337 lines
8.8 KiB
C
337 lines
8.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* fs/signalfd.c
|
|
*
|
|
* Copyright (C) 2003 Linus Torvalds
|
|
*
|
|
* Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org>
|
|
* Changed ->read() to return a siginfo strcture instead of signal number.
|
|
* Fixed locking in ->poll().
|
|
* Added sighand-detach notification.
|
|
* Added fd re-use in sys_signalfd() syscall.
|
|
* Now using anonymous inode source.
|
|
* Thanks to Oleg Nesterov for useful code review and suggestions.
|
|
* More comments and suggestions from Arnd Bergmann.
|
|
* Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
|
|
* Retrieve multiple signals with one read() call
|
|
* Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
|
|
* Attach to the sighand only during read() and poll().
|
|
*/
|
|
|
|
#include <linux/file.h>
|
|
#include <linux/poll.h>
|
|
#include <linux/init.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/signal.h>
|
|
#include <linux/list.h>
|
|
#include <linux/anon_inodes.h>
|
|
#include <linux/signalfd.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/proc_fs.h>
|
|
#include <linux/compat.h>
|
|
|
|
void signalfd_cleanup(struct sighand_struct *sighand)
|
|
{
|
|
wait_queue_head_t *wqh = &sighand->signalfd_wqh;
|
|
/*
|
|
* The lockless check can race with remove_wait_queue() in progress,
|
|
* but in this case its caller should run under rcu_read_lock() and
|
|
* sighand_cachep is SLAB_TYPESAFE_BY_RCU, we can safely return.
|
|
*/
|
|
if (likely(!waitqueue_active(wqh)))
|
|
return;
|
|
|
|
/* wait_queue_entry_t->func(POLLFREE) should do remove_wait_queue() */
|
|
wake_up_poll(wqh, EPOLLHUP | POLLFREE);
|
|
}
|
|
|
|
struct signalfd_ctx {
|
|
sigset_t sigmask;
|
|
};
|
|
|
|
static int signalfd_release(struct inode *inode, struct file *file)
|
|
{
|
|
kfree(file->private_data);
|
|
return 0;
|
|
}
|
|
|
|
static __poll_t signalfd_poll(struct file *file, poll_table *wait)
|
|
{
|
|
struct signalfd_ctx *ctx = file->private_data;
|
|
__poll_t events = 0;
|
|
|
|
poll_wait(file, ¤t->sighand->signalfd_wqh, wait);
|
|
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
if (next_signal(¤t->pending, &ctx->sigmask) ||
|
|
next_signal(¤t->signal->shared_pending,
|
|
&ctx->sigmask))
|
|
events |= EPOLLIN;
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
|
|
return events;
|
|
}
|
|
|
|
/*
|
|
* Copied from copy_siginfo_to_user() in kernel/signal.c
|
|
*/
|
|
static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
|
|
siginfo_t const *kinfo)
|
|
{
|
|
long err;
|
|
|
|
BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
|
|
|
|
/*
|
|
* Unused members should be zero ...
|
|
*/
|
|
err = __clear_user(uinfo, sizeof(*uinfo));
|
|
|
|
/*
|
|
* If you change siginfo_t structure, please be sure
|
|
* this code is fixed accordingly.
|
|
*/
|
|
err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
|
|
err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
|
|
err |= __put_user(kinfo->si_code, &uinfo->ssi_code);
|
|
switch (siginfo_layout(kinfo->si_signo, kinfo->si_code)) {
|
|
case SIL_KILL:
|
|
err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
|
|
err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
|
|
break;
|
|
case SIL_TIMER:
|
|
err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
|
|
err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
|
|
err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
|
|
err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
|
|
break;
|
|
case SIL_POLL:
|
|
err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
|
|
err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
|
|
break;
|
|
case SIL_FAULT:
|
|
err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
|
|
#ifdef __ARCH_SI_TRAPNO
|
|
err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
|
|
#endif
|
|
#ifdef BUS_MCEERR_AO
|
|
/*
|
|
* Other callers might not initialize the si_lsb field,
|
|
* so check explicitly for the right codes here.
|
|
*/
|
|
if (kinfo->si_signo == SIGBUS &&
|
|
(kinfo->si_code == BUS_MCEERR_AR ||
|
|
kinfo->si_code == BUS_MCEERR_AO))
|
|
err |= __put_user((short) kinfo->si_addr_lsb,
|
|
&uinfo->ssi_addr_lsb);
|
|
#endif
|
|
break;
|
|
case SIL_CHLD:
|
|
err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
|
|
err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
|
|
err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
|
|
err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
|
|
err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
|
|
break;
|
|
case SIL_RT:
|
|
default:
|
|
/*
|
|
* This case catches also the signals queued by sigqueue().
|
|
*/
|
|
err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
|
|
err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
|
|
err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
|
|
err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
|
|
break;
|
|
}
|
|
|
|
return err ? -EFAULT: sizeof(*uinfo);
|
|
}
|
|
|
|
static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
|
|
int nonblock)
|
|
{
|
|
ssize_t ret;
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
ret = dequeue_signal(current, &ctx->sigmask, info);
|
|
switch (ret) {
|
|
case 0:
|
|
if (!nonblock)
|
|
break;
|
|
ret = -EAGAIN;
|
|
default:
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
return ret;
|
|
}
|
|
|
|
add_wait_queue(¤t->sighand->signalfd_wqh, &wait);
|
|
for (;;) {
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
ret = dequeue_signal(current, &ctx->sigmask, info);
|
|
if (ret != 0)
|
|
break;
|
|
if (signal_pending(current)) {
|
|
ret = -ERESTARTSYS;
|
|
break;
|
|
}
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
schedule();
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
}
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
|
|
remove_wait_queue(¤t->sighand->signalfd_wqh, &wait);
|
|
__set_current_state(TASK_RUNNING);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
|
|
* error code. The "count" parameter must be at least the size of a
|
|
* "struct signalfd_siginfo".
|
|
*/
|
|
static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
|
|
loff_t *ppos)
|
|
{
|
|
struct signalfd_ctx *ctx = file->private_data;
|
|
struct signalfd_siginfo __user *siginfo;
|
|
int nonblock = file->f_flags & O_NONBLOCK;
|
|
ssize_t ret, total = 0;
|
|
siginfo_t info;
|
|
|
|
count /= sizeof(struct signalfd_siginfo);
|
|
if (!count)
|
|
return -EINVAL;
|
|
|
|
siginfo = (struct signalfd_siginfo __user *) buf;
|
|
do {
|
|
ret = signalfd_dequeue(ctx, &info, nonblock);
|
|
if (unlikely(ret <= 0))
|
|
break;
|
|
ret = signalfd_copyinfo(siginfo, &info);
|
|
if (ret < 0)
|
|
break;
|
|
siginfo++;
|
|
total += ret;
|
|
nonblock = 1;
|
|
} while (--count);
|
|
|
|
return total ? total: ret;
|
|
}
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
static void signalfd_show_fdinfo(struct seq_file *m, struct file *f)
|
|
{
|
|
struct signalfd_ctx *ctx = f->private_data;
|
|
sigset_t sigmask;
|
|
|
|
sigmask = ctx->sigmask;
|
|
signotset(&sigmask);
|
|
render_sigset_t(m, "sigmask:\t", &sigmask);
|
|
}
|
|
#endif
|
|
|
|
static const struct file_operations signalfd_fops = {
|
|
#ifdef CONFIG_PROC_FS
|
|
.show_fdinfo = signalfd_show_fdinfo,
|
|
#endif
|
|
.release = signalfd_release,
|
|
.poll = signalfd_poll,
|
|
.read = signalfd_read,
|
|
.llseek = noop_llseek,
|
|
};
|
|
|
|
SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
|
|
size_t, sizemask, int, flags)
|
|
{
|
|
sigset_t sigmask;
|
|
struct signalfd_ctx *ctx;
|
|
|
|
/* Check the SFD_* constants for consistency. */
|
|
BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
|
|
BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
|
|
|
|
if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
|
|
return -EINVAL;
|
|
|
|
if (sizemask != sizeof(sigset_t) ||
|
|
copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
|
|
return -EINVAL;
|
|
sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
|
|
signotset(&sigmask);
|
|
|
|
if (ufd == -1) {
|
|
ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
|
|
if (!ctx)
|
|
return -ENOMEM;
|
|
|
|
ctx->sigmask = sigmask;
|
|
|
|
/*
|
|
* When we call this, the initialization must be complete, since
|
|
* anon_inode_getfd() will install the fd.
|
|
*/
|
|
ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
|
|
O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
|
|
if (ufd < 0)
|
|
kfree(ctx);
|
|
} else {
|
|
struct fd f = fdget(ufd);
|
|
if (!f.file)
|
|
return -EBADF;
|
|
ctx = f.file->private_data;
|
|
if (f.file->f_op != &signalfd_fops) {
|
|
fdput(f);
|
|
return -EINVAL;
|
|
}
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
ctx->sigmask = sigmask;
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
|
|
wake_up(¤t->sighand->signalfd_wqh);
|
|
fdput(f);
|
|
}
|
|
|
|
return ufd;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
|
|
size_t, sizemask)
|
|
{
|
|
return sys_signalfd4(ufd, user_mask, sizemask, 0);
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd,
|
|
const compat_sigset_t __user *,sigmask,
|
|
compat_size_t, sigsetsize,
|
|
int, flags)
|
|
{
|
|
sigset_t tmp;
|
|
sigset_t __user *ksigmask;
|
|
|
|
if (sigsetsize != sizeof(compat_sigset_t))
|
|
return -EINVAL;
|
|
if (get_compat_sigset(&tmp, sigmask))
|
|
return -EFAULT;
|
|
ksigmask = compat_alloc_user_space(sizeof(sigset_t));
|
|
if (copy_to_user(ksigmask, &tmp, sizeof(sigset_t)))
|
|
return -EFAULT;
|
|
|
|
return sys_signalfd4(ufd, ksigmask, sizeof(sigset_t), flags);
|
|
}
|
|
|
|
COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd,
|
|
const compat_sigset_t __user *,sigmask,
|
|
compat_size_t, sigsetsize)
|
|
{
|
|
return compat_sys_signalfd4(ufd, sigmask, sigsetsize, 0);
|
|
}
|
|
#endif
|