CIFS: Fix symbolic links usage

Now we treat any reparse point as a symbolic link and map it to a Unix
one that is not true in a common case due to many reparse point types
supported by SMB servers.

Distinguish reparse point types into two groups:
1) that can be accessed directly through a reparse point
(junctions, deduplicated files, NFS symlinks);
2) that need to be processed manually (Windows symbolic links, DFS);

and map only Windows symbolic links to Unix ones.

Cc: <stable@vger.kernel.org>
Acked-by: Jeff Layton <jlayton@redhat.com>
Reported-and-tested-by: Joao Correia <joaomiguelcorreia@gmail.com>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 13 insertions, 10 deletions

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 867b7cdc794a..36f9ebb93ceb 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -542,7 +542,8 @@ static int cifs_sfu_mode(struct cifs_fattr *fattr, const unsigned char *path,
 /* Fill a cifs_fattr struct with info from FILE_ALL_INFO */
 static void
 cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
-                       struct cifs_sb_info *cifs_sb, bool adjust_tz)
+                       struct cifs_sb_info *cifs_sb, bool adjust_tz,
+                       bool symlink)
 {
         struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
 
@@ -569,7 +570,11 @@ cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
         fattr->cf_createtime = le64_to_cpu(info->CreationTime);
 
         fattr->cf_nlink = le32_to_cpu(info->NumberOfLinks);
-        if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
+
+        if (symlink) {
+                fattr->cf_mode = S_IFLNK;
+                fattr->cf_dtype = DT_LNK;
+        } else if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
                 fattr->cf_mode = S_IFDIR | cifs_sb->mnt_dir_mode;
                 fattr->cf_dtype = DT_DIR;
                 /*
@@ -578,10 +583,6 @@ cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
                  */
                 if (!tcon->unix_ext)
                         fattr->cf_flags |= CIFS_FATTR_UNKNOWN_NLINK;
-        } else if (fattr->cf_cifsattrs & ATTR_REPARSE) {
-                fattr->cf_mode = S_IFLNK;
-                fattr->cf_dtype = DT_LNK;
-                fattr->cf_nlink = le32_to_cpu(info->NumberOfLinks);
         } else {
                 fattr->cf_mode = S_IFREG | cifs_sb->mnt_file_mode;
                 fattr->cf_dtype = DT_REG;
@@ -626,7 +627,8 @@ cifs_get_file_info(struct file *filp)
         rc = server->ops->query_file_info(xid, tcon, &cfile->fid, &find_data);
         switch (rc) {
         case 0:
-                cifs_all_info_to_fattr(&fattr, &find_data, cifs_sb, false);
+                cifs_all_info_to_fattr(&fattr, &find_data, cifs_sb, false,
+                                       false);
                 break;
         case -EREMOTE:
                 cifs_create_dfs_fattr(&fattr, inode->i_sb);
@@ -673,6 +675,7 @@ cifs_get_inode_info(struct inode **inode, const char *full_path,
         bool adjust_tz = false;
         struct cifs_fattr fattr;
         struct cifs_search_info *srchinf = NULL;
+        bool symlink = false;
 
         tlink = cifs_sb_tlink(cifs_sb);
         if (IS_ERR(tlink))
@@ -702,12 +705,12 @@ cifs_get_inode_info(struct inode **inode, const char *full_path,
                 }
                 data = (FILE_ALL_INFO *)buf;
                 rc = server->ops->query_path_info(xid, tcon, cifs_sb, full_path,
-                                                  data, &adjust_tz);
+                                                  data, &adjust_tz, &symlink);
         }
 
         if (!rc) {
-                cifs_all_info_to_fattr(&fattr, (FILE_ALL_INFO *)data, cifs_sb,
-                                       adjust_tz);
+                cifs_all_info_to_fattr(&fattr, data, cifs_sb, adjust_tz,
+                                       symlink);
         } else if (rc == -EREMOTE) {
                 cifs_create_dfs_fattr(&fattr, sb);
                 rc = 0;