From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9AE7EC07E85 for ; Sun, 9 Dec 2018 21:57:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F0F820661 for ; Sun, 9 Dec 2018 21:57:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5F0F820661 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726795AbeLIVzl (ORCPT ); Sun, 9 Dec 2018 16:55:41 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35342 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726539AbeLIVzY (ORCPT ); Sun, 9 Dec 2018 16:55:24 -0500 Received: from pub.yeoldevic.com ([81.174.156.145] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gW72n-0002ij-9g; Sun, 09 Dec 2018 21:55:21 +0000 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gW72k-0003e9-F5; Sun, 09 Dec 2018 21:55:18 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Steve French" , "Paulo Alcantara" , "Ronnie Sahlberg" , "Aurelien Aptel" Date: Sun, 09 Dec 2018 21:50:33 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 291/328] smb2: fix missing files in root share directory listing In-Reply-To: X-SA-Exim-Connect-IP: 81.174.156.145 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.62-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Aurelien Aptel commit 0595751f267994c3c7027377058e4185b3a28e75 upstream. When mounting a Windows share that is the root of a drive (eg. C$) the server does not return . and .. directory entries. This results in the smb2 code path erroneously skipping the 2 first entries. Pseudo-code of the readdir() code path: cifs_readdir(struct file, struct dir_context) initiate_cifs_search <-- if no reponse cached yet server->ops->query_dir_first dir_emit_dots dir_emit <-- adds "." and ".." if we're at pos=0 find_cifs_entry initiate_cifs_search <-- if pos < start of current response (restart search) server->ops->query_dir_next <-- if pos > end of current response (fetch next search res) for(...) <-- loops over cur response entries starting at pos cifs_filldir <-- skip . and .., emit entry cifs_fill_dirent dir_emit pos++ A) dir_emit_dots() always adds . & .. and sets the current dir pos to 2 (0 and 1 are done). Therefore we always want the index_to_find to be 2 regardless of if the response has . and .. B) smb1 code initializes index_of_last_entry with a +2 offset in cifssmb.c CIFSFindFirst(): psrch_inf->index_of_last_entry = 2 /* skip . and .. */ + psrch_inf->entries_in_buffer; Later in find_cifs_entry() we want to find the next dir entry at pos=2 as a result of (A) first_entry_in_buffer = cfile->srch_inf.index_of_last_entry - cfile->srch_inf.entries_in_buffer; This var is the dir pos that the first entry in the buffer will have therefore it must be 2 in the first call. If we don't offset index_of_last_entry by 2 (like in (B)), first_entry_in_buffer=0 but we were instructed to get pos=2 so this code in find_cifs_entry() skips the 2 first which is ok for non-root shares, as it skips . and .. from the response but is not ok for root shares where the 2 first are actual files pos_in_buf = index_to_find - first_entry_in_buffer; // pos_in_buf=2 // we skip 2 first response entries :( for (i = 0; (i < (pos_in_buf)) && (cur_ent != NULL); i++) { /* go entry by entry figuring out which is first */ cur_ent = nxt_dir_entry(cur_ent, end_of_smb, cfile->srch_inf.info_level); } C) cifs_filldir() skips . and .. so we can safely ignore them for now. Sample program: int main(int argc, char **argv) { const char *path = argc >= 2 ? argv[1] : "."; DIR *dh; struct dirent *de; printf("listing path <%s>\n", path); dh = opendir(path); if (!dh) { printf("opendir error %d\n", errno); return 1; } while (1) { de = readdir(dh); if (!de) { if (errno) { printf("readdir error %d\n", errno); return 1; } printf("end of listing\n"); break; } printf("off=%lu <%s>\n", de->d_off, de->d_name); } return 0; } Before the fix with SMB1 on root shares: <.> off=1 <..> off=2 <$Recycle.Bin> off=3 off=4 and on non-root shares: <.> off=1 <..> off=4 <-- after adding .., the offsets jumps to +2 because <2536> off=5 we skipped . and .. from response buffer (C) <411> off=6 but still incremented pos off=7 off=8 Therefore the fix for smb2 is to mimic smb1 behaviour and offset the index_of_last_entry by 2. Test results comparing smb1 and smb2 before/after the fix on root share, non-root shares and on large directories (ie. multi-response dir listing): PRE FIX ======= pre-1-root VS pre-2-root: ERR pre-2-root is missing [bootmgr, $Recycle.Bin] pre-1-nonroot VS pre-2-nonroot: OK~ same files, same order, different offsets pre-1-nonroot-large VS pre-2-nonroot-large: OK~ same files, same order, different offsets POST FIX ======== post-1-root VS post-2-root: OK same files, same order, same offsets post-1-nonroot VS post-2-nonroot: OK same files, same order, same offsets post-1-nonroot-large VS post-2-nonroot-large: OK same files, same order, same offsets REGRESSION? =========== pre-1-root VS post-1-root: OK same files, same order, same offsets pre-1-nonroot VS post-1-nonroot: OK same files, same order, same offsets BugLink: https://bugzilla.samba.org/show_bug.cgi?id=13107 Signed-off-by: Aurelien Aptel Signed-off-by: Paulo Alcantara Reviewed-by: Ronnie Sahlberg Signed-off-by: Steve French Signed-off-by: Ben Hutchings --- fs/cifs/smb2ops.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -743,7 +743,7 @@ smb2_query_dir_first(const unsigned int } srch_inf->entries_in_buffer = 0; - srch_inf->index_of_last_entry = 0; + srch_inf->index_of_last_entry = 2; rc = SMB2_query_directory(xid, tcon, fid->persistent_fid, fid->volatile_fid, 0, srch_inf);