7984ceb134
We want to leverage keyring to store sensitive keys, and then use those keys for symmetric encryption via the crypto API. Among the key types we wish to support are: user, logon, encrypted, and trusted. User key types are already able to have their data copied to user space, but logon does not support this. Further, trusted and encrypted keys will return their encrypted data back to user space on read, which does not make them ideal for symmetric encryption. To support symmetric encryption for these key types, add a new ALG_SET_KEY_BY_KEY_SERIAL setsockopt() option to the crypto API. This allows users to pass a key_serial_t to the crypto API to perform symmetric encryption. The behavior is the same as ALG_SET_KEY, but the crypto key data is copied in kernel space from a keyring key, which allows for the support of logon, encrypted, and trusted key types. Keyring keys must have the KEY_(POS|USR|GRP|OTH)_SEARCH permission set to leverage this feature. This follows the asymmetric_key type where key lookup calls eventually lead to keyring_search_rcu() without the KEYRING_SEARCH_NO_CHECK_PERM flag set. Signed-off-by: Frederick Lawler <fred@cloudflare.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
``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.