This commit heavily reorganizes the MD5 implementations that exist in
the tree in various aspects.
First, MD5 is added to the list of options available in cryptohash.c and
cryptohash_openssl.c. This means that if building with OpenSSL, EVP is
used for MD5 instead of the fallback implementation that Postgres had
for ages. With the recent refactoring work for cryptohash functions,
this change is straight-forward. If not building with OpenSSL, a
fallback implementation internal to src/common/ is used.
Second, this reduces the number of MD5 implementations present in the
tree from two to one, by moving the KAME implementation from pgcrypto to
src/common/, and by removing the implementation that existed in
src/common/. KAME was already structured with an init/update/final set
of routines by pgcrypto (see original pgcrypto/md5.h) for compatibility
with OpenSSL, so moving it to src/common/ has proved to be a
straight-forward move, requiring no actual manipulation of the internals
of each routine. Some benchmarking has not shown any performance gap
between both implementations.
Similarly to the fallback implementation used for SHA2, the fallback
implementation of MD5 is moved to src/common/md5.c with an internal
header called md5_int.h for the init, update and final routines. This
gets then consumed by cryptohash.c.
The original routines used for MD5-hashed passwords are moved to a
separate file called md5_common.c, also in src/common/, aimed at being
shared between all MD5 implementations as utility routines to keep
compatibility with any code relying on them.
Like the SHA2 changes, this commit had its round of tests on both Linux
and Windows, across all versions of OpenSSL supported on HEAD, with and
even without OpenSSL.
Author: Michael Paquier
Reviewed-by: Daniel Gustafsson
Discussion: https://postgr.es/m/20201106073434.GA4961@paquier.xyz
Two new routines to allocate a hash context and to free it are created,
as these become necessary for the goal behind this refactoring: switch
the all cryptohash implementations for OpenSSL to use EVP (for FIPS and
also because upstream does not recommend the use of low-level cryptohash
functions for 20 years). Note that OpenSSL hides the internals of
cryptohash contexts since 1.1.0, so it is necessary to leave the
allocation to OpenSSL itself, explaining the need for those two new
routines. This part is going to require more work to properly track
hash contexts with resource owners, but this not introduced here.
Still, this refactoring makes the move possible.
This reduces the number of routines for all SHA2 implementations from
twelve (SHA{224,256,386,512} with init, update and final calls) to five
(create, free, init, update and final calls) by incorporating the hash
type directly into the hash context data.
The new cryptohash routines are moved to a new file, called cryptohash.c
for the fallback implementations, with SHA2 specifics becoming a part
internal to src/common/. OpenSSL specifics are part of
cryptohash_openssl.c. This infrastructure is usable for more hash
types, like MD5 or HMAC.
Any code paths using the internal SHA2 routines are adapted to report
correctly errors, which are most of the changes of this commit. The
zones mostly impacted are checksum manifests, libpq and SCRAM.
Note that e21cbb4 was a first attempt to switch SHA2 to EVP, but it
lacked the refactoring needed for libpq, as done here.
This patch has been tested on Linux and Windows, with and without
OpenSSL, and down to 1.0.1, the oldest version supported on HEAD.
Author: Michael Paquier
Reviewed-by: Daniel Gustafsson
Discussion: https://postgr.es/m/20200924025314.GE7405@paquier.xyz
Michael Paquier