Add support for storing credential caches in the DIR: back end

https://fedorahosted.org/sssd/ticket/974

5 files changed, 510 insertions, 70 deletions

diff --git a/src/providers/krb5/krb5_child.c b/src/providers/krb5/krb5_child.c
index 195c431a..6b8722a8 100644
--- a/src/providers/krb5/krb5_child.c
+++ b/src/providers/krb5/krb5_child.c
@@ -221,6 +221,51 @@ done:
     return kerr;
 }
 
+static krb5_error_code
+store_creds_in_ccache(krb5_context ctx, krb5_principal princ,
+                      krb5_ccache cc, krb5_creds *creds)
+{
+    krb5_error_code kerr;
+    krb5_creds *l_cred;
+
+    kerr = krb5_cc_initialize(ctx, cc, princ);
+    if (kerr != 0) {
+        KRB5_DEBUG(SSSDBG_OP_FAILURE, kerr);
+        goto done;
+    }
+
+    if (creds == NULL) {
+        kerr = create_empty_cred(ctx, princ, &l_cred);
+        if (kerr != 0) {
+            KRB5_DEBUG(SSSDBG_OP_FAILURE, kerr);
+            goto done;
+        }
+    } else {
+        l_cred = creds;
+    }
+
+    kerr = krb5_cc_store_cred(ctx, cc, l_cred);
+    if (kerr != 0) {
+        KRB5_DEBUG(SSSDBG_OP_FAILURE, kerr);
+        goto done;
+    }
+
+    kerr = krb5_cc_switch(ctx, cc);
+    if (kerr != 0) {
+        KRB5_DEBUG(SSSDBG_OP_FAILURE, kerr);
+        goto done;
+    }
+
+    kerr = krb5_cc_close(ctx, cc);
+    if (kerr != 0) {
+        KRB5_DEBUG(SSSDBG_OP_FAILURE, kerr);
+        goto done;
+    }
+
+done:
+    return kerr;
+}
+
 static krb5_error_code create_ccache_file(krb5_context ctx,
                                           krb5_principal princ,
                                           char *ccname, krb5_creds *creds)
@@ -232,7 +277,6 @@ static krb5_error_code create_ccache_file(krb5_context ctx,
     size_t ccname_len;
     char *dummy;
     char *tmp_ccname;
-    krb5_creds *l_cred;
     TALLOC_CTX *tmp_ctx = NULL;
     mode_t old_umask;
 
@@ -285,38 +329,16 @@ static krb5_error_code create_ccache_file(krb5_context ctx,
         goto done;
     }
 
-    kerr = krb5_cc_initialize(ctx, tmp_cc, princ);
-    if (kerr != 0) {
-        KRB5_DEBUG(1, kerr);
-        goto done;
-    }
+    kerr = store_creds_in_ccache(ctx, princ, tmp_cc, creds);
     if (fd != -1) {
         close(fd);
         fd = -1;
     }
-
-    if (creds == NULL) {
-        kerr = create_empty_cred(ctx, princ, &l_cred);
-        if (kerr != 0) {
-            KRB5_DEBUG(1, kerr);
-            goto done;
-        }
-    } else {
-        l_cred = creds;
-    }
-
-    kerr = krb5_cc_store_cred(ctx, tmp_cc, l_cred);
     if (kerr != 0) {
         KRB5_DEBUG(1, kerr);
         goto done;
     }
 
-    kerr = krb5_cc_close(ctx, tmp_cc);
-    if (kerr != 0) {
-        KRB5_DEBUG(1, kerr);
-        goto done;
-    }
-    tmp_cc = NULL;
 
     ccname_len = strlen(cc_file_name);
     if (ccname_len >= 6 && strcmp(cc_file_name + (ccname_len-6), "XXXXXX")==0 ) {
@@ -338,16 +360,161 @@ static krb5_error_code create_ccache_file(krb5_context ctx,
     DEBUG(SSSDBG_TRACE_LIBS, ("Created ccache file: [%s]\n", ccname));
 
 done:
+    if (kerr != 0 && tmp_cc != NULL) {
+        krb5_cc_destroy(ctx, tmp_cc);
+    }
+
     if (fd != -1) {
         close(fd);
     }
+
+    talloc_free(tmp_ctx);
+    return kerr;
+}
+
+static errno_t
+create_ccdir(const char *dirname, uid_t uid, gid_t gid)
+{
+    mode_t old_umask;
+    struct stat statbuf;
+    errno_t ret;
+
+    old_umask = umask(0000);
+    ret = mkdir(dirname, 0700);
+    umask(old_umask);
+    if (ret == -1) {
+        /* Failing the mkdir is only OK if the directory already
+         * exists AND it is owned by the same user and group and
+         * has the correct permissions.
+         */
+        ret = errno;
+        if (ret == EEXIST) {
+            errno = 0;
+            ret = stat(dirname, &statbuf);
+            if (ret == -1) {
+                ret = errno;
+                DEBUG(SSSDBG_CRIT_FAILURE,
+                        ("stat failed [%d]: %s\n", ret, strerror(ret)));
+                return EIO;
+            }
+
+            if (statbuf.st_uid != uid || statbuf.st_gid != gid) {
+                DEBUG(SSSDBG_CRIT_FAILURE,
+                      ("The directory %s is owned by %d/%d, expected %d/%d\n",
+                       dirname, statbuf.st_uid, statbuf.st_gid, uid, gid));
+                return EACCES;
+            }
+
+            if ((statbuf.st_mode & ~S_IFMT) != 0700) {
+                DEBUG(SSSDBG_CRIT_FAILURE,
+                      ("The directory %s has wrong permissions %o, expected 0700\n",
+                       dirname, (statbuf.st_mode & ~S_IFMT)));
+                return EACCES;
+            }
+        } else {
+            DEBUG(SSSDBG_CRIT_FAILURE, ("mkdir [%s] failed [%d]: %s\n",
+                  dirname, ret, strerror(ret)));
+            return ret;
+        }
+    }
+
+    return EOK;
+}
+
+static krb5_error_code
+create_ccache_in_dir(uid_t uid, gid_t gid,
+                     krb5_context ctx,
+                     krb5_principal princ,
+                     char *ccname, krb5_creds *creds)
+{
+    krb5_error_code kerr;
+    krb5_ccache tmp_cc = NULL;
+    const char *dirname;
+
+    DEBUG(SSSDBG_FUNC_DATA, ("Creating ccache at [%s]\n", ccname));
+
+    dirname = sss_krb5_residual_check_type(ccname, SSS_KRB5_TYPE_DIR);
+    if (dirname == NULL) {
+        return EIO;
+    }
+
+    kerr = become_user(uid, gid);
+    if (kerr != EOK) {
+        DEBUG(SSSDBG_CRIT_FAILURE, ("become_user failed.\n"));
+        goto done;
+    }
+
+    if (dirname[0] == ':') {
+        /* Cache name in the form of DIR::filepath represents a single
+         * ccache in a collection that we are trying to reuse.
+         * See src/lib/krb5/ccache/cc_dir.c in the MIT Kerberos tree.
+         */
+        kerr = krb5_cc_resolve(ctx, ccname, &tmp_cc);
+        if (kerr != 0) {
+            KRB5_DEBUG(SSSDBG_OP_FAILURE, kerr);
+            goto done;
+        }
+    } else if (dirname[0] == '/') {
+        /* An absolute path denotes that krb5_child should create a new
+         * ccache. We can afford to just call mkdir(dirname) because we
+         * only want the last component to be created.
+         */
+
+        kerr = create_ccdir(dirname, uid, gid);
+        if (kerr) {
+            DEBUG(SSSDBG_OP_FAILURE,
+                  ("Cannot create directory %s\n", dirname));
+            goto done;
+        }
+
+        kerr = krb5_cc_set_default_name(ctx, ccname);
+        if (kerr != 0) {
+            KRB5_DEBUG(SSSDBG_OP_FAILURE, kerr);
+            goto done;
+        }
+
+        kerr = krb5_cc_new_unique(ctx, "DIR", NULL, &tmp_cc);
+        if (kerr != 0) {
+            KRB5_DEBUG(SSSDBG_OP_FAILURE, kerr);
+            goto done;
+        }
+    } else {
+        DEBUG(SSSDBG_CRIT_FAILURE,
+              ("Wrong residual format for DIR in ccache %s\n", ccname));
+        return EIO;
+    }
+
+    kerr = store_creds_in_ccache(ctx, princ, tmp_cc, creds);
+    if (kerr != 0) {
+        KRB5_DEBUG(SSSDBG_OP_FAILURE, kerr);
+        goto done;
+    }
+
+done:
     if (kerr != 0 && tmp_cc != NULL) {
         krb5_cc_destroy(ctx, tmp_cc);
     }
+    return kerr;
+}
 
-    talloc_free(tmp_ctx);
+static krb5_error_code
+create_ccache(uid_t uid, gid_t gid, krb5_context ctx,
+              krb5_principal princ, char *ccname, krb5_creds *creds)
+{
+    enum sss_krb5_cc_type cctype;
+
+    cctype = sss_krb5_get_type(ccname);
+    switch (cctype) {
+        case SSS_KRB5_TYPE_FILE:
+            return create_ccache_file(ctx, princ, ccname, creds);
+        case SSS_KRB5_TYPE_DIR:
+            return create_ccache_in_dir(uid, gid, ctx, princ, ccname, creds);
+        default:
+            DEBUG(SSSDBG_CRIT_FAILURE, ("Unknown cache type\n"));
+            return EINVAL;
+    }
 
-    return kerr;
+    return EINVAL;  /* Should never get here */
 }
 
 static errno_t pack_response_packet(struct response *resp, int status,
@@ -729,9 +896,9 @@ static krb5_error_code get_and_save_tgt(struct krb5_req *kr,
     }
 
     /* Use the updated principal in the creds in case canonicalized */
-    kerr = create_ccache_file(kr->ctx,
-                              kr->creds ? kr->creds->client : kr->princ,
-                              kr->ccname, kr->creds);
+    kerr = create_ccache(kr->uid, kr->gid, kr->ctx,
+                         kr->creds ? kr->creds->client : kr->princ,
+                         kr->ccname, kr->creds);
     if (kerr != 0) {
         KRB5_DEBUG(1, kerr);
         goto done;
@@ -1142,7 +1309,8 @@ static errno_t create_empty_ccache(int fd, struct krb5_req *kr)
 
     DEBUG(SSSDBG_TRACE_LIBS, ("Creating empty ccache\n"));
 
-    ret = create_ccache_file(kr->ctx, kr->princ, kr->ccname, NULL);
+    ret = create_ccache(kr->uid, kr->gid, kr->ctx,
+                        kr->princ, kr->ccname, NULL);
     if (ret != 0) {
         KRB5_DEBUG(1, ret);
         pam_status = PAM_SYSTEM_ERR;
diff --git a/src/providers/krb5/krb5_common.c b/src/providers/krb5/krb5_common.c
index 91816662..f4033d29 100644
--- a/src/providers/krb5/krb5_common.c
+++ b/src/providers/krb5/krb5_common.c
@@ -182,13 +182,37 @@ errno_t check_and_export_options(struct dp_option *opts,
     }
 
     cc_be = sss_krb5_get_type(dummy);
-    if (cc_be != SSS_KRB5_TYPE_FILE || dummy[0] != '/') {
-        DEBUG(SSSDBG_CONF_SETTINGS,
-              ("Currently only file based credential caches are supported "
-               "and krb5ccname_template must start with '/' or 'FILE:'\n"));
+    switch (cc_be) {
+    case SSS_KRB5_TYPE_FILE:
+        DEBUG(SSSDBG_CONF_SETTINGS, ("ccache is of type FILE\n"));
+        krb5_ctx->cc_be = &file_cc;
+        if (dummy[0] != '/') {
+            /* FILE:/path/to/cc */
+            break;
+        }
+
+        DEBUG(SSSDBG_CONF_SETTINGS, ("The ccname template was "
+              "missing an explicit type, but is an absolute "
+              "path specifier. Assuming FILE:\n"));
+
+        dummy = talloc_asprintf(opts, "FILE:%s", dummy);
+        if (!dummy) return ENOMEM;
+
+        ret = dp_opt_set_string(opts, KRB5_CCNAME_TMPL, dummy);
+        if (ret != EOK) {
+            DEBUG(SSSDBG_CRIT_FAILURE, ("dp_opt_set_string failed.\n"));
+            return ret;
+        }
+        break;
+    case SSS_KRB5_TYPE_DIR:
+        DEBUG(SSSDBG_CONF_SETTINGS, ("ccache is of type DIR\n"));
+        krb5_ctx->cc_be = &dir_cc;
+        break;
+    default:
+        DEBUG(SSSDBG_OP_FAILURE, ("Unkown ccname database\n"));
         return EINVAL;
+        break;
     }
-    krb5_ctx->cc_be = &file_cc;
 
     return EOK;
 }
diff --git a/src/providers/krb5/krb5_opts.h b/src/providers/krb5/krb5_opts.h
index 7f47290c..45dfec54 100644
--- a/src/providers/krb5/krb5_opts.h
+++ b/src/providers/krb5/krb5_opts.h
@@ -28,8 +28,8 @@
 struct dp_option default_krb5_opts[] = {
     { "krb5_server", DP_OPT_STRING, NULL_STRING, NULL_STRING },
     { "krb5_realm", DP_OPT_STRING, NULL_STRING, NULL_STRING },
-    { "krb5_ccachedir", DP_OPT_STRING, { "/tmp" }, NULL_STRING },
-    { "krb5_ccname_template", DP_OPT_STRING, { "FILE:%d/krb5cc_%U_XXXXXX" }, NULL_STRING},
+    { "krb5_ccachedir", DP_OPT_STRING, { "/run/user/%u" }, NULL_STRING },
+    { "krb5_ccname_template", DP_OPT_STRING, { "DIR:%d" }, NULL_STRING},
     { "krb5_auth_timeout", DP_OPT_NUMBER, { .number = 15 }, NULL_NUMBER },
     { "krb5_keytab", DP_OPT_STRING, { "/etc/krb5.keytab" }, NULL_STRING },
     { "krb5_validate", DP_OPT_BOOL, BOOL_FALSE, BOOL_FALSE },
diff --git a/src/providers/krb5/krb5_utils.c b/src/providers/krb5/krb5_utils.c
index 9f02fe33..35ece811 100644
--- a/src/providers/krb5/krb5_utils.c
+++ b/src/providers/krb5/krb5_utils.c
@@ -23,6 +23,7 @@
 */
 #include <string.h>
 #include <stdlib.h>
+#include <libgen.h>
 
 #include "providers/krb5/krb5_utils.h"
 #include "providers/krb5/krb5_auth.h"
@@ -330,7 +331,7 @@ check_ccache_re(const char *filename, pcre *illegal_re)
     return EFAULT;
 }
 
-static errno_t
+errno_t
 create_ccache_dir(const char *dirname, pcre *illegal_re,
                   uid_t uid, gid_t gid, bool private_path)
 {
@@ -518,6 +519,42 @@ done:
     return EOK;
 }
 
+static errno_t
+create_ccache_dir_head(const char *parent, pcre *illegal_re,
+                       uid_t uid, gid_t gid, bool private_path)
+{
+    char *dirname;
+    TALLOC_CTX *tmp_ctx = NULL;
+    char *end;
+    errno_t ret;
+
+    dirname = talloc_strdup(tmp_ctx, parent);
+    if (dirname == NULL) {
+        DEBUG(SSSDBG_CRIT_FAILURE, ("talloc_strdup failed.\n"));
+        ret = ENOMEM;
+        goto done;
+    }
+
+    /* We'll remove all trailing slashes from the back so that
+     * we only pass /some/path to find_ccdir_parent_data, not
+     * /some/path/ */
+    do {
+        end = strrchr(dirname, '/');
+        if (end == NULL || end == dirname) {
+            DEBUG(SSSDBG_CRIT_FAILURE, ("Cannot find parent directory of [%s], "
+                  "/ is not allowed.\n", dirname));
+            ret = EINVAL;
+            goto done;
+        }
+        *end = '\0';
+    } while (*(end+1) == '\0');
+
+    ret = create_ccache_dir(dirname, illegal_re, uid, gid, private_path);
+done:
+    talloc_free(tmp_ctx);
+    return ret;
+}
+
 /*======== ccache back end utilities ========*/
 struct sss_krb5_cc_be *
 get_cc_be_ops(enum sss_krb5_cc_type type)
@@ -528,6 +565,9 @@ get_cc_be_ops(enum sss_krb5_cc_type type)
         case SSS_KRB5_TYPE_FILE:
             be = &file_cc;
             break;
+        case SSS_KRB5_TYPE_DIR:
+            be = &dir_cc;
+            break;
         case SSS_KRB5_TYPE_UNKNOWN:
             be = NULL;
             break;
@@ -551,10 +591,6 @@ cc_file_create(const char *location, pcre *illegal_re,
                uid_t uid, gid_t gid, bool private_path)
 {
     const char *filename;
-    char *dirname;
-    char *end;
-    TALLOC_CTX *tmp_ctx = NULL;
-    errno_t ret;
 
     filename = sss_krb5_residual_check_type(location, SSS_KRB5_TYPE_FILE);
     if (filename == NULL) {
@@ -562,31 +598,7 @@ cc_file_create(const char *location, pcre *illegal_re,
         return EINVAL;
     }
 
-    tmp_ctx = talloc_new(NULL);
-    if (tmp_ctx == NULL) {
-        DEBUG(SSSDBG_CRIT_FAILURE, ("talloc_new failed.\n"));
-        return ENOMEM;
-    }
-
-    dirname = talloc_strdup(tmp_ctx, filename);
-    if (dirname == NULL) {
-        DEBUG(SSSDBG_CRIT_FAILURE, ("talloc_strdup failed.\n"));
-        ret = ENOMEM;
-        goto done;
-    }
-
-    end = strrchr(dirname, '/');
-    if (end == NULL || end == dirname) {
-        DEBUG(SSSDBG_CRIT_FAILURE, ("Missing filename in [%s].\n", dirname));
-        ret = EINVAL;
-        goto done;
-    }
-    *end = '\0';
-
-    ret = create_ccache_dir(dirname, illegal_re, uid, gid, private_path);
-done:
-    talloc_free(tmp_ctx);
-    return ret;
+    return create_ccache_dir_head(filename, illegal_re, uid, gid, private_path);
 }
 
 static errno_t
@@ -619,6 +631,9 @@ cc_residual_is_used(uid_t uid, const char *ccname,
         }
 
         switch (type) {
+            case SSS_KRB5_TYPE_DIR:
+                ret = S_ISDIR(stat_buf.st_mode);
+                break;
             case SSS_KRB5_TYPE_FILE:
                 ret = S_ISREG(stat_buf.st_mode);
                 break;
@@ -661,6 +676,9 @@ cc_file_check_existing(const char *location, uid_t uid,
     bool active;
     bool valid;
     const char *filename;
+    krb5_ccache ccache = NULL;
+    krb5_context context = NULL;
+    krb5_error_code kerr;
 
     filename = sss_krb5_residual_check_type(location, SSS_KRB5_TYPE_FILE);
     if (!filename) {
@@ -679,11 +697,26 @@ cc_file_check_existing(const char *location, uid_t uid,
         return ret;
     }
 
-    ret = check_for_valid_tgt(location, realm, princ, &valid);
-    if (ret != EOK) {
+    kerr = krb5_init_context(&context);
+    if (kerr != 0) {
+        DEBUG(SSSDBG_CRIT_FAILURE, ("Failed to init kerberos context\n"));
+        return EIO;
+    }
+
+    kerr = krb5_cc_resolve(context, location, &ccache);
+    if (kerr != 0) {
+        krb5_free_context(context);
+        DEBUG(SSSDBG_CRIT_FAILURE, ("krb5_cc_resolve failed.\n"));
+        return EIO;
+    }
+
+    kerr = check_for_valid_tgt(context, ccache, realm, princ, &valid);
+    krb5_free_context(context);
+    krb5_cc_close(context, ccache);
+    if (kerr != EOK) {
         DEBUG(SSSDBG_OP_FAILURE,
               ("Could not check if ccache contains a valid principal\n"));
-        return ret;
+        return EIO;
     }
 
     *_active = active;
@@ -735,3 +768,211 @@ struct sss_krb5_cc_be file_cc = {
     .ccache_for_princ   = cc_file_cache_for_princ,
     .remove             = cc_file_remove,
 };
+
+/*======== Operations on the DIR: back end ========*/
+errno_t
+cc_dir_create(const char *location, pcre *illegal_re,
+              uid_t uid, gid_t gid, bool private_path)
+{
+    const char *dirname;
+
+    dirname = sss_krb5_residual_check_type(location, SSS_KRB5_TYPE_DIR);
+    if (dirname == NULL) {
+        DEBUG(SSSDBG_CRIT_FAILURE, ("Bad residual type\n"));
+        return EINVAL;
+    }
+
+    return create_ccache_dir_head(dirname, illegal_re, uid, gid, private_path);
+}
+
+static krb5_error_code
+get_ccache_for_princ(krb5_context context, const char *location,
+                     const char *princ, krb5_ccache *_ccache)
+{
+    krb5_error_code krberr;
+    krb5_principal client_principal = NULL;
+
+    krberr = krb5_cc_set_default_name(context, location);
+    if (krberr != 0) {
+        DEBUG(SSSDBG_OP_FAILURE, ("krb5_cc_resolve failed.\n"));
+        return krberr;
+    }
+
+    krberr = krb5_parse_name(context, princ, &client_principal);
+    if (krberr != 0) {
+        DEBUG(SSSDBG_OP_FAILURE, ("krb5_parse_name failed.\n"));
+        return krberr;
+    }
+
+    krberr = krb5_cc_cache_match(context, client_principal, _ccache);
+    krb5_free_principal(context, client_principal);
+    return krberr;
+}
+
+errno_t
+cc_dir_check_existing(const char *location, uid_t uid,
+                      const char *realm, const char *princ,
+                      bool *_active, bool *_valid)
+{
+    bool active = false;
+    bool valid = false;
+    krb5_ccache ccache = NULL;
+    krb5_context context = NULL;
+    krb5_error_code krberr;
+    enum sss_krb5_cc_type type;
+    const char *filename;
+    const char *dir;
+    char *tmp;
+    errno_t ret;
+
+    type = sss_krb5_get_type(location);
+    if (type != SSS_KRB5_TYPE_DIR) {
+        DEBUG(SSSDBG_CRIT_FAILURE, ("%s is not of type DIR:\n", location));
+        return EINVAL;
+    }
+
+    filename = sss_krb5_cc_file_path(location);
+    if (!filename) {
+        DEBUG(SSSDBG_CRIT_FAILURE,
+              ("Existing ccname does not contain path into the collection"));
+        return EINVAL;
+    }
+
+    if (filename[0] != '/') {
+        DEBUG(SSSDBG_CRIT_FAILURE,
+              ("Only absolute path names are allowed.\n"));
+        return EINVAL;
+    }
+
+    tmp = talloc_strdup(NULL, filename);
+    if (!tmp) return ENOMEM;
+
+    dir = dirname(tmp);
+    if (!dir) {
+        DEBUG(SSSDBG_CRIT_FAILURE,
+              ("Cannot base get directory of %s\n", location));
+        return EINVAL;
+    }
+
+    ret = cc_residual_is_used(uid, dir, SSS_KRB5_TYPE_DIR, &active);
+    talloc_free(tmp);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_OP_FAILURE, ("Could not check if ccache is active\n"));
+        return ret;
+    }
+
+    krberr = krb5_init_context(&context);
+    if (krberr) {
+        DEBUG(SSSDBG_CRIT_FAILURE, ("Failed to init kerberos context\n"));
+        return EIO;
+    }
+
+    krberr = krb5_cc_resolve(context, location, &ccache);
+    if (krberr == KRB5_FCC_NOFILE || ccache == NULL) {
+        /* KRB5_FCC_NOFILE would be returned if the directory components
+         * of the DIR cache do not exist, which is the case in /run
+         * after a reboot
+         */
+        DEBUG(SSSDBG_TRACE_FUNC,
+              ("ccache %s is missing or empty\n", location));
+        valid = false;
+        ret = EOK;
+        goto done;
+    } else if (krberr != 0) {
+        KRB5_DEBUG(SSSDBG_OP_FAILURE, context, krberr);
+        DEBUG(SSSDBG_CRIT_FAILURE, ("krb5_cc_resolve failed.\n"));
+        ret = EIO;
+        goto done;
+    }
+
+    krberr = check_for_valid_tgt(context, ccache, realm, princ, &valid);
+    if (krberr != EOK) {
+        DEBUG(SSSDBG_CRIT_FAILURE,
+              ("Could not check if ccache contains a valid principal\n"));
+        ret = EIO;
+        goto done;
+    }
+
+    ret = EOK;
+done:
+    if (ccache) krb5_cc_close(context, ccache);
+    krb5_free_context(context);
+    *_active = active;
+    *_valid = valid;
+    return ret;
+}
+
+const char *
+cc_dir_cache_for_princ(TALLOC_CTX *mem_ctx, const char *location,
+                       const char *princ)
+{
+    krb5_context context = NULL;
+    krb5_error_code krberr;
+    krb5_ccache ccache = NULL;
+    char *name;
+    const char *ccname;
+
+    ccname = sss_krb5_residual_check_type(location, SSS_KRB5_TYPE_DIR);
+    if (!ccname) {
+        DEBUG(SSSDBG_CRIT_FAILURE, ("Cannot get ccname file from %s\n",
+              location));
+        return NULL;
+    }
+
+    /* ccname already points to a subsidiary cache */
+    if (ccname[0] == ':' && ccname[1] && ccname[1] == '/') {
+        return talloc_strdup(mem_ctx, location);
+    }
+
+    krberr = krb5_init_context(&context);
+    if (krberr) {
+        DEBUG(SSSDBG_OP_FAILURE, ("Failed to init kerberos context\n"));
+        return NULL;
+    }
+
+    krberr = get_ccache_for_princ(context, location, princ, &ccache);
+    if (krberr) {
+        DEBUG(SSSDBG_TRACE_FUNC, ("No principal for %s in %s\n",
+              princ, location));
+        krb5_free_context(context);
+        return NULL;
+    }
+
+    krberr = krb5_cc_get_full_name(context, ccache, &name);
+    if (ccache) krb5_cc_close(context, ccache);
+    krb5_free_context(context);
+    if (krberr) {
+        DEBUG(SSSDBG_TRACE_FUNC, ("Could not get full name of ccache\n"));
+        return NULL;
+    }
+
+    return talloc_strdup(mem_ctx, name);
+}
+
+errno_t
+cc_dir_remove(const char *location)
+{
+    const char *subsidiary;
+
+    if (sss_krb5_get_type(location) != SSS_KRB5_TYPE_DIR) {
+        DEBUG(SSSDBG_CRIT_FAILURE, ("%s is not of type DIR\n", location));
+        return EINVAL;
+    }
+
+    subsidiary = sss_krb5_cc_file_path(location);
+    if (!subsidiary) {
+        DEBUG(SSSDBG_CRIT_FAILURE, ("Cannot get subsidiary cache from %s\n",
+              location));
+        return EINVAL;
+    }
+
+    return cc_file_remove(subsidiary);
+}
+
+struct sss_krb5_cc_be dir_cc = {
+    .type               = SSS_KRB5_TYPE_DIR,
+    .create             = cc_dir_create,
+    .check_existing     = cc_dir_check_existing,
+    .ccache_for_princ   = cc_dir_cache_for_princ,
+    .remove             = cc_dir_remove
+};
diff --git a/src/providers/krb5/krb5_utils.h b/src/providers/krb5/krb5_utils.h
index 87bba2ba..5f677cae 100644
--- a/src/providers/krb5/krb5_utils.h
+++ b/src/providers/krb5/krb5_utils.h
@@ -53,10 +53,17 @@ struct sss_krb5_cc_be {
 };
 
 struct sss_krb5_cc_be file_cc;
+struct sss_krb5_cc_be dir_cc;
+
+errno_t create_ccache_dir(const char *dirname, pcre *illegal_re,
+                          uid_t uid, gid_t gid, bool private_path);
 
 errno_t cc_file_create(const char *filename, pcre *illegal_re,
                        uid_t uid, gid_t gid, bool private_path);
 
+errno_t cc_dir_create(const char *location, pcre *illegal_re,
+                      uid_t uid, gid_t gid, bool private_path);
+
 struct sss_krb5_cc_be *get_cc_be_ops(enum sss_krb5_cc_type type);
 struct sss_krb5_cc_be *get_cc_be_ops_ccache(const char *ccache);