qemu_agent: add qemuAgentSSH{Add,Remove,Get}AuthorizedKeys

In QEMU 5.2, the guest agent learned to manipulate a user
~/.ssh/authorized_keys. Bind the JSON API to libvirt.

https://wiki.qemu.org/ChangeLog/5.2#Guest_agent

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

src/qemu/qemu_agent.c

@@ -2496,3 +2496,144 @@ qemuAgentSetResponseTimeout(qemuAgentPtr agent,
 {
     agent->timeout = timeout;
 }
+
+/**
+ * qemuAgentSSHGetAuthorizedKeys:
+ * @agent: agent object
+ * @user: user to get authorized keys for
+ * @keys: Array of authorized keys
+ *
+ * Fetch the public keys from @user's $HOME/.ssh/authorized_keys.
+ *
+ * Returns: number of keys returned on success,
+ *          -1 otherwise (error is reported)
+ */
+int
+qemuAgentSSHGetAuthorizedKeys(qemuAgentPtr agent,
+                              const char *user,
+                              char ***keys)
+{
+    g_autoptr(virJSONValue) cmd = NULL;
+    g_autoptr(virJSONValue) reply = NULL;
+    virJSONValuePtr data = NULL;
+    size_t ndata;
+    size_t i;
+    char **keys_ret = NULL;
+
+    if (!(cmd = qemuAgentMakeCommand("guest-ssh-get-authorized-keys",
+                                     "s:username", user,
+                                     NULL)))
+        return -1;
+
+    if (qemuAgentCommand(agent, cmd, &reply, agent->timeout) < 0)
+        return -1;
+
+    if (!(data = virJSONValueObjectGetObject(reply, "return")) ||
+        !(data = virJSONValueObjectGetArray(data, "keys"))) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("qemu agent didn't return an array of keys"));
+        return -1;
+    }
+
+    ndata = virJSONValueArraySize(data);
+
+    keys_ret = g_new0(char *, ndata + 1);
+
+    for (i = 0; i < ndata; i++) {
+        virJSONValuePtr entry = virJSONValueArrayGet(data, i);
+
+        if (!entry) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("array element missing in guest-ssh-get-authorized-keys return value"));
+            goto error;
+        }
+
+        keys_ret[i] = g_strdup(virJSONValueGetString(entry));
+    }
+
+    *keys = g_steal_pointer(&keys_ret);
+    return ndata;
+
+ error:
+    virStringListFreeCount(keys_ret, ndata);
+    return -1;
+}
+
+
+/**
+ * qemuAgentSSHAddAuthorizedKeys:
+ * @agent: agent object
+ * @user: user to add authorized keys for
+ * @keys: Array of authorized keys
+ * @nkeys: number of items in @keys array
+ * @reset: whether to truncate authorized keys file before writing
+ *
+ * Append SSH @keys into the @user's authorized keys file. If
+ * @reset is true then the file is truncated before write and
+ * thus contains only newly added @keys.
+ *
+ * Returns: 0 on success,
+ *          -1 otherwise (error is reported)
+ */
+int
+qemuAgentSSHAddAuthorizedKeys(qemuAgentPtr agent,
+                              const char *user,
+                              const char **keys,
+                              size_t nkeys,
+                              bool reset)
+{
+    g_autoptr(virJSONValue) cmd = NULL;
+    g_autoptr(virJSONValue) reply = NULL;
+    g_autoptr(virJSONValue) jkeys = NULL;
+
+    jkeys = qemuAgentMakeStringsArray(keys, nkeys);
+    if (jkeys == NULL)
+        return -1;
+
+    if (!(cmd = qemuAgentMakeCommand("guest-ssh-add-authorized-keys",
+                                     "s:username", user,
+                                     "a:keys", &jkeys,
+                                     "b:reset", reset,
+                                     NULL)))
+        return -1;
+
+    return qemuAgentCommand(agent, cmd, &reply, agent->timeout);
+}
+
+
+/**
+ * qemuAgentSSHRemoveAuthorizedKeys:
+ * @agent: agent object
+ * @user: user to remove authorized keys for
+ * @keys: Array of authorized keys
+ * @nkeys: number of items in @keys array
+ *
+ * Remove SSH @keys from the @user's authorized keys file. It's
+ * not considered an error when trying to remove a non-existent
+ * key.
+ *
+ * Returns: 0 on success,
+ *          -1 otherwise (error is reported)
+ */
+int
+qemuAgentSSHRemoveAuthorizedKeys(qemuAgentPtr agent,
+                                 const char *user,
+                                 const char **keys,
+                                 size_t nkeys)
+{
+    g_autoptr(virJSONValue) cmd = NULL;
+    g_autoptr(virJSONValue) reply = NULL;
+    g_autoptr(virJSONValue) jkeys = NULL;
+
+    jkeys = qemuAgentMakeStringsArray(keys, nkeys);
+    if (jkeys == NULL)
+        return -1;
+
+    if (!(cmd = qemuAgentMakeCommand("guest-ssh-remove-authorized-keys",
+                                     "s:username", user,
+                                     "a:keys", &jkeys,
+                                     NULL)))
+        return -1;
+
+    return qemuAgentCommand(agent, cmd, &reply, agent->timeout);
+}

src/qemu/qemu_agent.h

@@ -170,3 +170,18 @@ int qemuAgentGetTimezone(qemuAgentPtr mon,
 
 void qemuAgentSetResponseTimeout(qemuAgentPtr mon,
                                  int timeout);
+
+int qemuAgentSSHGetAuthorizedKeys(qemuAgentPtr agent,
+                                  const char *user,
+                                  char ***keys);
+
+int qemuAgentSSHAddAuthorizedKeys(qemuAgentPtr agent,
+                                  const char *user,
+                                  const char **keys,
+                                  size_t nkeys,
+                                  bool reset);
+
+int qemuAgentSSHRemoveAuthorizedKeys(qemuAgentPtr agent,
+                                     const char *user,
+                                     const char **keys,
+                                     size_t nkeys);

tests/qemuagenttest.c

@@ -35,6 +35,84 @@
 virQEMUDriver driver;
 
 
+static int
+testQemuAgentSSHKeys(const void *data)
+{
+    virDomainXMLOptionPtr xmlopt = (virDomainXMLOptionPtr)data;
+    qemuMonitorTestPtr test = qemuMonitorTestNewAgent(xmlopt);
+    char **keys = NULL;
+    int nkeys = 0;
+    int ret = -1;
+
+    if (!test)
+        return -1;
+
+    if (qemuMonitorTestAddAgentSyncResponse(test) < 0)
+        goto cleanup;
+
+    if (qemuMonitorTestAddItem(test, "guest-ssh-get-authorized-keys",
+                               "{\"return\": {"
+                               "  \"keys\": ["
+                               "    \"algo1 key1 comments1\","
+                               "    \"algo2 key2 comments2\""
+                               "  ]"
+                               "}}") < 0)
+        goto cleanup;
+
+    if (qemuMonitorTestAddAgentSyncResponse(test) < 0)
+        goto cleanup;
+
+    if (qemuMonitorTestAddItem(test, "guest-ssh-add-authorized-keys",
+                               "{ \"return\" : {} }") < 0)
+        goto cleanup;
+
+    if (qemuMonitorTestAddAgentSyncResponse(test) < 0)
+        goto cleanup;
+
+    if (qemuMonitorTestAddItem(test, "guest-ssh-remove-authorized-keys",
+                               "{ \"return\" : {} }") < 0)
+        goto cleanup;
+
+    if ((nkeys = qemuAgentSSHGetAuthorizedKeys(qemuMonitorTestGetAgent(test),
+                                               "user",
+                                               &keys)) < 0)
+        goto cleanup;
+
+    if (nkeys != 2) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       "expected 2 keys, got %d", nkeys);
+        ret = -1;
+        goto cleanup;
+    }
+
+    if (STRNEQ(keys[1], "algo2 key2 comments2")) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "Unexpected key returned: %s", keys[1]);
+        ret = -1;
+        goto cleanup;
+    }
+
+    if ((ret = qemuAgentSSHAddAuthorizedKeys(qemuMonitorTestGetAgent(test),
+                                             "user",
+                                             (const char **) keys,
+                                             nkeys,
+                                             true)) < 0)
+        goto cleanup;
+
+    if ((ret = qemuAgentSSHRemoveAuthorizedKeys(qemuMonitorTestGetAgent(test),
+                                                "user",
+                                                (const char **) keys,
+                                                nkeys)) < 0)
+        goto cleanup;
+
+    ret = 0;
+
+ cleanup:
+    virStringListFreeCount(keys, nkeys);
+    qemuMonitorTestFree(test);
+    return ret;
+}
+
+
 static int
 testQemuAgentFSFreeze(const void *data)
 {
@@ -1315,6 +1393,7 @@ mymain(void)
     DO_TEST(Users);
     DO_TEST(OSInfo);
     DO_TEST(Timezone);
+    DO_TEST(SSHKeys);
 
     DO_TEST(Timeout); /* Timeout should always be called last */