(This series is based on 14650065b7 (RelNotes/2.48.0: fix typos etc.,
2025-01-07)).
Here is a hopefully final version of my series to harden the unsafe hash
algorithm changes added in v2.47.0. The only difference from last time
is that hash_algo_by_ptr() now returns GIT_HASH_UNKNOWN for NULL and
unsafe variants, which is a strict improvement from both v3 of this
series and the status-quo on master.
As usual, a (small) range-diff is included below for convenience, and
the original cover letter is as follows:
------------
This series implements an idea discussed in [2] which suggests that we
introduce a way to access a wrapped version of a 'struct git_hash_algo'
which represents the unsafe variant of that algorithm, rather than
having individual unsafe_ functions (like unsafe_init_fn() versus
init_fn(), etc.).
This approach is relatively straightforward to implement, and removes a
significant deficiency in the original implementation of
unsafe/non-cryptographic hash functions by making it impossible to
switch between safe- and unsafe variants of hash functions. It also
cleans up the sha1-unsafe test helper's implementation by removing a
large number of "if (unsafe)"-style conditionals.
The series is laid out as follows:
* The first two patches prepare the hashfile API for the upcoming
change:
csum-file: store the hash algorithm as a struct field
csum-file.c: extract algop from hashfile_checksum_valid()
* The next patch implements the new 'unsafe_hash_algo()' function at
the heart of this series' approach:
hash.h: introduce `unsafe_hash_algo()`
* The next two patches convert existing callers to use the new
'unsafe_hash_algo()' function, instead of switching between safe and
unsafe_ variants of individual functions:
csum-file.c: use unsafe_hash_algo()
t/helper/test-hash.c: use unsafe_hash_algo()
* The final patch drops the unsafe_ function variants following all
callers being converted to use the new pattern:
hash.h: drop unsafe_ function variants
Thanks in advance for your review!
[1]: https://lore.kernel.org/git/20241230-pks-meson-sha1-unsafe-v1-0-efb276e171f5@xxxxxx/
[2]: https://lore.kernel.org/git/20241107013915.GA961214@xxxxxxxxxxxxxxxxxxxxxxx/
Taylor Blau (8):
t/helper/test-tool: implement sha1-unsafe helper
csum-file: store the hash algorithm as a struct field
csum-file.c: extract algop from hashfile_checksum_valid()
hash.h: introduce `unsafe_hash_algo()`
csum-file.c: use unsafe_hash_algo()
t/helper/test-hash.c: use unsafe_hash_algo()
csum-file: introduce hashfile_checkpoint_init()
hash.h: drop unsafe_ function variants
builtin/fast-import.c | 2 +-
bulk-checkin.c | 9 ++++++---
csum-file.c | 40 +++++++++++++++++++++++++---------------
csum-file.h | 2 ++
hash.h | 28 ++++++++++++----------------
object-file.c | 41 ++++++++++++++++++++++++++---------------
t/helper/test-hash.c | 4 +++-
t/helper/test-sha1.c | 7 ++++++-
t/helper/test-sha1.sh | 38 ++++++++++++++++++++++----------------
t/helper/test-sha256.c | 2 +-
t/helper/test-tool.c | 1 +
t/helper/test-tool.h | 3 ++-
12 files changed, 107 insertions(+), 70 deletions(-)
Range-diff against v3:
1: ae6b8c75294 = 1: b64ae238248 t/helper/test-tool: implement sha1-unsafe helper
2: 2b79c76e471 = 2: d03f503682f csum-file: store the hash algorithm as a struct field
3: d7deb3f338e = 3: 73554c3b881 csum-file.c: extract algop from hashfile_checksum_valid()
4: b6b2bb2714f ! 4: ae01f1f4274 hash.h: introduce `unsafe_hash_algo()`
@@ hash.h: int hash_algo_by_length(int len);
+ size_t i;
+ for (i = 0; i < GIT_HASH_NALGOS; i++) {
+ const struct git_hash_algo *algop = &hash_algos[i];
-+ if (p == algop || (algop->unsafe && p == algop->unsafe))
++ if (p == algop)
+ return i;
+ }
+ return GIT_HASH_UNKNOWN;
5: ca67de80971 = 5: 64a850c77ae csum-file.c: use unsafe_hash_algo()
6: 21b175b07ff = 6: 3dcccccf752 t/helper/test-hash.c: use unsafe_hash_algo()
7: 850d4f407db = 7: da97157c4a1 csum-file: introduce hashfile_checkpoint_init()
8: 0c4d006e6e8 = 8: 0ba27182b5e hash.h: drop unsafe_ function variants
base-commit: 14650065b76b28d3cfa9453356ac5669b19e706e
--
2.48.0.rc2.35.gd215225db14
