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ecryptfs: fix handling of directory opening 

First of all, trying to open them r/w is idiocy; it's guaranteed to fail.
Moreover, assigning ->f_pos and assuming that everything will work is
blatantly broken - try that with e.g. tmpfs as underlying layer and watch
the fireworks.  There may be a non-trivial amount of state associated with
current IO position, well beyond the numeric offset.  Using the single
struct file associated with underlying inode is really not a good idea;
we ought to open one for each ecryptfs directory struct file.

Additionally, file_operations both for directories and non-directories are
full of pointless methods; non-directories should *not* have ->iterate(),
directories should not have ->flush(), ->fasync() and ->splice_read().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-05-04 14:04:13 -04:00
parent 10c64cea04
commit 6a480a7842
1 changed files with 55 additions and 16 deletions
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71
fs/ecryptfs/file.c
View File

@ -112,7 +112,6 @@ static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
.sb = inode->i_sb,
};
lower_file = ecryptfs_file_to_lower(file);
lower_file->f_pos = ctx->pos;
rc = iterate_dir(lower_file, &buf.ctx);
ctx->pos = buf.ctx.pos;
if (rc < 0)
@ -223,14 +222,6 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
}
ecryptfs_set_file_lower(
file, ecryptfs_inode_to_private(inode)->lower_file);
if (d_is_dir(ecryptfs_dentry)) {
ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
mutex_lock(&crypt_stat->cs_mutex);
crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
mutex_unlock(&crypt_stat->cs_mutex);
rc = 0;
goto out;
}
rc = read_or_initialize_metadata(ecryptfs_dentry);
if (rc)
goto out_put;
@ -247,6 +238,45 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
return rc;
}
/**
* ecryptfs_dir_open
* @inode: inode speciying file to open
* @file: Structure to return filled in
*
* Opens the file specified by inode.
*
* Returns zero on success; non-zero otherwise
*/
static int ecryptfs_dir_open(struct inode *inode, struct file *file)
{
struct dentry *ecryptfs_dentry = file->f_path.dentry;
/* Private value of ecryptfs_dentry allocated in
* ecryptfs_lookup() */
struct ecryptfs_file_info *file_info;
struct file *lower_file;
/* Released in ecryptfs_release or end of function if failure */
file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
ecryptfs_set_file_private(file, file_info);
if (unlikely(!file_info)) {
ecryptfs_printk(KERN_ERR,
"Error attempting to allocate memory\n");
return -ENOMEM;
}
lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry),
file->f_flags, current_cred());
if (IS_ERR(lower_file)) {
printk(KERN_ERR "%s: Error attempting to initialize "
"the lower file for the dentry with name "
"[%pd]; rc = [%ld]\n", __func__,
ecryptfs_dentry, PTR_ERR(lower_file));
kmem_cache_free(ecryptfs_file_info_cache, file_info);
return PTR_ERR(lower_file);
}
ecryptfs_set_file_lower(file, lower_file);
return 0;
}
static int ecryptfs_flush(struct file *file, fl_owner_t td)
{
struct file *lower_file = ecryptfs_file_to_lower(file);
@ -267,6 +297,19 @@ static int ecryptfs_release(struct inode *inode, struct file *file)
return 0;
}
static int ecryptfs_dir_release(struct inode *inode, struct file *file)
{
fput(ecryptfs_file_to_lower(file));
kmem_cache_free(ecryptfs_file_info_cache,
ecryptfs_file_to_private(file));
return 0;
}
static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence)
{
return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence);
}
static int
ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
@ -346,20 +389,16 @@ const struct file_operations ecryptfs_dir_fops = {
#ifdef CONFIG_COMPAT
.compat_ioctl = ecryptfs_compat_ioctl,
#endif
.open = ecryptfs_open,
.flush = ecryptfs_flush,
.release = ecryptfs_release,
.open = ecryptfs_dir_open,
.release = ecryptfs_dir_release,
.fsync = ecryptfs_fsync,
.fasync = ecryptfs_fasync,
.splice_read = generic_file_splice_read,
.llseek = default_llseek,
.llseek = ecryptfs_dir_llseek,
};
const struct file_operations ecryptfs_main_fops = {
.llseek = generic_file_llseek,
.read_iter = ecryptfs_read_update_atime,
.write_iter = generic_file_write_iter,
.iterate = ecryptfs_readdir,
.unlocked_ioctl = ecryptfs_unlocked_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ecryptfs_compat_ioctl,