Bug 2031200

Summary: rename(2) fails on subfolder mounts when the share path has a trailing slash
Product: Red Hat Enterprise Linux 8 Reporter: Thiago Rafael Becker <tbecker>
Component: kernelAssignee: Thiago Rafael Becker <tbecker>
kernel sub component: CIFS QA Contact: xiaoli feng <xifeng>
Status: CLOSED ERRATA Docs Contact:
Severity: urgent    
Priority: unspecified CC: fsorenso, lsahlber, swhiteho, xzhou
Version: 8.5Keywords: CustomerScenariosInitiative, Regression, Reproducer
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: kernel-4.18.0-361.el8 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2022-05-10 15:09:30 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description Thiago Rafael Becker 2021-12-10 18:46:34 UTC
Description of problem:
See 'Steps to reproduce'.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. Export d:\share on windows
2. On linux:
# mount -t cifs -o username=<name> //<host>/share/subfolder/ /mnt

3. Attempt
# mv /mnt/a /mnt/b

Actual results:
mv fails with ENOENT.

Expected results:
No failures.

Additional info:
From the network capture, in kernel-4.18.0-305-19.1.el8_4, we have:
    5   0.018803 → SMB2 458 Create Request File: user\asdf;SetInfo Request FILE_INFO/SMB2_FILE_RENAME_INFO NewName:user\qwer;Close Request
    6   0.027076 →  SMB2 466 Create Response File: user\asdf;SetInfo Response;Close Response

In kernel-4.18.0-348.el8, we have.

    6   0.021708 → SMB2 458 Create Request File: user\\qwer;SetInfo Request FILE_INFO/SMB2_FILE_RENAME_INFO NewName:user\\asdf;Close Request
    7   0.026655 →  SMB2 466 Create Response File: user\\qwer;SetInfo Response, Error: STATUS_OBJECT_NAME_INVALID;Close Response

The path being sent has a double slash in 8.5 that is absent in 8.4.

Comment 2 Frank Sorenson 2021-12-10 19:15:48 UTC
note that samba gets rid of leading, trailing, or multiple sequential '/' or '\\' characters, so this reproducer will require a windows server

Comment 6 Thiago Rafael Becker 2021-12-13 17:19:59 UTC
Tested against rawhide (kernel-5.16.0-0.rc4.20211207gitcd8c917a56f2.30.fc36.x86_64), and it's the same situation.

The patches against cifs between rc4 and rc6 (current upstream) don't show this bug correction.

$ git log --oneline v5.16-rc4..HEAD -- fs/cifs/
9de0737d5ba0 cifs: fix ntlmssp auth when there is no key exchange

So I believe that upstream has this bug.

Also, it seems that any mount where the prepath has more than one '\' between directories is affected, e.g.

# mount -t cifs -o username=user // /mnt
# touch /mnt/a
# mv /mnt/a /mnt/b
mv: cannot move '/mnt/a' to '/mnt/b': No such file or directory

Comment 12 Thiago Rafael Becker 2021-12-17 18:41:06 UTC
v2 of the patch submitted. https://patchwork.kernel.org/project/cifs-client/patch/20211217182022.589857-1-trbecker@gmail.com/

I've found that multiple delimiters between UNC and prepath (//<unc>////<prepath) failed to mount the share. Also, there's a possible memory leak in the code that should be fixed now.

Test script that I've been using.


umount /mnt

echo 7 > /proc/fs/cifs/cifsFYI
echo "func build_path_from_dentry_optional_prefix +p" > /sys/kernel/debug/dynamic_debug/control
dmesg -C

rm -fr /tmp/{cifs.pcap,streams.txt,dmesg.txt}
tcpdump -i eth0 -w /tmp/cifs.pcap host $SERVER &

function testfn {
	echo Testing with DEVICE=$1
	mount -t cifs -o username=$USER,pass="$PASS" $1 /mnt
	touch /mnt/a
	mv /mnt/a /mnt/b
	rm /mnt/a /mnt/b 2>/dev/null
	umount /mnt

testfn $UNC/$PATH1
testfn $UNC//$PATH1
testfn $UNC/$PATH1/
testfn $UNC/$PATH1/$PATH2/
testfn $UNC/$PATH1//$PATH2
testfn $UNC///$PATH1////$PATH2///

echo 0 > /proc/fs/cifs/cifsFYI
echo "func build_path_from_dentry_optional_prefix -p" > /sys/kernel/debug/dynamic_debug/control
kill $tcpdump_pid
dmesg > /tmp/dmesg.txt
for stream in $(tshark -r /tmp/cifs.pcap -Y smb2 -T fields -e tcp.stream | sort -u) ; do
	echo ===== $stream =====
	tshark -r /tmp/cifs.pcap -Y tcp.stream==$stream 
done > /tmp/streams.txt

All tests passing on v2

Comment 13 Thiago Rafael Becker 2021-12-21 16:56:56 UTC
Patch accepted upstream, hash a31080899d5fdafcccf7f39dd214a814a2c82626.
Merge request opened for rhel-8, https://gitlab.com/redhat/rhel/src/kernel/rhel-8/-/merge_requests/1857

Setting the severity. This bug happens on upgrade, under specific conditions, breaking the proper function of systems that where working previously, so I feel like this is good for 'urgent'. Feel free to change it appropriately.

Comment 24 errata-xmlrpc 2022-05-10 15:09:30 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Important: kernel security, bug fix, and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.