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[mirror_ubuntu-bionic-kernel.git] / net / ceph / crypto.c
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 */
23 static 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_skcipher() allocates with GFP_KERNEL */
50 noio_flag = memalloc_noio_save();
51 key->tfm = crypto_alloc_skcipher("cbc(aes)", 0, CRYPTO_ALG_ASYNC);
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_skcipher_setkey(key->tfm, key->key, key->len);
60 if (ret)
61 goto fail;
62
63 return 0;
64
65 fail:
66 ceph_crypto_key_destroy(key);
67 return ret;
68 }
69
70 int 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
77 int 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
89 int 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 *p += key->len;
100 return ret;
101
102 bad:
103 dout("failed to decode crypto key\n");
104 return -EINVAL;
105 }
106
107 int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *inkey)
108 {
109 int inlen = strlen(inkey);
110 int blen = inlen * 3 / 4;
111 void *buf, *p;
112 int ret;
113
114 dout("crypto_key_unarmor %s\n", inkey);
115 buf = kmalloc(blen, GFP_NOFS);
116 if (!buf)
117 return -ENOMEM;
118 blen = ceph_unarmor(buf, inkey, inkey+inlen);
119 if (blen < 0) {
120 kfree(buf);
121 return blen;
122 }
123
124 p = buf;
125 ret = ceph_crypto_key_decode(key, &p, p + blen);
126 kfree(buf);
127 if (ret)
128 return ret;
129 dout("crypto_key_unarmor key %p type %d len %d\n", key,
130 key->type, key->len);
131 return 0;
132 }
133
134 void ceph_crypto_key_destroy(struct ceph_crypto_key *key)
135 {
136 if (key) {
137 kfree(key->key);
138 key->key = NULL;
139 crypto_free_skcipher(key->tfm);
140 key->tfm = NULL;
141 }
142 }
143
144 static const u8 *aes_iv = (u8 *)CEPH_AES_IV;
145
146 /*
147 * Should be used for buffers allocated with ceph_kvmalloc().
148 * Currently these are encrypt out-buffer (ceph_buffer) and decrypt
149 * in-buffer (msg front).
150 *
151 * Dispose of @sgt with teardown_sgtable().
152 *
153 * @prealloc_sg is to avoid memory allocation inside sg_alloc_table()
154 * in cases where a single sg is sufficient. No attempt to reduce the
155 * number of sgs by squeezing physically contiguous pages together is
156 * made though, for simplicity.
157 */
158 static int setup_sgtable(struct sg_table *sgt, struct scatterlist *prealloc_sg,
159 const void *buf, unsigned int buf_len)
160 {
161 struct scatterlist *sg;
162 const bool is_vmalloc = is_vmalloc_addr(buf);
163 unsigned int off = offset_in_page(buf);
164 unsigned int chunk_cnt = 1;
165 unsigned int chunk_len = PAGE_ALIGN(off + buf_len);
166 int i;
167 int ret;
168
169 if (buf_len == 0) {
170 memset(sgt, 0, sizeof(*sgt));
171 return -EINVAL;
172 }
173
174 if (is_vmalloc) {
175 chunk_cnt = chunk_len >> PAGE_SHIFT;
176 chunk_len = PAGE_SIZE;
177 }
178
179 if (chunk_cnt > 1) {
180 ret = sg_alloc_table(sgt, chunk_cnt, GFP_NOFS);
181 if (ret)
182 return ret;
183 } else {
184 WARN_ON(chunk_cnt != 1);
185 sg_init_table(prealloc_sg, 1);
186 sgt->sgl = prealloc_sg;
187 sgt->nents = sgt->orig_nents = 1;
188 }
189
190 for_each_sg(sgt->sgl, sg, sgt->orig_nents, i) {
191 struct page *page;
192 unsigned int len = min(chunk_len - off, buf_len);
193
194 if (is_vmalloc)
195 page = vmalloc_to_page(buf);
196 else
197 page = virt_to_page(buf);
198
199 sg_set_page(sg, page, len, off);
200
201 off = 0;
202 buf += len;
203 buf_len -= len;
204 }
205 WARN_ON(buf_len != 0);
206
207 return 0;
208 }
209
210 static void teardown_sgtable(struct sg_table *sgt)
211 {
212 if (sgt->orig_nents > 1)
213 sg_free_table(sgt);
214 }
215
216 static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
217 void *buf, int buf_len, int in_len, int *pout_len)
218 {
219 SKCIPHER_REQUEST_ON_STACK(req, key->tfm);
220 struct sg_table sgt;
221 struct scatterlist prealloc_sg;
222 char iv[AES_BLOCK_SIZE] __aligned(8);
223 int pad_byte = AES_BLOCK_SIZE - (in_len & (AES_BLOCK_SIZE - 1));
224 int crypt_len = encrypt ? in_len + pad_byte : in_len;
225 int ret;
226
227 WARN_ON(crypt_len > buf_len);
228 if (encrypt)
229 memset(buf + in_len, pad_byte, pad_byte);
230 ret = setup_sgtable(&sgt, &prealloc_sg, buf, crypt_len);
231 if (ret)
232 return ret;
233
234 memcpy(iv, aes_iv, AES_BLOCK_SIZE);
235 skcipher_request_set_tfm(req, key->tfm);
236 skcipher_request_set_callback(req, 0, NULL, NULL);
237 skcipher_request_set_crypt(req, sgt.sgl, sgt.sgl, crypt_len, iv);
238
239 /*
240 print_hex_dump(KERN_ERR, "key: ", DUMP_PREFIX_NONE, 16, 1,
241 key->key, key->len, 1);
242 print_hex_dump(KERN_ERR, " in: ", DUMP_PREFIX_NONE, 16, 1,
243 buf, crypt_len, 1);
244 */
245 if (encrypt)
246 ret = crypto_skcipher_encrypt(req);
247 else
248 ret = crypto_skcipher_decrypt(req);
249 skcipher_request_zero(req);
250 if (ret) {
251 pr_err("%s %scrypt failed: %d\n", __func__,
252 encrypt ? "en" : "de", ret);
253 goto out_sgt;
254 }
255 /*
256 print_hex_dump(KERN_ERR, "out: ", DUMP_PREFIX_NONE, 16, 1,
257 buf, crypt_len, 1);
258 */
259
260 if (encrypt) {
261 *pout_len = crypt_len;
262 } else {
263 pad_byte = *(char *)(buf + in_len - 1);
264 if (pad_byte > 0 && pad_byte <= AES_BLOCK_SIZE &&
265 in_len >= pad_byte) {
266 *pout_len = in_len - pad_byte;
267 } else {
268 pr_err("%s got bad padding %d on in_len %d\n",
269 __func__, pad_byte, in_len);
270 ret = -EPERM;
271 goto out_sgt;
272 }
273 }
274
275 out_sgt:
276 teardown_sgtable(&sgt);
277 return ret;
278 }
279
280 int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
281 void *buf, int buf_len, int in_len, int *pout_len)
282 {
283 switch (key->type) {
284 case CEPH_CRYPTO_NONE:
285 *pout_len = in_len;
286 return 0;
287 case CEPH_CRYPTO_AES:
288 return ceph_aes_crypt(key, encrypt, buf, buf_len, in_len,
289 pout_len);
290 default:
291 return -ENOTSUPP;
292 }
293 }
294
295 static int ceph_key_preparse(struct key_preparsed_payload *prep)
296 {
297 struct ceph_crypto_key *ckey;
298 size_t datalen = prep->datalen;
299 int ret;
300 void *p;
301
302 ret = -EINVAL;
303 if (datalen <= 0 || datalen > 32767 || !prep->data)
304 goto err;
305
306 ret = -ENOMEM;
307 ckey = kmalloc(sizeof(*ckey), GFP_KERNEL);
308 if (!ckey)
309 goto err;
310
311 /* TODO ceph_crypto_key_decode should really take const input */
312 p = (void *)prep->data;
313 ret = ceph_crypto_key_decode(ckey, &p, (char*)prep->data+datalen);
314 if (ret < 0)
315 goto err_ckey;
316
317 prep->payload.data[0] = ckey;
318 prep->quotalen = datalen;
319 return 0;
320
321 err_ckey:
322 kfree(ckey);
323 err:
324 return ret;
325 }
326
327 static void ceph_key_free_preparse(struct key_preparsed_payload *prep)
328 {
329 struct ceph_crypto_key *ckey = prep->payload.data[0];
330 ceph_crypto_key_destroy(ckey);
331 kfree(ckey);
332 }
333
334 static void ceph_key_destroy(struct key *key)
335 {
336 struct ceph_crypto_key *ckey = key->payload.data[0];
337
338 ceph_crypto_key_destroy(ckey);
339 kfree(ckey);
340 }
341
342 struct key_type key_type_ceph = {
343 .name = "ceph",
344 .preparse = ceph_key_preparse,
345 .free_preparse = ceph_key_free_preparse,
346 .instantiate = generic_key_instantiate,
347 .destroy = ceph_key_destroy,
348 };
349
350 int ceph_crypto_init(void) {
351 return register_key_type(&key_type_ceph);
352 }
353
354 void ceph_crypto_shutdown(void) {
355 unregister_key_type(&key_type_ceph);
356 }