smb3: Allow query of symlinks stored as reparse points

The 'NFS' style symlinks (see MS-FSCC 2.1.2.4) were not
being queried properly in query_symlink. Fix this.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 75f3348..c4047ad 100644 (file)
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -2374,6 +2374,39 @@ smb2_get_dfs_refer(const unsigned int xid, struct cifs_ses *ses,
 }
 
 static int
+parse_reparse_posix(struct reparse_posix_data *symlink_buf,
+                     u32 plen, char **target_path,
+                     struct cifs_sb_info *cifs_sb)
+{
+       unsigned int len;
+
+       /* See MS-FSCC 2.1.2.6 for the 'NFS' style reparse tags */
+       len = le16_to_cpu(symlink_buf->ReparseDataLength);
+
+       if (len + sizeof(struct reparse_data_buffer) > plen) {
+               cifs_dbg(VFS, "srv returned malformed symlink buffer\n");
+               return -EINVAL;
+       }
+
+       if (le64_to_cpu(symlink_buf->InodeType) != NFS_SPECFILE_LNK) {
+               cifs_dbg(VFS, "%lld not a supported symlink type\n",
+                       le64_to_cpu(symlink_buf->InodeType));
+               return -EOPNOTSUPP;
+       }
+
+       *target_path = cifs_strndup_from_utf16(
+                               symlink_buf->PathBuffer,
+                               len, true, cifs_sb->local_nls);
+       if (!(*target_path))
+               return -ENOMEM;
+
+       convert_delimiter(*target_path, '/');
+       cifs_dbg(FYI, "%s: target path: %s\n", __func__, *target_path);
+
+       return 0;
+}
+
+static int
 parse_reparse_symlink(struct reparse_symlink_data_buffer *symlink_buf,
                      u32 plen, char **target_path,
                      struct cifs_sb_info *cifs_sb)
@@ -2381,11 +2414,7 @@ parse_reparse_symlink(struct reparse_symlink_data_buffer *symlink_buf,
        unsigned int sub_len;
        unsigned int sub_offset;
 
-       /* We only handle Symbolic Link : MS-FSCC 2.1.2.4 */
-       if (le32_to_cpu(symlink_buf->ReparseTag) != IO_REPARSE_TAG_SYMLINK) {
-               cifs_dbg(VFS, "srv returned invalid symlink buffer\n");
-               return -EIO;
-       }
+       /* We handle Symbolic Link reparse tag here. See: MS-FSCC 2.1.2.4 */
 
        sub_offset = le16_to_cpu(symlink_buf->SubstituteNameOffset);
        sub_len = le16_to_cpu(symlink_buf->SubstituteNameLength);
@@ -2407,6 +2436,25 @@ parse_reparse_symlink(struct reparse_symlink_data_buffer *symlink_buf,
        return 0;
 }
 
+static int
+parse_reparse_point(struct reparse_symlink_data_buffer *buf,
+                     u32 plen, char **target_path,
+                     struct cifs_sb_info *cifs_sb)
+{
+       /* See MS-FSCC 2.1.2 */
+       if (le32_to_cpu(buf->ReparseTag) == IO_REPARSE_TAG_NFS)
+               return parse_reparse_posix((struct reparse_posix_data *)buf,
+                       plen, target_path, cifs_sb);
+       else if (le32_to_cpu(buf->ReparseTag) == IO_REPARSE_TAG_SYMLINK)
+               return parse_reparse_symlink(buf, plen, target_path,
+                                       cifs_sb);
+
+       cifs_dbg(VFS, "srv returned invalid symlink buffer tag:%d\n",
+               le32_to_cpu(buf->ReparseTag));
+
+       return -EIO;
+}
+
 #define SMB2_SYMLINK_STRUCT_SIZE \
        (sizeof(struct smb2_err_rsp) - 1 + sizeof(struct smb2_symlink_err_rsp))
 
@@ -2547,7 +2595,7 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
                        goto querty_exit;
                }
 
-               rc = parse_reparse_symlink(
+               rc = parse_reparse_point(
                        (struct reparse_symlink_data_buffer *)reparse_buf,
                        plen, target_path, cifs_sb);
                goto querty_exit;