Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/fs/signalfd.c

  1 /*
  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.
 14  *  Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
 15  *      Retrieve multiple signals with one read() call
 16  *  Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
 17  *      Attach to the sighand only during read() and poll().
 18  */
 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/slab.h>
 26 #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>
 31 #include <linux/syscalls.h>
 32 #include <linux/proc_fs.h>
 33 #include <linux/compat.h>
 34 
 35 void signalfd_cleanup(struct sighand_struct *sighand)
 36 {
 37         wait_queue_head_t *wqh = &sighand->signalfd_wqh;
 38         /*
 39          * The lockless check can race with remove_wait_queue() in progress,
 40          * but in this case its caller should run under rcu_read_lock() and
 41          * sighand_cachep is SLAB_DESTROY_BY_RCU, we can safely return.
 42          */
 43         if (likely(!waitqueue_active(wqh)))
 44                 return;
 45 
 46         /* wait_queue_t->func(POLLFREE) should do remove_wait_queue() */
 47         wake_up_poll(wqh, POLLHUP | POLLFREE);
 48 }
 49 
 50 struct signalfd_ctx {
 51         sigset_t sigmask;
 52 };
 53 
 54 static int signalfd_release(struct inode *inode, struct file *file)
 55 {
 56         kfree(file->private_data);
 57         return 0;
 58 }
 59 
 60 static unsigned int signalfd_poll(struct file *file, poll_table *wait)
 61 {
 62         struct signalfd_ctx *ctx = file->private_data;
 63         unsigned int events = 0;
 64 
 65         poll_wait(file, &current->sighand->signalfd_wqh, wait);
 66 
 67         spin_lock_irq(&current->sighand->siglock);
 68         if (next_signal(&current->pending, &ctx->sigmask) ||
 69             next_signal(&current->signal->shared_pending,
 70                         &ctx->sigmask))
 71                 events |= POLLIN;
 72         spin_unlock_irq(&current->sighand->siglock);
 73 
 74         return events;
 75 }
 76 
 77 /*
 78  * Copied from copy_siginfo_to_user() in kernel/signal.c
 79  */
 80 static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 81                              siginfo_t const *kinfo)
 82 {
 83         long err;
 84 
 85         BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
 86 
 87         /*
 88          * Unused members should be zero ...
 89          */
 90         err = __clear_user(uinfo, sizeof(*uinfo));
 91 
 92         /*
 93          * If you change siginfo_t structure, please be sure
 94          * this code is fixed accordingly.
 95          */
 96         err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
 97         err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
 98         err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code);
 99         switch (kinfo->si_code & __SI_MASK) {
100         case __SI_KILL:
101                 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
102                 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
103                 break;
104         case __SI_TIMER:
105                  err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
106                  err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
107                  err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
108                  err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
109                 break;
110         case __SI_POLL:
111                 err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
112                 err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
113                 break;
114         case __SI_FAULT:
115                 err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
116 #ifdef __ARCH_SI_TRAPNO
117                 err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
118 #endif
119 #ifdef BUS_MCEERR_AO
120                 /* 
121                  * Other callers might not initialize the si_lsb field,
122                  * so check explicitly for the right codes here.
123                  */
124                 if (kinfo->si_signo == SIGBUS &&
125                     (kinfo->si_code == BUS_MCEERR_AR ||
126                      kinfo->si_code == BUS_MCEERR_AO))
127                         err |= __put_user((short) kinfo->si_addr_lsb,
128                                           &uinfo->ssi_addr_lsb);
129 #endif
130                 break;
131         case __SI_CHLD:
132                 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
133                 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
134                 err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
135                 err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
136                 err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
137                 break;
138         case __SI_RT: /* This is not generated by the kernel as of now. */
139         case __SI_MESGQ: /* But this is */
140                 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
141                 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
142                 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
143                 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
144                 break;
145         default:
146                 /*
147                  * This case catches also the signals queued by sigqueue().
148                  */
149                 err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
150                 err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
151                 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
152                 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
153                 break;
154         }
155 
156         return err ? -EFAULT: sizeof(*uinfo);
157 }
158 
159 static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
160                                 int nonblock)
161 {
162         ssize_t ret;
163         DECLARE_WAITQUEUE(wait, current);
164 
165         spin_lock_irq(&current->sighand->siglock);
166         ret = dequeue_signal(current, &ctx->sigmask, info);
167         switch (ret) {
168         case 0:
169                 if (!nonblock)
170                         break;
171                 ret = -EAGAIN;
172         default:
173                 spin_unlock_irq(&current->sighand->siglock);
174                 return ret;
175         }
176 
177         add_wait_queue(&current->sighand->signalfd_wqh, &wait);
178         for (;;) {
179                 set_current_state(TASK_INTERRUPTIBLE);
180                 ret = dequeue_signal(current, &ctx->sigmask, info);
181                 if (ret != 0)
182                         break;
183                 if (signal_pending(current)) {
184                         ret = -ERESTARTSYS;
185                         break;
186                 }
187                 spin_unlock_irq(&current->sighand->siglock);
188                 schedule();
189                 spin_lock_irq(&current->sighand->siglock);
190         }
191         spin_unlock_irq(&current->sighand->siglock);
192 
193         remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
194         __set_current_state(TASK_RUNNING);
195 
196         return ret;
197 }
198 
199 /*
200  * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
201  * error code. The "count" parameter must be at least the size of a
202  * "struct signalfd_siginfo".
203  */
204 static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
205                              loff_t *ppos)
206 {
207         struct signalfd_ctx *ctx = file->private_data;
208         struct signalfd_siginfo __user *siginfo;
209         int nonblock = file->f_flags & O_NONBLOCK;
210         ssize_t ret, total = 0;
211         siginfo_t info;
212 
213         count /= sizeof(struct signalfd_siginfo);
214         if (!count)
215                 return -EINVAL;
216 
217         siginfo = (struct signalfd_siginfo __user *) buf;
218         do {
219                 ret = signalfd_dequeue(ctx, &info, nonblock);
220                 if (unlikely(ret <= 0))
221                         break;
222                 ret = signalfd_copyinfo(siginfo, &info);
223                 if (ret < 0)
224                         break;
225                 siginfo++;
226                 total += ret;
227                 nonblock = 1;
228         } while (--count);
229 
230         return total ? total: ret;
231 }
232 
233 #ifdef CONFIG_PROC_FS
234 static void signalfd_show_fdinfo(struct seq_file *m, struct file *f)
235 {
236         struct signalfd_ctx *ctx = f->private_data;
237         sigset_t sigmask;
238 
239         sigmask = ctx->sigmask;
240         signotset(&sigmask);
241         render_sigset_t(m, "sigmask:\t", &sigmask);
242 }
243 #endif
244 
245 static const struct file_operations signalfd_fops = {
246 #ifdef CONFIG_PROC_FS
247         .show_fdinfo    = signalfd_show_fdinfo,
248 #endif
249         .release        = signalfd_release,
250         .poll           = signalfd_poll,
251         .read           = signalfd_read,
252         .llseek         = noop_llseek,
253 };
254 
255 SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
256                 size_t, sizemask, int, flags)
257 {
258         sigset_t sigmask;
259         struct signalfd_ctx *ctx;
260 
261         /* Check the SFD_* constants for consistency.  */
262         BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
263         BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
264 
265         if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
266                 return -EINVAL;
267 
268         if (sizemask != sizeof(sigset_t) ||
269             copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
270                 return -EINVAL;
271         sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
272         signotset(&sigmask);
273 
274         if (ufd == -1) {
275                 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
276                 if (!ctx)
277                         return -ENOMEM;
278 
279                 ctx->sigmask = sigmask;
280 
281                 /*
282                  * When we call this, the initialization must be complete, since
283                  * anon_inode_getfd() will install the fd.
284                  */
285                 ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
286                                        O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
287                 if (ufd < 0)
288                         kfree(ctx);
289         } else {
290                 struct fd f = fdget(ufd);
291                 if (!f.file)
292                         return -EBADF;
293                 ctx = f.file->private_data;
294                 if (f.file->f_op != &signalfd_fops) {
295                         fdput(f);
296                         return -EINVAL;
297                 }
298                 spin_lock_irq(&current->sighand->siglock);
299                 ctx->sigmask = sigmask;
300                 spin_unlock_irq(&current->sighand->siglock);
301 
302                 wake_up(&current->sighand->signalfd_wqh);
303                 fdput(f);
304         }
305 
306         return ufd;
307 }
308 
309 SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
310                 size_t, sizemask)
311 {
312         return sys_signalfd4(ufd, user_mask, sizemask, 0);
313 }
314 
315 #ifdef CONFIG_COMPAT
316 COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd,
317                      const compat_sigset_t __user *,sigmask,
318                      compat_size_t, sigsetsize,
319                      int, flags)
320 {
321         compat_sigset_t ss32;
322         sigset_t tmp;
323         sigset_t __user *ksigmask;
324 
325         if (sigsetsize != sizeof(compat_sigset_t))
326                 return -EINVAL;
327         if (copy_from_user(&ss32, sigmask, sizeof(ss32)))
328                 return -EFAULT;
329         sigset_from_compat(&tmp, &ss32);
330         ksigmask = compat_alloc_user_space(sizeof(sigset_t));
331         if (copy_to_user(ksigmask, &tmp, sizeof(sigset_t)))
332                 return -EFAULT;
333 
334         return sys_signalfd4(ufd, ksigmask, sizeof(sigset_t), flags);
335 }
336 
337 COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd,
338                      const compat_sigset_t __user *,sigmask,
339                      compat_size_t, sigsetsize)
340 {
341         return compat_sys_signalfd4(ufd, sigmask, sigsetsize, 0);
342 }
343 #endif
344 

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us