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_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
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 memzero_explicit(*p, key->len);
100 *p += key->len;
101 return ret;
102
103 bad:
104 dout("failed to decode crypto key\n");
105 return -EINVAL;
106 }
107
108 int 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
135 void 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
147 static 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 */
161 static 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
213 static void teardown_sgtable(struct sg_table *sgt)
214 {
215 if (sgt->orig_nents > 1)
216 sg_free_table(sgt);
217 }
218
219 static 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
278 out_sgt:
279 teardown_sgtable(&sgt);
280 return ret;
281 }
282
283 int 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
298 static 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
324 err_ckey:
325 kfree(ckey);
326 err:
327 return ret;
328 }
329
330 static 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
337 static 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
345 struct 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
353 int __init ceph_crypto_init(void)
354 {
355 return register_key_type(&key_type_ceph);
356 }
357
358 void ceph_crypto_shutdown(void)
359 {
360 unregister_key_type(&key_type_ceph);
361 }
362
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