Adding upstream version 1.9.13p3.upstream/1.9.13p3upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 813 insertions, 0 deletions

diff --git a/plugins/sudoers/sssd.c b/plugins/sudoers/sssd.c
new file mode 100644
index 0000000..d4c70b9
--- /dev/null
+++ b/plugins/sudoers/sssd.c
@@ -0,0 +1,813 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2003-2022 Todd C. Miller <Todd.Miller@sudo.ws>
+ * Copyright (c) 2011 Daniel Kopecek <dkopecek@redhat.com>
+ *
+ * This code is derived from software contributed by Aaron Spangler.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#ifdef HAVE_SSSD
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif /* HAVE_STRINGS_H */
+#include <ctype.h>
+#include <errno.h>
+#include <pwd.h>
+
+#include "sudoers.h"
+#include "sudo_lbuf.h"
+#include "sudo_ldap.h"
+#include "sudo_dso.h"
+
+/* SSSD <--> SUDO interface - do not change */
+struct sss_sudo_attr {
+    char *name;
+    char **values;
+    unsigned int num_values;
+};
+
+struct sss_sudo_rule {
+    unsigned int num_attrs;
+    struct sss_sudo_attr *attrs;
+};
+
+struct sss_sudo_result {
+    unsigned int num_rules;
+    struct sss_sudo_rule *rules;
+};
+
+typedef int  (*sss_sudo_send_recv_t)(uid_t, const char*, const char*,
+                                     uint32_t*, struct sss_sudo_result**);
+
+typedef int  (*sss_sudo_send_recv_defaults_t)(uid_t, const char*, uint32_t*,
+                                              char**, struct sss_sudo_result**);
+
+typedef void (*sss_sudo_free_result_t)(struct sss_sudo_result*);
+
+typedef int  (*sss_sudo_get_values_t)(struct sss_sudo_rule*, const char*,
+                                      char***);
+
+typedef void (*sss_sudo_free_values_t)(char**);
+
+/* sudo_nss handle */
+struct sudo_sss_handle {
+    char *domainname;
+    char *ipa_host;
+    char *ipa_shost;
+    struct passwd *pw;
+    void *ssslib;
+    struct sudoers_parse_tree parse_tree;
+    sss_sudo_send_recv_t fn_send_recv;
+    sss_sudo_send_recv_defaults_t fn_send_recv_defaults;
+    sss_sudo_free_result_t fn_free_result;
+    sss_sudo_get_values_t fn_get_values;
+    sss_sudo_free_values_t fn_free_values;
+};
+
+static int
+get_ipa_hostname(char **shostp, char **lhostp)
+{
+    size_t linesize = 0;
+    char *lhost = NULL;
+    char *shost = NULL;
+    char *line = NULL;
+    int ret = false;
+    ssize_t len;
+    FILE *fp;
+    debug_decl(get_ipa_hostname, SUDOERS_DEBUG_SSSD);
+
+    fp = fopen(_PATH_SSSD_CONF, "r");
+    if (fp != NULL) {
+	while ((len = getdelim(&line, &linesize, '\n', fp)) != -1) {
+	    char *cp = line;
+
+	    /* Trim trailing and leading spaces. */
+	    while (len > 0 && isspace((unsigned char)line[len - 1]))
+		line[--len] = '\0';
+	    while (isspace((unsigned char)*cp))
+		cp++;
+
+	    /*
+	     * Match ipa_hostname = foo
+	     * Note: currently ignores the domain (XXX)
+	     */
+	    if (strncmp(cp, "ipa_hostname", 12) == 0) {
+		cp += 12;
+		/* Trim " = " after "ipa_hostname" */
+		while (isblank((unsigned char)*cp))
+		    cp++;
+		if (*cp++ != '=')
+		    continue;
+		while (isblank((unsigned char)*cp))
+		    cp++;
+		/* Ignore empty value */
+		if (*cp == '\0')
+		    continue;
+		lhost = strdup(cp);
+		if (lhost != NULL && (cp = strchr(lhost, '.')) != NULL) {
+		    shost = strndup(lhost, (size_t)(cp - lhost));
+		} else {
+		    shost = lhost;
+		}
+		if (shost != NULL && lhost != NULL) {
+		    sudo_debug_printf(SUDO_DEBUG_INFO,
+			"ipa_hostname %s overrides %s", lhost, user_host);
+		    *shostp = shost;
+		    *lhostp = lhost;
+		    ret = true;
+		} else {
+		    sudo_warnx(U_("%s: %s"), __func__,
+			U_("unable to allocate memory"));
+		    free(shost);
+		    free(lhost);
+		    ret = -1;
+		}
+		break;
+	    }
+	}
+	fclose(fp);
+	free(line);
+    }
+    debug_return_int(ret);
+}
+
+/*
+ * SSSD doesn't handle netgroups, we have to ensure they are correctly filtered
+ * in sudo. The rules may contain mixed sudoUser specification so we have to
+ * check not only for netgroup membership but also for user and group matches.
+ * Otherwise, a netgroup non-match could override a user/group match.
+ */
+static bool
+sudo_sss_check_user(struct sudo_sss_handle *handle, struct sss_sudo_rule *rule)
+{
+    const char *host = handle->ipa_host ? handle->ipa_host : user_runhost;
+    const char *shost = handle->ipa_shost ? handle->ipa_shost : user_srunhost;
+    char **val_array;
+    int i, rc, ret = false;
+    debug_decl(sudo_sss_check_user, SUDOERS_DEBUG_SSSD);
+
+    if (rule == NULL)
+	debug_return_bool(false);
+
+    rc = handle->fn_get_values(rule, "sudoUser", &val_array);
+    switch (rc) {
+    case 0:
+	break;
+    case ENOENT:
+	sudo_debug_printf(SUDO_DEBUG_INFO, "No result.");
+	debug_return_bool(false);
+    case ENOMEM:
+	sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	FALLTHROUGH;
+    default:
+	sudo_debug_printf(SUDO_DEBUG_ERROR,
+	    "handle->fn_get_values(sudoOption): rc=%d", rc);
+	debug_return_bool(false);
+    }
+
+    /* Walk through sudoUser values.  */
+    for (i = 0; val_array[i] != NULL && !ret; ++i) {
+	const char *val = val_array[i];
+	bool negated = false;
+
+	sudo_debug_printf(SUDO_DEBUG_DEBUG, "val[%d]=%s", i, val);
+	if (*val == '!') {
+	    val++;
+	    negated = true;
+	}
+	switch (*val) {
+	case '+':
+	    /* Netgroup spec found, check membership. */
+	    if (netgr_matches(val, def_netgroup_tuple ? host : NULL,
+		def_netgroup_tuple ? shost : NULL, handle->pw->pw_name)) {
+		ret = true;
+	    }
+	    break;
+	case '%':
+	    /* User group found, check membership. */
+	    if (usergr_matches(val, handle->pw->pw_name, handle->pw)) {
+		ret = true;
+	    }
+	    break;
+	default:
+	    /* Not a netgroup or user group. */
+	    if (strcmp(val, "ALL") == 0 ||
+		userpw_matches(val, handle->pw->pw_name, handle->pw)) {
+		ret = true;
+	    }
+	    break;
+	}
+	sudo_debug_printf(SUDO_DEBUG_DIAG,
+	    "sssd/ldap sudoUser '%s%s' ... %s (%s)", negated ? "!" : "",
+	    val, ret ? "MATCH!" : "not", handle->pw->pw_name);
+
+	/* A negated match overrides all other entries. */
+	if (ret && negated) {
+	    ret = false;
+	    break;
+	}
+    }
+    handle->fn_free_values(val_array);
+    debug_return_bool(ret);
+}
+
+static char *
+val_array_iter(void **vp)
+{
+    char **val_array = *vp;
+
+    *vp = val_array + 1;
+
+    return *val_array;
+}
+
+/*
+ * Wrapper for sudo_ldap_role_to_priv() that takes an sss rule..
+ * Returns a struct privilege on success or NULL on failure.
+ */
+static struct privilege *
+sss_rule_to_priv(struct sudo_sss_handle *handle, struct sss_sudo_rule *rule,
+    int *rc_out)
+{
+    char **cmnds = NULL, **runasusers = NULL, **runasgroups = NULL;
+    char **opts = NULL, **notbefore = NULL, **notafter = NULL;
+    char **hosts = NULL, **cn_array = NULL, *cn = NULL;
+    struct privilege *priv = NULL;
+    int rc;
+    debug_decl(sss_rule_to_priv, SUDOERS_DEBUG_SSSD);
+
+    /* Ignore sudoRole without sudoCommand or sudoHost. */
+    rc = handle->fn_get_values(rule, "sudoCommand", &cmnds);
+    if (rc != 0)
+	goto cleanup;
+    rc = handle->fn_get_values(rule, "sudoHost", &hosts);
+    if (rc != 0)
+	goto cleanup;
+
+    /* Get the entry's dn for long format printing. */
+    rc = handle->fn_get_values(rule, "cn", &cn_array);
+    if (rc != 0)
+	goto cleanup;
+    cn = cn_array[0];
+
+    /* Get sudoRunAsUser / sudoRunAs */
+    rc = handle->fn_get_values(rule, "sudoRunAsUser", &runasusers);
+    switch (rc) {
+    case 0:
+	break;
+    case ENOENT:
+	rc = handle->fn_get_values(rule, "sudoRunAs", &runasusers);
+	switch (rc) {
+	    case 0:
+	    case ENOENT:
+		break;
+	    default:
+		goto cleanup;
+	}
+	break;
+    default:
+	goto cleanup;
+    }
+
+    /* Get sudoRunAsGroup */
+    rc = handle->fn_get_values(rule, "sudoRunAsGroup", &runasgroups);
+    switch (rc) {
+    case 0:
+    case ENOENT:
+	break;
+    default:
+	goto cleanup;
+    }
+
+    /* Get sudoNotBefore */
+    rc = handle->fn_get_values(rule, "sudoNotBefore", &notbefore);
+    switch (rc) {
+    case 0:
+    case ENOENT:
+	break;
+    default:
+	goto cleanup;
+    }
+
+    /* Get sudoNotAfter */
+    rc = handle->fn_get_values(rule, "sudoNotAfter", &notafter);
+    switch (rc) {
+    case 0:
+    case ENOENT:
+	break;
+    default:
+	goto cleanup;
+    }
+
+    /* Parse sudoOptions. */
+    rc = handle->fn_get_values(rule, "sudoOption", &opts);
+    switch (rc) {
+    case 0:
+    case ENOENT:
+	break;
+    default:
+	goto cleanup;
+    }
+
+    priv = sudo_ldap_role_to_priv(cn, hosts, runasusers, runasgroups,
+	cmnds, opts, notbefore ? notbefore[0] : NULL,
+	notafter ? notafter[0] : NULL, false, true, val_array_iter);
+    if (priv == NULL) {
+	rc = ENOMEM;
+	goto cleanup;
+    }
+    rc = 0;
+
+cleanup:
+    handle->fn_free_values(cn_array);
+    handle->fn_free_values(cmnds);
+    handle->fn_free_values(hosts);
+    handle->fn_free_values(runasusers);
+    handle->fn_free_values(runasgroups);
+    handle->fn_free_values(opts);
+    handle->fn_free_values(notbefore);
+    handle->fn_free_values(notafter);
+
+    *rc_out = rc;
+
+    debug_return_ptr(priv);
+}
+
+static bool
+sss_to_sudoers(struct sudo_sss_handle *handle,
+    struct sss_sudo_result *sss_result)
+{
+    struct userspec *us;
+    struct member *m;
+    unsigned int i;
+    debug_decl(sss_to_sudoers, SUDOERS_DEBUG_SSSD);
+
+    /* We only have a single userspec */
+    if ((us = calloc(1, sizeof(*us))) == NULL)
+	goto oom;
+    us->file = sudo_rcstr_dup("SSSD");
+    TAILQ_INIT(&us->users);
+    TAILQ_INIT(&us->privileges);
+    STAILQ_INIT(&us->comments);
+    TAILQ_INSERT_TAIL(&handle->parse_tree.userspecs, us, entries);
+
+    /* We only include rules where the user matches. */
+    if ((m = sudo_ldap_new_member_all()) == NULL)
+	goto oom;
+    TAILQ_INSERT_TAIL(&us->users, m, entries);
+
+    /*
+     * Treat each rule as a separate privilege.
+     *
+     * Sssd has already sorted the rules in descending order.
+     * The conversion to a sudoers parse tree requires that entries be
+     * in *ascending* order so we we iterate from last to first.
+     */
+    for (i = sss_result->num_rules; i-- > 0; ) {
+	struct sss_sudo_rule *rule = sss_result->rules + i;
+	struct privilege *priv;
+	int rc;
+
+	/*
+	 * We don't know whether a rule was included due to a user/group
+	 * match or because it contained a netgroup.
+	 */
+	if (!sudo_sss_check_user(handle, rule))
+	    continue;
+
+	if ((priv = sss_rule_to_priv(handle, rule, &rc)) == NULL) {
+	    if (rc == ENOMEM)
+		goto oom;
+	    continue;
+	}
+	TAILQ_INSERT_TAIL(&us->privileges, priv, entries);
+    }
+
+    debug_return_bool(true);
+
+oom:
+    sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+    free_userspecs(&handle->parse_tree.userspecs);
+    debug_return_bool(false);
+}
+
+static bool
+sudo_sss_parse_options(struct sudo_sss_handle *handle, struct sss_sudo_rule *rule, struct defaults_list *defs)
+{
+    int i, rc;
+    char *source = NULL;
+    bool ret = false;
+    char **val_array = NULL;
+    char **cn_array = NULL;
+    debug_decl(sudo_sss_parse_options, SUDOERS_DEBUG_SSSD);
+
+    if (rule == NULL)
+	debug_return_bool(true);
+
+    rc = handle->fn_get_values(rule, "sudoOption", &val_array);
+    switch (rc) {
+    case 0:
+	break;
+    case ENOENT:
+	sudo_debug_printf(SUDO_DEBUG_INFO, "No result.");
+	debug_return_bool(true);
+    case ENOMEM:
+	goto oom;
+    default:
+	sudo_debug_printf(SUDO_DEBUG_ERROR,
+	    "handle->fn_get_values(sudoOption): rc=%d", rc);
+	debug_return_bool(false);
+    }
+
+    /* Use sudoRole in place of file name in defaults. */
+    if (handle->fn_get_values(rule, "cn", &cn_array) == 0) {
+	if (cn_array[0] != NULL) {
+	    char *cp;
+	    if (asprintf(&cp, "sudoRole %s", cn_array[0]) == -1)
+		goto oom;
+	    source = sudo_rcstr_dup(cp);
+	    free(cp);
+	    if (source == NULL)
+		goto oom;
+	}
+	handle->fn_free_values(cn_array);
+	cn_array = NULL;
+    }
+    if (source == NULL) {
+	if ((source = sudo_rcstr_dup("sudoRole UNKNOWN")) == NULL)
+	    goto oom;
+    }
+
+    /* Walk through options, appending to defs. */
+    for (i = 0; val_array[i] != NULL; i++) {
+	char *var, *val;
+	int op;
+
+	op = sudo_ldap_parse_option(val_array[i], &var, &val);
+	if (!append_default(var, val, op, source, defs))
+	    goto oom;
+    }
+    ret = true;
+    goto done;
+
+oom:
+    sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+
+done:
+    sudo_rcstr_delref(source);
+    handle->fn_free_values(val_array);
+    debug_return_bool(ret);
+}
+
+static struct sss_sudo_result *
+sudo_sss_result_get(struct sudo_nss *nss, struct passwd *pw)
+{
+    struct sudo_sss_handle *handle = nss->handle;
+    struct sss_sudo_result *sss_result = NULL;
+    uint32_t sss_error = 0, rc;
+    debug_decl(sudo_sss_result_get, SUDOERS_DEBUG_SSSD);
+
+    sudo_debug_printf(SUDO_DEBUG_DIAG, "  username=%s", pw->pw_name);
+    sudo_debug_printf(SUDO_DEBUG_DIAG, "domainname=%s",
+	handle->domainname ? handle->domainname : "NULL");
+
+    rc = handle->fn_send_recv(pw->pw_uid, pw->pw_name,
+	handle->domainname, &sss_error, &sss_result);
+    switch (rc) {
+    case 0:
+	break;
+    case ENOMEM:
+	sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	FALLTHROUGH;
+    default:
+	sudo_debug_printf(SUDO_DEBUG_ERROR, "handle->fn_send_recv: rc=%d", rc);
+	debug_return_ptr(NULL);
+    }
+
+    switch (sss_error) {
+    case 0:
+	if (sss_result != NULL) {
+	    sudo_debug_printf(SUDO_DEBUG_INFO, "Received %u rule(s)",
+		sss_result->num_rules);
+	} else {
+	    sudo_debug_printf(SUDO_DEBUG_ERROR,
+		"Internal error: sss_result == NULL && sss_error == 0");
+	    debug_return_ptr(NULL);
+	}
+	break;
+    case ENOENT:
+	sudo_debug_printf(SUDO_DEBUG_INFO, "The user was not found in SSSD.");
+	debug_return_ptr(NULL);
+    default:
+	sudo_debug_printf(SUDO_DEBUG_ERROR, "sss_error=%u\n", sss_error);
+	debug_return_ptr(NULL);
+    }
+
+    debug_return_ptr(sss_result);
+}
+
+/* sudo_nss implementation */
+static int
+sudo_sss_close(struct sudo_nss *nss)
+{
+    struct sudo_sss_handle *handle = nss->handle;
+    debug_decl(sudo_sss_close, SUDOERS_DEBUG_SSSD);
+
+    if (handle != NULL) {
+	sudo_dso_unload(handle->ssslib);
+	if (handle->pw != NULL)
+	    sudo_pw_delref(handle->pw);
+	free_parse_tree(&handle->parse_tree);
+	free(handle);
+	nss->handle = NULL;
+    }
+    debug_return_int(0);
+}
+
+static int
+sudo_sss_open(struct sudo_nss *nss)
+{
+    struct sudo_sss_handle *handle;
+    static const char path[] = _PATH_SSSD_LIB"/libsss_sudo.so";
+    debug_decl(sudo_sss_open, SUDOERS_DEBUG_SSSD);
+
+    if (nss->handle != NULL) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR,
+	    "%s: called with non-NULL handle %p", __func__, nss->handle);
+	sudo_sss_close(nss);
+    }
+
+    /* Create a handle container. */
+    handle = calloc(1, sizeof(struct sudo_sss_handle));
+    if (handle == NULL) {
+	sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	debug_return_int(ENOMEM);
+    }
+
+    /* Load symbols */
+    handle->ssslib = sudo_dso_load(path, SUDO_DSO_LAZY);
+    if (handle->ssslib == NULL) {
+	const char *errstr = sudo_dso_strerror();
+	sudo_warnx(U_("unable to load %s: %s"), path,
+	    errstr ? errstr : "unknown error");
+	sudo_warnx("%s",
+	    U_("unable to initialize SSS source. Is SSSD installed on your machine?"));
+	free(handle);
+	debug_return_int(EFAULT);
+    }
+
+    handle->fn_send_recv =
+	sudo_dso_findsym(handle->ssslib, "sss_sudo_send_recv");
+    if (handle->fn_send_recv == NULL) {
+	sudo_warnx(U_("unable to find symbol \"%s\" in %s"), path,
+	   "sss_sudo_send_recv");
+	free(handle);
+	debug_return_int(EFAULT);
+    }
+
+    handle->fn_send_recv_defaults =
+	sudo_dso_findsym(handle->ssslib, "sss_sudo_send_recv_defaults");
+    if (handle->fn_send_recv_defaults == NULL) {
+	sudo_warnx(U_("unable to find symbol \"%s\" in %s"), path,
+	   "sss_sudo_send_recv_defaults");
+	free(handle);
+	debug_return_int(EFAULT);
+    }
+
+    handle->fn_free_result =
+	sudo_dso_findsym(handle->ssslib, "sss_sudo_free_result");
+    if (handle->fn_free_result == NULL) {
+	sudo_warnx(U_("unable to find symbol \"%s\" in %s"), path,
+	   "sss_sudo_free_result");
+	free(handle);
+	debug_return_int(EFAULT);
+    }
+
+    handle->fn_get_values =
+	sudo_dso_findsym(handle->ssslib, "sss_sudo_get_values");
+    if (handle->fn_get_values == NULL) {
+	sudo_warnx(U_("unable to find symbol \"%s\" in %s"), path,
+	   "sss_sudo_get_values");
+	free(handle);
+	debug_return_int(EFAULT);
+    }
+
+    handle->fn_free_values =
+	sudo_dso_findsym(handle->ssslib, "sss_sudo_free_values");
+    if (handle->fn_free_values == NULL) {
+	sudo_warnx(U_("unable to find symbol \"%s\" in %s"), path,
+	   "sss_sudo_free_values");
+	free(handle);
+	debug_return_int(EFAULT);
+    }
+
+    /*
+     * If runhost is the same as the local host, check for ipa_hostname
+     * in sssd.conf and use it in preference to user_runhost.
+     */
+    if (strcasecmp(user_runhost, user_host) == 0) {
+	if (get_ipa_hostname(&handle->ipa_shost, &handle->ipa_host) == -1) {
+	    free(handle);
+	    debug_return_int(ENOMEM);
+	}
+    }
+
+    /* The "parse tree" contains userspecs, defaults, aliases and hostnames. */
+    init_parse_tree(&handle->parse_tree, handle->ipa_host, handle->ipa_shost);
+    nss->handle = handle;
+
+    sudo_debug_printf(SUDO_DEBUG_DEBUG, "handle=%p", handle);
+
+    debug_return_int(0);
+}
+
+/*
+ * Perform query for user and host and convert to sudoers parse tree.
+ */
+static int
+sudo_sss_query(struct sudo_nss *nss, struct passwd *pw)
+{
+    struct sudo_sss_handle *handle = nss->handle;
+    struct sss_sudo_result *sss_result = NULL;
+    int ret = 0;
+    debug_decl(sudo_sss_query, SUDOERS_DEBUG_SSSD);
+
+    if (handle == NULL) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR,
+	    "%s: called with NULL handle", __func__);
+	debug_return_int(-1);
+    }
+
+    /* Use cached result if it matches pw. */
+    if (handle->pw != NULL) {
+	if (pw == handle->pw)
+	    goto done;
+	sudo_pw_delref(handle->pw);
+	handle->pw = NULL;
+    }
+
+    /* Free old userspecs, if any. */
+    free_userspecs(&handle->parse_tree.userspecs);
+
+    /* Fetch list of sudoRole entries that match user and host. */
+    sss_result = sudo_sss_result_get(nss, pw);
+
+    sudo_debug_printf(SUDO_DEBUG_DIAG,
+	"searching SSSD/LDAP for sudoers entries for user %s, host %s",
+	 pw->pw_name, user_runhost);
+
+    /* Stash a ref to the passwd struct in the handle. */
+    sudo_pw_addref(pw);
+    handle->pw = pw;
+
+    /* Convert to sudoers parse tree if the user was found. */
+    if (sss_result != NULL) {
+	if (!sss_to_sudoers(handle, sss_result)) {
+	    ret = -1;
+	    goto done;
+	}
+    }
+
+done:
+    /* Cleanup */
+    handle->fn_free_result(sss_result);
+    if (ret == -1) {
+	free_userspecs(&handle->parse_tree.userspecs);
+	if (handle->pw != NULL) {
+	    sudo_pw_delref(handle->pw);
+	    handle->pw = NULL;
+	}
+    }
+
+    sudo_debug_printf(SUDO_DEBUG_DIAG, "Done with LDAP searches");
+
+    debug_return_int(ret);
+}
+
+/*
+ * Return the initialized (but empty) sudoers parse tree.
+ * The contents will be populated by the getdefs() and query() functions.
+ */
+static struct sudoers_parse_tree *
+sudo_sss_parse(struct sudo_nss *nss)
+{
+    struct sudo_sss_handle *handle = nss->handle;
+    debug_decl(sudo_sss_parse, SUDOERS_DEBUG_SSSD);
+
+    if (handle == NULL) {
+    	sudo_debug_printf(SUDO_DEBUG_ERROR,
+	    "%s: called with NULL handle", __func__);
+	debug_return_ptr(NULL);
+    }
+
+    debug_return_ptr(&handle->parse_tree);
+}
+
+static int
+sudo_sss_getdefs(struct sudo_nss *nss)
+{
+    struct sudo_sss_handle *handle = nss->handle;
+    struct sss_sudo_result *sss_result = NULL;
+    static bool cached;
+    uint32_t sss_error;
+    unsigned int i;
+    int rc;
+    debug_decl(sudo_sss_getdefs, SUDOERS_DEBUG_SSSD);
+
+    if (handle == NULL) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR,
+	    "%s: called with NULL handle", __func__);
+	debug_return_int(-1);
+    }
+
+    /* Use cached result if present. */
+    if (cached)
+	debug_return_int(0);
+
+    sudo_debug_printf(SUDO_DEBUG_DIAG, "Looking for cn=defaults");
+
+    /* NOTE: these are global defaults, user-ID and name are not used. */
+    rc = handle->fn_send_recv_defaults(sudo_user.pw->pw_uid,
+	sudo_user.pw->pw_name, &sss_error, &handle->domainname, &sss_result);
+    switch (rc) {
+    case 0:
+	break;
+    case ENOMEM:
+	sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	debug_return_int(-1);
+    default:
+	/*
+	 * Unable to connect to the sudo SSSD connector.
+	 * SSSD may not be configured for sudo, treat as non-fatal.
+	 */
+	sudo_debug_printf(SUDO_DEBUG_ERROR,
+	    "handle->fn_send_recv_defaults: rc=%d, sss_error=%u", rc, sss_error);
+	debug_return_int(0);
+    }
+
+    switch (sss_error) {
+    case 0:
+	/* Success */
+	for (i = 0; i < sss_result->num_rules; ++i) {
+	    struct sss_sudo_rule *sss_rule = sss_result->rules + i;
+	    sudo_debug_printf(SUDO_DEBUG_DIAG,
+		"Parsing cn=defaults, %d/%d", i, sss_result->num_rules);
+	    if (!sudo_sss_parse_options(handle, sss_rule,
+		&handle->parse_tree.defaults))
+		goto bad;
+	}
+	break;
+    case ENOENT:
+	sudo_debug_printf(SUDO_DEBUG_INFO,
+	    "No global defaults entry found in SSSD.");
+	break;
+    default:
+	sudo_debug_printf(SUDO_DEBUG_ERROR, "sss_error=%u\n", sss_error);
+	goto bad;
+    }
+    handle->fn_free_result(sss_result);
+    cached = true;
+    debug_return_int(0);
+
+bad:
+    handle->fn_free_result(sss_result);
+    debug_return_int(-1);
+}
+
+/* sudo_nss implementation */
+struct sudo_nss sudo_nss_sss = {
+    { NULL, NULL },
+    "sss",
+    sudo_sss_open,
+    sudo_sss_close,
+    sudo_sss_parse,
+    sudo_sss_query,
+    sudo_sss_getdefs
+};
+
+#endif /* HAVE_SSSD */