[Bug 1854887] Re: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups
This bug was fixed in the package linux - 5.3.0-40.32 --- linux (5.3.0-40.32) eoan; urgency=medium * eoan/linux: 5.3.0-40.32 -proposed tracker (LP: #1861214) * No sof soundcard for 'ASoC: CODEC DAI intel-hdmi-hifi1 not registered' after modprobe sof (LP: #1860248) - ASoC: SOF: Intel: fix HDA codec driver probe with multiple controllers * ocfs2-tools is causing kernel panics in Ubuntu Focal (Ubuntu-5.4.0-9.12) (LP: #1852122) - ocfs2: fix the crash due to call ocfs2_get_dlm_debug once less * QAT drivers for C3XXX and C62X not included as modules (LP: #1845959) - [Config] CRYPTO_DEV_QAT_C3XXX=m, CRYPTO_DEV_QAT_C62X=m and CRYPTO_DEV_QAT_DH895xCC=m * Eoan update: upstream stable patchset 2020-01-24 (LP: #1860816) - scsi: lpfc: Fix discovery failures when target device connectivity bounces - scsi: mpt3sas: Fix clear pending bit in ioctl status - scsi: lpfc: Fix locking on mailbox command completion - Input: atmel_mxt_ts - disable IRQ across suspend - f2fs: fix to update time in lazytime mode - iommu: rockchip: Free domain on .domain_free - iommu/tegra-smmu: Fix page tables in > 4 GiB memory - dmaengine: xilinx_dma: Clear desc_pendingcount in xilinx_dma_reset - scsi: target: compare full CHAP_A Algorithm strings - scsi: lpfc: Fix SLI3 hba in loop mode not discovering devices - scsi: csiostor: Don't enable IRQs too early - scsi: hisi_sas: Replace in_softirq() check in hisi_sas_task_exec() - powerpc/pseries: Mark accumulate_stolen_time() as notrace - powerpc/pseries: Don't fail hash page table insert for bolted mapping - powerpc/tools: Don't quote $objdump in scripts - dma-debug: add a schedule point in debug_dma_dump_mappings() - leds: lm3692x: Handle failure to probe the regulator - clocksource/drivers/asm9260: Add a check for of_clk_get - clocksource/drivers/timer-of: Use unique device name instead of timer - powerpc/security/book3s64: Report L1TF status in sysfs - powerpc/book3s64/hash: Add cond_resched to avoid soft lockup warning - ext4: update direct I/O read lock pattern for IOCB_NOWAIT - ext4: iomap that extends beyond EOF should be marked dirty - jbd2: Fix statistics for the number of logged blocks - scsi: tracing: Fix handling of TRANSFER LENGTH == 0 for READ(6) and WRITE(6) - scsi: lpfc: Fix duplicate unreg_rpi error in port offline flow - f2fs: fix to update dir's i_pino during cross_rename - clk: qcom: Allow constant ratio freq tables for rcg - clk: clk-gpio: propagate rate change to parent - irqchip/irq-bcm7038-l1: Enable parent IRQ if necessary - irqchip: ingenic: Error out if IRQ domain creation failed - fs/quota: handle overflows of sysctl fs.quota.* and report as unsigned long - scsi: lpfc: fix: Coverity: lpfc_cmpl_els_rsp(): Null pointer dereferences - PCI: rpaphp: Fix up pointer to first drc-info entry - scsi: ufs: fix potential bug which ends in system hang - powerpc/pseries/cmm: Implement release() function for sysfs device - PCI: rpaphp: Don't rely on firmware feature to imply drc-info support - PCI: rpaphp: Annotate and correctly byte swap DRC properties - PCI: rpaphp: Correctly match ibm, my-drc-index to drc-name when using drc- info - powerpc/security: Fix wrong message when RFI Flush is disable - scsi: atari_scsi: sun3_scsi: Set sg_tablesize to 1 instead of SG_NONE - clk: pxa: fix one of the pxa RTC clocks - bcache: at least try to shrink 1 node in bch_mca_scan() - HID: quirks: Add quirk for HP MSU1465 PIXART OEM mouse - HID: logitech-hidpp: Silence intermittent get_battery_capacity errors - ARM: 8937/1: spectre-v2: remove Brahma-B53 from hardening - libnvdimm/btt: fix variable 'rc' set but not used - HID: Improve Windows Precision Touchpad detection. - HID: rmi: Check that the RMI_STARTED bit is set before unregistering the RMI transport device - watchdog: Fix the race between the release of watchdog_core_data and cdev - scsi: pm80xx: Fix for SATA device discovery - scsi: ufs: Fix error handing during hibern8 enter - scsi: scsi_debug: num_tgts must be >= 0 - scsi: NCR5380: Add disconnect_mask module parameter - scsi: iscsi: Don't send data to unbound connection - scsi: target: iscsi: Wait for all commands to finish before freeing a session - gpio: mpc8xxx: Don't overwrite default irq_set_type callback - apparmor: fix unsigned len comparison with less than zero - scripts/kallsyms: fix definitely-lost memory leak - powerpc: Don't add -mabi= flags when building with Clang - cdrom: respect device capabilities during opening action - perf script: Fix brstackinsn for AUXTRACE - perf regs: Make perf_reg_name() return "unknown" instead of NULL - s390/zcrypt: handle new reply code FILTERED_BY_HYPERVISOR - libfdt: define INT32_MAX and UINT32_MAX in libfdt_env.h -
[Bug 1854887] Re: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups
Verification for eoan, via the Bionic 5.3 HWE kernel. The customer installed 5.3.0-40-generic #32~18.04.1-Ubuntu to their bionic machine, and mounted their multi-tier cifs share: @:~$ uname -rv 5.3.0-40-generic #32~18.04.1-Ubuntu SMP Mon Feb 3 14:05:59 UTC 2020 @:~$ cd /mnt/share/ @:/mnt/share$ ll total 8 drwxrwxrwx 2 root root 4096 Dec 4 13:36 ./ drwxr-xr-x 3 root root 4096 Dec 4 13:36 ../ @:/mnt/share$ cd / @:/$ sudo mount -v -t cifs //company.com/folders/Country/ -o defaults,user= /mnt/share Password for @//company.com/folders/Country/: *** mount.cifs kernel mount options: ip=,unc=\\company.com\folders,user=,prefixpath=Country/,pass=*** @:/$ cd /mnt/share/ @:/mnt/share$ ll total 4 drwxr-xr-x 2 root root 0 Oct 18 2017 ./ drwxr-xr-x 3 root root 4096 Dec 4 13:36 ../ drwxr-xr-x 2 root root 0 Feb 5 15:39 / drwxr-xr-x 2 root root 0 Feb 4 17:09 / @:/mnt/share$ cd / @:/mnt/share/$ The cifs share mounted successfully, and the user was able to access files in the share. I'm happy to mark this as verified. ** Tags removed: verification-needed-eoan ** Tags added: verification-done-eoan -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1854887 Title: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854887/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1854887] Re: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups
This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed- eoan' to 'verification-done-eoan'. If the problem still exists, change the tag 'verification-needed-eoan' to 'verification-failed-eoan'. If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you! ** Tags added: verification-needed-eoan -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1854887 Title: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854887/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1854887] Re: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups
This bug was fixed in the package linux - 5.0.0-40.44 --- linux (5.0.0-40.44) disco; urgency=medium * disco/linux: 5.0.0-40.44 -proposed tracker (LP: #1859724) * use-after-free in i915_ppgtt_close (LP: #1859522) // CVE-2020-7053 - SAUCE: drm/i915: Fix use-after-free when destroying GEM context * CVE-2019-14615 - drm/i915/gen9: Clear residual context state on context switch * System hang with kernel traces while entering reboot process on a Disco ARM64 moonshot node (LP: #1859582) - Revert "RDMA/cm: Fix memory leak in cm_add/remove_one" linux (5.0.0-39.43) disco; urgency=medium * disco/linux: 5.0.0-39.43 -proposed tracker (LP: #1858547) * [Regression] usb usb2-port2: Cannot enable. Maybe the USB cable is bad? (LP: #1856608) - SAUCE: Revert "usb: handle warm-reset port requests on hub resume" * PAN is broken for execute-only user mappings on ARMv8 (LP: #1858815) - arm64: Revert support for execute-only user mappings * Fix unusable USB hub on Dell TB16 after S3 (LP: #1855312) - SAUCE: USB: core: Make port power cycle a seperate helper function - SAUCE: USB: core: Attempt power cycle port when it's in eSS.Disabled state * [sas-1126]scsi: hisi_sas: Fix out of bound at debug_I_T_nexus_reset() (LP: #1853992) - scsi: hisi_sas: Fix out of bound at debug_I_T_nexus_reset() * [sas-1126]scsi: hisi_sas: Assign NCQ tag for all NCQ commands (LP: #1853995) - scsi: hisi_sas: Assign NCQ tag for all NCQ commands * [sas-1126]scsi: hisi_sas: Fix the conflict between device gone and host reset (LP: #1853997) - scsi: hisi_sas: Fix the conflict between device gone and host reset * scsi: hisi_sas: Check sas_port before using it (LP: #1855952) - scsi: hisi_sas: Check sas_port before using it * CVE-2019-18885 - btrfs: refactor btrfs_find_device() take fs_devices as argument - btrfs: merge btrfs_find_device and find_device * Integrate Intel SGX driver into linux-azure (LP: #1844245) - [Packaging] Add systemd service to load intel_sgx * [SRU][B/OEM-B/OEM-OSP1/D/E/F] Add LG I2C touchscreen multitouch support (LP: #1857541) - SAUCE: HID: multitouch: Add LG MELF0410 I2C touchscreen support * cifs: DFS Caching feature causing problems traversing multi-tier DFS setups (LP: #1854887) - cifs: Fix retrieval of DFS referrals in cifs_mount() * qede driver causes 100% CPU load (LP: #1855409) - qede: Handle infinite driver spinning for Tx timestamp. * [roce-1126]RDMA/hns: bugfix for slab-out-of-bounds when loading hip08 driver (LP: #1853989) - RDMA/hns: Bugfix for slab-out-of-bounds when unloading hip08 driver - RDMA/hns: bugfix for slab-out-of-bounds when loading hip08 driver * [roce-1126]RDMA/hns: Fixs hw access invalid dma memory error (LP: #1853990) - RDMA/hns: Fixs hw access invalid dma memory error * [hns-1126]net: hns3: revert to old channel when setting new channel num fail (LP: #1853983) - net: hns3: revert to old channel when setting new channel num fail * [hns-1126]net: hns3: fix port setting handle for fibre port (LP: #1853984) - net: hns3: fix port setting handle for fibre port * [hns-1126] net: hns: add support for vlan TSO (LP: #1853937) - net: hns: add support for vlan TSO * [hns-1126]net: hns3: fix flow control configure issue for fibre port (LP: #1853948) - net: hns3: fix flow control configure issue for fibre port * mce: ras: When inject 1bit ecc error, there is no mce log recorded in the dmesg (LP: #1857413) - RAS/CEC: Increment cec_entered under the mutex lock - RAS/CEC: Check count_threshold unconditionally * efivarfs test in ubuntu_kernel_selftest failed on the second run (LP: #1809704) - selftests/efivarfs: clean up test files from test_create*() * CVE-2019-19082 - drm/amd/display: prevent memory leak * CVE-2019-19078 - ath10k: fix memory leak * CVE-2019-19077 - RDMA: Fix goto target to release the allocated memory * Disco update: upstream stable patchset 2019-12-17 (LP: #1856754) - rsi: release skb if rsi_prepare_beacon fails - arm64: tegra: Fix 'active-low' warning for Jetson TX1 regulator - sparc64: implement ioremap_uc - lp: fix sparc64 LPSETTIMEOUT ioctl - usb: gadget: u_serial: add missing port entry locking - tty: serial: fsl_lpuart: use the sg count from dma_map_sg - tty: serial: msm_serial: Fix flow control - serial: pl011: Fix DMA ->flush_buffer() - serial: serial_core: Perform NULL checks for break_ctl ops - serial: ifx6x60: add missed pm_runtime_disable - autofs: fix a leak in autofs_expire_indirect() - RDMA/hns: Correct the value of HNS_ROCE_HEM_CHUNK_LEN - iwlwifi: pcie: don't consider IV len in A-MSDU - exportfs_decode_fh(): negative pinned may become positive without the parent locked - audit_get_nd(): don't unlock parent too early - NFC: nxp-nci: Fix NULL pointer
[Bug 1854887] Re: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups
Verification for disco. I went and installed 5.0.0-40-generic from -proposed to a disco box: $ uname -rv 5.0.0-40-generic #44-Ubuntu SMP Wed Jan 15 02:03:45 UTC 2020 I do not have access to a multi tier cifs mount, so I will try and connect to a known one with a bad username / password to ensure that the server forwarding and caching works as expected, since that occurs before authentication. I enabled tracing with: # modprobe cifs # echo 'module cifs +p' > /sys/kernel/debug/dynamic_debug/control # echo 'file fs/cifs/* +p' > /sys/kernel/debug/dynamic_debug/control # echo 7 > /proc/fs/cifs/cifsFYI To mount a cifs share, you need cifs-utils: $ sudo apt install cifs-utils >From there I accessed the multi tier cifs server: $ sudo mount -v -t cifs / -o defaults,user=aaa /mnt/share Checking dmesg we get: Status code returned 0xc257 STATUS_PATH_NOT_COVERED fs/cifs/smb2maperror.c: Mapping SMB2 status code 0xc257 to POSIX err -66 fs/cifs/connect.c: build_unc_path_to_root: full_path=\\\Root\Country\ fs/cifs/connect.c: build_unc_path_to_root: full_path=\\\Root\Country\ fs/cifs/dfs_cache.c: do_dfs_cache_find: search path: \\Root\Country\ fs/cifs/dfs_cache.c: do_dfs_cache_find: cache miss fs/cifs/dfs_cache.c: do_dfs_cache_find: DFS referral request for \\Root\Country\ fs/cifs/smb2ops.c: smb2_get_dfs_refer path <\\Root\Country\> fs/cifs/misc.c: num_referrals: 1 dfs flags: 0x2 ... fs/cifs/dns_resolve.c: dns_resolve_server_name_to_ip: resolved: to fs/cifs/connect.c: Username: aaa This is in line with what is expected, since it resolves the next tier file server instead of failing and going back up the tree. I had also previously supplied the customer with a test build based on the previous bionic hwe kernel, 5.0.0-37-generic #40~18.04.1, with the commit applied, and all was tested and working. With my verification of disco kernel from -proposed the customer's prior test kernel, I am happy to mark this as verified. Next, I just need this patch to land in eoan, and then into a bionic HWE kernel to get this fixed for the customer. ** Tags removed: verification-needed-disco ** Tags added: verification-done-disco -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1854887 Title: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854887/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1854887] Re: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups
This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed- disco' to 'verification-done-disco'. If the problem still exists, change the tag 'verification-needed-disco' to 'verification-failed-disco'. If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you! ** Tags added: verification-needed-disco -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1854887 Title: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854887/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1854887] Re: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups
** Changed in: linux (Ubuntu Eoan) Status: In Progress => Fix Committed ** Changed in: linux (Ubuntu Disco) Status: In Progress => Fix Committed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1854887 Title: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854887/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1854887] Re: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups
This bug was fixed in the package linux - 5.4.0-9.12 --- linux (5.4.0-9.12) focal; urgency=medium * alsa/hda/realtek: the line-out jack doens't work on a dell AIO (LP: #1855999) - SAUCE: ALSA: hda/realtek - Line-out jack doesn't work on a Dell AIO * scsi: hisi_sas: Check sas_port before using it (LP: #1855952) - scsi: hisi_sas: Check sas_port before using it * CVE-2019-19078 - ath10k: fix memory leak * cifs: DFS Caching feature causing problems traversing multi-tier DFS setups (LP: #1854887) - cifs: Fix retrieval of DFS referrals in cifs_mount() * Support DPCD aux brightness control (LP: #1856134) - SAUCE: drm/i915: Fix eDP DPCD aux max backlight calculations - SAUCE: drm/i915: Assume 100% brightness when not in DPCD control mode - SAUCE: drm/i915: Fix DPCD register order in intel_dp_aux_enable_backlight() - SAUCE: drm/i915: Auto detect DPCD backlight support by default - SAUCE: drm/i915: Force DPCD backlight mode on X1 Extreme 2nd Gen 4K AMOLED panel - USUNTU: SAUCE: drm/i915: Force DPCD backlight mode on Dell Precision 4K sku * The system cannot resume from S3 if user unplugs the TB16 during suspend state (LP: #1849269) - PCI: pciehp: Do not disable interrupt twice on suspend - PCI: pciehp: Prevent deadlock on disconnect * change kconfig of the soundwire bus driver from y to m (LP: #1855685) - [Config]: SOUNDWIRE=m * alsa/sof: change to use hda hdmi codec driver to make hdmi audio on the docking station work (LP: #1855666) - ALSA: hda/hdmi - implement mst_no_extra_pcms flag - ASoC: hdac_hda: add support for HDMI/DP as a HDA codec - ASoC: Intel: skl-hda-dsp-generic: use snd-hda-codec-hdmi - ASoC: Intel: skl-hda-dsp-generic: fix include guard name - ASoC: SOF: Intel: add support for snd-hda-codec-hdmi - ASoC: Intel: bxt-da7219-max98357a: common hdmi codec support - ASoC: Intel: glk_rt5682_max98357a: common hdmi codec support - ASoC: intel: sof_rt5682: common hdmi codec support - ASoC: Intel: bxt_rt298: common hdmi codec support - ASoC: SOF: enable sync_write in hdac_bus - [config]: SND_SOC_SOF_HDA_COMMON_HDMI_CODEC=y * Fix unusable USB hub on Dell TB16 after S3 (LP: #1855312) - SAUCE: USB: core: Make port power cycle a seperate helper function - SAUCE: USB: core: Attempt power cycle port when it's in eSS.Disabled state * Focal update: v5.4.3 upstream stable release (LP: #1856583) - rsi: release skb if rsi_prepare_beacon fails - arm64: tegra: Fix 'active-low' warning for Jetson TX1 regulator - arm64: tegra: Fix 'active-low' warning for Jetson Xavier regulator - perf scripts python: exported-sql-viewer.py: Fix use of TRUE with SQLite - sparc64: implement ioremap_uc - lp: fix sparc64 LPSETTIMEOUT ioctl - time: Zero the upper 32-bits in __kernel_timespec on 32-bit - mailbox: tegra: Fix superfluous IRQ error message - staging/octeon: Use stubs for MIPS && !CAVIUM_OCTEON_SOC - usb: gadget: u_serial: add missing port entry locking - serial: 8250-mtk: Use platform_get_irq_optional() for optional irq - tty: serial: fsl_lpuart: use the sg count from dma_map_sg - tty: serial: msm_serial: Fix flow control - serial: pl011: Fix DMA ->flush_buffer() - serial: serial_core: Perform NULL checks for break_ctl ops - serial: stm32: fix clearing interrupt error flags - serial: 8250_dw: Avoid double error messaging when IRQ absent - serial: ifx6x60: add missed pm_runtime_disable - mwifiex: Re-work support for SDIO HW reset - io_uring: fix dead-hung for non-iter fixed rw - io_uring: transform send/recvmsg() -ERESTARTSYS to -EINTR - fuse: fix leak of fuse_io_priv - fuse: verify nlink - fuse: verify write return - fuse: verify attributes - io_uring: fix missing kmap() declaration on powerpc - io_uring: ensure req->submit is copied when req is deferred - SUNRPC: Avoid RPC delays when exiting suspend - ALSA: hda/realtek - Enable internal speaker of ASUS UX431FLC - ALSA: hda/realtek - Fix inverted bass GPIO pin on Acer 8951G - ALSA: pcm: oss: Avoid potential buffer overflows - ALSA: hda - Add mute led support for HP ProBook 645 G4 - ALSA: hda: Modify stream stripe mask only when needed - soc: mediatek: cmdq: fixup wrong input order of write api - Input: synaptics - switch another X1 Carbon 6 to RMI/SMbus - Input: synaptics-rmi4 - re-enable IRQs in f34v7_do_reflash - Input: synaptics-rmi4 - don't increment rmiaddr for SMBus transfers - Input: goodix - add upside-down quirk for Teclast X89 tablet - coresight: etm4x: Fix input validation for sysfs. - Input: Fix memory leak in psxpad_spi_probe - media: rc: mark input device as pointing stick - x86/mm/32: Sync only to VMALLOC_END in vmalloc_sync_all() - CIFS: Fix NULL-pointer dereference in smb2_push_mandatory_locks - CIFS: Fix SMB2 oplock break
[Bug 1854887] Re: cifs: DFS Caching feature causing problems traversing multi-tier DFS setups
** Description changed: BugLink: https://bugs.launchpad.net/bugs/ [Impact] There is a problem where kernels 5.0-rc1 and onwards cannot mount a multi tier cifs DFS setup, while kernels 4.20 and below can mount the share fine. The DFS tiering structure looks like this: Domain virtual DFS (i.e. \\company.com\folders\share) |-- Domain controller DFS (i.e. \\regional-dc.company.com\folders\share) - |-- Regional DFS Server (i.e. \\regional-dfs.company.com\folders\share) - |-- Actual file server (i.e. \\regional-svr.company.com\share) + |-- Regional DFS Server (i.e. \\regional-dfs.company.com\folders\share) + |-- Actual file server (i.e. \\regional-svr.company.com\share) On the 5.x series kernels, after getting the DFS referrals list through to the Regional DFS Server, which responds with the correct server/share, instead of going to the Actual file server, the kernel backtracks from the Regional DFS Server back to the Domain controller and requests the share there. Of course, this share does not exist on the Domain controller, as it only exists on the Actual file server, and the connection dies. We have collected a packet capture, and the flow looks like this: + Legend: + -- + DC = Domain Controller / Domain DFS Root + RDC = Regional Domain Controller / Domain DFS Root + RDS = Regional DFS Server + AFS = Actual File Server + 4.18.0-21-generic Ubuntu kernel - Good - Hostrequest/response - - Domain controller / Domain DFS Root company.com\folders - Domain controller / Domain DFS Root Referral List - Regional Domain Controller / Domain DFS Rootstart convo - Regional Domain Controller / Domain DFS Root\Folders\Country\ referral - Regional Domain Controller / Domain DFS Root\Folders\Country\ referral - Regional DFS server start convo - Regional DFS server \Root\Country\ - Regional DFS server STATUS_PATH_NOT_COVERED - Regional DFS server request referrals - Regional DFS server Referral List - Actual File Server convo started - Actual File Server \ - Actual File Server Good response + Host: request/response + + DC: company.com\folders + DC: Referral List + RDC:start convo + RDC:\Folders\Country\ referral + RDC:\Folders\Country\ referral + RDS:start convo + RDS:\Root\Country\ + RDS:STATUS_PATH_NOT_COVERED + RDS:request referrals + RDS:Referral List + AFS:convo started + AFS:\ + AFS:Good response 5.0.0-26-generic Ubuntu kernel - Bad - Hostrequest/response - --- - Domain controller / Domain DFS Root company.com\folders - Regional Domain Controller / Domain DFS Rootstart convo - Regional Domain Controller / Domain DFS Root\Folders\Country\ - Regional Domain Controller / Domain DFS RootSTATUS_PATH_NOT_COVERED - Regional DFS server start convo - Regional DFS server \Root\Country\ - Regional DFS server STATUS_PATH_NOT_COVERED - Regional Domain Controller / Domain DFS Root\Root\Country\ - Regional Domain Controller / Domain DFS RootSTATUS_PATH_NOT_COVERED + Host: request/response + + DC: company.com\folders + RDC:start convo + RDC:\Folders\Country\ + RDC:STATUS_PATH_NOT_COVERED + RDS:start convo + RDS:\Root\Country\ + RDS:STATUS_PATH_NOT_COVERED + RDC:\Root\Country\ + RDC:STATUS_PATH_NOT_COVERED From there the debugging output was more or less the same between the two kernel versions, until the problematic area: Linux 4.18: Full log: https://paste.ubuntu.com/p/D9XwBbvTXc/ Status code returned 0xc257 STATUS_PATH_NOT_COVERED fs/cifs/smb2maperror.c: Mapping SMB2 status code 0xc257 to POSIX err -66 fs/cifs/connect.c: build_unc_path_to_root: full_path=\\\Root\Country\ fs/cifs/smb2ops.c: smb2_get_dfs_refer path <\\Root\Country\> fs/cifs/misc.c: num_referrals: 1 dfs flags: 0x2 ... fs/cifs/dns_resolve.c: dns_resolve_server_name_to_ip: resolved: to fs/cifs/connect.c: Username: XXX // mounts the share successfully Linux 5.0: Full log: https://paste.ubuntu.com/p/9sXPj7WMQv/ Status code returned 0xc257 STATUS_PATH_NOT_COVERED fs/cifs/smb2maperror.c: Mapping SMB2 status
