Documentation: remove current_security() reference

Commit 15322a0d90b6 ("lsm: remove current_security()") removed
current_security() from the sources.

Signed-off-by: Denis Efremov <efremov@linux.com>
Link: https://lore.kernel.org/r/20200830142509.5738-1-efremov@linux.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Security: Documentation: Replace deprecated :c:func: Usage

Replace :c:func: with ``func()`` as the previous usage is deprecated.
Remove an extra ')' to fix broken cross reference.

Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Link: https://lore.kernel.org/r/20200706184956.6928-1-puranjay12@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation: Clarify f_cred vs current_cred() use

When making access control choices from a file-based context, f_cred
must be used instead of current_cred() to avoid confused deputy attacks
where an open file may get passed to a more privileged process. Add a
short paragraph to explicitly state the rationale.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/202007031038.8833A35DE4@keescook
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation: Use "while" instead of "whilst"

Whilst making an unrelated change to some Documentation, Linus sayeth:

| Afaik, even in Britain, "whilst" is unusual and considered more
| formal, and "while" is the common word.
|
| [...]
|
| Can we just admit that we work with computers, and we don't need to
| use þe eald Englisc spelling of words that most of the world never
| uses?

dictionary.com refers to the word as "Chiefly British", which is
probably an undesirable attribute for technical documentation.

Replace all occurrences under Documentation/ with "while".

Cc: David Howells <dhowells@redhat.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michael Halcrow <mhalcrow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation: security/credentials.rst: explain need to sort group_list

This patch updates the documentation with the observations that led
to commit bdcf0a423ea1 ("kernel: make groups_sort calling a
responsibility group_info allocators") and the new behaviour required.
Specifically that groups_sort() should be called on a new group_list
before set_groups() or set_current_groups() is called.

Signed-off-by: NeilBrown <neilb@suse.com>
[jc: use proper :c:func: references]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation: fix security related doc refs

Make security document refs valid.

Signed-off-by: Tom Saeger <tom.saeger@oracle.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

doc: ReSTify credentials.txt

This updates the credentials API documentation to ReST markup and moves
it under the security subsection of kernel API documentation.

Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>