lib/backends.c

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include <stdlib.h>
   4 #include <errno.h>
   5
   6 #include "libcryptsetup.h"
   7 #include "internal.h"
   8
   9 extern struct hash_backend hash_gcrypt_backend;
  10
  11 static struct hash_backend *hash_backends[] = {
  12         &hash_gcrypt_backend,
  13         NULL
  14 };
  15
  16 struct hash_backend *get_hash_backend(const char *name)
  17 {
  18         struct hash_backend **backend;
  19
  20         for(backend = hash_backends; *backend; backend++)
  21                 if (!name || strcmp(name, (*backend)->name) == 0)
  22                         break;
  23
  24         return *backend;
  25 }
  26
  27 void put_hash_backend(struct hash_backend *backend)
  28 {
  29 }
  30
  31 int hash(const char *backend_name, const char *hash_name,
  32          char *result, size_t size,
  33          const char *passphrase, size_t sizep)
  34 {
  35         struct hash_backend *backend;
  36         struct hash_type *hashes = NULL, *hash;
  37         char hash_name_buf[256], *s;
  38         size_t pad = 0;
  39         int r = -ENOENT;
  40
  41         if (strlen(hash_name) >= sizeof(hash_name_buf)) {
  42                 set_error("hash name too long: %s", hash_name);
  43                 return -ENAMETOOLONG;
  44         }
  45
  46         if ((s = strchr(hash_name, ':'))) {
  47                 size_t hlen;
  48                 strcpy(hash_name_buf, hash_name);
  49                 hash_name_buf[s-hash_name] = '\0';
  50                 hash_name = hash_name_buf;
  51                 hlen = atoi(++s);
  52                 if (hlen > size) {
  53                         set_error("requested hash length (%zd) > key length (%zd)", hlen, size);
  54                         return -EINVAL;
  55                 }
  56                 pad = size-hlen;
  57                 size = hlen;
  58         }
  59
  60         backend = get_hash_backend(backend_name);
  61         if (!backend) {
  62                 set_error("No hash backend found");
  63                 return -ENOSYS;
  64         }
  65
  66         hashes = backend->get_hashes();
  67         if (!hashes) {
  68                 set_error("No hash functions available");
  69                 goto out;
  70         }
  71
  72         for(hash = hashes; hash->name; hash++)
  73                 if (strcmp(hash->name, hash_name) == 0)
  74                         break;
  75         if (!hash->name) {
  76                 set_error("Unknown hash type %s", hash_name);
  77                 goto out;
  78         }
  79
  80         r = hash->fn(hash->private, size, result, sizep, passphrase);
  81         if (r < 0) {
  82                 set_error("Error hashing passphrase");
  83                 goto out;
  84         }
  85
  86         if (pad) {
  87                 memset(result+size, 0, pad);
  88         }
  89
  90 out:
  91         if (hashes)
  92                 backend->free_hashes(hashes);
  93         put_hash_backend(backend);
  94
  95         return r;
  96 }