/* Copyright (C) 2002-2021 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper , 2002. 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifndef TLS_MULTIPLE_THREADS_IN_TCB /* Pointer to the corresponding variable in libc. */ int *__libc_multiple_threads_ptr attribute_hidden; #endif /* Size and alignment of static TLS block. */ size_t __static_tls_size; size_t __static_tls_align_m1; #ifndef __ASSUME_SET_ROBUST_LIST /* Negative if we do not have the system call and we can use it. */ int __set_robust_list_avail; # define set_robust_list_not_avail() \ __set_robust_list_avail = -1 #else # define set_robust_list_not_avail() do { } while (0) #endif /* Version of the library, used in libthread_db to detect mismatches. */ static const char nptl_version[] __attribute_used__ = VERSION; #ifdef SHARED static #else extern #endif void __nptl_set_robust (struct pthread *); #ifdef SHARED static const struct pthread_functions pthread_functions = { .ptr___pthread_cond_broadcast = __pthread_cond_broadcast, .ptr___pthread_cond_signal = __pthread_cond_signal, .ptr___pthread_cond_wait = __pthread_cond_wait, .ptr___pthread_cond_timedwait = __pthread_cond_timedwait, # if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_3_2) .ptr___pthread_cond_broadcast_2_0 = __pthread_cond_broadcast_2_0, .ptr___pthread_cond_signal_2_0 = __pthread_cond_signal_2_0, .ptr___pthread_cond_wait_2_0 = __pthread_cond_wait_2_0, .ptr___pthread_cond_timedwait_2_0 = __pthread_cond_timedwait_2_0, # endif .ptr_pthread_mutex_destroy = __pthread_mutex_destroy, .ptr_pthread_mutex_init = __pthread_mutex_init, .ptr_pthread_mutex_lock = __pthread_mutex_lock, .ptr_pthread_mutex_unlock = __pthread_mutex_unlock, .ptr___pthread_rwlock_rdlock = __pthread_rwlock_rdlock, .ptr___pthread_rwlock_wrlock = __pthread_rwlock_wrlock, .ptr___pthread_rwlock_unlock = __pthread_rwlock_unlock, .ptr___pthread_key_create = __pthread_key_create, .ptr___pthread_getspecific = __pthread_getspecific, .ptr___pthread_setspecific = __pthread_setspecific, .ptr__nptl_setxid = __nptl_setxid, .ptr_set_robust = __nptl_set_robust }; # define ptr_pthread_functions &pthread_functions #else # define ptr_pthread_functions NULL #endif #ifdef SHARED static #endif void __nptl_set_robust (struct pthread *self) { INTERNAL_SYSCALL_CALL (set_robust_list, &self->robust_head, sizeof (struct robust_list_head)); } /* For asynchronous cancellation we use a signal. This is the handler. */ static void sigcancel_handler (int sig, siginfo_t *si, void *ctx) { /* Safety check. It would be possible to call this function for other signals and send a signal from another process. This is not correct and might even be a security problem. Try to catch as many incorrect invocations as possible. */ if (sig != SIGCANCEL || si->si_pid != __getpid() || si->si_code != SI_TKILL) return; struct pthread *self = THREAD_SELF; int oldval = THREAD_GETMEM (self, cancelhandling); while (1) { /* We are canceled now. When canceled by another thread this flag is already set but if the signal is directly send (internally or from another process) is has to be done here. */ int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK; if (oldval == newval || (oldval & EXITING_BITMASK) != 0) /* Already canceled or exiting. */ break; int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval, oldval); if (curval == oldval) { /* Set the return value. */ THREAD_SETMEM (self, result, PTHREAD_CANCELED); /* Make sure asynchronous cancellation is still enabled. */ if ((newval & CANCELTYPE_BITMASK) != 0) /* Run the registered destructors and terminate the thread. */ __do_cancel (); break; } oldval = curval; } } struct xid_command *__xidcmd attribute_hidden; /* We use the SIGSETXID signal in the setuid, setgid, etc. implementations to tell each thread to call the respective setxid syscall on itself. This is the handler. */ static void sighandler_setxid (int sig, siginfo_t *si, void *ctx) { int result; /* Safety check. It would be possible to call this function for other signals and send a signal from another process. This is not correct and might even be a security problem. Try to catch as many incorrect invocations as possible. */ if (sig != SIGSETXID || si->si_pid != __getpid () || si->si_code != SI_TKILL) return; result = INTERNAL_SYSCALL_NCS (__xidcmd->syscall_no, 3, __xidcmd->id[0], __xidcmd->id[1], __xidcmd->id[2]); int error = 0; if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result))) error = INTERNAL_SYSCALL_ERRNO (result); __nptl_setxid_error (__xidcmd, error); /* Reset the SETXID flag. */ struct pthread *self = THREAD_SELF; int flags, newval; do { flags = THREAD_GETMEM (self, cancelhandling); newval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, flags & ~SETXID_BITMASK, flags); } while (flags != newval); /* And release the futex. */ self->setxid_futex = 1; futex_wake (&self->setxid_futex, 1, FUTEX_PRIVATE); if (atomic_decrement_val (&__xidcmd->cntr) == 0) futex_wake ((unsigned int *) &__xidcmd->cntr, 1, FUTEX_PRIVATE); } /* When using __thread for this, we do it in libc so as not to give libpthread its own TLS segment just for this. */ extern void **__libc_dl_error_tsd (void) __attribute__ ((const)); /* This can be set by the debugger before initialization is complete. */ static bool __nptl_initial_report_events __attribute_used__; void __pthread_initialize_minimal_internal (void) { /* Minimal initialization of the thread descriptor. */ struct pthread *pd = THREAD_SELF; __pthread_initialize_pids (pd); THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]); THREAD_SETMEM (pd, user_stack, true); /* Initialize the robust mutex data. */ { #if __PTHREAD_MUTEX_HAVE_PREV pd->robust_prev = &pd->robust_head; #endif pd->robust_head.list = &pd->robust_head; pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock) - offsetof (pthread_mutex_t, __data.__list.__next)); int res = INTERNAL_SYSCALL_CALL (set_robust_list, &pd->robust_head, sizeof (struct robust_list_head)); if (INTERNAL_SYSCALL_ERROR_P (res)) set_robust_list_not_avail (); } /* Set initial thread's stack block from 0 up to __libc_stack_end. It will be bigger than it actually is, but for unwind.c/pt-longjmp.c purposes this is good enough. */ THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end); /* Before initializing GL (dl_stack_user), the debugger could not find us and had to set __nptl_initial_report_events. Propagate its setting. */ THREAD_SETMEM (pd, report_events, __nptl_initial_report_events); struct sigaction sa; __sigemptyset (&sa.sa_mask); /* Install the cancellation signal handler. If for some reason we cannot install the handler we do not abort. Maybe we should, but it is only asynchronous cancellation which is affected. */ sa.sa_sigaction = sigcancel_handler; sa.sa_flags = SA_SIGINFO; (void) __libc_sigaction (SIGCANCEL, &sa, NULL); /* Install the handle to change the threads' uid/gid. */ sa.sa_sigaction = sighandler_setxid; sa.sa_flags = SA_SIGINFO | SA_RESTART; (void) __libc_sigaction (SIGSETXID, &sa, NULL); /* The parent process might have left the signals blocked. Just in case, unblock it. We reuse the signal mask in the sigaction structure. It is already cleared. */ __sigaddset (&sa.sa_mask, SIGCANCEL); __sigaddset (&sa.sa_mask, SIGSETXID); INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_UNBLOCK, &sa.sa_mask, NULL, __NSIG_BYTES); /* Get the size of the static and alignment requirements for the TLS block. */ size_t static_tls_align; _dl_get_tls_static_info (&__static_tls_size, &static_tls_align); /* Make sure the size takes all the alignments into account. */ if (STACK_ALIGN > static_tls_align) static_tls_align = STACK_ALIGN; __static_tls_align_m1 = static_tls_align - 1; __static_tls_size = roundup (__static_tls_size, static_tls_align); /* Determine the default allowed stack size. This is the size used in case the user does not specify one. */ struct rlimit limit; if (__getrlimit (RLIMIT_STACK, &limit) != 0 || limit.rlim_cur == RLIM_INFINITY) /* The system limit is not usable. Use an architecture-specific default. */ limit.rlim_cur = ARCH_STACK_DEFAULT_SIZE; else if (limit.rlim_cur < PTHREAD_STACK_MIN) /* The system limit is unusably small. Use the minimal size acceptable. */ limit.rlim_cur = PTHREAD_STACK_MIN; /* Make sure it meets the minimum size that allocate_stack (allocatestack.c) will demand, which depends on the page size. */ const uintptr_t pagesz = GLRO(dl_pagesize); const size_t minstack = pagesz + __static_tls_size + MINIMAL_REST_STACK; if (limit.rlim_cur < minstack) limit.rlim_cur = minstack; /* Round the resource limit up to page size. */ limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz); lll_lock (__default_pthread_attr_lock, LLL_PRIVATE); __default_pthread_attr.internal.stacksize = limit.rlim_cur; __default_pthread_attr.internal.guardsize = GLRO (dl_pagesize); lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE); #ifdef SHARED /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock, keep the lock count from the ld.so implementation. */ GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock; GL(dl_rtld_unlock_recursive) = (void *) __pthread_mutex_unlock; unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count; GL(dl_load_lock).mutex.__data.__count = 0; while (rtld_lock_count-- > 0) __pthread_mutex_lock (&GL(dl_load_lock).mutex); GL(dl_make_stack_executable_hook) = &__make_stacks_executable; #endif GL(dl_init_static_tls) = &__pthread_init_static_tls; /* Register the fork generation counter with the libc. */ #ifndef TLS_MULTIPLE_THREADS_IN_TCB __libc_multiple_threads_ptr = #endif __libc_pthread_init (__reclaim_stacks, ptr_pthread_functions); #if HAVE_TUNABLES __pthread_tunables_init (); #endif } strong_alias (__pthread_initialize_minimal_internal, __pthread_initialize_minimal) /* This function is internal (it has a GLIBC_PRIVATE) version, but it is widely used (either via weak symbol, or dlsym) to obtain the __static_tls_size value. This value is then used to adjust the value of the stack size attribute, so that applications receive the full requested stack size, not diminished by the TCB and static TLS allocation on the stack. Once the TCB is separately allocated, this function should be removed or renamed (if it is still necessary at that point). */ size_t __pthread_get_minstack (const pthread_attr_t *attr) { return GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN; }