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.
Eric Biggers
authored
Some algorithms have a ->setkey() method that is not atomic, in the sense that setting a key can fail after changes were already made to the tfm context. In this case, if a key was already set the tfm can end up in a state that corresponds to neither the old key nor the new key. It's not feasible to make all ->setkey() methods atomic, especially ones that have to key multiple sub-tfms. Therefore, make the crypto API set CRYPTO_TFM_NEED_KEY if ->setkey() fails and the algorithm requires a key, to prevent the tfm from being used until a new key is set. Note: we can't set CRYPTO_TFM_NEED_KEY for OPTIONAL_KEY algorithms, so ->setkey() for those must nevertheless be atomic. That's fine for now since only the crc32 and crc32c algorithms set OPTIONAL_KEY, and it's not intended that OPTIONAL_KEY be used much. [Cc stable mainly because when introducing the NEED_KEY flag I changed AF_ALG to rely on it; and unlike in-kernel crypto API users, AF_ALG previously didn't have this problem. So these "incompletely keyed" states became theoretically accessible via AF_ALG -- though, the opportunities for causing real mischief seem pretty limited.] Fixes: 9fa68f62 ("crypto: hash - prevent using keyed hashes without setting key") Cc: stable@vger.kernel.org Signed-off-by:Eric Biggers <ebiggers@google.com> Signed-off-by:
Herbert Xu <herbert@gondor.apana.org.au>