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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 |
36 | void 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 | 51 | struct signalfd_ctx { |
fba2afaa | 52 | sigset_t sigmask; |
fba2afaa DL |
53 | }; |
54 | ||
fba2afaa DL |
55 | static int signalfd_release(struct inode *inode, struct file *file) |
56 | { | |
b8fceee1 | 57 | kfree(file->private_data); |
fba2afaa DL |
58 | return 0; |
59 | } | |
60 | ||
076ccb76 | 61 | static __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, ¤t->sighand->signalfd_wqh, wait); |
fba2afaa | 67 | |
b8fceee1 DL |
68 | spin_lock_irq(¤t->sighand->siglock); |
69 | if (next_signal(¤t->pending, &ctx->sigmask) || | |
70 | next_signal(¤t->signal->shared_pending, | |
71 | &ctx->sigmask)) | |
a9a08845 | 72 | events |= EPOLLIN; |
b8fceee1 | 73 | spin_unlock_irq(¤t->sighand->siglock); |
fba2afaa DL |
74 | |
75 | return events; | |
76 | } | |
77 | ||
78 | /* | |
79 | * Copied from copy_siginfo_to_user() in kernel/signal.c | |
80 | */ | |
81 | static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo, | |
82 | siginfo_t const *kinfo) | |
83 | { | |
84 | long err; | |
85 | ||
86 | BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128); | |
87 | ||
88 | /* | |
14e4a0f2 | 89 | * Unused members should be zero ... |
fba2afaa DL |
90 | */ |
91 | err = __clear_user(uinfo, sizeof(*uinfo)); | |
92 | ||
93 | /* | |
94 | * If you change siginfo_t structure, please be sure | |
95 | * this code is fixed accordingly. | |
96 | */ | |
96358de6 DL |
97 | err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo); |
98 | err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno); | |
cc731525 EB |
99 | err |= __put_user(kinfo->si_code, &uinfo->ssi_code); |
100 | switch (siginfo_layout(kinfo->si_signo, kinfo->si_code)) { | |
101 | case SIL_KILL: | |
96358de6 DL |
102 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
103 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); | |
fba2afaa | 104 | break; |
cc731525 | 105 | case SIL_TIMER: |
96358de6 DL |
106 | err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid); |
107 | err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun); | |
108 | err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr); | |
a2a20c41 | 109 | err |= __put_user(kinfo->si_int, &uinfo->ssi_int); |
fba2afaa | 110 | break; |
cc731525 | 111 | case SIL_POLL: |
96358de6 DL |
112 | err |= __put_user(kinfo->si_band, &uinfo->ssi_band); |
113 | err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd); | |
fba2afaa | 114 | break; |
cc731525 | 115 | case SIL_FAULT: |
96358de6 | 116 | err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr); |
fba2afaa | 117 | #ifdef __ARCH_SI_TRAPNO |
96358de6 | 118 | err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno); |
b8aeec34 HS |
119 | #endif |
120 | #ifdef BUS_MCEERR_AO | |
9026e820 | 121 | /* |
b8aeec34 HS |
122 | * Other callers might not initialize the si_lsb field, |
123 | * so check explicitly for the right codes here. | |
124 | */ | |
3ead7c52 | 125 | if (kinfo->si_signo == SIGBUS && |
9026e820 RD |
126 | kinfo->si_code == BUS_MCEERR_AO) |
127 | err |= __put_user((short) kinfo->si_addr_lsb, | |
128 | &uinfo->ssi_addr_lsb); | |
129 | #endif | |
130 | #ifdef BUS_MCEERR_AR | |
131 | /* | |
132 | * Other callers might not initialize the si_lsb field, | |
133 | * so check explicitly for the right codes here. | |
134 | */ | |
135 | if (kinfo->si_signo == SIGBUS && | |
136 | kinfo->si_code == BUS_MCEERR_AR) | |
b8aeec34 HS |
137 | err |= __put_user((short) kinfo->si_addr_lsb, |
138 | &uinfo->ssi_addr_lsb); | |
fba2afaa DL |
139 | #endif |
140 | break; | |
cc731525 | 141 | case SIL_CHLD: |
96358de6 DL |
142 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
143 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); | |
144 | err |= __put_user(kinfo->si_status, &uinfo->ssi_status); | |
145 | err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime); | |
146 | err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime); | |
fba2afaa | 147 | break; |
cc731525 | 148 | case SIL_RT: |
0859ab59 DL |
149 | default: |
150 | /* | |
151 | * This case catches also the signals queued by sigqueue(). | |
152 | */ | |
96358de6 DL |
153 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
154 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); | |
0859ab59 DL |
155 | err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr); |
156 | err |= __put_user(kinfo->si_int, &uinfo->ssi_int); | |
fba2afaa DL |
157 | break; |
158 | } | |
159 | ||
160 | return err ? -EFAULT: sizeof(*uinfo); | |
161 | } | |
162 | ||
b3762bfc DA |
163 | static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info, |
164 | int nonblock) | |
165 | { | |
166 | ssize_t ret; | |
b3762bfc DA |
167 | DECLARE_WAITQUEUE(wait, current); |
168 | ||
b8fceee1 DL |
169 | spin_lock_irq(¤t->sighand->siglock); |
170 | ret = dequeue_signal(current, &ctx->sigmask, info); | |
b3762bfc DA |
171 | switch (ret) { |
172 | case 0: | |
173 | if (!nonblock) | |
174 | break; | |
175 | ret = -EAGAIN; | |
176 | default: | |
b8fceee1 | 177 | spin_unlock_irq(¤t->sighand->siglock); |
b3762bfc DA |
178 | return ret; |
179 | } | |
180 | ||
b8fceee1 | 181 | add_wait_queue(¤t->sighand->signalfd_wqh, &wait); |
b3762bfc DA |
182 | for (;;) { |
183 | set_current_state(TASK_INTERRUPTIBLE); | |
b8fceee1 | 184 | ret = dequeue_signal(current, &ctx->sigmask, info); |
b3762bfc DA |
185 | if (ret != 0) |
186 | break; | |
187 | if (signal_pending(current)) { | |
188 | ret = -ERESTARTSYS; | |
189 | break; | |
190 | } | |
b8fceee1 | 191 | spin_unlock_irq(¤t->sighand->siglock); |
b3762bfc | 192 | schedule(); |
b8fceee1 | 193 | spin_lock_irq(¤t->sighand->siglock); |
b3762bfc | 194 | } |
b8fceee1 | 195 | spin_unlock_irq(¤t->sighand->siglock); |
b3762bfc | 196 | |
b8fceee1 | 197 | remove_wait_queue(¤t->sighand->signalfd_wqh, &wait); |
b3762bfc DA |
198 | __set_current_state(TASK_RUNNING); |
199 | ||
200 | return ret; | |
201 | } | |
202 | ||
fba2afaa | 203 | /* |
b8fceee1 DL |
204 | * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative |
205 | * error code. The "count" parameter must be at least the size of a | |
206 | * "struct signalfd_siginfo". | |
fba2afaa DL |
207 | */ |
208 | static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count, | |
209 | loff_t *ppos) | |
210 | { | |
211 | struct signalfd_ctx *ctx = file->private_data; | |
b3762bfc DA |
212 | struct signalfd_siginfo __user *siginfo; |
213 | int nonblock = file->f_flags & O_NONBLOCK; | |
214 | ssize_t ret, total = 0; | |
fba2afaa | 215 | siginfo_t info; |
fba2afaa | 216 | |
b3762bfc DA |
217 | count /= sizeof(struct signalfd_siginfo); |
218 | if (!count) | |
fba2afaa | 219 | return -EINVAL; |
fba2afaa | 220 | |
b3762bfc | 221 | siginfo = (struct signalfd_siginfo __user *) buf; |
b3762bfc DA |
222 | do { |
223 | ret = signalfd_dequeue(ctx, &info, nonblock); | |
224 | if (unlikely(ret <= 0)) | |
225 | break; | |
226 | ret = signalfd_copyinfo(siginfo, &info); | |
227 | if (ret < 0) | |
228 | break; | |
229 | siginfo++; | |
230 | total += ret; | |
231 | nonblock = 1; | |
232 | } while (--count); | |
233 | ||
b8fceee1 | 234 | return total ? total: ret; |
fba2afaa DL |
235 | } |
236 | ||
138d22b5 | 237 | #ifdef CONFIG_PROC_FS |
a3816ab0 | 238 | static void signalfd_show_fdinfo(struct seq_file *m, struct file *f) |
138d22b5 CG |
239 | { |
240 | struct signalfd_ctx *ctx = f->private_data; | |
241 | sigset_t sigmask; | |
242 | ||
243 | sigmask = ctx->sigmask; | |
244 | signotset(&sigmask); | |
245 | render_sigset_t(m, "sigmask:\t", &sigmask); | |
138d22b5 CG |
246 | } |
247 | #endif | |
248 | ||
fba2afaa | 249 | static const struct file_operations signalfd_fops = { |
138d22b5 CG |
250 | #ifdef CONFIG_PROC_FS |
251 | .show_fdinfo = signalfd_show_fdinfo, | |
252 | #endif | |
fba2afaa DL |
253 | .release = signalfd_release, |
254 | .poll = signalfd_poll, | |
255 | .read = signalfd_read, | |
6038f373 | 256 | .llseek = noop_llseek, |
fba2afaa DL |
257 | }; |
258 | ||
52fb6db0 DB |
259 | static int do_signalfd4(int ufd, sigset_t __user *user_mask, size_t sizemask, |
260 | int flags) | |
fba2afaa | 261 | { |
fba2afaa DL |
262 | sigset_t sigmask; |
263 | struct signalfd_ctx *ctx; | |
fba2afaa | 264 | |
e38b36f3 UD |
265 | /* Check the SFD_* constants for consistency. */ |
266 | BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC); | |
267 | BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK); | |
268 | ||
5fb5e049 | 269 | if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK)) |
9deb27ba UD |
270 | return -EINVAL; |
271 | ||
fba2afaa DL |
272 | if (sizemask != sizeof(sigset_t) || |
273 | copy_from_user(&sigmask, user_mask, sizeof(sigmask))) | |
f50cadaa | 274 | return -EINVAL; |
fba2afaa DL |
275 | sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP)); |
276 | signotset(&sigmask); | |
277 | ||
278 | if (ufd == -1) { | |
279 | ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); | |
280 | if (!ctx) | |
281 | return -ENOMEM; | |
282 | ||
fba2afaa | 283 | ctx->sigmask = sigmask; |
fba2afaa DL |
284 | |
285 | /* | |
286 | * When we call this, the initialization must be complete, since | |
287 | * anon_inode_getfd() will install the fd. | |
288 | */ | |
7d9dbca3 | 289 | ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx, |
628ff7c1 | 290 | O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK))); |
2030a42c AV |
291 | if (ufd < 0) |
292 | kfree(ctx); | |
fba2afaa | 293 | } else { |
2903ff01 AV |
294 | struct fd f = fdget(ufd); |
295 | if (!f.file) | |
fba2afaa | 296 | return -EBADF; |
2903ff01 AV |
297 | ctx = f.file->private_data; |
298 | if (f.file->f_op != &signalfd_fops) { | |
299 | fdput(f); | |
fba2afaa DL |
300 | return -EINVAL; |
301 | } | |
b8fceee1 DL |
302 | spin_lock_irq(¤t->sighand->siglock); |
303 | ctx->sigmask = sigmask; | |
304 | spin_unlock_irq(¤t->sighand->siglock); | |
305 | ||
306 | wake_up(¤t->sighand->signalfd_wqh); | |
2903ff01 | 307 | fdput(f); |
fba2afaa DL |
308 | } |
309 | ||
310 | return ufd; | |
fba2afaa | 311 | } |
9deb27ba | 312 | |
52fb6db0 DB |
313 | SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask, |
314 | size_t, sizemask, int, flags) | |
315 | { | |
316 | return do_signalfd4(ufd, user_mask, sizemask, flags); | |
317 | } | |
318 | ||
836f92ad HC |
319 | SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask, |
320 | size_t, sizemask) | |
9deb27ba | 321 | { |
52fb6db0 | 322 | return do_signalfd4(ufd, user_mask, sizemask, 0); |
9deb27ba | 323 | } |
7d197ed4 AV |
324 | |
325 | #ifdef CONFIG_COMPAT | |
570484bf DB |
326 | static long do_compat_signalfd4(int ufd, |
327 | const compat_sigset_t __user *sigmask, | |
328 | compat_size_t sigsetsize, int flags) | |
7d197ed4 | 329 | { |
7d197ed4 AV |
330 | sigset_t tmp; |
331 | sigset_t __user *ksigmask; | |
332 | ||
333 | if (sigsetsize != sizeof(compat_sigset_t)) | |
334 | return -EINVAL; | |
3968cf62 | 335 | if (get_compat_sigset(&tmp, sigmask)) |
7d197ed4 | 336 | return -EFAULT; |
7d197ed4 AV |
337 | ksigmask = compat_alloc_user_space(sizeof(sigset_t)); |
338 | if (copy_to_user(ksigmask, &tmp, sizeof(sigset_t))) | |
339 | return -EFAULT; | |
340 | ||
52fb6db0 | 341 | return do_signalfd4(ufd, ksigmask, sizeof(sigset_t), flags); |
7d197ed4 AV |
342 | } |
343 | ||
570484bf DB |
344 | COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd, |
345 | const compat_sigset_t __user *, sigmask, | |
346 | compat_size_t, sigsetsize, | |
347 | int, flags) | |
348 | { | |
349 | return do_compat_signalfd4(ufd, sigmask, sigsetsize, flags); | |
350 | } | |
351 | ||
7d197ed4 AV |
352 | COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd, |
353 | const compat_sigset_t __user *,sigmask, | |
354 | compat_size_t, sigsetsize) | |
355 | { | |
570484bf | 356 | return do_compat_signalfd4(ufd, sigmask, sigsetsize, 0); |
7d197ed4 AV |
357 | } |
358 | #endif |