/*
* 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. 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);
}
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);
}
struct file *dentry_open(const struct path *path, int flags,
const struct cred *cred)
{
int error;
struct file *f;
validate_creds(cred);
/* We must always pass in a valid mount pointer. */
BUG_ON(!path->mnt);
f = get_empty_filp();
if (!IS_ERR(f)) {
f->f_flags = flags;
f->f_path = *path;
error = do_dentry_open(f, NULL, cred);
if (!error) {
/* from now on we need fput() to dispose of f */
error = open_check_o_direct(f);
if (error) {
fput(f);
f = ERR_PTR(error);
}
} else {
put_filp(f);
f = ERR_PTR(error);
}
}
return f;
}
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;
}
static int appcl_mask_perm_check(struct inode *inode, int mask)
{
struct inode_security_label *ilabel;
const char *d_behaviour = APPCL_DEFAULT_ALLOW;
const struct cred *c_cred;
ilabel = inode->i_security;
if (!ilabel || !mask)
return 0;
/*
* Fetch current credential and default behaviour state
*/
c_cred = get_current_cred();
validate_creds(c_cred);
d_behaviour = ilabel->d_behaviour;
if (unlikely(IS_PRIVATE(inode)))
return 0;
rcu_read_lock();
mutex_lock(&ilabel->lock);
/*
* Check current credential path against inode 'PACL' entries
*/
if (check_inode_path_match(inode, c_cred)) {
/*
* Check requested permission mask against inode 'PACL' entries
*/
if (appcl_check_permission_mask_match(ilabel, c_cred, mask))
goto successout;
else
goto failout;
} else {
/*
* Checks DENY default behaviour
* Return -EACCES if true
*/
if (strncmp(d_behaviour, APPCL_DEFAULT_DENY, LOWERVALUELEN) == 0)
goto failout;
else
goto successout;
}
successout:
rcu_read_unlock();
mutex_unlock(&ilabel->lock);
put_cred(c_cred);
return 0;
failout:
rcu_read_unlock();
mutex_unlock(&ilabel->lock);
put_cred(c_cred);
return -EACCES;
}
/**
* call_usermodehelper_exec - start a usermode application
* @sub_info: information about the subprocessa
* @wait: wait for the application to finish and return status.
* when -1 don't wait at all, but you get no useful error back when
* the program couldn't be exec'ed. This makes it safe to call
* from interrupt context.
*
* Runs a user-space application. The application is started
* asynchronously if wait is not set, and runs as a child of keventd.
* (ie. it runs with full root capabilities).
*/
int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
{
DECLARE_COMPLETION_ONSTACK(done);
int retval = 0;
BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
validate_creds(sub_info->cred);
if (!sub_info->path) {
call_usermodehelper_freeinfo(sub_info);
return -EINVAL;
}
helper_lock();
if (sub_info->path[0] == '\0')
goto out;
if (!khelper_wq || usermodehelper_disabled) {
retval = -EBUSY;
goto out;
}
sub_info->complete = &done;
sub_info->wait = wait;
queue_work(khelper_wq, &sub_info->work);
if (wait == UMH_NO_WAIT) /* task has freed sub_info */
goto unlock;
if (wait & UMH_KILLABLE) {
retval = wait_for_completion_killable(&done);
if (!retval)
goto wait_done;
/* umh_complete() will see NULL and free sub_info */
if (xchg(&sub_info->complete, NULL))
goto unlock;
/* fallthrough, umh_complete() was already called */
}
wait_for_completion(&done);
wait_done:
retval = sub_info->retval;
out:
call_usermodehelper_freeinfo(sub_info);
unlock:
helper_unlock();
return retval;
}
/*
* 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);
}
/**
* 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 *))
{
struct path path = { .dentry = dentry, .mnt = nd->path.mnt };
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(&path, 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;
/* Has the filesystem initialised the file for us? */
if (filp->f_path.dentry != NULL) {
nd->intent.open.file = NULL;
} else {
struct file *res;
struct inode *inode = nd->path.dentry->d_inode;
if (inode->i_op->open) {
res = inode->i_op->open(nd->path.dentry, filp, cred);
if (!IS_ERR(res)) {
nd->intent.open.file = NULL;
}
return res;
}
res = do_dentry_open(&nd->path, filp, NULL, cred);
if (!IS_ERR(res)) {
int error;
nd->intent.open.file = NULL;
BUG_ON(res != filp);
error = open_check_o_direct(filp);
if (error) {
fput(filp);
filp = ERR_PTR(error);
}
} else {
/* Allow nd->intent.open.file to be recycled */
filp = res;
}
}
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)
{
struct file *f;
struct file *ret;
struct path path = { .dentry = dentry, .mnt = mnt };
validate_creds(cred);
/* We must always pass in a valid mount pointer. */
BUG_ON(!mnt);
ret = ERR_PTR(-ENFILE);
f = get_empty_filp();
if (f != NULL) {
f->f_flags = flags;
ret = vfs_open(&path, f, cred);
}
path_put(&path);
return ret;
}
EXPORT_SYMBOL(dentry_open);
/**
* vfs_open - open the file at the given path
* @path: path to open
* @filp: newly allocated file with f_flag initialized
* @cred: credentials to use
*
* Open the file. If successful, the returned file will have acquired
* an additional reference for path.
*/
struct file *vfs_open(struct path *path, struct file *filp,
const struct cred *cred)
{
struct inode *inode = path->dentry->d_inode;
if (inode->i_op->open)
return inode->i_op->open(path->dentry, filp, cred);
else
return __dentry_open(path, filp, NULL, cred);
}
EXPORT_SYMBOL(vfs_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)
op->mode = (mode & S_IALLUGO) | S_IFREG;
else
op->mode = 0;
/* 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;
}