1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/ceph/ceph_debug.h>
4
5#include <linux/err.h>
6#include <linux/scatterlist.h>
7#include <linux/sched.h>
8#include <linux/slab.h>
9#include <crypto/aes.h>
10#include <crypto/skcipher.h>
11#include <linux/key-type.h>
12#include <linux/sched/mm.h>
13
14#include <keys/ceph-type.h>
15#include <keys/user-type.h>
16#include <linux/ceph/decode.h>
17#include "crypto.h"
18
19/*
20 * Set ->key and ->tfm.  The rest of the key should be filled in before
21 * this function is called.
22 */
23static int set_secret(struct ceph_crypto_key *key, void *buf)
24{
25	unsigned int noio_flag;
26	int ret;
27
28	key->key = NULL;
29	key->tfm = NULL;
30
31	switch (key->type) {
32	case CEPH_CRYPTO_NONE:
33		return 0; /* nothing to do */
34	case CEPH_CRYPTO_AES:
35		break;
36	default:
37		return -ENOTSUPP;
38	}
39
40	if (!key->len)
41		return -EINVAL;
42
43	key->key = kmemdup(buf, key->len, GFP_NOIO);
44	if (!key->key) {
45		ret = -ENOMEM;
46		goto fail;
47	}
48
49	/* crypto_alloc_sync_skcipher() allocates with GFP_KERNEL */
50	noio_flag = memalloc_noio_save();
51	key->tfm = crypto_alloc_sync_skcipher("cbc(aes)", 0, 0);
52	memalloc_noio_restore(noio_flag);
53	if (IS_ERR(key->tfm)) {
54		ret = PTR_ERR(key->tfm);
55		key->tfm = NULL;
56		goto fail;
57	}
58
59	ret = crypto_sync_skcipher_setkey(key->tfm, key->key, key->len);
60	if (ret)
61		goto fail;
62
63	return 0;
64
65fail:
66	ceph_crypto_key_destroy(key);
67	return ret;
68}
69
70int ceph_crypto_key_clone(struct ceph_crypto_key *dst,
71			  const struct ceph_crypto_key *src)
72{
73	memcpy(dst, src, sizeof(struct ceph_crypto_key));
74	return set_secret(dst, src->key);
75}
76
77int ceph_crypto_key_encode(struct ceph_crypto_key *key, void **p, void *end)
78{
79	if (*p + sizeof(u16) + sizeof(key->created) +
80	    sizeof(u16) + key->len > end)
81		return -ERANGE;
82	ceph_encode_16(p, key->type);
83	ceph_encode_copy(p, &key->created, sizeof(key->created));
84	ceph_encode_16(p, key->len);
85	ceph_encode_copy(p, key->key, key->len);
86	return 0;
87}
88
89int ceph_crypto_key_decode(struct ceph_crypto_key *key, void **p, void *end)
90{
91	int ret;
92
93	ceph_decode_need(p, end, 2*sizeof(u16) + sizeof(key->created), bad);
94	key->type = ceph_decode_16(p);
95	ceph_decode_copy(p, &key->created, sizeof(key->created));
96	key->len = ceph_decode_16(p);
97	ceph_decode_need(p, end, key->len, bad);
98	ret = set_secret(key, *p);
99	memzero_explicit(*p, key->len);
100	*p += key->len;
101	return ret;
102
103bad:
104	dout("failed to decode crypto key\n");
105	return -EINVAL;
106}
107
108int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *inkey)
109{
110	int inlen = strlen(inkey);
111	int blen = inlen * 3 / 4;
112	void *buf, *p;
113	int ret;
114
115	dout("crypto_key_unarmor %s\n", inkey);
116	buf = kmalloc(blen, GFP_NOFS);
117	if (!buf)
118		return -ENOMEM;
119	blen = ceph_unarmor(buf, inkey, inkey+inlen);
120	if (blen < 0) {
121		kfree(buf);
122		return blen;
123	}
124
125	p = buf;
126	ret = ceph_crypto_key_decode(key, &p, p + blen);
127	kfree(buf);
128	if (ret)
129		return ret;
130	dout("crypto_key_unarmor key %p type %d len %d\n", key,
131	     key->type, key->len);
132	return 0;
133}
134
135void ceph_crypto_key_destroy(struct ceph_crypto_key *key)
136{
137	if (key) {
138		kfree_sensitive(key->key);
139		key->key = NULL;
140		if (key->tfm) {
141			crypto_free_sync_skcipher(key->tfm);
142			key->tfm = NULL;
143		}
144	}
145}
146
147static const u8 *aes_iv = (u8 *)CEPH_AES_IV;
148
149/*
150 * Should be used for buffers allocated with kvmalloc().
151 * Currently these are encrypt out-buffer (ceph_buffer) and decrypt
152 * in-buffer (msg front).
153 *
154 * Dispose of @sgt with teardown_sgtable().
155 *
156 * @prealloc_sg is to avoid memory allocation inside sg_alloc_table()
157 * in cases where a single sg is sufficient.  No attempt to reduce the
158 * number of sgs by squeezing physically contiguous pages together is
159 * made though, for simplicity.
160 */
161static int setup_sgtable(struct sg_table *sgt, struct scatterlist *prealloc_sg,
162			 const void *buf, unsigned int buf_len)
163{
164	struct scatterlist *sg;
165	const bool is_vmalloc = is_vmalloc_addr(buf);
166	unsigned int off = offset_in_page(buf);
167	unsigned int chunk_cnt = 1;
168	unsigned int chunk_len = PAGE_ALIGN(off + buf_len);
169	int i;
170	int ret;
171
172	if (buf_len == 0) {
173		memset(sgt, 0, sizeof(*sgt));
174		return -EINVAL;
175	}
176
177	if (is_vmalloc) {
178		chunk_cnt = chunk_len >> PAGE_SHIFT;
179		chunk_len = PAGE_SIZE;
180	}
181
182	if (chunk_cnt > 1) {
183		ret = sg_alloc_table(sgt, chunk_cnt, GFP_NOFS);
184		if (ret)
185			return ret;
186	} else {
187		WARN_ON(chunk_cnt != 1);
188		sg_init_table(prealloc_sg, 1);
189		sgt->sgl = prealloc_sg;
190		sgt->nents = sgt->orig_nents = 1;
191	}
192
193	for_each_sg(sgt->sgl, sg, sgt->orig_nents, i) {
194		struct page *page;
195		unsigned int len = min(chunk_len - off, buf_len);
196
197		if (is_vmalloc)
198			page = vmalloc_to_page(buf);
199		else
200			page = virt_to_page(buf);
201
202		sg_set_page(sg, page, len, off);
203
204		off = 0;
205		buf += len;
206		buf_len -= len;
207	}
208	WARN_ON(buf_len != 0);
209
210	return 0;
211}
212
213static void teardown_sgtable(struct sg_table *sgt)
214{
215	if (sgt->orig_nents > 1)
216		sg_free_table(sgt);
217}
218
219static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
220			  void *buf, int buf_len, int in_len, int *pout_len)
221{
222	SYNC_SKCIPHER_REQUEST_ON_STACK(req, key->tfm);
223	struct sg_table sgt;
224	struct scatterlist prealloc_sg;
225	char iv[AES_BLOCK_SIZE] __aligned(8);
226	int pad_byte = AES_BLOCK_SIZE - (in_len & (AES_BLOCK_SIZE - 1));
227	int crypt_len = encrypt ? in_len + pad_byte : in_len;
228	int ret;
229
230	WARN_ON(crypt_len > buf_len);
231	if (encrypt)
232		memset(buf + in_len, pad_byte, pad_byte);
233	ret = setup_sgtable(&sgt, &prealloc_sg, buf, crypt_len);
234	if (ret)
235		return ret;
236
237	memcpy(iv, aes_iv, AES_BLOCK_SIZE);
238	skcipher_request_set_sync_tfm(req, key->tfm);
239	skcipher_request_set_callback(req, 0, NULL, NULL);
240	skcipher_request_set_crypt(req, sgt.sgl, sgt.sgl, crypt_len, iv);
241
242	/*
243	print_hex_dump(KERN_ERR, "key: ", DUMP_PREFIX_NONE, 16, 1,
244		       key->key, key->len, 1);
245	print_hex_dump(KERN_ERR, " in: ", DUMP_PREFIX_NONE, 16, 1,
246		       buf, crypt_len, 1);
247	*/
248	if (encrypt)
249		ret = crypto_skcipher_encrypt(req);
250	else
251		ret = crypto_skcipher_decrypt(req);
252	skcipher_request_zero(req);
253	if (ret) {
254		pr_err("%s %scrypt failed: %d\n", __func__,
255		       encrypt ? "en" : "de", ret);
256		goto out_sgt;
257	}
258	/*
259	print_hex_dump(KERN_ERR, "out: ", DUMP_PREFIX_NONE, 16, 1,
260		       buf, crypt_len, 1);
261	*/
262
263	if (encrypt) {
264		*pout_len = crypt_len;
265	} else {
266		pad_byte = *(char *)(buf + in_len - 1);
267		if (pad_byte > 0 && pad_byte <= AES_BLOCK_SIZE &&
268		    in_len >= pad_byte) {
269			*pout_len = in_len - pad_byte;
270		} else {
271			pr_err("%s got bad padding %d on in_len %d\n",
272			       __func__, pad_byte, in_len);
273			ret = -EPERM;
274			goto out_sgt;
275		}
276	}
277
278out_sgt:
279	teardown_sgtable(&sgt);
280	return ret;
281}
282
283int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
284	       void *buf, int buf_len, int in_len, int *pout_len)
285{
286	switch (key->type) {
287	case CEPH_CRYPTO_NONE:
288		*pout_len = in_len;
289		return 0;
290	case CEPH_CRYPTO_AES:
291		return ceph_aes_crypt(key, encrypt, buf, buf_len, in_len,
292				      pout_len);
293	default:
294		return -ENOTSUPP;
295	}
296}
297
298static int ceph_key_preparse(struct key_preparsed_payload *prep)
299{
300	struct ceph_crypto_key *ckey;
301	size_t datalen = prep->datalen;
302	int ret;
303	void *p;
304
305	ret = -EINVAL;
306	if (datalen <= 0 || datalen > 32767 || !prep->data)
307		goto err;
308
309	ret = -ENOMEM;
310	ckey = kmalloc(sizeof(*ckey), GFP_KERNEL);
311	if (!ckey)
312		goto err;
313
314	/* TODO ceph_crypto_key_decode should really take const input */
315	p = (void *)prep->data;
316	ret = ceph_crypto_key_decode(ckey, &p, (char*)prep->data+datalen);
317	if (ret < 0)
318		goto err_ckey;
319
320	prep->payload.data[0] = ckey;
321	prep->quotalen = datalen;
322	return 0;
323
324err_ckey:
325	kfree(ckey);
326err:
327	return ret;
328}
329
330static void ceph_key_free_preparse(struct key_preparsed_payload *prep)
331{
332	struct ceph_crypto_key *ckey = prep->payload.data[0];
333	ceph_crypto_key_destroy(ckey);
334	kfree(ckey);
335}
336
337static void ceph_key_destroy(struct key *key)
338{
339	struct ceph_crypto_key *ckey = key->payload.data[0];
340
341	ceph_crypto_key_destroy(ckey);
342	kfree(ckey);
343}
344
345struct key_type key_type_ceph = {
346	.name		= "ceph",
347	.preparse	= ceph_key_preparse,
348	.free_preparse	= ceph_key_free_preparse,
349	.instantiate	= generic_key_instantiate,
350	.destroy	= ceph_key_destroy,
351};
352
353int __init ceph_crypto_init(void)
354{
355	return register_key_type(&key_type_ceph);
356}
357
358void ceph_crypto_shutdown(void)
359{
360	unregister_key_type(&key_type_ceph);
361}
362