cifsd: re-implement ksmbd_vfs_kern_path

re-implement ksmbd_vfs_kern_path() to change
recursion to iteration.

Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifsd/vfs.c b/fs/cifsd/vfs.c
index 010dfdd..d8259ca 100644 (file)
--- a/fs/cifsd/vfs.c
+++ b/fs/cifsd/vfs.c
@@ -50,14 +50,6 @@ static char *extract_last_component(char *path)
        return p;
 }
 
-static void rollback_path_modification(char *filename)
-{
-       if (filename) {
-               filename--;
-               *filename = '/';
-       }
-}
-
 static void ksmbd_vfs_inherit_owner(struct ksmbd_work *work,
                struct inode *parent_inode, struct inode *inode)
 {
@@ -1231,44 +1223,32 @@ static int __caseless_lookup(struct dir_context *ctx, const char *name,
 
 /**
  * ksmbd_vfs_lookup_in_dir() - lookup a file in a directory
- * @dirname:   directory name
- * @filename:  filename to lookup
+ * @dir:       path info
+ * @name:      filename to lookup
+ * @namelen:   filename length
  *
  * Return:     0 on success, otherwise error
  */
-static int ksmbd_vfs_lookup_in_dir(char *dirname, char *filename)
+static int ksmbd_vfs_lookup_in_dir(struct path *dir, char *name, size_t namelen)
 {
-       struct path dir_path;
        int ret;
        struct file *dfilp;
        int flags = O_RDONLY | O_LARGEFILE;
-       int dirnamelen = strlen(dirname);
        struct ksmbd_readdir_data readdir_data = {
                .ctx.actor      = __caseless_lookup,
-               .private        = filename,
-               .used           = strlen(filename),
+               .private        = name,
+               .used           = namelen,
+               .dirent_count   = 0,
        };
 
-       ret = ksmbd_vfs_kern_path(dirname, 0, &dir_path, true);
-       if (ret)
-               goto error;
-
-       dfilp = dentry_open(&dir_path, flags, current_cred());
-       if (IS_ERR(dfilp)) {
-               path_put(&dir_path);
-               ksmbd_err("cannot open directory %s\n", dirname);
-               ret = -EINVAL;
-               goto error;
-       }
+       dfilp = dentry_open(dir, flags, current_cred());
+       if (IS_ERR(dfilp))
+               return PTR_ERR(dfilp);
 
        ret = ksmbd_vfs_readdir(dfilp, &readdir_data);
        if (readdir_data.dirent_count > 0)
                ret = 0;
-
        fput(dfilp);
-       path_put(&dir_path);
-error:
-       dirname[dirnamelen] = '/';
        return ret;
 }
 
@@ -1284,30 +1264,69 @@ error:
 int ksmbd_vfs_kern_path(char *name, unsigned int flags, struct path *path,
                bool caseless)
 {
-       char *filename = NULL;
        int err;
 
+       if (name[0] != '/')
+               return -EINVAL;
+
        err = kern_path(name, flags, path);
        if (!err)
-               return err;
+               return 0;
 
        if (caseless) {
-               filename = extract_last_component(name);
-               if (!filename)
-                       goto out;
+               char *filepath;
+               struct path parent;
+               size_t path_len, remain_len;
 
-               /* root reached */
-               if (strlen(name) == 0)
-                       goto out;
+               filepath = kstrdup(name, GFP_KERNEL);
+               if (!filepath)
+                       return -ENOMEM;
+
+               path_len = strlen(filepath);
+               remain_len = path_len - 1;
 
-               err = ksmbd_vfs_lookup_in_dir(name, filename);
+               err = kern_path("/", flags, &parent);
                if (err)
                        goto out;
-               err = kern_path(name, flags, path);
-       }
 
+               while (d_can_lookup(parent.dentry)) {
+                       char *filename = filepath + path_len - remain_len;
+                       char *next = strchrnul(filename, '/');
+                       size_t filename_len = next - filename;
+                       bool is_last = !next[0];
+
+                       if (filename_len == 0)
+                               break;
+
+                       err = ksmbd_vfs_lookup_in_dir(&parent, filename,
+                                                     filename_len);
+                       if (err) {
+                               path_put(&parent);
+                               goto out;
+                       }
+
+                       path_put(&parent);
+                       next[0] = '\0';
+
+                       err = kern_path(filepath, flags, &parent);
+                       if (err)
+                               goto out;
+
+                       if (is_last) {
+                               path->mnt = parent.mnt;
+                               path->dentry = parent.dentry;
+                               goto out;
+                       }
+
+                       next[0] = '/';
+                       remain_len -= filename_len + 1;
+               }
+
+               path_put(&parent);
+               err = -EINVAL;
 out:
-       rollback_path_modification(filename);
+               kfree(filepath);
+       }
        return err;
 }