net/ceph/crypto.c

   1
   2 #include <linux/ceph/ceph_debug.h>
   3
   4 #include <linux/err.h>
   5 #include <linux/scatterlist.h>
   6 #include <linux/slab.h>
   7 #include <crypto/aes.h>
   8 #include <crypto/skcipher.h>
   9 #include <linux/key-type.h>
  10
  11 #include <keys/ceph-type.h>
  12 #include <keys/user-type.h>
  13 #include <linux/ceph/decode.h>
  14 #include "crypto.h"
  15
  16 /*
  17  * Set ->key and ->tfm.  The rest of the key should be filled in before
  18  * this function is called.
  19  */
  20 static int set_secret(struct ceph_crypto_key *key, void *buf)
  21 {
  22         unsigned int noio_flag;
  23         int ret;
  24
  25         key->key = NULL;
  26         key->tfm = NULL;
  27
  28         switch (key->type) {
  29         case CEPH_CRYPTO_NONE:
  30                 return 0; /* nothing to do */
  31         case CEPH_CRYPTO_AES:
  32                 break;
  33         default:
  34                 return -ENOTSUPP;
  35         }
  36
  37         WARN_ON(!key->len);
  38         key->key = kmemdup(buf, key->len, GFP_NOIO);
  39         if (!key->key) {
  40                 ret = -ENOMEM;
  41                 goto fail;
  42         }
  43
  44         /* crypto_alloc_skcipher() allocates with GFP_KERNEL */
  45         noio_flag = memalloc_noio_save();
  46         key->tfm = crypto_alloc_skcipher("cbc(aes)", 0, CRYPTO_ALG_ASYNC);
  47         memalloc_noio_restore(noio_flag);
  48         if (IS_ERR(key->tfm)) {
  49                 ret = PTR_ERR(key->tfm);
  50                 key->tfm = NULL;
  51                 goto fail;
  52         }
  53
  54         ret = crypto_skcipher_setkey(key->tfm, key->key, key->len);
  55         if (ret)
  56                 goto fail;
  57
  58         return 0;
  59
  60 fail:
  61         ceph_crypto_key_destroy(key);
  62         return ret;
  63 }
  64
  65 int ceph_crypto_key_clone(struct ceph_crypto_key *dst,
  66                           const struct ceph_crypto_key *src)
  67 {
  68         memcpy(dst, src, sizeof(struct ceph_crypto_key));
  69         return set_secret(dst, src->key);
  70 }
  71
  72 int ceph_crypto_key_encode(struct ceph_crypto_key *key, void **p, void *end)
  73 {
  74         if (*p + sizeof(u16) + sizeof(key->created) +
  75             sizeof(u16) + key->len > end)
  76                 return -ERANGE;
  77         ceph_encode_16(p, key->type);
  78         ceph_encode_copy(p, &key->created, sizeof(key->created));
  79         ceph_encode_16(p, key->len);
  80         ceph_encode_copy(p, key->key, key->len);
  81         return 0;
  82 }
  83
  84 int ceph_crypto_key_decode(struct ceph_crypto_key *key, void **p, void *end)
  85 {
  86         int ret;
  87
  88         ceph_decode_need(p, end, 2*sizeof(u16) + sizeof(key->created), bad);
  89         key->type = ceph_decode_16(p);
  90         ceph_decode_copy(p, &key->created, sizeof(key->created));
  91         key->len = ceph_decode_16(p);
  92         ceph_decode_need(p, end, key->len, bad);
  93         ret = set_secret(key, *p);
  94         *p += key->len;
  95         return ret;
  96
  97 bad:
  98         dout("failed to decode crypto key\n");
  99         return -EINVAL;
 100 }
 101
 102 int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *inkey)
 103 {
 104         int inlen = strlen(inkey);
 105         int blen = inlen * 3 / 4;
 106         void *buf, *p;
 107         int ret;
 108
 109         dout("crypto_key_unarmor %s\n", inkey);
 110         buf = kmalloc(blen, GFP_NOFS);
 111         if (!buf)
 112                 return -ENOMEM;
 113         blen = ceph_unarmor(buf, inkey, inkey+inlen);
 114         if (blen < 0) {
 115                 kfree(buf);
 116                 return blen;
 117         }
 118
 119         p = buf;
 120         ret = ceph_crypto_key_decode(key, &p, p + blen);
 121         kfree(buf);
 122         if (ret)
 123                 return ret;
 124         dout("crypto_key_unarmor key %p type %d len %d\n", key,
 125              key->type, key->len);
 126         return 0;
 127 }
 128
 129 void ceph_crypto_key_destroy(struct ceph_crypto_key *key)
 130 {
 131         if (key) {
 132                 kfree(key->key);
 133                 key->key = NULL;
 134                 crypto_free_skcipher(key->tfm);
 135                 key->tfm = NULL;
 136         }
 137 }
 138
 139 static const u8 *aes_iv = (u8 *)CEPH_AES_IV;
 140
 141 /*
 142  * Should be used for buffers allocated with ceph_kvmalloc().
 143  * Currently these are encrypt out-buffer (ceph_buffer) and decrypt
 144  * in-buffer (msg front).
 145  *
 146  * Dispose of @sgt with teardown_sgtable().
 147  *
 148  * @prealloc_sg is to avoid memory allocation inside sg_alloc_table()
 149  * in cases where a single sg is sufficient.  No attempt to reduce the
 150  * number of sgs by squeezing physically contiguous pages together is
 151  * made though, for simplicity.
 152  */
 153 static int setup_sgtable(struct sg_table *sgt, struct scatterlist *prealloc_sg,
 154                          const void *buf, unsigned int buf_len)
 155 {
 156         struct scatterlist *sg;
 157         const bool is_vmalloc = is_vmalloc_addr(buf);
 158         unsigned int off = offset_in_page(buf);
 159         unsigned int chunk_cnt = 1;
 160         unsigned int chunk_len = PAGE_ALIGN(off + buf_len);
 161         int i;
 162         int ret;
 163
 164         if (buf_len == 0) {
 165                 memset(sgt, 0, sizeof(*sgt));
 166                 return -EINVAL;
 167         }
 168
 169         if (is_vmalloc) {
 170                 chunk_cnt = chunk_len >> PAGE_SHIFT;
 171                 chunk_len = PAGE_SIZE;
 172         }
 173
 174         if (chunk_cnt > 1) {
 175                 ret = sg_alloc_table(sgt, chunk_cnt, GFP_NOFS);
 176                 if (ret)
 177                         return ret;
 178         } else {
 179                 WARN_ON(chunk_cnt != 1);
 180                 sg_init_table(prealloc_sg, 1);
 181                 sgt->sgl = prealloc_sg;
 182                 sgt->nents = sgt->orig_nents = 1;
 183         }
 184
 185         for_each_sg(sgt->sgl, sg, sgt->orig_nents, i) {
 186                 struct page *page;
 187                 unsigned int len = min(chunk_len - off, buf_len);
 188
 189                 if (is_vmalloc)
 190                         page = vmalloc_to_page(buf);
 191                 else
 192                         page = virt_to_page(buf);
 193
 194                 sg_set_page(sg, page, len, off);
 195
 196                 off = 0;
 197                 buf += len;
 198                 buf_len -= len;
 199         }
 200         WARN_ON(buf_len != 0);
 201
 202         return 0;
 203 }
 204
 205 static void teardown_sgtable(struct sg_table *sgt)
 206 {
 207         if (sgt->orig_nents > 1)
 208                 sg_free_table(sgt);
 209 }
 210
 211 static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
 212                           void *buf, int buf_len, int in_len, int *pout_len)
 213 {
 214         SKCIPHER_REQUEST_ON_STACK(req, key->tfm);
 215         struct sg_table sgt;
 216         struct scatterlist prealloc_sg;
 217         char iv[AES_BLOCK_SIZE] __aligned(8);
 218         int pad_byte = AES_BLOCK_SIZE - (in_len & (AES_BLOCK_SIZE - 1));
 219         int crypt_len = encrypt ? in_len + pad_byte : in_len;
 220         int ret;
 221
 222         WARN_ON(crypt_len > buf_len);
 223         if (encrypt)
 224                 memset(buf + in_len, pad_byte, pad_byte);
 225         ret = setup_sgtable(&sgt, &prealloc_sg, buf, crypt_len);
 226         if (ret)
 227                 return ret;
 228
 229         memcpy(iv, aes_iv, AES_BLOCK_SIZE);
 230         skcipher_request_set_tfm(req, key->tfm);
 231         skcipher_request_set_callback(req, 0, NULL, NULL);
 232         skcipher_request_set_crypt(req, sgt.sgl, sgt.sgl, crypt_len, iv);
 233
 234         /*
 235         print_hex_dump(KERN_ERR, "key: ", DUMP_PREFIX_NONE, 16, 1,
 236                        key->key, key->len, 1);
 237         print_hex_dump(KERN_ERR, " in: ", DUMP_PREFIX_NONE, 16, 1,
 238                        buf, crypt_len, 1);
 239         */
 240         if (encrypt)
 241                 ret = crypto_skcipher_encrypt(req);
 242         else
 243                 ret = crypto_skcipher_decrypt(req);
 244         skcipher_request_zero(req);
 245         if (ret) {
 246                 pr_err("%s %scrypt failed: %d\n", __func__,
 247                        encrypt ? "en" : "de", ret);
 248                 goto out_sgt;
 249         }
 250         /*
 251         print_hex_dump(KERN_ERR, "out: ", DUMP_PREFIX_NONE, 16, 1,
 252                        buf, crypt_len, 1);
 253         */
 254
 255         if (encrypt) {
 256                 *pout_len = crypt_len;
 257         } else {
 258                 pad_byte = *(char *)(buf + in_len - 1);
 259                 if (pad_byte > 0 && pad_byte <= AES_BLOCK_SIZE &&
 260                     in_len >= pad_byte) {
 261                         *pout_len = in_len - pad_byte;
 262                 } else {
 263                         pr_err("%s got bad padding %d on in_len %d\n",
 264                                __func__, pad_byte, in_len);
 265                         ret = -EPERM;
 266                         goto out_sgt;
 267                 }
 268         }
 269
 270 out_sgt:
 271         teardown_sgtable(&sgt);
 272         return ret;
 273 }
 274
 275 int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
 276                void *buf, int buf_len, int in_len, int *pout_len)
 277 {
 278         switch (key->type) {
 279         case CEPH_CRYPTO_NONE:
 280                 *pout_len = in_len;
 281                 return 0;
 282         case CEPH_CRYPTO_AES:
 283                 return ceph_aes_crypt(key, encrypt, buf, buf_len, in_len,
 284                                       pout_len);
 285         default:
 286                 return -ENOTSUPP;
 287         }
 288 }
 289
 290 static int ceph_key_preparse(struct key_preparsed_payload *prep)
 291 {
 292         struct ceph_crypto_key *ckey;
 293         size_t datalen = prep->datalen;
 294         int ret;
 295         void *p;
 296
 297         ret = -EINVAL;
 298         if (datalen <= 0 || datalen > 32767 || !prep->data)
 299                 goto err;
 300
 301         ret = -ENOMEM;
 302         ckey = kmalloc(sizeof(*ckey), GFP_KERNEL);
 303         if (!ckey)
 304                 goto err;
 305
 306         /* TODO ceph_crypto_key_decode should really take const input */
 307         p = (void *)prep->data;
 308         ret = ceph_crypto_key_decode(ckey, &p, (char*)prep->data+datalen);
 309         if (ret < 0)
 310                 goto err_ckey;
 311
 312         prep->payload.data[0] = ckey;
 313         prep->quotalen = datalen;
 314         return 0;
 315
 316 err_ckey:
 317         kfree(ckey);
 318 err:
 319         return ret;
 320 }
 321
 322 static void ceph_key_free_preparse(struct key_preparsed_payload *prep)
 323 {
 324         struct ceph_crypto_key *ckey = prep->payload.data[0];
 325         ceph_crypto_key_destroy(ckey);
 326         kfree(ckey);
 327 }
 328
 329 static void ceph_key_destroy(struct key *key)
 330 {
 331         struct ceph_crypto_key *ckey = key->payload.data[0];
 332
 333         ceph_crypto_key_destroy(ckey);
 334         kfree(ckey);
 335 }
 336
 337 struct key_type key_type_ceph = {
 338         .name           = "ceph",
 339         .preparse       = ceph_key_preparse,
 340         .free_preparse  = ceph_key_free_preparse,
 341         .instantiate    = generic_key_instantiate,
 342         .destroy        = ceph_key_destroy,
 343 };
 344
 345 int ceph_crypto_init(void) {
 346         return register_key_type(&key_type_ceph);
 347 }
 348
 349 void ceph_crypto_shutdown(void) {
 350         unregister_key_type(&key_type_ceph);
 351 }