ipa_server_mode: write capaths to krb5 include file

If there are member domains in a trusted forest which are DNS-wise not
proper children of the forest root the IPA KDC needs some help to
determine the right authentication path. In general this should be done
internally by the IPA KDC but this works requires more effort than
letting sssd write the needed data to the include file for krb5.conf.
If this functionality is available for the IPA KDC this patch might be
removed from the sssd tree.

Fixes https://fedorahosted.org/sssd/ticket/2093

2 files changed, 52 insertions, 2 deletions

diff --git a/src/util/domain_info_utils.c b/src/util/domain_info_utils.c
index 4af967cf..9d7bb5f5 100644
--- a/src/util/domain_info_utils.c
+++ b/src/util/domain_info_utils.c
@@ -336,9 +336,10 @@ sss_krb5_touch_config(void)
 }
 
 errno_t
-sss_write_domain_mappings(struct sss_domain_info *domain)
+sss_write_domain_mappings(struct sss_domain_info *domain, bool add_capaths)
 {
     struct sss_domain_info *dom;
+    struct sss_domain_info *parent_dom;
     errno_t ret;
     errno_t err;
     TALLOC_CTX *tmp_ctx;
@@ -349,6 +350,9 @@ sss_write_domain_mappings(struct sss_domain_info *domain)
     mode_t old_mode;
     FILE *fstream = NULL;
     int i;
+    bool capaths_started;
+    char *uc_forest;
+    char *uc_parent;
 
     if (domain == NULL || domain->name == NULL) {
         DEBUG(SSSDBG_CRIT_FAILURE, ("No domain name provided\n"));
@@ -434,6 +438,51 @@ sss_write_domain_mappings(struct sss_domain_info *domain)
         }
     }
 
+    if (add_capaths) {
+        capaths_started = false;
+        parent_dom = domain;
+        uc_parent = get_uppercase_realm(tmp_ctx, parent_dom->name);
+        if (uc_parent == NULL) {
+            DEBUG(SSSDBG_OP_FAILURE, ("get_uppercase_realm failed.\n"));
+            ret = ENOMEM;
+            goto done;
+        }
+
+        for (dom = get_next_domain(domain, true);
+             dom && IS_SUBDOMAIN(dom); /* if we get back to a parent, stop */
+             dom = get_next_domain(dom, false)) {
+
+            if (dom->forest == NULL) {
+                continue;
+            }
+
+            uc_forest = get_uppercase_realm(tmp_ctx, dom->forest);
+            if (uc_forest == NULL) {
+                DEBUG(SSSDBG_OP_FAILURE, ("get_uppercase_realm failed.\n"));
+                ret = ENOMEM;
+                goto done;
+            }
+
+            if (!capaths_started) {
+                ret = fprintf(fstream, "[capaths]\n");
+                if (ret < 0) {
+                    DEBUG(SSSDBG_OP_FAILURE, ("fprintf failed\n"));
+                    ret = EIO;
+                    goto done;
+                }
+                capaths_started = true;
+            }
+
+            ret = fprintf(fstream, "%s = {\n  %s = %s\n}\n%s = {\n  %s = %s\n}\n",
+                                   dom->realm, uc_parent, uc_forest,
+                                   uc_parent, dom->realm, uc_forest);
+            if (ret < 0) {
+                DEBUG(SSSDBG_CRIT_FAILURE, ("fprintf failed\n"));
+                goto done;
+            }
+        }
+    }
+
     ret = fclose(fstream);
     fstream = NULL;
     if (ret != 0) {
diff --git a/src/util/util.h b/src/util/util.h
index bd450ec7..98b86e9d 100644
--- a/src/util/util.h
+++ b/src/util/util.h
@@ -577,7 +577,8 @@ errno_t sssd_domain_init(TALLOC_CTX *mem_ctx,
 
 #define IS_SUBDOMAIN(dom) ((dom)->parent != NULL)
 
-errno_t sss_write_domain_mappings(struct sss_domain_info *domain);
+errno_t sss_write_domain_mappings(struct sss_domain_info *domain,
+                                  bool add_capaths);
 
 /* from util_lock.c */
 errno_t sss_br_lock_file(int fd, size_t start, size_t len,