F30 Self-Contained Change proposal: libcrypt.so.1 (compatibility library for POSIX): Let encrypt, encrypt_r, setkey, setkey_r, and fcrypt return ENOSYS instead of performing any real operation

[Ben Cotton]

Remove real functionality from encrypt, encrypt_r, setkey, setkey_r,
and fcrypt from the libxcrypt.so.1 compatibility library and let those
functions set "errno" to "ENOSYS" when invoked.


== Owner ==
* Name: [[User:besser82 | Björn Esser]] <besser82(a)fedoraproject.org&gt;

== Detailed Description ==
In [[Changes/FullyRemoveDeprecatedAndUnsafeFunctionsFromLibcrypt | the
system-wide change: "Fully remove deprecated and unsafe functions from
libcrypt"]] we propose to remove the named functions from the system
default so-version of the crypt library, which is a pre-requirement
for this change.  It basically is a follow-up announcing to remove the
real functionality from those functions in the POSIX-compatibility
version of the crypt library as well, and replace them with fully
POSIX-compilant stubs, that properly indicate those functions are not
supported.

This change was basically filed, because it may require additional
documentation apart from the system-wide change, that is a
pre-requirement for this one.


== Benefit to Fedora ==
Third-party applications, which still use / require these unsafe
functions cannot use them anymore, which is the key benefit of this
change for our users.


== Scope ==
* Proposal owners:  Implement the needed changes in the
libxcrypt-compat package.
* Other developers: N/A (not a System Wide Change)
* Release engineering: N/A, as this is a follow-up of an already
evaluated system-wide change.
* Trademark approval: N/A (not needed for this Change)


== Upgrade/compatibility impact ==
N/A (not a System Wide Change)


== How To Test ==
N/A (not a System Wide Change)


== User Experience ==
No impact, as nothing in the distribution uses those functions.
Third-party applications that are distributed in pre-compiled / binary
form only, may have a reduced set of features.  Since POSIX explicitly
states those functions shall set "errno" to "ENOSYS", if the
functionality is not available nor implemented, third-party
application that start to malfunction are broken by design.


== Dependencies ==
N/A (not a System Wide Change)


== Contingency Plan ==
Revert the change and rebuild libxcrypt.


== Documentation ==
The version of the libcrypt.so.1 library included with Fedora 30 for
POSIX-compatibility has entirely removed the functionality of the
encrypt, encrypt_r, setkey, setkey_r, and fcrypt functions, while
keeping fully binary compatibility with existing (third-party)
applications possibly still using those funtions.  If such an
application attemps to call one of these functions, the corresponding
function will indicate that it is not supported by the system in a
POSIX-compliant way.

All existing binary executables linked against glibc's libcrypt should
work unmodified with this version of the libcrypt.so.1 library
supplied by the libxcrypt-compat package.


== Release Notes ==
See the paragraph about documentation above.


-- 
Ben Cotton
Fedora Program Manager
TZ=America/Indiana/Indianapolis