docs: Clarify details for reporting security bugs

The kernel security team is regularly asked to provide CVE identifiers,
which we don't normally do. This updates the documentation to mention
this and adds some more details about coordination and patch handling
that come up regularly. Based on an earlier draft by Willy Tarreau.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/admin-guide/security-bugs.rst

@@ -14,14 +14,17 @@ Contact
 The Linux kernel security team can be contacted by email at
 <security@kernel.org>.  This is a private list of security officers
 who will help verify the bug report and develop and release a fix.
-It is possible that the security team will bring in extra help from
-area maintainers to understand and fix the security vulnerability.
+If you already have a fix, please include it with your report, as
+that can speed up the process considerably.  It is possible that the
+security team will bring in extra help from area maintainers to
+understand and fix the security vulnerability.
 
 As it is with any bug, the more information provided the easier it
 will be to diagnose and fix.  Please review the procedure outlined in
-admin-guide/reporting-bugs.rst if you are unclear about what information is helpful.
-Any exploit code is very helpful and will not be released without
-consent from the reporter unless it has already been made public.
+admin-guide/reporting-bugs.rst if you are unclear about what
+information is helpful.  Any exploit code is very helpful and will not
+be released without consent from the reporter unless it has already been
+made public.
 
 Disclosure
 ----------
@@ -39,6 +42,32 @@ disclosure is from immediate (esp. if it's already publicly known)
 to a few weeks.  As a basic default policy, we expect report date to
 disclosure date to be on the order of 7 days.
 
+Coordination
+------------
+
+Fixes for sensitive bugs, such as those that might lead to privilege
+escalations, may need to be coordinated with the private
+<linux-distros@vs.openwall.org> mailing list so that distribution vendors
+are well prepared to issue a fixed kernel upon public disclosure of the
+upstream fix. Distros will need some time to test the proposed patch and
+will generally request at least a few days of embargo, and vendor update
+publication prefers to happen Tuesday through Thursday. When appropriate,
+the security team can assist with this coordination, or the reporter can
+include linux-distros from the start. In this case, remember to prefix
+the email Subject line with "[vs]" as described in the linux-distros wiki:
+<http://oss-security.openwall.org/wiki/mailing-lists/distros#how-to-use-the-lists>
+
+CVE assignment
+--------------
+
+The security team does not normally assign CVEs, nor do we require them
+for reports or fixes, as this can needlessly complicate the process and
+may delay the bug handling. If a reporter wishes to have a CVE identifier
+assigned ahead of public disclosure, they will need to contact the private
+linux-distros list, described above. When such a CVE identifier is known
+before a patch is provided, it is desirable to mention it in the commit
+message, though.
+
 Non-disclosure agreements
 -------------------------