http: introduce AWS HTTP v4 Signature

It is a security process for HTTP.

It doesn't seems to be standard, but it is used by some cloud providers.

Aws:
https://docs.aws.amazon.com/general/latest/gr/signature-version-4.html
Outscale:
https://wiki.outscale.net/display/EN/Creating+a+Canonical+Request
GCP (I didn't test that this code work with GCP though):
https://cloud.google.com/storage/docs/access-control/signing-urls-manually

most of the code is in lib/http_v4_signature.c

Information require by the algorithm:
- The URL
- Current time
-  some prefix that are append to some of the signature parameters.

The data extracted from the URL are: the URI, the region,
the host and the API type

example:
https://api.eu-west-2.outscale.com/api/latest/ReadNets
        ~~~ ~~~~~~~~               ~~~~~~~~~~~~~~~~~~~
        ^       ^                          ^
       /         \                        URI
   API type     region

Small description of the algorithm:
- make canonical header using content type, the host, and the date
- hash the post data
- make canonical_request using custom request, the URI,
  the get data, the canonical header, the signed header
  and post data hash
- hash canonical_request
- make str_to_sign using one of the prefix pass in parameter,
  the date, the credential scope and the canonical_request hash
- compute hmac from date, using secret key as key.
- compute hmac from region, using above hmac as key
- compute hmac from api_type, using above hmac as key
- compute hmac from request_type, using above hmac as key
- compute hmac from str_to_sign using above hmac as key
- create Authorization header using above hmac, prefix pass in parameter,
  the date, and above hash

Signed-off-by: Matthias Gatto <matthias.gatto@outscale.com>

Closes #5703

1 files changed, 333 insertions, 0 deletions

diff --git a/lib/http_aws_sigv4.c b/lib/http_aws_sigv4.c
new file mode 100644
index 000000000..a3aa72cdf
--- /dev/null
+++ b/lib/http_aws_sigv4.c
@@ -0,0 +1,333 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#if !defined(CURL_DISABLE_HTTP) && !defined(CURL_DISABLE_CRYPTO_AUTH)
+
+#include "urldata.h"
+#include "strcase.h"
+#include "vauth/vauth.h"
+#include "vauth/digest.h"
+#include "http_aws_sigv4.h"
+#include "curl_sha256.h"
+#include "transfer.h"
+
+#include "strcase.h"
+#include "parsedate.h"
+#include "sendf.h"
+
+#include <time.h>
+
+/* The last 3 #include files should be in this order */
+#include "curl_printf.h"
+#include "curl_memory.h"
+#include "memdebug.h"
+
+#define HMAC_SHA256(k, kl, d, dl, o)                                    \
+  if(Curl_hmacit(Curl_HMAC_SHA256, (unsigned char *)k,                  \
+                 (unsigned int)kl,                                      \
+                 (unsigned char *)d,                                    \
+                 (unsigned int)dl, o) != CURLE_OK) {                    \
+    ret = CURLE_OUT_OF_MEMORY;                                          \
+    goto free_all;                                                      \
+  }
+
+#define PROVIDER_MAX_L 16
+#define REQUEST_TYPE_L (PROVIDER_MAX_L + sizeof("4_request"))
+/* secret key is 40 bytes long + PROVIDER_MAX_L + \0 */
+#define FULL_SK_L (PROVIDER_MAX_L + 40 + 1)
+
+static void sha256_to_hex(char *dst, unsigned char *sha, size_t dst_l)
+{
+  int i;
+
+  DEBUGASSERT(dst_l >= 65);
+  for(i = 0; i < 32; ++i) {
+    curl_msnprintf(dst + (i * 2), dst_l - (i * 2), "%02x", sha[i]);
+  }
+}
+
+CURLcode Curl_output_aws_sigv4(struct connectdata *conn, bool proxy)
+{
+  CURLcode ret = CURLE_OK;
+  char sk[FULL_SK_L] = {0};
+  struct Curl_easy *data = conn->data;
+  const char *customrequest = data->set.str[STRING_CUSTOMREQUEST];
+  const char *hostname = data->state.up.hostname;
+  struct tm info;
+  time_t rawtime;
+  /* aws is the default because some provider that are not amazone still use
+   * aws:amz as prefix
+   */
+  const char *provider = data->set.str[STRING_AWS_SIGV4] ?
+    data->set.str[STRING_AWS_SIGV4] : "aws:amz";
+  size_t provider_l = strlen(provider);
+  char low_provider0[PROVIDER_MAX_L + 1] = {0};
+  char low_provider[PROVIDER_MAX_L + 1] = {0};
+  char up_provider[PROVIDER_MAX_L + 1] = {0};
+  char mid_provider[PROVIDER_MAX_L + 1] = {0};
+  char *region = NULL;
+  char *uri = NULL;
+  char *api_type = NULL;
+  char date_iso[17];
+  char date[9];
+  char date_str[64];
+  const char *post_data = data->set.postfields ?
+    data->set.postfields : "";
+  const char *content_type = Curl_checkheaders(conn, "Content-Type");
+  unsigned char sha_d[32];
+  char sha_hex[65];
+  char *cred_scope = NULL;
+  char *signed_headers = NULL;
+  char request_type[REQUEST_TYPE_L];
+  char *canonical_hdr = NULL;
+  char *canonical_request = NULL;
+  char *str_to_sign = NULL;
+  unsigned char tmp_sign0[32] = {0};
+  unsigned char tmp_sign1[32] = {0};
+  char *auth = NULL;
+  char *tmp;
+  #ifdef DEBUGBUILD
+  char *force_timestamp;
+  #endif
+
+  DEBUGASSERT(!proxy);
+  (void)proxy;
+
+  if(Curl_checkheaders(conn, "Authorization")) {
+    /* Authorization already present, Bailing out */
+    return CURLE_OK;
+  }
+
+  if(content_type) {
+    content_type = strchr(content_type, ':');
+    if(!content_type)
+      return CURLE_FAILED_INIT;
+    content_type++;
+    /* Skip whitespace now */
+    while(*content_type == ' ' || *content_type == '\t')
+      ++content_type;
+  }
+
+  /* Get Parameter
+     Google and Outscale use the same OSC or GOOG,
+     but Amazon use AWS and AMZ for header arguments */
+  tmp = strchr(provider, ':');
+  if(tmp) {
+    provider_l = tmp - provider;
+    if(provider_l >= PROVIDER_MAX_L) {
+      infof(data, "v4 signature argument string too long\n");
+      return CURLE_BAD_FUNCTION_ARGUMENT;
+    }
+    Curl_strntolower(low_provider0, provider, provider_l);
+    Curl_strntoupper(up_provider, provider, provider_l);
+    provider = tmp + 1;
+    /* if "xxx:" was pass as parameter, tmp + 1 should point to \0 */
+    provider_l = strlen(provider);
+    if(provider_l >= PROVIDER_MAX_L) {
+      infof(data, "v4 signature argument string too long\n");
+      return CURLE_BAD_FUNCTION_ARGUMENT;
+    }
+    Curl_strntolower(low_provider, provider, provider_l);
+    Curl_strntolower(mid_provider, provider, provider_l);
+  }
+  else if(provider_l <= PROVIDER_MAX_L) {
+    Curl_strntolower(low_provider0, provider, provider_l);
+    Curl_strntolower(low_provider, provider, provider_l);
+    Curl_strntolower(mid_provider, provider, provider_l);
+    Curl_strntoupper(up_provider, provider, provider_l);
+    mid_provider[0] = Curl_raw_toupper(mid_provider[0]);
+  }
+  else {
+    infof(data, "v4 signature argument string too long\n");
+    return CURLE_BAD_FUNCTION_ARGUMENT;
+  }
+
+#ifdef DEBUGBUILD
+  force_timestamp = getenv("CURL_FORCETIME");
+  if(force_timestamp)
+    rawtime = 0;
+  else
+#endif
+    time(&rawtime);
+
+  ret = Curl_gmtime(rawtime, &info);
+  if(ret != CURLE_OK) {
+    return ret;
+  }
+
+  if(!strftime(date_iso, sizeof(date_iso), "%Y%m%dT%H%M%SZ", &info)) {
+    return CURLE_OUT_OF_MEMORY;
+  }
+
+  memcpy(date, date_iso, sizeof(date));
+  date[sizeof(date) - 1] = 0;
+  api_type = strdup(hostname);
+  if(!api_type) {
+    ret = CURLE_OUT_OF_MEMORY;
+    goto free_all;
+  }
+
+  tmp = strchr(api_type, '.');
+  if(!tmp) {
+    ret = CURLE_URL_MALFORMAT;
+    goto free_all;
+  }
+  *tmp = 0;
+
+  /* at worst, *(tmp + 1) is a '\0' */
+  region = tmp + 1;
+
+  tmp = strchr(region, '.');
+  if(!tmp) {
+    ret = CURLE_URL_MALFORMAT;
+    goto free_all;
+  }
+  *tmp = 0;
+
+  uri = data->state.up.path;
+
+  if(!curl_msnprintf(request_type, REQUEST_TYPE_L, "%s4_request",
+                     low_provider0)) {
+    ret = CURLE_OUT_OF_MEMORY;
+    goto free_all;
+  }
+
+  cred_scope = curl_maprintf("%s/%s/%s/%s", date, region, api_type,
+                             request_type);
+  if(!cred_scope) {
+    ret = CURLE_OUT_OF_MEMORY;
+    goto free_all;
+  }
+
+  if(content_type) {
+    canonical_hdr = curl_maprintf(
+      "content-type:%s\n"
+      "host:%s\n"
+      "x-%s-date:%s\n", content_type, hostname, low_provider, date_iso);
+    signed_headers = curl_maprintf("content-type;host;x-%s-date",
+                                   low_provider);
+  }
+  else if(data->state.up.query) {
+    canonical_hdr = curl_maprintf(
+      "host:%s\n"
+      "x-%s-date:%s\n", hostname, low_provider, date_iso);
+    signed_headers = curl_maprintf("host;x-%s-date", low_provider);
+  }
+  else {
+    ret = CURLE_FAILED_INIT;
+    goto free_all;
+  }
+
+  if(!canonical_hdr || !signed_headers) {
+    ret = CURLE_OUT_OF_MEMORY;
+    goto free_all;
+  }
+
+  Curl_sha256it(sha_d, (const unsigned char *)post_data, strlen(post_data));
+  sha256_to_hex(sha_hex, sha_d, sizeof(sha_hex));
+
+  canonical_request = curl_maprintf(
+    "%s\n" /* Method */
+    "%s\n" /* uri */
+    "%s\n" /* querystring */
+    "%s\n" /* canonical_headers */
+    "%s\n" /* signed header */
+    "%s" /* SHA ! */,
+    customrequest, uri,
+    data->state.up.query ? data->state.up.query : "",
+    canonical_hdr, signed_headers, sha_hex);
+  if(!canonical_request) {
+    ret = CURLE_OUT_OF_MEMORY;
+    goto free_all;
+  }
+
+  Curl_sha256it(sha_d, (unsigned char *)canonical_request,
+                strlen(canonical_request));
+  sha256_to_hex(sha_hex, sha_d, sizeof(sha_hex));
+
+  /* Google allow to use rsa key instead of HMAC, so this code might change
+   * In the furure, but for now we support only HMAC version
+   */
+  str_to_sign = curl_maprintf("%s4-HMAC-SHA256\n"
+                              "%s\n%s\n%s",
+                              up_provider, date_iso, cred_scope, sha_hex);
+  if(!str_to_sign) {
+    ret = CURLE_OUT_OF_MEMORY;
+    goto free_all;
+  }
+
+  curl_msnprintf(sk, sizeof(sk) - 1, "%s4%s", up_provider,
+                 data->set.str[STRING_PASSWORD]);
+
+  HMAC_SHA256(sk, strlen(sk), date,
+              strlen(date), tmp_sign0);
+  sha256_to_hex(sha_hex, tmp_sign0, sizeof(sha_hex));
+
+  HMAC_SHA256(tmp_sign0, sizeof(tmp_sign0), region,
+              strlen(region), tmp_sign1);
+  HMAC_SHA256(tmp_sign1, sizeof(tmp_sign1), api_type,
+              strlen(api_type), tmp_sign0);
+  HMAC_SHA256(tmp_sign0, sizeof(tmp_sign0), request_type,
+              strlen(request_type),
+              tmp_sign1);
+  HMAC_SHA256(tmp_sign1, sizeof(tmp_sign1), str_to_sign,
+              strlen(str_to_sign), tmp_sign0);
+
+  sha256_to_hex(sha_hex, tmp_sign0, sizeof(sha_hex));
+
+  auth = curl_maprintf("Authorization: %s4-HMAC-SHA256 Credential=%s/%s, "
+                       "SignedHeaders=%s, Signature=%s",
+                       up_provider, data->set.str[STRING_USERNAME], cred_scope,
+                       signed_headers, sha_hex);
+  if(!auth) {
+    ret = CURLE_OUT_OF_MEMORY;
+    goto free_all;
+  }
+
+  curl_msnprintf(date_str, sizeof(date_str), "X-%s-Date: %s",
+                 mid_provider, date_iso);
+  data->set.headers = curl_slist_append(data->set.headers, date_str);
+  if(!data->set.headers) {
+    ret = CURLE_FAILED_INIT;
+    goto free_all;
+  }
+  data->set.headers = curl_slist_append(data->set.headers, auth);
+  if(!data->set.headers) {
+    ret = CURLE_FAILED_INIT;
+    goto free_all;
+  }
+  data->state.authhost.done = 1;
+
+free_all:
+  free(canonical_request);
+  free(signed_headers);
+  free(str_to_sign);
+  free(canonical_hdr);
+  free(auth);
+  free(cred_scope);
+  free(api_type);
+  return ret;
+}
+
+#endif /* !defined(CURL_DISABLE_HTTP) && !defined(CURL_DISABLE_CRYPTO_AUTH) */