From be17dc9d31e805c03372b690dde67838b3bfc12d Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Wed, 24 May 2023 16:34:11 +0200
Subject: [PATCH] libssh: when keyboard-interactive auth fails, try password
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The state machine had a mistake in that it would not carry on to that
next step.

This also adds a verbose output what methods that are available from the
server and renames the macros that change to the next auth methods to
try.

Reported-by: 左潇峰
Fixes #11196
Closes #11197
---
 lib/ssh-libssh.c | 43 +++++++++++++++++++++++++++----------------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/lib/ssh-libssh.c b/lib/ssh-libssh.c
index 7ebe61321419f..1cecb649cb623 100644
--- a/lib/ssh-libssh.c
+++ b/lib/ssh-libssh.c
@@ -442,7 +442,7 @@ static int myssh_is_known(struct Curl_easy *data)
   break; \
 }
 
-#define MOVE_TO_LAST_AUTH \
+#define MOVE_TO_PASSWD_AUTH \
   if(sshc->auth_methods & SSH_AUTH_METHOD_PASSWORD) { \
     rc = SSH_OK; \
     state(conn, SSH_AUTH_PASS_INIT); \
@@ -452,25 +452,25 @@ static int myssh_is_known(struct Curl_easy *data)
     MOVE_TO_ERROR_STATE(CURLE_LOGIN_DENIED); \
   }
 
-#define MOVE_TO_TERTIARY_AUTH \
+#define MOVE_TO_KEY_AUTH \
   if(sshc->auth_methods & SSH_AUTH_METHOD_INTERACTIVE) { \
     rc = SSH_OK; \
     state(conn, SSH_AUTH_KEY_INIT); \
     break; \
   } \
   else { \
-    MOVE_TO_LAST_AUTH; \
+    MOVE_TO_PASSWD_AUTH; \
   }
 
-#define MOVE_TO_SECONDARY_AUTH \
+#define MOVE_TO_GSSAPI_AUTH \
   if(sshc->auth_methods & SSH_AUTH_METHOD_GSSAPI_MIC) { \
     rc = SSH_OK; \
     state(conn, SSH_AUTH_GSSAPI); \
     break; \
   } \
   else { \
-    MOVE_TO_TERTIARY_AUTH; \
+    MOVE_TO_KEY_AUTH; \
   }
 
 static
 int myssh_auth_interactive(struct connectdata *conn)
@@ -617,6 +617,16 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
         }
 
         sshc->auth_methods = ssh_userauth_list(sshc->ssh_session, NULL);
+        if(sshc->auth_methods)
+          infof(data, "SSH authentication methods available: %s%s%s%s",
+                sshc->auth_methods & SSH_AUTH_METHOD_PUBLICKEY ?
+                "public key, ": "",
+                sshc->auth_methods & SSH_AUTH_METHOD_GSSAPI_MIC ?
+                "GSSAPI, " : "",
+                sshc->auth_methods & SSH_AUTH_METHOD_INTERACTIVE ?
+                "keyboard-interactive, " : "",
+                sshc->auth_methods & SSH_AUTH_METHOD_PASSWORD ?
+                "password": "");
         if(sshc->auth_methods & SSH_AUTH_METHOD_PUBLICKEY) {
           state(conn, SSH_AUTH_PKEY_INIT);
           infof(data, "Authentication using SSH public key file\n");
@@ -761,8 +761,8 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
       }
     case SSH_AUTH_PKEY_INIT:
       if(!(data->set.ssh_auth_types & CURLSSH_AUTH_PUBLICKEY)) {
-        MOVE_TO_SECONDARY_AUTH;
+        MOVE_TO_GSSAPI_AUTH;
       }
 
       /* Two choices, (1) private key was given on CMD,
        * (2) use the "default" keys. */
@@ -776,7 +776,7 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
           }
 
           if(rc != SSH_OK) {
-            MOVE_TO_SECONDARY_AUTH;
+            MOVE_TO_GSSAPI_AUTH;
           }
         }
 
@@ -826,7 +836,7 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
           break;
         }
 
-        MOVE_TO_SECONDARY_AUTH;
+        MOVE_TO_GSSAPI_AUTH;
       }
       break;
     case SSH_AUTH_PKEY:
@@ -828,13 +828,13 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
       }
       else {
         infof(data, "Failed public key authentication (rc: %d)\n", rc);
-        MOVE_TO_SECONDARY_AUTH;
+        MOVE_TO_GSSAPI_AUTH;
       }
       break;
 
     case SSH_AUTH_GSSAPI:
       if(!(data->set.ssh_auth_types & CURLSSH_AUTH_GSSAPI)) {
-        MOVE_TO_TERTIARY_AUTH;
+        MOVE_TO_KEY_AUTH;
       }
 
       rc = ssh_userauth_gssapi(sshc->ssh_session);
@@ -851,7 +851,7 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
         break;
       }
 
-      MOVE_TO_TERTIARY_AUTH;
+      MOVE_TO_KEY_AUTH;
       break;
 
     case SSH_AUTH_KEY_INIT:
@@ -736,13 +736,12 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
         state(conn, SSH_AUTH_KEY);
       }
       else {
-        MOVE_TO_LAST_AUTH;
+        MOVE_TO_PASSWD_AUTH;
       }
       break;
 
     case SSH_AUTH_KEY:
-
-      /* Authentication failed. Continue with keyboard-interactive now. */
+      /* keyboard-interactive authentication */
       rc = myssh_auth_interactive(conn);
       if(rc == SSH_AGAIN) {
         break;
@@ -759,13 +759,15 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
       if(rc == SSH_OK) {
         sshc->authed = TRUE;
         infof(data, "completed keyboard interactive authentication\n");
+        state(conn, SSH_AUTH_DONE);
+      }
+      else {
+        MOVE_TO_PASSWD_AUTH;
       }
-      state(conn, SSH_AUTH_DONE);
       break;
 
     case SSH_AUTH_PASS_INIT:
       if(!(data->set.ssh_auth_types & CURLSSH_AUTH_PASSWORD)) {
-        /* Host key authentication is intentionally not implemented */
         MOVE_TO_ERROR_STATE(CURLE_LOGIN_DENIED);
       }
       state(conn, SSH_AUTH_PASS);