init android origin source code

1 files changed, 1143 insertions, 0 deletions

diff --git a/ANDROID_3.4.5/fs/open.c b/ANDROID_3.4.5/fs/open.c
new file mode 100644
index 00000000..3f1108b1
--- /dev/null
+++ b/ANDROID_3.4.5/fs/open.c
@@ -0,0 +1,1143 @@
+/*
+ *  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 <asm/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 "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 on truncate too */
+	ret = should_remove_suid(dentry);
+	if (ret)
+		newattrs.ia_valid |= ret | ATTR_FORCE;
+
+	mutex_lock(&dentry->d_inode->i_mutex);
+	ret = notify_change(dentry, &newattrs);
+	mutex_unlock(&dentry->d_inode->i_mutex);
+	return ret;
+}
+
+static long do_sys_truncate(const char __user *pathname, loff_t length)
+{
+	struct path path;
+	struct inode *inode;
+	int error;
+
+	error = -EINVAL;
+	if (length < 0)	/* sorry, but loff_t says... */
+		goto out;
+
+	error = user_path(pathname, &path);
+	if (error)
+		goto out;
+	inode = path.dentry->d_inode;
+
+	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
+	error = -EISDIR;
+	if (S_ISDIR(inode->i_mode))
+		goto dput_and_out;
+
+	error = -EINVAL;
+	if (!S_ISREG(inode->i_mode))
+		goto dput_and_out;
+
+	error = mnt_want_write(path.mnt);
+	if (error)
+		goto dput_and_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);
+dput_and_out:
+	path_put(&path);
+out:
+	return error;
+}
+
+SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
+{
+	return do_sys_truncate(path, length);
+}
+
+static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
+{
+	struct inode * inode;
+	struct dentry *dentry;
+	struct file * file;
+	int error;
+
+	error = -EINVAL;
+	if (length < 0)
+		goto out;
+	error = -EBADF;
+	file = fget(fd);
+	if (!file)
+		goto out;
+
+	/* explicitly opened as large or we are on 64-bit box */
+	if (file->f_flags & O_LARGEFILE)
+		small = 0;
+
+	dentry = file->f_path.dentry;
+	inode = dentry->d_inode;
+	error = -EINVAL;
+	if (!S_ISREG(inode->i_mode) || !(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;
+	if (IS_APPEND(inode))
+		goto out_putf;
+
+	error = locks_verify_truncate(inode, file, length);
+	if (!error)
+		error = security_path_truncate(&file->f_path);
+	if (!error)
+		error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
+out_putf:
+	fput(file);
+out:
+	return error;
+}
+
+SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
+{
+	long ret = do_sys_ftruncate(fd, length, 1);
+	/* avoid REGPARM breakage on x86: */
+	asmlinkage_protect(2, ret, fd, length);
+	return ret;
+}
+
+/* LFS versions of truncate are only needed on 32 bit machines */
+#if BITS_PER_LONG == 32
+SYSCALL_DEFINE(truncate64)(const char __user * path, loff_t length)
+{
+	return do_sys_truncate(path, length);
+}
+#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
+asmlinkage long SyS_truncate64(long path, loff_t length)
+{
+	return SYSC_truncate64((const char __user *) path, length);
+}
+SYSCALL_ALIAS(sys_truncate64, SyS_truncate64);
+#endif
+
+SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length)
+{
+	long ret = do_sys_ftruncate(fd, length, 0);
+	/* avoid REGPARM breakage on x86: */
+	asmlinkage_protect(2, ret, fd, length);
+	return ret;
+}
+#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
+asmlinkage long SyS_ftruncate64(long fd, loff_t length)
+{
+	return SYSC_ftruncate64((unsigned int) fd, length);
+}
+SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64);
+#endif
+#endif /* BITS_PER_LONG == 32 */
+
+
+int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
+{
+	struct inode *inode = file->f_path.dentry->d_inode;
+	long ret;
+
+	if (offset < 0 || len <= 0)
+		return -EINVAL;
+
+	/* Return error if mode is not supported */
+	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+		return -EOPNOTSUPP;
+
+	/* Punch hole must have keep size set */
+	if ((mode & FALLOC_FL_PUNCH_HOLE) &&
+	    !(mode & FALLOC_FL_KEEP_SIZE))
+		return -EOPNOTSUPP;
+
+	if (!(file->f_mode & FMODE_WRITE))
+		return -EBADF;
+
+	/* It's not possible punch hole on append only file */
+	if (mode & FALLOC_FL_PUNCH_HOLE && IS_APPEND(inode))
+		return -EPERM;
+
+	if (IS_IMMUTABLE(inode))
+		return -EPERM;
+
+	/*
+	 * 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;
+
+	/*
+	 * Let individual file system decide if it supports preallocation
+	 * for directories or not.
+	 */
+	if (!S_ISREG(inode->i_mode) && !S_ISDIR(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;
+
+	return file->f_op->fallocate(file, mode, offset, len);
+}
+
+SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len)
+{
+	struct file *file;
+	int error = -EBADF;
+
+	file = fget(fd);
+	if (file) {
+		error = do_fallocate(file, mode, offset, len);
+		fput(file);
+	}
+
+	return error;
+}
+
+#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
+asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len)
+{
+	return SYSC_fallocate((int)fd, (int)mode, offset, len);
+}
+SYSCALL_ALIAS(sys_fallocate, SyS_fallocate);
+#endif
+
+/*
+ * 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.
+ */
+SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
+{
+	const struct cred *old_cred;
+	struct cred *override_cred;
+	struct path path;
+	struct inode *inode;
+	int res;
+
+	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
+		return -EINVAL;
+
+	override_cred = prepare_creds();
+	if (!override_cred)
+		return -ENOMEM;
+
+	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 */
+		if (override_cred->uid)
+			cap_clear(override_cred->cap_effective);
+		else
+			override_cred->cap_effective =
+				override_cred->cap_permitted;
+	}
+
+	old_cred = override_creds(override_cred);
+
+	res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
+	if (res)
+		goto out;
+
+	inode = path.dentry->d_inode;
+
+	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.mnt->mnt_flags & MNT_NOEXEC)
+			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);
+out:
+	revert_creds(old_cred);
+	put_cred(override_cred);
+	return res;
+}
+
+SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
+{
+	return sys_faccessat(AT_FDCWD, filename, mode);
+}
+
+SYSCALL_DEFINE1(chdir, const char __user *, filename)
+{
+	struct path path;
+	int error;
+
+	error = user_path_dir(filename, &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);
+out:
+	return error;
+}
+
+SYSCALL_DEFINE1(fchdir, unsigned int, fd)
+{
+	struct file *file;
+	struct inode *inode;
+	int error, fput_needed;
+
+	error = -EBADF;
+	file = fget_raw_light(fd, &fput_needed);
+	if (!file)
+		goto out;
+
+	inode = file->f_path.dentry->d_inode;
+
+	error = -ENOTDIR;
+	if (!S_ISDIR(inode->i_mode))
+		goto out_putf;
+
+	error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
+	if (!error)
+		set_fs_pwd(current->fs, &file->f_path);
+out_putf:
+	fput_light(file, fput_needed);
+out:
+	return error;
+}
+
+SYSCALL_DEFINE1(chroot, const char __user *, filename)
+{
+	struct path path;
+	int error;
+
+	error = user_path_dir(filename, &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 (!capable(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);
+out:
+	return error;
+}
+
+static int chmod_common(struct path *path, umode_t mode)
+{
+	struct inode *inode = path->dentry->d_inode;
+	struct iattr newattrs;
+	int error;
+
+	error = mnt_want_write(path->mnt);
+	if (error)
+		return error;
+	mutex_lock(&inode->i_mutex);
+	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);
+out_unlock:
+	mutex_unlock(&inode->i_mutex);
+	mnt_drop_write(path->mnt);
+	return error;
+}
+
+SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
+{
+	struct file * file;
+	int err = -EBADF;
+
+	file = fget(fd);
+	if (file) {
+		audit_inode(NULL, file->f_path.dentry);
+		err = chmod_common(&file->f_path, mode);
+		fput(file);
+	}
+	return err;
+}
+
+SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode)
+{
+	struct path path;
+	int error;
+
+	error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
+	if (!error) {
+		error = chmod_common(&path, mode);
+		path_put(&path);
+	}
+	return error;
+}
+
+SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
+{
+	return sys_fchmodat(AT_FDCWD, filename, mode);
+}
+
+static int chown_common(struct path *path, uid_t user, gid_t group)
+{
+	struct inode *inode = path->dentry->d_inode;
+	int error;
+	struct iattr newattrs;
+
+	newattrs.ia_valid =  ATTR_CTIME;
+	if (user != (uid_t) -1) {
+		newattrs.ia_valid |= ATTR_UID;
+		newattrs.ia_uid = user;
+	}
+	if (group != (gid_t) -1) {
+		newattrs.ia_valid |= ATTR_GID;
+		newattrs.ia_gid = group;
+	}
+	if (!S_ISDIR(inode->i_mode))
+		newattrs.ia_valid |=
+			ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
+	mutex_lock(&inode->i_mutex);
+	error = security_path_chown(path, user, group);
+	if (!error)
+		error = notify_change(path->dentry, &newattrs);
+	mutex_unlock(&inode->i_mutex);
+
+	return error;
+}
+
+SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
+{
+	struct path path;
+	int error;
+
+	error = user_path(filename, &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);
+out:
+	return error;
+}
+
+SYSCALL_DEFINE5(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;
+	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);
+out:
+	return error;
+}
+
+SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
+{
+	struct path path;
+	int error;
+
+	error = user_lpath(filename, &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);
+out:
+	return error;
+}
+
+SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
+{
+	struct file * file;
+	int error = -EBADF;
+	struct dentry * dentry;
+
+	file = fget(fd);
+	if (!file)
+		goto out;
+
+	error = mnt_want_write_file(file);
+	if (error)
+		goto out_fput;
+	dentry = file->f_path.dentry;
+	audit_inode(NULL, dentry);
+	error = chown_common(&file->f_path, user, group);
+	mnt_drop_write_file(file);
+out_fput:
+	fput(file);
+out:
+	return error;
+}
+
+/*
+ * You have to be very careful that these write
+ * counts get cleaned up in error cases and
+ * upon __fput().  This should probably never
+ * be called outside of __dentry_open().
+ */
+static inline int __get_file_write_access(struct inode *inode,
+					  struct vfsmount *mnt)
+{
+	int error;
+	error = get_write_access(inode);
+	if (error)
+		return error;
+	/*
+	 * Do not take mount writer counts on
+	 * special files since no writes to
+	 * the mount itself will occur.
+	 */
+	if (!special_file(inode->i_mode)) {
+		/*
+		 * Balanced in __fput()
+		 */
+		error = mnt_want_write(mnt);
+		if (error)
+			put_write_access(inode);
+	}
+	return error;
+}
+
+static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
+					struct file *f,
+					int (*open)(struct inode *, struct file *),
+					const struct cred *cred)
+{
+	static const struct file_operations empty_fops = {};
+	struct inode *inode;
+	int error;
+
+	f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
+				FMODE_PREAD | FMODE_PWRITE;
+
+	if (unlikely(f->f_flags & O_PATH))
+		f->f_mode = FMODE_PATH;
+
+	inode = dentry->d_inode;
+	if (f->f_mode & FMODE_WRITE) {
+		error = __get_file_write_access(inode, mnt);
+		if (error)
+			goto cleanup_file;
+		if (!special_file(inode->i_mode))
+			file_take_write(f);
+	}
+
+	f->f_mapping = inode->i_mapping;
+	f->f_path.dentry = dentry;
+	f->f_path.mnt = mnt;
+	f->f_pos = 0;
+	file_sb_list_add(f, inode->i_sb);
+
+	if (unlikely(f->f_mode & FMODE_PATH)) {
+		f->f_op = &empty_fops;
+		return f;
+	}
+
+	f->f_op = fops_get(inode->i_fop);
+
+	error = security_dentry_open(f, cred);
+	if (error)
+		goto cleanup_all;
+
+	error = break_lease(inode, f->f_flags);
+	if (error)
+		goto cleanup_all;
+
+	if (!open && f->f_op)
+		open = f->f_op->open;
+	if (open) {
+		error = open(inode, f);
+		if (error)
+			goto cleanup_all;
+	}
+	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+		i_readcount_inc(inode);
+
+	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) &&
+		    (!f->f_mapping->a_ops->get_xip_mem))) {
+			fput(f);
+			f = ERR_PTR(-EINVAL);
+		}
+	}
+
+	return f;
+
+cleanup_all:
+	fops_put(f->f_op);
+	if (f->f_mode & FMODE_WRITE) {
+		put_write_access(inode);
+		if (!special_file(inode->i_mode)) {
+			/*
+			 * We don't consider this a real
+			 * mnt_want/drop_write() pair
+			 * because it all happenend right
+			 * here, so just reset the state.
+			 */
+			file_reset_write(f);
+			mnt_drop_write(mnt);
+		}
+	}
+	file_sb_list_del(f);
+	f->f_path.dentry = NULL;
+	f->f_path.mnt = NULL;
+cleanup_file:
+	put_filp(f);
+	dput(dentry);
+	mntput(mnt);
+	return ERR_PTR(error);
+}
+
+/**
+ * lookup_instantiate_filp - instantiates the open intent filp
+ * @nd: pointer to nameidata
+ * @dentry: pointer to dentry
+ * @open: open callback
+ *
+ * Helper for filesystems that want to use lookup open intents and pass back
+ * a fully instantiated struct file to the caller.
+ * This function is meant to be called from within a filesystem's
+ * lookup method.
+ * Beware of calling it for non-regular files! Those ->open methods might block
+ * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
+ * leading to a deadlock, as nobody can open that fifo anymore, because
+ * another process to open fifo will block on locked parent when doing lookup).
+ * Note that in case of error, nd->intent.open.file is destroyed, but the
+ * path information remains valid.
+ * If the open callback is set to NULL, then the standard f_op->open()
+ * filesystem callback is substituted.
+ */
+struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
+		int (*open)(struct inode *, struct file *))
+{
+	const struct cred *cred = current_cred();
+
+	if (IS_ERR(nd->intent.open.file))
+		goto out;
+	if (IS_ERR(dentry))
+		goto out_err;
+	nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
+					     nd->intent.open.file,
+					     open, cred);
+out:
+	return nd->intent.open.file;
+out_err:
+	release_open_intent(nd);
+	nd->intent.open.file = ERR_CAST(dentry);
+	goto out;
+}
+EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
+
+/**
+ * nameidata_to_filp - convert a nameidata to an open filp.
+ * @nd: pointer to nameidata
+ * @flags: open flags
+ *
+ * Note that this function destroys the original nameidata
+ */
+struct file *nameidata_to_filp(struct nameidata *nd)
+{
+	const struct cred *cred = current_cred();
+	struct file *filp;
+
+	/* Pick up the filp from the open intent */
+	filp = nd->intent.open.file;
+	nd->intent.open.file = NULL;
+
+	/* Has the filesystem initialised the file for us? */
+	if (filp->f_path.dentry == NULL) {
+		path_get(&nd->path);
+		filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp,
+				     NULL, cred);
+	}
+	return filp;
+}
+
+/*
+ * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
+ * error.
+ */
+struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, 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(!mnt);
+
+	error = -ENFILE;
+	f = get_empty_filp();
+	if (f == NULL) {
+		dput(dentry);
+		mntput(mnt);
+		return ERR_PTR(error);
+	}
+
+	f->f_flags = flags;
+	return __dentry_open(dentry, mnt, f, NULL, cred);
+}
+EXPORT_SYMBOL(dentry_open);
+
+static void __put_unused_fd(struct files_struct *files, unsigned int fd)
+{
+	struct fdtable *fdt = files_fdtable(files);
+	__clear_open_fd(fd, fdt);
+	if (fd < files->next_fd)
+		files->next_fd = fd;
+}
+
+void put_unused_fd(unsigned int fd)
+{
+	struct files_struct *files = current->files;
+	spin_lock(&files->file_lock);
+	__put_unused_fd(files, fd);
+	spin_unlock(&files->file_lock);
+}
+
+EXPORT_SYMBOL(put_unused_fd);
+
+/*
+ * Install a file pointer in the fd array.
+ *
+ * The VFS is full of places where we drop the files lock between
+ * setting the open_fds bitmap and installing the file in the file
+ * array.  At any such point, we are vulnerable to a dup2() race
+ * installing a file in the array before us.  We need to detect this and
+ * fput() the struct file we are about to overwrite in this case.
+ *
+ * It should never happen - if we allow dup2() do it, _really_ bad things
+ * will follow.
+ */
+
+void fd_install(unsigned int fd, struct file *file)
+{
+	struct files_struct *files = current->files;
+	struct fdtable *fdt;
+	spin_lock(&files->file_lock);
+	fdt = files_fdtable(files);
+	BUG_ON(fdt->fd[fd] != NULL);
+	rcu_assign_pointer(fdt->fd[fd], file);
+	spin_unlock(&files->file_lock);
+}
+
+EXPORT_SYMBOL(fd_install);
+
+static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
+{
+	int lookup_flags = 0;
+	int acc_mode;
+
+	if (!(flags & O_CREAT))
+		mode = 0;
+	op->mode = mode;
+
+	/* Must never be set by userspace */
+	flags &= ~FMODE_NONOTIFY;
+
+	/*
+	 * 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;
+
+	/*
+	 * If we have O_PATH in the open flag. Then we
+	 * cannot have anything other than the below set of flags
+	 */
+	if (flags & O_PATH) {
+		flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
+		acc_mode = 0;
+	} else {
+		acc_mode = MAY_OPEN | ACC_MODE(flags);
+	}
+
+	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;
+	}
+
+	if (flags & O_DIRECTORY)
+		lookup_flags |= LOOKUP_DIRECTORY;
+	if (!(flags & O_NOFOLLOW))
+		lookup_flags |= LOOKUP_FOLLOW;
+	return lookup_flags;
+}
+
+/**
+ * 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 open_flags op;
+	int lookup = build_open_flags(flags, mode, &op);
+	return do_filp_open(AT_FDCWD, filename, &op, lookup);
+}
+EXPORT_SYMBOL(filp_open);
+
+struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
+			    const char *filename, int flags)
+{
+	struct open_flags op;
+	int lookup = build_open_flags(flags, 0, &op);
+	if (flags & O_CREAT)
+		return ERR_PTR(-EINVAL);
+	if (!filename && (flags & O_DIRECTORY))
+		if (!dentry->d_inode->i_op->lookup)
+			return ERR_PTR(-ENOTDIR);
+	return do_file_open_root(dentry, mnt, filename, &op, lookup);
+}
+EXPORT_SYMBOL(file_open_root);
+
+long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
+{
+	struct open_flags op;
+	int lookup = build_open_flags(flags, mode, &op);
+	char *tmp = getname(filename);
+	int fd = PTR_ERR(tmp);
+
+	if (!IS_ERR(tmp)) {
+		fd = get_unused_fd_flags(flags);
+		if (fd >= 0) {
+			struct file *f = do_filp_open(dfd, tmp, &op, lookup);
+			if (IS_ERR(f)) {
+				put_unused_fd(fd);
+				fd = PTR_ERR(f);
+			} else {
+				fsnotify_open(f);
+				fd_install(fd, f);
+			}
+		}
+		putname(tmp);
+	}
+	return fd;
+}
+
+SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
+{
+	long ret;
+
+	if (force_o_largefile())
+		flags |= O_LARGEFILE;
+
+	ret = do_sys_open(AT_FDCWD, filename, flags, mode);
+	/* avoid REGPARM breakage on x86: */
+	asmlinkage_protect(3, ret, filename, flags, mode);
+	return ret;
+}
+
+SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
+		umode_t, mode)
+{
+	long ret;
+
+	if (force_o_largefile())
+		flags |= O_LARGEFILE;
+
+	ret = do_sys_open(dfd, filename, flags, mode);
+	/* avoid REGPARM breakage on x86: */
+	asmlinkage_protect(4, ret, dfd, filename, flags, mode);
+	return ret;
+}
+
+#ifndef __alpha__
+
+/*
+ * For backward compatibility?  Maybe this should be moved
+ * into arch/i386 instead?
+ */
+SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
+{
+	return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, 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 && 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)
+{
+	struct file * filp;
+	struct files_struct *files = current->files;
+	struct fdtable *fdt;
+	int retval;
+
+	spin_lock(&files->file_lock);
+	fdt = files_fdtable(files);
+	if (fd >= fdt->max_fds)
+		goto out_unlock;
+	filp = fdt->fd[fd];
+	if (!filp)
+		goto out_unlock;
+	rcu_assign_pointer(fdt->fd[fd], NULL);
+	__clear_close_on_exec(fd, fdt);
+	__put_unused_fd(files, fd);
+	spin_unlock(&files->file_lock);
+	retval = filp_close(filp, files);
+
+	/* 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;
+
+out_unlock:
+	spin_unlock(&files->file_lock);
+	return -EBADF;
+}
+EXPORT_SYMBOL(sys_close);
+
+/*
+ * 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);