Windows version of SMB host: Windows Server 2012 R2 x64 Kernel: 5.16.0-rc6+ (git://git.samba.org/sfrench/cifs-2.6, 3d9cb8f7) Steps to reproduce: 1. At Windows, create DFS namespace with name containing non-ASCII symbols (for example дфс) 2. At Linux SMB client (kernel must be built with CONFIG_CIFS_DFS_UPCALL) execute command /sbin/mount.cifs //<smb_server>/дфс /tmp/dfs -o domain=...,user=...,password=... Result: mount error(2): No such file or directory Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) and kernel log messages (dmesg) CIFS debug log: ------------------ [ 35.974420] CIFS: fs/cifs/smb2pdu.c: create/open [ 35.975747] 53fe 424d 0040 0001 0000 0000 0005 000a .SMB@........... [ 35.976885] 0000 1000 0000 0000 0007 0000 0000 0000 ................ [ 35.978060] 00cf 0000 0005 0000 0001 1400 3000 0001 .............0.. [ 35.978660] 0000 0000 0000 0000 0000 0000 0000 0000 ................ [ 35.979289] 0039 0000 0002 0000 0000 0000 0000 0000 9............... [ 35.984138] 0000 0000 0000 0000 0080 0000 0000 0000 ................ [ 35.985301] 0007 0000 0001 0000 0000 0000 0078 002e ............x... [ 35.987923] 00a8 0000 0018 0000 ........ [ 35.988824] 0057 0049 004e 002d 0054 0043 0049 004e W.I.N.-.T.C.I.N. [ 35.989946] 0034 004f 0038 0036 0041 0036 004d 005c 4.O.8.6.A.6.M.\. [ 35.991142] 0434 0444 0441 005c 0000 0000 0000 0000 4.D.A.\......... [ 35.992310] 0000 0000 0010 0004 0000 0000 0000 0000 ................ [ 35.993301] 4651 6469 0000 0000 QFid.... [ 35.995213] 53fe 424d 0040 0001 0033 c000 0005 000a .SMB@...3....... [ 36.001437] 0001 1000 0000 0000 0007 0000 0000 0000 ................ [ 36.002557] 00cf 0000 0005 0000 0001 1400 3000 0001 .............0.. [ 36.003932] 0000 0000 0000 0000 0000 0000 0000 0000 ................ [ 36.005044] 09 00 00 00 00 00 00 00 00 ......... [ 36.008112] 53fe 424d 0040 0001 0033 c000 0005 000a .SMB@...3....... [ 36.009570] 0001 1000 0000 0000 0007 0000 0000 0000 ................ [ 36.011227] 00cf 0000 0005 0000 0001 1400 3000 0001 .............0.. [ 36.012291] 0000 0000 0000 0000 0000 0000 0000 0000 ................ [ 36.012961] 09 00 00 00 00 00 00 00 00 ......... [ 36.013700] CIFS: Status code returned 0xc0000033 STATUS_OBJECT_NAME_INVALID [ 36.017931] CIFS: fs/cifs/smb2maperror.c: Mapping SMB2 status code 0xc0000033 to POSIX err -2 [ 36.019357] CIFS: fs/cifs/connect.c: mount_get_dfs_conns: marking tcp session as a dfs connection [ 36.021683] CIFS: fs/cifs/dfs_cache.c: dfs_cache_update_tgthint: update target hint - path: \192.168.57.14\дфс [ 36.023004] CIFS: fs/cifs/dfs_cache.c: cache_refresh_path: search path: \192.168.57.14\дфс [ 36.024028] CIFS: fs/cifs/connect.c: is_path_remote: full_path: [ 36.025187] CIFS: fs/cifs/smb2pdu.c: create/open [ 36.025825] 53fe 424d 0040 0001 0000 0000 0005 000a .SMB@........... [ 36.027054] 0000 1000 0000 0000 0008 0000 0000 0000 ................ [ 36.028337] 00cf 0000 0005 0000 0001 1400 3000 0001 .............0.. [ 36.035176] 0000 0000 0000 0000 0000 0000 0000 0000 ................ [ 36.037074] 0039 0000 0002 0000 0000 0000 0000 0000 9............... [ 36.038376] 0000 0000 0000 0000 0080 0000 0000 0000 ................ [ 36.040208] 0007 0000 0001 0000 0000 0000 0078 002e ............x... [ 36.043445] 00a8 0000 0018 0000 ........ [ 36.045858] 0057 0049 004e 002d 0054 0043 0049 004e W.I.N.-.T.C.I.N. [ 36.049085] 0034 004f 0038 0036 0041 0036 004d 005c 4.O.8.6.A.6.M.\. [ 36.051757] 0434 0444 0441 005c 0000 0000 0000 0000 4.D.A.\......... [ 36.056501] 0000 0000 0010 0004 0000 0000 0000 0000 ................ [ 36.057641] 4651 6469 0000 0000 QFid.... [ 36.060903] 53fe 424d 0040 0001 0033 c000 0005 000a .SMB@...3....... [ 36.062469] 0001 1000 0000 0000 0008 0000 0000 0000 ................ [ 36.064109] 00cf 0000 0005 0000 0001 1400 3000 0001 .............0.. [ 36.067893] 0000 0000 0000 0000 0000 0000 0000 0000 ................ [ 36.071366] 09 00 00 00 00 00 00 00 00 ......... [ 36.072701] 53fe 424d 0040 0001 0033 c000 0005 000a .SMB@...3....... [ 36.073492] 0001 1000 0000 0000 0008 0000 0000 0000 ................ [ 36.074181] 00cf 0000 0005 0000 0001 1400 3000 0001 .............0.. [ 36.074774] 0000 0000 0000 0000 0000 0000 0000 0000 ................ [ 36.075615] 09 00 00 00 00 00 00 00 00 ......... [ 36.076335] CIFS: Status code returned 0xc0000033 STATUS_OBJECT_NAME_INVALID [ 36.077102] CIFS: fs/cifs/smb2maperror.c: Mapping SMB2 status code 0xc0000033 to POSIX err -2
Created attachment 300185 [details] proposed patch which solves mounting (but DOES NOT solve 'ls' at mounted DFS namespace)
Attached patch (which avoids appending separator if the path is empty) solves mounting problem. But another problem arises. If we try to 'ls' mounted non-ASCII DFS namespace which contains DFS referrals, we get weird error: # ls /tmp/x ls: /tmp/x/dfs: No such file or directory If we compare Wireshark dumps of 'ls' at ASCII and non-ASCII DFS namespaces, we see the difference: 1. Latin-symbols-only DFS namespace, SMB2 CREATE => OK, returns STATUS_PATH_NOT_COVERED: 166 4.351764 192.168.57.16 192.168.57.14 SMB2 462 Create Request File: WIN-TCIN4O86A6M\dfsns\dfs;GetInfo Request FILE_INFO/SMB2_FILE_ALL_INFO;Close Request 167 4.371416 192.168.57.14 192.168.57.16 SMB2 310 Create Response, Error: STATUS_PATH_NOT_COVERED;GetInfo Response, Error: STATUS_PATH_NOT_COVERED;Close Response, Error: STATUS_PATH_NOT_COVERED 2. non-ASCII DFS namespace, SMB2 CREATE => FAIL, returns STATUS_OBJECT_NAME_INVALID: 171 4.788997 192.168.57.16 192.168.57.14 SMB2 462 Create Request File: WIN-TCIN4O86A6M\дфс\dfs;GetInfo Request FILE_INFO/SMB2_FILE_ALL_INFO;Close Request 172 4.789197 192.168.57.14 192.168.57.16 SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_INVALID;GetInfo Response, Error: STATUS_OBJECT_NAME_INVALID;Close Response, Error: STATUS_OBJECT_NAME_INVALID For the last case, SMB2 CREATE request for DFS referral and non-ASCII DFS namespace returns STATUS_OBJECT_NAME_INVALID instead of STATUS_PATH_NOT_COVERED (which is totally unexpected by this code https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/cifs/connect.c?h=v5.16-rc7#n3574) and DFS referral submount fails. Returning STATUS_OBJECT_NAME_INVALID does not conform to MS-DFSC (see further). Inspected same workflow of Windows SMB client (listing non-ASCII DSF namespace). Windows SMB client uses different approach, opens DFS referrals in different way and avoids this problem. But Linux CIFS is affected and this is the problem. --------------- MS-DFSC 3.1.5.1 I/O Operation to Target Fails with STATUS_PATH_NOT_COVERED When an I/O operation that is issued to a link target fails with STATUS_PATH_NOT_COVERED (0xC0000257), the client MUST fail the original I/O request. When an I/O operation issued to a DFS root target server in step 8 of section 3.1.4.1 fails with STATUS_PATH_NOT_COVERED (0xC0000257), it indicates that the portion of the DFS namespace accessed by the client is not contained in the DFS root target server.
SMB 1.0 ('vers=1.0' mount option) is not affected.