* Windows October Update Patch Could Affect Symlinks
@ 2021-10-17 17:21 Brian Inglis
2021-10-20 6:55 ` Andrey Repin
0 siblings, 1 reply; 2+ messages in thread
From: Brian Inglis @ 2021-10-17 17:21 UTC (permalink / raw)
To: cygwin
While checking Windows October update patches found a vague reference to
a new Windows update patch affecting symlinks in the article:
https://www.computerworld.com/article/3637013/four-zero-day-exploits-add-urgency-to-octobers-patch-tuesday.html
"On the topic of lesser-used Windows features, the Microsoft NTFS file
system was updated to include a fix for symbolic links (helpful with
UNIX migrations). If you are in the middle of a large UNIX migration,
you may want to pause things a little and test out some large (and
parallel) file transfers before deploying this update."
Could not find anything definite about this patch or its effects or
whether it will create any issues. So this is just a heads up about
potential issues implied by the article. If anyone can find the actual
patch and any docs documenting potential changes or issues that may help.
The article's links to overview and generic articles on NTFS and
symlinks did not help:
https://docs.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/create-symbolic-links#security-considerations
pointing to existing:
https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/fsutil-behavior
On my system, that shows:
Elevated > fsutil behavior set symlinkevaluation /? | grep -E "sym|link"
...
symlinkEvaluation {L2L|L2R|R2R|R2L}:{0|1} [...]
...
Sample SymlinkEvaluation command:
"fsutil behavior set symlinkEvaluation L2L:1 L2R:0"
- Will enable local to local symbolic links and disable local to
remote symbolic links. It will not change the state of remote to
remote links or remote to local links.
- This operation takes effect immediately (no reboot required)
...
Elevated > fsutil behavior query symlinkevaluation
Local to local symbolic links are enabled.
Local to remote symbolic links are enabled.
Remote to local symbolic links are disabled.
Remote to remote symbolic links are disabled.
...
--
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada
This email may be disturbing to some readers as it contains
too much technical detail. Reader discretion is advised.
[Data in binary units and prefixes, physical quantities in SI.]
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Windows October Update Patch Could Affect Symlinks
2021-10-17 17:21 Windows October Update Patch Could Affect Symlinks Brian Inglis
@ 2021-10-20 6:55 ` Andrey Repin
0 siblings, 0 replies; 2+ messages in thread
From: Andrey Repin @ 2021-10-20 6:55 UTC (permalink / raw)
To: Brian Inglis, cygwin
Greetings, Brian Inglis!
> While checking Windows October update patches found a vague reference to
> a new Windows update patch affecting symlinks in the article:
> https://www.computerworld.com/article/3637013/four-zero-day-exploits-add-urgency-to-octobers-patch-tuesday.html
> "On the topic of lesser-used Windows features, the Microsoft NTFS file
> system was updated to include a fix for symbolic links (helpful with
> UNIX migrations). If you are in the middle of a large UNIX migration,
> you may want to pause things a little and test out some large (and
> parallel) file transfers before deploying this update."
> Could not find anything definite about this patch or its effects or
> whether it will create any issues. So this is just a heads up about
> potential issues implied by the article. If anyone can find the actual
> patch and any docs documenting potential changes or issues that may help.
> The article's links to overview and generic articles on NTFS and
> symlinks did not help:
> https://docs.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/create-symbolic-links#security-considerations
> pointing to existing:
> https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/fsutil-behavior
> On my system, that shows:
> Elevated > fsutil behavior set symlinkevaluation /? | grep -E "sym|link"
> ...
> symlinkEvaluation {L2L|L2R|R2R|R2L}:{0|1} [...]
> ...
> Sample SymlinkEvaluation command:
> "fsutil behavior set symlinkEvaluation L2L:1 L2R:0"
> - Will enable local to local symbolic links and disable local to
> remote symbolic links. It will not change the state of remote to
> remote links or remote to local links.
> - This operation takes effect immediately (no reboot required)
> ...
> Elevated > fsutil behavior query symlinkevaluation
> Local to local symbolic links are enabled.
> Local to remote symbolic links are enabled.
> Remote to local symbolic links are disabled.
> Remote to remote symbolic links are disabled.
> ...
This is an old setting and defaults for it are as shown.
If you've never changed them, it's worth checking to make sure they are
untouched. If you did change them at one point, check them to reconsider your
changes.
--
With best regards,
Andrey Repin
Wednesday, October 20, 2021 9:53:38
Sorry for my terrible english...
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