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ba7d7433a0
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: 9fa68f6200 ("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>
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
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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.