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/sched.h>
   7 #include <linux/slab.h>
   8 #include <crypto/aes.h>
   9 #include <crypto/skcipher.h>
  10 #include <linux/key-type.h>
  11 #include <linux/sched/mm.h>
  12
  13 #include <keys/ceph-type.h>
  14 #include <keys/user-type.h>
  15 #include <linux/ceph/decode.h>
  16 #include "crypto.h"
  17
  18 /*
  19  * Set ->key and ->tfm.  The rest of the key should be filled in before
  20  * this function is called.
  21  */
  22 static int set_secret(struct ceph_crypto_key *key, void *buf)
  23 {
  24         unsigned int noio_flag;
  25         int ret;
  26
  27         key->key = NULL;
  28         key->tfm = NULL;
  29
  30         switch (key->type) {
  31         case CEPH_CRYPTO_NONE:
  32                 return 0; /* nothing to do */
  33         case CEPH_CRYPTO_AES:
  34                 break;
  35         default:
  36                 return -ENOTSUPP;
  37         }
  38
  39         WARN_ON(!key->len);
  40         key->key = kmemdup(buf, key->len, GFP_NOIO);
  41         if (!key->key) {
  42                 ret = -ENOMEM;
  43                 goto fail;
  44         }
  45
  46         /* crypto_alloc_skcipher() allocates with GFP_KERNEL */
  47         noio_flag = memalloc_noio_save();
  48         key->tfm = crypto_alloc_skcipher("cbc(aes)", 0, CRYPTO_ALG_ASYNC);
  49         memalloc_noio_restore(noio_flag);
  50         if (IS_ERR(key->tfm)) {
  51                 ret = PTR_ERR(key->tfm);
  52                 key->tfm = NULL;
  53                 goto fail;
  54         }
  55
  56         ret = crypto_skcipher_setkey(key->tfm, key->key, key->len);
  57         if (ret)
  58                 goto fail;
  59
  60         return 0;
  61
  62 fail:
  63         ceph_crypto_key_destroy(key);
  64         return ret;
  65 }
  66
  67 int ceph_crypto_key_clone(struct ceph_crypto_key *dst,
  68                           const struct ceph_crypto_key *src)
  69 {
  70         memcpy(dst, src, sizeof(struct ceph_crypto_key));
  71         return set_secret(dst, src->key);
  72 }
  73
  74 int ceph_crypto_key_encode(struct ceph_crypto_key *key, void **p, void *end)
  75 {
  76         if (*p + sizeof(u16) + sizeof(key->created) +
  77             sizeof(u16) + key->len > end)
  78                 return -ERANGE;
  79         ceph_encode_16(p, key->type);
  80         ceph_encode_copy(p, &key->created, sizeof(key->created));
  81         ceph_encode_16(p, key->len);
  82         ceph_encode_copy(p, key->key, key->len);
  83         return 0;
  84 }
  85
  86 int ceph_crypto_key_decode(struct ceph_crypto_key *key, void **p, void *end)
  87 {
  88         int ret;
  89
  90         ceph_decode_need(p, end, 2*sizeof(u16) + sizeof(key->created), bad);
  91         key->type = ceph_decode_16(p);
  92         ceph_decode_copy(p, &key->created, sizeof(key->created));
  93         key->len = ceph_decode_16(p);
  94         ceph_decode_need(p, end, key->len, bad);
  95         ret = set_secret(key, *p);
  96         *p += key->len;
  97         return ret;
  98
  99 bad:
 100         dout("failed to decode crypto key\n");
 101         return -EINVAL;
 102 }
 103
 104 int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *inkey)
 105 {
 106         int inlen = strlen(inkey);
 107         int blen = inlen * 3 / 4;
 108         void *buf, *p;
 109         int ret;
 110
 111         dout("crypto_key_unarmor %s\n", inkey);
 112         buf = kmalloc(blen, GFP_NOFS);
 113         if (!buf)
 114                 return -ENOMEM;
 115         blen = ceph_unarmor(buf, inkey, inkey+inlen);
 116         if (blen < 0) {
 117                 kfree(buf);
 118                 return blen;
 119         }
 120
 121         p = buf;
 122         ret = ceph_crypto_key_decode(key, &p, p + blen);
 123         kfree(buf);
 124         if (ret)
 125                 return ret;
 126         dout("crypto_key_unarmor key %p type %d len %d\n", key,
 127              key->type, key->len);
 128         return 0;
 129 }
 130
 131 void ceph_crypto_key_destroy(struct ceph_crypto_key *key)
 132 {
 133         if (key) {
 134                 kfree(key->key);
 135                 key->key = NULL;
 136                 crypto_free_skcipher(key->tfm);
 137                 key->tfm = NULL;
 138         }
 139 }
 140
 141 static const u8 *aes_iv = (u8 *)CEPH_AES_IV;
 142
 143 /*
 144  * Should be used for buffers allocated with ceph_kvmalloc().
 145  * Currently these are encrypt out-buffer (ceph_buffer) and decrypt
 146  * in-buffer (msg front).
 147  *
 148  * Dispose of @sgt with teardown_sgtable().
 149  *
 150  * @prealloc_sg is to avoid memory allocation inside sg_alloc_table()
 151  * in cases where a single sg is sufficient.  No attempt to reduce the
 152  * number of sgs by squeezing physically contiguous pages together is
 153  * made though, for simplicity.
 154  */
 155 static int setup_sgtable(struct sg_table *sgt, struct scatterlist *prealloc_sg,
 156                          const void *buf, unsigned int buf_len)
 157 {
 158         struct scatterlist *sg;
 159         const bool is_vmalloc = is_vmalloc_addr(buf);
 160         unsigned int off = offset_in_page(buf);
 161         unsigned int chunk_cnt = 1;
 162         unsigned int chunk_len = PAGE_ALIGN(off + buf_len);
 163         int i;
 164         int ret;
 165
 166         if (buf_len == 0) {
 167                 memset(sgt, 0, sizeof(*sgt));
 168                 return -EINVAL;
 169         }
 170
 171         if (is_vmalloc) {
 172                 chunk_cnt = chunk_len >> PAGE_SHIFT;
 173                 chunk_len = PAGE_SIZE;
 174         }
 175
 176         if (chunk_cnt > 1) {
 177                 ret = sg_alloc_table(sgt, chunk_cnt, GFP_NOFS);
 178                 if (ret)
 179                         return ret;
 180         } else {
 181                 WARN_ON(chunk_cnt != 1);
 182                 sg_init_table(prealloc_sg, 1);
 183                 sgt->sgl = prealloc_sg;
 184                 sgt->nents = sgt->orig_nents = 1;
 185         }
 186
 187         for_each_sg(sgt->sgl, sg, sgt->orig_nents, i) {
 188                 struct page *page;
 189                 unsigned int len = min(chunk_len - off, buf_len);
 190
 191                 if (is_vmalloc)
 192                         page = vmalloc_to_page(buf);
 193                 else
 194                         page = virt_to_page(buf);
 195
 196                 sg_set_page(sg, page, len, off);
 197
 198                 off = 0;
 199                 buf += len;
 200                 buf_len -= len;
 201         }
 202         WARN_ON(buf_len != 0);
 203
 204         return 0;
 205 }
 206
 207 static void teardown_sgtable(struct sg_table *sgt)
 208 {
 209         if (sgt->orig_nents > 1)
 210                 sg_free_table(sgt);
 211 }
 212
 213 static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
 214                           void *buf, int buf_len, int in_len, int *pout_len)
 215 {
 216         SKCIPHER_REQUEST_ON_STACK(req, key->tfm);
 217         struct sg_table sgt;
 218         struct scatterlist prealloc_sg;
 219         char iv[AES_BLOCK_SIZE] __aligned(8);
 220         int pad_byte = AES_BLOCK_SIZE - (in_len & (AES_BLOCK_SIZE - 1));
 221         int crypt_len = encrypt ? in_len + pad_byte : in_len;
 222         int ret;
 223
 224         WARN_ON(crypt_len > buf_len);
 225         if (encrypt)
 226                 memset(buf + in_len, pad_byte, pad_byte);
 227         ret = setup_sgtable(&sgt, &prealloc_sg, buf, crypt_len);
 228         if (ret)
 229                 return ret;
 230
 231         memcpy(iv, aes_iv, AES_BLOCK_SIZE);
 232         skcipher_request_set_tfm(req, key->tfm);
 233         skcipher_request_set_callback(req, 0, NULL, NULL);
 234         skcipher_request_set_crypt(req, sgt.sgl, sgt.sgl, crypt_len, iv);
 235
 236         /*
 237         print_hex_dump(KERN_ERR, "key: ", DUMP_PREFIX_NONE, 16, 1,
 238                        key->key, key->len, 1);
 239         print_hex_dump(KERN_ERR, " in: ", DUMP_PREFIX_NONE, 16, 1,
 240                        buf, crypt_len, 1);
 241         */
 242         if (encrypt)
 243                 ret = crypto_skcipher_encrypt(req);
 244         else
 245                 ret = crypto_skcipher_decrypt(req);
 246         skcipher_request_zero(req);
 247         if (ret) {
 248                 pr_err("%s %scrypt failed: %d\n", __func__,
 249                        encrypt ? "en" : "de", ret);
 250                 goto out_sgt;
 251         }
 252         /*
 253         print_hex_dump(KERN_ERR, "out: ", DUMP_PREFIX_NONE, 16, 1,
 254                        buf, crypt_len, 1);
 255         */
 256
 257         if (encrypt) {
 258                 *pout_len = crypt_len;
 259         } else {
 260                 pad_byte = *(char *)(buf + in_len - 1);
 261                 if (pad_byte > 0 && pad_byte <= AES_BLOCK_SIZE &&
 262                     in_len >= pad_byte) {
 263                         *pout_len = in_len - pad_byte;
 264                 } else {
 265                         pr_err("%s got bad padding %d on in_len %d\n",
 266                                __func__, pad_byte, in_len);
 267                         ret = -EPERM;
 268                         goto out_sgt;
 269                 }
 270         }
 271
 272 out_sgt:
 273         teardown_sgtable(&sgt);
 274         return ret;
 275 }
 276
 277 int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
 278                void *buf, int buf_len, int in_len, int *pout_len)
 279 {
 280         switch (key->type) {
 281         case CEPH_CRYPTO_NONE:
 282                 *pout_len = in_len;
 283                 return 0;
 284         case CEPH_CRYPTO_AES:
 285                 return ceph_aes_crypt(key, encrypt, buf, buf_len, in_len,
 286                                       pout_len);
 287         default:
 288                 return -ENOTSUPP;
 289         }
 290 }
 291
 292 static int ceph_key_preparse(struct key_preparsed_payload *prep)
 293 {
 294         struct ceph_crypto_key *ckey;
 295         size_t datalen = prep->datalen;
 296         int ret;
 297         void *p;
 298
 299         ret = -EINVAL;
 300         if (datalen <= 0 || datalen > 32767 || !prep->data)
 301                 goto err;
 302
 303         ret = -ENOMEM;
 304         ckey = kmalloc(sizeof(*ckey), GFP_KERNEL);
 305         if (!ckey)
 306                 goto err;
 307
 308         /* TODO ceph_crypto_key_decode should really take const input */
 309         p = (void *)prep->data;
 310         ret = ceph_crypto_key_decode(ckey, &p, (char*)prep->data+datalen);
 311         if (ret < 0)
 312                 goto err_ckey;
 313
 314         prep->payload.data[0] = ckey;
 315         prep->quotalen = datalen;
 316         return 0;
 317
 318 err_ckey:
 319         kfree(ckey);
 320 err:
 321         return ret;
 322 }
 323
 324 static void ceph_key_free_preparse(struct key_preparsed_payload *prep)
 325 {
 326         struct ceph_crypto_key *ckey = prep->payload.data[0];
 327         ceph_crypto_key_destroy(ckey);
 328         kfree(ckey);
 329 }
 330
 331 static void ceph_key_destroy(struct key *key)
 332 {
 333         struct ceph_crypto_key *ckey = key->payload.data[0];
 334
 335         ceph_crypto_key_destroy(ckey);
 336         kfree(ckey);
 337 }
 338
 339 struct key_type key_type_ceph = {
 340         .name           = "ceph",
 341         .preparse       = ceph_key_preparse,
 342         .free_preparse  = ceph_key_free_preparse,
 343         .instantiate    = generic_key_instantiate,
 344         .destroy        = ceph_key_destroy,
 345 };
 346
 347 int ceph_crypto_init(void) {
 348         return register_key_type(&key_type_ceph);
 349 }
 350
 351 void ceph_crypto_shutdown(void) {
 352         unregister_key_type(&key_type_ceph);
 353 }