openssl: Add support for RFC4716 keys

[paraslash.git] / crypt_common.c

diff --git a/crypt_common.c b/crypt_common.c
index 277897f2b47a3c9587d4bb08a5b634b7d4c53f46..c1e40d920ff425ccfdcc536c5fb69cd0422472ca 100644 (file)
--- a/crypt_common.c
+++ b/crypt_common.c
@@ -230,3 +230,90 @@ int find_openssh_bignum_offset(const unsigned char *data, int len)
        return p - data;
 }
 
        return p - data;
 }
 

+/** Private PEM keys (legacy format) start with this header. */
+#define PRIVATE_PEM_KEY_HEADER "-----BEGIN RSA PRIVATE KEY-----"
+/** Private OPENSSH keys (RFC4716) start with this header. */
+#define PRIVATE_OPENSSH_KEY_HEADER "-----BEGIN OPENSSH PRIVATE KEY-----"
+/** Private PEM keys (legacy format) end with this footer. */
+#define PRIVATE_PEM_KEY_FOOTER "-----END RSA PRIVATE KEY-----"
+/** Private OPENSSH keys (RFC4716) end with this footer. */
+#define PRIVATE_OPENSSH_KEY_FOOTER "-----END OPENSSH PRIVATE KEY-----"
+
+/**
+ * Decode an openssh-v1 (aka RFC4716) or PEM (aka ASN.1) private key.
+ *
+ * \param key_file The private key file (usually id_rsa).
+ * \param result Pointer to base64-decoded blob is returned here.
+ * \param blob_size The size of the decoded blob.
+ *
+ * This only checks header and footer and base64-decodes the part in between.
+ * No attempt to read the decoded part is made.
+ *
+ * \return Negative on errors, PKT_PEM or PKT_OPENSSH on success, indicating
+ * the type of key.
+ */
+int decode_private_key(const char *key_file, unsigned char **result,
+               size_t *blob_size)
+{
+       int ret, ret2, i, j, key_type;
+       void *map;
+       size_t map_size, key_size;
+       unsigned char *blob = NULL;
+       char *begin, *footer, *key;
+
+       ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
+       if (ret < 0)
+               goto out;
+       ret = -E_KEY_MARKER;
+       if (strncmp(map, PRIVATE_PEM_KEY_HEADER,
+                       strlen(PRIVATE_PEM_KEY_HEADER)) == 0) {
+               key_type = PKT_PEM;
+               begin = map + strlen(PRIVATE_PEM_KEY_HEADER);
+               footer = strstr(map, PRIVATE_PEM_KEY_FOOTER);
+               PARA_INFO_LOG("detected legacy PEM key %s\n", key_file);
+       } else if (strncmp(map, PRIVATE_OPENSSH_KEY_HEADER,
+                       strlen(PRIVATE_OPENSSH_KEY_HEADER)) == 0) {
+               key_type = PKT_OPENSSH;
+               begin = map + strlen(PRIVATE_OPENSSH_KEY_HEADER);
+               footer = strstr(map, PRIVATE_OPENSSH_KEY_FOOTER);
+               PARA_INFO_LOG("detected openssh key %s\n", key_file);
+       } else
+               goto unmap;
+       if (!footer)
+               goto unmap;
+       /* skip whitespace at the beginning */
+       for (; begin < footer; begin++) {
+               if (para_isspace(*begin))
+                       continue;
+               break;
+       }
+       ret = -E_KEY_MARKER;
+       if (begin >= footer)
+               goto unmap;
+
+       key_size = footer - begin;
+       key = para_malloc(key_size + 1);
+       for (i = 0, j = 0; begin + i < footer; i++) {
+               if (para_isspace(begin[i]))
+                       continue;
+               key[j++] = begin[i];
+       }
+       key[j] = '\0';
+       ret = base64_decode(key, j, (char **)&blob, blob_size);
+       free(key);
+       if (ret < 0)
+               goto unmap;
+       ret = key_type;
+unmap:
+       ret2 = para_munmap(map, map_size);
+       if (ret >= 0 && ret2 < 0)
+               ret = ret2;
+       if (ret < 0) {
+               free(blob);
+               blob = NULL;
+       }
+out:
+       *result = blob;
+       return ret;
+}
+