open.c 27.0 KB
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/*
 *  linux/fs/open.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/string.h>
#include <linux/mm.h>
#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/fsnotify.h>
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#include <linux/module.h>
#include <linux/tty.h>
#include <linux/namei.h>
#include <linux/backing-dev.h>
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#include <linux/capability.h>
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#include <linux/securebits.h>
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#include <linux/security.h>
#include <linux/mount.h>
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#include <linux/fcntl.h>
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#include <linux/slab.h>
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#include <asm/uaccess.h>
#include <linux/fs.h>
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#include <linux/personality.h>
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#include <linux/pagemap.h>
#include <linux/syscalls.h>
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#include <linux/rcupdate.h>
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#include <linux/audit.h>
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#include <linux/falloc.h>
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#include <linux/fs_struct.h>
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#include <linux/ima.h>
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#include <linux/dnotify.h>
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#include "internal.h"

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int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
	struct file *filp)
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{
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	int ret;
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	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;
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	newattrs.ia_valid = ATTR_SIZE | time_attrs;
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	if (filp) {
		newattrs.ia_file = filp;
		newattrs.ia_valid |= ATTR_FILE;
	}
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	/* Remove suid/sgid on truncate too */
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	ret = should_remove_suid(dentry);
	if (ret)
		newattrs.ia_valid |= ret | ATTR_FORCE;
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58
	mutex_lock(&dentry->d_inode->i_mutex);
59
	ret = notify_change(dentry, &newattrs);
60
	mutex_unlock(&dentry->d_inode->i_mutex);
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	return ret;
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}

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static long do_sys_truncate(const char __user *pathname, loff_t length)
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{
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	struct path path;
	struct inode *inode;
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	int error;

	error = -EINVAL;
	if (length < 0)	/* sorry, but loff_t says... */
		goto out;

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	error = user_path(pathname, &path);
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	if (error)
		goto out;
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	inode = path.dentry->d_inode;
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	/* 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;

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	error = mnt_want_write(path.mnt);
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	if (error)
		goto dput_and_out;

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	error = inode_permission(inode, MAY_WRITE);
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	if (error)
		goto mnt_drop_write_and_out;
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	error = -EPERM;
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	if (IS_APPEND(inode))
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		goto mnt_drop_write_and_out;
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	error = get_write_access(inode);
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	if (error)
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		goto mnt_drop_write_and_out;
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	/*
	 * Make sure that there are no leases.  get_write_access() protects
	 * against the truncate racing with a lease-granting setlease().
	 */
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	error = break_lease(inode, O_WRONLY);
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	if (error)
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		goto put_write_and_out;
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	error = locks_verify_truncate(inode, NULL, length);
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	if (!error)
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		error = security_path_truncate(&path);
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	if (!error)
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		error = do_truncate(path.dentry, length, 0, NULL);
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put_write_and_out:
	put_write_access(inode);
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mnt_drop_write_and_out:
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	mnt_drop_write(path.mnt);
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dput_and_out:
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	path_put(&path);
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out:
	return error;
}

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SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
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{
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	return do_sys_truncate(path, length);
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}

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static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
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{
	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;

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	dentry = file->f_path.dentry;
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	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);
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	if (!error)
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		error = security_path_truncate(&file->f_path);
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	if (!error)
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		error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
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out_putf:
	fput(file);
out:
	return error;
}

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SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
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{
180
	long ret = do_sys_ftruncate(fd, length, 1);
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	/* avoid REGPARM breakage on x86: */
182
	asmlinkage_protect(2, ret, fd, length);
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	return ret;
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}

/* LFS versions of truncate are only needed on 32 bit machines */
#if BITS_PER_LONG == 32
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SYSCALL_DEFINE(truncate64)(const char __user * path, loff_t length)
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{
	return do_sys_truncate(path, length);
}
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#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
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SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length)
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{
202
	long ret = do_sys_ftruncate(fd, length, 0);
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	/* avoid REGPARM breakage on x86: */
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	asmlinkage_protect(2, ret, fd, length);
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	return ret;
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}
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#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);
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#endif
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#endif /* BITS_PER_LONG == 32 */
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int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
218
{
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	struct inode *inode = file->f_path.dentry->d_inode;
	long ret;
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	if (offset < 0 || len <= 0)
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		return -EINVAL;
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	/* Return error if mode is not supported */
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	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))
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		return -EOPNOTSUPP;
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	if (!(file->f_mode & FMODE_WRITE))
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		return -EBADF;
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	/* 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;

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	/*
	 * Revalidate the write permissions, in case security policy has
	 * changed since the files were opened.
	 */
	ret = security_file_permission(file, MAY_WRITE);
	if (ret)
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		return ret;
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	if (S_ISFIFO(inode->i_mode))
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		return -ESPIPE;
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	/*
	 * Let individual file system decide if it supports preallocation
	 * for directories or not.
	 */
	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
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		return -ENODEV;
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	/* Check for wrap through zero too */
	if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
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		return -EFBIG;
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266
	if (!file->f_op->fallocate)
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		return -EOPNOTSUPP;
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269
	return file->f_op->fallocate(file, mode, offset, len);
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}

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;
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}
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#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
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/*
 * 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.
 */
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SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
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{
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	const struct cred *old_cred;
	struct cred *override_cred;
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	struct path path;
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	struct inode *inode;
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	int res;

	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
		return -EINVAL;

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	override_cred = prepare_creds();
	if (!override_cred)
		return -ENOMEM;
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	override_cred->fsuid = override_cred->uid;
	override_cred->fsgid = override_cred->gid;
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	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
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		/* Clear the capabilities if we switch to a non-root user */
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		if (override_cred->uid)
			cap_clear(override_cred->cap_effective);
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		else
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			override_cred->cap_effective =
				override_cred->cap_permitted;
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	}
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	old_cred = override_creds(override_cred);

328
	res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
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	if (res)
		goto out;

332
	inode = path.dentry->d_inode;
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	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
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		/*
		 * MAY_EXEC on regular files is denied if the fs is mounted
		 * with the "noexec" flag.
		 */
		res = -EACCES;
340
		if (path.mnt->mnt_flags & MNT_NOEXEC)
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			goto out_path_release;
	}

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	res = inode_permission(inode, mode | MAY_ACCESS);
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	/* SuS v2 requires we report a read only fs too */
346
	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
347
		goto out_path_release;
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	/*
	 * 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.
	 */
358
	if (__mnt_is_readonly(path.mnt))
359
		res = -EROFS;
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361
out_path_release:
362
	path_put(&path);
363
out:
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	revert_creds(old_cred);
	put_cred(override_cred);
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	return res;
}

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SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
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{
	return sys_faccessat(AT_FDCWD, filename, mode);
}

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SYSCALL_DEFINE1(chdir, const char __user *, filename)
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{
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	struct path path;
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	int error;

379
	error = user_path_dir(filename, &path);
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	if (error)
		goto out;

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	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
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	if (error)
		goto dput_and_out;

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	set_fs_pwd(current->fs, &path);
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dput_and_out:
390
	path_put(&path);
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out:
	return error;
}

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SYSCALL_DEFINE1(fchdir, unsigned int, fd)
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{
	struct file *file;
	struct inode *inode;
	int error;

	error = -EBADF;
	file = fget(fd);
	if (!file)
		goto out;

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	inode = file->f_path.dentry->d_inode;
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	error = -ENOTDIR;
	if (!S_ISDIR(inode->i_mode))
		goto out_putf;

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	error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
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	if (!error)
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		set_fs_pwd(current->fs, &file->f_path);
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out_putf:
	fput(file);
out:
	return error;
}

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SYSCALL_DEFINE1(chroot, const char __user *, filename)
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{
423
	struct path path;
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	int error;

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	error = user_path_dir(filename, &path);
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	if (error)
		goto out;

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	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
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	if (error)
		goto dput_and_out;

	error = -EPERM;
	if (!capable(CAP_SYS_CHROOT))
		goto dput_and_out;
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	error = security_path_chroot(&path);
	if (error)
		goto dput_and_out;
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441
	set_fs_root(current->fs, &path);
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	error = 0;
dput_and_out:
444
	path_put(&path);
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out:
	return error;
}

449
SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode)
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{
	struct inode * inode;
	struct dentry * dentry;
	struct file * file;
	int err = -EBADF;
	struct iattr newattrs;

	file = fget(fd);
	if (!file)
		goto out;

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	dentry = file->f_path.dentry;
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	inode = dentry->d_inode;

464
	audit_inode(NULL, dentry);
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	err = mnt_want_write_file(file);
467
	if (err)
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		goto out_putf;
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	mutex_lock(&inode->i_mutex);
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	err = security_path_chmod(dentry, file->f_vfsmnt, mode);
	if (err)
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		goto out_unlock;
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	if (mode == (mode_t) -1)
		mode = inode->i_mode;
	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
	err = notify_change(dentry, &newattrs);
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out_unlock:
479
	mutex_unlock(&inode->i_mutex);
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	mnt_drop_write(file->f_path.mnt);
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out_putf:
	fput(file);
out:
	return err;
}

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SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode)
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{
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	struct path path;
	struct inode *inode;
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	int error;
	struct iattr newattrs;

494
	error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
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	if (error)
		goto out;
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	inode = path.dentry->d_inode;
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499
	error = mnt_want_write(path.mnt);
500
	if (error)
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		goto dput_and_out;
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	mutex_lock(&inode->i_mutex);
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	error = security_path_chmod(path.dentry, path.mnt, mode);
	if (error)
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		goto out_unlock;
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	if (mode == (mode_t) -1)
		mode = inode->i_mode;
	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
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	error = notify_change(path.dentry, &newattrs);
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out_unlock:
512
	mutex_unlock(&inode->i_mutex);
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	mnt_drop_write(path.mnt);
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dput_and_out:
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	path_put(&path);
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out:
	return error;
}

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SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_t, mode)
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{
	return sys_fchmodat(AT_FDCWD, filename, mode);
}

525
static int chown_common(struct path *path, uid_t user, gid_t group)
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{
527
	struct inode *inode = path->dentry->d_inode;
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	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))
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		newattrs.ia_valid |=
			ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
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	mutex_lock(&inode->i_mutex);
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	error = security_path_chown(path, user, group);
	if (!error)
		error = notify_change(path->dentry, &newattrs);
547
	mutex_unlock(&inode->i_mutex);
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	return error;
}

552
SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
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{
554
	struct path path;
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	int error;

557
	error = user_path(filename, &path);
558 559
	if (error)
		goto out;
560
	error = mnt_want_write(path.mnt);
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	if (error)
		goto out_release;
563
	error = chown_common(&path, user, group);
564
	mnt_drop_write(path.mnt);
565
out_release:
566
	path_put(&path);
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out:
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	return error;
}

571 572
SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
		gid_t, group, int, flag)
573
{
574
	struct path path;
575
	int error = -EINVAL;
576
	int lookup_flags;
577

578
	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
579 580
		goto out;

581 582 583 584
	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);
585 586
	if (error)
		goto out;
587
	error = mnt_want_write(path.mnt);
588 589
	if (error)
		goto out_release;
590
	error = chown_common(&path, user, group);
591
	mnt_drop_write(path.mnt);
592
out_release:
593
	path_put(&path);
594 595 596 597
out:
	return error;
}

598
SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
L
Linus Torvalds 已提交
599
{
600
	struct path path;
L
Linus Torvalds 已提交
601 602
	int error;

603
	error = user_lpath(filename, &path);
604 605
	if (error)
		goto out;
606
	error = mnt_want_write(path.mnt);
607 608
	if (error)
		goto out_release;
609
	error = chown_common(&path, user, group);
610
	mnt_drop_write(path.mnt);
611
out_release:
612
	path_put(&path);
613
out:
L
Linus Torvalds 已提交
614 615 616
	return error;
}

617
SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
L
Linus Torvalds 已提交
618 619 620
{
	struct file * file;
	int error = -EBADF;
621
	struct dentry * dentry;
L
Linus Torvalds 已提交
622 623

	file = fget(fd);
624 625 626
	if (!file)
		goto out;

N
npiggin@suse.de 已提交
627
	error = mnt_want_write_file(file);
628 629
	if (error)
		goto out_fput;
630
	dentry = file->f_path.dentry;
631
	audit_inode(NULL, dentry);
632
	error = chown_common(&file->f_path, user, group);
633 634
	mnt_drop_write(file->f_path.mnt);
out_fput:
635 636
	fput(file);
out:
L
Linus Torvalds 已提交
637 638 639
	return error;
}

640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668
/*
 * 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;
}

669
static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
670
					struct file *f,
671 672
					int (*open)(struct inode *, struct file *),
					const struct cred *cred)
L
Linus Torvalds 已提交
673
{
674
	static const struct file_operations empty_fops = {};
L
Linus Torvalds 已提交
675 676 677
	struct inode *inode;
	int error;

A
Al Viro 已提交
678
	f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
679
				FMODE_PREAD | FMODE_PWRITE;
680 681 682 683

	if (unlikely(f->f_flags & O_PATH))
		f->f_mode = FMODE_PATH;

L
Linus Torvalds 已提交
684 685
	inode = dentry->d_inode;
	if (f->f_mode & FMODE_WRITE) {
686
		error = __get_file_write_access(inode, mnt);
L
Linus Torvalds 已提交
687 688
		if (error)
			goto cleanup_file;
689 690
		if (!special_file(inode->i_mode))
			file_take_write(f);
L
Linus Torvalds 已提交
691 692 693
	}

	f->f_mapping = inode->i_mapping;
694 695
	f->f_path.dentry = dentry;
	f->f_path.mnt = mnt;
L
Linus Torvalds 已提交
696
	f->f_pos = 0;
N
Nick Piggin 已提交
697
	file_sb_list_add(f, inode->i_sb);
L
Linus Torvalds 已提交
698

699 700 701 702 703 704 705
	if (unlikely(f->f_mode & FMODE_PATH)) {
		f->f_op = &empty_fops;
		return f;
	}

	f->f_op = fops_get(inode->i_fop);

706
	error = security_dentry_open(f, cred);
707 708 709
	if (error)
		goto cleanup_all;

710 711 712 713
	if (!open && f->f_op)
		open = f->f_op->open;
	if (open) {
		error = open(inode, f);
L
Linus Torvalds 已提交
714 715 716
		if (error)
			goto cleanup_all;
	}
717 718
	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
		i_readcount_inc(inode);
719

L
Linus Torvalds 已提交
720 721 722 723 724 725
	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) {
726 727
		if (!f->f_mapping->a_ops ||
		    ((!f->f_mapping->a_ops->direct_IO) &&
728
		    (!f->f_mapping->a_ops->get_xip_mem))) {
L
Linus Torvalds 已提交
729 730 731 732 733 734 735 736 737
			fput(f);
			f = ERR_PTR(-EINVAL);
		}
	}

	return f;

cleanup_all:
	fops_put(f->f_op);
738
	if (f->f_mode & FMODE_WRITE) {
L
Linus Torvalds 已提交
739
		put_write_access(inode);
740 741 742 743 744 745 746 747
		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);
748
			mnt_drop_write(mnt);
749
		}
750
	}
N
Nick Piggin 已提交
751
	file_sb_list_del(f);
752 753
	f->f_path.dentry = NULL;
	f->f_path.mnt = NULL;
L
Linus Torvalds 已提交
754 755 756 757 758 759 760
cleanup_file:
	put_filp(f);
	dput(dentry);
	mntput(mnt);
	return ERR_PTR(error);
}

761 762 763 764 765 766 767 768 769 770
/**
 * 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.
771 772 773 774
 * 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).
775 776 777 778 779 780 781 782
 * 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 *))
{
783 784
	const struct cred *cred = current_cred();

785 786 787 788
	if (IS_ERR(nd->intent.open.file))
		goto out;
	if (IS_ERR(dentry))
		goto out_err;
789
	nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
790
					     nd->intent.open.file,
791
					     open, cred);
792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807
out:
	return nd->intent.open.file;
out_err:
	release_open_intent(nd);
	nd->intent.open.file = (struct file *)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
 */
808
struct file *nameidata_to_filp(struct nameidata *nd)
809
{
810
	const struct cred *cred = current_cred();
811 812 813 814
	struct file *filp;

	/* Pick up the filp from the open intent */
	filp = nd->intent.open.file;
815 816
	nd->intent.open.file = NULL;

817
	/* Has the filesystem initialised the file for us? */
A
Al Viro 已提交
818 819
	if (filp->f_path.dentry == NULL) {
		path_get(&nd->path);
820
		filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp,
821
				     NULL, cred);
A
Al Viro 已提交
822
	}
823 824 825
	return filp;
}

826 827 828 829
/*
 * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
 * error.
 */
830 831
struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
			 const struct cred *cred)
832 833 834 835
{
	int error;
	struct file *f;

836 837
	validate_creds(cred);

838 839 840 841 842 843 844 845 846 847 848 849
	/*
	 * We must always pass in a valid mount pointer.   Historically
	 * callers got away with not passing it, but we must enforce this at
	 * the earliest possible point now to avoid strange problems deep in the
	 * filesystem stack.
	 */
	if (!mnt) {
		printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
		dump_stack();
		return ERR_PTR(-EINVAL);
	}

850 851
	error = -ENFILE;
	f = get_empty_filp();
852 853 854
	if (f == NULL) {
		dput(dentry);
		mntput(mnt);
855
		return ERR_PTR(error);
856
	}
857

858 859
	f->f_flags = flags;
	return __dentry_open(dentry, mnt, f, NULL, cred);
860
}
L
Linus Torvalds 已提交
861 862
EXPORT_SYMBOL(dentry_open);

863
static void __put_unused_fd(struct files_struct *files, unsigned int fd)
L
Linus Torvalds 已提交
864
{
865 866
	struct fdtable *fdt = files_fdtable(files);
	__FD_CLR(fd, fdt->open_fds);
867 868
	if (fd < files->next_fd)
		files->next_fd = fd;
L
Linus Torvalds 已提交
869 870
}

871
void put_unused_fd(unsigned int fd)
L
Linus Torvalds 已提交
872 873 874 875 876 877 878 879 880 881
{
	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);

/*
882
 * Install a file pointer in the fd array.
L
Linus Torvalds 已提交
883 884 885 886 887 888 889 890 891 892 893
 *
 * 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.
 */

894
void fd_install(unsigned int fd, struct file *file)
L
Linus Torvalds 已提交
895 896
{
	struct files_struct *files = current->files;
897
	struct fdtable *fdt;
L
Linus Torvalds 已提交
898
	spin_lock(&files->file_lock);
899
	fdt = files_fdtable(files);
900 901
	BUG_ON(fdt->fd[fd] != NULL);
	rcu_assign_pointer(fdt->fd[fd], file);
L
Linus Torvalds 已提交
902 903 904 905 906
	spin_unlock(&files->file_lock);
}

EXPORT_SYMBOL(fd_install);

907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927
static inline int build_open_flags(int flags, int 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;

928 929 930 931 932 933 934 935 936 937
	/*
	 * 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);
	}
938

939
	op->open_flag = flags;
940 941 942 943 944 945 946 947 948 949 950 951

	/* 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;

952 953
	op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;

954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985
	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, int 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);

A
Al Viro 已提交
986 987 988 989 990 991 992 993 994 995 996 997 998 999
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);

1000
long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
L
Linus Torvalds 已提交
1001
{
1002 1003
	struct open_flags op;
	int lookup = build_open_flags(flags, mode, &op);
1004 1005
	char *tmp = getname(filename);
	int fd = PTR_ERR(tmp);
L
Linus Torvalds 已提交
1006 1007

	if (!IS_ERR(tmp)) {
U
Ulrich Drepper 已提交
1008
		fd = get_unused_fd_flags(flags);
L
Linus Torvalds 已提交
1009
		if (fd >= 0) {
1010
			struct file *f = do_filp_open(dfd, tmp, &op, lookup);
T
Telemaque Ndizihiwe 已提交
1011 1012 1013 1014
			if (IS_ERR(f)) {
				put_unused_fd(fd);
				fd = PTR_ERR(f);
			} else {
1015
				fsnotify_open(f);
T
Telemaque Ndizihiwe 已提交
1016 1017
				fd_install(fd, f);
			}
L
Linus Torvalds 已提交
1018 1019 1020 1021 1022
		}
		putname(tmp);
	}
	return fd;
}
1023

1024
SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, mode)
1025
{
1026 1027
	long ret;

1028 1029 1030
	if (force_o_largefile())
		flags |= O_LARGEFILE;

1031 1032
	ret = do_sys_open(AT_FDCWD, filename, flags, mode);
	/* avoid REGPARM breakage on x86: */
1033
	asmlinkage_protect(3, ret, filename, flags, mode);
1034
	return ret;
1035
}
L
Linus Torvalds 已提交
1036

1037 1038
SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
		int, mode)
1039
{
1040 1041
	long ret;

1042 1043 1044
	if (force_o_largefile())
		flags |= O_LARGEFILE;

1045 1046
	ret = do_sys_open(dfd, filename, flags, mode);
	/* avoid REGPARM breakage on x86: */
1047
	asmlinkage_protect(4, ret, dfd, filename, flags, mode);
1048
	return ret;
1049 1050
}

L
Linus Torvalds 已提交
1051 1052 1053 1054 1055 1056
#ifndef __alpha__

/*
 * For backward compatibility?  Maybe this should be moved
 * into arch/i386 instead?
 */
1057
SYSCALL_DEFINE2(creat, const char __user *, pathname, int, mode)
L
Linus Torvalds 已提交
1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069
{
	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)
{
1070
	int retval = 0;
L
Linus Torvalds 已提交
1071 1072 1073

	if (!file_count(filp)) {
		printk(KERN_ERR "VFS: Close: file count is 0\n");
1074
		return 0;
L
Linus Torvalds 已提交
1075 1076
	}

1077
	if (filp->f_op && filp->f_op->flush)
1078
		retval = filp->f_op->flush(filp, id);
L
Linus Torvalds 已提交
1079

1080 1081 1082 1083
	if (likely(!(filp->f_mode & FMODE_PATH))) {
		dnotify_flush(filp, id);
		locks_remove_posix(filp, id);
	}
L
Linus Torvalds 已提交
1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094
	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.
 */
1095
SYSCALL_DEFINE1(close, unsigned int, fd)
L
Linus Torvalds 已提交
1096 1097 1098
{
	struct file * filp;
	struct files_struct *files = current->files;
1099
	struct fdtable *fdt;
1100
	int retval;
L
Linus Torvalds 已提交
1101 1102

	spin_lock(&files->file_lock);
1103 1104
	fdt = files_fdtable(files);
	if (fd >= fdt->max_fds)
L
Linus Torvalds 已提交
1105
		goto out_unlock;
1106
	filp = fdt->fd[fd];
L
Linus Torvalds 已提交
1107 1108
	if (!filp)
		goto out_unlock;
1109
	rcu_assign_pointer(fdt->fd[fd], NULL);
1110
	FD_CLR(fd, fdt->close_on_exec);
L
Linus Torvalds 已提交
1111 1112
	__put_unused_fd(files, fd);
	spin_unlock(&files->file_lock);
1113 1114 1115 1116 1117 1118 1119 1120 1121 1122
	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;
L
Linus Torvalds 已提交
1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133

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.
 */
1134
SYSCALL_DEFINE0(vhangup)
L
Linus Torvalds 已提交
1135 1136
{
	if (capable(CAP_SYS_TTY_CONFIG)) {
A
Alan Cox 已提交
1137
		tty_vhangup_self();
L
Linus Torvalds 已提交
1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151
		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)
1152
		return -EOVERFLOW;
L
Linus Torvalds 已提交
1153 1154 1155 1156 1157 1158 1159
	return 0;
}

EXPORT_SYMBOL(generic_file_open);

/*
 * This is used by subsystems that don't want seekable
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 * 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.
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 */
int nonseekable_open(struct inode *inode, struct file *filp)
{
	filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
	return 0;
}

EXPORT_SYMBOL(nonseekable_open);