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(alg_name: "cbc(aes)", type: 0, mask: 0);
52 memalloc_noio_restore(flags: noio_flag);
53 if (IS_ERR(ptr: key->tfm)) {
54 ret = PTR_ERR(ptr: key->tfm);
55 key->tfm = NULL;
56 goto fail;
57 }
58
59 ret = crypto_sync_skcipher_setkey(tfm: key->tfm, key: key->key, keylen: 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(key: dst, buf: src->key);
75}
76
77int ceph_crypto_key_decode(struct ceph_crypto_key *key, void **p, void *end)
78{
79 int ret;
80
81 ceph_decode_need(p, end, 2*sizeof(u16) + sizeof(key->created), bad);
82 key->type = ceph_decode_16(p);
83 ceph_decode_copy(p, pv: &key->created, n: sizeof(key->created));
84 key->len = ceph_decode_16(p);
85 ceph_decode_need(p, end, key->len, bad);
86 ret = set_secret(key, buf: *p);
87 memzero_explicit(s: *p, count: key->len);
88 *p += key->len;
89 return ret;
90
91bad:
92 dout("failed to decode crypto key\n");
93 return -EINVAL;
94}
95
96int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *inkey)
97{
98 int inlen = strlen(inkey);
99 int blen = inlen * 3 / 4;
100 void *buf, *p;
101 int ret;
102
103 dout("crypto_key_unarmor %s\n", inkey);
104 buf = kmalloc(blen, GFP_NOFS);
105 if (!buf)
106 return -ENOMEM;
107 blen = ceph_unarmor(dst: buf, src: inkey, end: inkey+inlen);
108 if (blen < 0) {
109 kfree(objp: buf);
110 return blen;
111 }
112
113 p = buf;
114 ret = ceph_crypto_key_decode(key, p: &p, end: p + blen);
115 kfree(objp: buf);
116 if (ret)
117 return ret;
118 dout("crypto_key_unarmor key %p type %d len %d\n", key,
119 key->type, key->len);
120 return 0;
121}
122
123void ceph_crypto_key_destroy(struct ceph_crypto_key *key)
124{
125 if (key) {
126 kfree_sensitive(objp: key->key);
127 key->key = NULL;
128 if (key->tfm) {
129 crypto_free_sync_skcipher(tfm: key->tfm);
130 key->tfm = NULL;
131 }
132 }
133}
134
135static const u8 *aes_iv = (u8 *)CEPH_AES_IV;
136
137/*
138 * Should be used for buffers allocated with kvmalloc().
139 * Currently these are encrypt out-buffer (ceph_buffer) and decrypt
140 * in-buffer (msg front).
141 *
142 * Dispose of @sgt with teardown_sgtable().
143 *
144 * @prealloc_sg is to avoid memory allocation inside sg_alloc_table()
145 * in cases where a single sg is sufficient. No attempt to reduce the
146 * number of sgs by squeezing physically contiguous pages together is
147 * made though, for simplicity.
148 */
149static int setup_sgtable(struct sg_table *sgt, struct scatterlist *prealloc_sg,
150 const void *buf, unsigned int buf_len)
151{
152 struct scatterlist *sg;
153 const bool is_vmalloc = is_vmalloc_addr(x: buf);
154 unsigned int off = offset_in_page(buf);
155 unsigned int chunk_cnt = 1;
156 unsigned int chunk_len = PAGE_ALIGN(off + buf_len);
157 int i;
158 int ret;
159
160 if (buf_len == 0) {
161 memset(sgt, 0, sizeof(*sgt));
162 return -EINVAL;
163 }
164
165 if (is_vmalloc) {
166 chunk_cnt = chunk_len >> PAGE_SHIFT;
167 chunk_len = PAGE_SIZE;
168 }
169
170 if (chunk_cnt > 1) {
171 ret = sg_alloc_table(sgt, chunk_cnt, GFP_NOFS);
172 if (ret)
173 return ret;
174 } else {
175 WARN_ON(chunk_cnt != 1);
176 sg_init_table(prealloc_sg, 1);
177 sgt->sgl = prealloc_sg;
178 sgt->nents = sgt->orig_nents = 1;
179 }
180
181 for_each_sg(sgt->sgl, sg, sgt->orig_nents, i) {
182 struct page *page;
183 unsigned int len = min(chunk_len - off, buf_len);
184
185 if (is_vmalloc)
186 page = vmalloc_to_page(addr: buf);
187 else
188 page = virt_to_page(buf);
189
190 sg_set_page(sg, page, len, offset: off);
191
192 off = 0;
193 buf += len;
194 buf_len -= len;
195 }
196 WARN_ON(buf_len != 0);
197
198 return 0;
199}
200
201static void teardown_sgtable(struct sg_table *sgt)
202{
203 if (sgt->orig_nents > 1)
204 sg_free_table(sgt);
205}
206
207static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
208 void *buf, int buf_len, int in_len, int *pout_len)
209{
210 SYNC_SKCIPHER_REQUEST_ON_STACK(req, key->tfm);
211 struct sg_table sgt;
212 struct scatterlist prealloc_sg;
213 char iv[AES_BLOCK_SIZE] __aligned(8);
214 int pad_byte = AES_BLOCK_SIZE - (in_len & (AES_BLOCK_SIZE - 1));
215 int crypt_len = encrypt ? in_len + pad_byte : in_len;
216 int ret;
217
218 WARN_ON(crypt_len > buf_len);
219 if (encrypt)
220 memset(buf + in_len, pad_byte, pad_byte);
221 ret = setup_sgtable(sgt: &sgt, prealloc_sg: &prealloc_sg, buf, buf_len: crypt_len);
222 if (ret)
223 return ret;
224
225 memcpy(iv, aes_iv, AES_BLOCK_SIZE);
226 skcipher_request_set_sync_tfm(req, tfm: key->tfm);
227 skcipher_request_set_callback(req, flags: 0, NULL, NULL);
228 skcipher_request_set_crypt(req, src: sgt.sgl, dst: sgt.sgl, cryptlen: crypt_len, iv);
229
230 /*
231 print_hex_dump(KERN_ERR, "key: ", DUMP_PREFIX_NONE, 16, 1,
232 key->key, key->len, 1);
233 print_hex_dump(KERN_ERR, " in: ", DUMP_PREFIX_NONE, 16, 1,
234 buf, crypt_len, 1);
235 */
236 if (encrypt)
237 ret = crypto_skcipher_encrypt(req);
238 else
239 ret = crypto_skcipher_decrypt(req);
240 skcipher_request_zero(req);
241 if (ret) {
242 pr_err("%s %scrypt failed: %d\n", __func__,
243 encrypt ? "en" : "de", ret);
244 goto out_sgt;
245 }
246 /*
247 print_hex_dump(KERN_ERR, "out: ", DUMP_PREFIX_NONE, 16, 1,
248 buf, crypt_len, 1);
249 */
250
251 if (encrypt) {
252 *pout_len = crypt_len;
253 } else {
254 pad_byte = *(char *)(buf + in_len - 1);
255 if (pad_byte > 0 && pad_byte <= AES_BLOCK_SIZE &&
256 in_len >= pad_byte) {
257 *pout_len = in_len - pad_byte;
258 } else {
259 pr_err("%s got bad padding %d on in_len %d\n",
260 __func__, pad_byte, in_len);
261 ret = -EPERM;
262 goto out_sgt;
263 }
264 }
265
266out_sgt:
267 teardown_sgtable(sgt: &sgt);
268 return ret;
269}
270
271int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
272 void *buf, int buf_len, int in_len, int *pout_len)
273{
274 switch (key->type) {
275 case CEPH_CRYPTO_NONE:
276 *pout_len = in_len;
277 return 0;
278 case CEPH_CRYPTO_AES:
279 return ceph_aes_crypt(key, encrypt, buf, buf_len, in_len,
280 pout_len);
281 default:
282 return -ENOTSUPP;
283 }
284}
285
286static int ceph_key_preparse(struct key_preparsed_payload *prep)
287{
288 struct ceph_crypto_key *ckey;
289 size_t datalen = prep->datalen;
290 int ret;
291 void *p;
292
293 ret = -EINVAL;
294 if (datalen <= 0 || datalen > 32767 || !prep->data)
295 goto err;
296
297 ret = -ENOMEM;
298 ckey = kmalloc(sizeof(*ckey), GFP_KERNEL);
299 if (!ckey)
300 goto err;
301
302 /* TODO ceph_crypto_key_decode should really take const input */
303 p = (void *)prep->data;
304 ret = ceph_crypto_key_decode(key: ckey, p: &p, end: (char*)prep->data+datalen);
305 if (ret < 0)
306 goto err_ckey;
307
308 prep->payload.data[0] = ckey;
309 prep->quotalen = datalen;
310 return 0;
311
312err_ckey:
313 kfree(objp: ckey);
314err:
315 return ret;
316}
317
318static void ceph_key_free_preparse(struct key_preparsed_payload *prep)
319{
320 struct ceph_crypto_key *ckey = prep->payload.data[0];
321 ceph_crypto_key_destroy(key: ckey);
322 kfree(objp: ckey);
323}
324
325static void ceph_key_destroy(struct key *key)
326{
327 struct ceph_crypto_key *ckey = key->payload.data[0];
328
329 ceph_crypto_key_destroy(key: ckey);
330 kfree(objp: ckey);
331}
332
333struct key_type key_type_ceph = {
334 .name = "ceph",
335 .preparse = ceph_key_preparse,
336 .free_preparse = ceph_key_free_preparse,
337 .instantiate = generic_key_instantiate,
338 .destroy = ceph_key_destroy,
339};
340
341int __init ceph_crypto_init(void)
342{
343 return register_key_type(ktype: &key_type_ceph);
344}
345
346void ceph_crypto_shutdown(void)
347{
348 unregister_key_type(ktype: &key_type_ceph);
349}
350

source code of linux/net/ceph/crypto.c