Adding upstream version 5.10.209.upstream/5.10.209upstream

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

1 files changed, 1401 insertions, 0 deletions

diff --git a/fs/open.c b/fs/open.c
new file mode 100644
index 000000000..83f62cf14
--- /dev/null
+++ b/fs/open.c
@@ -0,0 +1,1401 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/fs/open.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/fsnotify.h>
+#include <linux/module.h>
+#include <linux/tty.h>
+#include <linux/namei.h>
+#include <linux/backing-dev.h>
+#include <linux/capability.h>
+#include <linux/securebits.h>
+#include <linux/security.h>
+#include <linux/mount.h>
+#include <linux/fcntl.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/fs.h>
+#include <linux/personality.h>
+#include <linux/pagemap.h>
+#include <linux/syscalls.h>
+#include <linux/rcupdate.h>
+#include <linux/audit.h>
+#include <linux/falloc.h>
+#include <linux/fs_struct.h>
+#include <linux/ima.h>
+#include <linux/dnotify.h>
+#include <linux/compat.h>
+
+#include "internal.h"
+
+int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
+	struct file *filp)
+{
+	int ret;
+	struct iattr newattrs;
+
+	/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
+	if (length < 0)
+		return -EINVAL;
+
+	newattrs.ia_size = length;
+	newattrs.ia_valid = ATTR_SIZE | time_attrs;
+	if (filp) {
+		newattrs.ia_file = filp;
+		newattrs.ia_valid |= ATTR_FILE;
+	}
+
+	/* Remove suid, sgid, and file capabilities on truncate too */
+	ret = dentry_needs_remove_privs(dentry);
+	if (ret < 0)
+		return ret;
+	if (ret)
+		newattrs.ia_valid |= ret | ATTR_FORCE;
+
+	inode_lock(dentry->d_inode);
+	/* Note any delegations or leases have already been broken: */
+	ret = notify_change(dentry, &newattrs, NULL);
+	inode_unlock(dentry->d_inode);
+	return ret;
+}
+
+long vfs_truncate(const struct path *path, loff_t length)
+{
+	struct inode *inode;
+	long error;
+
+	inode = path->dentry->d_inode;
+
+	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
+	if (S_ISDIR(inode->i_mode))
+		return -EISDIR;
+	if (!S_ISREG(inode->i_mode))
+		return -EINVAL;
+
+	error = mnt_want_write(path->mnt);
+	if (error)
+		goto out;
+
+	error = inode_permission(inode, MAY_WRITE);
+	if (error)
+		goto mnt_drop_write_and_out;
+
+	error = -EPERM;
+	if (IS_APPEND(inode))
+		goto mnt_drop_write_and_out;
+
+	error = get_write_access(inode);
+	if (error)
+		goto mnt_drop_write_and_out;
+
+	/*
+	 * Make sure that there are no leases.  get_write_access() protects
+	 * against the truncate racing with a lease-granting setlease().
+	 */
+	error = break_lease(inode, O_WRONLY);
+	if (error)
+		goto put_write_and_out;
+
+	error = locks_verify_truncate(inode, NULL, length);
+	if (!error)
+		error = security_path_truncate(path);
+	if (!error)
+		error = do_truncate(path->dentry, length, 0, NULL);
+
+put_write_and_out:
+	put_write_access(inode);
+mnt_drop_write_and_out:
+	mnt_drop_write(path->mnt);
+out:
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_truncate);
+
+long do_sys_truncate(const char __user *pathname, loff_t length)
+{
+	unsigned int lookup_flags = LOOKUP_FOLLOW;
+	struct path path;
+	int error;
+
+	if (length < 0)	/* sorry, but loff_t says... */
+		return -EINVAL;
+
+retry:
+	error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
+	if (!error) {
+		error = vfs_truncate(&path, length);
+		path_put(&path);
+	}
+	if (retry_estale(error, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
+	return error;
+}
+
+SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
+{
+	return do_sys_truncate(path, length);
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
+{
+	return do_sys_truncate(path, length);
+}
+#endif
+
+long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
+{
+	struct inode *inode;
+	struct dentry *dentry;
+	struct fd f;
+	int error;
+
+	error = -EINVAL;
+	if (length < 0)
+		goto out;
+	error = -EBADF;
+	f = fdget(fd);
+	if (!f.file)
+		goto out;
+
+	/* explicitly opened as large or we are on 64-bit box */
+	if (f.file->f_flags & O_LARGEFILE)
+		small = 0;
+
+	dentry = f.file->f_path.dentry;
+	inode = dentry->d_inode;
+	error = -EINVAL;
+	if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
+		goto out_putf;
+
+	error = -EINVAL;
+	/* Cannot ftruncate over 2^31 bytes without large file support */
+	if (small && length > MAX_NON_LFS)
+		goto out_putf;
+
+	error = -EPERM;
+	/* Check IS_APPEND on real upper inode */
+	if (IS_APPEND(file_inode(f.file)))
+		goto out_putf;
+
+	sb_start_write(inode->i_sb);
+	error = locks_verify_truncate(inode, f.file, length);
+	if (!error)
+		error = security_path_truncate(&f.file->f_path);
+	if (!error)
+		error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
+	sb_end_write(inode->i_sb);
+out_putf:
+	fdput(f);
+out:
+	return error;
+}
+
+SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
+{
+	return do_sys_ftruncate(fd, length, 1);
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
+{
+	return do_sys_ftruncate(fd, length, 1);
+}
+#endif
+
+/* LFS versions of truncate are only needed on 32 bit machines */
+#if BITS_PER_LONG == 32
+SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
+{
+	return do_sys_truncate(path, length);
+}
+
+SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
+{
+	return do_sys_ftruncate(fd, length, 0);
+}
+#endif /* BITS_PER_LONG == 32 */
+
+
+int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
+{
+	struct inode *inode = file_inode(file);
+	long ret;
+
+	if (offset < 0 || len <= 0)
+		return -EINVAL;
+
+	/* Return error if mode is not supported */
+	if (mode & ~FALLOC_FL_SUPPORTED_MASK)
+		return -EOPNOTSUPP;
+
+	/* Punch hole and zero range are mutually exclusive */
+	if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
+	    (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
+		return -EOPNOTSUPP;
+
+	/* Punch hole must have keep size set */
+	if ((mode & FALLOC_FL_PUNCH_HOLE) &&
+	    !(mode & FALLOC_FL_KEEP_SIZE))
+		return -EOPNOTSUPP;
+
+	/* Collapse range should only be used exclusively. */
+	if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
+	    (mode & ~FALLOC_FL_COLLAPSE_RANGE))
+		return -EINVAL;
+
+	/* Insert range should only be used exclusively. */
+	if ((mode & FALLOC_FL_INSERT_RANGE) &&
+	    (mode & ~FALLOC_FL_INSERT_RANGE))
+		return -EINVAL;
+
+	/* Unshare range should only be used with allocate mode. */
+	if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
+	    (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
+		return -EINVAL;
+
+	if (!(file->f_mode & FMODE_WRITE))
+		return -EBADF;
+
+	/*
+	 * We can only allow pure fallocate on append only files
+	 */
+	if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
+		return -EPERM;
+
+	if (IS_IMMUTABLE(inode))
+		return -EPERM;
+
+	/*
+	 * We cannot allow any fallocate operation on an active swapfile
+	 */
+	if (IS_SWAPFILE(inode))
+		return -ETXTBSY;
+
+	/*
+	 * Revalidate the write permissions, in case security policy has
+	 * changed since the files were opened.
+	 */
+	ret = security_file_permission(file, MAY_WRITE);
+	if (ret)
+		return ret;
+
+	if (S_ISFIFO(inode->i_mode))
+		return -ESPIPE;
+
+	if (S_ISDIR(inode->i_mode))
+		return -EISDIR;
+
+	if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
+		return -ENODEV;
+
+	/* Check for wrap through zero too */
+	if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
+		return -EFBIG;
+
+	if (!file->f_op->fallocate)
+		return -EOPNOTSUPP;
+
+	file_start_write(file);
+	ret = file->f_op->fallocate(file, mode, offset, len);
+
+	/*
+	 * Create inotify and fanotify events.
+	 *
+	 * To keep the logic simple always create events if fallocate succeeds.
+	 * This implies that events are even created if the file size remains
+	 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
+	 */
+	if (ret == 0)
+		fsnotify_modify(file);
+
+	file_end_write(file);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vfs_fallocate);
+
+int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
+{
+	struct fd f = fdget(fd);
+	int error = -EBADF;
+
+	if (f.file) {
+		error = vfs_fallocate(f.file, mode, offset, len);
+		fdput(f);
+	}
+	return error;
+}
+
+SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
+{
+	return ksys_fallocate(fd, mode, offset, len);
+}
+
+/*
+ * access() needs to use the real uid/gid, not the effective uid/gid.
+ * We do this by temporarily clearing all FS-related capabilities and
+ * switching the fsuid/fsgid around to the real ones.
+ */
+static const struct cred *access_override_creds(void)
+{
+	const struct cred *old_cred;
+	struct cred *override_cred;
+
+	override_cred = prepare_creds();
+	if (!override_cred)
+		return NULL;
+
+	override_cred->fsuid = override_cred->uid;
+	override_cred->fsgid = override_cred->gid;
+
+	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
+		/* Clear the capabilities if we switch to a non-root user */
+		kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
+		if (!uid_eq(override_cred->uid, root_uid))
+			cap_clear(override_cred->cap_effective);
+		else
+			override_cred->cap_effective =
+				override_cred->cap_permitted;
+	}
+
+	/*
+	 * The new set of credentials can *only* be used in
+	 * task-synchronous circumstances, and does not need
+	 * RCU freeing, unless somebody then takes a separate
+	 * reference to it.
+	 *
+	 * NOTE! This is _only_ true because this credential
+	 * is used purely for override_creds() that installs
+	 * it as the subjective cred. Other threads will be
+	 * accessing ->real_cred, not the subjective cred.
+	 *
+	 * If somebody _does_ make a copy of this (using the
+	 * 'get_current_cred()' function), that will clear the
+	 * non_rcu field, because now that other user may be
+	 * expecting RCU freeing. But normal thread-synchronous
+	 * cred accesses will keep things non-RCY.
+	 */
+	override_cred->non_rcu = 1;
+
+	old_cred = override_creds(override_cred);
+
+	/* override_cred() gets its own ref */
+	put_cred(override_cred);
+
+	return old_cred;
+}
+
+static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
+{
+	struct path path;
+	struct inode *inode;
+	int res;
+	unsigned int lookup_flags = LOOKUP_FOLLOW;
+	const struct cred *old_cred = NULL;
+
+	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
+		return -EINVAL;
+
+	if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
+		return -EINVAL;
+
+	if (flags & AT_SYMLINK_NOFOLLOW)
+		lookup_flags &= ~LOOKUP_FOLLOW;
+	if (flags & AT_EMPTY_PATH)
+		lookup_flags |= LOOKUP_EMPTY;
+
+	if (!(flags & AT_EACCESS)) {
+		old_cred = access_override_creds();
+		if (!old_cred)
+			return -ENOMEM;
+	}
+
+retry:
+	res = user_path_at(dfd, filename, lookup_flags, &path);
+	if (res)
+		goto out;
+
+	inode = d_backing_inode(path.dentry);
+
+	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
+		/*
+		 * MAY_EXEC on regular files is denied if the fs is mounted
+		 * with the "noexec" flag.
+		 */
+		res = -EACCES;
+		if (path_noexec(&path))
+			goto out_path_release;
+	}
+
+	res = inode_permission(inode, mode | MAY_ACCESS);
+	/* SuS v2 requires we report a read only fs too */
+	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
+		goto out_path_release;
+	/*
+	 * This is a rare case where using __mnt_is_readonly()
+	 * is OK without a mnt_want/drop_write() pair.  Since
+	 * no actual write to the fs is performed here, we do
+	 * not need to telegraph to that to anyone.
+	 *
+	 * By doing this, we accept that this access is
+	 * inherently racy and know that the fs may change
+	 * state before we even see this result.
+	 */
+	if (__mnt_is_readonly(path.mnt))
+		res = -EROFS;
+
+out_path_release:
+	path_put(&path);
+	if (retry_estale(res, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
+out:
+	if (old_cred)
+		revert_creds(old_cred);
+
+	return res;
+}
+
+SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
+{
+	return do_faccessat(dfd, filename, mode, 0);
+}
+
+SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
+		int, flags)
+{
+	return do_faccessat(dfd, filename, mode, flags);
+}
+
+SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
+{
+	return do_faccessat(AT_FDCWD, filename, mode, 0);
+}
+
+SYSCALL_DEFINE1(chdir, const char __user *, filename)
+{
+	struct path path;
+	int error;
+	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
+retry:
+	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
+	if (error)
+		goto out;
+
+	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
+	if (error)
+		goto dput_and_out;
+
+	set_fs_pwd(current->fs, &path);
+
+dput_and_out:
+	path_put(&path);
+	if (retry_estale(error, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
+out:
+	return error;
+}
+
+SYSCALL_DEFINE1(fchdir, unsigned int, fd)
+{
+	struct fd f = fdget_raw(fd);
+	int error;
+
+	error = -EBADF;
+	if (!f.file)
+		goto out;
+
+	error = -ENOTDIR;
+	if (!d_can_lookup(f.file->f_path.dentry))
+		goto out_putf;
+
+	error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
+	if (!error)
+		set_fs_pwd(current->fs, &f.file->f_path);
+out_putf:
+	fdput(f);
+out:
+	return error;
+}
+
+SYSCALL_DEFINE1(chroot, const char __user *, filename)
+{
+	struct path path;
+	int error;
+	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
+retry:
+	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
+	if (error)
+		goto out;
+
+	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
+	if (error)
+		goto dput_and_out;
+
+	error = -EPERM;
+	if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
+		goto dput_and_out;
+	error = security_path_chroot(&path);
+	if (error)
+		goto dput_and_out;
+
+	set_fs_root(current->fs, &path);
+	error = 0;
+dput_and_out:
+	path_put(&path);
+	if (retry_estale(error, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
+out:
+	return error;
+}
+
+int chmod_common(const struct path *path, umode_t mode)
+{
+	struct inode *inode = path->dentry->d_inode;
+	struct inode *delegated_inode = NULL;
+	struct iattr newattrs;
+	int error;
+
+	error = mnt_want_write(path->mnt);
+	if (error)
+		return error;
+retry_deleg:
+	inode_lock(inode);
+	error = security_path_chmod(path, mode);
+	if (error)
+		goto out_unlock;
+	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
+	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
+	error = notify_change(path->dentry, &newattrs, &delegated_inode);
+out_unlock:
+	inode_unlock(inode);
+	if (delegated_inode) {
+		error = break_deleg_wait(&delegated_inode);
+		if (!error)
+			goto retry_deleg;
+	}
+	mnt_drop_write(path->mnt);
+	return error;
+}
+
+int vfs_fchmod(struct file *file, umode_t mode)
+{
+	audit_file(file);
+	return chmod_common(&file->f_path, mode);
+}
+
+SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
+{
+	struct fd f = fdget(fd);
+	int err = -EBADF;
+
+	if (f.file) {
+		err = vfs_fchmod(f.file, mode);
+		fdput(f);
+	}
+	return err;
+}
+
+static int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
+{
+	struct path path;
+	int error;
+	unsigned int lookup_flags = LOOKUP_FOLLOW;
+retry:
+	error = user_path_at(dfd, filename, lookup_flags, &path);
+	if (!error) {
+		error = chmod_common(&path, mode);
+		path_put(&path);
+		if (retry_estale(error, lookup_flags)) {
+			lookup_flags |= LOOKUP_REVAL;
+			goto retry;
+		}
+	}
+	return error;
+}
+
+SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
+		umode_t, mode)
+{
+	return do_fchmodat(dfd, filename, mode);
+}
+
+SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
+{
+	return do_fchmodat(AT_FDCWD, filename, mode);
+}
+
+int chown_common(const struct path *path, uid_t user, gid_t group)
+{
+	struct inode *inode = path->dentry->d_inode;
+	struct inode *delegated_inode = NULL;
+	int error;
+	struct iattr newattrs;
+	kuid_t uid;
+	kgid_t gid;
+
+	uid = make_kuid(current_user_ns(), user);
+	gid = make_kgid(current_user_ns(), group);
+
+retry_deleg:
+	newattrs.ia_valid =  ATTR_CTIME;
+	if (user != (uid_t) -1) {
+		if (!uid_valid(uid))
+			return -EINVAL;
+		newattrs.ia_valid |= ATTR_UID;
+		newattrs.ia_uid = uid;
+	}
+	if (group != (gid_t) -1) {
+		if (!gid_valid(gid))
+			return -EINVAL;
+		newattrs.ia_valid |= ATTR_GID;
+		newattrs.ia_gid = gid;
+	}
+	inode_lock(inode);
+	if (!S_ISDIR(inode->i_mode))
+		newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV |
+				     setattr_should_drop_sgid(inode);
+	error = security_path_chown(path, uid, gid);
+	if (!error)
+		error = notify_change(path->dentry, &newattrs, &delegated_inode);
+	inode_unlock(inode);
+	if (delegated_inode) {
+		error = break_deleg_wait(&delegated_inode);
+		if (!error)
+			goto retry_deleg;
+	}
+	return error;
+}
+
+int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
+		int flag)
+{
+	struct path path;
+	int error = -EINVAL;
+	int lookup_flags;
+
+	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
+		goto out;
+
+	lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
+	if (flag & AT_EMPTY_PATH)
+		lookup_flags |= LOOKUP_EMPTY;
+retry:
+	error = user_path_at(dfd, filename, lookup_flags, &path);
+	if (error)
+		goto out;
+	error = mnt_want_write(path.mnt);
+	if (error)
+		goto out_release;
+	error = chown_common(&path, user, group);
+	mnt_drop_write(path.mnt);
+out_release:
+	path_put(&path);
+	if (retry_estale(error, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
+out:
+	return error;
+}
+
+SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
+		gid_t, group, int, flag)
+{
+	return do_fchownat(dfd, filename, user, group, flag);
+}
+
+SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
+{
+	return do_fchownat(AT_FDCWD, filename, user, group, 0);
+}
+
+SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
+{
+	return do_fchownat(AT_FDCWD, filename, user, group,
+			   AT_SYMLINK_NOFOLLOW);
+}
+
+int vfs_fchown(struct file *file, uid_t user, gid_t group)
+{
+	int error;
+
+	error = mnt_want_write_file(file);
+	if (error)
+		return error;
+	audit_file(file);
+	error = chown_common(&file->f_path, user, group);
+	mnt_drop_write_file(file);
+	return error;
+}
+
+int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
+{
+	struct fd f = fdget(fd);
+	int error = -EBADF;
+
+	if (f.file) {
+		error = vfs_fchown(f.file, user, group);
+		fdput(f);
+	}
+	return error;
+}
+
+SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
+{
+	return ksys_fchown(fd, user, group);
+}
+
+static int do_dentry_open(struct file *f,
+			  struct inode *inode,
+			  int (*open)(struct inode *, struct file *))
+{
+	static const struct file_operations empty_fops = {};
+	int error;
+
+	path_get(&f->f_path);
+	f->f_inode = inode;
+	f->f_mapping = inode->i_mapping;
+	f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
+	f->f_sb_err = file_sample_sb_err(f);
+
+	if (unlikely(f->f_flags & O_PATH)) {
+		f->f_mode = FMODE_PATH | FMODE_OPENED;
+		f->f_op = &empty_fops;
+		return 0;
+	}
+
+	if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
+		error = get_write_access(inode);
+		if (unlikely(error))
+			goto cleanup_file;
+		error = __mnt_want_write(f->f_path.mnt);
+		if (unlikely(error)) {
+			put_write_access(inode);
+			goto cleanup_file;
+		}
+		f->f_mode |= FMODE_WRITER;
+	}
+
+	/* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
+	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
+		f->f_mode |= FMODE_ATOMIC_POS;
+
+	f->f_op = fops_get(inode->i_fop);
+	if (WARN_ON(!f->f_op)) {
+		error = -ENODEV;
+		goto cleanup_all;
+	}
+
+	error = security_file_open(f);
+	if (error)
+		goto cleanup_all;
+
+	error = break_lease(locks_inode(f), f->f_flags);
+	if (error)
+		goto cleanup_all;
+
+	/* normally all 3 are set; ->open() can clear them if needed */
+	f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
+	if (!open)
+		open = f->f_op->open;
+	if (open) {
+		error = open(inode, f);
+		if (error)
+			goto cleanup_all;
+	}
+	f->f_mode |= FMODE_OPENED;
+	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+		i_readcount_inc(inode);
+	if ((f->f_mode & FMODE_READ) &&
+	     likely(f->f_op->read || f->f_op->read_iter))
+		f->f_mode |= FMODE_CAN_READ;
+	if ((f->f_mode & FMODE_WRITE) &&
+	     likely(f->f_op->write || f->f_op->write_iter))
+		f->f_mode |= FMODE_CAN_WRITE;
+
+	f->f_write_hint = WRITE_LIFE_NOT_SET;
+	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
+
+	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
+
+	/* NB: we're sure to have correct a_ops only after f_op->open */
+	if (f->f_flags & O_DIRECT) {
+		if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
+			return -EINVAL;
+	}
+
+	/*
+	 * XXX: Huge page cache doesn't support writing yet. Drop all page
+	 * cache for this file before processing writes.
+	 */
+	if ((f->f_mode & FMODE_WRITE) && filemap_nr_thps(inode->i_mapping))
+		truncate_pagecache(inode, 0);
+
+	return 0;
+
+cleanup_all:
+	if (WARN_ON_ONCE(error > 0))
+		error = -EINVAL;
+	fops_put(f->f_op);
+	if (f->f_mode & FMODE_WRITER) {
+		put_write_access(inode);
+		__mnt_drop_write(f->f_path.mnt);
+	}
+cleanup_file:
+	path_put(&f->f_path);
+	f->f_path.mnt = NULL;
+	f->f_path.dentry = NULL;
+	f->f_inode = NULL;
+	return error;
+}
+
+/**
+ * finish_open - finish opening a file
+ * @file: file pointer
+ * @dentry: pointer to dentry
+ * @open: open callback
+ * @opened: state of open
+ *
+ * This can be used to finish opening a file passed to i_op->atomic_open().
+ *
+ * If the open callback is set to NULL, then the standard f_op->open()
+ * filesystem callback is substituted.
+ *
+ * NB: the dentry reference is _not_ consumed.  If, for example, the dentry is
+ * the return value of d_splice_alias(), then the caller needs to perform dput()
+ * on it after finish_open().
+ *
+ * Returns zero on success or -errno if the open failed.
+ */
+int finish_open(struct file *file, struct dentry *dentry,
+		int (*open)(struct inode *, struct file *))
+{
+	BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
+
+	file->f_path.dentry = dentry;
+	return do_dentry_open(file, d_backing_inode(dentry), open);
+}
+EXPORT_SYMBOL(finish_open);
+
+/**
+ * finish_no_open - finish ->atomic_open() without opening the file
+ *
+ * @file: file pointer
+ * @dentry: dentry or NULL (as returned from ->lookup())
+ *
+ * This can be used to set the result of a successful lookup in ->atomic_open().
+ *
+ * NB: unlike finish_open() this function does consume the dentry reference and
+ * the caller need not dput() it.
+ *
+ * Returns "0" which must be the return value of ->atomic_open() after having
+ * called this function.
+ */
+int finish_no_open(struct file *file, struct dentry *dentry)
+{
+	file->f_path.dentry = dentry;
+	return 0;
+}
+EXPORT_SYMBOL(finish_no_open);
+
+char *file_path(struct file *filp, char *buf, int buflen)
+{
+	return d_path(&filp->f_path, buf, buflen);
+}
+EXPORT_SYMBOL(file_path);
+
+/**
+ * vfs_open - open the file at the given path
+ * @path: path to open
+ * @file: newly allocated file with f_flag initialized
+ * @cred: credentials to use
+ */
+int vfs_open(const struct path *path, struct file *file)
+{
+	file->f_path = *path;
+	return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
+}
+
+struct file *dentry_open(const struct path *path, int flags,
+			 const struct cred *cred)
+{
+	int error;
+	struct file *f;
+
+	validate_creds(cred);
+
+	/* We must always pass in a valid mount pointer. */
+	BUG_ON(!path->mnt);
+
+	f = alloc_empty_file(flags, cred);
+	if (!IS_ERR(f)) {
+		error = vfs_open(path, f);
+		if (error) {
+			fput(f);
+			f = ERR_PTR(error);
+		}
+	}
+	return f;
+}
+EXPORT_SYMBOL(dentry_open);
+
+struct file *open_with_fake_path(const struct path *path, int flags,
+				struct inode *inode, const struct cred *cred)
+{
+	struct file *f = alloc_empty_file_noaccount(flags, cred);
+	if (!IS_ERR(f)) {
+		int error;
+
+		f->f_path = *path;
+		error = do_dentry_open(f, inode, NULL);
+		if (error) {
+			fput(f);
+			f = ERR_PTR(error);
+		}
+	}
+	return f;
+}
+EXPORT_SYMBOL(open_with_fake_path);
+
+#define WILL_CREATE(flags)	(flags & (O_CREAT | __O_TMPFILE))
+#define O_PATH_FLAGS		(O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
+
+inline struct open_how build_open_how(int flags, umode_t mode)
+{
+	struct open_how how = {
+		.flags = flags & VALID_OPEN_FLAGS,
+		.mode = mode & S_IALLUGO,
+	};
+
+	/* O_PATH beats everything else. */
+	if (how.flags & O_PATH)
+		how.flags &= O_PATH_FLAGS;
+	/* Modes should only be set for create-like flags. */
+	if (!WILL_CREATE(how.flags))
+		how.mode = 0;
+	return how;
+}
+
+inline int build_open_flags(const struct open_how *how, struct open_flags *op)
+{
+	u64 flags = how->flags;
+	u64 strip = FMODE_NONOTIFY | O_CLOEXEC;
+	int lookup_flags = 0;
+	int acc_mode = ACC_MODE(flags);
+
+	BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
+			 "struct open_flags doesn't yet handle flags > 32 bits");
+
+	/*
+	 * Strip flags that either shouldn't be set by userspace like
+	 * FMODE_NONOTIFY or that aren't relevant in determining struct
+	 * open_flags like O_CLOEXEC.
+	 */
+	flags &= ~strip;
+
+	/*
+	 * Older syscalls implicitly clear all of the invalid flags or argument
+	 * values before calling build_open_flags(), but openat2(2) checks all
+	 * of its arguments.
+	 */
+	if (flags & ~VALID_OPEN_FLAGS)
+		return -EINVAL;
+	if (how->resolve & ~VALID_RESOLVE_FLAGS)
+		return -EINVAL;
+
+	/* Scoping flags are mutually exclusive. */
+	if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
+		return -EINVAL;
+
+	/* Deal with the mode. */
+	if (WILL_CREATE(flags)) {
+		if (how->mode & ~S_IALLUGO)
+			return -EINVAL;
+		op->mode = how->mode | S_IFREG;
+	} else {
+		if (how->mode != 0)
+			return -EINVAL;
+		op->mode = 0;
+	}
+
+	/*
+	 * In order to ensure programs get explicit errors when trying to use
+	 * O_TMPFILE on old kernels, O_TMPFILE is implemented such that it
+	 * looks like (O_DIRECTORY|O_RDWR & ~O_CREAT) to old kernels. But we
+	 * have to require userspace to explicitly set it.
+	 */
+	if (flags & __O_TMPFILE) {
+		if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
+			return -EINVAL;
+		if (!(acc_mode & MAY_WRITE))
+			return -EINVAL;
+	}
+	if (flags & O_PATH) {
+		/* O_PATH only permits certain other flags to be set. */
+		if (flags & ~O_PATH_FLAGS)
+			return -EINVAL;
+		acc_mode = 0;
+	}
+
+	/*
+	 * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
+	 * check for O_DSYNC if the need any syncing at all we enforce it's
+	 * always set instead of having to deal with possibly weird behaviour
+	 * for malicious applications setting only __O_SYNC.
+	 */
+	if (flags & __O_SYNC)
+		flags |= O_DSYNC;
+
+	op->open_flag = flags;
+
+	/* O_TRUNC implies we need access checks for write permissions */
+	if (flags & O_TRUNC)
+		acc_mode |= MAY_WRITE;
+
+	/* Allow the LSM permission hook to distinguish append
+	   access from general write access. */
+	if (flags & O_APPEND)
+		acc_mode |= MAY_APPEND;
+
+	op->acc_mode = acc_mode;
+
+	op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
+
+	if (flags & O_CREAT) {
+		op->intent |= LOOKUP_CREATE;
+		if (flags & O_EXCL) {
+			op->intent |= LOOKUP_EXCL;
+			flags |= O_NOFOLLOW;
+		}
+	}
+
+	if (flags & O_DIRECTORY)
+		lookup_flags |= LOOKUP_DIRECTORY;
+	if (!(flags & O_NOFOLLOW))
+		lookup_flags |= LOOKUP_FOLLOW;
+
+	if (how->resolve & RESOLVE_NO_XDEV)
+		lookup_flags |= LOOKUP_NO_XDEV;
+	if (how->resolve & RESOLVE_NO_MAGICLINKS)
+		lookup_flags |= LOOKUP_NO_MAGICLINKS;
+	if (how->resolve & RESOLVE_NO_SYMLINKS)
+		lookup_flags |= LOOKUP_NO_SYMLINKS;
+	if (how->resolve & RESOLVE_BENEATH)
+		lookup_flags |= LOOKUP_BENEATH;
+	if (how->resolve & RESOLVE_IN_ROOT)
+		lookup_flags |= LOOKUP_IN_ROOT;
+	if (how->resolve & RESOLVE_CACHED) {
+		/* Don't bother even trying for create/truncate/tmpfile open */
+		if (flags & (O_TRUNC | O_CREAT | __O_TMPFILE))
+			return -EAGAIN;
+		lookup_flags |= LOOKUP_CACHED;
+	}
+
+	op->lookup_flags = lookup_flags;
+	return 0;
+}
+
+/**
+ * file_open_name - open file and return file pointer
+ *
+ * @name:	struct filename containing path to open
+ * @flags:	open flags as per the open(2) second argument
+ * @mode:	mode for the new file if O_CREAT is set, else ignored
+ *
+ * This is the helper to open a file from kernelspace if you really
+ * have to.  But in generally you should not do this, so please move
+ * along, nothing to see here..
+ */
+struct file *file_open_name(struct filename *name, int flags, umode_t mode)
+{
+	struct open_flags op;
+	struct open_how how = build_open_how(flags, mode);
+	int err = build_open_flags(&how, &op);
+	if (err)
+		return ERR_PTR(err);
+	return do_filp_open(AT_FDCWD, name, &op);
+}
+
+/**
+ * filp_open - open file and return file pointer
+ *
+ * @filename:	path to open
+ * @flags:	open flags as per the open(2) second argument
+ * @mode:	mode for the new file if O_CREAT is set, else ignored
+ *
+ * This is the helper to open a file from kernelspace if you really
+ * have to.  But in generally you should not do this, so please move
+ * along, nothing to see here..
+ */
+struct file *filp_open(const char *filename, int flags, umode_t mode)
+{
+	struct filename *name = getname_kernel(filename);
+	struct file *file = ERR_CAST(name);
+	
+	if (!IS_ERR(name)) {
+		file = file_open_name(name, flags, mode);
+		putname(name);
+	}
+	return file;
+}
+EXPORT_SYMBOL(filp_open);
+
+struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
+			    const char *filename, int flags, umode_t mode)
+{
+	struct open_flags op;
+	struct open_how how = build_open_how(flags, mode);
+	int err = build_open_flags(&how, &op);
+	if (err)
+		return ERR_PTR(err);
+	return do_file_open_root(dentry, mnt, filename, &op);
+}
+EXPORT_SYMBOL(file_open_root);
+
+static long do_sys_openat2(int dfd, const char __user *filename,
+			   struct open_how *how)
+{
+	struct open_flags op;
+	int fd = build_open_flags(how, &op);
+	struct filename *tmp;
+
+	if (fd)
+		return fd;
+
+	tmp = getname(filename);
+	if (IS_ERR(tmp))
+		return PTR_ERR(tmp);
+
+	fd = get_unused_fd_flags(how->flags);
+	if (fd >= 0) {
+		struct file *f = do_filp_open(dfd, tmp, &op);
+		if (IS_ERR(f)) {
+			put_unused_fd(fd);
+			fd = PTR_ERR(f);
+		} else {
+			fsnotify_open(f);
+			fd_install(fd, f);
+		}
+	}
+	putname(tmp);
+	return fd;
+}
+
+long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
+{
+	struct open_how how = build_open_how(flags, mode);
+	return do_sys_openat2(dfd, filename, &how);
+}
+
+
+SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
+{
+	if (force_o_largefile())
+		flags |= O_LARGEFILE;
+	return do_sys_open(AT_FDCWD, filename, flags, mode);
+}
+
+SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
+		umode_t, mode)
+{
+	if (force_o_largefile())
+		flags |= O_LARGEFILE;
+	return do_sys_open(dfd, filename, flags, mode);
+}
+
+SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
+		struct open_how __user *, how, size_t, usize)
+{
+	int err;
+	struct open_how tmp;
+
+	BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
+	BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
+
+	if (unlikely(usize < OPEN_HOW_SIZE_VER0))
+		return -EINVAL;
+
+	err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
+	if (err)
+		return err;
+
+	/* O_LARGEFILE is only allowed for non-O_PATH. */
+	if (!(tmp.flags & O_PATH) && force_o_largefile())
+		tmp.flags |= O_LARGEFILE;
+
+	return do_sys_openat2(dfd, filename, &tmp);
+}
+
+#ifdef CONFIG_COMPAT
+/*
+ * Exactly like sys_open(), except that it doesn't set the
+ * O_LARGEFILE flag.
+ */
+COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
+{
+	return do_sys_open(AT_FDCWD, filename, flags, mode);
+}
+
+/*
+ * Exactly like sys_openat(), except that it doesn't set the
+ * O_LARGEFILE flag.
+ */
+COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
+{
+	return do_sys_open(dfd, filename, flags, mode);
+}
+#endif
+
+#ifndef __alpha__
+
+/*
+ * For backward compatibility?  Maybe this should be moved
+ * into arch/i386 instead?
+ */
+SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
+{
+	int flags = O_CREAT | O_WRONLY | O_TRUNC;
+
+	if (force_o_largefile())
+		flags |= O_LARGEFILE;
+	return do_sys_open(AT_FDCWD, pathname, flags, mode);
+}
+#endif
+
+/*
+ * "id" is the POSIX thread ID. We use the
+ * files pointer for this..
+ */
+int filp_close(struct file *filp, fl_owner_t id)
+{
+	int retval = 0;
+
+	if (!file_count(filp)) {
+		printk(KERN_ERR "VFS: Close: file count is 0\n");
+		return 0;
+	}
+
+	if (filp->f_op->flush)
+		retval = filp->f_op->flush(filp, id);
+
+	if (likely(!(filp->f_mode & FMODE_PATH))) {
+		dnotify_flush(filp, id);
+		locks_remove_posix(filp, id);
+	}
+	fput(filp);
+	return retval;
+}
+
+EXPORT_SYMBOL(filp_close);
+
+/*
+ * Careful here! We test whether the file pointer is NULL before
+ * releasing the fd. This ensures that one clone task can't release
+ * an fd while another clone is opening it.
+ */
+SYSCALL_DEFINE1(close, unsigned int, fd)
+{
+	int retval = __close_fd(current->files, fd);
+
+	/* can't restart close syscall because file table entry was cleared */
+	if (unlikely(retval == -ERESTARTSYS ||
+		     retval == -ERESTARTNOINTR ||
+		     retval == -ERESTARTNOHAND ||
+		     retval == -ERESTART_RESTARTBLOCK))
+		retval = -EINTR;
+
+	return retval;
+}
+
+/**
+ * close_range() - Close all file descriptors in a given range.
+ *
+ * @fd:     starting file descriptor to close
+ * @max_fd: last file descriptor to close
+ * @flags:  reserved for future extensions
+ *
+ * This closes a range of file descriptors. All file descriptors
+ * from @fd up to and including @max_fd are closed.
+ * Currently, errors to close a given file descriptor are ignored.
+ */
+SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
+		unsigned int, flags)
+{
+	return __close_range(fd, max_fd, flags);
+}
+
+/*
+ * This routine simulates a hangup on the tty, to arrange that users
+ * are given clean terminals at login time.
+ */
+SYSCALL_DEFINE0(vhangup)
+{
+	if (capable(CAP_SYS_TTY_CONFIG)) {
+		tty_vhangup_self();
+		return 0;
+	}
+	return -EPERM;
+}
+
+/*
+ * Called when an inode is about to be open.
+ * We use this to disallow opening large files on 32bit systems if
+ * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
+ * on this flag in sys_open.
+ */
+int generic_file_open(struct inode * inode, struct file * filp)
+{
+	if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
+		return -EOVERFLOW;
+	return 0;
+}
+
+EXPORT_SYMBOL(generic_file_open);
+
+/*
+ * This is used by subsystems that don't want seekable
+ * file descriptors. The function is not supposed to ever fail, the only
+ * reason it returns an 'int' and not 'void' is so that it can be plugged
+ * directly into file_operations structure.
+ */
+int nonseekable_open(struct inode *inode, struct file *filp)
+{
+	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
+	return 0;
+}
+
+EXPORT_SYMBOL(nonseekable_open);
+
+/*
+ * stream_open is used by subsystems that want stream-like file descriptors.
+ * Such file descriptors are not seekable and don't have notion of position
+ * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
+ * Contrary to file descriptors of other regular files, .read() and .write()
+ * can run simultaneously.
+ *
+ * stream_open never fails and is marked to return int so that it could be
+ * directly used as file_operations.open .
+ */
+int stream_open(struct inode *inode, struct file *filp)
+{
+	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
+	filp->f_mode |= FMODE_STREAM;
+	return 0;
+}
+
+EXPORT_SYMBOL(stream_open);