diff mbox series

[1/2] builddeb: Fix rootless build in setuid/setgid directory

Message ID 20201026193217.402412-1-svenjoac@gmx.de (mailing list archive)
State New
Headers show
Series [1/2] builddeb: Fix rootless build in setuid/setgid directory | expand

Commit Message

Sven Joachim Oct. 26, 2020, 7:32 p.m. UTC
Building 5.10-rc1 in a setgid directory failed with the following
error:

dpkg-deb: error: control directory has bad permissions 2755 (must be
>=0755 and <=0775)

When building with fakeroot, the earlier chown call would have removed
the setgid bits, but in a rootless build they remain.

Fixes: 3e8541803624 ("builddeb: Enable rootless builds")
Cc: Guillem Jover <guillem@hadrons.org>
Signed-off-by: Sven Joachim <svenjoac@gmx.de>
---
 scripts/package/builddeb | 2 ++
 1 file changed, 2 insertions(+)

--
2.28.0

Comments

Masahiro Yamada Oct. 28, 2020, 6 a.m. UTC | #1
On Tue, Oct 27, 2020 at 4:32 AM Sven Joachim <svenjoac@gmx.de> wrote:
>
> Building 5.10-rc1 in a setgid directory failed with the following
> error:
>
> dpkg-deb: error: control directory has bad permissions 2755 (must be
> >=0755 and <=0775)
>
> When building with fakeroot, the earlier chown call would have removed
> the setgid bits, but in a rootless build they remain.
>


Applied to linux-kbuild. Thanks.

I agreed with "g-s" but was not sure about "u-s"
because nothing is explained about setuid,
and the setuid bit against directories seems to have no effect.





It was interesting to read this article:
https://superuser.com/questions/471844/why-is-setuid-ignored-on-directories



Also, it is summarized in the wikipedia
https://en.wikipedia.org/wiki/Setuid#setuid_and_setgid_on_directories

"The setuid permission set on a directory is ignored on most UNIX and
Linux systems.[citation needed] However FreeBSD can be configured to
interpret setuid in a manner similar to setgid, in which case it
forces all files and sub-directories created in a directory to be
owned by that directory's owner - a simple form of inheritance.[5]
This is generally not needed on most systems derived from BSD, since
by default directories are treated as if their setgid bit is always
set, regardless of the actual value. As is stated in open(2), "When a
new file is created it is given the group of the directory which
contains it.""


After all, I am convinced that it would not hurt to do "u-s"
although I have never tested kernel builds on FreeBSD.










> Fixes: 3e8541803624 ("builddeb: Enable rootless builds")
> Cc: Guillem Jover <guillem@hadrons.org>
> Signed-off-by: Sven Joachim <svenjoac@gmx.de>
> ---
>  scripts/package/builddeb | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/scripts/package/builddeb b/scripts/package/builddeb
> index 1b11f8993629..91a502bb97e8 100755
> --- a/scripts/package/builddeb
> +++ b/scripts/package/builddeb
> @@ -45,6 +45,8 @@ create_package() {
>         chmod -R go-w "$pdir"
>         # in case we are in a restrictive umask environment like 0077
>         chmod -R a+rX "$pdir"
> +       # in case we build in a setuid/setgid directory
> +       chmod -R ug-s "$pdir"
>
>         # Create the package
>         dpkg-gencontrol -p$pname -P"$pdir"
> --
> 2.28.0
>


--
Best Regards

Masahiro Yamada
Sven Joachim Oct. 28, 2020, 6:30 p.m. UTC | #2
On 2020-10-28 15:00 +0900, Masahiro Yamada wrote:

> On Tue, Oct 27, 2020 at 4:32 AM Sven Joachim <svenjoac@gmx.de> wrote:
>>
>> Building 5.10-rc1 in a setgid directory failed with the following
>> error:
>>
>> dpkg-deb: error: control directory has bad permissions 2755 (must be
>> >=0755 and <=0775)
>>
>> When building with fakeroot, the earlier chown call would have removed
>> the setgid bits, but in a rootless build they remain.
>>
>
>
> Applied to linux-kbuild. Thanks.

I don't see it there, have you pushed it out yet?

> I agreed with "g-s" but was not sure about "u-s"
> because nothing is explained about setuid,
> and the setuid bit against directories seems to have no effect.
>
>
>
>
>
> It was interesting to read this article:
> https://superuser.com/questions/471844/why-is-setuid-ignored-on-directories
>
>
>
> Also, it is summarized in the wikipedia
> https://en.wikipedia.org/wiki/Setuid#setuid_and_setgid_on_directories
>
> "The setuid permission set on a directory is ignored on most UNIX and
> Linux systems.[citation needed] However FreeBSD can be configured to
> interpret setuid in a manner similar to setgid, in which case it
> forces all files and sub-directories created in a directory to be
> owned by that directory's owner - a simple form of inheritance.[5]
> This is generally not needed on most systems derived from BSD, since
> by default directories are treated as if their setgid bit is always
> set, regardless of the actual value. As is stated in open(2), "When a
> new file is created it is given the group of the directory which
> contains it.""
>
>
> After all, I am convinced that it would not hurt to do "u-s"
> although I have never tested kernel builds on FreeBSD.

Agreed, setuid directories should not end up in the .deb files even if
that bit does currently nothing.

Cheers,
       Sven
diff mbox series

Patch

diff --git a/scripts/package/builddeb b/scripts/package/builddeb
index 1b11f8993629..91a502bb97e8 100755
--- a/scripts/package/builddeb
+++ b/scripts/package/builddeb
@@ -45,6 +45,8 @@  create_package() {
 	chmod -R go-w "$pdir"
 	# in case we are in a restrictive umask environment like 0077
 	chmod -R a+rX "$pdir"
+	# in case we build in a setuid/setgid directory
+	chmod -R ug-s "$pdir"

 	# Create the package
 	dpkg-gencontrol -p$pname -P"$pdir"