diff options
Diffstat (limited to '')
| -rw-r--r-- | fs/signalfd.c | 354 |
1 files changed, 354 insertions, 0 deletions
diff --git a/fs/signalfd.c b/fs/signalfd.c new file mode 100644 index 000000000..e20d1484c --- /dev/null +++ b/fs/signalfd.c @@ -0,0 +1,354 @@ +// 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) +{ + wake_up_pollfree(&sighand->signalfd_wqh); +} + +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, + kernel_siginfo_t const *kinfo) +{ + struct signalfd_siginfo new; + + BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128); + + /* + * Unused members should be zero ... + */ + memset(&new, 0, sizeof(new)); + + /* + * If you change siginfo_t structure, please be sure + * this code is fixed accordingly. + */ + new.ssi_signo = kinfo->si_signo; + new.ssi_errno = kinfo->si_errno; + new.ssi_code = kinfo->si_code; + switch (siginfo_layout(kinfo->si_signo, kinfo->si_code)) { + case SIL_KILL: + new.ssi_pid = kinfo->si_pid; + new.ssi_uid = kinfo->si_uid; + break; + case SIL_TIMER: + new.ssi_tid = kinfo->si_tid; + new.ssi_overrun = kinfo->si_overrun; + new.ssi_ptr = (long) kinfo->si_ptr; + new.ssi_int = kinfo->si_int; + break; + case SIL_POLL: + new.ssi_band = kinfo->si_band; + new.ssi_fd = kinfo->si_fd; + break; + case SIL_FAULT_BNDERR: + case SIL_FAULT_PKUERR: + case SIL_FAULT_PERF_EVENT: + /* + * Fall through to the SIL_FAULT case. SIL_FAULT_BNDERR, + * SIL_FAULT_PKUERR, and SIL_FAULT_PERF_EVENT are only + * generated by faults that deliver them synchronously to + * userspace. In case someone injects one of these signals + * and signalfd catches it treat it as SIL_FAULT. + */ + case SIL_FAULT: + new.ssi_addr = (long) kinfo->si_addr; + break; + case SIL_FAULT_TRAPNO: + new.ssi_addr = (long) kinfo->si_addr; + new.ssi_trapno = kinfo->si_trapno; + break; + case SIL_FAULT_MCEERR: + new.ssi_addr = (long) kinfo->si_addr; + new.ssi_addr_lsb = (short) kinfo->si_addr_lsb; + break; + case SIL_CHLD: + new.ssi_pid = kinfo->si_pid; + new.ssi_uid = kinfo->si_uid; + new.ssi_status = kinfo->si_status; + new.ssi_utime = kinfo->si_utime; + new.ssi_stime = kinfo->si_stime; + break; + case SIL_RT: + /* + * This case catches also the signals queued by sigqueue(). + */ + new.ssi_pid = kinfo->si_pid; + new.ssi_uid = kinfo->si_uid; + new.ssi_ptr = (long) kinfo->si_ptr; + new.ssi_int = kinfo->si_int; + break; + case SIL_SYS: + new.ssi_call_addr = (long) kinfo->si_call_addr; + new.ssi_syscall = kinfo->si_syscall; + new.ssi_arch = kinfo->si_arch; + break; + } + + if (copy_to_user(uinfo, &new, sizeof(struct signalfd_siginfo))) + return -EFAULT; + + return sizeof(*uinfo); +} + +static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, kernel_siginfo_t *info, + int nonblock) +{ + enum pid_type type; + ssize_t ret; + DECLARE_WAITQUEUE(wait, current); + + spin_lock_irq(¤t->sighand->siglock); + ret = dequeue_signal(current, &ctx->sigmask, info, &type); + switch (ret) { + case 0: + if (!nonblock) + break; + ret = -EAGAIN; + fallthrough; + 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, &type); + 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; + kernel_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, +}; + +static int do_signalfd4(int ufd, sigset_t *mask, int flags) +{ + 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; + + sigdelsetmask(mask, sigmask(SIGKILL) | sigmask(SIGSTOP)); + signotset(mask); + + if (ufd == -1) { + ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); + if (!ctx) + return -ENOMEM; + + ctx->sigmask = *mask; + + /* + * 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 = *mask; + spin_unlock_irq(¤t->sighand->siglock); + + wake_up(¤t->sighand->signalfd_wqh); + fdput(f); + } + + return ufd; +} + +SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask, + size_t, sizemask, int, flags) +{ + sigset_t mask; + + if (sizemask != sizeof(sigset_t)) + return -EINVAL; + if (copy_from_user(&mask, user_mask, sizeof(mask))) + return -EFAULT; + return do_signalfd4(ufd, &mask, flags); +} + +SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask, + size_t, sizemask) +{ + sigset_t mask; + + if (sizemask != sizeof(sigset_t)) + return -EINVAL; + if (copy_from_user(&mask, user_mask, sizeof(mask))) + return -EFAULT; + return do_signalfd4(ufd, &mask, 0); +} + +#ifdef CONFIG_COMPAT +static long do_compat_signalfd4(int ufd, + const compat_sigset_t __user *user_mask, + compat_size_t sigsetsize, int flags) +{ + sigset_t mask; + + if (sigsetsize != sizeof(compat_sigset_t)) + return -EINVAL; + if (get_compat_sigset(&mask, user_mask)) + return -EFAULT; + return do_signalfd4(ufd, &mask, flags); +} + +COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd, + const compat_sigset_t __user *, user_mask, + compat_size_t, sigsetsize, + int, flags) +{ + return do_compat_signalfd4(ufd, user_mask, sigsetsize, flags); +} + +COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd, + const compat_sigset_t __user *, user_mask, + compat_size_t, sigsetsize) +{ + return do_compat_signalfd4(ufd, user_mask, sigsetsize, 0); +} +#endif |