blob: 619725644c75e4b30d5ba379f9d40a391466efdb [file] [log] [blame]
Davide Libenzifba2afa2007-05-10 22:23:13 -07001/*
2 * fs/signalfd.c
3 *
4 * Copyright (C) 2003 Linus Torvalds
5 *
6 * Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org>
7 * Changed ->read() to return a siginfo strcture instead of signal number.
8 * Fixed locking in ->poll().
9 * Added sighand-detach notification.
10 * Added fd re-use in sys_signalfd() syscall.
11 * Now using anonymous inode source.
12 * Thanks to Oleg Nesterov for useful code review and suggestions.
13 * More comments and suggestions from Arnd Bergmann.
Davide Libenzib8fceee2007-09-20 12:40:16 -070014 * Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
Davi Arnautb3762bf2007-05-23 13:58:04 -070015 * Retrieve multiple signals with one read() call
Davide Libenzib8fceee2007-09-20 12:40:16 -070016 * Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
17 * Attach to the sighand only during read() and poll().
Davide Libenzifba2afa2007-05-10 22:23:13 -070018 */
19
20#include <linux/file.h>
21#include <linux/poll.h>
22#include <linux/init.h>
23#include <linux/fs.h>
24#include <linux/sched.h>
25#include <linux/kernel.h>
26#include <linux/signal.h>
27#include <linux/list.h>
28#include <linux/anon_inodes.h>
29#include <linux/signalfd.h>
Adrian Bunk7ec37df2008-02-06 01:36:48 -080030#include <linux/syscalls.h>
Davide Libenzifba2afa2007-05-10 22:23:13 -070031
32struct signalfd_ctx {
Davide Libenzifba2afa2007-05-10 22:23:13 -070033 sigset_t sigmask;
Davide Libenzifba2afa2007-05-10 22:23:13 -070034};
35
Davide Libenzifba2afa2007-05-10 22:23:13 -070036static int signalfd_release(struct inode *inode, struct file *file)
37{
Davide Libenzib8fceee2007-09-20 12:40:16 -070038 kfree(file->private_data);
Davide Libenzifba2afa2007-05-10 22:23:13 -070039 return 0;
40}
41
42static unsigned int signalfd_poll(struct file *file, poll_table *wait)
43{
44 struct signalfd_ctx *ctx = file->private_data;
45 unsigned int events = 0;
Davide Libenzifba2afa2007-05-10 22:23:13 -070046
Davide Libenzib8fceee2007-09-20 12:40:16 -070047 poll_wait(file, &current->sighand->signalfd_wqh, wait);
Davide Libenzifba2afa2007-05-10 22:23:13 -070048
Davide Libenzib8fceee2007-09-20 12:40:16 -070049 spin_lock_irq(&current->sighand->siglock);
50 if (next_signal(&current->pending, &ctx->sigmask) ||
51 next_signal(&current->signal->shared_pending,
52 &ctx->sigmask))
Davide Libenzifba2afa2007-05-10 22:23:13 -070053 events |= POLLIN;
Davide Libenzib8fceee2007-09-20 12:40:16 -070054 spin_unlock_irq(&current->sighand->siglock);
Davide Libenzifba2afa2007-05-10 22:23:13 -070055
56 return events;
57}
58
59/*
60 * Copied from copy_siginfo_to_user() in kernel/signal.c
61 */
62static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
63 siginfo_t const *kinfo)
64{
65 long err;
66
67 BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
68
69 /*
Robert P. J. Day14e4a0f2008-02-03 15:12:15 +020070 * Unused members should be zero ...
Davide Libenzifba2afa2007-05-10 22:23:13 -070071 */
72 err = __clear_user(uinfo, sizeof(*uinfo));
73
74 /*
75 * If you change siginfo_t structure, please be sure
76 * this code is fixed accordingly.
77 */
Davide Libenzi96358de2007-10-16 23:30:23 -070078 err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
79 err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
80 err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code);
Davide Libenzifba2afa2007-05-10 22:23:13 -070081 switch (kinfo->si_code & __SI_MASK) {
82 case __SI_KILL:
Davide Libenzi96358de2007-10-16 23:30:23 -070083 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
84 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
Davide Libenzifba2afa2007-05-10 22:23:13 -070085 break;
86 case __SI_TIMER:
Davide Libenzi96358de2007-10-16 23:30:23 -070087 err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
88 err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
89 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
Davide Libenzifba2afa2007-05-10 22:23:13 -070090 break;
91 case __SI_POLL:
Davide Libenzi96358de2007-10-16 23:30:23 -070092 err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
93 err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
Davide Libenzifba2afa2007-05-10 22:23:13 -070094 break;
95 case __SI_FAULT:
Davide Libenzi96358de2007-10-16 23:30:23 -070096 err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
Davide Libenzifba2afa2007-05-10 22:23:13 -070097#ifdef __ARCH_SI_TRAPNO
Davide Libenzi96358de2007-10-16 23:30:23 -070098 err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
Davide Libenzifba2afa2007-05-10 22:23:13 -070099#endif
100 break;
101 case __SI_CHLD:
Davide Libenzi96358de2007-10-16 23:30:23 -0700102 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
103 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
104 err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
105 err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
106 err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700107 break;
108 case __SI_RT: /* This is not generated by the kernel as of now. */
109 case __SI_MESGQ: /* But this is */
Davide Libenzi96358de2007-10-16 23:30:23 -0700110 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
111 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
112 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700113 break;
Davide Libenzi0859ab52008-04-10 21:29:29 -0700114 default:
115 /*
116 * This case catches also the signals queued by sigqueue().
117 */
Davide Libenzi96358de2007-10-16 23:30:23 -0700118 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
119 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
Davide Libenzi0859ab52008-04-10 21:29:29 -0700120 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
121 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700122 break;
123 }
124
125 return err ? -EFAULT: sizeof(*uinfo);
126}
127
Davi Arnautb3762bf2007-05-23 13:58:04 -0700128static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
129 int nonblock)
130{
131 ssize_t ret;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700132 DECLARE_WAITQUEUE(wait, current);
133
Davide Libenzib8fceee2007-09-20 12:40:16 -0700134 spin_lock_irq(&current->sighand->siglock);
135 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700136 switch (ret) {
137 case 0:
138 if (!nonblock)
139 break;
140 ret = -EAGAIN;
141 default:
Davide Libenzib8fceee2007-09-20 12:40:16 -0700142 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700143 return ret;
144 }
145
Davide Libenzib8fceee2007-09-20 12:40:16 -0700146 add_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700147 for (;;) {
148 set_current_state(TASK_INTERRUPTIBLE);
Davide Libenzib8fceee2007-09-20 12:40:16 -0700149 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700150 if (ret != 0)
151 break;
152 if (signal_pending(current)) {
153 ret = -ERESTARTSYS;
154 break;
155 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700156 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700157 schedule();
Davide Libenzib8fceee2007-09-20 12:40:16 -0700158 spin_lock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700159 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700160 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700161
Davide Libenzib8fceee2007-09-20 12:40:16 -0700162 remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700163 __set_current_state(TASK_RUNNING);
164
165 return ret;
166}
167
Davide Libenzifba2afa2007-05-10 22:23:13 -0700168/*
Davide Libenzib8fceee2007-09-20 12:40:16 -0700169 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
170 * error code. The "count" parameter must be at least the size of a
171 * "struct signalfd_siginfo".
Davide Libenzifba2afa2007-05-10 22:23:13 -0700172 */
173static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
174 loff_t *ppos)
175{
176 struct signalfd_ctx *ctx = file->private_data;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700177 struct signalfd_siginfo __user *siginfo;
178 int nonblock = file->f_flags & O_NONBLOCK;
179 ssize_t ret, total = 0;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700180 siginfo_t info;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700181
Davi Arnautb3762bf2007-05-23 13:58:04 -0700182 count /= sizeof(struct signalfd_siginfo);
183 if (!count)
Davide Libenzifba2afa2007-05-10 22:23:13 -0700184 return -EINVAL;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700185
Davi Arnautb3762bf2007-05-23 13:58:04 -0700186 siginfo = (struct signalfd_siginfo __user *) buf;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700187 do {
188 ret = signalfd_dequeue(ctx, &info, nonblock);
189 if (unlikely(ret <= 0))
190 break;
191 ret = signalfd_copyinfo(siginfo, &info);
192 if (ret < 0)
193 break;
194 siginfo++;
195 total += ret;
196 nonblock = 1;
197 } while (--count);
198
Davide Libenzib8fceee2007-09-20 12:40:16 -0700199 return total ? total: ret;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700200}
201
202static const struct file_operations signalfd_fops = {
203 .release = signalfd_release,
204 .poll = signalfd_poll,
205 .read = signalfd_read,
206};
207
Davide Libenzifba2afa2007-05-10 22:23:13 -0700208asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask)
209{
Davide Libenzifba2afa2007-05-10 22:23:13 -0700210 sigset_t sigmask;
211 struct signalfd_ctx *ctx;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700212
213 if (sizemask != sizeof(sigset_t) ||
214 copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
Ulrich Drepperf50cadaa2007-07-26 10:40:55 -0700215 return -EINVAL;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700216 sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
217 signotset(&sigmask);
218
219 if (ufd == -1) {
220 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
221 if (!ctx)
222 return -ENOMEM;
223
Davide Libenzifba2afa2007-05-10 22:23:13 -0700224 ctx->sigmask = sigmask;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700225
226 /*
227 * When we call this, the initialization must be complete, since
228 * anon_inode_getfd() will install the fd.
229 */
Al Viro2030a422008-02-23 06:46:49 -0500230 ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx);
231 if (ufd < 0)
232 kfree(ctx);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700233 } else {
Al Viro2030a422008-02-23 06:46:49 -0500234 struct file *file = fget(ufd);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700235 if (!file)
236 return -EBADF;
237 ctx = file->private_data;
238 if (file->f_op != &signalfd_fops) {
239 fput(file);
240 return -EINVAL;
241 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700242 spin_lock_irq(&current->sighand->siglock);
243 ctx->sigmask = sigmask;
244 spin_unlock_irq(&current->sighand->siglock);
245
246 wake_up(&current->sighand->signalfd_wqh);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700247 fput(file);
248 }
249
250 return ufd;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700251}