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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>
#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"

#define CREATE_TRACE_POINTS
#include <trace/events/fs.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;
}
EXPORT_SYMBOL(do_truncate);

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 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;
if (IS_APPEND(inode))
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)
{
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;

sb_start_write(inode->i_sb);
ret = file->f_op->fallocate(file, mode, offset, len);
sb_end_write(inode->i_sb);
return ret;
}

SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len)
{
struct fd f = fdget(fd);
int error = -EBADF;

if (f.file) {
error = do_fallocate(f.file, mode, offset, len);
fdput(f);
}
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 */
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;
}

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 fd f = fdget_raw(fd);
struct inode *inode;
int error = -EBADF;

error = -EBADF;
if (!f.file)
goto out;

inode = f.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, &f.file->f_path);
out_putf:
fdput(f);
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, 0);
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;
kuid_t uid;
kgid_t gid;

uid = make_kuid(current_user_ns(), user);
gid = make_kgid(current_user_ns(), group);

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;
}
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, uid, gid);
if (!error)
error = notify_change(path->dentry, &newattrs);
mutex_unlock(&inode->i_mutex);

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(chown, const char __user *, filename, uid_t, user, gid_t, group)
{
return sys_fchownat(AT_FDCWD, filename, user, group, 0);
}

SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
{
return sys_fchownat(AT_FDCWD, filename, user, group,
AT_SYMLINK_NOFOLLOW);
}

SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
{
struct fd f = fdget(fd);
int error = -EBADF;

if (!f.file)
goto out;

error = mnt_want_write_file(f.file);
if (error)
goto out_fput;
audit_inode(NULL, f.file->f_path.dentry, 0);
error = chown_common(&f.file->f_path, user, group);
mnt_drop_write_file(f.file);
out_fput:
fdput(f);
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;
}

int open_check_o_direct(struct file *f)
{
/* 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))) {
return -EINVAL;
}
}
return 0;
}

static int do_dentry_open(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;

path_get(&f->f_path);
inode = f->f_path.dentry->d_inode;
if (f->f_mode & FMODE_WRITE) {
error = __get_file_write_access(inode, f->f_path.mnt);
if (error)
goto cleanup_file;
if (!special_file(inode->i_mode))
file_take_write(f);
}

f->f_mapping = inode->i_mapping;
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 0;
}

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

error = security_file_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);

return 0;

cleanup_all:
fops_put(f->f_op);
file_sb_list_del(f);
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(f->f_path.mnt);
}
}
cleanup_file:
path_put(&f->f_path);
f->f_path.mnt = NULL;
f->f_path.dentry = NULL;
return error;
}

/**
* finish_open - finish opening a file
* @od: opaque open data
* @dentry: pointer to dentry
* @open: open callback
*
* 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.
*/
int finish_open(struct file *file, struct dentry *dentry,
int (*open)(struct inode *, struct file *),
int *opened)
{
int error;
BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */

file->f_path.dentry = dentry;
error = do_dentry_open(file, open, current_cred());
if (!error)
*opened |= FILE_OPENED;

return error;
}
EXPORT_SYMBOL(finish_open);

/**
* finish_no_open - finish ->atomic_open() without opening the file
*
* @od: opaque open data
* @dentry: dentry or NULL (as returned from ->lookup())
*
* This can be used to set the result of a successful lookup in ->atomic_open().
* The filesystem's atomic_open() method shall return NULL after calling this.
*/
int finish_no_open(struct file *file, struct dentry *dentry)
{
file->f_path.dentry = dentry;
return 1;
}
EXPORT_SYMBOL(finish_no_open);

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);

error = -ENFILE;
f = get_empty_filp();
if (f == NULL)
return ERR_PTR(error);

f->f_flags = flags;
f->f_path = *path;
error = do_dentry_open(f, NULL, cred);
if (!error) {
error = open_check_o_direct(f);
if (error) {
fput(f);
f = ERR_PTR(error);
}
} else {
put_filp(f);
f = ERR_PTR(error);
}
return f;
}
EXPORT_SYMBOL(dentry_open);

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)
op->mode = (mode & S_IALLUGO) | S_IFREG;
else
op->mode = 0;

/* Must never be set by userspace */
flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC;

/*
* 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;
}

/**
* 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;
int lookup = build_open_flags(flags, mode, &op);
return do_filp_open(AT_FDCWD, name, &op, lookup);
}

/**
* 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 = {.name = filename};
return file_open_name(&name, flags, mode);
}
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);
struct filename *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);
trace_do_sys_open(tmp, flags, mode);
}
}
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)
{
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;
}
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);
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