/* Copyright (C) 1991-2020 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see . */ #include #include #include #include /* For `struct mutex'. */ #include #include #include #include #include #include #include #include "hurdfault.h" #include "hurdmalloc.h" /* XXX */ #include "../locale/localeinfo.h" #include const char *_hurdsig_getenv (const char *); struct mutex _hurd_siglock; int _hurd_stopped; /* Port that receives signals and other miscellaneous messages. */ mach_port_t _hurd_msgport; /* Thread listening on it. */ thread_t _hurd_msgport_thread; /* These are set up by _hurdsig_init. */ unsigned long int __hurd_sigthread_stack_base; unsigned long int __hurd_sigthread_stack_end; /* Linked-list of per-thread signal state. */ struct hurd_sigstate *_hurd_sigstates; /* Sigstate for the task-global signals. */ struct hurd_sigstate *_hurd_global_sigstate; /* Timeout for RPC's after interrupt_operation. */ mach_msg_timeout_t _hurd_interrupted_rpc_timeout = 60000; static void default_sigaction (struct sigaction actions[NSIG]) { int signo; __sigemptyset (&actions[0].sa_mask); actions[0].sa_flags = SA_RESTART; actions[0].sa_handler = SIG_DFL; for (signo = 1; signo < NSIG; ++signo) actions[signo] = actions[0]; } struct hurd_sigstate * _hurd_thread_sigstate (thread_t thread) { struct hurd_sigstate *ss; __mutex_lock (&_hurd_siglock); for (ss = _hurd_sigstates; ss != NULL; ss = ss->next) if (ss->thread == thread) break; if (ss == NULL) { ss = malloc (sizeof (*ss)); if (ss == NULL) __libc_fatal ("hurd: Can't allocate sigstate\n"); __spin_lock_init (&ss->critical_section_lock); __spin_lock_init (&ss->lock); ss->thread = thread; /* Initialize default state. */ __sigemptyset (&ss->blocked); __sigemptyset (&ss->pending); memset (&ss->sigaltstack, 0, sizeof (ss->sigaltstack)); ss->sigaltstack.ss_flags |= SS_DISABLE; ss->preemptors = NULL; ss->suspended = MACH_PORT_NULL; ss->intr_port = MACH_PORT_NULL; ss->context = NULL; ss->active_resources = NULL; ss->cancel = 0; ss->cancel_hook = NULL; if (thread == MACH_PORT_NULL) { /* Process-wide sigstate, use the system defaults. */ default_sigaction (ss->actions); /* The global sigstate is not added to the _hurd_sigstates list. It is created with _hurd_thread_sigstate (MACH_PORT_NULL) but should be accessed through _hurd_global_sigstate. */ } else { /* Use the global actions as a default for new threads. */ struct hurd_sigstate *s = _hurd_global_sigstate; if (s) { __spin_lock (&s->lock); memcpy (ss->actions, s->actions, sizeof (s->actions)); __spin_unlock (&s->lock); } else default_sigaction (ss->actions); ss->next = _hurd_sigstates; _hurd_sigstates = ss; } } __mutex_unlock (&_hurd_siglock); return ss; } libc_hidden_def (_hurd_thread_sigstate) /* Destroy a sigstate structure. Called by libpthread just before the * corresponding thread is terminated (the kernel thread port must remain valid * until this function is called.) */ void _hurd_sigstate_delete (thread_t thread) { struct hurd_sigstate **ssp, *ss; __mutex_lock (&_hurd_siglock); for (ssp = &_hurd_sigstates; *ssp; ssp = &(*ssp)->next) if ((*ssp)->thread == thread) break; ss = *ssp; if (ss) *ssp = ss->next; __mutex_unlock (&_hurd_siglock); if (ss) free (ss); } /* Make SS a global receiver, with pthread signal semantics. */ void _hurd_sigstate_set_global_rcv (struct hurd_sigstate *ss) { assert (ss->thread != MACH_PORT_NULL); ss->actions[0].sa_handler = SIG_IGN; } /* Check whether SS is a global receiver. */ static int sigstate_is_global_rcv (const struct hurd_sigstate *ss) { return (_hurd_global_sigstate != NULL) && (ss->actions[0].sa_handler == SIG_IGN); } libc_hidden_def (_hurd_sigstate_delete) /* Lock/unlock a hurd_sigstate structure. If the accessors below require it, the global sigstate will be locked as well. */ void _hurd_sigstate_lock (struct hurd_sigstate *ss) { if (sigstate_is_global_rcv (ss)) __spin_lock (&_hurd_global_sigstate->lock); __spin_lock (&ss->lock); } void _hurd_sigstate_unlock (struct hurd_sigstate *ss) { __spin_unlock (&ss->lock); if (sigstate_is_global_rcv (ss)) __spin_unlock (&_hurd_global_sigstate->lock); } libc_hidden_def (_hurd_sigstate_set_global_rcv) /* Retreive a thread's full set of pending signals, including the global ones if appropriate. SS must be locked. */ sigset_t _hurd_sigstate_pending (const struct hurd_sigstate *ss) { sigset_t pending = ss->pending; if (sigstate_is_global_rcv (ss)) __sigorset (&pending, &pending, &_hurd_global_sigstate->pending); return pending; } /* Clear a pending signal and return the associated detailed signal information. SS must be locked, and must have signal SIGNO pending, either directly or through the global sigstate. */ static struct hurd_signal_detail sigstate_clear_pending (struct hurd_sigstate *ss, int signo) { if (sigstate_is_global_rcv (ss) && __sigismember (&_hurd_global_sigstate->pending, signo)) { __sigdelset (&_hurd_global_sigstate->pending, signo); return _hurd_global_sigstate->pending_data[signo]; } assert (__sigismember (&ss->pending, signo)); __sigdelset (&ss->pending, signo); return ss->pending_data[signo]; } libc_hidden_def (_hurd_sigstate_lock) libc_hidden_def (_hurd_sigstate_unlock) /* Retreive a thread's action vector. SS must be locked. */ struct sigaction * _hurd_sigstate_actions (struct hurd_sigstate *ss) { if (sigstate_is_global_rcv (ss)) return _hurd_global_sigstate->actions; else return ss->actions; } libc_hidden_def (_hurd_sigstate_pending) /* Signal delivery itself is on this page. */ #include #include #include #include #include #include #include #include #include #include /* For __msg_sig_post_reply. */ #include #include #include /* Call the crash dump server to mummify us before we die. Returns nonzero if a core file was written. */ static int write_corefile (int signo, const struct hurd_signal_detail *detail) { error_t err; mach_port_t coreserver; file_t file, coredir; const char *name; /* Don't bother locking since we just read the one word. */ rlim_t corelimit = _hurd_rlimits[RLIMIT_CORE].rlim_cur; if (corelimit == 0) /* No core dumping, thank you very much. Note that this makes `ulimit -c 0' prevent crash-suspension too, which is probably what the user wanted. */ return 0; /* XXX RLIMIT_CORE: When we have a protocol to make the server return an error for RLIMIT_FSIZE, then tell the corefile fs server the RLIMIT_CORE value in place of the RLIMIT_FSIZE value. */ /* First get a port to the core dumping server. */ coreserver = MACH_PORT_NULL; name = _hurdsig_getenv ("CRASHSERVER"); if (name != NULL) coreserver = __file_name_lookup (name, 0, 0); if (coreserver == MACH_PORT_NULL) coreserver = __file_name_lookup (_SERVERS_CRASH, 0, 0); if (coreserver == MACH_PORT_NULL) return 0; /* Get a port to the directory where the new core file will reside. */ file = MACH_PORT_NULL; name = _hurdsig_getenv ("COREFILE"); if (name == NULL) name = "core"; coredir = __file_name_split (name, (char **) &name); if (coredir != MACH_PORT_NULL) /* Create the new file, but don't link it into the directory yet. */ __dir_mkfile (coredir, O_WRONLY|O_CREAT, 0600 & ~_hurd_umask, /* XXX ? */ &file); /* Call the core dumping server to write the core file. */ err = __crash_dump_task (coreserver, __mach_task_self (), file, signo, detail->code, detail->error, detail->exc, detail->exc_code, detail->exc_subcode, _hurd_ports[INIT_PORT_CTTYID].port, MACH_MSG_TYPE_COPY_SEND); __mach_port_deallocate (__mach_task_self (), coreserver); if (! err && file != MACH_PORT_NULL) /* The core dump into FILE succeeded, so now link it into the directory. */ err = __dir_link (coredir, file, name, 1); __mach_port_deallocate (__mach_task_self (), file); __mach_port_deallocate (__mach_task_self (), coredir); return !err && file != MACH_PORT_NULL; } /* The lowest-numbered thread state flavor value is 1, so we use bit 0 in machine_thread_all_state.set to record whether we have done thread_abort. */ #define THREAD_ABORTED 1 /* SS->thread is suspended. Abort the thread and get its basic state. */ static void abort_thread (struct hurd_sigstate *ss, struct machine_thread_all_state *state, void (*reply) (void)) { assert (ss->thread != MACH_PORT_NULL); if (!(state->set & THREAD_ABORTED)) { error_t err = __thread_abort (ss->thread); assert_perror (err); /* Clear all thread state flavor set bits, because thread_abort may have changed the state. */ state->set = THREAD_ABORTED; } if (reply) (*reply) (); machine_get_basic_state (ss->thread, state); } /* Find the location of the MiG reply port cell in use by the thread whose state is described by THREAD_STATE. If SIGTHREAD is nonzero, make sure that this location can be set without faulting, or else return NULL. */ static mach_port_t * interrupted_reply_port_location (thread_t thread, struct machine_thread_all_state *thread_state, int sigthread) { mach_port_t *portloc = &THREAD_TCB(thread, thread_state)->reply_port; if (sigthread && _hurdsig_catch_memory_fault (portloc)) /* Faulted trying to read the TCB. */ return NULL; DIAG_PUSH_NEEDS_COMMENT; /* GCC 6 and before seem to be confused by the setjmp call inside _hurdsig_catch_memory_fault and think that we may be returning a second time to here with portloc uninitialized (but we never do). */ DIAG_IGNORE_NEEDS_COMMENT (6, "-Wmaybe-uninitialized"); /* Fault now if this pointer is bogus. */ *(volatile mach_port_t *) portloc = *portloc; DIAG_POP_NEEDS_COMMENT; if (sigthread) _hurdsig_end_catch_fault (); return portloc; } #include #include /* Timeout on interrupt_operation calls. */ mach_msg_timeout_t _hurdsig_interrupt_timeout = 1000; /* SS->thread is suspended. Abort any interruptible RPC operation the thread is doing. This uses only the constant member SS->thread and the unlocked, atomically set member SS->intr_port, so no locking is needed. If successfully sent an interrupt_operation and therefore the thread should wait for its pending RPC to return (possibly EINTR) before taking the incoming signal, returns the reply port to be received on. Otherwise returns MACH_PORT_NULL. SIGNO is used to find the applicable SA_RESTART bit. If SIGNO is zero, the RPC fails with EINTR instead of restarting (thread_cancel). *STATE_CHANGE is set nonzero if STATE->basic was modified and should be applied back to the thread if it might ever run again, else zero. */ mach_port_t _hurdsig_abort_rpcs (struct hurd_sigstate *ss, int signo, int sigthread, struct machine_thread_all_state *state, int *state_change, void (*reply) (void)) { extern const void _hurd_intr_rpc_msg_about_to; extern const void _hurd_intr_rpc_msg_in_trap; mach_port_t rcv_port = MACH_PORT_NULL; mach_port_t intr_port; *state_change = 0; intr_port = ss->intr_port; if (intr_port == MACH_PORT_NULL) /* No interruption needs done. */ return MACH_PORT_NULL; /* Abort the thread's kernel context, so any pending message send or receive completes immediately or aborts. */ abort_thread (ss, state, reply); if (state->basic.PC >= (natural_t) &_hurd_intr_rpc_msg_about_to && state->basic.PC < (natural_t) &_hurd_intr_rpc_msg_in_trap) { /* The thread is about to do the RPC, but hasn't yet entered mach_msg. Mutate the thread's state so it knows not to try the RPC. */ INTR_MSG_BACK_OUT (&state->basic); MACHINE_THREAD_STATE_SET_PC (&state->basic, &_hurd_intr_rpc_msg_in_trap); state->basic.SYSRETURN = MACH_SEND_INTERRUPTED; *state_change = 1; } else if (state->basic.PC == (natural_t) &_hurd_intr_rpc_msg_in_trap /* The thread was blocked in the system call. After thread_abort, the return value register indicates what state the RPC was in when interrupted. */ && state->basic.SYSRETURN == MACH_RCV_INTERRUPTED) { /* The RPC request message was sent and the thread was waiting for the reply message; now the message receive has been aborted, so the mach_msg call will return MACH_RCV_INTERRUPTED. We must tell the server to interrupt the pending operation. The thread must wait for the reply message before running the signal handler (to guarantee that the operation has finished being interrupted), so our nonzero return tells the trampoline code to finish the message receive operation before running the handler. */ mach_port_t *reply = interrupted_reply_port_location (ss->thread, state, sigthread); error_t err = __interrupt_operation (intr_port, _hurdsig_interrupt_timeout); if (err) { if (reply) { /* The interrupt didn't work. Destroy the receive right the thread is blocked on. */ __mach_port_destroy (__mach_task_self (), *reply); *reply = MACH_PORT_NULL; } /* The system call return value register now contains MACH_RCV_INTERRUPTED; when mach_msg resumes, it will retry the call. Since we have just destroyed the receive right, the retry will fail with MACH_RCV_INVALID_NAME. Instead, just change the return value here to EINTR so mach_msg will not retry and the EINTR error code will propagate up. */ state->basic.SYSRETURN = EINTR; *state_change = 1; } else if (reply) rcv_port = *reply; /* All threads whose RPCs were interrupted by the interrupt_operation call above will retry their RPCs unless we clear SS->intr_port. So we clear it for the thread taking a signal when SA_RESTART is clear, so that its call returns EINTR. */ if (! signo || !(_hurd_sigstate_actions (ss) [signo].sa_flags & SA_RESTART)) ss->intr_port = MACH_PORT_NULL; } return rcv_port; } /* Abort the RPCs being run by all threads but this one; all other threads should be suspended. If LIVE is nonzero, those threads may run again, so they should be adjusted as necessary to be happy when resumed. STATE is clobbered as a scratch area; its initial contents are ignored, and its contents on return are not useful. */ static void abort_all_rpcs (int signo, struct machine_thread_all_state *state, int live) { /* We can just loop over the sigstates. Any thread doing something interruptible must have one. We needn't bother locking because all other threads are stopped. */ struct hurd_sigstate *ss; size_t nthreads; mach_port_t *reply_ports; /* First loop over the sigstates to count them. We need to know how big a vector we will need for REPLY_PORTS. */ nthreads = 0; for (ss = _hurd_sigstates; ss != NULL; ss = ss->next) ++nthreads; reply_ports = alloca (nthreads * sizeof *reply_ports); nthreads = 0; for (ss = _hurd_sigstates; ss != NULL; ss = ss->next, ++nthreads) if (ss->thread == _hurd_msgport_thread) reply_ports[nthreads] = MACH_PORT_NULL; else { int state_changed; state->set = 0; /* Reset scratch area. */ /* Abort any operation in progress with interrupt_operation. Record the reply port the thread is waiting on. We will wait for all the replies below. */ reply_ports[nthreads] = _hurdsig_abort_rpcs (ss, signo, 1, state, &state_changed, NULL); if (live) { if (reply_ports[nthreads] != MACH_PORT_NULL) { /* We will wait for the reply to this RPC below, so the thread must issue a new RPC rather than waiting for the reply to the one it sent. */ state->basic.SYSRETURN = EINTR; state_changed = 1; } if (state_changed) /* Aborting the RPC needed to change this thread's state, and it might ever run again. So write back its state. */ __thread_set_state (ss->thread, MACHINE_THREAD_STATE_FLAVOR, (natural_t *) &state->basic, MACHINE_THREAD_STATE_COUNT); } } /* Wait for replies from all the successfully interrupted RPCs. */ while (nthreads-- > 0) if (reply_ports[nthreads] != MACH_PORT_NULL) { error_t err; mach_msg_header_t head; err = __mach_msg (&head, MACH_RCV_MSG|MACH_RCV_TIMEOUT, 0, sizeof head, reply_ports[nthreads], _hurd_interrupted_rpc_timeout, MACH_PORT_NULL); switch (err) { case MACH_RCV_TIMED_OUT: case MACH_RCV_TOO_LARGE: break; default: assert_perror (err); } } } /* Wake up any sigsuspend call that is blocking SS->thread. SS must be locked. */ static void wake_sigsuspend (struct hurd_sigstate *ss) { error_t err; mach_msg_header_t msg; if (ss->suspended == MACH_PORT_NULL) return; /* There is a sigsuspend waiting. Tell it to wake up. */ msg.msgh_bits = MACH_MSGH_BITS (MACH_MSG_TYPE_MAKE_SEND, 0); msg.msgh_remote_port = ss->suspended; msg.msgh_local_port = MACH_PORT_NULL; /* These values do not matter. */ msg.msgh_id = 8675309; /* Jenny, Jenny. */ ss->suspended = MACH_PORT_NULL; err = __mach_msg (&msg, MACH_SEND_MSG, sizeof msg, 0, MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL); assert_perror (err); } struct hurd_signal_preemptor *_hurdsig_preemptors = 0; sigset_t _hurdsig_preempted_set; /* XXX temporary to deal with spelling fix */ weak_alias (_hurdsig_preemptors, _hurdsig_preempters) /* Mask of stop signals. */ #define STOPSIGS (sigmask (SIGTTIN) | sigmask (SIGTTOU) \ | sigmask (SIGSTOP) | sigmask (SIGTSTP)) /* Actual delivery of a single signal. Called with SS unlocked. When the signal is delivered, return SS, locked (or, if SS was originally _hurd_global_sigstate, the sigstate of the actual thread the signal was delivered to). If the signal is being traced, return NULL with SS unlocked. */ static struct hurd_sigstate * post_signal (struct hurd_sigstate *ss, int signo, struct hurd_signal_detail *detail, int untraced, void (*reply) (void)) { struct machine_thread_all_state thread_state; enum { stop, ignore, core, term, handle } act; int ss_suspended; /* Mark the signal as pending. */ void mark_pending (void) { __sigaddset (&ss->pending, signo); /* Save the details to be given to the handler when SIGNO is unblocked. */ ss->pending_data[signo] = *detail; } /* Suspend the process with SIGNO. */ void suspend (void) { /* Stop all other threads and mark ourselves stopped. */ __USEPORT (PROC, ({ /* Hold the siglock while stopping other threads to be sure it is not held by another thread afterwards. */ __mutex_lock (&_hurd_siglock); __proc_dostop (port, _hurd_msgport_thread); __mutex_unlock (&_hurd_siglock); abort_all_rpcs (signo, &thread_state, 1); reply (); __proc_mark_stop (port, signo, detail->code); })); _hurd_stopped = 1; } /* Resume the process after a suspension. */ void resume (void) { /* Resume the process from being stopped. */ thread_t *threads; mach_msg_type_number_t nthreads, i; error_t err; if (! _hurd_stopped) return; /* Tell the proc server we are continuing. */ __USEPORT (PROC, __proc_mark_cont (port)); /* Fetch ports to all our threads and resume them. */ err = __task_threads (__mach_task_self (), &threads, &nthreads); assert_perror (err); for (i = 0; i < nthreads; ++i) { if (act == handle && threads[i] == ss->thread) { /* The thread that will run the handler is kept suspended. */ ss_suspended = 1; } else if (threads[i] != _hurd_msgport_thread) { err = __thread_resume (threads[i]); assert_perror (err); } err = __mach_port_deallocate (__mach_task_self (), threads[i]); assert_perror (err); } __vm_deallocate (__mach_task_self (), (vm_address_t) threads, nthreads * sizeof *threads); _hurd_stopped = 0; } error_t err; sighandler_t handler; if (signo == 0) { if (untraced) { /* This is PTRACE_CONTINUE. */ act = ignore; resume (); } /* This call is just to check for pending signals. */ _hurd_sigstate_lock (ss); return ss; } thread_state.set = 0; /* We know nothing. */ _hurd_sigstate_lock (ss); /* If this is a global signal, try to find a thread ready to accept it right away. This is especially important for untraced signals, since going through the global pending mask would de-untrace them. */ if (ss->thread == MACH_PORT_NULL) { struct hurd_sigstate *rss; __mutex_lock (&_hurd_siglock); for (rss = _hurd_sigstates; rss != NULL; rss = rss->next) { if (! sigstate_is_global_rcv (rss)) continue; /* The global sigstate is already locked. */ __spin_lock (&rss->lock); if (! __sigismember (&rss->blocked, signo)) { ss = rss; break; } __spin_unlock (&rss->lock); } __mutex_unlock (&_hurd_siglock); } /* We want the preemptors to be able to update the blocking mask without affecting the delivery of this signal, so we save the current value to test against later. */ sigset_t blocked = ss->blocked; /* Check for a preempted signal. Preempted signals can arrive during critical sections. */ { inline sighandler_t try_preemptor (struct hurd_signal_preemptor *pe) { /* PE cannot be null. */ do { if (HURD_PREEMPT_SIGNAL_P (pe, signo, detail->code)) { if (pe->preemptor) { sighandler_t handler = (*pe->preemptor) (pe, ss, &signo, detail); if (handler != SIG_ERR) return handler; } else return pe->handler; } pe = pe->next; } while (pe != 0); return SIG_ERR; } handler = ss->preemptors ? try_preemptor (ss->preemptors) : SIG_ERR; /* If no thread-specific preemptor, check for a global one. */ if (handler == SIG_ERR && __sigismember (&_hurdsig_preempted_set, signo)) { __mutex_lock (&_hurd_siglock); handler = try_preemptor (_hurdsig_preemptors); __mutex_unlock (&_hurd_siglock); } } ss_suspended = 0; if (handler == SIG_IGN) /* Ignore the signal altogether. */ act = ignore; else if (handler != SIG_ERR) /* Run the preemption-provided handler. */ act = handle; else { /* No preemption. Do normal handling. */ if (!untraced && __sigismember (&_hurdsig_traced, signo)) { /* We are being traced. Stop to tell the debugger of the signal. */ if (_hurd_stopped) /* Already stopped. Mark the signal as pending; when resumed, we will notice it and stop again. */ mark_pending (); else suspend (); _hurd_sigstate_unlock (ss); reply (); return NULL; } handler = _hurd_sigstate_actions (ss) [signo].sa_handler; if (handler == SIG_DFL) /* Figure out the default action for this signal. */ switch (signo) { case 0: /* A sig_post msg with SIGNO==0 is sent to tell us to check for pending signals. */ act = ignore; break; case SIGTTIN: case SIGTTOU: case SIGSTOP: case SIGTSTP: act = stop; break; case SIGCONT: case SIGIO: case SIGURG: case SIGCHLD: case SIGWINCH: act = ignore; break; case SIGQUIT: case SIGILL: case SIGTRAP: case SIGIOT: case SIGEMT: case SIGFPE: case SIGBUS: case SIGSEGV: case SIGSYS: act = core; break; case SIGINFO: if (_hurd_pgrp == _hurd_pid) { /* We are the process group leader. Since there is no user-specified handler for SIGINFO, we use a default one which prints something interesting. We use the normal handler mechanism instead of just doing it here to avoid the signal thread faulting or blocking in this potentially hairy operation. */ act = handle; handler = _hurd_siginfo_handler; } else act = ignore; break; default: act = term; break; } else if (handler == SIG_IGN) act = ignore; else act = handle; if (__sigmask (signo) & STOPSIGS) /* Stop signals clear a pending SIGCONT even if they are handled or ignored (but not if preempted). */ __sigdelset (&ss->pending, SIGCONT); else { if (signo == SIGCONT) /* Even if handled or ignored (but not preempted), SIGCONT clears stop signals and resumes the process. */ ss->pending &= ~STOPSIGS; if (_hurd_stopped && act != stop && (untraced || signo == SIGCONT)) resume (); } } if (_hurd_orphaned && act == stop && (__sigmask (signo) & (__sigmask (SIGTTIN) | __sigmask (SIGTTOU) | __sigmask (SIGTSTP)))) { /* If we would ordinarily stop for a job control signal, but we are orphaned so noone would ever notice and continue us again, we just quietly die, alone and in the dark. */ detail->code = signo; signo = SIGKILL; act = term; } /* Handle receipt of a blocked signal, or any signal while stopped. */ if (__sigismember (&blocked, signo) || (signo != SIGKILL && _hurd_stopped)) { mark_pending (); act = ignore; } /* Perform the chosen action for the signal. */ switch (act) { case stop: if (_hurd_stopped) { /* We are already stopped, but receiving an untraced stop signal. Instead of resuming and suspending again, just notify the proc server of the new stop signal. */ error_t err = __USEPORT (PROC, __proc_mark_stop (port, signo, detail->code)); assert_perror (err); } else /* Suspend the process. */ suspend (); break; case ignore: if (detail->exc) /* Blocking or ignoring a machine exception is fatal. Otherwise we could just spin on the faulting instruction. */ goto fatal; /* Nobody cares about this signal. If there was a call to resume above in SIGCONT processing and we've left a thread suspended, now's the time to set it going. */ if (ss_suspended) { assert (ss->thread != MACH_PORT_NULL); err = __thread_resume (ss->thread); assert_perror (err); ss_suspended = 0; } break; sigbomb: /* We got a fault setting up the stack frame for the handler. Nothing to do but die; BSD gets SIGILL in this case. */ detail->code = signo; /* XXX ? */ signo = SIGILL; fatal: act = core; /* FALLTHROUGH */ case term: /* Time to die. */ case core: /* And leave a rotting corpse. */ /* Have the proc server stop all other threads in our task. */ err = __USEPORT (PROC, __proc_dostop (port, _hurd_msgport_thread)); assert_perror (err); /* No more user instructions will be executed. The signal can now be considered delivered. */ reply (); /* Abort all server operations now in progress. */ abort_all_rpcs (signo, &thread_state, 0); { int status = W_EXITCODE (0, signo); /* Do a core dump if desired. Only set the wait status bit saying we in fact dumped core if the operation was actually successful. */ if (act == core && write_corefile (signo, detail)) status |= WCOREFLAG; /* Tell proc how we died and then stick the saber in the gut. */ _hurd_exit (status); /* NOTREACHED */ } case handle: /* Call a handler for this signal. */ { struct sigcontext *scp, ocontext; int wait_for_reply, state_changed; assert (ss->thread != MACH_PORT_NULL); /* Stop the thread and abort its pending RPC operations. */ if (! ss_suspended) { err = __thread_suspend (ss->thread); assert_perror (err); } /* Abort the thread's kernel context, so any pending message send or receive completes immediately or aborts. If an interruptible RPC is in progress, abort_rpcs will do this. But we must always do it before fetching the thread's state, because thread_get_state is never kosher before thread_abort. */ abort_thread (ss, &thread_state, NULL); if (ss->context) { /* We have a previous sigcontext that sigreturn was about to restore when another signal arrived. */ mach_port_t *loc; if (_hurdsig_catch_memory_fault (ss->context)) { /* We faulted reading the thread's stack. Forget that context and pretend it wasn't there. It almost certainly crash if this handler returns, but that's it's problem. */ ss->context = NULL; } else { /* Copy the context from the thread's stack before we start diddling the stack to set up the handler. */ ocontext = *ss->context; ss->context = &ocontext; } _hurdsig_end_catch_fault (); if (! machine_get_basic_state (ss->thread, &thread_state)) goto sigbomb; loc = interrupted_reply_port_location (ss->thread, &thread_state, 1); if (loc && *loc != MACH_PORT_NULL) /* This is the reply port for the context which called sigreturn. Since we are abandoning that context entirely and restoring SS->context instead, destroy this port. */ __mach_port_destroy (__mach_task_self (), *loc); /* The thread was in sigreturn, not in any interruptible RPC. */ wait_for_reply = 0; assert (! __spin_lock_locked (&ss->critical_section_lock)); } else { int crit = __spin_lock_locked (&ss->critical_section_lock); wait_for_reply = (_hurdsig_abort_rpcs (ss, /* In a critical section, any RPC should be cancelled instead of restarted, regardless of SA_RESTART, so the entire "atomic" operation can be aborted as a unit. */ crit ? 0 : signo, 1, &thread_state, &state_changed, reply) != MACH_PORT_NULL); if (crit) { /* The thread is in a critical section. Mark the signal as pending. When it finishes the critical section, it will check for pending signals. */ mark_pending (); if (state_changed) /* Some cases of interrupting an RPC must change the thread state to back out the call. Normally this change is rolled into the warping to the handler and sigreturn, but we are not running the handler now because the thread is in a critical section. Instead, mutate the thread right away for the RPC interruption and resume it; the RPC will return early so the critical section can end soon. */ __thread_set_state (ss->thread, MACHINE_THREAD_STATE_FLAVOR, (natural_t *) &thread_state.basic, MACHINE_THREAD_STATE_COUNT); /* */ ss->intr_port = MACH_PORT_NULL; __thread_resume (ss->thread); break; } } /* Call the machine-dependent function to set the thread up to run the signal handler, and preserve its old context. */ scp = _hurd_setup_sighandler (ss, handler, signo, detail, wait_for_reply, &thread_state); if (scp == NULL) goto sigbomb; /* Set the machine-independent parts of the signal context. */ { /* Fetch the thread variable for the MiG reply port, and set it to MACH_PORT_NULL. */ mach_port_t *loc = interrupted_reply_port_location (ss->thread, &thread_state, 1); if (loc) { scp->sc_reply_port = *loc; *loc = MACH_PORT_NULL; } else scp->sc_reply_port = MACH_PORT_NULL; /* Save the intr_port in use by the interrupted code, and clear the cell before running the trampoline. */ scp->sc_intr_port = ss->intr_port; ss->intr_port = MACH_PORT_NULL; if (ss->context) { /* After the handler runs we will restore to the state in SS->context, not the state of the thread now. So restore that context's reply port and intr port. */ scp->sc_reply_port = ss->context->sc_reply_port; scp->sc_intr_port = ss->context->sc_intr_port; ss->context = NULL; } } struct sigaction *action = & _hurd_sigstate_actions (ss) [signo]; /* Backdoor extra argument to signal handler. */ scp->sc_error = detail->error; /* Block requested signals while running the handler. */ scp->sc_mask = ss->blocked; __sigorset (&ss->blocked, &ss->blocked, &action->sa_mask); /* Also block SIGNO unless we're asked not to. */ if (! (action->sa_flags & (SA_RESETHAND | SA_NODEFER))) __sigaddset (&ss->blocked, signo); /* Reset to SIG_DFL if requested. SIGILL and SIGTRAP cannot be automatically reset when delivered; the system silently enforces this restriction. */ if (action->sa_flags & SA_RESETHAND && signo != SIGILL && signo != SIGTRAP) action->sa_handler = SIG_DFL; /* Any sigsuspend call must return after the handler does. */ wake_sigsuspend (ss); /* Start the thread running the handler (or possibly waiting for an RPC reply before running the handler). */ err = __thread_set_state (ss->thread, MACHINE_THREAD_STATE_FLAVOR, (natural_t *) &thread_state.basic, MACHINE_THREAD_STATE_COUNT); assert_perror (err); err = __thread_resume (ss->thread); assert_perror (err); thread_state.set = 0; /* Everything we know is now wrong. */ break; } } return ss; } /* Return the set of pending signals in SS which should be delivered. */ static sigset_t pending_signals (struct hurd_sigstate *ss) { /* We don't worry about any pending signals if we are stopped, nor if SS is in a critical section. We are guaranteed to get a sig_post message before any of them become deliverable: either the SIGCONT signal, or a sig_post with SIGNO==0 as an explicit poll when the thread finishes its critical section. */ if (_hurd_stopped || __spin_lock_locked (&ss->critical_section_lock)) return 0; return _hurd_sigstate_pending (ss) & ~ss->blocked; } /* Post the specified pending signals in SS and return 1. If one of them is traced, abort immediately and return 0. SS must be locked on entry and will be unlocked in all cases. */ static int post_pending (struct hurd_sigstate *ss, sigset_t pending, void (*reply) (void)) { int signo; struct hurd_signal_detail detail; /* Make sure SS corresponds to an actual thread, since we assume it won't change in post_signal. */ assert (ss->thread != MACH_PORT_NULL); for (signo = 1; signo < NSIG; ++signo) if (__sigismember (&pending, signo)) { detail = sigstate_clear_pending (ss, signo); _hurd_sigstate_unlock (ss); /* Will reacquire the lock, except if the signal is traced. */ if (! post_signal (ss, signo, &detail, 0, reply)) return 0; } /* No more signals pending; SS->lock is still locked. */ _hurd_sigstate_unlock (ss); return 1; } /* Post all the pending signals of all threads and return 1. If a traced signal is encountered, abort immediately and return 0. */ static int post_all_pending_signals (void (*reply) (void)) { struct hurd_sigstate *ss; sigset_t pending = 0; for (;;) { __mutex_lock (&_hurd_siglock); for (ss = _hurd_sigstates; ss != NULL; ss = ss->next) { _hurd_sigstate_lock (ss); pending = pending_signals (ss); if (pending) /* post_pending() below will unlock SS. */ break; _hurd_sigstate_unlock (ss); } __mutex_unlock (&_hurd_siglock); if (! pending) return 1; if (! post_pending (ss, pending, reply)) return 0; } } /* Deliver a signal. SS is not locked. */ void _hurd_internal_post_signal (struct hurd_sigstate *ss, int signo, struct hurd_signal_detail *detail, mach_port_t reply_port, mach_msg_type_name_t reply_port_type, int untraced) { /* Reply to this sig_post message. */ __typeof (__msg_sig_post_reply) *reply_rpc = (untraced ? __msg_sig_post_untraced_reply : __msg_sig_post_reply); void reply (void) { error_t err; if (reply_port == MACH_PORT_NULL) return; err = (*reply_rpc) (reply_port, reply_port_type, 0); reply_port = MACH_PORT_NULL; if (err != MACH_SEND_INVALID_DEST) /* Ignore dead reply port. */ assert_perror (err); } ss = post_signal (ss, signo, detail, untraced, reply); if (! ss) return; /* The signal was neither fatal nor traced. We still hold SS->lock. */ if (signo != 0 && ss->thread != MACH_PORT_NULL) { /* The signal has either been ignored or is now being handled. We can consider it delivered and reply to the killer. */ reply (); /* Post any pending signals for this thread. */ if (! post_pending (ss, pending_signals (ss), reply)) return; } else { /* If this was a process-wide signal or a poll request, we need to check for pending signals for all threads. */ _hurd_sigstate_unlock (ss); if (! post_all_pending_signals (reply)) return; /* All pending signals delivered to all threads. Now we can send the reply message even for signal 0. */ reply (); } } /* Decide whether REFPORT enables the sender to send us a SIGNO signal. Returns zero if so, otherwise the error code to return to the sender. */ static error_t signal_allowed (int signo, mach_port_t refport) { if (signo < 0 || signo >= NSIG) return EINVAL; if (refport == __mach_task_self ()) /* Can send any signal. */ goto win; /* Avoid needing to check for this below. */ if (refport == MACH_PORT_NULL) return EPERM; switch (signo) { case SIGINT: case SIGQUIT: case SIGTSTP: case SIGHUP: case SIGINFO: case SIGTTIN: case SIGTTOU: case SIGWINCH: /* Job control signals can be sent by the controlling terminal. */ if (__USEPORT (CTTYID, port == refport)) goto win; break; case SIGCONT: { /* A continue signal can be sent by anyone in the session. */ mach_port_t sessport; if (! __USEPORT (PROC, __proc_getsidport (port, &sessport))) { __mach_port_deallocate (__mach_task_self (), sessport); if (refport == sessport) goto win; } } break; case SIGIO: case SIGURG: { /* Any io object a file descriptor refers to might send us one of these signals using its async ID port for REFPORT. This is pretty wide open; it is not unlikely that some random process can at least open for reading something we have open, get its async ID port, and send us a spurious SIGIO or SIGURG signal. But BSD is actually wider open than that!--you can set the owner of an io object to any process or process group whatsoever and send them gratuitous signals. Someday we could implement some reasonable scheme for authorizing SIGIO and SIGURG signals properly. */ int d; int lucky = 0; /* True if we find a match for REFPORT. */ __mutex_lock (&_hurd_dtable_lock); for (d = 0; !lucky && (unsigned) d < (unsigned) _hurd_dtablesize; ++d) { struct hurd_userlink ulink; io_t port; mach_port_t asyncid; if (_hurd_dtable[d] == NULL) continue; port = _hurd_port_get (&_hurd_dtable[d]->port, &ulink); if (! __io_get_icky_async_id (port, &asyncid)) { if (refport == asyncid) /* Break out of the loop on the next iteration. */ lucky = 1; __mach_port_deallocate (__mach_task_self (), asyncid); } _hurd_port_free (&_hurd_dtable[d]->port, &ulink, port); } __mutex_unlock (&_hurd_dtable_lock); /* If we found a lucky winner, we've set D to -1 in the loop. */ if (lucky) goto win; } } /* If this signal is legit, we have done `goto win' by now. When we return the error, mig deallocates REFPORT. */ return EPERM; win: /* Deallocate the REFPORT send right; we are done with it. */ __mach_port_deallocate (__mach_task_self (), refport); return 0; } /* Implement the sig_post RPC from ; sent when someone wants us to get a signal. */ kern_return_t _S_msg_sig_post (mach_port_t me, mach_port_t reply_port, mach_msg_type_name_t reply_port_type, int signo, natural_t sigcode, mach_port_t refport) { error_t err; struct hurd_signal_detail d; if (err = signal_allowed (signo, refport)) return err; d.code = sigcode; d.exc = 0; /* Post the signal to a global receiver thread (or mark it pending in the global sigstate). This will reply when the signal can be considered delivered. */ _hurd_internal_post_signal (_hurd_global_sigstate, signo, &d, reply_port, reply_port_type, 0); /* Stop if traced. */ return MIG_NO_REPLY; /* Already replied. */ } /* Implement the sig_post_untraced RPC from ; sent when the debugger wants us to really get a signal even if we are traced. */ kern_return_t _S_msg_sig_post_untraced (mach_port_t me, mach_port_t reply_port, mach_msg_type_name_t reply_port_type, int signo, natural_t sigcode, mach_port_t refport) { error_t err; struct hurd_signal_detail d; if (err = signal_allowed (signo, refport)) return err; d.code = sigcode; d.exc = 0; /* Post the signal to the designated signal-receiving thread. This will reply when the signal can be considered delivered. */ _hurd_internal_post_signal (_hurd_global_sigstate, signo, &d, reply_port, reply_port_type, 1); /* Untraced flag. */ return MIG_NO_REPLY; /* Already replied. */ } extern void __mig_init (void *); #include /* Initialize the message port, _hurd_global_sigstate, and start the signal thread. */ void _hurdsig_init (const int *intarray, size_t intarraysize) { error_t err; vm_size_t stacksize; struct hurd_sigstate *ss; __mutex_init (&_hurd_siglock); err = __mach_port_allocate (__mach_task_self (), MACH_PORT_RIGHT_RECEIVE, &_hurd_msgport); assert_perror (err); /* Make a send right to the signal port. */ err = __mach_port_insert_right (__mach_task_self (), _hurd_msgport, _hurd_msgport, MACH_MSG_TYPE_MAKE_SEND); assert_perror (err); /* Initialize the global signal state. */ _hurd_global_sigstate = _hurd_thread_sigstate (MACH_PORT_NULL); /* We block all signals, and let actual threads pull them from the pending mask. */ __sigfillset(& _hurd_global_sigstate->blocked); /* Initialize the main thread's signal state. */ ss = _hurd_self_sigstate (); /* Mark it as a process-wide signal receiver. Threads in this set use the common action vector in _hurd_global_sigstate. */ _hurd_sigstate_set_global_rcv (ss); /* Copy inherited signal settings from our parent (or pre-exec process state) */ if (intarraysize > INIT_SIGMASK) ss->blocked = intarray[INIT_SIGMASK]; if (intarraysize > INIT_SIGPENDING) _hurd_global_sigstate->pending = intarray[INIT_SIGPENDING]; if (intarraysize > INIT_SIGIGN && intarray[INIT_SIGIGN] != 0) { int signo; for (signo = 1; signo < NSIG; ++signo) if (intarray[INIT_SIGIGN] & __sigmask(signo)) _hurd_global_sigstate->actions[signo].sa_handler = SIG_IGN; } /* Start the signal thread listening on the message port. */ #pragma weak __cthread_fork if (!__cthread_fork) { err = __thread_create (__mach_task_self (), &_hurd_msgport_thread); assert_perror (err); stacksize = __vm_page_size * 8; /* Small stack for signal thread. */ err = __mach_setup_thread (__mach_task_self (), _hurd_msgport_thread, _hurd_msgport_receive, (vm_address_t *) &__hurd_sigthread_stack_base, &stacksize); assert_perror (err); err = __mach_setup_tls (_hurd_msgport_thread); assert_perror (err); __hurd_sigthread_stack_end = __hurd_sigthread_stack_base + stacksize; /* Reinitialize the MiG support routines so they will use a per-thread variable for the cached reply port. */ __mig_init ((void *) __hurd_sigthread_stack_base); err = __thread_resume (_hurd_msgport_thread); assert_perror (err); } else { /* When cthreads is being used, we need to make the signal thread a proper cthread. Otherwise it cannot use mutex_lock et al, which will be the cthreads versions. Various of the message port RPC handlers need to take locks, so we need to be able to call into cthreads code and meet its assumptions about how our thread and its stack are arranged. Since cthreads puts it there anyway, we'll let the signal thread's per-thread variables be found as for any normal cthread, and just leave the magic __hurd_sigthread_* values all zero so they'll be ignored. */ #pragma weak __cthread_detach #pragma weak __pthread_getattr_np #pragma weak __pthread_attr_getstack __cthread_t thread = __cthread_fork ( (cthread_fn_t) &_hurd_msgport_receive, 0); __cthread_detach (thread); if (__pthread_getattr_np) { /* Record signal thread stack layout for fork() */ pthread_attr_t attr; void *addr; size_t size; __pthread_getattr_np ((pthread_t) thread, &attr); __pthread_attr_getstack (&attr, &addr, &size); __hurd_sigthread_stack_base = (uintptr_t) addr; __hurd_sigthread_stack_end = __hurd_sigthread_stack_base + size; } /* XXX We need the thread port for the signal thread further on in this thread (see hurdfault.c:_hurdsigfault_init). Therefore we block until _hurd_msgport_thread is initialized by the newly created thread. This really shouldn't be necessary; we should be able to fetch the thread port for a cthread from here. */ while (_hurd_msgport_thread == 0) __swtch_pri (0); } /* Receive exceptions on the signal port. */ #ifdef TASK_EXCEPTION_PORT __task_set_special_port (__mach_task_self (), TASK_EXCEPTION_PORT, _hurd_msgport); #elif defined (EXC_MASK_ALL) __task_set_exception_ports (__mach_task_self (), EXC_MASK_ALL & ~(EXC_MASK_SYSCALL | EXC_MASK_MACH_SYSCALL | EXC_MASK_RPC_ALERT), _hurd_msgport, EXCEPTION_DEFAULT, MACHINE_THREAD_STATE); #else # error task_set_exception_port? #endif /* Sanity check. Any pending, unblocked signals should have been taken by our predecessor incarnation (i.e. parent or pre-exec state) before packing up our init ints. This assert is last (not above) so that signal handling is all set up to handle the abort. */ assert ((ss->pending &~ ss->blocked) == 0); } /* XXXX */ /* Reauthenticate with the proc server. */ static void reauth_proc (mach_port_t new) { mach_port_t ref, ignore; ref = __mach_reply_port (); if (! HURD_PORT_USE (&_hurd_ports[INIT_PORT_PROC], __proc_reauthenticate (port, ref, MACH_MSG_TYPE_MAKE_SEND) || __auth_user_authenticate (new, ref, MACH_MSG_TYPE_MAKE_SEND, &ignore)) && ignore != MACH_PORT_NULL) __mach_port_deallocate (__mach_task_self (), ignore); __mach_port_destroy (__mach_task_self (), ref); /* Set the owner of the process here too. */ __mutex_lock (&_hurd_id.lock); if (!_hurd_check_ids ()) HURD_PORT_USE (&_hurd_ports[INIT_PORT_PROC], __proc_setowner (port, (_hurd_id.gen.nuids ? _hurd_id.gen.uids[0] : 0), !_hurd_id.gen.nuids)); __mutex_unlock (&_hurd_id.lock); (void) &reauth_proc; /* Silence compiler warning. */ } text_set_element (_hurd_reauth_hook, reauth_proc); /* Like `getenv', but safe for the signal thread to run. If the environment is trashed, this will just return NULL. */ const char * _hurdsig_getenv (const char *variable) { if (__libc_enable_secure) return NULL; if (_hurdsig_catch_memory_fault (__environ)) /* We bombed in getenv. */ return NULL; else { const size_t len = strlen (variable); char *value = NULL; char *volatile *ep = __environ; while (*ep) { const char *p = *ep; _hurdsig_fault_preemptor.first = (long int) p; _hurdsig_fault_preemptor.last = VM_MAX_ADDRESS; if (! strncmp (p, variable, len) && p[len] == '=') { size_t valuelen; p += len + 1; valuelen = strlen (p); _hurdsig_fault_preemptor.last = (long int) (p + valuelen); value = malloc (++valuelen); if (value) memcpy (value, p, valuelen); break; } _hurdsig_fault_preemptor.first = (long int) ++ep; _hurdsig_fault_preemptor.last = (long int) (ep + 1); } _hurdsig_end_catch_fault (); return value; } }