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: b3aad5b ("crypto: arm64/chacha - expose arm64 ChaCha routine as library function") Reported-and-tested-by: Emil Renner Berthing <[email protected]> Cc: Ard Biesheuvel <[email protected]> Cc: [email protected] # v5.5+ Signed-off-by: Jason A. Donenfeld <[email protected]> Reviewed-by: Eric Biggers <[email protected]> Signed-off-by: Herbert Xu <[email protected]>
sm00th · Mar 20, 2020 · c8cfcb7 · c8cfcb7
1 parent 1579f1b
commit c8cfcb7
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Showing 2 changed files with 12 additions and 7 deletions.
diff --git a/arch/arm64/crypto/chacha-neon-glue.c b/arch/arm64/crypto/chacha-neon-glue.c
@@ -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);
 	}
 }
 

diff --git a/lib/crypto/chacha20poly1305-selftest.c b/lib/crypto/chacha20poly1305-selftest.c
@@ -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);