Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1043 insertions, 0 deletions

diff --git a/fs/fcntl.c b/fs/fcntl.c
new file mode 100644
index 0000000000..e871009f6c
--- /dev/null
+++ b/fs/fcntl.c
@@ -0,0 +1,1043 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/fcntl.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#include <linux/syscalls.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/sched/task.h>
+#include <linux/fs.h>
+#include <linux/filelock.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/capability.h>
+#include <linux/dnotify.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/pipe_fs_i.h>
+#include <linux/security.h>
+#include <linux/ptrace.h>
+#include <linux/signal.h>
+#include <linux/rcupdate.h>
+#include <linux/pid_namespace.h>
+#include <linux/user_namespace.h>
+#include <linux/memfd.h>
+#include <linux/compat.h>
+#include <linux/mount.h>
+
+#include <linux/poll.h>
+#include <asm/siginfo.h>
+#include <linux/uaccess.h>
+
+#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
+
+static int setfl(int fd, struct file * filp, unsigned int arg)
+{
+	struct inode * inode = file_inode(filp);
+	int error = 0;
+
+	/*
+	 * O_APPEND cannot be cleared if the file is marked as append-only
+	 * and the file is open for write.
+	 */
+	if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
+		return -EPERM;
+
+	/* O_NOATIME can only be set by the owner or superuser */
+	if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
+		if (!inode_owner_or_capable(file_mnt_idmap(filp), inode))
+			return -EPERM;
+
+	/* required for strict SunOS emulation */
+	if (O_NONBLOCK != O_NDELAY)
+	       if (arg & O_NDELAY)
+		   arg |= O_NONBLOCK;
+
+	/* Pipe packetized mode is controlled by O_DIRECT flag */
+	if (!S_ISFIFO(inode->i_mode) &&
+	    (arg & O_DIRECT) &&
+	    !(filp->f_mode & FMODE_CAN_ODIRECT))
+		return -EINVAL;
+
+	if (filp->f_op->check_flags)
+		error = filp->f_op->check_flags(arg);
+	if (error)
+		return error;
+
+	/*
+	 * ->fasync() is responsible for setting the FASYNC bit.
+	 */
+	if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) {
+		error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
+		if (error < 0)
+			goto out;
+		if (error > 0)
+			error = 0;
+	}
+	spin_lock(&filp->f_lock);
+	filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
+	filp->f_iocb_flags = iocb_flags(filp);
+	spin_unlock(&filp->f_lock);
+
+ out:
+	return error;
+}
+
+static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
+                     int force)
+{
+	write_lock_irq(&filp->f_owner.lock);
+	if (force || !filp->f_owner.pid) {
+		put_pid(filp->f_owner.pid);
+		filp->f_owner.pid = get_pid(pid);
+		filp->f_owner.pid_type = type;
+
+		if (pid) {
+			const struct cred *cred = current_cred();
+			filp->f_owner.uid = cred->uid;
+			filp->f_owner.euid = cred->euid;
+		}
+	}
+	write_unlock_irq(&filp->f_owner.lock);
+}
+
+void __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
+		int force)
+{
+	security_file_set_fowner(filp);
+	f_modown(filp, pid, type, force);
+}
+EXPORT_SYMBOL(__f_setown);
+
+int f_setown(struct file *filp, int who, int force)
+{
+	enum pid_type type;
+	struct pid *pid = NULL;
+	int ret = 0;
+
+	type = PIDTYPE_TGID;
+	if (who < 0) {
+		/* avoid overflow below */
+		if (who == INT_MIN)
+			return -EINVAL;
+
+		type = PIDTYPE_PGID;
+		who = -who;
+	}
+
+	rcu_read_lock();
+	if (who) {
+		pid = find_vpid(who);
+		if (!pid)
+			ret = -ESRCH;
+	}
+
+	if (!ret)
+		__f_setown(filp, pid, type, force);
+	rcu_read_unlock();
+
+	return ret;
+}
+EXPORT_SYMBOL(f_setown);
+
+void f_delown(struct file *filp)
+{
+	f_modown(filp, NULL, PIDTYPE_TGID, 1);
+}
+
+pid_t f_getown(struct file *filp)
+{
+	pid_t pid = 0;
+
+	read_lock_irq(&filp->f_owner.lock);
+	rcu_read_lock();
+	if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type)) {
+		pid = pid_vnr(filp->f_owner.pid);
+		if (filp->f_owner.pid_type == PIDTYPE_PGID)
+			pid = -pid;
+	}
+	rcu_read_unlock();
+	read_unlock_irq(&filp->f_owner.lock);
+	return pid;
+}
+
+static int f_setown_ex(struct file *filp, unsigned long arg)
+{
+	struct f_owner_ex __user *owner_p = (void __user *)arg;
+	struct f_owner_ex owner;
+	struct pid *pid;
+	int type;
+	int ret;
+
+	ret = copy_from_user(&owner, owner_p, sizeof(owner));
+	if (ret)
+		return -EFAULT;
+
+	switch (owner.type) {
+	case F_OWNER_TID:
+		type = PIDTYPE_PID;
+		break;
+
+	case F_OWNER_PID:
+		type = PIDTYPE_TGID;
+		break;
+
+	case F_OWNER_PGRP:
+		type = PIDTYPE_PGID;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	rcu_read_lock();
+	pid = find_vpid(owner.pid);
+	if (owner.pid && !pid)
+		ret = -ESRCH;
+	else
+		 __f_setown(filp, pid, type, 1);
+	rcu_read_unlock();
+
+	return ret;
+}
+
+static int f_getown_ex(struct file *filp, unsigned long arg)
+{
+	struct f_owner_ex __user *owner_p = (void __user *)arg;
+	struct f_owner_ex owner = {};
+	int ret = 0;
+
+	read_lock_irq(&filp->f_owner.lock);
+	rcu_read_lock();
+	if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type))
+		owner.pid = pid_vnr(filp->f_owner.pid);
+	rcu_read_unlock();
+	switch (filp->f_owner.pid_type) {
+	case PIDTYPE_PID:
+		owner.type = F_OWNER_TID;
+		break;
+
+	case PIDTYPE_TGID:
+		owner.type = F_OWNER_PID;
+		break;
+
+	case PIDTYPE_PGID:
+		owner.type = F_OWNER_PGRP;
+		break;
+
+	default:
+		WARN_ON(1);
+		ret = -EINVAL;
+		break;
+	}
+	read_unlock_irq(&filp->f_owner.lock);
+
+	if (!ret) {
+		ret = copy_to_user(owner_p, &owner, sizeof(owner));
+		if (ret)
+			ret = -EFAULT;
+	}
+	return ret;
+}
+
+#ifdef CONFIG_CHECKPOINT_RESTORE
+static int f_getowner_uids(struct file *filp, unsigned long arg)
+{
+	struct user_namespace *user_ns = current_user_ns();
+	uid_t __user *dst = (void __user *)arg;
+	uid_t src[2];
+	int err;
+
+	read_lock_irq(&filp->f_owner.lock);
+	src[0] = from_kuid(user_ns, filp->f_owner.uid);
+	src[1] = from_kuid(user_ns, filp->f_owner.euid);
+	read_unlock_irq(&filp->f_owner.lock);
+
+	err  = put_user(src[0], &dst[0]);
+	err |= put_user(src[1], &dst[1]);
+
+	return err;
+}
+#else
+static int f_getowner_uids(struct file *filp, unsigned long arg)
+{
+	return -EINVAL;
+}
+#endif
+
+static bool rw_hint_valid(enum rw_hint hint)
+{
+	switch (hint) {
+	case RWH_WRITE_LIFE_NOT_SET:
+	case RWH_WRITE_LIFE_NONE:
+	case RWH_WRITE_LIFE_SHORT:
+	case RWH_WRITE_LIFE_MEDIUM:
+	case RWH_WRITE_LIFE_LONG:
+	case RWH_WRITE_LIFE_EXTREME:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static long fcntl_rw_hint(struct file *file, unsigned int cmd,
+			  unsigned long arg)
+{
+	struct inode *inode = file_inode(file);
+	u64 __user *argp = (u64 __user *)arg;
+	enum rw_hint hint;
+	u64 h;
+
+	switch (cmd) {
+	case F_GET_RW_HINT:
+		h = inode->i_write_hint;
+		if (copy_to_user(argp, &h, sizeof(*argp)))
+			return -EFAULT;
+		return 0;
+	case F_SET_RW_HINT:
+		if (copy_from_user(&h, argp, sizeof(h)))
+			return -EFAULT;
+		hint = (enum rw_hint) h;
+		if (!rw_hint_valid(hint))
+			return -EINVAL;
+
+		inode_lock(inode);
+		inode->i_write_hint = hint;
+		inode_unlock(inode);
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
+		struct file *filp)
+{
+	void __user *argp = (void __user *)arg;
+	int argi = (int)arg;
+	struct flock flock;
+	long err = -EINVAL;
+
+	switch (cmd) {
+	case F_DUPFD:
+		err = f_dupfd(argi, filp, 0);
+		break;
+	case F_DUPFD_CLOEXEC:
+		err = f_dupfd(argi, filp, O_CLOEXEC);
+		break;
+	case F_GETFD:
+		err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
+		break;
+	case F_SETFD:
+		err = 0;
+		set_close_on_exec(fd, argi & FD_CLOEXEC);
+		break;
+	case F_GETFL:
+		err = filp->f_flags;
+		break;
+	case F_SETFL:
+		err = setfl(fd, filp, argi);
+		break;
+#if BITS_PER_LONG != 32
+	/* 32-bit arches must use fcntl64() */
+	case F_OFD_GETLK:
+#endif
+	case F_GETLK:
+		if (copy_from_user(&flock, argp, sizeof(flock)))
+			return -EFAULT;
+		err = fcntl_getlk(filp, cmd, &flock);
+		if (!err && copy_to_user(argp, &flock, sizeof(flock)))
+			return -EFAULT;
+		break;
+#if BITS_PER_LONG != 32
+	/* 32-bit arches must use fcntl64() */
+	case F_OFD_SETLK:
+	case F_OFD_SETLKW:
+		fallthrough;
+#endif
+	case F_SETLK:
+	case F_SETLKW:
+		if (copy_from_user(&flock, argp, sizeof(flock)))
+			return -EFAULT;
+		err = fcntl_setlk(fd, filp, cmd, &flock);
+		break;
+	case F_GETOWN:
+		/*
+		 * XXX If f_owner is a process group, the
+		 * negative return value will get converted
+		 * into an error.  Oops.  If we keep the
+		 * current syscall conventions, the only way
+		 * to fix this will be in libc.
+		 */
+		err = f_getown(filp);
+		force_successful_syscall_return();
+		break;
+	case F_SETOWN:
+		err = f_setown(filp, argi, 1);
+		break;
+	case F_GETOWN_EX:
+		err = f_getown_ex(filp, arg);
+		break;
+	case F_SETOWN_EX:
+		err = f_setown_ex(filp, arg);
+		break;
+	case F_GETOWNER_UIDS:
+		err = f_getowner_uids(filp, arg);
+		break;
+	case F_GETSIG:
+		err = filp->f_owner.signum;
+		break;
+	case F_SETSIG:
+		/* arg == 0 restores default behaviour. */
+		if (!valid_signal(argi)) {
+			break;
+		}
+		err = 0;
+		filp->f_owner.signum = argi;
+		break;
+	case F_GETLEASE:
+		err = fcntl_getlease(filp);
+		break;
+	case F_SETLEASE:
+		err = fcntl_setlease(fd, filp, argi);
+		break;
+	case F_NOTIFY:
+		err = fcntl_dirnotify(fd, filp, argi);
+		break;
+	case F_SETPIPE_SZ:
+	case F_GETPIPE_SZ:
+		err = pipe_fcntl(filp, cmd, argi);
+		break;
+	case F_ADD_SEALS:
+	case F_GET_SEALS:
+		err = memfd_fcntl(filp, cmd, argi);
+		break;
+	case F_GET_RW_HINT:
+	case F_SET_RW_HINT:
+		err = fcntl_rw_hint(filp, cmd, arg);
+		break;
+	default:
+		break;
+	}
+	return err;
+}
+
+static int check_fcntl_cmd(unsigned cmd)
+{
+	switch (cmd) {
+	case F_DUPFD:
+	case F_DUPFD_CLOEXEC:
+	case F_GETFD:
+	case F_SETFD:
+	case F_GETFL:
+		return 1;
+	}
+	return 0;
+}
+
+SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
+{	
+	struct fd f = fdget_raw(fd);
+	long err = -EBADF;
+
+	if (!f.file)
+		goto out;
+
+	if (unlikely(f.file->f_mode & FMODE_PATH)) {
+		if (!check_fcntl_cmd(cmd))
+			goto out1;
+	}
+
+	err = security_file_fcntl(f.file, cmd, arg);
+	if (!err)
+		err = do_fcntl(fd, cmd, arg, f.file);
+
+out1:
+ 	fdput(f);
+out:
+	return err;
+}
+
+#if BITS_PER_LONG == 32
+SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
+		unsigned long, arg)
+{	
+	void __user *argp = (void __user *)arg;
+	struct fd f = fdget_raw(fd);
+	struct flock64 flock;
+	long err = -EBADF;
+
+	if (!f.file)
+		goto out;
+
+	if (unlikely(f.file->f_mode & FMODE_PATH)) {
+		if (!check_fcntl_cmd(cmd))
+			goto out1;
+	}
+
+	err = security_file_fcntl(f.file, cmd, arg);
+	if (err)
+		goto out1;
+	
+	switch (cmd) {
+	case F_GETLK64:
+	case F_OFD_GETLK:
+		err = -EFAULT;
+		if (copy_from_user(&flock, argp, sizeof(flock)))
+			break;
+		err = fcntl_getlk64(f.file, cmd, &flock);
+		if (!err && copy_to_user(argp, &flock, sizeof(flock)))
+			err = -EFAULT;
+		break;
+	case F_SETLK64:
+	case F_SETLKW64:
+	case F_OFD_SETLK:
+	case F_OFD_SETLKW:
+		err = -EFAULT;
+		if (copy_from_user(&flock, argp, sizeof(flock)))
+			break;
+		err = fcntl_setlk64(fd, f.file, cmd, &flock);
+		break;
+	default:
+		err = do_fcntl(fd, cmd, arg, f.file);
+		break;
+	}
+out1:
+	fdput(f);
+out:
+	return err;
+}
+#endif
+
+#ifdef CONFIG_COMPAT
+/* careful - don't use anywhere else */
+#define copy_flock_fields(dst, src)		\
+	(dst)->l_type = (src)->l_type;		\
+	(dst)->l_whence = (src)->l_whence;	\
+	(dst)->l_start = (src)->l_start;	\
+	(dst)->l_len = (src)->l_len;		\
+	(dst)->l_pid = (src)->l_pid;
+
+static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl)
+{
+	struct compat_flock fl;
+
+	if (copy_from_user(&fl, ufl, sizeof(struct compat_flock)))
+		return -EFAULT;
+	copy_flock_fields(kfl, &fl);
+	return 0;
+}
+
+static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl)
+{
+	struct compat_flock64 fl;
+
+	if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64)))
+		return -EFAULT;
+	copy_flock_fields(kfl, &fl);
+	return 0;
+}
+
+static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl)
+{
+	struct compat_flock fl;
+
+	memset(&fl, 0, sizeof(struct compat_flock));
+	copy_flock_fields(&fl, kfl);
+	if (copy_to_user(ufl, &fl, sizeof(struct compat_flock)))
+		return -EFAULT;
+	return 0;
+}
+
+static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl)
+{
+	struct compat_flock64 fl;
+
+	BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start));
+	BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len));
+
+	memset(&fl, 0, sizeof(struct compat_flock64));
+	copy_flock_fields(&fl, kfl);
+	if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64)))
+		return -EFAULT;
+	return 0;
+}
+#undef copy_flock_fields
+
+static unsigned int
+convert_fcntl_cmd(unsigned int cmd)
+{
+	switch (cmd) {
+	case F_GETLK64:
+		return F_GETLK;
+	case F_SETLK64:
+		return F_SETLK;
+	case F_SETLKW64:
+		return F_SETLKW;
+	}
+
+	return cmd;
+}
+
+/*
+ * GETLK was successful and we need to return the data, but it needs to fit in
+ * the compat structure.
+ * l_start shouldn't be too big, unless the original start + end is greater than
+ * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return
+ * -EOVERFLOW in that case.  l_len could be too big, in which case we just
+ * truncate it, and only allow the app to see that part of the conflicting lock
+ * that might make sense to it anyway
+ */
+static int fixup_compat_flock(struct flock *flock)
+{
+	if (flock->l_start > COMPAT_OFF_T_MAX)
+		return -EOVERFLOW;
+	if (flock->l_len > COMPAT_OFF_T_MAX)
+		flock->l_len = COMPAT_OFF_T_MAX;
+	return 0;
+}
+
+static long do_compat_fcntl64(unsigned int fd, unsigned int cmd,
+			     compat_ulong_t arg)
+{
+	struct fd f = fdget_raw(fd);
+	struct flock flock;
+	long err = -EBADF;
+
+	if (!f.file)
+		return err;
+
+	if (unlikely(f.file->f_mode & FMODE_PATH)) {
+		if (!check_fcntl_cmd(cmd))
+			goto out_put;
+	}
+
+	err = security_file_fcntl(f.file, cmd, arg);
+	if (err)
+		goto out_put;
+
+	switch (cmd) {
+	case F_GETLK:
+		err = get_compat_flock(&flock, compat_ptr(arg));
+		if (err)
+			break;
+		err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock);
+		if (err)
+			break;
+		err = fixup_compat_flock(&flock);
+		if (!err)
+			err = put_compat_flock(&flock, compat_ptr(arg));
+		break;
+	case F_GETLK64:
+	case F_OFD_GETLK:
+		err = get_compat_flock64(&flock, compat_ptr(arg));
+		if (err)
+			break;
+		err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock);
+		if (!err)
+			err = put_compat_flock64(&flock, compat_ptr(arg));
+		break;
+	case F_SETLK:
+	case F_SETLKW:
+		err = get_compat_flock(&flock, compat_ptr(arg));
+		if (err)
+			break;
+		err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock);
+		break;
+	case F_SETLK64:
+	case F_SETLKW64:
+	case F_OFD_SETLK:
+	case F_OFD_SETLKW:
+		err = get_compat_flock64(&flock, compat_ptr(arg));
+		if (err)
+			break;
+		err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock);
+		break;
+	default:
+		err = do_fcntl(fd, cmd, arg, f.file);
+		break;
+	}
+out_put:
+	fdput(f);
+	return err;
+}
+
+COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
+		       compat_ulong_t, arg)
+{
+	return do_compat_fcntl64(fd, cmd, arg);
+}
+
+COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd,
+		       compat_ulong_t, arg)
+{
+	switch (cmd) {
+	case F_GETLK64:
+	case F_SETLK64:
+	case F_SETLKW64:
+	case F_OFD_GETLK:
+	case F_OFD_SETLK:
+	case F_OFD_SETLKW:
+		return -EINVAL;
+	}
+	return do_compat_fcntl64(fd, cmd, arg);
+}
+#endif
+
+/* Table to convert sigio signal codes into poll band bitmaps */
+
+static const __poll_t band_table[NSIGPOLL] = {
+	EPOLLIN | EPOLLRDNORM,			/* POLL_IN */
+	EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND,	/* POLL_OUT */
+	EPOLLIN | EPOLLRDNORM | EPOLLMSG,		/* POLL_MSG */
+	EPOLLERR,				/* POLL_ERR */
+	EPOLLPRI | EPOLLRDBAND,			/* POLL_PRI */
+	EPOLLHUP | EPOLLERR			/* POLL_HUP */
+};
+
+static inline int sigio_perm(struct task_struct *p,
+                             struct fown_struct *fown, int sig)
+{
+	const struct cred *cred;
+	int ret;
+
+	rcu_read_lock();
+	cred = __task_cred(p);
+	ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
+		uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
+		uid_eq(fown->uid,  cred->suid) || uid_eq(fown->uid,  cred->uid)) &&
+	       !security_file_send_sigiotask(p, fown, sig));
+	rcu_read_unlock();
+	return ret;
+}
+
+static void send_sigio_to_task(struct task_struct *p,
+			       struct fown_struct *fown,
+			       int fd, int reason, enum pid_type type)
+{
+	/*
+	 * F_SETSIG can change ->signum lockless in parallel, make
+	 * sure we read it once and use the same value throughout.
+	 */
+	int signum = READ_ONCE(fown->signum);
+
+	if (!sigio_perm(p, fown, signum))
+		return;
+
+	switch (signum) {
+		default: {
+			kernel_siginfo_t si;
+
+			/* Queue a rt signal with the appropriate fd as its
+			   value.  We use SI_SIGIO as the source, not 
+			   SI_KERNEL, since kernel signals always get 
+			   delivered even if we can't queue.  Failure to
+			   queue in this case _should_ be reported; we fall
+			   back to SIGIO in that case. --sct */
+			clear_siginfo(&si);
+			si.si_signo = signum;
+			si.si_errno = 0;
+		        si.si_code  = reason;
+			/*
+			 * Posix definies POLL_IN and friends to be signal
+			 * specific si_codes for SIG_POLL.  Linux extended
+			 * these si_codes to other signals in a way that is
+			 * ambiguous if other signals also have signal
+			 * specific si_codes.  In that case use SI_SIGIO instead
+			 * to remove the ambiguity.
+			 */
+			if ((signum != SIGPOLL) && sig_specific_sicodes(signum))
+				si.si_code = SI_SIGIO;
+
+			/* Make sure we are called with one of the POLL_*
+			   reasons, otherwise we could leak kernel stack into
+			   userspace.  */
+			BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL));
+			if (reason - POLL_IN >= NSIGPOLL)
+				si.si_band  = ~0L;
+			else
+				si.si_band = mangle_poll(band_table[reason - POLL_IN]);
+			si.si_fd    = fd;
+			if (!do_send_sig_info(signum, &si, p, type))
+				break;
+		}
+			fallthrough;	/* fall back on the old plain SIGIO signal */
+		case 0:
+			do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type);
+	}
+}
+
+void send_sigio(struct fown_struct *fown, int fd, int band)
+{
+	struct task_struct *p;
+	enum pid_type type;
+	unsigned long flags;
+	struct pid *pid;
+	
+	read_lock_irqsave(&fown->lock, flags);
+
+	type = fown->pid_type;
+	pid = fown->pid;
+	if (!pid)
+		goto out_unlock_fown;
+
+	if (type <= PIDTYPE_TGID) {
+		rcu_read_lock();
+		p = pid_task(pid, PIDTYPE_PID);
+		if (p)
+			send_sigio_to_task(p, fown, fd, band, type);
+		rcu_read_unlock();
+	} else {
+		read_lock(&tasklist_lock);
+		do_each_pid_task(pid, type, p) {
+			send_sigio_to_task(p, fown, fd, band, type);
+		} while_each_pid_task(pid, type, p);
+		read_unlock(&tasklist_lock);
+	}
+ out_unlock_fown:
+	read_unlock_irqrestore(&fown->lock, flags);
+}
+
+static void send_sigurg_to_task(struct task_struct *p,
+				struct fown_struct *fown, enum pid_type type)
+{
+	if (sigio_perm(p, fown, SIGURG))
+		do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type);
+}
+
+int send_sigurg(struct fown_struct *fown)
+{
+	struct task_struct *p;
+	enum pid_type type;
+	struct pid *pid;
+	unsigned long flags;
+	int ret = 0;
+	
+	read_lock_irqsave(&fown->lock, flags);
+
+	type = fown->pid_type;
+	pid = fown->pid;
+	if (!pid)
+		goto out_unlock_fown;
+
+	ret = 1;
+
+	if (type <= PIDTYPE_TGID) {
+		rcu_read_lock();
+		p = pid_task(pid, PIDTYPE_PID);
+		if (p)
+			send_sigurg_to_task(p, fown, type);
+		rcu_read_unlock();
+	} else {
+		read_lock(&tasklist_lock);
+		do_each_pid_task(pid, type, p) {
+			send_sigurg_to_task(p, fown, type);
+		} while_each_pid_task(pid, type, p);
+		read_unlock(&tasklist_lock);
+	}
+ out_unlock_fown:
+	read_unlock_irqrestore(&fown->lock, flags);
+	return ret;
+}
+
+static DEFINE_SPINLOCK(fasync_lock);
+static struct kmem_cache *fasync_cache __read_mostly;
+
+static void fasync_free_rcu(struct rcu_head *head)
+{
+	kmem_cache_free(fasync_cache,
+			container_of(head, struct fasync_struct, fa_rcu));
+}
+
+/*
+ * Remove a fasync entry. If successfully removed, return
+ * positive and clear the FASYNC flag. If no entry exists,
+ * do nothing and return 0.
+ *
+ * NOTE! It is very important that the FASYNC flag always
+ * match the state "is the filp on a fasync list".
+ *
+ */
+int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
+{
+	struct fasync_struct *fa, **fp;
+	int result = 0;
+
+	spin_lock(&filp->f_lock);
+	spin_lock(&fasync_lock);
+	for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
+		if (fa->fa_file != filp)
+			continue;
+
+		write_lock_irq(&fa->fa_lock);
+		fa->fa_file = NULL;
+		write_unlock_irq(&fa->fa_lock);
+
+		*fp = fa->fa_next;
+		call_rcu(&fa->fa_rcu, fasync_free_rcu);
+		filp->f_flags &= ~FASYNC;
+		result = 1;
+		break;
+	}
+	spin_unlock(&fasync_lock);
+	spin_unlock(&filp->f_lock);
+	return result;
+}
+
+struct fasync_struct *fasync_alloc(void)
+{
+	return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
+}
+
+/*
+ * NOTE! This can be used only for unused fasync entries:
+ * entries that actually got inserted on the fasync list
+ * need to be released by rcu - see fasync_remove_entry.
+ */
+void fasync_free(struct fasync_struct *new)
+{
+	kmem_cache_free(fasync_cache, new);
+}
+
+/*
+ * Insert a new entry into the fasync list.  Return the pointer to the
+ * old one if we didn't use the new one.
+ *
+ * NOTE! It is very important that the FASYNC flag always
+ * match the state "is the filp on a fasync list".
+ */
+struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
+{
+        struct fasync_struct *fa, **fp;
+
+	spin_lock(&filp->f_lock);
+	spin_lock(&fasync_lock);
+	for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
+		if (fa->fa_file != filp)
+			continue;
+
+		write_lock_irq(&fa->fa_lock);
+		fa->fa_fd = fd;
+		write_unlock_irq(&fa->fa_lock);
+		goto out;
+	}
+
+	rwlock_init(&new->fa_lock);
+	new->magic = FASYNC_MAGIC;
+	new->fa_file = filp;
+	new->fa_fd = fd;
+	new->fa_next = *fapp;
+	rcu_assign_pointer(*fapp, new);
+	filp->f_flags |= FASYNC;
+
+out:
+	spin_unlock(&fasync_lock);
+	spin_unlock(&filp->f_lock);
+	return fa;
+}
+
+/*
+ * Add a fasync entry. Return negative on error, positive if
+ * added, and zero if did nothing but change an existing one.
+ */
+static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
+{
+	struct fasync_struct *new;
+
+	new = fasync_alloc();
+	if (!new)
+		return -ENOMEM;
+
+	/*
+	 * fasync_insert_entry() returns the old (update) entry if
+	 * it existed.
+	 *
+	 * So free the (unused) new entry and return 0 to let the
+	 * caller know that we didn't add any new fasync entries.
+	 */
+	if (fasync_insert_entry(fd, filp, fapp, new)) {
+		fasync_free(new);
+		return 0;
+	}
+
+	return 1;
+}
+
+/*
+ * fasync_helper() is used by almost all character device drivers
+ * to set up the fasync queue, and for regular files by the file
+ * lease code. It returns negative on error, 0 if it did no changes
+ * and positive if it added/deleted the entry.
+ */
+int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
+{
+	if (!on)
+		return fasync_remove_entry(filp, fapp);
+	return fasync_add_entry(fd, filp, fapp);
+}
+
+EXPORT_SYMBOL(fasync_helper);
+
+/*
+ * rcu_read_lock() is held
+ */
+static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
+{
+	while (fa) {
+		struct fown_struct *fown;
+		unsigned long flags;
+
+		if (fa->magic != FASYNC_MAGIC) {
+			printk(KERN_ERR "kill_fasync: bad magic number in "
+			       "fasync_struct!\n");
+			return;
+		}
+		read_lock_irqsave(&fa->fa_lock, flags);
+		if (fa->fa_file) {
+			fown = &fa->fa_file->f_owner;
+			/* Don't send SIGURG to processes which have not set a
+			   queued signum: SIGURG has its own default signalling
+			   mechanism. */
+			if (!(sig == SIGURG && fown->signum == 0))
+				send_sigio(fown, fa->fa_fd, band);
+		}
+		read_unlock_irqrestore(&fa->fa_lock, flags);
+		fa = rcu_dereference(fa->fa_next);
+	}
+}
+
+void kill_fasync(struct fasync_struct **fp, int sig, int band)
+{
+	/* First a quick test without locking: usually
+	 * the list is empty.
+	 */
+	if (*fp) {
+		rcu_read_lock();
+		kill_fasync_rcu(rcu_dereference(*fp), sig, band);
+		rcu_read_unlock();
+	}
+}
+EXPORT_SYMBOL(kill_fasync);
+
+static int __init fcntl_init(void)
+{
+	/*
+	 * Please add new bits here to ensure allocation uniqueness.
+	 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
+	 * is defined as O_NONBLOCK on some platforms and not on others.
+	 */
+	BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ !=
+		HWEIGHT32(
+			(VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) |
+			__FMODE_EXEC | __FMODE_NONOTIFY));
+
+	fasync_cache = kmem_cache_create("fasync_cache",
+					 sizeof(struct fasync_struct), 0,
+					 SLAB_PANIC | SLAB_ACCOUNT, NULL);
+	return 0;
+}
+
+module_init(fcntl_init)