cifs: skip trailing separators of prefix paths

During DFS failover, prefix paths may change, so make sure to not
leave trailing separators when parsing thew in
dfs_cache_get_tgt_share().  The separators of prefix paths are already
handled by build_path_from_dentry_optional_prefix().

Consider the following DFS link:

  //dom/dfs/link: [\srv1\share\dir1, \srv2\share\dir1]

Before commit:

  mount.cifs //dom/dfs/link
  tree connect to \\srv1\share; prefix_path=dir1
  disconnect srv1; failover to srv2
  tree connect to \\srv2\share; prefix_path=dir1\
  mv foo bar

  ...
  SMB2 430 Create Request File: dir1\\foo;GetInfo Request FILE_INFO/SMB2_FILE_ALL_INFO;Close Request
  SMB2 582 Create Response File: dir1\\foo;GetInfo Response;Close Response
  SMB2 430 Create Request File: dir1\\bar;GetInfo Request FILE_INFO/SMB2_FILE_ALL_INFO;Close Request
  SMB2 286 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;GetInfo Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;Close Response, Error: STATUS_OBJECT_NAME_NOT_FOUND
  SMB2 462 Create Request File: dir1\\foo;SetInfo Request FILE_INFO/SMB2_FILE_RENAME_INFO NewName:dir1\\bar;Close Request
  SMB2 478 Create Response File: dir1\\foo;SetInfo Response, Error: STATUS_OBJECT_NAME_INVALID;Close Response

After commit:

  mount.cifs //dom/dfs/link
  tree connect to \\srv1\share; prefix_path=dir1
  disconnect srv1; failover to srv2
  tree connect to \\srv2\share; prefix_path=dir1
  mv foo bar

  ...
  SMB2 430 Create Request File: dir1\foo;GetInfo Request FILE_INFO/SMB2_FILE_ALL_INFO;Close Request
  SMB2 582 Create Response File: dir1\foo;GetInfo Response;Close Response
  SMB2 430 Create Request File: dir1\bar;GetInfo Request FILE_INFO/SMB2_FILE_ALL_INFO;Close Request
  SMB2 286 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;GetInfo Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;Close Response, Error: STATUS_OBJECT_NAME_NOT_FOUND
  SMB2 462 Create Request File: dir1\foo;SetInfo Request FILE_INFO/SMB2_FILE_RENAME_INFO NewName:dir1\bar;Close Request
  SMB2 478 Create Response File: dir1\foo;SetInfo Response;Close Response

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c
index aa7d00b5b3e7cccda1da76bee0b1184510b21d19..7b978a1262683b0bff807ffd01225d860ef0642c 100644 (file)
--- a/fs/cifs/dfs_cache.c
+++ b/fs/cifs/dfs_cache.c
@@ -1229,6 +1229,30 @@ void dfs_cache_put_refsrv_sessions(const uuid_t *mount_id)
        kref_put(&mg->refcount, mount_group_release);
 }
 
+/* Extract share from DFS target and return a pointer to prefix path or NULL */
+static const char *parse_target_share(const char *target, char **share)
+{
+       const char *s, *seps = "/\\";
+       size_t len;
+
+       s = strpbrk(target + 1, seps);
+       if (!s)
+               return ERR_PTR(-EINVAL);
+
+       len = strcspn(s + 1, seps);
+       if (!len)
+               return ERR_PTR(-EINVAL);
+       s += len;
+
+       len = s - target + 1;
+       *share = kstrndup(target, len, GFP_KERNEL);
+       if (!*share)
+               return ERR_PTR(-ENOMEM);
+
+       s = target + len;
+       return s + strspn(s, seps);
+}
+
 /**
  * dfs_cache_get_tgt_share - parse a DFS target
  *
@@ -1242,56 +1266,45 @@ void dfs_cache_put_refsrv_sessions(const uuid_t *mount_id)
 int dfs_cache_get_tgt_share(char *path, const struct dfs_cache_tgt_iterator *it, char **share,
                            char **prefix)
 {
-       char *s, sep, *p;
-       size_t len;
-       size_t plen1, plen2;
+       char sep;
+       char *target_share, *ppath;
+       const char *target_ppath, *dfsref_ppath;
+       size_t target_pplen, dfsref_pplen;
+       size_t len, c;
 
        if (!it || !path || !share || !prefix || strlen(path) < it->it_path_consumed)
                return -EINVAL;
 
-       *share = NULL;
-       *prefix = NULL;
-
        sep = it->it_name[0];
        if (sep != '\\' && sep != '/')
                return -EINVAL;
 
-       s = strchr(it->it_name + 1, sep);
-       if (!s)
-               return -EINVAL;
+       target_ppath = parse_target_share(it->it_name, &target_share);
+       if (IS_ERR(target_ppath))
+               return PTR_ERR(target_ppath);
 
-       /* point to prefix in target node */
-       s = strchrnul(s + 1, sep);
+       /* point to prefix in DFS referral path */
+       dfsref_ppath = path + it->it_path_consumed;
+       dfsref_ppath += strspn(dfsref_ppath, "/\\");
 
-       /* extract target share */
-       *share = kstrndup(it->it_name, s - it->it_name, GFP_KERNEL);
-       if (!*share)
-               return -ENOMEM;
+       target_pplen = strlen(target_ppath);
+       dfsref_pplen = strlen(dfsref_ppath);
 
-       /* skip separator */
-       if (*s)
-               s++;
-       /* point to prefix in DFS path */
-       p = path + it->it_path_consumed;
-       if (*p == sep)
-               p++;
-
-       /* merge prefix paths from DFS path and target node */
-       plen1 = it->it_name + strlen(it->it_name) - s;
-       plen2 = path + strlen(path) - p;
-       if (plen1 || plen2) {
-               len = plen1 + plen2 + 2;
-               *prefix = kmalloc(len, GFP_KERNEL);
-               if (!*prefix) {
-                       kfree(*share);
-                       *share = NULL;
+       /* merge prefix paths from DFS referral path and target node */
+       if (target_pplen || dfsref_pplen) {
+               len = target_pplen + dfsref_pplen + 2;
+               ppath = kzalloc(len, GFP_KERNEL);
+               if (!ppath) {
+                       kfree(target_share);
                        return -ENOMEM;
                }
-               if (plen1)
-                       scnprintf(*prefix, len, "%.*s%c%.*s", (int)plen1, s, sep, (int)plen2, p);
-               else
-                       strscpy(*prefix, p, len);
+               c = strscpy(ppath, target_ppath, len);
+               if (c && dfsref_pplen)
+                       ppath[c] = sep;
+               strlcat(ppath, dfsref_ppath, len);
        }
+       *share = target_share;
+       *prefix = ppath;
        return 0;
 }