Messages in this thread | | | From | Jonathan Corbet <> | Subject | Re: [PATCH] docs: Makefile: Add -no-shell-escape option to LATEXOPTS | Date | Thu, 10 Feb 2022 10:51:17 -0700 |
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Akira Yokosawa <akiyks@gmail.com> writes:
> By adding this option, message of "restricted \write18 enabled" from > LaTeX can be silenced. > > As there is no use of \write18 in LaTeX sources from sphinx-build, it > is safe to add this option. > > Reported-by: Jonathan Corbet <corbet@lwn.net> > Signed-off-by: Akira Yokosawa <akiyks@gmail.com> > --- > Documentation/Makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/Documentation/Makefile b/Documentation/Makefile > index 9f4bd42cef18..64d44c1ecad3 100644 > --- a/Documentation/Makefile > +++ b/Documentation/Makefile > @@ -26,7 +26,7 @@ SPHINX_CONF = conf.py > PAPER = > BUILDDIR = $(obj)/output > PDFLATEX = xelatex > -LATEXOPTS = -interaction=batchmode > +LATEXOPTS = -interaction=batchmode -no-shell-escape
Interesting. In my digging now and back in 2016 [1] everything I found said that \write18 had to be explicitly enabled - and for good reason. And I could never figure out *how* we were enabling it... It turns out that the net misinformed me; how come nobody ever told me that could happen? :)
Anyway, I've applied this, but I'm going to tweak the changelog a bit. My reason for wanting this isn't to make the warning go away - it's a *tiny* piece of the noise of a pdfdocs build. That warning is there for a reason; \write18 is dangerous. We really don't want any way for arbitrary shell commands to be executed via the docs build. So the new text is:
It turns out that LaTeX enables \write18, which allows arbitrary shell commands to be executed from the document source, by default. This the often-seen warning during a pdfdocs build:
restricted \write18 enabled
That is a potential security problem and is entirely unnecessary; nothing in the kernel PDF docs build needs that capability. So disable \write18 explicitly.
I think I'll add a Cc: stable while I'm at it. I know of no actual threat, but this is best closed.
Thanks for fixing this,
jon
[1] https://lore.kernel.org/lkml/20161113125250.779df4dd@lwn.net/
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