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         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
  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
  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
  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         *p += key->len;
 100         return ret;
 101
 102 bad:
 103         dout("failed to decode crypto key\n");
 104         return -EINVAL;
 105 }
 106
 107 int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *inkey)
 108 {
 109         int inlen = strlen(inkey);
 110         int blen = inlen * 3 / 4;
 111         void *buf, *p;
 112         int ret;
 113
 114         dout("crypto_key_unarmor %s\n", inkey);
 115         buf = kmalloc(blen, GFP_NOFS);
 116         if (!buf)
 117                 return -ENOMEM;
 118         blen = ceph_unarmor(buf, inkey, inkey+inlen);
 119         if (blen < 0) {
 120                 kfree(buf);
 121                 return blen;
 122         }
 123
 124         p = buf;
 125         ret = ceph_crypto_key_decode(key, &p, p + blen);
 126         kfree(buf);
 127         if (ret)
 128                 return ret;
 129         dout("crypto_key_unarmor key %p type %d len %d\n", key,
 130              key->type, key->len);
 131         return 0;
 132 }
 133
 134 void ceph_crypto_key_destroy(struct ceph_crypto_key *key)
 135 {
 136         if (key) {
 137                 kfree(key->key);
 138                 key->key = NULL;
 139                 if (key->tfm) {
 140                         crypto_free_sync_skcipher(key->tfm);
 141                         key->tfm = NULL;
 142                 }
 143         }
 144 }
 145
 146 static const u8 *aes_iv = (u8 *)CEPH_AES_IV;
 147
 148 /*
 149  * Should be used for buffers allocated with ceph_kvmalloc().
 150  * Currently these are encrypt out-buffer (ceph_buffer) and decrypt
 151  * in-buffer (msg front).
 152  *
 153  * Dispose of @sgt with teardown_sgtable().
 154  *
 155  * @prealloc_sg is to avoid memory allocation inside sg_alloc_table()
 156  * in cases where a single sg is sufficient.  No attempt to reduce the
 157  * number of sgs by squeezing physically contiguous pages together is
 158  * made though, for simplicity.
 159  */
 160 static int setup_sgtable(struct sg_table *sgt, struct scatterlist *prealloc_sg,
 161                          const void *buf, unsigned int buf_len)
 162 {
 163         struct scatterlist *sg;
 164         const bool is_vmalloc = is_vmalloc_addr(buf);
 165         unsigned int off = offset_in_page(buf);
 166         unsigned int chunk_cnt = 1;
 167         unsigned int chunk_len = PAGE_ALIGN(off + buf_len);
 168         int i;
 169         int ret;
 170
 171         if (buf_len == 0) {
 172                 memset(sgt, 0, sizeof(*sgt));
 173                 return -EINVAL;
 174         }
 175
 176         if (is_vmalloc) {
 177                 chunk_cnt = chunk_len >> PAGE_SHIFT;
 178                 chunk_len = PAGE_SIZE;
 179         }
 180
 181         if (chunk_cnt > 1) {
 182                 ret = sg_alloc_table(sgt, chunk_cnt, GFP_NOFS);
 183                 if (ret)
 184                         return ret;
 185         } else {
 186                 WARN_ON(chunk_cnt != 1);
 187                 sg_init_table(prealloc_sg, 1);
 188                 sgt->sgl = prealloc_sg;
 189                 sgt->nents = sgt->orig_nents = 1;
 190         }
 191
 192         for_each_sg(sgt->sgl, sg, sgt->orig_nents, i) {
 193                 struct page *page;
 194                 unsigned int len = min(chunk_len - off, buf_len);
 195
 196                 if (is_vmalloc)
 197                         page = vmalloc_to_page(buf);
 198                 else
 199                         page = virt_to_page(buf);
 200
 201                 sg_set_page(sg, page, len, off);
 202
 203                 off = 0;
 204                 buf += len;
 205                 buf_len -= len;
 206         }
 207         WARN_ON(buf_len != 0);
 208
 209         return 0;
 210 }
 211
 212 static void teardown_sgtable(struct sg_table *sgt)
 213 {
 214         if (sgt->orig_nents > 1)
 215                 sg_free_table(sgt);
 216 }
 217
 218 static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
 219                           void *buf, int buf_len, int in_len, int *pout_len)
 220 {
 221         SYNC_SKCIPHER_REQUEST_ON_STACK(req, key->tfm);
 222         struct sg_table sgt;
 223         struct scatterlist prealloc_sg;
 224         char iv[AES_BLOCK_SIZE] __aligned(8);
 225         int pad_byte = AES_BLOCK_SIZE - (in_len & (AES_BLOCK_SIZE - 1));
 226         int crypt_len = encrypt ? in_len + pad_byte : in_len;
 227         int ret;
 228
 229         WARN_ON(crypt_len > buf_len);
 230         if (encrypt)
 231                 memset(buf + in_len, pad_byte, pad_byte);
 232         ret = setup_sgtable(&sgt, &prealloc_sg, buf, crypt_len);
 233         if (ret)
 234                 return ret;
 235
 236         memcpy(iv, aes_iv, AES_BLOCK_SIZE);
 237         skcipher_request_set_sync_tfm(req, key->tfm);
 238         skcipher_request_set_callback(req, 0, NULL, NULL);
 239         skcipher_request_set_crypt(req, sgt.sgl, sgt.sgl, crypt_len, iv);
 240
 241         /*
 242         print_hex_dump(KERN_ERR, "key: ", DUMP_PREFIX_NONE, 16, 1,
 243                        key->key, key->len, 1);
 244         print_hex_dump(KERN_ERR, " in: ", DUMP_PREFIX_NONE, 16, 1,
 245                        buf, crypt_len, 1);
 246         */
 247         if (encrypt)
 248                 ret = crypto_skcipher_encrypt(req);
 249         else
 250                 ret = crypto_skcipher_decrypt(req);
 251         skcipher_request_zero(req);
 252         if (ret) {
 253                 pr_err("%s %scrypt failed: %d\n", __func__,
 254                        encrypt ? "en" : "de", ret);
 255                 goto out_sgt;
 256         }
 257         /*
 258         print_hex_dump(KERN_ERR, "out: ", DUMP_PREFIX_NONE, 16, 1,
 259                        buf, crypt_len, 1);
 260         */
 261
 262         if (encrypt) {
 263                 *pout_len = crypt_len;
 264         } else {
 265                 pad_byte = *(char *)(buf + in_len - 1);
 266                 if (pad_byte > 0 && pad_byte <= AES_BLOCK_SIZE &&
 267                     in_len >= pad_byte) {
 268                         *pout_len = in_len - pad_byte;
 269                 } else {
 270                         pr_err("%s got bad padding %d on in_len %d\n",
 271                                __func__, pad_byte, in_len);
 272                         ret = -EPERM;
 273                         goto out_sgt;
 274                 }
 275         }
 276
 277 out_sgt:
 278         teardown_sgtable(&sgt);
 279         return ret;
 280 }
 281
 282 int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
 283                void *buf, int buf_len, int in_len, int *pout_len)
 284 {
 285         switch (key->type) {
 286         case CEPH_CRYPTO_NONE:
 287                 *pout_len = in_len;
 288                 return 0;
 289         case CEPH_CRYPTO_AES:
 290                 return ceph_aes_crypt(key, encrypt, buf, buf_len, in_len,
 291                                       pout_len);
 292         default:
 293                 return -ENOTSUPP;
 294         }
 295 }
 296
 297 static int ceph_key_preparse(struct key_preparsed_payload *prep)
 298 {
 299         struct ceph_crypto_key *ckey;
 300         size_t datalen = prep->datalen;
 301         int ret;
 302         void *p;
 303
 304         ret = -EINVAL;
 305         if (datalen <= 0 || datalen > 32767 || !prep->data)
 306                 goto err;
 307
 308         ret = -ENOMEM;
 309         ckey = kmalloc(sizeof(*ckey), GFP_KERNEL);
 310         if (!ckey)
 311                 goto err;
 312
 313         /* TODO ceph_crypto_key_decode should really take const input */
 314         p = (void *)prep->data;
 315         ret = ceph_crypto_key_decode(ckey, &p, (char*)prep->data+datalen);
 316         if (ret < 0)
 317                 goto err_ckey;
 318
 319         prep->payload.data[0] = ckey;
 320         prep->quotalen = datalen;
 321         return 0;
 322
 323 err_ckey:
 324         kfree(ckey);
 325 err:
 326         return ret;
 327 }
 328
 329 static void ceph_key_free_preparse(struct key_preparsed_payload *prep)
 330 {
 331         struct ceph_crypto_key *ckey = prep->payload.data[0];
 332         ceph_crypto_key_destroy(ckey);
 333         kfree(ckey);
 334 }
 335
 336 static void ceph_key_destroy(struct key *key)
 337 {
 338         struct ceph_crypto_key *ckey = key->payload.data[0];
 339
 340         ceph_crypto_key_destroy(ckey);
 341         kfree(ckey);
 342 }
 343
 344 struct key_type key_type_ceph = {
 345         .name           = "ceph",
 346         .preparse       = ceph_key_preparse,
 347         .free_preparse  = ceph_key_free_preparse,
 348         .instantiate    = generic_key_instantiate,
 349         .destroy        = ceph_key_destroy,
 350 };
 351
 352 int __init ceph_crypto_init(void)
 353 {
 354         return register_key_type(&key_type_ceph);
 355 }
 356
 357 void ceph_crypto_shutdown(void)
 358 {
 359         unregister_key_type(&key_type_ceph);
 360 }