdelset(sigset_t *set, int _sig)
  72 {
  73         unsigned long sig = _sig - 1;
  74         if (_NSIG_WORDS == 1)
  75                 set->sig[0] &= ~(1UL << sig);
  76         else
  77                 set->sig[sig / _NSIG_BPW] &= ~(1UL << (sig % _NSIG_BPW));
  78 }
  79
  80 static inline int sigismember(sigset_t *set, int _sig)
  81 {
  82         unsigned long sig = _sig - 1;
  83         if (_NSIG_WORDS == 1)
  84                 return 1 & (set->sig[0] >> sig);
  85         else
  86                 return 1 & (set->sig[sig / _NSIG_BPW] >> (sig % _NSIG_BPW));
  87 }
  88
  89 #endif /* __HAVE_ARCH_SIG_BITOPS */
  90
  91 static inline int sigisemptyset(sigset_t *set)
  92 {
  93         switch (_NSIG_WORDS) {
  94         case 4:
  95                 return (set->sig[3] | set->sig[2] |
  96                         set->sig[1] | set->sig[0]) == 0;
  97         case 2:
  98                 return (set->sig[1] | set->sig[0]) == 0;
  99         case 1:
 100                 return set->sig[0] == 0;
 101         default:
 102                 BUILD_BUG();
 103                 return 0;
 104         }
 105 }
 106
 107 static inline int sigequalsets(const sigset_t *set1, const sigset_t *set2)
 108 {
 109         switch (_NSIG_WORDS) {
 110         case 4:
 111                 return  (set1->sig[3] == set2->sig[3]) &&
 112                         (set1->sig[2] == set2->sig[2]) &&
 113                         (set1->sig[1] == set2->sig[1]) &&
 114                         (set1->sig[0] == set2->sig[0]);
 115         case 2:
 116                 return  (set1->sig[1] == set2->sig[1]) &&
 117                         (set1->sig[0] == set2->sig[0]);
 118         case 1:
 119                 return  set1->sig[0] == set2->sig[0];
 120         }
 121         return 0;
 122 }
 123
 124 #define sigmask(sig)    (1UL << ((sig) - 1))
 125
 126 #ifndef __HAVE_ARCH_SIG_SETOPS
 127 #include <linux/string.h>
 128
 129 #define _SIG_SET_BINOP(name, op)                                        \
 130 static inline void name(sigset_t *r, const sigset_t *a, const sigset_t *b) \
 131 {                                                                       \
 132         unsigned long a0, a1, a2, a3, b0, b1, b2, b3;                   \
 133                                                                         \
 134         switch (_NSIG_WORDS) {                                          \
 135         case 4:                                                         \
 136                 a3 = a->sig[3]; a2 = a->sig[2];                         \
 137                 b3 = b->sig[3]; b2 = b->sig[2];                         \
 138                 r->sig[3] = op(a3, b3);                                 \
 139                 r->sig[2] = op(a2, b2);                                 \
 140                 fallthrough;                                            \
 141         case 2:                                                         \
 142                 a1 = a->sig[1]; b1 = b->sig[1];                         \
 143                 r->sig[1] = op(a1, b1);                                 \
 144                 fallthrough;                                            \
 145         case 1:                                                         \
 146                 a0 = a->sig[0]; b0 = b->sig[0];                         \
 147                 r->sig[0] = op(a0, b0);                                 \
 148                 break;                                                  \
 149         default:                                                        \
 150                 BUILD_BUG();                                            \
 151         }                                                               \
 152 }
 153
 154 #define _sig_or(x,y)    ((x) | (y))
 155 _SIG_SET_BINOP(sigorsets, _sig_or)
 156
 157 #define _sig_and(x,y)   ((x) & (y))
 158 _SIG_SET_BINOP(sigandsets, _sig_and)
 159
 160 #define _sig_andn(x,y)  ((x) & ~(y))
 161 _SIG_SET_BINOP(sigandnsets, _sig_andn)
 162
 163 #undef _SIG_SET_BINOP
 164 #undef _sig_or
 165 #undef _sig_and
 166 #undef _sig_andn
 167
 168 #define _SIG_SET_OP(name, op)                                           \
 169 static inline void name(sigset_t *set)                                  \
 170 {                                                                       \
 171         switch (_NSIG_WORDS) {                                          \
 172         case 4: set->sig[3] = op(set->sig[3]);                          \
 173                 set->sig[2] = op(set->sig[2]);                          \
 174                 fallthrough;                                            \
 175         case 2: set->sig[1] = op(set->sig[1]);                          \
 176                 fallthrough;                                            \
 177         case 1: set->sig[0] = op(set->sig[0]);                          \
 178                     break;                                              \
 179         default:                                                        \
 180                 BUILD_BUG();                                            \
 181         }                                                               \
 182 }
 183
 184 #define _sig_not(x)     (~(x))
 185 _SIG_SET_OP(signotset, _sig_not)
 186
 187 #undef _SIG_SET_OP
 188 #undef _sig_not
 189
 190 static inline void sigemptyset(sigset_t *set)
 191 {
 192         switch (_NSIG_WORDS) {
 193         default:
 194                 memset(set, 0, sizeof(sigset_t));
 195                 break;
 196         case 2: set->sig[1] = 0;
 197                 fallthrough;
 198         case 1: set->sig[0] = 0;
 199                 break;
 200         }
 201 }
 202
 203 static inline void sigfillset(sigset_t *set)
 204 {
 205         switch (_NSIG_WORDS) {
 206         default:
 207                 memset(set, -1, sizeof(sigset_t));
 208                 break;
 209         case 2: set->sig[1] = -1;
 210                 fallthrough;
 211         case 1: set->sig[0] = -1;
 212                 break;
 213         }
 214 }
 215
 216 /* Some extensions for manipulating the low 32 signals in particular.  */
 217
 218 static inline void sigaddsetmask(sigset_t *set, unsigned long mask)
 219 {
 220         set->sig[0] |= mask;
 221 }
 222
 223 static inline void sigdelsetmask(sigset_t *set, unsigned long mask)
 224 {
 225         set->sig[0] &= ~mask;
 226 }
 227
 228 static inline int sigtestsetmask(sigset_t *set, unsigned long mask)
 229 {
 230         return (set->sig[0] & mask) != 0;
 231 }
 232
 233 static inline void siginitset(sigset_t *set, unsigned long mask)
 234 {
 235         set->sig[0] = mask;
 236         switch (_NSIG_WORDS) {
 237         default:
 238                 memset(&set->sig[1], 0, sizeof(long)*(_NSIG_WORDS-1));
 239                 break;
 240         case 2: set->sig[1] = 0;
 241                 break;
 242         case 1: ;
 243         }
 244 }
 245
 246 static inline void siginitsetinv(sigset_t *set, unsigned long mask)
 247 {
 248         set->sig[0] = ~mask;
 249         switch (_NSIG_WORDS) {
 250         default:
 251                 memset(&set->sig[1], -1, sizeof(long)*(_NSIG_WORDS-1));
 252                 break;
 253         case 2: set->sig[1] = -1;
 254                 break;
 255         case 1: ;
 256         }
 257 }
 258
 259 #endif /* __HAVE_ARCH_SIG_SETOPS */
 260
 261 static inline void init_sigpending(struct sigpending *sig)
 262 {
 263         sigemptyset(&sig->signal);
 264         INIT_LIST_HEAD(&sig->list);
 265 }
 266
 267 extern void flush_sigqueue(struct sigpending *queue);
 268
 269 /* Test if 'sig' is valid signal. Use this instead of testing _NSIG directly */
 270 static inline int valid_signal(unsigned long sig)
 271 {
 272         return sig <= _NSIG ? 1 : 0;
 273 }
 274
 275 struct timespec;
 276 struct pt_regs;
 277 enum pid_type;
 278
 279 extern int next_signal(struct sigpending *pending, sigset_t *mask);
 280 extern int do_send_sig_info(int sig, struct kernel_siginfo *info,
 281                                 struct task_struct *p, enum pid_type type);
 282 extern int group_send_sig_info(int sig, struct kernel_siginfo *info,
 283                                struct task_struct *p, enum pid_type type);
 284 extern int __group_send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
 285 extern int sigprocmask(int, sigset_t *, sigset_t *);
 286 extern void set_current_blocked(sigset_t *);
 287 extern void __set_current_blocked(const sigset_t *);
 288 extern int show_unhandled_signals;
 289
 290 extern bool get_signal(struct ksignal *ksig);
 291 extern void signal_setup_done(int failed, struct ksignal *ksig, int stepping);
 292 extern void exit_signals(struct task_struct *tsk);
 293 extern void kernel_sigaction(int, __sighandler_t);
 294
 295 #define SIG_KTHREAD ((__force __sighandler_t)2)
 296 #define SIG_KTHREAD_KERNEL ((__force __sighandler_t)3)
 297
 298 static inline void allow_signal(int sig)
 299 {
 300         /*
 301          * Kernel threads handle their own signals. Let the signal code
 302          * know it'll be handled, so that they don't get converted to
 303          * SIGKILL or just silently dropped.
 304          */
 305         kernel_sigaction(sig, SIG_KTHREAD);
 306 }
 307
 308 static inline void allow_kernel_signal(int sig)
 309 {
 310         /*
 311          * Kernel threads handle their own signals. Let the signal code
 312          * know signals sent by the kernel will be handled, so that they
 313          * don't get silently dropped.
 314          */
 315         kernel_sigaction(sig, SIG_KTHREAD_KERNEL);
 316 }
 317
 318 static inline void disallow_signal(int sig)
 319 {
 320         kernel_sigaction(sig, SIG_IGN);
 321 }
 322
 323 extern struct kmem_cache *sighand_cachep;
 324
 325 extern bool unhandled_signal(struct task_struct *tsk, int sig);
 326
 327 /*
 328  * In POSIX a signal is sent either to a specific thread (Linux task)
 329  * or to the process as a whole (Linux thread group).  How the signal
 330  * is sent determines whether it's to one thread or the whole group,
 331  * which determines which signal mask(s) are involved in blocking it
 332  * from being delivered until later.  When the signal is delivered,
 333  * either it's caught or ignored by a user handler or it has a default
 334  * effect that applies to the whole thread group (POSIX process).
 335  *
 336  * The possible effects an unblocked signal set to SIG_DFL can have are:
 337  *   ignore     - Nothing Happens
 338  *   terminate  - kill the process, i.e. all threads in the group,
 339  *                similar to exit_group.  The group leader (only) reports
 340  *                WIFSIGNALED status to its parent.
 341  *   coredump   - write a core dump file describing all threads using
 342  *                the same mm and then kill all those threads
 343  *   stop       - stop all the threads in the group, i.e. TASK_STOPPED state
 344  *
 345  * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
 346  * Other signals when not blocked and set to SIG_DFL behaves as follows.
 347  * The job control signals also have other special effects.
 348  *
 349  *      +--------------------+------------------+
 350  *      |  POSIX signal      |  default action  |
 351  *      +--------------------+------------------+
 352  *      |  SIGHUP            |  terminate       |
 353  *      |  SIGINT            |  terminate       |
 354  *      |  SIGQUIT           |  coredump        |
 355  *      |  SIGILL            |  coredump        |
 356  *      |  SIGTRAP           |  coredump        |
 357  *      |  SIGABRT/SIGIOT    |  coredump        |
 358  *      |  SIGBUS            |  coredump        |
 359  *      |  SIGFPE            |  coredump        |
 360  *      |  SIGKILL           |  terminate(+)    |
 361  *      |  SIGUSR1           |  terminate       |
 362  *      |  SIGSEGV           |  coredump        |
 363  *      |  SIGUSR2           |  terminate       |
 364  *      |  SIGPIPE           |  terminate       |
 365  *      |  SIGALRM           |  terminate       |
 366  *      |  SIGTERM           |  terminate       |
 367  *      |  SIGCHLD           |  ignore          |
 368  *      |  SIGCONT           |  ignore(*)       |
 369  *      |  SIGSTOP           |  stop(*)(+)      |
 370  *      |  SIGTSTP           |  stop(*)         |
 371  *      |  SIGTTIN           |  stop(*)         |
 372  *      |  SIGTTOU           |  stop(*)         |
 373  *      |  SIGURG            |  ignore          |
 374  *      |  SIGXCPU           |  coredump        |
 375  *      |  SIGXFSZ           |  coredump        |
 376  *      |  SIGVTALRM         |  terminate       |
 377  *      |  SIGPROF           |  terminate       |
 378  *      |  SIGPOLL/SIGIO     |  terminate       |
 379  *      |  SIGSYS/SIGUNUSED  |  coredump        |
 380  *      |  SIGSTKFLT         |  terminate       |
 381  *      |  SIGWINCH          |  ignore          |
 382  *      |  SIGPWR            |  terminate       |
 383  *      |  SIGRTMIN-SIGRTMAX |  terminate       |
 384  *      +--------------------+------------------+
 385  *      |  non-POSIX signal  |  default action  |
 386  *      +--------------------+------------------+
 387  *      |  SIGEMT            |  coredump        |
 388  *      +--------------------+------------------+
 389  *
 390  * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
 391  * (*) Special job control effects:
 392  * When SIGCONT is sent, it resumes the process (all threads in the group)
 393  * from TASK_STOPPED state and also clears any pending/queued stop signals
 394  * (any of those marked with "stop(*)").  This happens regardless of blocking,
 395  * catching, or ignoring SIGCONT.  When any stop signal is sent, it clears
 396  * any pending/queued SIGCONT signals; this happens regardless of blocking,
 397  * catching, or ignored the stop signal, though (except for SIGSTOP) the
 398  * default action of stopping the process may happen later or never.
 399  */
 400
 401 #ifdef SIGEMT
 402 #define SIGEMT_MASK     rt_sigmask(SIGEMT)
 403 #else
 404 #define SIGEMT_MASK     0
 405 #endif
 406
 407 #if SIGRTMIN > BITS_PER_LONG
 408 #define rt_sigmask(sig) (1ULL << ((sig)-1))
 409 #else
 410 #define rt_sigmask(sig) sigmask(sig)
 411 #endif
 412
 413 #define siginmask(sig, mask) \
 414         ((sig) > 0 && (sig) < SIGRTMIN && (rt_sigmask(sig) & (mask)))
 415
 416 #define SIG_KERNEL_ONLY_MASK (\
 417         rt_sigmask(SIGKILL)   |  rt_sigmask(SIGSTOP))
 418
 419 #define SIG_KERNEL_STOP_MASK (\
 420         rt_sigmask(SIGSTOP)   |  rt_sigmask(SIGTSTP)   | \
 421         rt_sigmask(SIGTTIN)   |  rt_sigmask(SIGTTOU)   )
 422
 423 #define SIG_KERNEL_COREDUMP_MASK (\
 424         rt_sigmask(SIGQUIT)   |  rt_sigmask(SIGILL)    | \
 425         rt_sigmask(SIGTRAP)   |  rt_sigmask(SIGABRT)   | \
 426         rt_sigmask(SIGFPE)    |  rt_sigmask(SIGSEGV)   | \
 427         rt_sigmask(SIGBUS)    |  rt_sigmask(SIGSYS)    | \
 428         rt_sigmask(SIGXCPU)   |  rt_sigmask(SIGXFSZ)   | \
 429         SIGEMT_MASK                                    )
 430
 431 #define SIG_KERNEL_IGNORE_MASK (\
 432         rt_sigmask(SIGCONT)   |  rt_sigmask(SIGCHLD)   | \
 433         rt_sigmask(SIGWINCH)  |  rt_sigmask(SIGURG)    )
 434
 435 #define SIG_SPECIFIC_SICODES_MASK (\
 436         rt_sigmask(SIGILL)    |  rt_sigmask(SIGFPE)    | \
 437         rt_sigmask(SIGSEGV)   |  rt_sigmask(SIGBUS)    | \
 438         rt_sigmask(SIGTRAP)   |  rt_sigmask(SIGCHLD)   | \
 439         rt_sigmask(SIGPOLL)   |  rt_sigmask(SIGSYS)    | \
 440         SIGEMT_MASK                                    )
 441
 442 #define sig_kernel_only(sig)            siginmask(sig, SIG_KERNEL_ONLY_MASK)
 443 #define sig_kernel_coredump(sig)        siginmask(sig, SIG_KERNEL_COREDUMP_MASK)
 444 #define sig_kernel_ignore(sig)          siginmask(sig, SIG_KERNEL_IGNORE_MASK)
 445 #define sig_kernel_stop(sig)            siginmask(sig, SIG_KERNEL_STOP_MASK)
 446 #define sig_specific_sicodes(sig)       siginmask(sig, SIG_SPECIFIC_SICODES_MASK)
 447
 448 #define sig_fatal(t, signr) \
 449         (!siginmask(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
 450          (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
 451
 452 void signals_init(void);
 453
 454 int restore_altstack(const stack_t __user *);
 455 int __save_altstack(stack_t __user *, unsigned long);
 456
 457 #define unsafe_save_altstack(uss, sp, label) do { \
 458         stack_t __user *__uss = uss; \
 459         struct task_struct *t = current; \
 460         unsafe_put_user((void __user *)t->sas_ss_sp, &__uss->ss_sp, label); \
 461         unsafe_put_user(t->sas_ss_flags, &__uss->ss_flags, label); \
 462         unsafe_put_user(t->sas_ss_size, &__uss->ss_size, label); \
 463         if (t->sas_ss_flags & SS_AUTODISARM) \
 464                 sas_ss_reset(t); \
 465 } while (0);
 466
 467 #ifdef CONFIG_PROC_FS
 468 struct seq_file;
 469 extern void render_sigset_t(struct seq_file *, const char *, sigset_t *);
 470 #endif
 471
 472 #ifndef arch_untagged_si_addr
 473 /*
 474  * Given a fault address and a signal and si_code which correspond to the
 475  * _sigfault union member, returns the address that must appear in si_addr if
 476  * the signal handler does not have SA_EXPOSE_TAGBITS enabled in sa_flags.
 477  */
 478 static inline void __user *arch_untagged_si_addr(void __user *addr,
 479                                                  unsigned long sig,
 480                                                  unsigned long si_code)
 481 {
 482         return addr;
 483 }
 484 #endif
 485
 486 #endif /* _LINUX_SIGNAL_H */