Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-18 01:51:53 +00:00
Code Issues Packages Projects Releases Wiki Activity
e057ee11ef
linux/fs/open.c
Carsten Otte ceffc07852 [PATCH] xip: fs/mm: execute in place 
- generic_file* file operations do no longer have a xip/non-xip split
- filemap_xip.c implements a new set of fops that require get_xip_page
  aop to work proper. all new fops are exported GPL-only (don't like to
  see whatever code use those except GPL modules)
- __xip_unmap now uses page_check_address, which is no longer static
  in rmap.c, and defined in linux/rmap.h
- mm/filemap.h is now much more clean, plainly having just Linus'
  inline funcs moved here from filemap.c
- fix includes in filemap_xip to make it build cleanly on i386

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-24 00:06:41 -07:00

1068 lines
23 KiB
C
Raw Blame History

/*
* linux/fs/open.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/utime.h>
#include <linux/file.h>
#include <linux/smp_lock.h>
#include <linux/quotaops.h>
#include <linux/dnotify.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/namei.h>
#include <linux/backing-dev.h>
#include <linux/security.h>
#include <linux/mount.h>
#include <linux/vfs.h>
#include <asm/uaccess.h>
#include <linux/fs.h>
#include <linux/personality.h>
#include <linux/pagemap.h>
#include <linux/syscalls.h>
#include <asm/unistd.h>
int vfs_statfs(struct super_block *sb, struct kstatfs *buf)
{
int retval = -ENODEV;
if (sb) {
retval = -ENOSYS;
if (sb->s_op->statfs) {
memset(buf, 0, sizeof(*buf));
retval = security_sb_statfs(sb);
if (retval)
return retval;
retval = sb->s_op->statfs(sb, buf);
if (retval == 0 && buf->f_frsize == 0)
buf->f_frsize = buf->f_bsize;
}
}
return retval;
}
EXPORT_SYMBOL(vfs_statfs);
static int vfs_statfs_native(struct super_block *sb, struct statfs *buf)
{
struct kstatfs st;
int retval;
retval = vfs_statfs(sb, &st);
if (retval)
return retval;
if (sizeof(*buf) == sizeof(st))
memcpy(buf, &st, sizeof(st));
else {
if (sizeof buf->f_blocks == 4) {
if ((st.f_blocks | st.f_bfree | st.f_bavail) &
0xffffffff00000000ULL)
return -EOVERFLOW;
/*
* f_files and f_ffree may be -1; it's okay to stuff
* that into 32 bits
*/
if (st.f_files != -1 &&
(st.f_files & 0xffffffff00000000ULL))
return -EOVERFLOW;
if (st.f_ffree != -1 &&
(st.f_ffree & 0xffffffff00000000ULL))
return -EOVERFLOW;
}
buf->f_type = st.f_type;
buf->f_bsize = st.f_bsize;
buf->f_blocks = st.f_blocks;
buf->f_bfree = st.f_bfree;
buf->f_bavail = st.f_bavail;
buf->f_files = st.f_files;
buf->f_ffree = st.f_ffree;
buf->f_fsid = st.f_fsid;
buf->f_namelen = st.f_namelen;
buf->f_frsize = st.f_frsize;
memset(buf->f_spare, 0, sizeof(buf->f_spare));
}
return 0;
}
static int vfs_statfs64(struct super_block *sb, struct statfs64 *buf)
{
struct kstatfs st;
int retval;
retval = vfs_statfs(sb, &st);
if (retval)
return retval;
if (sizeof(*buf) == sizeof(st))
memcpy(buf, &st, sizeof(st));
else {
buf->f_type = st.f_type;
buf->f_bsize = st.f_bsize;
buf->f_blocks = st.f_blocks;
buf->f_bfree = st.f_bfree;
buf->f_bavail = st.f_bavail;
buf->f_files = st.f_files;
buf->f_ffree = st.f_ffree;
buf->f_fsid = st.f_fsid;
buf->f_namelen = st.f_namelen;
buf->f_frsize = st.f_frsize;
memset(buf->f_spare, 0, sizeof(buf->f_spare));
}
return 0;
}
asmlinkage long sys_statfs(const char __user * path, struct statfs __user * buf)
{
struct nameidata nd;
int error;
error = user_path_walk(path, &nd);
if (!error) {
struct statfs tmp;
error = vfs_statfs_native(nd.dentry->d_inode->i_sb, &tmp);
if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
error = -EFAULT;
path_release(&nd);
}
return error;
}
asmlinkage long sys_statfs64(const char __user *path, size_t sz, struct statfs64 __user *buf)
{
struct nameidata nd;
long error;
if (sz != sizeof(*buf))
return -EINVAL;
error = user_path_walk(path, &nd);
if (!error) {
struct statfs64 tmp;
error = vfs_statfs64(nd.dentry->d_inode->i_sb, &tmp);
if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
error = -EFAULT;
path_release(&nd);
}
return error;
}
asmlinkage long sys_fstatfs(unsigned int fd, struct statfs __user * buf)
{
struct file * file;
struct statfs tmp;
int error;
error = -EBADF;
file = fget(fd);
if (!file)
goto out;
error = vfs_statfs_native(file->f_dentry->d_inode->i_sb, &tmp);
if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
error = -EFAULT;
fput(file);
out:
return error;
}
asmlinkage long sys_fstatfs64(unsigned int fd, size_t sz, struct statfs64 __user *buf)
{
struct file * file;
struct statfs64 tmp;
int error;
if (sz != sizeof(*buf))
return -EINVAL;
error = -EBADF;
file = fget(fd);
if (!file)
goto out;
error = vfs_statfs64(file->f_dentry->d_inode->i_sb, &tmp);
if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
error = -EFAULT;
fput(file);
out:
return error;
}
int do_truncate(struct dentry *dentry, loff_t length)
{
int err;
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 | ATTR_CTIME;
down(&dentry->d_inode->i_sem);
err = notify_change(dentry, &newattrs);
up(&dentry->d_inode->i_sem);
return err;
}
static inline long do_sys_truncate(const char __user * path, loff_t length)
{
struct nameidata nd;
struct inode * inode;
int error;
error = -EINVAL;
if (length < 0) /* sorry, but loff_t says... */
goto out;
error = user_path_walk(path, &nd);
if (error)
goto out;
inode = nd.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 = permission(inode,MAY_WRITE,&nd);
if (error)
goto dput_and_out;
error = -EROFS;
if (IS_RDONLY(inode))
goto dput_and_out;
error = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
goto dput_and_out;
/*
* Make sure that there are no leases.
*/
error = break_lease(inode, FMODE_WRITE);
if (error)
goto dput_and_out;
error = get_write_access(inode);
if (error)
goto dput_and_out;
error = locks_verify_truncate(inode, NULL, length);
if (!error) {
DQUOT_INIT(inode);
error = do_truncate(nd.dentry, length);
}
put_write_access(inode);
dput_and_out:
path_release(&nd);
out:
return error;
}
asmlinkage long sys_truncate(const char __user * path, unsigned long length)
{
/* on 32-bit boxen it will cut the range 2^31--2^32-1 off */
return do_sys_truncate(path, (long)length);
}
static inline 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_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 = do_truncate(dentry, length);
out_putf:
fput(file);
out:
return error;
}
asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length)
{
return do_sys_ftruncate(fd, length, 1);
}
/* LFS versions of truncate are only needed on 32 bit machines */
#if BITS_PER_LONG == 32
asmlinkage long sys_truncate64(const char __user * path, loff_t length)
{
return do_sys_truncate(path, length);
}
asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
{
return do_sys_ftruncate(fd, length, 0);
}
#endif
#ifdef __ARCH_WANT_SYS_UTIME
/*
* sys_utime() can be implemented in user-level using sys_utimes().
* Is this for backwards compatibility? If so, why not move it
* into the appropriate arch directory (for those architectures that
* need it).
*/
/* If times==NULL, set access and modification to current time,
* must be owner or have write permission.
* Else, update from *times, must be owner or super user.
*/
asmlinkage long sys_utime(char __user * filename, struct utimbuf __user * times)
{
int error;
struct nameidata nd;
struct inode * inode;
struct iattr newattrs;
error = user_path_walk(filename, &nd);
if (error)
goto out;
inode = nd.dentry->d_inode;
error = -EROFS;
if (IS_RDONLY(inode))
goto dput_and_out;
/* Don't worry, the checks are done in inode_change_ok() */
newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
if (times) {
error = -EPERM;
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
goto dput_and_out;
error = get_user(newattrs.ia_atime.tv_sec, &times->actime);
newattrs.ia_atime.tv_nsec = 0;
if (!error)
error = get_user(newattrs.ia_mtime.tv_sec, &times->modtime);
newattrs.ia_mtime.tv_nsec = 0;
if (error)
goto dput_and_out;
newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
} else {
error = -EACCES;
if (IS_IMMUTABLE(inode))
goto dput_and_out;
if (current->fsuid != inode->i_uid &&
(error = permission(inode,MAY_WRITE,&nd)) != 0)
goto dput_and_out;
}
down(&inode->i_sem);
error = notify_change(nd.dentry, &newattrs);
up(&inode->i_sem);
dput_and_out:
path_release(&nd);
out:
return error;
}
#endif
/* If times==NULL, set access and modification to current time,
* must be owner or have write permission.
* Else, update from *times, must be owner or super user.
*/
long do_utimes(char __user * filename, struct timeval * times)
{
int error;
struct nameidata nd;
struct inode * inode;
struct iattr newattrs;
error = user_path_walk(filename, &nd);
if (error)
goto out;
inode = nd.dentry->d_inode;
error = -EROFS;
if (IS_RDONLY(inode))
goto dput_and_out;
/* Don't worry, the checks are done in inode_change_ok() */
newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
if (times) {
error = -EPERM;
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
goto dput_and_out;
newattrs.ia_atime.tv_sec = times[0].tv_sec;
newattrs.ia_atime.tv_nsec = times[0].tv_usec * 1000;
newattrs.ia_mtime.tv_sec = times[1].tv_sec;
newattrs.ia_mtime.tv_nsec = times[1].tv_usec * 1000;
newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
} else {
error = -EACCES;
if (IS_IMMUTABLE(inode))
goto dput_and_out;
if (current->fsuid != inode->i_uid &&
(error = permission(inode,MAY_WRITE,&nd)) != 0)
goto dput_and_out;
}
down(&inode->i_sem);
error = notify_change(nd.dentry, &newattrs);
up(&inode->i_sem);
dput_and_out:
path_release(&nd);
out:
return error;
}
asmlinkage long sys_utimes(char __user * filename, struct timeval __user * utimes)
{
struct timeval times[2];
if (utimes && copy_from_user(&times, utimes, sizeof(times)))
return -EFAULT;
return do_utimes(filename, utimes ? times : NULL);
}
/*
* 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.
*/
asmlinkage long sys_access(const char __user * filename, int mode)
{
struct nameidata nd;
int old_fsuid, old_fsgid;
kernel_cap_t old_cap;
int res;
if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
return -EINVAL;
old_fsuid = current->fsuid;
old_fsgid = current->fsgid;
old_cap = current->cap_effective;
current->fsuid = current->uid;
current->fsgid = current->gid;
/*
* Clear the capabilities if we switch to a non-root user
*
* FIXME: There is a race here against sys_capset. The
* capabilities can change yet we will restore the old
* value below. We should hold task_capabilities_lock,
* but we cannot because user_path_walk can sleep.
*/
if (current->uid)
cap_clear(current->cap_effective);
else
current->cap_effective = current->cap_permitted;
res = __user_walk(filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd);
if (!res) {
res = permission(nd.dentry->d_inode, mode, &nd);
/* SuS v2 requires we report a read only fs too */
if(!res && (mode & S_IWOTH) && IS_RDONLY(nd.dentry->d_inode)
&& !special_file(nd.dentry->d_inode->i_mode))
res = -EROFS;
path_release(&nd);
}
current->fsuid = old_fsuid;
current->fsgid = old_fsgid;
current->cap_effective = old_cap;
return res;
}
asmlinkage long sys_chdir(const char __user * filename)
{
struct nameidata nd;
int error;
error = __user_walk(filename, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &nd);
if (error)
goto out;
error = permission(nd.dentry->d_inode,MAY_EXEC,&nd);
if (error)
goto dput_and_out;
set_fs_pwd(current->fs, nd.mnt, nd.dentry);
dput_and_out:
path_release(&nd);
out:
return error;
}
asmlinkage long sys_fchdir(unsigned int fd)
{
struct file *file;
struct dentry *dentry;
struct inode *inode;
struct vfsmount *mnt;
int error;
error = -EBADF;
file = fget(fd);
if (!file)
goto out;
dentry = file->f_dentry;
mnt = file->f_vfsmnt;
inode = dentry->d_inode;
error = -ENOTDIR;
if (!S_ISDIR(inode->i_mode))
goto out_putf;
error = permission(inode, MAY_EXEC, NULL);
if (!error)
set_fs_pwd(current->fs, mnt, dentry);
out_putf:
fput(file);
out:
return error;
}
asmlinkage long sys_chroot(const char __user * filename)
{
struct nameidata nd;
int error;
error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd);
if (error)
goto out;
error = permission(nd.dentry->d_inode,MAY_EXEC,&nd);
if (error)
goto dput_and_out;
error = -EPERM;
if (!capable(CAP_SYS_CHROOT))
goto dput_and_out;
set_fs_root(current->fs, nd.mnt, nd.dentry);
set_fs_altroot();
error = 0;
dput_and_out:
path_release(&nd);
out:
return error;
}
asmlinkage long sys_fchmod(unsigned int fd, mode_t mode)
{
struct inode * inode;
struct dentry * dentry;
struct file * file;
int err = -EBADF;
struct iattr newattrs;
file = fget(fd);
if (!file)
goto out;
dentry = file->f_dentry;
inode = dentry->d_inode;
err = -EROFS;
if (IS_RDONLY(inode))
goto out_putf;
err = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
goto out_putf;
down(&inode->i_sem);
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);
up(&inode->i_sem);
out_putf:
fput(file);
out:
return err;
}
asmlinkage long sys_chmod(const char __user * filename, mode_t mode)
{
struct nameidata nd;
struct inode * inode;
int error;
struct iattr newattrs;
error = user_path_walk(filename, &nd);
if (error)
goto out;
inode = nd.dentry->d_inode;
error = -EROFS;
if (IS_RDONLY(inode))
goto dput_and_out;
error = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
goto dput_and_out;
down(&inode->i_sem);
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;
error = notify_change(nd.dentry, &newattrs);
up(&inode->i_sem);
dput_and_out:
path_release(&nd);
out:
return error;
}
static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
{
struct inode * inode;
int error;
struct iattr newattrs;
error = -ENOENT;
if (!(inode = dentry->d_inode)) {
printk(KERN_ERR "chown_common: NULL inode\n");
goto out;
}
error = -EROFS;
if (IS_RDONLY(inode))
goto out;
error = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
goto out;
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;
down(&inode->i_sem);
error = notify_change(dentry, &newattrs);
up(&inode->i_sem);
out:
return error;
}
asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group)
{
struct nameidata nd;
int error;
error = user_path_walk(filename, &nd);
if (!error) {
error = chown_common(nd.dentry, user, group);
path_release(&nd);
}
return error;
}
asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group)
{
struct nameidata nd;
int error;
error = user_path_walk_link(filename, &nd);
if (!error) {
error = chown_common(nd.dentry, user, group);
path_release(&nd);
}
return error;
}
asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
{
struct file * file;
int error = -EBADF;
file = fget(fd);
if (file) {
error = chown_common(file->f_dentry, user, group);
fput(file);
}
return error;
}
/*
* Note that while the flag value (low two bits) for sys_open means:
* 00 - read-only
* 01 - write-only
* 10 - read-write
* 11 - special
* it is changed into
* 00 - no permissions needed
* 01 - read-permission
* 10 - write-permission
* 11 - read-write
* for the internal routines (ie open_namei()/follow_link() etc). 00 is
* used by symlinks.
*/
struct file *filp_open(const char * filename, int flags, int mode)
{
int namei_flags, error;
struct nameidata nd;
namei_flags = flags;
if ((namei_flags+1) & O_ACCMODE)
namei_flags++;
if (namei_flags & O_TRUNC)
namei_flags |= 2;
error = open_namei(filename, namei_flags, mode, &nd);
if (!error)
return dentry_open(nd.dentry, nd.mnt, flags);
return ERR_PTR(error);
}
EXPORT_SYMBOL(filp_open);
struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
{
struct file * f;
struct inode *inode;
int error;
error = -ENFILE;
f = get_empty_filp();
if (!f)
goto cleanup_dentry;
f->f_flags = flags;
f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
inode = dentry->d_inode;
if (f->f_mode & FMODE_WRITE) {
error = get_write_access(inode);
if (error)
goto cleanup_file;
}
f->f_mapping = inode->i_mapping;
f->f_dentry = dentry;
f->f_vfsmnt = mnt;
f->f_pos = 0;
f->f_op = fops_get(inode->i_fop);
file_move(f, &inode->i_sb->s_files);
if (f->f_op && f->f_op->open) {
error = f->f_op->open(inode,f);
if (error)
goto cleanup_all;
}
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_page))) {
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);
file_kill(f);
f->f_dentry = NULL;
f->f_vfsmnt = NULL;
cleanup_file:
put_filp(f);
cleanup_dentry:
dput(dentry);
mntput(mnt);
return ERR_PTR(error);
}
EXPORT_SYMBOL(dentry_open);
/*
* Find an empty file descriptor entry, and mark it busy.
*/
int get_unused_fd(void)
{
struct files_struct * files = current->files;
int fd, error;
error = -EMFILE;
spin_lock(&files->file_lock);
repeat:
fd = find_next_zero_bit(files->open_fds->fds_bits,
files->max_fdset,
files->next_fd);
/*
* N.B. For clone tasks sharing a files structure, this test
* will limit the total number of files that can be opened.
*/
if (fd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
goto out;
/* Do we need to expand the fd array or fd set? */
error = expand_files(files, fd);
if (error < 0)
goto out;
if (error) {
/*
* If we needed to expand the fs array we
* might have blocked - try again.
*/
error = -EMFILE;
goto repeat;
}
FD_SET(fd, files->open_fds);
FD_CLR(fd, files->close_on_exec);
files->next_fd = fd + 1;
#if 1
/* Sanity check */
if (files->fd[fd] != NULL) {
printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd);
files->fd[fd] = NULL;
}
#endif
error = fd;
out:
spin_unlock(&files->file_lock);
return error;
}
EXPORT_SYMBOL(get_unused_fd);
static inline void __put_unused_fd(struct files_struct *files, unsigned int fd)
{
__FD_CLR(fd, files->open_fds);
if (fd < files->next_fd)
files->next_fd = fd;
}
void fastcall 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 fastcall fd_install(unsigned int fd, struct file * file)
{
struct files_struct *files = current->files;
spin_lock(&files->file_lock);
if (unlikely(files->fd[fd] != NULL))
BUG();
files->fd[fd] = file;
spin_unlock(&files->file_lock);
}
EXPORT_SYMBOL(fd_install);
asmlinkage long sys_open(const char __user * filename, int flags, int mode)
{
char * tmp;
int fd;
if (force_o_largefile())
flags |= O_LARGEFILE;
tmp = getname(filename);
fd = PTR_ERR(tmp);
if (!IS_ERR(tmp)) {
fd = get_unused_fd();
if (fd >= 0) {
struct file *f = filp_open(tmp, flags, mode);
if (IS_ERR(f)) {
put_unused_fd(fd);
fd = PTR_ERR(f);
} else {
fd_install(fd, f);
}
}
putname(tmp);
}
return fd;
}
EXPORT_SYMBOL_GPL(sys_open);
#ifndef __alpha__
/*
* For backward compatibility? Maybe this should be moved
* into arch/i386 instead?
*/
asmlinkage long sys_creat(const char __user * pathname, int 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);
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.
*/
asmlinkage long sys_close(unsigned int fd)
{
struct file * filp;
struct files_struct *files = current->files;
spin_lock(&files->file_lock);
if (fd >= files->max_fds)
goto out_unlock;
filp = files->fd[fd];
if (!filp)
goto out_unlock;
files->fd[fd] = NULL;
FD_CLR(fd, files->close_on_exec);
__put_unused_fd(files, fd);
spin_unlock(&files->file_lock);
return filp_close(filp, files);
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.
*/
asmlinkage long sys_vhangup(void)
{
if (capable(CAP_SYS_TTY_CONFIG)) {
tty_vhangup(current->signal->tty);
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 -EFBIG;
return 0;
}
EXPORT_SYMBOL(generic_file_open);
/*
* This is used by subsystems that don't want seekable
* file descriptors
*/
int nonseekable_open(struct inode *inode, struct file *filp)
{
filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
return 0;
}
EXPORT_SYMBOL(nonseekable_open);
Reference in New Issue View Git Blame Copy Permalink