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  */
set_secret(struct ceph_crypto_key * key,void * buf)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 
ceph_crypto_key_clone(struct ceph_crypto_key * dst,const struct ceph_crypto_key * src)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 
ceph_crypto_key_encode(struct ceph_crypto_key * key,void ** p,void * end)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 
ceph_crypto_key_decode(struct ceph_crypto_key * key,void ** p,void * end)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 
ceph_crypto_key_unarmor(struct ceph_crypto_key * key,const char * inkey)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 
ceph_crypto_key_destroy(struct ceph_crypto_key * key)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  */
setup_sgtable(struct sg_table * sgt,struct scatterlist * prealloc_sg,const void * buf,unsigned int buf_len)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 
teardown_sgtable(struct sg_table * sgt)213 static void teardown_sgtable(struct sg_table *sgt)
214 {
215 	if (sgt->orig_nents > 1)
216 		sg_free_table(sgt);
217 }
218 
ceph_aes_crypt(const struct ceph_crypto_key * key,bool encrypt,void * buf,int buf_len,int in_len,int * pout_len)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 
ceph_crypt(const struct ceph_crypto_key * key,bool encrypt,void * buf,int buf_len,int in_len,int * pout_len)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 
ceph_key_preparse(struct key_preparsed_payload * prep)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 
ceph_key_free_preparse(struct key_preparsed_payload * prep)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 
ceph_key_destroy(struct key * key)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 
ceph_crypto_init(void)353 int __init ceph_crypto_init(void)
354 {
355 	return register_key_type(&key_type_ceph);
356 }
357 
ceph_crypto_shutdown(void)358 void ceph_crypto_shutdown(void)
359 {
360 	unregister_key_type(&key_type_ceph);
361 }
362