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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{
9537bae0 38 wake_up_pollfree(&sighand->signalfd_wqh);
d80e731e
ON
39}
40
fba2afaa 41struct signalfd_ctx {
fba2afaa 42 sigset_t sigmask;
fba2afaa
DL
43};
44
fba2afaa
DL
45static int signalfd_release(struct inode *inode, struct file *file)
46{
b8fceee1 47 kfree(file->private_data);
fba2afaa
DL
48 return 0;
49}
50
076ccb76 51static __poll_t signalfd_poll(struct file *file, poll_table *wait)
fba2afaa
DL
52{
53 struct signalfd_ctx *ctx = file->private_data;
076ccb76 54 __poll_t events = 0;
fba2afaa 55
b8fceee1 56 poll_wait(file, &current->sighand->signalfd_wqh, wait);
fba2afaa 57
b8fceee1
DL
58 spin_lock_irq(&current->sighand->siglock);
59 if (next_signal(&current->pending, &ctx->sigmask) ||
60 next_signal(&current->signal->shared_pending,
61 &ctx->sigmask))
a9a08845 62 events |= EPOLLIN;
b8fceee1 63 spin_unlock_irq(&current->sighand->siglock);
fba2afaa
DL
64
65 return events;
66}
67
68/*
69 * Copied from copy_siginfo_to_user() in kernel/signal.c
70 */
fbe38120 71static int signalfd_copyinfo(struct iov_iter *to, kernel_siginfo_t const *kinfo)
fba2afaa 72{
5611f55e 73 struct signalfd_siginfo new;
fba2afaa
DL
74
75 BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
76
77 /*
14e4a0f2 78 * Unused members should be zero ...
fba2afaa 79 */
5611f55e 80 memset(&new, 0, sizeof(new));
fba2afaa
DL
81
82 /*
83 * If you change siginfo_t structure, please be sure
84 * this code is fixed accordingly.
85 */
5611f55e
EB
86 new.ssi_signo = kinfo->si_signo;
87 new.ssi_errno = kinfo->si_errno;
88 new.ssi_code = kinfo->si_code;
cc731525
EB
89 switch (siginfo_layout(kinfo->si_signo, kinfo->si_code)) {
90 case SIL_KILL:
5611f55e
EB
91 new.ssi_pid = kinfo->si_pid;
92 new.ssi_uid = kinfo->si_uid;
fba2afaa 93 break;
cc731525 94 case SIL_TIMER:
5611f55e
EB
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;
fba2afaa 99 break;
cc731525 100 case SIL_POLL:
5611f55e
EB
101 new.ssi_band = kinfo->si_band;
102 new.ssi_fd = kinfo->si_fd;
fba2afaa 103 break;
31931c93
EB
104 case SIL_FAULT_BNDERR:
105 case SIL_FAULT_PKUERR:
f4ac7302 106 case SIL_FAULT_PERF_EVENT:
31931c93 107 /*
922e3013 108 * Fall through to the SIL_FAULT case. SIL_FAULT_BNDERR,
f4ac7302 109 * SIL_FAULT_PKUERR, and SIL_FAULT_PERF_EVENT are only
922e3013
EB
110 * generated by faults that deliver them synchronously to
111 * userspace. In case someone injects one of these signals
112 * and signalfd catches it treat it as SIL_FAULT.
31931c93 113 */
cc731525 114 case SIL_FAULT:
5611f55e 115 new.ssi_addr = (long) kinfo->si_addr;
9abcabe3
EB
116 break;
117 case SIL_FAULT_TRAPNO:
118 new.ssi_addr = (long) kinfo->si_addr;
5611f55e 119 new.ssi_trapno = kinfo->si_trapno;
31931c93
EB
120 break;
121 case SIL_FAULT_MCEERR:
122 new.ssi_addr = (long) kinfo->si_addr;
31931c93 123 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
fba2afaa 124 break;
cc731525 125 case SIL_CHLD:
5611f55e
EB
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;
fba2afaa 131 break;
cc731525 132 case SIL_RT:
0859ab59
DL
133 /*
134 * This case catches also the signals queued by sigqueue().
135 */
5611f55e
EB
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;
fba2afaa 140 break;
76b7f670
EB
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;
fba2afaa
DL
146 }
147
fbe38120 148 if (!copy_to_iter_full(&new, sizeof(struct signalfd_siginfo), to))
5611f55e
EB
149 return -EFAULT;
150
fbe38120 151 return sizeof(struct signalfd_siginfo);
fba2afaa
DL
152}
153
ae7795bc 154static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, kernel_siginfo_t *info,
b3762bfc
DA
155 int nonblock)
156{
5768d890 157 enum pid_type type;
b3762bfc 158 ssize_t ret;
b3762bfc
DA
159 DECLARE_WAITQUEUE(wait, current);
160
b8fceee1 161 spin_lock_irq(&current->sighand->siglock);
a2b80ce8 162 ret = dequeue_signal(&ctx->sigmask, info, &type);
b3762bfc
DA
163 switch (ret) {
164 case 0:
165 if (!nonblock)
166 break;
167 ret = -EAGAIN;
df561f66 168 fallthrough;
b3762bfc 169 default:
b8fceee1 170 spin_unlock_irq(&current->sighand->siglock);
b3762bfc
DA
171 return ret;
172 }
173
b8fceee1 174 add_wait_queue(&current->sighand->signalfd_wqh, &wait);
b3762bfc
DA
175 for (;;) {
176 set_current_state(TASK_INTERRUPTIBLE);
a2b80ce8 177 ret = dequeue_signal(&ctx->sigmask, info, &type);
b3762bfc
DA
178 if (ret != 0)
179 break;
180 if (signal_pending(current)) {
181 ret = -ERESTARTSYS;
182 break;
183 }
b8fceee1 184 spin_unlock_irq(&current->sighand->siglock);
b3762bfc 185 schedule();
b8fceee1 186 spin_lock_irq(&current->sighand->siglock);
b3762bfc 187 }
b8fceee1 188 spin_unlock_irq(&current->sighand->siglock);
b3762bfc 189
b8fceee1 190 remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
b3762bfc
DA
191 __set_current_state(TASK_RUNNING);
192
193 return ret;
194}
195
fba2afaa 196/*
b8fceee1
DL
197 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
198 * error code. The "count" parameter must be at least the size of a
199 * "struct signalfd_siginfo".
fba2afaa 200 */
fbe38120 201static ssize_t signalfd_read_iter(struct kiocb *iocb, struct iov_iter *to)
fba2afaa 202{
fbe38120 203 struct file *file = iocb->ki_filp;
fba2afaa 204 struct signalfd_ctx *ctx = file->private_data;
fbe38120 205 size_t count = iov_iter_count(to);
b3762bfc 206 ssize_t ret, total = 0;
ae7795bc 207 kernel_siginfo_t info;
fbe38120 208 bool nonblock;
fba2afaa 209
b3762bfc
DA
210 count /= sizeof(struct signalfd_siginfo);
211 if (!count)
fba2afaa 212 return -EINVAL;
fba2afaa 213
fbe38120 214 nonblock = file->f_flags & O_NONBLOCK || iocb->ki_flags & IOCB_NOWAIT;
b3762bfc
DA
215 do {
216 ret = signalfd_dequeue(ctx, &info, nonblock);
217 if (unlikely(ret <= 0))
218 break;
fbe38120 219 ret = signalfd_copyinfo(to, &info);
b3762bfc
DA
220 if (ret < 0)
221 break;
b3762bfc
DA
222 total += ret;
223 nonblock = 1;
224 } while (--count);
225
b8fceee1 226 return total ? total: ret;
fba2afaa
DL
227}
228
138d22b5 229#ifdef CONFIG_PROC_FS
a3816ab0 230static void signalfd_show_fdinfo(struct seq_file *m, struct file *f)
138d22b5
CG
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);
138d22b5
CG
238}
239#endif
240
fba2afaa 241static const struct file_operations signalfd_fops = {
138d22b5
CG
242#ifdef CONFIG_PROC_FS
243 .show_fdinfo = signalfd_show_fdinfo,
244#endif
fba2afaa
DL
245 .release = signalfd_release,
246 .poll = signalfd_poll,
fbe38120 247 .read_iter = signalfd_read_iter,
6038f373 248 .llseek = noop_llseek,
fba2afaa
DL
249};
250
5ed0127f 251static int do_signalfd4(int ufd, sigset_t *mask, int flags)
fba2afaa 252{
fba2afaa 253 struct signalfd_ctx *ctx;
fba2afaa 254
e38b36f3
UD
255 /* Check the SFD_* constants for consistency. */
256 BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
257 BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
258
5fb5e049 259 if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
9deb27ba
UD
260 return -EINVAL;
261
5ed0127f
AV
262 sigdelsetmask(mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
263 signotset(mask);
fba2afaa
DL
264
265 if (ufd == -1) {
fbe38120
JA
266 struct file *file;
267
fba2afaa
DL
268 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
269 if (!ctx)
270 return -ENOMEM;
271
5ed0127f 272 ctx->sigmask = *mask;
fba2afaa 273
fbe38120
JA
274 ufd = get_unused_fd_flags(flags & O_CLOEXEC);
275 if (ufd < 0) {
276 kfree(ctx);
277 return ufd;
278 }
279
f9835fa1
AV
280 file = anon_inode_getfile_fmode("[signalfd]", &signalfd_fops,
281 ctx, O_RDWR | (flags & O_NONBLOCK),
282 FMODE_NOWAIT);
fbe38120
JA
283 if (IS_ERR(file)) {
284 put_unused_fd(ufd);
285 kfree(ctx);
f826bc9d 286 return PTR_ERR(file);
fbe38120 287 }
fbe38120 288 fd_install(ufd, file);
fba2afaa 289 } else {
6348be02
AV
290 CLASS(fd, f)(ufd);
291 if (fd_empty(f))
fba2afaa 292 return -EBADF;
1da91ea8 293 ctx = fd_file(f)->private_data;
6348be02 294 if (fd_file(f)->f_op != &signalfd_fops)
fba2afaa 295 return -EINVAL;
b8fceee1 296 spin_lock_irq(&current->sighand->siglock);
5ed0127f 297 ctx->sigmask = *mask;
b8fceee1
DL
298 spin_unlock_irq(&current->sighand->siglock);
299
300 wake_up(&current->sighand->signalfd_wqh);
fba2afaa
DL
301 }
302
303 return ufd;
fba2afaa 304}
9deb27ba 305
52fb6db0
DB
306SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
307 size_t, sizemask, int, flags)
308{
5ed0127f
AV
309 sigset_t mask;
310
a089e3fd 311 if (sizemask != sizeof(sigset_t))
5ed0127f 312 return -EINVAL;
a089e3fd
HD
313 if (copy_from_user(&mask, user_mask, sizeof(mask)))
314 return -EFAULT;
5ed0127f 315 return do_signalfd4(ufd, &mask, flags);
52fb6db0
DB
316}
317
836f92ad
HC
318SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
319 size_t, sizemask)
9deb27ba 320{
5ed0127f
AV
321 sigset_t mask;
322
a089e3fd 323 if (sizemask != sizeof(sigset_t))
5ed0127f 324 return -EINVAL;
a089e3fd
HD
325 if (copy_from_user(&mask, user_mask, sizeof(mask)))
326 return -EFAULT;
5ed0127f 327 return do_signalfd4(ufd, &mask, 0);
9deb27ba 328}
7d197ed4
AV
329
330#ifdef CONFIG_COMPAT
570484bf 331static long do_compat_signalfd4(int ufd,
5ed0127f 332 const compat_sigset_t __user *user_mask,
570484bf 333 compat_size_t sigsetsize, int flags)
7d197ed4 334{
5ed0127f 335 sigset_t mask;
7d197ed4
AV
336
337 if (sigsetsize != sizeof(compat_sigset_t))
338 return -EINVAL;
5ed0127f 339 if (get_compat_sigset(&mask, user_mask))
7d197ed4 340 return -EFAULT;
5ed0127f 341 return do_signalfd4(ufd, &mask, flags);
7d197ed4
AV
342}
343
570484bf 344COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd,
5ed0127f 345 const compat_sigset_t __user *, user_mask,
570484bf
DB
346 compat_size_t, sigsetsize,
347 int, flags)
348{
5ed0127f 349 return do_compat_signalfd4(ufd, user_mask, sigsetsize, flags);
570484bf
DB
350}
351
7d197ed4 352COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd,
5ed0127f 353 const compat_sigset_t __user *, user_mask,
7d197ed4
AV
354 compat_size_t, sigsetsize)
355{
5ed0127f 356 return do_compat_signalfd4(ufd, user_mask, sigsetsize, 0);
7d197ed4
AV
357}
358#endif