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