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b2441318 1// SPDX-License-Identifier: GPL-2.0
fba2afaa
DL
2/*
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.
b8fceee1 15 * Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
b3762bfc 16 * Retrieve multiple signals with one read() call
b8fceee1
DL
17 * Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
18 * Attach to the sighand only during read() and poll().
fba2afaa
DL
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>
5a0e3ad6 26#include <linux/slab.h>
fba2afaa
DL
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>
7ec37dfd 32#include <linux/syscalls.h>
138d22b5 33#include <linux/proc_fs.h>
7d197ed4 34#include <linux/compat.h>
fba2afaa 35
d80e731e
ON
36void signalfd_cleanup(struct sighand_struct *sighand)
37{
38 wait_queue_head_t *wqh = &sighand->signalfd_wqh;
971316f0
ON
39 /*
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
5f0d5a3a 42 * sighand_cachep is SLAB_TYPESAFE_BY_RCU, we can safely return.
971316f0 43 */
d80e731e
ON
44 if (likely(!waitqueue_active(wqh)))
45 return;
46
ac6424b9 47 /* wait_queue_entry_t->func(POLLFREE) should do remove_wait_queue() */
a9a08845 48 wake_up_poll(wqh, EPOLLHUP | POLLFREE);
d80e731e
ON
49}
50
fba2afaa 51struct signalfd_ctx {
fba2afaa 52 sigset_t sigmask;
fba2afaa
DL
53};
54
fba2afaa
DL
55static int signalfd_release(struct inode *inode, struct file *file)
56{
b8fceee1 57 kfree(file->private_data);
fba2afaa
DL
58 return 0;
59}
60
076ccb76 61static __poll_t signalfd_poll(struct file *file, poll_table *wait)
fba2afaa
DL
62{
63 struct signalfd_ctx *ctx = file->private_data;
076ccb76 64 __poll_t events = 0;
fba2afaa 65
b8fceee1 66 poll_wait(file, &current->sighand->signalfd_wqh, wait);
fba2afaa 67
b8fceee1
DL
68 spin_lock_irq(&current->sighand->siglock);
69 if (next_signal(&current->pending, &ctx->sigmask) ||
70 next_signal(&current->signal->shared_pending,
71 &ctx->sigmask))
a9a08845 72 events |= EPOLLIN;
b8fceee1 73 spin_unlock_irq(&current->sighand->siglock);
fba2afaa
DL
74
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,
ae7795bc 82 kernel_siginfo_t const *kinfo)
fba2afaa 83{
5611f55e 84 struct signalfd_siginfo new;
fba2afaa
DL
85
86 BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
87
88 /*
14e4a0f2 89 * Unused members should be zero ...
fba2afaa 90 */
5611f55e 91 memset(&new, 0, sizeof(new));
fba2afaa
DL
92
93 /*
94 * If you change siginfo_t structure, please be sure
95 * this code is fixed accordingly.
96 */
5611f55e
EB
97 new.ssi_signo = kinfo->si_signo;
98 new.ssi_errno = kinfo->si_errno;
99 new.ssi_code = kinfo->si_code;
cc731525
EB
100 switch (siginfo_layout(kinfo->si_signo, kinfo->si_code)) {
101 case SIL_KILL:
5611f55e
EB
102 new.ssi_pid = kinfo->si_pid;
103 new.ssi_uid = kinfo->si_uid;
fba2afaa 104 break;
cc731525 105 case SIL_TIMER:
5611f55e
EB
106 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;
fba2afaa 110 break;
cc731525 111 case SIL_POLL:
5611f55e
EB
112 new.ssi_band = kinfo->si_band;
113 new.ssi_fd = kinfo->si_fd;
fba2afaa 114 break;
31931c93
EB
115 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 */
cc731525 124 case SIL_FAULT:
5611f55e 125 new.ssi_addr = (long) kinfo->si_addr;
fba2afaa 126#ifdef __ARCH_SI_TRAPNO
5611f55e 127 new.ssi_trapno = kinfo->si_trapno;
b8aeec34 128#endif
31931c93
EB
129 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;
fba2afaa 136 break;
cc731525 137 case SIL_CHLD:
5611f55e
EB
138 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;
fba2afaa 143 break;
cc731525 144 case SIL_RT:
0859ab59
DL
145 /*
146 * This case catches also the signals queued by sigqueue().
147 */
5611f55e
EB
148 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;
fba2afaa 152 break;
76b7f670
EB
153 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;
fba2afaa
DL
158 }
159
5611f55e
EB
160 if (copy_to_user(uinfo, &new, sizeof(struct signalfd_siginfo)))
161 return -EFAULT;
162
163 return sizeof(*uinfo);
fba2afaa
DL
164}
165
ae7795bc 166static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, kernel_siginfo_t *info,
b3762bfc
DA
167 int nonblock)
168{
169 ssize_t ret;
b3762bfc
DA
170 DECLARE_WAITQUEUE(wait, current);
171
b8fceee1
DL
172 spin_lock_irq(&current->sighand->siglock);
173 ret = dequeue_signal(current, &ctx->sigmask, info);
b3762bfc
DA
174 switch (ret) {
175 case 0:
176 if (!nonblock)
177 break;
178 ret = -EAGAIN;
0a4c9265 179 /* fall through */
b3762bfc 180 default:
b8fceee1 181 spin_unlock_irq(&current->sighand->siglock);
b3762bfc
DA
182 return ret;
183 }
184
b8fceee1 185 add_wait_queue(&current->sighand->signalfd_wqh, &wait);
b3762bfc
DA
186 for (;;) {
187 set_current_state(TASK_INTERRUPTIBLE);
b8fceee1 188 ret = dequeue_signal(current, &ctx->sigmask, info);
b3762bfc
DA
189 if (ret != 0)
190 break;
191 if (signal_pending(current)) {
192 ret = -ERESTARTSYS;
193 break;
194 }
b8fceee1 195 spin_unlock_irq(&current->sighand->siglock);
b3762bfc 196 schedule();
b8fceee1 197 spin_lock_irq(&current->sighand->siglock);
b3762bfc 198 }
b8fceee1 199 spin_unlock_irq(&current->sighand->siglock);
b3762bfc 200
b8fceee1 201 remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
b3762bfc
DA
202 __set_current_state(TASK_RUNNING);
203
204 return ret;
205}
206
fba2afaa 207/*
b8fceee1
DL
208 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
209 * error code. The "count" parameter must be at least the size of a
210 * "struct signalfd_siginfo".
fba2afaa
DL
211 */
212static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
213 loff_t *ppos)
214{
215 struct signalfd_ctx *ctx = file->private_data;
b3762bfc
DA
216 struct signalfd_siginfo __user *siginfo;
217 int nonblock = file->f_flags & O_NONBLOCK;
218 ssize_t ret, total = 0;
ae7795bc 219 kernel_siginfo_t info;
fba2afaa 220
b3762bfc
DA
221 count /= sizeof(struct signalfd_siginfo);
222 if (!count)
fba2afaa 223 return -EINVAL;
fba2afaa 224
b3762bfc 225 siginfo = (struct signalfd_siginfo __user *) buf;
b3762bfc
DA
226 do {
227 ret = signalfd_dequeue(ctx, &info, nonblock);
228 if (unlikely(ret <= 0))
229 break;
230 ret = signalfd_copyinfo(siginfo, &info);
231 if (ret < 0)
232 break;
233 siginfo++;
234 total += ret;
235 nonblock = 1;
236 } while (--count);
237
b8fceee1 238 return total ? total: ret;
fba2afaa
DL
239}
240
138d22b5 241#ifdef CONFIG_PROC_FS
a3816ab0 242static void signalfd_show_fdinfo(struct seq_file *m, struct file *f)
138d22b5
CG
243{
244 struct signalfd_ctx *ctx = f->private_data;
245 sigset_t sigmask;
246
247 sigmask = ctx->sigmask;
248 signotset(&sigmask);
249 render_sigset_t(m, "sigmask:\t", &sigmask);
138d22b5
CG
250}
251#endif
252
fba2afaa 253static const struct file_operations signalfd_fops = {
138d22b5
CG
254#ifdef CONFIG_PROC_FS
255 .show_fdinfo = signalfd_show_fdinfo,
256#endif
fba2afaa
DL
257 .release = signalfd_release,
258 .poll = signalfd_poll,
259 .read = signalfd_read,
6038f373 260 .llseek = noop_llseek,
fba2afaa
DL
261};
262
5ed0127f 263static int do_signalfd4(int ufd, sigset_t *mask, int flags)
fba2afaa 264{
fba2afaa 265 struct signalfd_ctx *ctx;
fba2afaa 266
e38b36f3
UD
267 /* Check the SFD_* constants for consistency. */
268 BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
269 BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
270
5fb5e049 271 if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
9deb27ba
UD
272 return -EINVAL;
273
5ed0127f
AV
274 sigdelsetmask(mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
275 signotset(mask);
fba2afaa
DL
276
277 if (ufd == -1) {
278 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
279 if (!ctx)
280 return -ENOMEM;
281
5ed0127f 282 ctx->sigmask = *mask;
fba2afaa
DL
283
284 /*
285 * When we call this, the initialization must be complete, since
286 * anon_inode_getfd() will install the fd.
287 */
7d9dbca3 288 ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
628ff7c1 289 O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
2030a42c
AV
290 if (ufd < 0)
291 kfree(ctx);
fba2afaa 292 } else {
2903ff01
AV
293 struct fd f = fdget(ufd);
294 if (!f.file)
fba2afaa 295 return -EBADF;
2903ff01
AV
296 ctx = f.file->private_data;
297 if (f.file->f_op != &signalfd_fops) {
298 fdput(f);
fba2afaa
DL
299 return -EINVAL;
300 }
b8fceee1 301 spin_lock_irq(&current->sighand->siglock);
5ed0127f 302 ctx->sigmask = *mask;
b8fceee1
DL
303 spin_unlock_irq(&current->sighand->siglock);
304
305 wake_up(&current->sighand->signalfd_wqh);
2903ff01 306 fdput(f);
fba2afaa
DL
307 }
308
309 return ufd;
fba2afaa 310}
9deb27ba 311
52fb6db0
DB
312SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
313 size_t, sizemask, int, flags)
314{
5ed0127f
AV
315 sigset_t mask;
316
317 if (sizemask != sizeof(sigset_t) ||
318 copy_from_user(&mask, user_mask, sizeof(mask)))
319 return -EINVAL;
320 return do_signalfd4(ufd, &mask, flags);
52fb6db0
DB
321}
322
836f92ad
HC
323SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
324 size_t, sizemask)
9deb27ba 325{
5ed0127f
AV
326 sigset_t mask;
327
328 if (sizemask != sizeof(sigset_t) ||
329 copy_from_user(&mask, user_mask, sizeof(mask)))
330 return -EINVAL;
331 return do_signalfd4(ufd, &mask, 0);
9deb27ba 332}
7d197ed4
AV
333
334#ifdef CONFIG_COMPAT
570484bf 335static long do_compat_signalfd4(int ufd,
5ed0127f 336 const compat_sigset_t __user *user_mask,
570484bf 337 compat_size_t sigsetsize, int flags)
7d197ed4 338{
5ed0127f 339 sigset_t mask;
7d197ed4
AV
340
341 if (sigsetsize != sizeof(compat_sigset_t))
342 return -EINVAL;
5ed0127f 343 if (get_compat_sigset(&mask, user_mask))
7d197ed4 344 return -EFAULT;
5ed0127f 345 return do_signalfd4(ufd, &mask, flags);
7d197ed4
AV
346}
347
570484bf 348COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd,
5ed0127f 349 const compat_sigset_t __user *, user_mask,
570484bf
DB
350 compat_size_t, sigsetsize,
351 int, flags)
352{
5ed0127f 353 return do_compat_signalfd4(ufd, user_mask, sigsetsize, flags);
570484bf
DB
354}
355
7d197ed4 356COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd,
5ed0127f 357 const compat_sigset_t __user *, user_mask,
7d197ed4
AV
358 compat_size_t, sigsetsize)
359{
5ed0127f 360 return do_compat_signalfd4(ufd, user_mask, sigsetsize, 0);
7d197ed4
AV
361}
362#endif