os, net/http: avoid escapes from os.DirFS and http.Dir on Windows CVE-2022-41720 #56694
Comments
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@gopherbot please open backport issues. |
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Backport issue(s) opened: #57005 (for 1.18), #57006 (for 1.19). Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases. |
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Change https://go.dev/cl/455362 mentions this issue: |
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Change https://go.dev/cl/455360 mentions this issue: |
… http.Dir on Windows
Do not permit access to Windows reserved device names (NUL, COM1, etc.)
via os.DirFS and http.Dir filesystems.
Avoid escapes from os.DirFS(`\`) on Windows. DirFS would join the
the root to the relative path with a path separator, making
os.DirFS(`\`).Open(`/foo/bar`) open the path `\\foo\bar`, which is
a UNC name. Not only does this not open the intended file, but permits
reference to any file on the system rather than only files on the
current drive.
Make os.DirFS("") invalid, with all file access failing. Previously,
a root of "" was interpreted as "/", which is surprising and probably
unintentional.
Fixes CVE-2022-41720.
Fixes #56694.
Change-Id: I275b5fa391e6ad7404309ea98ccc97405942e0f0
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1663832
Reviewed-by: Julie Qiu <julieqiu@google.com>
Reviewed-by: Tatiana Bradley <tatianabradley@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/455360
Reviewed-by: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Jenny Rakoczy <jenny@golang.org>
… http.Dir on Windows
Do not permit access to Windows reserved device names (NUL, COM1, etc.)
via os.DirFS and http.Dir filesystems.
Avoid escapes from os.DirFS(`\`) on Windows. DirFS would join the
the root to the relative path with a path separator, making
os.DirFS(`\`).Open(`/foo/bar`) open the path `\\foo\bar`, which is
a UNC name. Not only does this not open the intended file, but permits
reference to any file on the system rather than only files on the
current drive.
Make os.DirFS("") invalid, with all file access failing. Previously,
a root of "" was interpreted as "/", which is surprising and probably
unintentional.
Fixes CVE-2022-41720
Fixes #56694
Change-Id: I275b5fa391e6ad7404309ea98ccc97405942e0f0
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1663834
Reviewed-by: Tatiana Bradley <tatianabradley@google.com>
Reviewed-by: Julie Qiu <julieqiu@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/455362
Reviewed-by: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Jenny Rakoczy <jenny@golang.org>
toothrot
changed the title
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Change https://go.dev/cl/455716 mentions this issue: |
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@neild hello,neild. I have a question. You mentioned |
… http.Dir on Windows
Do not permit access to Windows reserved device names (NUL, COM1, etc.)
via os.DirFS and http.Dir filesystems.
Avoid escapes from os.DirFS(`\`) on Windows. DirFS would join the
the root to the relative path with a path separator, making
os.DirFS(`\`).Open(`/foo/bar`) open the path `\\foo\bar`, which is
a UNC name. Not only does this not open the intended file, but permits
reference to any file on the system rather than only files on the
current drive.
Make os.DirFS("") invalid, with all file access failing. Previously,
a root of "" was interpreted as "/", which is surprising and probably
unintentional.
Fixes CVE-2022-41720
Fixes golang#56694
Change-Id: I275b5fa391e6ad7404309ea98ccc97405942e0f0
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1663834
Reviewed-by: Tatiana Bradley <tatianabradley@google.com>
Reviewed-by: Julie Qiu <julieqiu@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/455362
Reviewed-by: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Jenny Rakoczy <jenny@golang.org>
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@neild I would like to point out that the third issue in this CVE is also exploitable on Linux: In addition, the trigger of the second issue as described in the fix commit here is incorrect. and not: May you please revise the phrasing of the GitHub issue and NVD to more clearly indicate this CVE's potential impact on systems other than Windows? |
This is a PRIVATE issue for CVE-2022-41720 tracked in http://b/257275141.
os, net/http: avoid escapes from os.DirFS and http.Dir on Windows
The os.DirFS function and http.Dir type provide access to a tree of files
rooted at a given directory. These functions permitted access to Windows
device files under that root. For example, os.DirFS("C:/tmp").Open("COM1")
would open the COM1 device.
Both os.DirFS and http.Dir only provide read-only filesystem access.
In addition, on Windows, an os.DirFS for the directory
\(the root of thecurrent drive) can permit a maliciously crafted path to escape from the
drive and access any path on the system.
The behavior of os.DirFS("") has changed. Previously, an empty root was
treated equivalently to "/", so os.DirFS("").Open("tmp") would open the path "/tmp".
This now returns an error.
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