1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
|
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ardb@kernel.org>
Date: Fri, 8 Nov 2019 13:22:40 +0100
Subject: [PATCH] crypto: lib/chacha20poly1305 - reimplement crypt_from_sg()
routine
commit d95312a3ccc0cd544d374be2fc45aeaa803e5fd9 upstream.
Reimplement the library routines to perform chacha20poly1305 en/decryption
on scatterlists, without [ab]using the [deprecated] blkcipher interface,
which is rather heavyweight and does things we don't really need.
Instead, we use the sg_miter API in a novel and clever way, to iterate
over the scatterlist in-place (i.e., source == destination, which is the
only way this library is expected to be used). That way, we don't have to
iterate over two scatterlists in parallel.
Another optimization is that, instead of relying on the blkcipher walker
to present the input in suitable chunks, we recognize that ChaCha is a
streamcipher, and so we can simply deal with partial blocks by keeping a
block of cipherstream on the stack and use crypto_xor() to mix it with
the in/output.
Finally, we omit the scatterwalk_and_copy() call if the last element of
the scatterlist covers the MAC as well (which is the common case),
avoiding the need to walk the scatterlist and kmap() the page twice.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
include/crypto/chacha20poly1305.h | 11 ++
lib/crypto/chacha20poly1305-selftest.c | 45 ++++++++
lib/crypto/chacha20poly1305.c | 150 +++++++++++++++++++++++++
3 files changed, 206 insertions(+)
--- a/include/crypto/chacha20poly1305.h
+++ b/include/crypto/chacha20poly1305.h
@@ -7,6 +7,7 @@
#define __CHACHA20POLY1305_H
#include <linux/types.h>
+#include <linux/scatterlist.h>
enum chacha20poly1305_lengths {
XCHACHA20POLY1305_NONCE_SIZE = 24,
@@ -34,4 +35,14 @@ bool __must_check xchacha20poly1305_decr
const size_t ad_len, const u8 nonce[XCHACHA20POLY1305_NONCE_SIZE],
const u8 key[CHACHA20POLY1305_KEY_SIZE]);
+bool chacha20poly1305_encrypt_sg_inplace(struct scatterlist *src, size_t src_len,
+ const u8 *ad, const size_t ad_len,
+ const u64 nonce,
+ const u8 key[CHACHA20POLY1305_KEY_SIZE]);
+
+bool chacha20poly1305_decrypt_sg_inplace(struct scatterlist *src, size_t src_len,
+ const u8 *ad, const size_t ad_len,
+ const u64 nonce,
+ const u8 key[CHACHA20POLY1305_KEY_SIZE]);
+
#endif /* __CHACHA20POLY1305_H */
--- a/lib/crypto/chacha20poly1305-selftest.c
+++ b/lib/crypto/chacha20poly1305-selftest.c
@@ -7250,6 +7250,7 @@ bool __init chacha20poly1305_selftest(vo
enum { MAXIMUM_TEST_BUFFER_LEN = 1UL << 12 };
size_t i;
u8 *computed_output = NULL, *heap_src = NULL;
+ struct scatterlist sg_src;
bool success = true, ret;
heap_src = kmalloc(MAXIMUM_TEST_BUFFER_LEN, GFP_KERNEL);
@@ -7280,6 +7281,29 @@ bool __init chacha20poly1305_selftest(vo
}
}
+ for (i = 0; i < ARRAY_SIZE(chacha20poly1305_enc_vectors); ++i) {
+ if (chacha20poly1305_enc_vectors[i].nlen != 8)
+ continue;
+ memcpy(heap_src, chacha20poly1305_enc_vectors[i].input,
+ chacha20poly1305_enc_vectors[i].ilen);
+ sg_init_one(&sg_src, heap_src,
+ chacha20poly1305_enc_vectors[i].ilen + POLY1305_DIGEST_SIZE);
+ chacha20poly1305_encrypt_sg_inplace(&sg_src,
+ chacha20poly1305_enc_vectors[i].ilen,
+ chacha20poly1305_enc_vectors[i].assoc,
+ chacha20poly1305_enc_vectors[i].alen,
+ get_unaligned_le64(chacha20poly1305_enc_vectors[i].nonce),
+ chacha20poly1305_enc_vectors[i].key);
+ if (memcmp(heap_src,
+ chacha20poly1305_enc_vectors[i].output,
+ chacha20poly1305_enc_vectors[i].ilen +
+ POLY1305_DIGEST_SIZE)) {
+ pr_err("chacha20poly1305 sg encryption self-test %zu: FAIL\n",
+ i + 1);
+ success = false;
+ }
+ }
+
for (i = 0; i < ARRAY_SIZE(chacha20poly1305_dec_vectors); ++i) {
memset(computed_output, 0, MAXIMUM_TEST_BUFFER_LEN);
ret = chacha20poly1305_decrypt(computed_output,
@@ -7301,6 +7325,27 @@ bool __init chacha20poly1305_selftest(vo
}
}
+ for (i = 0; i < ARRAY_SIZE(chacha20poly1305_dec_vectors); ++i) {
+ memcpy(heap_src, chacha20poly1305_dec_vectors[i].input,
+ chacha20poly1305_dec_vectors[i].ilen);
+ sg_init_one(&sg_src, heap_src,
+ chacha20poly1305_dec_vectors[i].ilen);
+ ret = chacha20poly1305_decrypt_sg_inplace(&sg_src,
+ chacha20poly1305_dec_vectors[i].ilen,
+ chacha20poly1305_dec_vectors[i].assoc,
+ chacha20poly1305_dec_vectors[i].alen,
+ get_unaligned_le64(chacha20poly1305_dec_vectors[i].nonce),
+ chacha20poly1305_dec_vectors[i].key);
+ if (!decryption_success(ret,
+ chacha20poly1305_dec_vectors[i].failure,
+ memcmp(heap_src, chacha20poly1305_dec_vectors[i].output,
+ chacha20poly1305_dec_vectors[i].ilen -
+ POLY1305_DIGEST_SIZE))) {
+ pr_err("chacha20poly1305 sg decryption self-test %zu: FAIL\n",
+ i + 1);
+ success = false;
+ }
+ }
for (i = 0; i < ARRAY_SIZE(xchacha20poly1305_enc_vectors); ++i) {
memset(computed_output, 0, MAXIMUM_TEST_BUFFER_LEN);
--- a/lib/crypto/chacha20poly1305.c
+++ b/lib/crypto/chacha20poly1305.c
@@ -11,6 +11,7 @@
#include <crypto/chacha20poly1305.h>
#include <crypto/chacha.h>
#include <crypto/poly1305.h>
+#include <crypto/scatterwalk.h>
#include <asm/unaligned.h>
#include <linux/kernel.h>
@@ -205,6 +206,155 @@ bool xchacha20poly1305_decrypt(u8 *dst,
}
EXPORT_SYMBOL(xchacha20poly1305_decrypt);
+static
+bool chacha20poly1305_crypt_sg_inplace(struct scatterlist *src,
+ const size_t src_len,
+ const u8 *ad, const size_t ad_len,
+ const u64 nonce,
+ const u8 key[CHACHA20POLY1305_KEY_SIZE],
+ int encrypt)
+{
+ const u8 *pad0 = page_address(ZERO_PAGE(0));
+ struct poly1305_desc_ctx poly1305_state;
+ u32 chacha_state[CHACHA_STATE_WORDS];
+ struct sg_mapping_iter miter;
+ size_t partial = 0;
+ unsigned int flags;
+ bool ret = true;
+ int sl;
+ union {
+ struct {
+ u32 k[CHACHA_KEY_WORDS];
+ __le64 iv[2];
+ };
+ u8 block0[POLY1305_KEY_SIZE];
+ u8 chacha_stream[CHACHA_BLOCK_SIZE];
+ struct {
+ u8 mac[2][POLY1305_DIGEST_SIZE];
+ };
+ __le64 lens[2];
+ } b __aligned(16);
+
+ chacha_load_key(b.k, key);
+
+ b.iv[0] = 0;
+ b.iv[1] = cpu_to_le64(nonce);
+
+ chacha_init(chacha_state, b.k, (u8 *)b.iv);
+ chacha_crypt(chacha_state, b.block0, pad0, sizeof(b.block0), 20);
+ poly1305_init(&poly1305_state, b.block0);
+
+ if (unlikely(ad_len)) {
+ poly1305_update(&poly1305_state, ad, ad_len);
+ if (ad_len & 0xf)
+ poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf));
+ }
+
+ flags = SG_MITER_TO_SG;
+ if (!preemptible())
+ flags |= SG_MITER_ATOMIC;
+
+ sg_miter_start(&miter, src, sg_nents(src), flags);
+
+ for (sl = src_len; sl > 0 && sg_miter_next(&miter); sl -= miter.length) {
+ u8 *addr = miter.addr;
+ size_t length = min_t(size_t, sl, miter.length);
+
+ if (!encrypt)
+ poly1305_update(&poly1305_state, addr, length);
+
+ if (unlikely(partial)) {
+ size_t l = min(length, CHACHA_BLOCK_SIZE - partial);
+
+ crypto_xor(addr, b.chacha_stream + partial, l);
+ partial = (partial + l) & (CHACHA_BLOCK_SIZE - 1);
+
+ addr += l;
+ length -= l;
+ }
+
+ if (likely(length >= CHACHA_BLOCK_SIZE || length == sl)) {
+ size_t l = length;
+
+ if (unlikely(length < sl))
+ l &= ~(CHACHA_BLOCK_SIZE - 1);
+ chacha_crypt(chacha_state, addr, addr, l, 20);
+ addr += l;
+ length -= l;
+ }
+
+ if (unlikely(length > 0)) {
+ chacha_crypt(chacha_state, b.chacha_stream, pad0,
+ CHACHA_BLOCK_SIZE, 20);
+ crypto_xor(addr, b.chacha_stream, length);
+ partial = length;
+ }
+
+ if (encrypt)
+ poly1305_update(&poly1305_state, miter.addr,
+ min_t(size_t, sl, miter.length));
+ }
+
+ if (src_len & 0xf)
+ poly1305_update(&poly1305_state, pad0, 0x10 - (src_len & 0xf));
+
+ b.lens[0] = cpu_to_le64(ad_len);
+ b.lens[1] = cpu_to_le64(src_len);
+ poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens));
+
+ if (likely(sl <= -POLY1305_DIGEST_SIZE)) {
+ if (encrypt) {
+ poly1305_final(&poly1305_state,
+ miter.addr + miter.length + sl);
+ ret = true;
+ } else {
+ poly1305_final(&poly1305_state, b.mac[0]);
+ ret = !crypto_memneq(b.mac[0],
+ miter.addr + miter.length + sl,
+ POLY1305_DIGEST_SIZE);
+ }
+ }
+
+ sg_miter_stop(&miter);
+
+ if (unlikely(sl > -POLY1305_DIGEST_SIZE)) {
+ poly1305_final(&poly1305_state, b.mac[1]);
+ scatterwalk_map_and_copy(b.mac[encrypt], src, src_len,
+ sizeof(b.mac[1]), encrypt);
+ ret = encrypt ||
+ !crypto_memneq(b.mac[0], b.mac[1], POLY1305_DIGEST_SIZE);
+ }
+
+ memzero_explicit(chacha_state, sizeof(chacha_state));
+ memzero_explicit(&b, sizeof(b));
+
+ return ret;
+}
+
+bool chacha20poly1305_encrypt_sg_inplace(struct scatterlist *src, size_t src_len,
+ const u8 *ad, const size_t ad_len,
+ const u64 nonce,
+ const u8 key[CHACHA20POLY1305_KEY_SIZE])
+{
+ return chacha20poly1305_crypt_sg_inplace(src, src_len, ad, ad_len,
+ nonce, key, 1);
+}
+EXPORT_SYMBOL(chacha20poly1305_encrypt_sg_inplace);
+
+bool chacha20poly1305_decrypt_sg_inplace(struct scatterlist *src, size_t src_len,
+ const u8 *ad, const size_t ad_len,
+ const u64 nonce,
+ const u8 key[CHACHA20POLY1305_KEY_SIZE])
+{
+ if (unlikely(src_len < POLY1305_DIGEST_SIZE))
+ return false;
+
+ return chacha20poly1305_crypt_sg_inplace(src,
+ src_len - POLY1305_DIGEST_SIZE,
+ ad, ad_len, nonce, key, 0);
+}
+EXPORT_SYMBOL(chacha20poly1305_decrypt_sg_inplace);
+
static int __init mod_init(void)
{
if (!IS_ENABLED(CONFIG_CRYPTO_MANAGER_DISABLE_TESTS) &&
|