Re: [PATCH v2 2/2] cifs: quirk for STATUS_OBJECT_NAME_INVALID returned for non-ASCII dfs refs

[Steve French <smfrench@gmail.com>]

tentatively merged into cifs-2.6.git for-next pending more testing

On Fri, Jan 14, 2022 at 5:04 PM Eugene Korenevsky
<ekorenevsky@astralinux.ru> wrote:
>
> Windows SMB server responds with STATUS_OBJECT_NAME_INVALID code to
> SMB2 QUERY_INFO request for "\<server>\<dfsname>\<linkpath>" DFS reference,
> where <dfsname> contains non-ASCII unicode symbols.
>
> Check such DFS reference and emulate -EREMOTE if it is actual.
>
> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=215440
> Signed-off-by: Eugene Korenevsky <ekorenevsky@astralinux.ru>
> ---
> v2: No changes, this is a new patch in the patchset for #215440 fix
>
>  fs/cifs/cifsproto.h |  5 +++++
>  fs/cifs/connect.c   |  5 +++++
>  fs/cifs/inode.c     |  6 ++++++
>  fs/cifs/misc.c      | 49 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 65 insertions(+)
>
> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
> index 4f5a3e857df4..b3a9cc0def2c 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -626,6 +626,11 @@ static inline int get_dfs_path(const unsigned int xid, struct cifs_ses *ses,
>  int match_target_ip(struct TCP_Server_Info *server,
>                     const char *share, size_t share_len,
>                     bool *result);
> +
> +int cifs_dfs_query_info_nonascii_quirk(const unsigned int xid,
> +                                      struct cifs_tcon *tcon,
> +                                      struct cifs_sb_info *cifs_sb,
> +                                      const char *dfs_link_path);
>  #endif
>
>  static inline int cifs_create_options(struct cifs_sb_info *cifs_sb, int options)
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index 1060164b984a..db0f8a1c8fb5 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -3322,6 +3322,11 @@ static int is_path_remote(struct mount_ctx *mnt_ctx)
>
>         rc = server->ops->is_path_accessible(xid, tcon, cifs_sb,
>                                              full_path);
> +#ifdef CONFIG_CIFS_DFS_UPCALL
> +       if (rc == -ENOENT && is_tcon_dfs(tcon))
> +               rc = cifs_dfs_query_info_nonascii_quirk(xid, tcon, cifs_sb,
> +                                                       full_path);
> +#endif
>         if (rc != 0 && rc != -EREMOTE) {
>                 kfree(full_path);
>                 return rc;
> diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
> index 279622e4eb1c..baa197edd8c5 100644
> --- a/fs/cifs/inode.c
> +++ b/fs/cifs/inode.c
> @@ -952,6 +952,12 @@ cifs_get_inode_info(struct inode **inode,
>                 rc = server->ops->query_path_info(xid, tcon, cifs_sb,
>                                                  full_path, tmp_data,
>                                                  &adjust_tz, &is_reparse_point);
> +#ifdef CONFIG_CIFS_DFS_UPCALL
> +               if (rc == -ENOENT && is_tcon_dfs(tcon))
> +                       rc = cifs_dfs_query_info_nonascii_quirk(xid, tcon,
> +                                                               cifs_sb,
> +                                                               full_path);
> +#endif
>                 data = tmp_data;
>         }
>
> diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
> index 5148d48d6a35..56598f7dbe00 100644
> --- a/fs/cifs/misc.c
> +++ b/fs/cifs/misc.c
> @@ -1302,4 +1302,53 @@ int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix)
>         cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
>         return 0;
>  }
> +
> +/** cifs_dfs_query_info_nonascii_quirk
> + * Handle weird Windows SMB server behaviour. It responds with
> + * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request
> + * for "\<server>\<dfsname>\<linkpath>" DFS reference,
> + * where <dfsname> contains non-ASCII unicode symbols.
> + *
> + * Check such DFS reference and emulate -ENOENT if it is actual.
> + */
> +int cifs_dfs_query_info_nonascii_quirk(const unsigned int xid,
> +                                      struct cifs_tcon *tcon,
> +                                      struct cifs_sb_info *cifs_sb,
> +                                      const char *linkpath)
> +{
> +       char *treename, *dfspath, sep;
> +       int treenamelen, linkpathlen, rc;
> +
> +       treename = tcon->treeName;
> +       /* MS-DFSC: All paths in REQ_GET_DFS_REFERRAL and RESP_GET_DFS_REFERRAL
> +        * messages MUST be encoded with exactly one leading backslash, not two
> +        * leading backslashes.
> +        */
> +       sep = CIFS_DIR_SEP(cifs_sb);
> +       if (treename[0] == sep && treename[1] == sep)
> +               treename++;
> +       linkpathlen = strlen(linkpath);
> +       treenamelen = strnlen(treename, MAX_TREE_SIZE + 1);
> +       dfspath = kzalloc(treenamelen + linkpathlen + 1, GFP_KERNEL);
> +       if (!dfspath)
> +               return -ENOMEM;
> +       if (treenamelen)
> +               memcpy(dfspath, treename, treenamelen);
> +       memcpy(dfspath + treenamelen, linkpath, linkpathlen);
> +       rc = dfs_cache_find(xid, tcon->ses, cifs_sb->local_nls,
> +                           cifs_remap(cifs_sb), dfspath, NULL, NULL);
> +       if (rc == 0) {
> +               cifs_dbg(FYI, "DFS ref '%s' is found, emulate -EREMOTE\n",
> +                        dfspath);
> +               rc = -EREMOTE;
> +       } else if (rc == -EEXIST) {
> +               cifs_dbg(FYI, "DFS ref '%s' is not found, emulate -ENOENT\n",
> +                        dfspath);
> +               rc = -ENOENT;
> +       } else {
> +               cifs_dbg(FYI, "%s: dfs_cache_find returned %d\n", __func__, rc);
> +       }
> +       kfree(dfspath);
> +       return rc;
> +}
>  #endif
> --
> 2.30.2
>


-- 
Thanks,

Steve