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 #ifdef USE_PLUGINS
  12 static void init_plugins(void)
  13 {
  14 }
  15 #else /* USE_PLUGINS */
  16 #       define init_plugins()   do { } while(0)
  17 #endif /* USE_PLUGINS */
  18
  19 static struct hash_backend *hash_backends[] = {
  20 #ifdef BUILTIN_GCRYPT
  21         &hash_gcrypt_backend,
  22 #endif
  23         NULL
  24 };
  25
  26 struct hash_backend *get_hash_backend(const char *name)
  27 {
  28         struct hash_backend **backend;
  29
  30         init_plugins();
  31
  32         for(backend = hash_backends; *backend; backend++)
  33                 if (!name || strcmp(name, (*backend)->name) == 0)
  34                         break;
  35
  36         return *backend;
  37 }
  38
  39 void put_hash_backend(struct hash_backend *backend)
  40 {
  41 }
  42
  43 int hash(const char *backend_name, const char *hash_name,
  44          char *result, size_t size,
  45          const char *passphrase, size_t sizep)
  46 {
  47         struct hash_backend *backend;
  48         struct hash_type *hashes = NULL, *hash;
  49         char hash_name_buf[256], *s;
  50         size_t pad = 0;
  51         int r = -ENOENT;
  52
  53         if (strlen(hash_name) >= sizeof(hash_name_buf)) {
  54                 set_error("hash name too long: %s", hash_name);
  55                 return -ENAMETOOLONG;
  56         }
  57
  58         if ((s = strchr(hash_name, ':'))) {
  59                 size_t hlen;
  60                 strcpy(hash_name_buf, hash_name);
  61                 hash_name_buf[s-hash_name] = '\0';
  62                 hash_name = hash_name_buf;
  63                 hlen = atoi(++s);
  64                 if (hlen > size) {
  65                         set_error("requested hash length (%zd) > key length (%zd)", hlen, size);
  66                         return -EINVAL;
  67                 }
  68                 pad = size-hlen;
  69                 size = hlen;
  70         }
  71
  72         backend = get_hash_backend(backend_name);
  73         if (!backend) {
  74                 set_error("No hash backend found");
  75                 return -ENOSYS;
  76         }
  77
  78         hashes = backend->get_hashes();
  79         if (!hashes) {
  80                 set_error("No hash functions available");
  81                 goto out;
  82         }
  83
  84         for(hash = hashes; hash->name; hash++)
  85                 if (strcmp(hash->name, hash_name) == 0)
  86                         break;
  87         if (!hash->name) {
  88                 set_error("Unknown hash type %s", hash_name);
  89                 goto out;
  90         }
  91
  92         r = hash->fn(hash->private, size, result, sizep, passphrase);
  93         if (r < 0) {
  94                 set_error("Error hashing passphrase");
  95                 goto out;
  96         }
  97
  98         if (pad) {
  99                 memset(result+size, 0, pad);
 100         }
 101
 102 out:
 103         if (hashes)
 104                 backend->free_hashes(hashes);
 105         put_hash_backend(backend);
 106
 107         return r;
 108 }