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Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001// SPDX-License-Identifier: GPL-2.0
Davide Libenzifba2afa2007-05-10 22:23:13 -07002/*
3 * fs/signalfd.c
4 *
5 * Copyright (C) 2003 Linus Torvalds
6 *
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.
Davide Libenzib8fceee2007-09-20 12:40:16 -070015 * Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
Davi Arnautb3762bf2007-05-23 13:58:04 -070016 * Retrieve multiple signals with one read() call
Davide Libenzib8fceee2007-09-20 12:40:16 -070017 * Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
18 * Attach to the sighand only during read() and poll().
Davide Libenzifba2afa2007-05-10 22:23:13 -070019 */
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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090026#include <linux/slab.h>
Davide Libenzifba2afa2007-05-10 22:23:13 -070027#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>
Adrian Bunk7ec37df2008-02-06 01:36:48 -080032#include <linux/syscalls.h>
Cyrill Gorcunov138d22b2012-12-17 16:05:02 -080033#include <linux/proc_fs.h>
Al Viro7d197ed2013-02-24 01:41:39 -050034#include <linux/compat.h>
Davide Libenzifba2afa2007-05-10 22:23:13 -070035
Oleg Nesterovd80e7312012-02-24 20:07:11 +010036void signalfd_cleanup(struct sighand_struct *sighand)
37{
38 wait_queue_head_t *wqh = &sighand->signalfd_wqh;
Oleg Nesterov971316f2012-02-24 20:07:29 +010039 /*
40 * The lockless check can race with remove_wait_queue() in progress,
41 * but in this case its caller should run under rcu_read_lock() and
Paul E. McKenney5f0d5a32017-01-18 02:53:44 -080042 * sighand_cachep is SLAB_TYPESAFE_BY_RCU, we can safely return.
Oleg Nesterov971316f2012-02-24 20:07:29 +010043 */
Oleg Nesterovd80e7312012-02-24 20:07:11 +010044 if (likely(!waitqueue_active(wqh)))
45 return;
46
Ingo Molnarac6424b2017-06-20 12:06:13 +020047 /* wait_queue_entry_t->func(POLLFREE) should do remove_wait_queue() */
Linus Torvaldsa9a08842018-02-11 14:34:03 -080048 wake_up_poll(wqh, EPOLLHUP | POLLFREE);
Oleg Nesterovd80e7312012-02-24 20:07:11 +010049}
50
Davide Libenzifba2afa2007-05-10 22:23:13 -070051struct signalfd_ctx {
Davide Libenzifba2afa2007-05-10 22:23:13 -070052 sigset_t sigmask;
Davide Libenzifba2afa2007-05-10 22:23:13 -070053};
54
Davide Libenzifba2afa2007-05-10 22:23:13 -070055static int signalfd_release(struct inode *inode, struct file *file)
56{
Davide Libenzib8fceee2007-09-20 12:40:16 -070057 kfree(file->private_data);
Davide Libenzifba2afa2007-05-10 22:23:13 -070058 return 0;
59}
60
Al Viro076ccb72017-07-03 01:02:18 -040061static __poll_t signalfd_poll(struct file *file, poll_table *wait)
Davide Libenzifba2afa2007-05-10 22:23:13 -070062{
63 struct signalfd_ctx *ctx = file->private_data;
Al Viro076ccb72017-07-03 01:02:18 -040064 __poll_t events = 0;
Davide Libenzifba2afa2007-05-10 22:23:13 -070065
Davide Libenzib8fceee2007-09-20 12:40:16 -070066 poll_wait(file, &current->sighand->signalfd_wqh, wait);
Davide Libenzifba2afa2007-05-10 22:23:13 -070067
Davide Libenzib8fceee2007-09-20 12:40:16 -070068 spin_lock_irq(&current->sighand->siglock);
69 if (next_signal(&current->pending, &ctx->sigmask) ||
70 next_signal(&current->signal->shared_pending,
71 &ctx->sigmask))
Linus Torvaldsa9a08842018-02-11 14:34:03 -080072 events |= EPOLLIN;
Davide Libenzib8fceee2007-09-20 12:40:16 -070073 spin_unlock_irq(&current->sighand->siglock);
Davide Libenzifba2afa2007-05-10 22:23:13 -070074
75 return events;
76}
77
78/*
79 * Copied from copy_siginfo_to_user() in kernel/signal.c
80 */
81static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
82 siginfo_t const *kinfo)
83{
Eric W. Biederman5611f552018-04-24 20:39:16 -050084 struct signalfd_siginfo new;
Davide Libenzifba2afa2007-05-10 22:23:13 -070085
86 BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
87
88 /*
Robert P. J. Day14e4a0f2008-02-03 15:12:15 +020089 * Unused members should be zero ...
Davide Libenzifba2afa2007-05-10 22:23:13 -070090 */
Eric W. Biederman5611f552018-04-24 20:39:16 -050091 memset(&new, 0, sizeof(new));
Davide Libenzifba2afa2007-05-10 22:23:13 -070092
93 /*
94 * If you change siginfo_t structure, please be sure
95 * this code is fixed accordingly.
96 */
Eric W. Biederman5611f552018-04-24 20:39:16 -050097 new.ssi_signo = kinfo->si_signo;
98 new.ssi_errno = kinfo->si_errno;
99 new.ssi_code = kinfo->si_code;
Eric W. Biedermancc731522017-07-16 22:36:59 -0500100 switch (siginfo_layout(kinfo->si_signo, kinfo->si_code)) {
101 case SIL_KILL:
Eric W. Biederman5611f552018-04-24 20:39:16 -0500102 new.ssi_pid = kinfo->si_pid;
103 new.ssi_uid = kinfo->si_uid;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700104 break;
Eric W. Biedermancc731522017-07-16 22:36:59 -0500105 case SIL_TIMER:
Eric W. Biederman5611f552018-04-24 20:39:16 -0500106 new.ssi_tid = kinfo->si_tid;
107 new.ssi_overrun = kinfo->si_overrun;
108 new.ssi_ptr = (long) kinfo->si_ptr;
109 new.ssi_int = kinfo->si_int;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700110 break;
Eric W. Biedermancc731522017-07-16 22:36:59 -0500111 case SIL_POLL:
Eric W. Biederman5611f552018-04-24 20:39:16 -0500112 new.ssi_band = kinfo->si_band;
113 new.ssi_fd = kinfo->si_fd;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700114 break;
Eric W. Biederman31931c92018-04-24 20:59:47 -0500115 case SIL_FAULT_BNDERR:
116 case SIL_FAULT_PKUERR:
117 /*
118 * Fall through to the SIL_FAULT case. Both SIL_FAULT_BNDERR
119 * and SIL_FAULT_PKUERR are only generated by faults that
120 * deliver them synchronously to userspace. In case someone
121 * injects one of these signals and signalfd catches it treat
122 * it as SIL_FAULT.
123 */
Eric W. Biedermancc731522017-07-16 22:36:59 -0500124 case SIL_FAULT:
Eric W. Biederman5611f552018-04-24 20:39:16 -0500125 new.ssi_addr = (long) kinfo->si_addr;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700126#ifdef __ARCH_SI_TRAPNO
Eric W. Biederman5611f552018-04-24 20:39:16 -0500127 new.ssi_trapno = kinfo->si_trapno;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700128#endif
Eric W. Biederman31931c92018-04-24 20:59:47 -0500129 break;
130 case SIL_FAULT_MCEERR:
131 new.ssi_addr = (long) kinfo->si_addr;
132#ifdef __ARCH_SI_TRAPNO
133 new.ssi_trapno = kinfo->si_trapno;
134#endif
135 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700136 break;
Eric W. Biedermancc731522017-07-16 22:36:59 -0500137 case SIL_CHLD:
Eric W. Biederman5611f552018-04-24 20:39:16 -0500138 new.ssi_pid = kinfo->si_pid;
139 new.ssi_uid = kinfo->si_uid;
140 new.ssi_status = kinfo->si_status;
141 new.ssi_utime = kinfo->si_utime;
142 new.ssi_stime = kinfo->si_stime;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700143 break;
Eric W. Biedermancc731522017-07-16 22:36:59 -0500144 case SIL_RT:
Davide Libenzi0859ab52008-04-10 21:29:29 -0700145 /*
146 * This case catches also the signals queued by sigqueue().
147 */
Eric W. Biederman5611f552018-04-24 20:39:16 -0500148 new.ssi_pid = kinfo->si_pid;
149 new.ssi_uid = kinfo->si_uid;
150 new.ssi_ptr = (long) kinfo->si_ptr;
151 new.ssi_int = kinfo->si_int;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700152 break;
Eric W. Biederman76b7f672018-04-24 20:48:32 -0500153 case SIL_SYS:
154 new.ssi_call_addr = (long) kinfo->si_call_addr;
155 new.ssi_syscall = kinfo->si_syscall;
156 new.ssi_arch = kinfo->si_arch;
157 break;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700158 }
159
Eric W. Biederman5611f552018-04-24 20:39:16 -0500160 if (copy_to_user(uinfo, &new, sizeof(struct signalfd_siginfo)))
161 return -EFAULT;
162
163 return sizeof(*uinfo);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700164}
165
Davi Arnautb3762bf2007-05-23 13:58:04 -0700166static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
167 int nonblock)
168{
169 ssize_t ret;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700170 DECLARE_WAITQUEUE(wait, current);
171
Davide Libenzib8fceee2007-09-20 12:40:16 -0700172 spin_lock_irq(&current->sighand->siglock);
173 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700174 switch (ret) {
175 case 0:
176 if (!nonblock)
177 break;
178 ret = -EAGAIN;
179 default:
Davide Libenzib8fceee2007-09-20 12:40:16 -0700180 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700181 return ret;
182 }
183
Davide Libenzib8fceee2007-09-20 12:40:16 -0700184 add_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700185 for (;;) {
186 set_current_state(TASK_INTERRUPTIBLE);
Davide Libenzib8fceee2007-09-20 12:40:16 -0700187 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700188 if (ret != 0)
189 break;
190 if (signal_pending(current)) {
191 ret = -ERESTARTSYS;
192 break;
193 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700194 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700195 schedule();
Davide Libenzib8fceee2007-09-20 12:40:16 -0700196 spin_lock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700197 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700198 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700199
Davide Libenzib8fceee2007-09-20 12:40:16 -0700200 remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700201 __set_current_state(TASK_RUNNING);
202
203 return ret;
204}
205
Davide Libenzifba2afa2007-05-10 22:23:13 -0700206/*
Davide Libenzib8fceee2007-09-20 12:40:16 -0700207 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
208 * error code. The "count" parameter must be at least the size of a
209 * "struct signalfd_siginfo".
Davide Libenzifba2afa2007-05-10 22:23:13 -0700210 */
211static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
212 loff_t *ppos)
213{
214 struct signalfd_ctx *ctx = file->private_data;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700215 struct signalfd_siginfo __user *siginfo;
216 int nonblock = file->f_flags & O_NONBLOCK;
217 ssize_t ret, total = 0;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700218 siginfo_t info;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700219
Davi Arnautb3762bf2007-05-23 13:58:04 -0700220 count /= sizeof(struct signalfd_siginfo);
221 if (!count)
Davide Libenzifba2afa2007-05-10 22:23:13 -0700222 return -EINVAL;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700223
Davi Arnautb3762bf2007-05-23 13:58:04 -0700224 siginfo = (struct signalfd_siginfo __user *) buf;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700225 do {
226 ret = signalfd_dequeue(ctx, &info, nonblock);
227 if (unlikely(ret <= 0))
228 break;
229 ret = signalfd_copyinfo(siginfo, &info);
230 if (ret < 0)
231 break;
232 siginfo++;
233 total += ret;
234 nonblock = 1;
235 } while (--count);
236
Davide Libenzib8fceee2007-09-20 12:40:16 -0700237 return total ? total: ret;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700238}
239
Cyrill Gorcunov138d22b2012-12-17 16:05:02 -0800240#ifdef CONFIG_PROC_FS
Joe Perchesa3816ab2014-09-29 16:08:25 -0700241static void signalfd_show_fdinfo(struct seq_file *m, struct file *f)
Cyrill Gorcunov138d22b2012-12-17 16:05:02 -0800242{
243 struct signalfd_ctx *ctx = f->private_data;
244 sigset_t sigmask;
245
246 sigmask = ctx->sigmask;
247 signotset(&sigmask);
248 render_sigset_t(m, "sigmask:\t", &sigmask);
Cyrill Gorcunov138d22b2012-12-17 16:05:02 -0800249}
250#endif
251
Davide Libenzifba2afa2007-05-10 22:23:13 -0700252static const struct file_operations signalfd_fops = {
Cyrill Gorcunov138d22b2012-12-17 16:05:02 -0800253#ifdef CONFIG_PROC_FS
254 .show_fdinfo = signalfd_show_fdinfo,
255#endif
Davide Libenzifba2afa2007-05-10 22:23:13 -0700256 .release = signalfd_release,
257 .poll = signalfd_poll,
258 .read = signalfd_read,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200259 .llseek = noop_llseek,
Davide Libenzifba2afa2007-05-10 22:23:13 -0700260};
261
Al Viro5ed01272018-05-27 08:35:50 -0400262static int do_signalfd4(int ufd, sigset_t *mask, int flags)
Davide Libenzifba2afa2007-05-10 22:23:13 -0700263{
Davide Libenzifba2afa2007-05-10 22:23:13 -0700264 struct signalfd_ctx *ctx;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700265
Ulrich Dreppere38b36f2008-07-23 21:29:42 -0700266 /* Check the SFD_* constants for consistency. */
267 BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
268 BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
269
Ulrich Drepper5fb5e042008-07-23 21:29:37 -0700270 if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
Ulrich Drepper9deb27b2008-07-23 21:29:24 -0700271 return -EINVAL;
272
Al Viro5ed01272018-05-27 08:35:50 -0400273 sigdelsetmask(mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
274 signotset(mask);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700275
276 if (ufd == -1) {
277 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
278 if (!ctx)
279 return -ENOMEM;
280
Al Viro5ed01272018-05-27 08:35:50 -0400281 ctx->sigmask = *mask;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700282
283 /*
284 * When we call this, the initialization must be complete, since
285 * anon_inode_getfd() will install the fd.
286 */
Ulrich Drepper7d9dbca2008-07-23 21:29:22 -0700287 ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
Roland Dreier628ff7c2009-12-18 09:41:24 -0800288 O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
Al Viro2030a422008-02-23 06:46:49 -0500289 if (ufd < 0)
290 kfree(ctx);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700291 } else {
Al Viro2903ff02012-08-28 12:52:22 -0400292 struct fd f = fdget(ufd);
293 if (!f.file)
Davide Libenzifba2afa2007-05-10 22:23:13 -0700294 return -EBADF;
Al Viro2903ff02012-08-28 12:52:22 -0400295 ctx = f.file->private_data;
296 if (f.file->f_op != &signalfd_fops) {
297 fdput(f);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700298 return -EINVAL;
299 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700300 spin_lock_irq(&current->sighand->siglock);
Al Viro5ed01272018-05-27 08:35:50 -0400301 ctx->sigmask = *mask;
Davide Libenzib8fceee2007-09-20 12:40:16 -0700302 spin_unlock_irq(&current->sighand->siglock);
303
304 wake_up(&current->sighand->signalfd_wqh);
Al Viro2903ff02012-08-28 12:52:22 -0400305 fdput(f);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700306 }
307
308 return ufd;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700309}
Ulrich Drepper9deb27b2008-07-23 21:29:24 -0700310
Dominik Brodowski52fb6db2018-03-11 11:34:36 +0100311SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
312 size_t, sizemask, int, flags)
313{
Al Viro5ed01272018-05-27 08:35:50 -0400314 sigset_t mask;
315
316 if (sizemask != sizeof(sigset_t) ||
317 copy_from_user(&mask, user_mask, sizeof(mask)))
318 return -EINVAL;
319 return do_signalfd4(ufd, &mask, flags);
Dominik Brodowski52fb6db2018-03-11 11:34:36 +0100320}
321
Heiko Carstens836f92a2009-01-14 14:14:33 +0100322SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
323 size_t, sizemask)
Ulrich Drepper9deb27b2008-07-23 21:29:24 -0700324{
Al Viro5ed01272018-05-27 08:35:50 -0400325 sigset_t mask;
326
327 if (sizemask != sizeof(sigset_t) ||
328 copy_from_user(&mask, user_mask, sizeof(mask)))
329 return -EINVAL;
330 return do_signalfd4(ufd, &mask, 0);
Ulrich Drepper9deb27b2008-07-23 21:29:24 -0700331}
Al Viro7d197ed2013-02-24 01:41:39 -0500332
333#ifdef CONFIG_COMPAT
Dominik Brodowski570484b2018-03-20 19:36:46 +0100334static long do_compat_signalfd4(int ufd,
Al Viro5ed01272018-05-27 08:35:50 -0400335 const compat_sigset_t __user *user_mask,
Dominik Brodowski570484b2018-03-20 19:36:46 +0100336 compat_size_t sigsetsize, int flags)
Al Viro7d197ed2013-02-24 01:41:39 -0500337{
Al Viro5ed01272018-05-27 08:35:50 -0400338 sigset_t mask;
Al Viro7d197ed2013-02-24 01:41:39 -0500339
340 if (sigsetsize != sizeof(compat_sigset_t))
341 return -EINVAL;
Al Viro5ed01272018-05-27 08:35:50 -0400342 if (get_compat_sigset(&mask, user_mask))
Al Viro7d197ed2013-02-24 01:41:39 -0500343 return -EFAULT;
Al Viro5ed01272018-05-27 08:35:50 -0400344 return do_signalfd4(ufd, &mask, flags);
Al Viro7d197ed2013-02-24 01:41:39 -0500345}
346
Dominik Brodowski570484b2018-03-20 19:36:46 +0100347COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd,
Al Viro5ed01272018-05-27 08:35:50 -0400348 const compat_sigset_t __user *, user_mask,
Dominik Brodowski570484b2018-03-20 19:36:46 +0100349 compat_size_t, sigsetsize,
350 int, flags)
351{
Al Viro5ed01272018-05-27 08:35:50 -0400352 return do_compat_signalfd4(ufd, user_mask, sigsetsize, flags);
Dominik Brodowski570484b2018-03-20 19:36:46 +0100353}
354
Al Viro7d197ed2013-02-24 01:41:39 -0500355COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd,
Al Viro5ed01272018-05-27 08:35:50 -0400356 const compat_sigset_t __user *, user_mask,
Al Viro7d197ed2013-02-24 01:41:39 -0500357 compat_size_t, sigsetsize)
358{
Al Viro5ed01272018-05-27 08:35:50 -0400359 return do_compat_signalfd4(ufd, user_mask, sigsetsize, 0);
Al Viro7d197ed2013-02-24 01:41:39 -0500360}
361#endif