summaryrefslogtreecommitdiffstats
path: root/net/ceph/crypto.c
blob: 3949ce70be07bc90b1ee7e67ca95f09c1d5258f3 (plain)
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
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
#include <linux/ceph/ceph_debug.h>

#include <linux/err.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <crypto/aes.h>
#include <crypto/skcipher.h>
#include <linux/key-type.h>

#include <keys/ceph-type.h>
#include <keys/user-type.h>
#include <linux/ceph/decode.h>
#include "crypto.h"

/*
 * Set ->key and ->tfm.  The rest of the key should be filled in before
 * this function is called.
 */
static int set_secret(struct ceph_crypto_key *key, void *buf)
{
	unsigned int noio_flag;
	int ret;

	key->key = NULL;
	key->tfm = NULL;

	switch (key->type) {
	case CEPH_CRYPTO_NONE:
		return 0; /* nothing to do */
	case CEPH_CRYPTO_AES:
		break;
	default:
		return -ENOTSUPP;
	}

	WARN_ON(!key->len);
	key->key = kmemdup(buf, key->len, GFP_NOIO);
	if (!key->key) {
		ret = -ENOMEM;
		goto fail;
	}

	/* crypto_alloc_skcipher() allocates with GFP_KERNEL */
	noio_flag = memalloc_noio_save();
	key->tfm = crypto_alloc_skcipher("cbc(aes)", 0, CRYPTO_ALG_ASYNC);
	memalloc_noio_restore(noio_flag);
	if (IS_ERR(key->tfm)) {
		ret = PTR_ERR(key->tfm);
		key->tfm = NULL;
		goto fail;
	}

	ret = crypto_skcipher_setkey(key->tfm, key->key, key->len);
	if (ret)
		goto fail;

	return 0;

fail:
	ceph_crypto_key_destroy(key);
	return ret;
}

int ceph_crypto_key_clone(struct ceph_crypto_key *dst,
			  const struct ceph_crypto_key *src)
{
	memcpy(dst, src, sizeof(struct ceph_crypto_key));
	return set_secret(dst, src->key);
}

int ceph_crypto_key_encode(struct ceph_crypto_key *key, void **p, void *end)
{
	if (*p + sizeof(u16) + sizeof(key->created) +
	    sizeof(u16) + key->len > end)
		return -ERANGE;
	ceph_encode_16(p, key->type);
	ceph_encode_copy(p, &key->created, sizeof(key->created));
	ceph_encode_16(p, key->len);
	ceph_encode_copy(p, key->key, key->len);
	return 0;
}

int ceph_crypto_key_decode(struct ceph_crypto_key *key, void **p, void *end)
{
	int ret;

	ceph_decode_need(p, end, 2*sizeof(u16) + sizeof(key->created), bad);
	key->type = ceph_decode_16(p);
	ceph_decode_copy(p, &key->created, sizeof(key->created));
	key->len = ceph_decode_16(p);
	ceph_decode_need(p, end, key->len, bad);
	ret = set_secret(key, *p);
	*p += key->len;
	return ret;

bad:
	dout("failed to decode crypto key\n");
	return -EINVAL;
}

int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *inkey)
{
	int inlen = strlen(inkey);
	int blen = inlen * 3 / 4;
	void *buf, *p;
	int ret;

	dout("crypto_key_unarmor %s\n", inkey);
	buf = kmalloc(blen, GFP_NOFS);
	if (!buf)
		return -ENOMEM;
	blen = ceph_unarmor(buf, inkey, inkey+inlen);
	if (blen < 0) {
		kfree(buf);
		return blen;
	}

	p = buf;
	ret = ceph_crypto_key_decode(key, &p, p + blen);
	kfree(buf);
	if (ret)
		return ret;
	dout("crypto_key_unarmor key %p type %d len %d\n", key,
	     key->type, key->len);
	return 0;
}

void ceph_crypto_key_destroy(struct ceph_crypto_key *key)
{
	if (key) {
		kfree(key->key);
		key->key = NULL;
		crypto_free_skcipher(key->tfm);
		key->tfm = NULL;
	}
}

static const u8 *aes_iv = (u8 *)CEPH_AES_IV;

/*
 * Should be used for buffers allocated with ceph_kvmalloc().
 * Currently these are encrypt out-buffer (ceph_buffer) and decrypt
 * in-buffer (msg front).
 *
 * Dispose of @sgt with teardown_sgtable().
 *
 * @prealloc_sg is to avoid memory allocation inside sg_alloc_table()
 * in cases where a single sg is sufficient.  No attempt to reduce the
 * number of sgs by squeezing physically contiguous pages together is
 * made though, for simplicity.
 */
static int setup_sgtable(struct sg_table *sgt, struct scatterlist *prealloc_sg,
			 const void *buf, unsigned int buf_len)
{
	struct scatterlist *sg;
	const bool is_vmalloc = is_vmalloc_addr(buf);
	unsigned int off = offset_in_page(buf);
	unsigned int chunk_cnt = 1;
	unsigned int chunk_len = PAGE_ALIGN(off + buf_len);
	int i;
	int ret;

	if (buf_len == 0) {
		memset(sgt, 0, sizeof(*sgt));
		return -EINVAL;
	}

	if (is_vmalloc) {
		chunk_cnt = chunk_len >> PAGE_SHIFT;
		chunk_len = PAGE_SIZE;
	}

	if (chunk_cnt > 1) {
		ret = sg_alloc_table(sgt, chunk_cnt, GFP_NOFS);
		if (ret)
			return ret;
	} else {
		WARN_ON(chunk_cnt != 1);
		sg_init_table(prealloc_sg, 1);
		sgt->sgl = prealloc_sg;
		sgt->nents = sgt->orig_nents = 1;
	}

	for_each_sg(sgt->sgl, sg, sgt->orig_nents, i) {
		struct page *page;
		unsigned int len = min(chunk_len - off, buf_len);

		if (is_vmalloc)
			page = vmalloc_to_page(buf);
		else
			page = virt_to_page(buf);

		sg_set_page(sg, page, len, off);

		off = 0;
		buf += len;
		buf_len -= len;
	}
	WARN_ON(buf_len != 0);

	return 0;
}

static void teardown_sgtable(struct sg_table *sgt)
{
	if (sgt->orig_nents > 1)
		sg_free_table(sgt);
}

static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
			  void *buf, int buf_len, int in_len, int *pout_len)
{
	SKCIPHER_REQUEST_ON_STACK(req, key->tfm);
	struct sg_table sgt;
	struct scatterlist prealloc_sg;
	char iv[AES_BLOCK_SIZE];
	int pad_byte = AES_BLOCK_SIZE - (in_len & (AES_BLOCK_SIZE - 1));
	int crypt_len = encrypt ? in_len + pad_byte : in_len;
	int ret;

	WARN_ON(crypt_len > buf_len);
	if (encrypt)
		memset(buf + in_len, pad_byte, pad_byte);
	ret = setup_sgtable(&sgt, &prealloc_sg, buf, crypt_len);
	if (ret)
		return ret;

	memcpy(iv, aes_iv, AES_BLOCK_SIZE);
	skcipher_request_set_tfm(req, key->tfm);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sgt.sgl, sgt.sgl, crypt_len, iv);

	/*
	print_hex_dump(KERN_ERR, "key: ", DUMP_PREFIX_NONE, 16, 1,
		       key->key, key->len, 1);
	print_hex_dump(KERN_ERR, " in: ", DUMP_PREFIX_NONE, 16, 1,
		       buf, crypt_len, 1);
	*/
	if (encrypt)
		ret = crypto_skcipher_encrypt(req);
	else
		ret = crypto_skcipher_decrypt(req);
	skcipher_request_zero(req);
	if (ret) {
		pr_err("%s %scrypt failed: %d\n", __func__,
		       encrypt ? "en" : "de", ret);
		goto out_sgt;
	}
	/*
	print_hex_dump(KERN_ERR, "out: ", DUMP_PREFIX_NONE, 16, 1,
		       buf, crypt_len, 1);
	*/

	if (encrypt) {
		*pout_len = crypt_len;
	} else {
		pad_byte = *(char *)(buf + in_len - 1);
		if (pad_byte > 0 && pad_byte <= AES_BLOCK_SIZE &&
		    in_len >= pad_byte) {
			*pout_len = in_len - pad_byte;
		} else {
			pr_err("%s got bad padding %d on in_len %d\n",
			       __func__, pad_byte, in_len);
			ret = -EPERM;
			goto out_sgt;
		}
	}

out_sgt:
	teardown_sgtable(&sgt);
	return ret;
}

int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
	       void *buf, int buf_len, int in_len, int *pout_len)
{
	switch (key->type) {
	case CEPH_CRYPTO_NONE:
		*pout_len = in_len;
		return 0;
	case CEPH_CRYPTO_AES:
		return ceph_aes_crypt(key, encrypt, buf, buf_len, in_len,
				      pout_len);
	default:
		return -ENOTSUPP;
	}
}

static int ceph_key_preparse(struct key_preparsed_payload *prep)
{
	struct ceph_crypto_key *ckey;
	size_t datalen = prep->datalen;
	int ret;
	void *p;

	ret = -EINVAL;
	if (datalen <= 0 || datalen > 32767 || !prep->data)
		goto err;

	ret = -ENOMEM;
	ckey = kmalloc(sizeof(*ckey), GFP_KERNEL);
	if (!ckey)
		goto err;

	/* TODO ceph_crypto_key_decode should really take const input */
	p = (void *)prep->data;
	ret = ceph_crypto_key_decode(ckey, &p, (char*)prep->data+datalen);
	if (ret < 0)
		goto err_ckey;

	prep->payload.data[0] = ckey;
	prep->quotalen = datalen;
	return 0;

err_ckey:
	kfree(ckey);
err:
	return ret;
}

static void ceph_key_free_preparse(struct key_preparsed_payload *prep)
{
	struct ceph_crypto_key *ckey = prep->payload.data[0];
	ceph_crypto_key_destroy(ckey);
	kfree(ckey);
}

static void ceph_key_destroy(struct key *key)
{
	struct ceph_crypto_key *ckey = key->payload.data[0];

	ceph_crypto_key_destroy(ckey);
	kfree(ckey);
}

struct key_type key_type_ceph = {
	.name		= "ceph",
	.preparse	= ceph_key_preparse,
	.free_preparse	= ceph_key_free_preparse,
	.instantiate	= generic_key_instantiate,
	.destroy	= ceph_key_destroy,
};

int ceph_crypto_init(void) {
	return register_key_type(&key_type_ceph);
}

void ceph_crypto_shutdown(void) {
	unregister_key_type(&key_type_ceph);
}