krb5: add copy_keytab_into_memory()

Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>

4 files changed, 427 insertions, 0 deletions

diff --git a/Makefile.am b/Makefile.am
index 54527223a..2cdba8ced 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -216,6 +216,7 @@ if HAVE_CMOCKA
         test_sysdb_views \
         test_be_ptask \
         test_copy_ccache \
+        test_copy_keytab \
         $(NULL)
 
 if BUILD_IFP
@@ -2114,6 +2115,23 @@ test_copy_ccache_LDADD = \
     libsss_test_common.la \
     $(NULL)
 
+test_copy_keytab_SOURCES = \
+    src/tests/cmocka/test_copy_keytab.c \
+    src/providers/krb5/krb5_keytab.c \
+    src/util/sss_krb5.c \
+    $(NULL)
+test_copy_keytab_CFLAGS = \
+    $(AM_CFLAGS) \
+    $(NULL)
+test_copy_keytab_LDADD = \
+    $(CMOCKA_LIBS) \
+    $(POPT_LIBS) \
+    $(TALLOC_LIBS) \
+    $(KRB5_LIBS) \
+    $(SSSD_INTERNAL_LTLIBS) \
+    libsss_test_common.la \
+    $(NULL)
+
 endif # HAVE_CMOCKA
 
 noinst_PROGRAMS = pam_test_client
diff --git a/src/providers/krb5/krb5_common.h b/src/providers/krb5/krb5_common.h
index a5cee6497..81e64688a 100644
--- a/src/providers/krb5/krb5_common.h
+++ b/src/providers/krb5/krb5_common.h
@@ -189,4 +189,35 @@ int sssm_krb5_auth_init(struct be_ctx *bectx,
                         struct bet_ops **ops,
                         void **pvt_auth_data);
 
+/* from krb5_keytab.c */
+
+/**
+ * @brief Copy given keytab into a MEMORY keytab
+ *
+ * @param[in] mem_ctx Talloc memory context the new keytab name should be
+ *                    allocated on
+ * @param[in] kctx Kerberos context
+ * @param[in] inp_keytab_file Existing keytab, if set to NULL the default
+ *                            keytab will be used
+ * @param[out] _mem_name Name of the new MEMORY keytab
+ * @param[out] _mem_keytab Krb5 keytab handle for the new MEMORY keytab, NULL
+ *                         may be passed here if the caller has no use for the
+ *                         handle
+ *
+ * The memory for the MEMORY keytab is handled by libkrb5 internally and
+ * a reference counter is used. If the reference counter of the specific
+ * MEMORY keytab reaches 0, i.e. no open ones are left, the memory is free.
+ * This means we cannot call krb5_kt_close() for the new MEMORY keytab  in
+ * copy_keytab_into_memory() because this would destroy it immediately. Hence
+ * we have to return the handle so that the caller can safely remove the
+ * MEMORY keytab if the is not needed anymore. Since libkrb5 frees the
+ * internal memory when the library is unloaded short running processes can
+ * safely pass NULL as the 5th argument because on exit all memory is freed.
+ * Long running processes which need more control over the memory consumption
+ * should close the handle for free the memory at runtime.
+ */
+krb5_error_code copy_keytab_into_memory(TALLOC_CTX *mem_ctx, krb5_context kctx,
+                                        const char *inp_keytab_file,
+                                        char **_mem_name,
+                                        krb5_keytab *_mem_keytab);
 #endif /* __KRB5_COMMON_H__ */
diff --git a/src/providers/krb5/krb5_keytab.c b/src/providers/krb5/krb5_keytab.c
new file mode 100644
index 000000000..855f69419
--- /dev/null
+++ b/src/providers/krb5/krb5_keytab.c
@@ -0,0 +1,165 @@
+/*
+    SSSD
+
+    Kerberos 5 Backend Module -- keytab related utilities
+
+    Authors:
+        Sumit Bose <sbose@redhat.com>
+
+    Copyright (C) 2014 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 "util/util.h"
+#include "util/sss_krb5.h"
+
+krb5_error_code copy_keytab_into_memory(TALLOC_CTX *mem_ctx, krb5_context kctx,
+                                        char *inp_keytab_file,
+                                        char **_mem_name,
+                                        krb5_keytab *_mem_keytab)
+{
+    krb5_error_code kerr;
+    krb5_error_code kt_err;
+    krb5_keytab keytab = NULL;
+    krb5_keytab mem_keytab = NULL;
+    krb5_kt_cursor cursor;
+    krb5_keytab_entry entry;
+    char keytab_name[MAX_KEYTAB_NAME_LEN];
+    char *sep;
+    char *mem_name = NULL;
+    char *keytab_file;
+    char default_keytab_name[MAX_KEYTAB_NAME_LEN];
+
+    keytab_file = inp_keytab_file;
+    if (keytab_file == NULL) {
+        kerr = krb5_kt_default_name(kctx, default_keytab_name,
+                                    sizeof(default_keytab_name));
+        if (kerr != 0) {
+            DEBUG(SSSDBG_CRIT_FAILURE, "krb5_kt_default_name failed.\n");
+            return kerr;
+        }
+
+        keytab_file = default_keytab_name;
+    }
+
+    kerr = krb5_kt_resolve(kctx, keytab_file, &keytab);
+    if (kerr != 0) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "error resolving keytab [%s].\n",
+                                    keytab_file);
+        return kerr;
+    }
+
+    kerr = krb5_kt_have_content(kctx, keytab);
+    if (kerr != 0) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "keytab [%s] has not entries.\n",
+                                    keytab_file);
+        goto done;
+    }
+
+    kerr = krb5_kt_get_name(kctx, keytab, keytab_name, sizeof(keytab_name));
+    if (kerr != 0) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "Failed to read name for keytab [%s].\n",
+                                    keytab_file);
+        goto done;
+    }
+
+    sep = strchr(keytab_name, ':');
+    if (sep == NULL || sep[1] == '\0') {
+        DEBUG(SSSDBG_CRIT_FAILURE,
+              "Keytab name [%s] does not have delimiter[:] .\n", keytab_name);
+        kerr = KRB5KRB_ERR_GENERIC;
+        goto done;
+    }
+
+    if (strncmp(keytab_name, "MEMORY:", sizeof("MEMORY:") -1) == 0) {
+        DEBUG(SSSDBG_TRACE_FUNC, "Keytab [%s] is already memory keytab.\n",
+                                 keytab_name);
+        *_mem_name = talloc_strdup(mem_ctx, keytab_name);
+        if(*_mem_name == NULL) {
+            DEBUG(SSSDBG_OP_FAILURE, "talloc_strdup failed.\n");
+            kerr = KRB5KRB_ERR_GENERIC;
+            goto done;
+        }
+        kerr = 0;
+        goto done;
+    }
+
+    mem_name = talloc_asprintf(mem_ctx, "MEMORY:%s", sep + 1);
+    if (mem_name == NULL) {
+        DEBUG(SSSDBG_OP_FAILURE, "talloc_asprintf failed.\n");
+        kerr = KRB5KRB_ERR_GENERIC;
+        goto done;
+    }
+
+    kerr = krb5_kt_resolve(kctx, mem_name, &mem_keytab);
+    if (kerr != 0) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "error resolving keytab [%s].\n",
+                                    mem_name);
+        goto done;
+    }
+
+    memset(&cursor, 0, sizeof(cursor));
+    kerr = krb5_kt_start_seq_get(kctx, keytab, &cursor);
+    if (kerr != 0) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "error reading keytab [%s].\n", keytab_file);
+        goto done;
+    }
+
+    memset(&entry, 0, sizeof(entry));
+    while ((kt_err = krb5_kt_next_entry(kctx, keytab, &entry, &cursor)) == 0) {
+        kerr = krb5_kt_add_entry(kctx, mem_keytab, &entry);
+        if (kerr != 0) {
+            DEBUG(SSSDBG_OP_FAILURE, "krb5_kt_add_entry failed.\n");
+            goto done;
+        }
+
+        kerr = sss_krb5_free_keytab_entry_contents(kctx, &entry);
+        if (kerr != 0) {
+            DEBUG(SSSDBG_MINOR_FAILURE, "Failed to free keytab entry.\n");
+        }
+        memset(&entry, 0, sizeof(entry));
+    }
+
+    kerr = krb5_kt_end_seq_get(kctx, keytab, &cursor);
+    if (kerr != 0) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "krb5_kt_end_seq_get failed.\n");
+        goto done;
+    }
+
+    /* check if we got any errors from krb5_kt_next_entry */
+    if (kt_err != 0 && kt_err != KRB5_KT_END) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "error reading keytab [%s].\n", keytab_file);
+        kerr = KRB5KRB_ERR_GENERIC;
+        goto done;
+    }
+
+    *_mem_name = mem_name;
+    if (_mem_keytab != NULL) {
+        *_mem_keytab = mem_keytab;
+    }
+
+    kerr = 0;
+done:
+
+    if (kerr != 0) {
+        talloc_free(mem_name);
+    }
+
+    if (keytab != NULL && krb5_kt_close(kctx, keytab) != 0) {
+            DEBUG(SSSDBG_MINOR_FAILURE, "krb5_kt_close failed");
+    }
+
+    return kerr;
+}
diff --git a/src/tests/cmocka/test_copy_keytab.c b/src/tests/cmocka/test_copy_keytab.c
new file mode 100644
index 000000000..9d2b80156
--- /dev/null
+++ b/src/tests/cmocka/test_copy_keytab.c
@@ -0,0 +1,213 @@
+/*
+    Authors:
+        Sumit Bose <sbose@redhat.com>
+
+    Copyright (C) 2014 Red Hat
+
+    SSSD tests: Tests keytab utilities
+
+    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 <stdio.h>
+#include <popt.h>
+
+#include "util/sss_krb5.h"
+#include "providers/krb5/krb5_common.h"
+#include "tests/cmocka/common_mock.h"
+
+#define KEYTAB_TEST_PRINC "test/keytab@TEST.KEYTAB"
+#define KEYTAB_PATH TEST_DIR "/keytab_test.keytab"
+
+struct keytab_test_ctx {
+    krb5_context kctx;
+    const char *keytab_file_name;
+    krb5_principal principal;
+};
+
+void setup_keytab(void **state)
+{
+    struct keytab_test_ctx *test_ctx;
+    krb5_error_code kerr;
+    krb5_keytab keytab;
+    krb5_keytab_entry kent;
+
+    assert_true(leak_check_setup());
+
+    test_ctx = talloc_zero(global_talloc_context, struct keytab_test_ctx);
+    assert_non_null(test_ctx);
+
+    kerr = krb5_init_context(&test_ctx->kctx);
+    assert_int_equal(kerr, 0);
+
+    test_ctx->keytab_file_name = "FILE:" KEYTAB_PATH;
+
+    kerr = krb5_kt_resolve(test_ctx->kctx, test_ctx->keytab_file_name, &keytab);
+    assert_int_equal(kerr, 0);
+
+    kerr = krb5_parse_name(test_ctx->kctx, KEYTAB_TEST_PRINC,
+                           &test_ctx->principal);
+    assert_int_equal(kerr, 0);
+
+    memset(&kent, 0, sizeof(kent));
+    kent.magic = KV5M_KEYTAB_ENTRY;
+    kent.principal = test_ctx->principal;
+    kent.timestamp = 12345;
+    kent.vno = 1;
+    kent.key.magic = KV5M_KEYBLOCK;
+    kent.key.enctype = 1;
+    kent.key.length = 2;
+    kent.key.contents = (krb5_octet *) discard_const("11");
+
+    kerr = krb5_kt_add_entry(test_ctx->kctx, keytab, &kent);
+    assert_int_equal(kerr, 0);
+
+    kent.key.enctype = 2;
+    kent.key.contents = (krb5_octet *) discard_const("12");
+
+    kerr = krb5_kt_add_entry(test_ctx->kctx, keytab, &kent);
+    assert_int_equal(kerr, 0);
+
+    kent.vno = 2;
+    kent.key.enctype = 1;
+    kent.key.contents = (krb5_octet *) discard_const("21");
+
+    kerr = krb5_kt_add_entry(test_ctx->kctx, keytab, &kent);
+    assert_int_equal(kerr, 0);
+
+    kent.key.enctype = 2;
+    kent.key.contents = (krb5_octet *) discard_const("22");
+
+    kerr = krb5_kt_add_entry(test_ctx->kctx, keytab, &kent);
+    assert_int_equal(kerr, 0);
+
+    kerr = krb5_kt_close(test_ctx->kctx, keytab);
+    assert_int_equal(kerr, 0);
+
+    check_leaks_push(test_ctx);
+    *state = test_ctx;
+}
+
+void teardown_keytab(void **state)
+{
+    int ret;
+    struct keytab_test_ctx *test_ctx = talloc_get_type(*state,
+                                                        struct keytab_test_ctx);
+    assert_non_null(test_ctx);
+
+    krb5_free_principal(test_ctx->kctx, test_ctx->principal);
+    krb5_free_context(test_ctx->kctx);
+
+    ret = unlink(KEYTAB_PATH);
+    assert_int_equal(ret, 0);
+
+    assert_true(check_leaks_pop(test_ctx) == true);
+    talloc_free(test_ctx);
+    assert_true(leak_check_teardown());
+}
+
+void test_copy_keytab(void **state)
+{
+    krb5_error_code kerr;
+    char *mem_keytab_name;
+    krb5_keytab mem_keytab;
+    krb5_keytab keytab;
+    krb5_keytab_entry kent;
+    struct keytab_test_ctx *test_ctx = talloc_get_type(*state,
+                                                        struct keytab_test_ctx);
+    assert_non_null(test_ctx);
+
+    kerr = copy_keytab_into_memory(test_ctx, test_ctx->kctx,
+                                   test_ctx->keytab_file_name,
+                                   &mem_keytab_name, &mem_keytab);
+    assert_int_equal(kerr, 0);
+    assert_non_null(mem_keytab_name);
+
+    kerr = krb5_kt_resolve(test_ctx->kctx, mem_keytab_name, &keytab);
+    assert_int_equal(kerr, 0);
+
+    kerr = krb5_kt_get_entry(test_ctx->kctx, keytab, test_ctx->principal, 9, 9,
+                             &kent);
+    assert_int_not_equal(kerr, 0);
+
+    kerr = krb5_kt_get_entry(test_ctx->kctx, keytab, test_ctx->principal, 1, 1,
+                             &kent);
+    assert_int_equal(kerr, 0);
+    krb5_free_keytab_entry_contents(test_ctx->kctx, &kent);
+
+    kerr = krb5_kt_get_entry(test_ctx->kctx, keytab, test_ctx->principal, 1, 2,
+                             &kent);
+    assert_int_equal(kerr, 0);
+    krb5_free_keytab_entry_contents(test_ctx->kctx, &kent);
+
+    kerr = krb5_kt_get_entry(test_ctx->kctx, keytab, test_ctx->principal, 2, 1,
+                             &kent);
+    assert_int_equal(kerr, 0);
+    krb5_free_keytab_entry_contents(test_ctx->kctx, &kent);
+
+    kerr = krb5_kt_get_entry(test_ctx->kctx, keytab, test_ctx->principal, 2, 2,
+                             &kent);
+    assert_int_equal(kerr, 0);
+    krb5_free_keytab_entry_contents(test_ctx->kctx, &kent);
+
+    talloc_free(mem_keytab_name);
+
+    kerr = krb5_kt_close(test_ctx->kctx, keytab);
+    assert_int_equal(kerr, 0);
+
+    kerr = krb5_kt_close(test_ctx->kctx, mem_keytab);
+    assert_int_equal(kerr, 0);
+}
+
+int main(int argc, const char *argv[])
+{
+    poptContext pc;
+    int opt;
+    int rv;
+    struct poptOption long_options[] = {
+        POPT_AUTOHELP
+        SSSD_DEBUG_OPTS
+        POPT_TABLEEND
+    };
+
+    const UnitTest tests[] = {
+        unit_test_setup_teardown(test_copy_keytab,
+                                 setup_keytab, teardown_keytab),
+    };
+
+    /* Set debug level to invalid value so we can deside if -d 0 was used. */
+    debug_level = SSSDBG_INVALID;
+
+    pc = poptGetContext(argv[0], argc, argv, long_options, 0);
+    while((opt = poptGetNextOpt(pc)) != -1) {
+        switch(opt) {
+        default:
+            fprintf(stderr, "\nInvalid option %s: %s\n\n",
+                    poptBadOption(pc, 0), poptStrerror(opt));
+            poptPrintUsage(pc, stderr, 0);
+            return 1;
+        }
+    }
+    poptFreeContext(pc);
+
+    DEBUG_CLI_INIT(debug_level);
+
+    /* Even though normally the tests should clean up after themselves
+     * they might not after a failed run. Remove the old db to be sure */
+    tests_set_cwd();
+
+    rv = run_tests(tests);
+
+    return rv;
+}