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1// SPDX-License-Identifier: GPL-2.02/*3 * fs/signalfd.c4 *5 * Copyright (C) 2003 Linus Torvalds6 *7 * Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org>8 * Changed ->read() to return a siginfo strcture instead of signal number.9 * Fixed locking in ->poll().10 * Added sighand-detach notification.11 * Added fd re-use in sys_signalfd() syscall.12 * Now using anonymous inode source.13 * Thanks to Oleg Nesterov for useful code review and suggestions.14 * More comments and suggestions from Arnd Bergmann.15 * Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>16 * Retrieve multiple signals with one read() call17 * Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>18 * Attach to the sighand only during read() and poll().19 */20 21#include <linux/file.h>22#include <linux/poll.h>23#include <linux/init.h>24#include <linux/fs.h>25#include <linux/sched.h>26#include <linux/slab.h>27#include <linux/kernel.h>28#include <linux/signal.h>29#include <linux/list.h>30#include <linux/anon_inodes.h>31#include <linux/signalfd.h>32#include <linux/syscalls.h>33#include <linux/proc_fs.h>34#include <linux/compat.h>35 36void signalfd_cleanup(struct sighand_struct *sighand)37{38 wake_up_pollfree(&sighand->signalfd_wqh);39}40 41struct signalfd_ctx {42 sigset_t sigmask;43};44 45static int signalfd_release(struct inode *inode, struct file *file)46{47 kfree(file->private_data);48 return 0;49}50 51static __poll_t signalfd_poll(struct file *file, poll_table *wait)52{53 struct signalfd_ctx *ctx = file->private_data;54 __poll_t events = 0;55 56 poll_wait(file, ¤t->sighand->signalfd_wqh, wait);57 58 spin_lock_irq(¤t->sighand->siglock);59 if (next_signal(¤t->pending, &ctx->sigmask) ||60 next_signal(¤t->signal->shared_pending,61 &ctx->sigmask))62 events |= EPOLLIN;63 spin_unlock_irq(¤t->sighand->siglock);64 65 return events;66}67 68/*69 * Copied from copy_siginfo_to_user() in kernel/signal.c70 */71static int signalfd_copyinfo(struct iov_iter *to, kernel_siginfo_t const *kinfo)72{73 struct signalfd_siginfo new;74 75 BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);76 77 /*78 * Unused members should be zero ...79 */80 memset(&new, 0, sizeof(new));81 82 /*83 * If you change siginfo_t structure, please be sure84 * this code is fixed accordingly.85 */86 new.ssi_signo = kinfo->si_signo;87 new.ssi_errno = kinfo->si_errno;88 new.ssi_code = kinfo->si_code;89 switch (siginfo_layout(kinfo->si_signo, kinfo->si_code)) {90 case SIL_KILL:91 new.ssi_pid = kinfo->si_pid;92 new.ssi_uid = kinfo->si_uid;93 break;94 case SIL_TIMER:95 new.ssi_tid = kinfo->si_tid;96 new.ssi_overrun = kinfo->si_overrun;97 new.ssi_ptr = (long) kinfo->si_ptr;98 new.ssi_int = kinfo->si_int;99 break;100 case SIL_POLL:101 new.ssi_band = kinfo->si_band;102 new.ssi_fd = kinfo->si_fd;103 break;104 case SIL_FAULT_BNDERR:105 case SIL_FAULT_PKUERR:106 case SIL_FAULT_PERF_EVENT:107 /*108 * Fall through to the SIL_FAULT case. SIL_FAULT_BNDERR,109 * SIL_FAULT_PKUERR, and SIL_FAULT_PERF_EVENT are only110 * generated by faults that deliver them synchronously to111 * userspace. In case someone injects one of these signals112 * and signalfd catches it treat it as SIL_FAULT.113 */114 case SIL_FAULT:115 new.ssi_addr = (long) kinfo->si_addr;116 break;117 case SIL_FAULT_TRAPNO:118 new.ssi_addr = (long) kinfo->si_addr;119 new.ssi_trapno = kinfo->si_trapno;120 break;121 case SIL_FAULT_MCEERR:122 new.ssi_addr = (long) kinfo->si_addr;123 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;124 break;125 case SIL_CHLD:126 new.ssi_pid = kinfo->si_pid;127 new.ssi_uid = kinfo->si_uid;128 new.ssi_status = kinfo->si_status;129 new.ssi_utime = kinfo->si_utime;130 new.ssi_stime = kinfo->si_stime;131 break;132 case SIL_RT:133 /*134 * This case catches also the signals queued by sigqueue().135 */136 new.ssi_pid = kinfo->si_pid;137 new.ssi_uid = kinfo->si_uid;138 new.ssi_ptr = (long) kinfo->si_ptr;139 new.ssi_int = kinfo->si_int;140 break;141 case SIL_SYS:142 new.ssi_call_addr = (long) kinfo->si_call_addr;143 new.ssi_syscall = kinfo->si_syscall;144 new.ssi_arch = kinfo->si_arch;145 break;146 }147 148 if (!copy_to_iter_full(&new, sizeof(struct signalfd_siginfo), to))149 return -EFAULT;150 151 return sizeof(struct signalfd_siginfo);152}153 154static HWJS_SUSPENDS ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, kernel_siginfo_t *info,155 int nonblock)156{157 enum pid_type type;158 ssize_t ret;159 DECLARE_WAITQUEUE(wait, current);160 161 spin_lock_irq(¤t->sighand->siglock);162 ret = dequeue_signal(&ctx->sigmask, info, &type);163 switch (ret) {164 case 0:165 if (!nonblock)166 break;167 ret = -EAGAIN;168 fallthrough;169 default:170 spin_unlock_irq(¤t->sighand->siglock);171 return ret;172 }173 174 add_wait_queue(¤t->sighand->signalfd_wqh, &wait);175 for (;;) {176 set_current_state(TASK_INTERRUPTIBLE);177 ret = dequeue_signal(&ctx->sigmask, info, &type);178 if (ret != 0)179 break;180 if (signal_pending(current)) {181 ret = -ERESTARTSYS;182 break;183 }184 spin_unlock_irq(¤t->sighand->siglock);185 schedule();186 spin_lock_irq(¤t->sighand->siglock);187 }188 spin_unlock_irq(¤t->sighand->siglock);189 190 remove_wait_queue(¤t->sighand->signalfd_wqh, &wait);191 __set_current_state(TASK_RUNNING);192 193 return ret;194}195 196/*197 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative198 * error code. The "count" parameter must be at least the size of a199 * "struct signalfd_siginfo".200 */201static HWJS_SUSPENDS ssize_t signalfd_read_iter(struct kiocb *iocb, struct iov_iter *to)202{203 struct file *file = iocb->ki_filp;204 struct signalfd_ctx *ctx = file->private_data;205 size_t count = iov_iter_count(to);206 ssize_t ret, total = 0;207 kernel_siginfo_t info;208 bool nonblock;209 210 count /= sizeof(struct signalfd_siginfo);211 if (!count)212 return -EINVAL;213 214 nonblock = file->f_flags & O_NONBLOCK || iocb->ki_flags & IOCB_NOWAIT;215 do {216 ret = signalfd_dequeue(ctx, &info, nonblock);217 if (unlikely(ret <= 0))218 break;219 ret = signalfd_copyinfo(to, &info);220 if (ret < 0)221 break;222 total += ret;223 nonblock = 1;224 } while (--count);225 226 return total ? total: ret;227}228 229#ifdef CONFIG_PROC_FS230static void signalfd_show_fdinfo(struct seq_file *m, struct file *f)231{232 struct signalfd_ctx *ctx = f->private_data;233 sigset_t sigmask;234 235 sigmask = ctx->sigmask;236 signotset(&sigmask);237 render_sigset_t(m, "sigmask:\t", &sigmask);238}239#endif240 241static const struct file_operations signalfd_fops = {242#ifdef CONFIG_PROC_FS243 .show_fdinfo = signalfd_show_fdinfo,244#endif245 .release = signalfd_release,246 .poll = signalfd_poll,247 .read_iter = signalfd_read_iter,248 .llseek = noop_llseek,249};250 251static HWJS_SUSPENDS int do_signalfd4(int ufd, sigset_t *mask, int flags)252{253 struct signalfd_ctx *ctx;254 255 /* Check the SFD_* constants for consistency. */256 BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);257 BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);258 259 if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))260 return -EINVAL;261 262 sigdelsetmask(mask, sigmask(SIGKILL) | sigmask(SIGSTOP));263 signotset(mask);264 265 if (ufd == -1) {266 struct file *file;267 268 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);269 if (!ctx)270 return -ENOMEM;271 272 ctx->sigmask = *mask;273 274 ufd = get_unused_fd_flags(flags & O_CLOEXEC);275 if (ufd < 0) {276 kfree(ctx);277 return ufd;278 }279 280 file = anon_inode_getfile("[signalfd]", &signalfd_fops, ctx,281 O_RDWR | (flags & O_NONBLOCK));282 if (IS_ERR(file)) {283 put_unused_fd(ufd);284 kfree(ctx);285 return PTR_ERR(file);286 }287 file->f_mode |= FMODE_NOWAIT;288 289 fd_install(ufd, file);290 } else {291 struct fd f = fdget(ufd);292 if (!fd_file(f))293 return -EBADF;294 ctx = fd_file(f)->private_data;295 if (fd_file(f)->f_op != &signalfd_fops) {296 fdput(f);297 return -EINVAL;298 }299 spin_lock_irq(¤t->sighand->siglock);300 ctx->sigmask = *mask;301 spin_unlock_irq(¤t->sighand->siglock);302 303 wake_up(¤t->sighand->signalfd_wqh);304 fdput(f);305 }306 307 return ufd;308}309 310SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,311 size_t, sizemask, int, flags)312{313 sigset_t mask;314 315 if (sizemask != sizeof(sigset_t))316 return -EINVAL;317 if (copy_from_user(&mask, user_mask, sizeof(mask)))318 return -EFAULT;319 return do_signalfd4(ufd, &mask, flags);320}321 322SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,323 size_t, sizemask)324{325 sigset_t mask;326 327 if (sizemask != sizeof(sigset_t))328 return -EINVAL;329 if (copy_from_user(&mask, user_mask, sizeof(mask)))330 return -EFAULT;331 return do_signalfd4(ufd, &mask, 0);332}333 334#ifdef CONFIG_COMPAT335static long do_compat_signalfd4(int ufd,336 const compat_sigset_t __user *user_mask,337 compat_size_t sigsetsize, int flags)338{339 sigset_t mask;340 341 if (sigsetsize != sizeof(compat_sigset_t))342 return -EINVAL;343 if (get_compat_sigset(&mask, user_mask))344 return -EFAULT;345 return do_signalfd4(ufd, &mask, flags);346}347 348COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd,349 const compat_sigset_t __user *, user_mask,350 compat_size_t, sigsetsize,351 int, flags)352{353 return do_compat_signalfd4(ufd, user_mask, sigsetsize, flags);354}355 356COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd,357 const compat_sigset_t __user *, user_mask,358 compat_size_t, sigsetsize)359{360 return do_compat_signalfd4(ufd, user_mask, sigsetsize, 0);361}362#endif363