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         WARN_ON(!key->len);
  41         key->key = kmemdup(buf, key->len, GFP_NOIO);
  42         if (!key->key) {
  43                 ret = -ENOMEM;
  44                 goto fail;
  45         }
  46
  47         /* crypto_alloc_skcipher() allocates with GFP_KERNEL */
  48         noio_flag = memalloc_noio_save();
  49         key->tfm = crypto_alloc_skcipher("cbc(aes)", 0, CRYPTO_ALG_ASYNC);
  50         memalloc_noio_restore(noio_flag);
  51         if (IS_ERR(key->tfm)) {
  52                 ret = PTR_ERR(key->tfm);
  53                 key->tfm = NULL;
  54                 goto fail;
  55         }
  56
  57         ret = crypto_skcipher_setkey(key->tfm, key->key, key->len);
  58         if (ret)
  59                 goto fail;
  60
  61         return 0;
  62
  63 fail:
  64         ceph_crypto_key_destroy(key);
  65         return ret;
  66 }
  67
  68 int ceph_crypto_key_clone(struct ceph_crypto_key *dst,
  69                           const struct ceph_crypto_key *src)
  70 {
  71         memcpy(dst, src, sizeof(struct ceph_crypto_key));
  72         return set_secret(dst, src->key);
  73 }
  74
  75 int ceph_crypto_key_encode(struct ceph_crypto_key *key, void **p, void *end)
  76 {
  77         if (*p + sizeof(u16) + sizeof(key->created) +
  78             sizeof(u16) + key->len > end)
  79                 return -ERANGE;
  80         ceph_encode_16(p, key->type);
  81         ceph_encode_copy(p, &key->created, sizeof(key->created));
  82         ceph_encode_16(p, key->len);
  83         ceph_encode_copy(p, key->key, key->len);
  84         return 0;
  85 }
  86
  87 int ceph_crypto_key_decode(struct ceph_crypto_key *key, void **p, void *end)
  88 {
  89         int ret;
  90
  91         ceph_decode_need(p, end, 2*sizeof(u16) + sizeof(key->created), bad);
  92         key->type = ceph_decode_16(p);
  93         ceph_decode_copy(p, &key->created, sizeof(key->created));
  94         key->len = ceph_decode_16(p);
  95         ceph_decode_need(p, end, key->len, bad);
  96         ret = set_secret(key, *p);
  97         *p += key->len;
  98         return ret;
  99
 100 bad:
 101         dout("failed to decode crypto key\n");
 102         return -EINVAL;
 103 }
 104
 105 int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *inkey)
 106 {
 107         int inlen = strlen(inkey);
 108         int blen = inlen * 3 / 4;
 109         void *buf, *p;
 110         int ret;
 111
 112         dout("crypto_key_unarmor %s\n", inkey);
 113         buf = kmalloc(blen, GFP_NOFS);
 114         if (!buf)
 115                 return -ENOMEM;
 116         blen = ceph_unarmor(buf, inkey, inkey+inlen);
 117         if (blen < 0) {
 118                 kfree(buf);
 119                 return blen;
 120         }
 121
 122         p = buf;
 123         ret = ceph_crypto_key_decode(key, &p, p + blen);
 124         kfree(buf);
 125         if (ret)
 126                 return ret;
 127         dout("crypto_key_unarmor key %p type %d len %d\n", key,
 128              key->type, key->len);
 129         return 0;
 130 }
 131
 132 void ceph_crypto_key_destroy(struct ceph_crypto_key *key)
 133 {
 134         if (key) {
 135                 kfree(key->key);
 136                 key->key = NULL;
 137                 crypto_free_skcipher(key->tfm);
 138                 key->tfm = NULL;
 139         }
 140 }
 141
 142 static const u8 *aes_iv = (u8 *)CEPH_AES_IV;
 143
 144 /*
 145  * Should be used for buffers allocated with ceph_kvmalloc().
 146  * Currently these are encrypt out-buffer (ceph_buffer) and decrypt
 147  * in-buffer (msg front).
 148  *
 149  * Dispose of @sgt with teardown_sgtable().
 150  *
 151  * @prealloc_sg is to avoid memory allocation inside sg_alloc_table()
 152  * in cases where a single sg is sufficient.  No attempt to reduce the
 153  * number of sgs by squeezing physically contiguous pages together is
 154  * made though, for simplicity.
 155  */
 156 static int setup_sgtable(struct sg_table *sgt, struct scatterlist *prealloc_sg,
 157                          const void *buf, unsigned int buf_len)
 158 {
 159         struct scatterlist *sg;
 160         const bool is_vmalloc = is_vmalloc_addr(buf);
 161         unsigned int off = offset_in_page(buf);
 162         unsigned int chunk_cnt = 1;
 163         unsigned int chunk_len = PAGE_ALIGN(off + buf_len);
 164         int i;
 165         int ret;
 166
 167         if (buf_len == 0) {
 168                 memset(sgt, 0, sizeof(*sgt));
 169                 return -EINVAL;
 170         }
 171
 172         if (is_vmalloc) {
 173                 chunk_cnt = chunk_len >> PAGE_SHIFT;
 174                 chunk_len = PAGE_SIZE;
 175         }
 176
 177         if (chunk_cnt > 1) {
 178                 ret = sg_alloc_table(sgt, chunk_cnt, GFP_NOFS);
 179                 if (ret)
 180                         return ret;
 181         } else {
 182                 WARN_ON(chunk_cnt != 1);
 183                 sg_init_table(prealloc_sg, 1);
 184                 sgt->sgl = prealloc_sg;
 185                 sgt->nents = sgt->orig_nents = 1;
 186         }
 187
 188         for_each_sg(sgt->sgl, sg, sgt->orig_nents, i) {
 189                 struct page *page;
 190                 unsigned int len = min(chunk_len - off, buf_len);
 191
 192                 if (is_vmalloc)
 193                         page = vmalloc_to_page(buf);
 194                 else
 195                         page = virt_to_page(buf);
 196
 197                 sg_set_page(sg, page, len, off);
 198
 199                 off = 0;
 200                 buf += len;
 201                 buf_len -= len;
 202         }
 203         WARN_ON(buf_len != 0);
 204
 205         return 0;
 206 }
 207
 208 static void teardown_sgtable(struct sg_table *sgt)
 209 {
 210         if (sgt->orig_nents > 1)
 211                 sg_free_table(sgt);
 212 }
 213
 214 static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
 215                           void *buf, int buf_len, int in_len, int *pout_len)
 216 {
 217         SKCIPHER_REQUEST_ON_STACK(req, key->tfm);
 218         struct sg_table sgt;
 219         struct scatterlist prealloc_sg;
 220         char iv[AES_BLOCK_SIZE] __aligned(8);
 221         int pad_byte = AES_BLOCK_SIZE - (in_len & (AES_BLOCK_SIZE - 1));
 222         int crypt_len = encrypt ? in_len + pad_byte : in_len;
 223         int ret;
 224
 225         WARN_ON(crypt_len > buf_len);
 226         if (encrypt)
 227                 memset(buf + in_len, pad_byte, pad_byte);
 228         ret = setup_sgtable(&sgt, &prealloc_sg, buf, crypt_len);
 229         if (ret)
 230                 return ret;
 231
 232         memcpy(iv, aes_iv, AES_BLOCK_SIZE);
 233         skcipher_request_set_tfm(req, key->tfm);
 234         skcipher_request_set_callback(req, 0, NULL, NULL);
 235         skcipher_request_set_crypt(req, sgt.sgl, sgt.sgl, crypt_len, iv);
 236
 237         /*
 238         print_hex_dump(KERN_ERR, "key: ", DUMP_PREFIX_NONE, 16, 1,
 239                        key->key, key->len, 1);
 240         print_hex_dump(KERN_ERR, " in: ", DUMP_PREFIX_NONE, 16, 1,
 241                        buf, crypt_len, 1);
 242         */
 243         if (encrypt)
 244                 ret = crypto_skcipher_encrypt(req);
 245         else
 246                 ret = crypto_skcipher_decrypt(req);
 247         skcipher_request_zero(req);
 248         if (ret) {
 249                 pr_err("%s %scrypt failed: %d\n", __func__,
 250                        encrypt ? "en" : "de", ret);
 251                 goto out_sgt;
 252         }
 253         /*
 254         print_hex_dump(KERN_ERR, "out: ", DUMP_PREFIX_NONE, 16, 1,
 255                        buf, crypt_len, 1);
 256         */
 257
 258         if (encrypt) {
 259                 *pout_len = crypt_len;
 260         } else {
 261                 pad_byte = *(char *)(buf + in_len - 1);
 262                 if (pad_byte > 0 && pad_byte <= AES_BLOCK_SIZE &&
 263                     in_len >= pad_byte) {
 264                         *pout_len = in_len - pad_byte;
 265                 } else {
 266                         pr_err("%s got bad padding %d on in_len %d\n",
 267                                __func__, pad_byte, in_len);
 268                         ret = -EPERM;
 269                         goto out_sgt;
 270                 }
 271         }
 272
 273 out_sgt:
 274         teardown_sgtable(&sgt);
 275         return ret;
 276 }
 277
 278 int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
 279                void *buf, int buf_len, int in_len, int *pout_len)
 280 {
 281         switch (key->type) {
 282         case CEPH_CRYPTO_NONE:
 283                 *pout_len = in_len;
 284                 return 0;
 285         case CEPH_CRYPTO_AES:
 286                 return ceph_aes_crypt(key, encrypt, buf, buf_len, in_len,
 287                                       pout_len);
 288         default:
 289                 return -ENOTSUPP;
 290         }
 291 }
 292
 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         int ret;
 298         void *p;
 299
 300         ret = -EINVAL;
 301         if (datalen <= 0 || datalen > 32767 || !prep->data)
 302                 goto err;
 303
 304         ret = -ENOMEM;
 305         ckey = kmalloc(sizeof(*ckey), GFP_KERNEL);
 306         if (!ckey)
 307                 goto err;
 308
 309         /* TODO ceph_crypto_key_decode should really take const input */
 310         p = (void *)prep->data;
 311         ret = ceph_crypto_key_decode(ckey, &p, (char*)prep->data+datalen);
 312         if (ret < 0)
 313                 goto err_ckey;
 314
 315         prep->payload.data[0] = ckey;
 316         prep->quotalen = datalen;
 317         return 0;
 318
 319 err_ckey:
 320         kfree(ckey);
 321 err:
 322         return ret;
 323 }
 324
 325 static void ceph_key_free_preparse(struct key_preparsed_payload *prep)
 326 {
 327         struct ceph_crypto_key *ckey = prep->payload.data[0];
 328         ceph_crypto_key_destroy(ckey);
 329         kfree(ckey);
 330 }
 331
 332 static void ceph_key_destroy(struct key *key)
 333 {
 334         struct ceph_crypto_key *ckey = key->payload.data[0];
 335
 336         ceph_crypto_key_destroy(ckey);
 337         kfree(ckey);
 338 }
 339
 340 struct key_type key_type_ceph = {
 341         .name           = "ceph",
 342         .preparse       = ceph_key_preparse,
 343         .free_preparse  = ceph_key_free_preparse,
 344         .instantiate    = generic_key_instantiate,
 345         .destroy        = ceph_key_destroy,
 346 };
 347
 348 int ceph_crypto_init(void) {
 349         return register_key_type(&key_type_ceph);
 350 }
 351
 352 void ceph_crypto_shutdown(void) {
 353         unregister_key_type(&key_type_ceph);
 354 }