1 files changed, 133 insertions, 28 deletions

diff --git a/Utilities/cmcurl/lib/vssh/libssh2.c b/Utilities/cmcurl/lib/vssh/libssh2.c
index a772f1f..d269263 100644
--- a/Utilities/cmcurl/lib/vssh/libssh2.c
+++ b/Utilities/cmcurl/lib/vssh/libssh2.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2022, 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
@@ -81,6 +81,11 @@
 #include "select.h"
 #include "warnless.h"
 #include "curl_path.h"
+#include "strcase.h"
+
+#include <curl_base64.h> /* for base64 encoding/decoding */
+#include <curl_sha256.h>
+
 
 /* The last 3 #include files should be in this order */
 #include "curl_printf.h"
@@ -428,7 +433,9 @@ static int sshkeycallback(struct Curl_easy *easy,
  * libssh2 1.2.8 fixed the problem with 32bit ints used for sockets on win64.
  */
 #ifdef HAVE_LIBSSH2_SESSION_HANDSHAKE
-#define libssh2_session_startup(x,y) libssh2_session_handshake(x,y)
+#define session_startup(x,y) libssh2_session_handshake(x, y)
+#else
+#define session_startup(x,y) libssh2_session_startup(x, (int)y)
 #endif
 
 static CURLcode ssh_knownhost(struct Curl_easy *data)
@@ -490,7 +497,7 @@ static CURLcode ssh_knownhost(struct Curl_easy *data)
         break;
 #endif
       default:
-        infof(data, "unsupported key type, can't check knownhosts!");
+        infof(data, "unsupported key type, can't check knownhosts");
         keybit = 0;
         break;
       }
@@ -585,7 +592,7 @@ static CURLcode ssh_knownhost(struct Curl_easy *data)
                                           LIBSSH2_KNOWNHOST_KEYENC_RAW|
                                           keybit, NULL);
         if(addrc)
-          infof(data, "Warning adding the known host %s failed!",
+          infof(data, "WARNING: adding the known host %s failed",
                 conn->host.name);
         else if(rc == CURLKHSTAT_FINE_ADD_TO_FILE ||
                 rc == CURLKHSTAT_FINE_REPLACE) {
@@ -596,7 +603,7 @@ static CURLcode ssh_knownhost(struct Curl_easy *data)
                                         data->set.str[STRING_SSH_KNOWNHOSTS],
                                         LIBSSH2_KNOWNHOST_FILE_OPENSSH);
           if(wrc) {
-            infof(data, "Warning, writing %s failed!",
+            infof(data, "WARNING: writing %s failed",
                   data->set.str[STRING_SSH_KNOWNHOSTS]);
           }
         }
@@ -615,40 +622,138 @@ static CURLcode ssh_check_fingerprint(struct Curl_easy *data)
   struct connectdata *conn = data->conn;
   struct ssh_conn *sshc = &conn->proto.sshc;
   const char *pubkey_md5 = data->set.str[STRING_SSH_HOST_PUBLIC_KEY_MD5];
-  char md5buffer[33];
+  const char *pubkey_sha256 = data->set.str[STRING_SSH_HOST_PUBLIC_KEY_SHA256];
 
-  const char *fingerprint = libssh2_hostkey_hash(sshc->ssh_session,
-      LIBSSH2_HOSTKEY_HASH_MD5);
+  infof(data, "SSH MD5 public key: %s",
+    pubkey_md5 != NULL ? pubkey_md5 : "NULL");
+  infof(data, "SSH SHA256 public key: %s",
+      pubkey_sha256 != NULL ? pubkey_sha256 : "NULL");
 
-  if(fingerprint) {
+  if(pubkey_sha256) {
+    const char *fingerprint = NULL;
+    char *fingerprint_b64 = NULL;
+    size_t fingerprint_b64_len;
+    size_t pub_pos = 0;
+    size_t b64_pos = 0;
+
+#ifdef LIBSSH2_HOSTKEY_HASH_SHA256
     /* The fingerprint points to static storage (!), don't free() it. */
-    int i;
-    for(i = 0; i < 16; i++)
-      msnprintf(&md5buffer[i*2], 3, "%02x", (unsigned char) fingerprint[i]);
-    infof(data, "SSH MD5 fingerprint: %s", md5buffer);
+    fingerprint = libssh2_hostkey_hash(sshc->ssh_session,
+        LIBSSH2_HOSTKEY_HASH_SHA256);
+#else
+    const char *hostkey;
+    size_t len = 0;
+    unsigned char hash[32];
+
+    hostkey = libssh2_session_hostkey(sshc->ssh_session, &len, NULL);
+    if(hostkey) {
+      if(!Curl_sha256it(hash, (const unsigned char *) hostkey, len))
+        fingerprint = (char *) hash;
+    }
+#endif
+
+    if(!fingerprint) {
+      failf(data,
+          "Denied establishing ssh session: sha256 fingerprint "
+          "not available");
+      state(data, SSH_SESSION_FREE);
+      sshc->actualcode = CURLE_PEER_FAILED_VERIFICATION;
+      return sshc->actualcode;
+    }
+
+    /* The length of fingerprint is 32 bytes for SHA256.
+     * See libssh2_hostkey_hash documentation. */
+    if(Curl_base64_encode(fingerprint, 32, &fingerprint_b64,
+                          &fingerprint_b64_len) != CURLE_OK) {
+      state(data, SSH_SESSION_FREE);
+      sshc->actualcode = CURLE_PEER_FAILED_VERIFICATION;
+      return sshc->actualcode;
+    }
+
+    if(!fingerprint_b64) {
+      failf(data, "sha256 fingerprint could not be encoded");
+      state(data, SSH_SESSION_FREE);
+      sshc->actualcode = CURLE_PEER_FAILED_VERIFICATION;
+      return sshc->actualcode;
+    }
+
+    infof(data, "SSH SHA256 fingerprint: %s", fingerprint_b64);
+
+    /* Find the position of any = padding characters in the public key */
+    while((pubkey_sha256[pub_pos] != '=') && pubkey_sha256[pub_pos]) {
+      pub_pos++;
+    }
+
+    /* Find the position of any = padding characters in the base64 coded
+     * hostkey fingerprint */
+    while((fingerprint_b64[b64_pos] != '=') && fingerprint_b64[b64_pos]) {
+      b64_pos++;
+    }
+
+    /* Before we authenticate we check the hostkey's sha256 fingerprint
+     * against a known fingerprint, if available.
+     */
+    if((pub_pos != b64_pos) ||
+       strncmp(fingerprint_b64, pubkey_sha256, pub_pos)) {
+      free(fingerprint_b64);
+
+      failf(data,
+            "Denied establishing ssh session: mismatch sha256 fingerprint. "
+            "Remote %s is not equal to %s", fingerprint_b64, pubkey_sha256);
+      state(data, SSH_SESSION_FREE);
+      sshc->actualcode = CURLE_PEER_FAILED_VERIFICATION;
+      return sshc->actualcode;
+    }
+
+    free(fingerprint_b64);
+
+    infof(data, "SHA256 checksum match");
   }
 
-  /* Before we authenticate we check the hostkey's MD5 fingerprint
-   * against a known fingerprint, if available.
-   */
-  if(pubkey_md5 && strlen(pubkey_md5) == 32) {
+  if(pubkey_md5) {
+    char md5buffer[33];
+    const char *fingerprint = NULL;
+
+    fingerprint = libssh2_hostkey_hash(sshc->ssh_session,
+        LIBSSH2_HOSTKEY_HASH_MD5);
+
+    if(fingerprint) {
+      /* The fingerprint points to static storage (!), don't free() it. */
+      int i;
+      for(i = 0; i < 16; i++) {
+        msnprintf(&md5buffer[i*2], 3, "%02x", (unsigned char) fingerprint[i]);
+      }
+
+      infof(data, "SSH MD5 fingerprint: %s", md5buffer);
+    }
+
+    /* This does NOT verify the length of 'pubkey_md5' separately, which will
+       make the comparison below fail unless it is exactly 32 characters */
     if(!fingerprint || !strcasecompare(md5buffer, pubkey_md5)) {
-      if(fingerprint)
+      if(fingerprint) {
         failf(data,
-            "Denied establishing ssh session: mismatch md5 fingerprint. "
-            "Remote %s is not equal to %s", md5buffer, pubkey_md5);
-      else
+              "Denied establishing ssh session: mismatch md5 fingerprint. "
+              "Remote %s is not equal to %s", md5buffer, pubkey_md5);
+      }
+      else {
         failf(data,
-            "Denied establishing ssh session: md5 fingerprint not available");
+              "Denied establishing ssh session: md5 fingerprint "
+              "not available");
+      }
       state(data, SSH_SESSION_FREE);
       sshc->actualcode = CURLE_PEER_FAILED_VERIFICATION;
       return sshc->actualcode;
     }
-    infof(data, "MD5 checksum match!");
+    infof(data, "MD5 checksum match");
+  }
+
+  if(!pubkey_md5 && !pubkey_sha256) {
+    return ssh_knownhost(data);
+  }
+  else {
     /* as we already matched, we skip the check for known hosts */
     return CURLE_OK;
   }
-  return ssh_knownhost(data);
 }
 
 /*
@@ -826,7 +931,7 @@ static CURLcode ssh_statemach_act(struct Curl_easy *data, bool *block)
       /* FALLTHROUGH */
 
     case SSH_S_STARTUP:
-      rc = libssh2_session_startup(sshc->ssh_session, (int)sock);
+      rc = session_startup(sshc->ssh_session, sock);
       if(rc == LIBSSH2_ERROR_EAGAIN) {
         break;
       }
@@ -1362,7 +1467,7 @@ static CURLcode ssh_statemach_act(struct Curl_easy *data, bool *block)
          */
         cp = strchr(cmd, ' ');
         if(!cp) {
-          failf(data, "Syntax error command '%s'. Missing parameter!",
+          failf(data, "Syntax error command '%s', missing parameter",
                 cmd);
           state(data, SSH_SFTP_CLOSE);
           sshc->nextstate = SSH_NO_STATE;
@@ -3121,7 +3226,7 @@ static CURLcode ssh_connect(struct Curl_easy *data, bool *done)
     sshrecv.recvptr = ssh_tls_recv;
     sshsend.sendptr = ssh_tls_send;
 
-    infof(data, "Uses HTTPS proxy!");
+    infof(data, "Uses HTTPS proxy");
     /*
       Setup libssh2 callbacks to make it read/write TLS from the socket.
 
@@ -3610,7 +3715,7 @@ void Curl_ssh_cleanup(void)
 
 void Curl_ssh_version(char *buffer, size_t buflen)
 {
-  (void)msnprintf(buffer, buflen, "libssh2/%s", LIBSSH2_VERSION);
+  (void)msnprintf(buffer, buflen, "libssh2/%s", CURL_LIBSSH2_VERSION);
 }
 
 /* The SSH session is associated with the *CONNECTION* but the callback user