blob: 492465b451ddd34f6f60214fb48224687649faa9 [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>
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
Hidetoshi Setob8aeec32010-10-07 15:31:31 +0900102#ifdef BUS_MCEERR_AO
103 /*
104 * Other callers might not initialize the si_lsb field,
105 * so check explicitly for the right codes here.
106 */
107 if (kinfo->si_code == BUS_MCEERR_AR ||
108 kinfo->si_code == BUS_MCEERR_AO)
109 err |= __put_user((short) kinfo->si_addr_lsb,
110 &uinfo->ssi_addr_lsb);
111#endif
Davide Libenzifba2afa2007-05-10 22:23:13 -0700112 break;
113 case __SI_CHLD:
Davide Libenzi96358de2007-10-16 23:30:23 -0700114 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
115 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
116 err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
117 err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
118 err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700119 break;
120 case __SI_RT: /* This is not generated by the kernel as of now. */
121 case __SI_MESGQ: /* But this is */
Davide Libenzi96358de2007-10-16 23:30:23 -0700122 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
123 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
124 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
Nathan Lyncha2a20c42010-08-10 18:03:08 -0700125 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700126 break;
Davide Libenzi0859ab52008-04-10 21:29:29 -0700127 default:
128 /*
129 * This case catches also the signals queued by sigqueue().
130 */
Davide Libenzi96358de2007-10-16 23:30:23 -0700131 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
132 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
Davide Libenzi0859ab52008-04-10 21:29:29 -0700133 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
134 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700135 break;
136 }
137
138 return err ? -EFAULT: sizeof(*uinfo);
139}
140
Davi Arnautb3762bf2007-05-23 13:58:04 -0700141static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
142 int nonblock)
143{
144 ssize_t ret;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700145 DECLARE_WAITQUEUE(wait, current);
146
Davide Libenzib8fceee2007-09-20 12:40:16 -0700147 spin_lock_irq(&current->sighand->siglock);
148 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700149 switch (ret) {
150 case 0:
151 if (!nonblock)
152 break;
153 ret = -EAGAIN;
154 default:
Davide Libenzib8fceee2007-09-20 12:40:16 -0700155 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700156 return ret;
157 }
158
Davide Libenzib8fceee2007-09-20 12:40:16 -0700159 add_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700160 for (;;) {
161 set_current_state(TASK_INTERRUPTIBLE);
Davide Libenzib8fceee2007-09-20 12:40:16 -0700162 ret = dequeue_signal(current, &ctx->sigmask, info);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700163 if (ret != 0)
164 break;
165 if (signal_pending(current)) {
166 ret = -ERESTARTSYS;
167 break;
168 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700169 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700170 schedule();
Davide Libenzib8fceee2007-09-20 12:40:16 -0700171 spin_lock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700172 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700173 spin_unlock_irq(&current->sighand->siglock);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700174
Davide Libenzib8fceee2007-09-20 12:40:16 -0700175 remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
Davi Arnautb3762bf2007-05-23 13:58:04 -0700176 __set_current_state(TASK_RUNNING);
177
178 return ret;
179}
180
Davide Libenzifba2afa2007-05-10 22:23:13 -0700181/*
Davide Libenzib8fceee2007-09-20 12:40:16 -0700182 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
183 * error code. The "count" parameter must be at least the size of a
184 * "struct signalfd_siginfo".
Davide Libenzifba2afa2007-05-10 22:23:13 -0700185 */
186static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
187 loff_t *ppos)
188{
189 struct signalfd_ctx *ctx = file->private_data;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700190 struct signalfd_siginfo __user *siginfo;
191 int nonblock = file->f_flags & O_NONBLOCK;
192 ssize_t ret, total = 0;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700193 siginfo_t info;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700194
Davi Arnautb3762bf2007-05-23 13:58:04 -0700195 count /= sizeof(struct signalfd_siginfo);
196 if (!count)
Davide Libenzifba2afa2007-05-10 22:23:13 -0700197 return -EINVAL;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700198
Davi Arnautb3762bf2007-05-23 13:58:04 -0700199 siginfo = (struct signalfd_siginfo __user *) buf;
Davi Arnautb3762bf2007-05-23 13:58:04 -0700200 do {
201 ret = signalfd_dequeue(ctx, &info, nonblock);
202 if (unlikely(ret <= 0))
203 break;
204 ret = signalfd_copyinfo(siginfo, &info);
205 if (ret < 0)
206 break;
207 siginfo++;
208 total += ret;
209 nonblock = 1;
210 } while (--count);
211
Davide Libenzib8fceee2007-09-20 12:40:16 -0700212 return total ? total: ret;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700213}
214
215static const struct file_operations signalfd_fops = {
216 .release = signalfd_release,
217 .poll = signalfd_poll,
218 .read = signalfd_read,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200219 .llseek = noop_llseek,
Davide Libenzifba2afa2007-05-10 22:23:13 -0700220};
221
Heiko Carstens836f92a2009-01-14 14:14:33 +0100222SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
223 size_t, sizemask, int, flags)
Davide Libenzifba2afa2007-05-10 22:23:13 -0700224{
Davide Libenzifba2afa2007-05-10 22:23:13 -0700225 sigset_t sigmask;
226 struct signalfd_ctx *ctx;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700227
Ulrich Dreppere38b36f2008-07-23 21:29:42 -0700228 /* Check the SFD_* constants for consistency. */
229 BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
230 BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
231
Ulrich Drepper5fb5e042008-07-23 21:29:37 -0700232 if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
Ulrich Drepper9deb27b2008-07-23 21:29:24 -0700233 return -EINVAL;
234
Davide Libenzifba2afa2007-05-10 22:23:13 -0700235 if (sizemask != sizeof(sigset_t) ||
236 copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
Ulrich Drepperf50cadaa2007-07-26 10:40:55 -0700237 return -EINVAL;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700238 sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
239 signotset(&sigmask);
240
241 if (ufd == -1) {
242 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
243 if (!ctx)
244 return -ENOMEM;
245
Davide Libenzifba2afa2007-05-10 22:23:13 -0700246 ctx->sigmask = sigmask;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700247
248 /*
249 * When we call this, the initialization must be complete, since
250 * anon_inode_getfd() will install the fd.
251 */
Ulrich Drepper7d9dbca2008-07-23 21:29:22 -0700252 ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
Roland Dreier628ff7c2009-12-18 09:41:24 -0800253 O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
Al Viro2030a422008-02-23 06:46:49 -0500254 if (ufd < 0)
255 kfree(ctx);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700256 } else {
Al Viro2030a422008-02-23 06:46:49 -0500257 struct file *file = fget(ufd);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700258 if (!file)
259 return -EBADF;
260 ctx = file->private_data;
261 if (file->f_op != &signalfd_fops) {
262 fput(file);
263 return -EINVAL;
264 }
Davide Libenzib8fceee2007-09-20 12:40:16 -0700265 spin_lock_irq(&current->sighand->siglock);
266 ctx->sigmask = sigmask;
267 spin_unlock_irq(&current->sighand->siglock);
268
269 wake_up(&current->sighand->signalfd_wqh);
Davide Libenzifba2afa2007-05-10 22:23:13 -0700270 fput(file);
271 }
272
273 return ufd;
Davide Libenzifba2afa2007-05-10 22:23:13 -0700274}
Ulrich Drepper9deb27b2008-07-23 21:29:24 -0700275
Heiko Carstens836f92a2009-01-14 14:14:33 +0100276SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
277 size_t, sizemask)
Ulrich Drepper9deb27b2008-07-23 21:29:24 -0700278{
279 return sys_signalfd4(ufd, user_mask, sizemask, 0);
280}