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>

1 files changed, 55 insertions, 16 deletions

diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index feef8a9c4de7..f02404052b7b 100644
--- 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,