Florian Westphal 2989f1c4c2 netfilter: nf_tables: restrict anonymous set and map names to 16 bytes
[ Upstream commit b462579b2b ]

nftables has two types of sets/maps, one where userspace defines the
name, and anonymous sets/maps, where userspace defines a template name.

For the latter, kernel requires presence of exactly one "%d".
nftables uses "__set%d" and "__map%d" for this.  The kernel will
expand the format specifier and replaces it with the smallest unused
number.

As-is, userspace could define a template name that allows to move
the set name past the 256 bytes upperlimit (post-expansion).

I don't see how this could be a problem, but I would prefer if userspace
cannot do this, so add a limit of 16 bytes for the '%d' template name.

16 bytes is the old total upper limit for set names that existed when
nf_tables was merged initially.

Fixes: 387454901b ("netfilter: nf_tables: Allow set names of up to 255 chars")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-01-31 16:19:03 -08:00
2024-01-25 15:35:41 -08:00
…
…
2024-01-25 15:36:01 -08:00
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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