sssd/0023-files-add-support-for-Smartcard-authentication.patch

From 275eeed24adc31f3df51cf278f509a4be76a3a3c Mon Sep 17 00:00:00 2001
From: Sumit Bose <sbose@redhat.com>
Date: Mon, 9 Jul 2018 18:37:46 +0200
Subject: [PATCH 28/83] files: add support for Smartcard authentication

To support certificate based authentication the files provider must be
able to map a certificate to a user during a BE_REQ_BY_CERT request.

Additionally the authentication request should be handled by the PAM
responder code which is responsible for the local Smartcard
authentication. To be consistent with the other backend an authentication
handler is added to the files provider which unconditionally returns the
offline error code telling the PAM responder to handle the
authentication if it has access to the needed credentials.

Related to https://pagure.io/SSSD/sssd/issue/3500

Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
---
 Makefile.am                         |   2 +
 src/providers/files/files_auth.c    |  69 +++++++++++++
 src/providers/files/files_certmap.c | 186 ++++++++++++++++++++++++++++++++++++
 src/providers/files/files_id.c      |  20 ++++
 src/providers/files/files_init.c    |  21 +++-
 src/providers/files/files_private.h |  17 ++++
 6 files changed, 314 insertions(+), 1 deletion(-)
 create mode 100644 src/providers/files/files_auth.c
 create mode 100644 src/providers/files/files_certmap.c

diff --git a/Makefile.am b/Makefile.am
index deb9ce3..3667856 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -4285,6 +4285,8 @@ libsss_proxy_la_LDFLAGS = \
 libsss_files_la_SOURCES = \
     src/providers/files/files_init.c \
     src/providers/files/files_id.c \
+    src/providers/files/files_auth.c \
+    src/providers/files/files_certmap.c \
     src/providers/files/files_ops.c \
     src/util/inotify.c \
     $(NULL)
diff --git a/src/providers/files/files_auth.c b/src/providers/files/files_auth.c
new file mode 100644
index 0000000..b71de69
--- /dev/null
+++ b/src/providers/files/files_auth.c
@@ -0,0 +1,69 @@
+/*
+    SSSD
+
+    files_auth.c - PAM operations on the files provider
+
+    Copyright (C) 2018 Red Hat
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <security/pam_modules.h>
+
+#include "providers/data_provider/dp.h"
+#include "providers/data_provider.h"
+#include "providers/files/files_private.h"
+#include "util/cert.h"
+
+struct files_auth_ctx {
+    struct pam_data *pd;
+};
+
+struct tevent_req *
+files_auth_handler_send(TALLOC_CTX *mem_ctx,
+                        void *unused,
+                        struct pam_data *pd,
+                        struct dp_req_params *params)
+{
+    struct files_auth_ctx *state;
+    struct tevent_req *req;
+
+    req = tevent_req_create(mem_ctx, &state, struct files_auth_ctx);
+    if (req == NULL) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "tevent_req_create() failed\n");
+        return NULL;
+    }
+
+    state->pd = pd;
+    state->pd->pam_status = PAM_AUTHINFO_UNAVAIL;
+
+    tevent_req_done(req);
+    tevent_req_post(req, params->ev);
+    return req;
+}
+
+errno_t files_auth_handler_recv(TALLOC_CTX *mem_ctx,
+                                struct tevent_req *req,
+                                struct pam_data **_data)
+{
+    struct files_auth_ctx *state = NULL;
+
+    state = tevent_req_data(req, struct files_auth_ctx);
+
+    TEVENT_REQ_RETURN_ON_ERROR(req);
+
+    *_data = talloc_steal(mem_ctx, state->pd);
+
+    return EOK;
+}
diff --git a/src/providers/files/files_certmap.c b/src/providers/files/files_certmap.c
new file mode 100644
index 0000000..7d90a1f
--- /dev/null
+++ b/src/providers/files/files_certmap.c
@@ -0,0 +1,186 @@
+/*
+    SSSD
+
+    files_init.c - Initialization of the files provider
+
+    Copyright (C) 2018 Red Hat
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "providers/files/files_private.h"
+#include "util/util.h"
+#include "util/cert.h"
+#include "lib/certmap/sss_certmap.h"
+
+struct priv_sss_debug {
+    int level;
+};
+
+static void ext_debug(void *private, const char *file, long line,
+                      const char *function, const char *format, ...)
+{
+    va_list ap;
+    struct priv_sss_debug *data = private;
+    int level = SSSDBG_OP_FAILURE;
+
+    if (data != NULL) {
+        level = data->level;
+    }
+
+    if (DEBUG_IS_SET(level)) {
+        va_start(ap, format);
+        sss_vdebug_fn(file, line, function, level, APPEND_LINE_FEED,
+                      format, ap);
+        va_end(ap);
+    }
+}
+
+errno_t files_init_certmap(TALLOC_CTX *mem_ctx, struct files_id_ctx *id_ctx)
+{
+    int ret;
+    bool hint;
+    struct certmap_info **certmap_list = NULL;
+    size_t c;
+
+    ret = sysdb_get_certmap(mem_ctx, id_ctx->be->domain->sysdb,
+                            &certmap_list, &hint);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE, "sysdb_get_certmap failed.\n");
+        goto done;
+    }
+
+    if (certmap_list == NULL || *certmap_list == NULL) {
+        DEBUG(SSSDBG_TRACE_ALL, "No certmap data, nothing to do.\n");
+        ret = EOK;
+        goto done;
+    }
+
+    ret = sss_certmap_init(mem_ctx, ext_debug, NULL, &id_ctx->sss_certmap_ctx);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE, "sss_certmap_init failed.\n");
+        goto done;
+    }
+
+    for (c = 0; certmap_list[c] != NULL; c++) {
+        DEBUG(SSSDBG_TRACE_ALL, "Trying to add rule [%s][%d][%s][%s].\n",
+                                certmap_list[c]->name,
+                                certmap_list[c]->priority,
+                                certmap_list[c]->match_rule,
+                                certmap_list[c]->map_rule);
+
+        ret = sss_certmap_add_rule(id_ctx->sss_certmap_ctx,
+                                   certmap_list[c]->priority,
+                                   certmap_list[c]->match_rule,
+                                   certmap_list[c]->map_rule,
+                                   certmap_list[c]->domains);
+        if (ret != 0) {
+            DEBUG(SSSDBG_CRIT_FAILURE,
+                  "sss_certmap_add_rule failed for rule [%s] "
+                  "with error [%d][%s], skipping. "
+                  "Please check for typos and if rule syntax is supported.\n",
+                  certmap_list[c]->name, ret, sss_strerror(ret));
+            continue;
+        }
+    }
+
+    ret = EOK;
+
+done:
+    talloc_free(certmap_list);
+
+    return ret;
+}
+
+errno_t files_map_cert_to_user(struct files_id_ctx *id_ctx,
+                               struct dp_id_data *data)
+{
+    errno_t ret;
+    char *filter;
+    char *user;
+    struct ldb_message *msg = NULL;
+    struct sysdb_attrs *attrs = NULL;
+    TALLOC_CTX *tmp_ctx;
+
+    tmp_ctx = talloc_new(NULL);
+    if (tmp_ctx == NULL) {
+        DEBUG(SSSDBG_OP_FAILURE, "talloc_new failed.\n");
+        return ENOMEM;
+    }
+
+    ret = sss_cert_derb64_to_ldap_filter(tmp_ctx, data->filter_value, "",
+                                         id_ctx->sss_certmap_ctx,
+                                         id_ctx->domain, &filter);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE,
+              "sss_cert_derb64_to_ldap_filter failed.\n");
+        goto done;
+    }
+    if (filter == NULL || filter[0] != '('
+                       || filter[strlen(filter) - 1] != ')') {
+        DEBUG(SSSDBG_OP_FAILURE,
+              "sss_cert_derb64_to_ldap_filter returned bad filter [%s].\n",
+              filter);
+        ret = EINVAL;
+        goto done;
+    }
+
+    filter[strlen(filter) - 1] = '\0';
+    user = sss_create_internal_fqname(tmp_ctx, &filter[1],
+                                      id_ctx->domain->name);
+    if (user == NULL) {
+        DEBUG(SSSDBG_OP_FAILURE, "sss_create_internal_fqname failed.\n");
+        ret = ENOMEM;
+        goto done;
+    }
+    DEBUG(SSSDBG_TRACE_ALL, "Certificate mapped to user: [%s].\n", user);
+
+    ret = sysdb_search_user_by_name(tmp_ctx, id_ctx->domain, user, NULL, &msg);
+    if (ret == EOK) {
+        attrs = sysdb_new_attrs(tmp_ctx);
+        if (attrs == NULL) {
+            DEBUG(SSSDBG_OP_FAILURE, "sysdb_new_attrs failed.\n");
+            ret = ENOMEM;
+            goto done;
+        }
+
+        ret = sysdb_attrs_add_base64_blob(attrs, SYSDB_USER_MAPPED_CERT,
+                                          data->filter_value);
+        if (ret != EOK) {
+            DEBUG(SSSDBG_OP_FAILURE, "sysdb_attrs_add_base64_blob failed.\n");
+            goto done;
+        }
+
+        ret = sysdb_set_entry_attr(id_ctx->domain->sysdb, msg->dn, attrs,
+                                   SYSDB_MOD_ADD);
+        if (ret != EOK) {
+            DEBUG(SSSDBG_OP_FAILURE, "sysdb_set_entry_attr failed.\n");
+            goto done;
+        }
+    } else if (ret == ENOENT) {
+        DEBUG(SSSDBG_TRACE_ALL, "Mapped user [%s] not found.\n", user);
+        ret = EOK;
+        goto done;
+    } else {
+        DEBUG(SSSDBG_OP_FAILURE, "sysdb_search_user_by_name failed.\n");
+        goto done;
+    }
+
+    ret = EOK;
+
+done:
+    talloc_free(tmp_ctx);
+
+    return ret;
+}
diff --git a/src/providers/files/files_id.c b/src/providers/files/files_id.c
index 41314c6..f6f8c73 100644
--- a/src/providers/files/files_id.c
+++ b/src/providers/files/files_id.c
@@ -87,6 +87,26 @@ files_account_info_handler_send(TALLOC_CTX *mem_ctx,
                        ? true \
                        : false;
         break;
+    case BE_REQ_BY_CERT:
+        if (data->filter_type != BE_FILTER_CERT) {
+            DEBUG(SSSDBG_CRIT_FAILURE,
+                  "Unexpected filter type for lookup by cert: %d\n",
+                  data->filter_type);
+            ret = EINVAL;
+            goto immediate;
+        }
+        if (id_ctx->sss_certmap_ctx == NULL) {
+            DEBUG(SSSDBG_TRACE_ALL, "Certificate mapping not configured.\n");
+            ret = EOK;
+            goto immediate;
+        }
+
+        ret = files_map_cert_to_user(id_ctx, data);
+        if (ret != EOK) {
+            DEBUG(SSSDBG_OP_FAILURE, "files_map_cert_to_user failed");
+        }
+        goto immediate;
+        break;
     default:
         DEBUG(SSSDBG_CRIT_FAILURE,
               "Unexpected entry type: %d\n", data->entry_type & BE_REQ_TYPE_MASK);
diff --git a/src/providers/files/files_init.c b/src/providers/files/files_init.c
index c793bed..1ce4bcf 100644
--- a/src/providers/files/files_init.c
+++ b/src/providers/files/files_init.c
@@ -196,9 +196,16 @@ int sssm_files_init(TALLOC_CTX *mem_ctx,
               "Authentication with certificates/Smartcards might not work "
               "as expected.\n");
         /* not fatal, ignored */
+    } else {
+        ret = files_init_certmap(ctx, ctx);
+        if (ret != EOK) {
+            DEBUG(SSSDBG_CRIT_FAILURE, "files_init_certmap failed. "
+                  "Authentication with certificates/Smartcards might not work "
+                  "as expected.\n");
+            /* not fatal, ignored */
+        }
     }
 
-
     *_module_data = ctx;
     ret = EOK;
 done:
@@ -234,3 +241,15 @@ int sssm_files_id_init(TALLOC_CTX *mem_ctx,
 
     return EOK;
 }
+
+int sssm_files_auth_init(TALLOC_CTX *mem_ctx,
+                         struct be_ctx *be_ctx,
+                         void *module_data,
+                         struct dp_method *dp_methods)
+{
+    dp_set_method(dp_methods, DPM_AUTH_HANDLER,
+                  files_auth_handler_send, files_auth_handler_recv, NULL, void,
+                  struct pam_data, struct pam_data *);
+
+    return EOK;
+}
diff --git a/src/providers/files/files_private.h b/src/providers/files/files_private.h
index f44e6d4..fd17819 100644
--- a/src/providers/files/files_private.h
+++ b/src/providers/files/files_private.h
@@ -38,6 +38,7 @@ struct files_id_ctx {
     struct be_ctx *be;
     struct sss_domain_info *domain;
     struct files_ctx *fctx;
+    struct sss_certmap_ctx *sss_certmap_ctx;
 
     const char **passwd_files;
     const char **group_files;
@@ -71,4 +72,20 @@ errno_t files_account_info_handler_recv(TALLOC_CTX *mem_ctx,
 void files_account_info_finished(struct files_id_ctx *id_ctx,
                                  int req_type,
                                  errno_t ret);
+
+/* files_auth.c */
+struct tevent_req *files_auth_handler_send(TALLOC_CTX *mem_ctx,
+                                           void *unused,
+                                           struct pam_data *pd,
+                                           struct dp_req_params *params);
+
+errno_t files_auth_handler_recv(TALLOC_CTX *mem_ctx,
+                                struct tevent_req *req,
+                                struct pam_data **_data);
+
+/* files_certmap.c */
+errno_t files_init_certmap(TALLOC_CTX *mem_ctx, struct files_id_ctx *id_ctx);
+
+errno_t files_map_cert_to_user(struct files_id_ctx *id_ctx,
+                               struct dp_id_data *data);
 #endif /* __FILES_PRIVATE_H_ */
-- 
2.9.5