crypto.c 7.9 KB
Newer Older
1
// SPDX-License-Identifier: GPL-2.0
2

3
#include <linux/ceph/ceph_debug.h>
4 5 6

#include <linux/err.h>
#include <linux/scatterlist.h>
7
#include <linux/sched.h>
8
#include <linux/slab.h>
H
Herbert Xu 已提交
9 10
#include <crypto/aes.h>
#include <crypto/skcipher.h>
11
#include <linux/key-type.h>
12
#include <linux/sched/mm.h>
13

14
#include <keys/ceph-type.h>
D
David Howells 已提交
15
#include <keys/user-type.h>
16
#include <linux/ceph/decode.h>
17 18
#include "crypto.h"

19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67
/*
 * Set ->key and ->tfm.  The rest of the key should be filled in before
 * this function is called.
 */
static int set_secret(struct ceph_crypto_key *key, void *buf)
{
	unsigned int noio_flag;
	int ret;

	key->key = NULL;
	key->tfm = NULL;

	switch (key->type) {
	case CEPH_CRYPTO_NONE:
		return 0; /* nothing to do */
	case CEPH_CRYPTO_AES:
		break;
	default:
		return -ENOTSUPP;
	}

	WARN_ON(!key->len);
	key->key = kmemdup(buf, key->len, GFP_NOIO);
	if (!key->key) {
		ret = -ENOMEM;
		goto fail;
	}

	/* crypto_alloc_skcipher() allocates with GFP_KERNEL */
	noio_flag = memalloc_noio_save();
	key->tfm = crypto_alloc_skcipher("cbc(aes)", 0, CRYPTO_ALG_ASYNC);
	memalloc_noio_restore(noio_flag);
	if (IS_ERR(key->tfm)) {
		ret = PTR_ERR(key->tfm);
		key->tfm = NULL;
		goto fail;
	}

	ret = crypto_skcipher_setkey(key->tfm, key->key, key->len);
	if (ret)
		goto fail;

	return 0;

fail:
	ceph_crypto_key_destroy(key);
	return ret;
}

68 69 70 71
int ceph_crypto_key_clone(struct ceph_crypto_key *dst,
			  const struct ceph_crypto_key *src)
{
	memcpy(dst, src, sizeof(struct ceph_crypto_key));
72
	return set_secret(dst, src->key);
73 74
}

75 76 77 78 79 80 81 82 83 84 85 86 87 88
int ceph_crypto_key_encode(struct ceph_crypto_key *key, void **p, void *end)
{
	if (*p + sizeof(u16) + sizeof(key->created) +
	    sizeof(u16) + key->len > end)
		return -ERANGE;
	ceph_encode_16(p, key->type);
	ceph_encode_copy(p, &key->created, sizeof(key->created));
	ceph_encode_16(p, key->len);
	ceph_encode_copy(p, key->key, key->len);
	return 0;
}

int ceph_crypto_key_decode(struct ceph_crypto_key *key, void **p, void *end)
{
89 90
	int ret;

91 92 93 94 95
	ceph_decode_need(p, end, 2*sizeof(u16) + sizeof(key->created), bad);
	key->type = ceph_decode_16(p);
	ceph_decode_copy(p, &key->created, sizeof(key->created));
	key->len = ceph_decode_16(p);
	ceph_decode_need(p, end, key->len, bad);
96 97 98
	ret = set_secret(key, *p);
	*p += key->len;
	return ret;
99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131

bad:
	dout("failed to decode crypto key\n");
	return -EINVAL;
}

int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *inkey)
{
	int inlen = strlen(inkey);
	int blen = inlen * 3 / 4;
	void *buf, *p;
	int ret;

	dout("crypto_key_unarmor %s\n", inkey);
	buf = kmalloc(blen, GFP_NOFS);
	if (!buf)
		return -ENOMEM;
	blen = ceph_unarmor(buf, inkey, inkey+inlen);
	if (blen < 0) {
		kfree(buf);
		return blen;
	}

	p = buf;
	ret = ceph_crypto_key_decode(key, &p, p + blen);
	kfree(buf);
	if (ret)
		return ret;
	dout("crypto_key_unarmor key %p type %d len %d\n", key,
	     key->type, key->len);
	return 0;
}

132 133 134 135 136
void ceph_crypto_key_destroy(struct ceph_crypto_key *key)
{
	if (key) {
		kfree(key->key);
		key->key = NULL;
137 138
		crypto_free_skcipher(key->tfm);
		key->tfm = NULL;
139 140 141
	}
}

142
static const u8 *aes_iv = (u8 *)CEPH_AES_IV;
143

144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213
/*
 * Should be used for buffers allocated with ceph_kvmalloc().
 * Currently these are encrypt out-buffer (ceph_buffer) and decrypt
 * in-buffer (msg front).
 *
 * Dispose of @sgt with teardown_sgtable().
 *
 * @prealloc_sg is to avoid memory allocation inside sg_alloc_table()
 * in cases where a single sg is sufficient.  No attempt to reduce the
 * number of sgs by squeezing physically contiguous pages together is
 * made though, for simplicity.
 */
static int setup_sgtable(struct sg_table *sgt, struct scatterlist *prealloc_sg,
			 const void *buf, unsigned int buf_len)
{
	struct scatterlist *sg;
	const bool is_vmalloc = is_vmalloc_addr(buf);
	unsigned int off = offset_in_page(buf);
	unsigned int chunk_cnt = 1;
	unsigned int chunk_len = PAGE_ALIGN(off + buf_len);
	int i;
	int ret;

	if (buf_len == 0) {
		memset(sgt, 0, sizeof(*sgt));
		return -EINVAL;
	}

	if (is_vmalloc) {
		chunk_cnt = chunk_len >> PAGE_SHIFT;
		chunk_len = PAGE_SIZE;
	}

	if (chunk_cnt > 1) {
		ret = sg_alloc_table(sgt, chunk_cnt, GFP_NOFS);
		if (ret)
			return ret;
	} else {
		WARN_ON(chunk_cnt != 1);
		sg_init_table(prealloc_sg, 1);
		sgt->sgl = prealloc_sg;
		sgt->nents = sgt->orig_nents = 1;
	}

	for_each_sg(sgt->sgl, sg, sgt->orig_nents, i) {
		struct page *page;
		unsigned int len = min(chunk_len - off, buf_len);

		if (is_vmalloc)
			page = vmalloc_to_page(buf);
		else
			page = virt_to_page(buf);

		sg_set_page(sg, page, len, off);

		off = 0;
		buf += len;
		buf_len -= len;
	}
	WARN_ON(buf_len != 0);

	return 0;
}

static void teardown_sgtable(struct sg_table *sgt)
{
	if (sgt->orig_nents > 1)
		sg_free_table(sgt);
}

214 215 216
static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
			  void *buf, int buf_len, int in_len, int *pout_len)
{
217
	SKCIPHER_REQUEST_ON_STACK(req, key->tfm);
218 219
	struct sg_table sgt;
	struct scatterlist prealloc_sg;
220
	char iv[AES_BLOCK_SIZE] __aligned(8);
221 222 223 224 225 226 227 228 229
	int pad_byte = AES_BLOCK_SIZE - (in_len & (AES_BLOCK_SIZE - 1));
	int crypt_len = encrypt ? in_len + pad_byte : in_len;
	int ret;

	WARN_ON(crypt_len > buf_len);
	if (encrypt)
		memset(buf + in_len, pad_byte, pad_byte);
	ret = setup_sgtable(&sgt, &prealloc_sg, buf, crypt_len);
	if (ret)
230
		return ret;
231 232

	memcpy(iv, aes_iv, AES_BLOCK_SIZE);
233
	skcipher_request_set_tfm(req, key->tfm);
234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sgt.sgl, sgt.sgl, crypt_len, iv);

	/*
	print_hex_dump(KERN_ERR, "key: ", DUMP_PREFIX_NONE, 16, 1,
		       key->key, key->len, 1);
	print_hex_dump(KERN_ERR, " in: ", DUMP_PREFIX_NONE, 16, 1,
		       buf, crypt_len, 1);
	*/
	if (encrypt)
		ret = crypto_skcipher_encrypt(req);
	else
		ret = crypto_skcipher_decrypt(req);
	skcipher_request_zero(req);
	if (ret) {
		pr_err("%s %scrypt failed: %d\n", __func__,
		       encrypt ? "en" : "de", ret);
		goto out_sgt;
	}
	/*
	print_hex_dump(KERN_ERR, "out: ", DUMP_PREFIX_NONE, 16, 1,
		       buf, crypt_len, 1);
	*/

	if (encrypt) {
		*pout_len = crypt_len;
	} else {
		pad_byte = *(char *)(buf + in_len - 1);
		if (pad_byte > 0 && pad_byte <= AES_BLOCK_SIZE &&
		    in_len >= pad_byte) {
			*pout_len = in_len - pad_byte;
		} else {
			pr_err("%s got bad padding %d on in_len %d\n",
			       __func__, pad_byte, in_len);
			ret = -EPERM;
			goto out_sgt;
		}
	}

out_sgt:
	teardown_sgtable(&sgt);
	return ret;
}

int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
	       void *buf, int buf_len, int in_len, int *pout_len)
{
	switch (key->type) {
	case CEPH_CRYPTO_NONE:
		*pout_len = in_len;
		return 0;
	case CEPH_CRYPTO_AES:
		return ceph_aes_crypt(key, encrypt, buf, buf_len, in_len,
				      pout_len);
	default:
		return -ENOTSUPP;
	}
}

D
David Howells 已提交
293
static int ceph_key_preparse(struct key_preparsed_payload *prep)
294 295
{
	struct ceph_crypto_key *ckey;
296
	size_t datalen = prep->datalen;
297 298 299 300
	int ret;
	void *p;

	ret = -EINVAL;
301
	if (datalen <= 0 || datalen > 32767 || !prep->data)
302 303 304 305 306 307 308 309
		goto err;

	ret = -ENOMEM;
	ckey = kmalloc(sizeof(*ckey), GFP_KERNEL);
	if (!ckey)
		goto err;

	/* TODO ceph_crypto_key_decode should really take const input */
310 311
	p = (void *)prep->data;
	ret = ceph_crypto_key_decode(ckey, &p, (char*)prep->data+datalen);
312 313 314
	if (ret < 0)
		goto err_ckey;

315
	prep->payload.data[0] = ckey;
D
David Howells 已提交
316
	prep->quotalen = datalen;
317 318 319 320 321 322 323 324
	return 0;

err_ckey:
	kfree(ckey);
err:
	return ret;
}

D
David Howells 已提交
325 326
static void ceph_key_free_preparse(struct key_preparsed_payload *prep)
{
327
	struct ceph_crypto_key *ckey = prep->payload.data[0];
D
David Howells 已提交
328 329 330 331 332 333
	ceph_crypto_key_destroy(ckey);
	kfree(ckey);
}

static void ceph_key_destroy(struct key *key)
{
334
	struct ceph_crypto_key *ckey = key->payload.data[0];
335 336

	ceph_crypto_key_destroy(ckey);
337
	kfree(ckey);
338 339 340 341
}

struct key_type key_type_ceph = {
	.name		= "ceph",
D
David Howells 已提交
342 343 344
	.preparse	= ceph_key_preparse,
	.free_preparse	= ceph_key_free_preparse,
	.instantiate	= generic_key_instantiate,
345 346 347 348 349 350 351 352 353 354
	.destroy	= ceph_key_destroy,
};

int ceph_crypto_init(void) {
	return register_key_type(&key_type_ceph);
}

void ceph_crypto_shutdown(void) {
	unregister_key_type(&key_type_ceph);
}