| // 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, |
| 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: |
| /* |
| * Fall through to the SIL_FAULT case. Both SIL_FAULT_BNDERR |
| * and SIL_FAULT_PKUERR 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; |
| #ifdef __ARCH_SI_TRAPNO |
| new.ssi_trapno = kinfo->si_trapno; |
| #endif |
| break; |
| case SIL_FAULT_MCEERR: |
| new.ssi_addr = (long) kinfo->si_addr; |
| #ifdef __ARCH_SI_TRAPNO |
| new.ssi_trapno = kinfo->si_trapno; |
| #endif |
| 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, 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, |
| }; |
| |
| 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 |