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>

diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index feef8a9..f024040 100644 (file)
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -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 @@ out:
        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,