• Stephan Mueller's avatar
    crypto: api - prevent helper ciphers from being used · 06ca7f68
    Stephan Mueller authored
    Several hardware related cipher implementations are implemented as
    follows: a "helper" cipher implementation is registered with the
    kernel crypto API.
    Such helper ciphers are never intended to be called by normal users. In
    some cases, calling them via the normal crypto API may even cause
    failures including kernel crashes. In a normal case, the "wrapping"
    ciphers that use the helpers ensure that these helpers are invoked
    such that they cannot cause any calamity.
    Considering the AF_ALG user space interface, unprivileged users can
    call all ciphers registered with the crypto API, including these
    helper ciphers that are not intended to be called directly. That
    means, with AF_ALG user space may invoke these helper ciphers
    and may cause undefined states or side effects.
    To avoid any potential side effects with such helpers, the patch
    prevents the helpers to be called directly. A new cipher type
    flag is added: CRYPTO_ALG_INTERNAL. This flag shall be used
    to mark helper ciphers. These ciphers can only be used if the
    caller invoke the cipher with CRYPTO_ALG_INTERNAL in the type and
    mask field.
    Signed-off-by: default avatarStephan Mueller <smueller@chronox.de>
    Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
api.c 13.8 KB