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crypto: arm64/chacha - correctly walk through blocks 

Prior, passing in chunks of 2, 3, or 4, followed by any additional
chunks would result in the chacha state counter getting out of sync,
resulting in incorrect encryption/decryption, which is a pretty nasty
crypto vuln: "why do images look weird on webpages?" WireGuard users
never experienced this prior, because we have always, out of tree, used
a different crypto library, until the recent Frankenzinc addition. This
commit fixes the issue by advancing the pointers and state counter by
the actual size processed. It also fixes up a bug in the (optional,
costly) stride test that prevented it from running on arm64.

Fixes: b3aad5bad2 ("crypto: arm64/chacha - expose arm64 ChaCha routine as library function")
Reported-and-tested-by: Emil Renner Berthing <kernel@esmil.dk>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: stable@vger.kernel.org # v5.5+
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Jason A. Donenfeld 2020-03-18 20:27:32 -06:00 committed by Herbert Xu
parent 1579f1bc3b
commit c8cfcb78c6
2 changed files with 12 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/arm64/crypto/chacha-neon-glue.c
View File

@ -55,10 +55,10 @@ static void chacha_doneon(u32 *state, u8 *dst, const u8 *src,
break;
}
chacha_4block_xor_neon(state, dst, src, nrounds, l);
bytes -= CHACHA_BLOCK_SIZE * 5;
src += CHACHA_BLOCK_SIZE * 5;
dst += CHACHA_BLOCK_SIZE * 5;
state[12] += 5;
bytes -= l;
src += l;
dst += l;
state[12] += DIV_ROUND_UP(l, CHACHA_BLOCK_SIZE);
}
}

11
lib/crypto/chacha20poly1305-selftest.c
View File

@ -9028,10 +9028,15 @@ bool __init chacha20poly1305_selftest(void)
&& total_len <= 1 << 10; ++total_len) {
for (i = 0; i <= total_len; ++i) {
for (j = i; j <= total_len; ++j) {
k = 0;
sg_init_table(sg_src, 3);
sg_set_buf(&sg_src[0], input, i);
sg_set_buf(&sg_src[1], input + i, j - i);
sg_set_buf(&sg_src[2], input + j, total_len - j);
if (i)
sg_set_buf(&sg_src[k++], input, i);
if (j - i)
sg_set_buf(&sg_src[k++], input + i, j - i);
if (total_len - j)
sg_set_buf(&sg_src[k++], input + j, total_len - j);
sg_init_marker(sg_src, k);
memset(computed_output, 0, total_len);
memset(input, 0, total_len);