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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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090025#include <linux/slab.h>
Davide Libenzifba2afa2007-05-10 22:23:13 -070026#include <linux/kernel.h>
27#include <linux/signal.h>
28#include <linux/list.h>
29#include <linux/anon_inodes.h>
30#include <linux/signalfd.h>
Adrian Bunk7ec37df2008-02-06 01:36:48 -080031#include <linux/syscalls.h>
Davide Libenzifba2afa2007-05-10 22:23:13 -070032
33struct signalfd_ctx {
Davide Libenzifba2afa2007-05-10 22:23:13 -070034 sigset_t sigmask;
Davide Libenzifba2afa2007-05-10 22:23:13 -070035};
36
Davide Libenzifba2afa2007-05-10 22:23:13 -070037static int signalfd_release(struct inode *inode, struct file *file)
38{
Davide Libenzib8fceee2007-09-20 12:40:16 -070039 kfree(file->private_data);
Davide Libenzifba2afa2007-05-10 22:23:13 -070040 return 0;
41}
42
43static unsigned int signalfd_poll(struct file *file, poll_table *wait)
44{
45 struct signalfd_ctx *ctx = file->private_data;
46 unsigned int events = 0;
Davide Libenzifba2afa2007-05-10 22:23:13 -070047
Davide Libenzib8fceee2007-09-20 12:40:16 -070048 poll_wait(file, &current->sighand->signalfd_wqh, wait);
Davide Libenzifba2afa2007-05-10 22:23:13 -070049
Davide Libenzib8fceee2007-09-20 12:40:16 -070050 spin_lock_irq(&current->sighand->siglock);
51 if (next_signal(&current->pending, &ctx->sigmask) ||
52 next_signal(&current->signal->shared_pending,
53 &ctx->sigmask))
Davide Libenzifba2afa2007-05-10 22:23:13 -070054 events |= POLLIN;
Davide Libenzib8fceee2007-09-20 12:40:16 -070055 spin_unlock_irq(&current->sighand->siglock);
Davide Libenzifba2afa2007-05-10 22:23:13 -070056
57 return events;
58}
59
60/*
61 * Copied from copy_siginfo_to_user() in kernel/signal.c
62 */
63static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
64 siginfo_t const *kinfo)
65{
66 long err;
67
68 BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
69
70 /*
Robert P. J. Day14e4a0f2008-02-03 15:12:15 +020071 * Unused members should be zero ...
Davide Libenzifba2afa2007-05-10 22:23:13 -070072 */
73 err = __clear_user(uinfo, sizeof(*uinfo));
74
75 /*
76 * If you change siginfo_t structure, please be sure
77 * this code is fixed accordingly.
78 */
Davide Libenzi96358de2007-10-16 23:30:23 -070079 err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
80 err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
81 err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code);
Davide Libenzifba2afa2007-05-10 22:23:13 -070082 switch (kinfo->si_code & __SI_MASK) {
83 case __SI_KILL:
Davide Libenzi96358de2007-10-16 23:30:23 -070084 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
85 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
Davide Libenzifba2afa2007-05-10 22:23:13 -070086 break;
87 case __SI_TIMER:
Davide Libenzi96358de2007-10-16 23:30:23 -070088 err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
89 err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
90 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
Nathan Lyncha2a20c42010-08-10 18:03:08 -070091 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
Davide Libenzifba2afa2007-05-10 22:23:13 -070092 break;
93 case __SI_POLL:
Davide Libenzi96358de2007-10-16 23:30:23 -070094 err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
95 err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
Davide Libenzifba2afa2007-05-10 22:23:13 -070096 break;
97 case __SI_FAULT:
Davide Libenzi96358de2007-10-16 23:30:23 -070098 err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
Davide Libenzifba2afa2007-05-10 22:23:13 -070099#ifdef __ARCH_SI_TRAPNO
Davide Libenzi96358de2007-10-16 23:30:23 -0700100 err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700101#endif
102 break;
103 case __SI_CHLD:
Davide Libenzi96358de2007-10-16 23:30:23 -0700104 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
105 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
106 err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
107 err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
108 err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700109 break;
110 case __SI_RT: /* This is not generated by the kernel as of now. */
111 case __SI_MESGQ: /* But this is */
Davide Libenzi96358de2007-10-16 23:30:23 -0700112 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
113 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
114 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
Nathan Lyncha2a20c42010-08-10 18:03:08 -0700115 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700116 break;
Davide Libenzi0859ab52008-04-10 21:29:29 -0700117 default:
118 /*
119 * This case catches also the signals queued by sigqueue().
120 */
Davide Libenzi96358de2007-10-16 23:30:23 -0700121 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
122 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
Davide Libenzi0859ab52008-04-10 21:29:29 -0700123 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
124 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700125 break;
126 }
127
128 return err ? -EFAULT: sizeof(*uinfo);
129}
130
Davi Arnautb3762bf2007-05-23 13:58:04 -0700131static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
132 int nonblock)
133{
134 ssize_t ret;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700135 DECLARE_WAITQUEUE(wait, current);
136
Davide Libenzib8fceee2007-09-20 12:40:16 -0700137 spin_lock_irq(&current->sighand->siglock);
138 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700139 switch (ret) {
140 case 0:
141 if (!nonblock)
142 break;
143 ret = -EAGAIN;
144 default:
Davide Libenzib8fceee2007-09-20 12:40:16 -0700145 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700146 return ret;
147 }
148
Davide Libenzib8fceee2007-09-20 12:40:16 -0700149 add_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700150 for (;;) {
151 set_current_state(TASK_INTERRUPTIBLE);
Davide Libenzib8fceee2007-09-20 12:40:16 -0700152 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700153 if (ret != 0)
154 break;
155 if (signal_pending(current)) {
156 ret = -ERESTARTSYS;
157 break;
158 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700159 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700160 schedule();
Davide Libenzib8fceee2007-09-20 12:40:16 -0700161 spin_lock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700162 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700163 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700164
Davide Libenzib8fceee2007-09-20 12:40:16 -0700165 remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700166 __set_current_state(TASK_RUNNING);
167
168 return ret;
169}
170
Davide Libenzifba2afa2007-05-10 22:23:13 -0700171/*
Davide Libenzib8fceee2007-09-20 12:40:16 -0700172 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
173 * error code. The "count" parameter must be at least the size of a
174 * "struct signalfd_siginfo".
Davide Libenzifba2afa2007-05-10 22:23:13 -0700175 */
176static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
177 loff_t *ppos)
178{
179 struct signalfd_ctx *ctx = file->private_data;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700180 struct signalfd_siginfo __user *siginfo;
181 int nonblock = file->f_flags & O_NONBLOCK;
182 ssize_t ret, total = 0;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700183 siginfo_t info;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700184
Davi Arnautb3762bf2007-05-23 13:58:04 -0700185 count /= sizeof(struct signalfd_siginfo);
186 if (!count)
Davide Libenzifba2afa2007-05-10 22:23:13 -0700187 return -EINVAL;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700188
Davi Arnautb3762bf2007-05-23 13:58:04 -0700189 siginfo = (struct signalfd_siginfo __user *) buf;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700190 do {
191 ret = signalfd_dequeue(ctx, &info, nonblock);
192 if (unlikely(ret <= 0))
193 break;
194 ret = signalfd_copyinfo(siginfo, &info);
195 if (ret < 0)
196 break;
197 siginfo++;
198 total += ret;
199 nonblock = 1;
200 } while (--count);
201
Davide Libenzib8fceee2007-09-20 12:40:16 -0700202 return total ? total: ret;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700203}
204
205static const struct file_operations signalfd_fops = {
206 .release = signalfd_release,
207 .poll = signalfd_poll,
208 .read = signalfd_read,
209};
210
Heiko Carstens836f92a2009-01-14 14:14:33 +0100211SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
212 size_t, sizemask, int, flags)
Davide Libenzifba2afa2007-05-10 22:23:13 -0700213{
Davide Libenzifba2afa2007-05-10 22:23:13 -0700214 sigset_t sigmask;
215 struct signalfd_ctx *ctx;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700216
Ulrich Dreppere38b36f2008-07-23 21:29:42 -0700217 /* Check the SFD_* constants for consistency. */
218 BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
219 BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
220
Ulrich Drepper5fb5e042008-07-23 21:29:37 -0700221 if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
Ulrich Drepper9deb27b2008-07-23 21:29:24 -0700222 return -EINVAL;
223
Davide Libenzifba2afa2007-05-10 22:23:13 -0700224 if (sizemask != sizeof(sigset_t) ||
225 copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
Ulrich Drepperf50cada2007-07-26 10:40:55 -0700226 return -EINVAL;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700227 sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
228 signotset(&sigmask);
229
230 if (ufd == -1) {
231 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
232 if (!ctx)
233 return -ENOMEM;
234
Davide Libenzifba2afa2007-05-10 22:23:13 -0700235 ctx->sigmask = sigmask;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700236
237 /*
238 * When we call this, the initialization must be complete, since
239 * anon_inode_getfd() will install the fd.
240 */
Ulrich Drepper7d9dbca2008-07-23 21:29:22 -0700241 ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
Roland Dreier628ff7c2009-12-18 09:41:24 -0800242 O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
Al Viro2030a422008-02-23 06:46:49 -0500243 if (ufd < 0)
244 kfree(ctx);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700245 } else {
Al Viro2030a422008-02-23 06:46:49 -0500246 struct file *file = fget(ufd);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700247 if (!file)
248 return -EBADF;
249 ctx = file->private_data;
250 if (file->f_op != &signalfd_fops) {
251 fput(file);
252 return -EINVAL;
253 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700254 spin_lock_irq(&current->sighand->siglock);
255 ctx->sigmask = sigmask;
256 spin_unlock_irq(&current->sighand->siglock);
257
258 wake_up(&current->sighand->signalfd_wqh);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700259 fput(file);
260 }
261
262 return ufd;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700263}
Ulrich Drepper9deb27b2008-07-23 21:29:24 -0700264
Heiko Carstens836f92a2009-01-14 14:14:33 +0100265SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
266 size_t, sizemask)
Ulrich Drepper9deb27b2008-07-23 21:29:24 -0700267{
268 return sys_signalfd4(ufd, user_mask, sizemask, 0);
269}