PAM: Add support for more native pam features and initial support for gdm

.github/workflows/qa.yaml

@@ -12,6 +12,11 @@ jobs:
     name: Code sanity
     runs-on: ubuntu-latest
     steps:
+      - name: Install dependencies
+        uses: awalsh128/cache-apt-pkgs-action@latest
+        with:
+          packages: libgdm-dev libpam0g-dev
+          version: 1.0
       - uses: actions/checkout@v3
       - name: Go code sanity check
         uses: canonical/desktop-engineering/gh-actions/go/code-sanity@main
@@ -23,6 +28,11 @@ jobs:
     name: Tests
     runs-on: ubuntu-latest
     steps:
+      - name: Install dependencies
+        uses: awalsh128/cache-apt-pkgs-action@latest
+        with:
+          packages: libgdm-dev libpam0g-dev
+          version: 1.0
       - uses: actions/checkout@v3
       - uses: actions/setup-go@v4
         with:

go.mod

@@ -23,6 +23,7 @@ require (
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/elliotchance/orderedmap/v2 v2.2.0 // indirect
 	github.com/fsnotify/fsnotify v1.6.0 // indirect
 	github.com/golang/protobuf v1.5.3 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect

go.sum

@@ -52,6 +52,8 @@ github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46t
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/elliotchance/orderedmap/v2 v2.2.0 h1:7/2iwO98kYT4XkOjA9mBEIwvi4KpGB4cyHeOFOnj4Vk=
+github.com/elliotchance/orderedmap/v2 v2.2.0/go.mod h1:85lZyVbpGaGvHvnKa7Qhx7zncAdBIBq6u56Hb1PRU5Q=
 github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1mIlRU8Am5FuJP05cCM98=

pam/pam-utils.c

@@ -0,0 +1,121 @@
+#include "pam-utils.h"
+
+#include <security/pam_appl.h>
+#include <assert.h>
+
+char *
+argv_string_get (const char **argv, unsigned i)
+{
+  return strdup (argv[i]);
+}
+
+char *
+get_user (pam_handle_t *pamh, const char *prompt)
+{
+  if (!pamh)
+    return NULL;
+  int pam_err = 0;
+  const char *user;
+
+  if ((pam_err = pam_get_user (pamh, &user, prompt)) != PAM_SUCCESS)
+    return NULL;
+  return strdup (user);
+}
+
+const char *
+get_module_name (pam_handle_t *pamh)
+{
+  const char *module_name;
+
+  if (pam_get_item (pamh, PAM_SERVICE, (const void **) &module_name) != PAM_SUCCESS)
+    return NULL;
+
+  return module_name;
+}
+
+static struct pam_response *
+send_msg_generic (pam_handle_t *pamh, const struct pam_message *pam_msg)
+{
+  const struct pam_conv *pc;
+  struct pam_response *resp;
+
+  if (pam_get_item (pamh, PAM_CONV, (const void **) &pc) != PAM_SUCCESS)
+    return NULL;
+
+  if (!pc || !pc->conv)
+    return NULL;
+
+  if (pc->conv (1, (const struct pam_message *[]){ pam_msg }, &resp,
+                pc->appdata_ptr) != PAM_SUCCESS)
+    return NULL;
+
+  return resp;
+}
+
+struct pam_response *
+send_msg (pam_handle_t *pamh, const char *msg, int style)
+{
+  const struct pam_message pam_msg = {
+    .msg_style = style,
+    .msg = msg,
+  };
+
+  return send_msg_generic (pamh, &pam_msg);
+}
+
+GdmPamExtensionChoiceListRequest *
+gdm_choices_request_create (const char *title,
+                            size_t      num)
+{
+  GdmPamExtensionChoiceListRequest *request;
+
+  request = calloc (1, GDM_PAM_EXTENSION_CHOICE_LIST_REQUEST_SIZE (num));
+  GDM_PAM_EXTENSION_CHOICE_LIST_REQUEST_INIT (request, (char *) title, num);
+
+  return request;
+}
+
+void
+gdm_choices_request_set (GdmPamExtensionChoiceListRequest *request, size_t i,
+                         const char *key, const char *text)
+{
+  assert (request != NULL && i < request->list.number_of_items);
+
+  request->list.items[i].key = strdup (key);
+  request->list.items[i].text = strdup (text);
+}
+
+void
+gdm_choices_request_free (GdmPamExtensionChoiceListRequest *request)
+{
+  assert (request != NULL);
+
+  for (size_t i = 0; i < request->list.number_of_items; ++i)
+    {
+      free ((char *) request->list.items[i].key);
+      free ((char *) request->list.items[i].text);
+    }
+
+  free (request);
+}
+
+char *
+gdm_choices_request_ask (pam_handle_t *pamh, GdmPamExtensionChoiceListRequest *request)
+{
+  GdmPamExtensionChoiceListResponse *response;
+  struct pam_message prompt_message;
+  struct pam_response *reply;
+  char *ret_key;
+
+  GDM_PAM_EXTENSION_MESSAGE_TO_BINARY_PROMPT_MESSAGE (request, &prompt_message);
+  reply = send_msg_generic (pamh, &prompt_message);
+
+  if (!reply)
+    return NULL;
+
+  response = GDM_PAM_EXTENSION_REPLY_TO_CHOICE_LIST_RESPONSE (reply);
+  ret_key = strdup (response->key);
+  free (response);
+
+  return ret_key;
+}

pam/pam-utils.h

@@ -0,0 +1,37 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <gdm/gdm-pam-extensions.h>
+#include <security/pam_modules.h>
+
+char *argv_string_get (const char **argv,
+                       unsigned     i);
+
+char *get_user (pam_handle_t *pamh,
+                const char   *prompt);
+
+const char *get_module_name (pam_handle_t *pamh);
+
+struct pam_response *send_msg (pam_handle_t *pamh,
+                               const char   *msg,
+                               int           style);
+
+inline bool
+gdm_choices_list_supported (void)
+{
+  return GDM_PAM_EXTENSION_SUPPORTED (GDM_PAM_EXTENSION_CHOICE_LIST);
+}
+
+GdmPamExtensionChoiceListRequest *gdm_choices_request_create (const char *,
+                                                              size_t);
+
+void gdm_choices_request_set (GdmPamExtensionChoiceListRequest *,
+                              size_t      i,
+                              const char *key,
+                              const char *value);
+
+char * gdm_choices_request_ask (pam_handle_t *pamh,
+                                GdmPamExtensionChoiceListRequest *);
+
+void gdm_choices_request_free (GdmPamExtensionChoiceListRequest *);