~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/signalfd.c

Version: ~ [ linux-5.8 ] ~ [ linux-5.7.14 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.57 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.138 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.193 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.232 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.232 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.85 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *  fs/signalfd.c
  4  *
  5  *  Copyright (C) 2003  Linus Torvalds
  6  *
  7  *  Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org>
  8  *      Changed ->read() to return a siginfo strcture instead of signal number.
  9  *      Fixed locking in ->poll().
 10  *      Added sighand-detach notification.
 11  *      Added fd re-use in sys_signalfd() syscall.
 12  *      Now using anonymous inode source.
 13  *      Thanks to Oleg Nesterov for useful code review and suggestions.
 14  *      More comments and suggestions from Arnd Bergmann.
 15  *  Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
 16  *      Retrieve multiple signals with one read() call
 17  *  Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
 18  *      Attach to the sighand only during read() and poll().
 19  */
 20 
 21 #include <linux/file.h>
 22 #include <linux/poll.h>
 23 #include <linux/init.h>
 24 #include <linux/fs.h>
 25 #include <linux/sched.h>
 26 #include <linux/slab.h>
 27 #include <linux/kernel.h>
 28 #include <linux/signal.h>
 29 #include <linux/list.h>
 30 #include <linux/anon_inodes.h>
 31 #include <linux/signalfd.h>
 32 #include <linux/syscalls.h>
 33 #include <linux/proc_fs.h>
 34 #include <linux/compat.h>
 35 
 36 void signalfd_cleanup(struct sighand_struct *sighand)
 37 {
 38         wait_queue_head_t *wqh = &sighand->signalfd_wqh;
 39         /*
 40          * The lockless check can race with remove_wait_queue() in progress,
 41          * but in this case its caller should run under rcu_read_lock() and
 42          * sighand_cachep is SLAB_TYPESAFE_BY_RCU, we can safely return.
 43          */
 44         if (likely(!waitqueue_active(wqh)))
 45                 return;
 46 
 47         /* wait_queue_entry_t->func(POLLFREE) should do remove_wait_queue() */
 48         wake_up_poll(wqh, EPOLLHUP | POLLFREE);
 49 }
 50 
 51 struct signalfd_ctx {
 52         sigset_t sigmask;
 53 };
 54 
 55 static int signalfd_release(struct inode *inode, struct file *file)
 56 {
 57         kfree(file->private_data);
 58         return 0;
 59 }
 60 
 61 static __poll_t signalfd_poll(struct file *file, poll_table *wait)
 62 {
 63         struct signalfd_ctx *ctx = file->private_data;
 64         __poll_t events = 0;
 65 
 66         poll_wait(file, &current->sighand->signalfd_wqh, wait);
 67 
 68         spin_lock_irq(&current->sighand->siglock);
 69         if (next_signal(&current->pending, &ctx->sigmask) ||
 70             next_signal(&current->signal->shared_pending,
 71                         &ctx->sigmask))
 72                 events |= EPOLLIN;
 73         spin_unlock_irq(&current->sighand->siglock);
 74 
 75         return events;
 76 }
 77 
 78 /*
 79  * Copied from copy_siginfo_to_user() in kernel/signal.c
 80  */
 81 static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 82                              kernel_siginfo_t const *kinfo)
 83 {
 84         struct signalfd_siginfo new;
 85 
 86         BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
 87 
 88         /*
 89          * Unused members should be zero ...
 90          */
 91         memset(&new, 0, sizeof(new));
 92 
 93         /*
 94          * If you change siginfo_t structure, please be sure
 95          * this code is fixed accordingly.
 96          */
 97         new.ssi_signo = kinfo->si_signo;
 98         new.ssi_errno = kinfo->si_errno;
 99         new.ssi_code  = kinfo->si_code;
100         switch (siginfo_layout(kinfo->si_signo, kinfo->si_code)) {
101         case SIL_KILL:
102                 new.ssi_pid = kinfo->si_pid;
103                 new.ssi_uid = kinfo->si_uid;
104                 break;
105         case SIL_TIMER:
106                 new.ssi_tid = kinfo->si_tid;
107                 new.ssi_overrun = kinfo->si_overrun;
108                 new.ssi_ptr = (long) kinfo->si_ptr;
109                 new.ssi_int = kinfo->si_int;
110                 break;
111         case SIL_POLL:
112                 new.ssi_band = kinfo->si_band;
113                 new.ssi_fd   = kinfo->si_fd;
114                 break;
115         case SIL_FAULT_BNDERR:
116         case SIL_FAULT_PKUERR:
117                 /*
118                  * Fall through to the SIL_FAULT case.  Both SIL_FAULT_BNDERR
119                  * and SIL_FAULT_PKUERR are only generated by faults that
120                  * deliver them synchronously to userspace.  In case someone
121                  * injects one of these signals and signalfd catches it treat
122                  * it as SIL_FAULT.
123                  */
124         case SIL_FAULT:
125                 new.ssi_addr = (long) kinfo->si_addr;
126 #ifdef __ARCH_SI_TRAPNO
127                 new.ssi_trapno = kinfo->si_trapno;
128 #endif
129                 break;
130         case SIL_FAULT_MCEERR:
131                 new.ssi_addr = (long) kinfo->si_addr;
132 #ifdef __ARCH_SI_TRAPNO
133                 new.ssi_trapno = kinfo->si_trapno;
134 #endif
135                 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
136                 break;
137         case SIL_CHLD:
138                 new.ssi_pid    = kinfo->si_pid;
139                 new.ssi_uid    = kinfo->si_uid;
140                 new.ssi_status = kinfo->si_status;
141                 new.ssi_utime  = kinfo->si_utime;
142                 new.ssi_stime  = kinfo->si_stime;
143                 break;
144         case SIL_RT:
145                 /*
146                  * This case catches also the signals queued by sigqueue().
147                  */
148                 new.ssi_pid = kinfo->si_pid;
149                 new.ssi_uid = kinfo->si_uid;
150                 new.ssi_ptr = (long) kinfo->si_ptr;
151                 new.ssi_int = kinfo->si_int;
152                 break;
153         case SIL_SYS:
154                 new.ssi_call_addr = (long) kinfo->si_call_addr;
155                 new.ssi_syscall   = kinfo->si_syscall;
156                 new.ssi_arch      = kinfo->si_arch;
157                 break;
158         }
159 
160         if (copy_to_user(uinfo, &new, sizeof(struct signalfd_siginfo)))
161                 return -EFAULT;
162 
163         return sizeof(*uinfo);
164 }
165 
166 static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, kernel_siginfo_t *info,
167                                 int nonblock)
168 {
169         ssize_t ret;
170         DECLARE_WAITQUEUE(wait, current);
171 
172         spin_lock_irq(&current->sighand->siglock);
173         ret = dequeue_signal(current, &ctx->sigmask, info);
174         switch (ret) {
175         case 0:
176                 if (!nonblock)
177                         break;
178                 ret = -EAGAIN;
179                 /* fall through */
180         default:
181                 spin_unlock_irq(&current->sighand->siglock);
182                 return ret;
183         }
184 
185         add_wait_queue(&current->sighand->signalfd_wqh, &wait);
186         for (;;) {
187                 set_current_state(TASK_INTERRUPTIBLE);
188                 ret = dequeue_signal(current, &ctx->sigmask, info);
189                 if (ret != 0)
190                         break;
191                 if (signal_pending(current)) {
192                         ret = -ERESTARTSYS;
193                         break;
194                 }
195                 spin_unlock_irq(&current->sighand->siglock);
196                 schedule();
197                 spin_lock_irq(&current->sighand->siglock);
198         }
199         spin_unlock_irq(&current->sighand->siglock);
200 
201         remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
202         __set_current_state(TASK_RUNNING);
203 
204         return ret;
205 }
206 
207 /*
208  * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
209  * error code. The "count" parameter must be at least the size of a
210  * "struct signalfd_siginfo".
211  */
212 static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
213                              loff_t *ppos)
214 {
215         struct signalfd_ctx *ctx = file->private_data;
216         struct signalfd_siginfo __user *siginfo;
217         int nonblock = file->f_flags & O_NONBLOCK;
218         ssize_t ret, total = 0;
219         kernel_siginfo_t info;
220 
221         count /= sizeof(struct signalfd_siginfo);
222         if (!count)
223                 return -EINVAL;
224 
225         siginfo = (struct signalfd_siginfo __user *) buf;
226         do {
227                 ret = signalfd_dequeue(ctx, &info, nonblock);
228                 if (unlikely(ret <= 0))
229                         break;
230                 ret = signalfd_copyinfo(siginfo, &info);
231                 if (ret < 0)
232                         break;
233                 siginfo++;
234                 total += ret;
235                 nonblock = 1;
236         } while (--count);
237 
238         return total ? total: ret;
239 }
240 
241 #ifdef CONFIG_PROC_FS
242 static void signalfd_show_fdinfo(struct seq_file *m, struct file *f)
243 {
244         struct signalfd_ctx *ctx = f->private_data;
245         sigset_t sigmask;
246 
247         sigmask = ctx->sigmask;
248         signotset(&sigmask);
249         render_sigset_t(m, "sigmask:\t", &sigmask);
250 }
251 #endif
252 
253 static const struct file_operations signalfd_fops = {
254 #ifdef CONFIG_PROC_FS
255         .show_fdinfo    = signalfd_show_fdinfo,
256 #endif
257         .release        = signalfd_release,
258         .poll           = signalfd_poll,
259         .read           = signalfd_read,
260         .llseek         = noop_llseek,
261 };
262 
263 static int do_signalfd4(int ufd, sigset_t *mask, int flags)
264 {
265         struct signalfd_ctx *ctx;
266 
267         /* Check the SFD_* constants for consistency.  */
268         BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
269         BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
270 
271         if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
272                 return -EINVAL;
273 
274         sigdelsetmask(mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
275         signotset(mask);
276 
277         if (ufd == -1) {
278                 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
279                 if (!ctx)
280                         return -ENOMEM;
281 
282                 ctx->sigmask = *mask;
283 
284                 /*
285                  * When we call this, the initialization must be complete, since
286                  * anon_inode_getfd() will install the fd.
287                  */
288                 ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
289                                        O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
290                 if (ufd < 0)
291                         kfree(ctx);
292         } else {
293                 struct fd f = fdget(ufd);
294                 if (!f.file)
295                         return -EBADF;
296                 ctx = f.file->private_data;
297                 if (f.file->f_op != &signalfd_fops) {
298                         fdput(f);
299                         return -EINVAL;
300                 }
301                 spin_lock_irq(&current->sighand->siglock);
302                 ctx->sigmask = *mask;
303                 spin_unlock_irq(&current->sighand->siglock);
304 
305                 wake_up(&current->sighand->signalfd_wqh);
306                 fdput(f);
307         }
308 
309         return ufd;
310 }
311 
312 SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
313                 size_t, sizemask, int, flags)
314 {
315         sigset_t mask;
316 
317         if (sizemask != sizeof(sigset_t) ||
318             copy_from_user(&mask, user_mask, sizeof(mask)))
319                 return -EINVAL;
320         return do_signalfd4(ufd, &mask, flags);
321 }
322 
323 SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
324                 size_t, sizemask)
325 {
326         sigset_t mask;
327 
328         if (sizemask != sizeof(sigset_t) ||
329             copy_from_user(&mask, user_mask, sizeof(mask)))
330                 return -EINVAL;
331         return do_signalfd4(ufd, &mask, 0);
332 }
333 
334 #ifdef CONFIG_COMPAT
335 static long do_compat_signalfd4(int ufd,
336                         const compat_sigset_t __user *user_mask,
337                         compat_size_t sigsetsize, int flags)
338 {
339         sigset_t mask;
340 
341         if (sigsetsize != sizeof(compat_sigset_t))
342                 return -EINVAL;
343         if (get_compat_sigset(&mask, user_mask))
344                 return -EFAULT;
345         return do_signalfd4(ufd, &mask, flags);
346 }
347 
348 COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd,
349                      const compat_sigset_t __user *, user_mask,
350                      compat_size_t, sigsetsize,
351                      int, flags)
352 {
353         return do_compat_signalfd4(ufd, user_mask, sigsetsize, flags);
354 }
355 
356 COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd,
357                      const compat_sigset_t __user *, user_mask,
358                      compat_size_t, sigsetsize)
359 {
360         return do_compat_signalfd4(ufd, user_mask, sigsetsize, 0);
361 }
362 #endif
363 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp