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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;
114 default: /* this is just in case for now ... */
Davide Libenzi96358de2007-10-16 23:30:23 -0700115 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
116 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700117 break;
118 }
119
120 return err ? -EFAULT: sizeof(*uinfo);
121}
122
Davi Arnautb3762bf2007-05-23 13:58:04 -0700123static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
124 int nonblock)
125{
126 ssize_t ret;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700127 DECLARE_WAITQUEUE(wait, current);
128
Davide Libenzib8fceee2007-09-20 12:40:16 -0700129 spin_lock_irq(&current->sighand->siglock);
130 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700131 switch (ret) {
132 case 0:
133 if (!nonblock)
134 break;
135 ret = -EAGAIN;
136 default:
Davide Libenzib8fceee2007-09-20 12:40:16 -0700137 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700138 return ret;
139 }
140
Davide Libenzib8fceee2007-09-20 12:40:16 -0700141 add_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700142 for (;;) {
143 set_current_state(TASK_INTERRUPTIBLE);
Davide Libenzib8fceee2007-09-20 12:40:16 -0700144 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700145 if (ret != 0)
146 break;
147 if (signal_pending(current)) {
148 ret = -ERESTARTSYS;
149 break;
150 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700151 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700152 schedule();
Davide Libenzib8fceee2007-09-20 12:40:16 -0700153 spin_lock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700154 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700155 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700156
Davide Libenzib8fceee2007-09-20 12:40:16 -0700157 remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700158 __set_current_state(TASK_RUNNING);
159
160 return ret;
161}
162
Davide Libenzifba2afa2007-05-10 22:23:13 -0700163/*
Davide Libenzib8fceee2007-09-20 12:40:16 -0700164 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
165 * error code. The "count" parameter must be at least the size of a
166 * "struct signalfd_siginfo".
Davide Libenzifba2afa2007-05-10 22:23:13 -0700167 */
168static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
169 loff_t *ppos)
170{
171 struct signalfd_ctx *ctx = file->private_data;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700172 struct signalfd_siginfo __user *siginfo;
173 int nonblock = file->f_flags & O_NONBLOCK;
174 ssize_t ret, total = 0;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700175 siginfo_t info;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700176
Davi Arnautb3762bf2007-05-23 13:58:04 -0700177 count /= sizeof(struct signalfd_siginfo);
178 if (!count)
Davide Libenzifba2afa2007-05-10 22:23:13 -0700179 return -EINVAL;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700180
Davi Arnautb3762bf2007-05-23 13:58:04 -0700181 siginfo = (struct signalfd_siginfo __user *) buf;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700182 do {
183 ret = signalfd_dequeue(ctx, &info, nonblock);
184 if (unlikely(ret <= 0))
185 break;
186 ret = signalfd_copyinfo(siginfo, &info);
187 if (ret < 0)
188 break;
189 siginfo++;
190 total += ret;
191 nonblock = 1;
192 } while (--count);
193
Davide Libenzib8fceee2007-09-20 12:40:16 -0700194 return total ? total: ret;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700195}
196
197static const struct file_operations signalfd_fops = {
198 .release = signalfd_release,
199 .poll = signalfd_poll,
200 .read = signalfd_read,
201};
202
Davide Libenzifba2afa2007-05-10 22:23:13 -0700203asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask)
204{
205 int error;
206 sigset_t sigmask;
207 struct signalfd_ctx *ctx;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700208 struct file *file;
209 struct inode *inode;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700210
211 if (sizemask != sizeof(sigset_t) ||
212 copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
Ulrich Drepperf50cada2007-07-26 10:40:55 -0700213 return -EINVAL;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700214 sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
215 signotset(&sigmask);
216
217 if (ufd == -1) {
218 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
219 if (!ctx)
220 return -ENOMEM;
221
Davide Libenzifba2afa2007-05-10 22:23:13 -0700222 ctx->sigmask = sigmask;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700223
224 /*
225 * When we call this, the initialization must be complete, since
226 * anon_inode_getfd() will install the fd.
227 */
228 error = anon_inode_getfd(&ufd, &inode, &file, "[signalfd]",
229 &signalfd_fops, ctx);
230 if (error)
231 goto err_fdalloc;
232 } else {
233 file = fget(ufd);
234 if (!file)
235 return -EBADF;
236 ctx = file->private_data;
237 if (file->f_op != &signalfd_fops) {
238 fput(file);
239 return -EINVAL;
240 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700241 spin_lock_irq(&current->sighand->siglock);
242 ctx->sigmask = sigmask;
243 spin_unlock_irq(&current->sighand->siglock);
244
245 wake_up(&current->sighand->signalfd_wqh);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700246 fput(file);
247 }
248
249 return ufd;
250
251err_fdalloc:
Davide Libenzib8fceee2007-09-20 12:40:16 -0700252 kfree(ctx);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700253 return error;
254}
255