1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 2003 Linus Torvalds
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() call
17 * Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
18 * Attach to the sighand only during read() and poll().
21 #include <linux/file.h>
22 #include <linux/poll.h>
23 #include <linux/init.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>
36 void signalfd_cleanup(struct sighand_struct
*sighand
)
38 wake_up_pollfree(&sighand
->signalfd_wqh
);
45 static int signalfd_release(struct inode
*inode
, struct file
*file
)
47 kfree(file
->private_data
);
51 static __poll_t
signalfd_poll(struct file
*file
, poll_table
*wait
)
53 struct signalfd_ctx
*ctx
= file
->private_data
;
56 poll_wait(file
, ¤t
->sighand
->signalfd_wqh
, wait
);
58 spin_lock_irq(¤t
->sighand
->siglock
);
59 if (next_signal(¤t
->pending
, &ctx
->sigmask
) ||
60 next_signal(¤t
->signal
->shared_pending
,
63 spin_unlock_irq(¤t
->sighand
->siglock
);
69 * Copied from copy_siginfo_to_user() in kernel/signal.c
71 static int signalfd_copyinfo(struct signalfd_siginfo __user
*uinfo
,
72 kernel_siginfo_t
const *kinfo
)
74 struct signalfd_siginfo
new;
76 BUILD_BUG_ON(sizeof(struct signalfd_siginfo
) != 128);
79 * Unused members should be zero ...
81 memset(&new, 0, sizeof(new));
84 * If you change siginfo_t structure, please be sure
85 * this code is fixed accordingly.
87 new.ssi_signo
= kinfo
->si_signo
;
88 new.ssi_errno
= kinfo
->si_errno
;
89 new.ssi_code
= kinfo
->si_code
;
90 switch (siginfo_layout(kinfo
->si_signo
, kinfo
->si_code
)) {
92 new.ssi_pid
= kinfo
->si_pid
;
93 new.ssi_uid
= kinfo
->si_uid
;
96 new.ssi_tid
= kinfo
->si_tid
;
97 new.ssi_overrun
= kinfo
->si_overrun
;
98 new.ssi_ptr
= (long) kinfo
->si_ptr
;
99 new.ssi_int
= kinfo
->si_int
;
102 new.ssi_band
= kinfo
->si_band
;
103 new.ssi_fd
= kinfo
->si_fd
;
105 case SIL_FAULT_BNDERR
:
106 case SIL_FAULT_PKUERR
:
107 case SIL_FAULT_PERF_EVENT
:
109 * Fall through to the SIL_FAULT case. SIL_FAULT_BNDERR,
110 * SIL_FAULT_PKUERR, and SIL_FAULT_PERF_EVENT are only
111 * generated by faults that deliver them synchronously to
112 * userspace. In case someone injects one of these signals
113 * and signalfd catches it treat it as SIL_FAULT.
116 new.ssi_addr
= (long) kinfo
->si_addr
;
118 case SIL_FAULT_TRAPNO
:
119 new.ssi_addr
= (long) kinfo
->si_addr
;
120 new.ssi_trapno
= kinfo
->si_trapno
;
122 case SIL_FAULT_MCEERR
:
123 new.ssi_addr
= (long) kinfo
->si_addr
;
124 new.ssi_addr_lsb
= (short) kinfo
->si_addr_lsb
;
127 new.ssi_pid
= kinfo
->si_pid
;
128 new.ssi_uid
= kinfo
->si_uid
;
129 new.ssi_status
= kinfo
->si_status
;
130 new.ssi_utime
= kinfo
->si_utime
;
131 new.ssi_stime
= kinfo
->si_stime
;
135 * This case catches also the signals queued by sigqueue().
137 new.ssi_pid
= kinfo
->si_pid
;
138 new.ssi_uid
= kinfo
->si_uid
;
139 new.ssi_ptr
= (long) kinfo
->si_ptr
;
140 new.ssi_int
= kinfo
->si_int
;
143 new.ssi_call_addr
= (long) kinfo
->si_call_addr
;
144 new.ssi_syscall
= kinfo
->si_syscall
;
145 new.ssi_arch
= kinfo
->si_arch
;
149 if (copy_to_user(uinfo
, &new, sizeof(struct signalfd_siginfo
)))
152 return sizeof(*uinfo
);
155 static ssize_t
signalfd_dequeue(struct signalfd_ctx
*ctx
, kernel_siginfo_t
*info
,
160 DECLARE_WAITQUEUE(wait
, current
);
162 spin_lock_irq(¤t
->sighand
->siglock
);
163 ret
= dequeue_signal(current
, &ctx
->sigmask
, info
, &type
);
171 spin_unlock_irq(¤t
->sighand
->siglock
);
175 add_wait_queue(¤t
->sighand
->signalfd_wqh
, &wait
);
177 set_current_state(TASK_INTERRUPTIBLE
);
178 ret
= dequeue_signal(current
, &ctx
->sigmask
, info
, &type
);
181 if (signal_pending(current
)) {
185 spin_unlock_irq(¤t
->sighand
->siglock
);
187 spin_lock_irq(¤t
->sighand
->siglock
);
189 spin_unlock_irq(¤t
->sighand
->siglock
);
191 remove_wait_queue(¤t
->sighand
->signalfd_wqh
, &wait
);
192 __set_current_state(TASK_RUNNING
);
198 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
199 * error code. The "count" parameter must be at least the size of a
200 * "struct signalfd_siginfo".
202 static ssize_t
signalfd_read(struct file
*file
, char __user
*buf
, size_t count
,
205 struct signalfd_ctx
*ctx
= file
->private_data
;
206 struct signalfd_siginfo __user
*siginfo
;
207 int nonblock
= file
->f_flags
& O_NONBLOCK
;
208 ssize_t ret
, total
= 0;
209 kernel_siginfo_t info
;
211 count
/= sizeof(struct signalfd_siginfo
);
215 siginfo
= (struct signalfd_siginfo __user
*) buf
;
217 ret
= signalfd_dequeue(ctx
, &info
, nonblock
);
218 if (unlikely(ret
<= 0))
220 ret
= signalfd_copyinfo(siginfo
, &info
);
228 return total
? total
: ret
;
231 #ifdef CONFIG_PROC_FS
232 static void signalfd_show_fdinfo(struct seq_file
*m
, struct file
*f
)
234 struct signalfd_ctx
*ctx
= f
->private_data
;
237 sigmask
= ctx
->sigmask
;
239 render_sigset_t(m
, "sigmask:\t", &sigmask
);
243 static const struct file_operations signalfd_fops
= {
244 #ifdef CONFIG_PROC_FS
245 .show_fdinfo
= signalfd_show_fdinfo
,
247 .release
= signalfd_release
,
248 .poll
= signalfd_poll
,
249 .read
= signalfd_read
,
250 .llseek
= noop_llseek
,
253 static int do_signalfd4(int ufd
, sigset_t
*mask
, int flags
)
255 struct signalfd_ctx
*ctx
;
257 /* Check the SFD_* constants for consistency. */
258 BUILD_BUG_ON(SFD_CLOEXEC
!= O_CLOEXEC
);
259 BUILD_BUG_ON(SFD_NONBLOCK
!= O_NONBLOCK
);
261 if (flags
& ~(SFD_CLOEXEC
| SFD_NONBLOCK
))
264 sigdelsetmask(mask
, sigmask(SIGKILL
) | sigmask(SIGSTOP
));
268 ctx
= kmalloc(sizeof(*ctx
), GFP_KERNEL
);
272 ctx
->sigmask
= *mask
;
275 * When we call this, the initialization must be complete, since
276 * anon_inode_getfd() will install the fd.
278 ufd
= anon_inode_getfd("[signalfd]", &signalfd_fops
, ctx
,
279 O_RDWR
| (flags
& (O_CLOEXEC
| O_NONBLOCK
)));
283 struct fd f
= fdget(ufd
);
286 ctx
= f
.file
->private_data
;
287 if (f
.file
->f_op
!= &signalfd_fops
) {
291 spin_lock_irq(¤t
->sighand
->siglock
);
292 ctx
->sigmask
= *mask
;
293 spin_unlock_irq(¤t
->sighand
->siglock
);
295 wake_up(¤t
->sighand
->signalfd_wqh
);
302 SYSCALL_DEFINE4(signalfd4
, int, ufd
, sigset_t __user
*, user_mask
,
303 size_t, sizemask
, int, flags
)
307 if (sizemask
!= sizeof(sigset_t
))
309 if (copy_from_user(&mask
, user_mask
, sizeof(mask
)))
311 return do_signalfd4(ufd
, &mask
, flags
);
314 SYSCALL_DEFINE3(signalfd
, int, ufd
, sigset_t __user
*, user_mask
,
319 if (sizemask
!= sizeof(sigset_t
))
321 if (copy_from_user(&mask
, user_mask
, sizeof(mask
)))
323 return do_signalfd4(ufd
, &mask
, 0);
327 static long do_compat_signalfd4(int ufd
,
328 const compat_sigset_t __user
*user_mask
,
329 compat_size_t sigsetsize
, int flags
)
333 if (sigsetsize
!= sizeof(compat_sigset_t
))
335 if (get_compat_sigset(&mask
, user_mask
))
337 return do_signalfd4(ufd
, &mask
, flags
);
340 COMPAT_SYSCALL_DEFINE4(signalfd4
, int, ufd
,
341 const compat_sigset_t __user
*, user_mask
,
342 compat_size_t
, sigsetsize
,
345 return do_compat_signalfd4(ufd
, user_mask
, sigsetsize
, flags
);
348 COMPAT_SYSCALL_DEFINE3(signalfd
, int, ufd
,
349 const compat_sigset_t __user
*, user_mask
,
350 compat_size_t
, sigsetsize
)
352 return do_compat_signalfd4(ufd
, user_mask
, sigsetsize
, 0);