From 60295a63fadf04f6cd6db7919aa1dad6fb4f0596 Mon Sep 17 00:00:00 2001
From: Nalin Dahyabhai <nalin@dahyabhai.net>
Date: Wed, 30 Oct 2013 21:45:35 -0400
Subject: [PATCH 2/6] Use an in-memory cache until we need the target's
Instead of copying source or obtained creds into the target cache and
changing ownership if everything succeeds, copy them into a MEMORY:
cache and then, if everything succeeds, create the target cache as the
target user.
---
src/clients/ksu/ksu.h | 1 +
src/clients/ksu/main.c | 133 +++++++++++++++++++++++++++++--------------------
2 files changed, 80 insertions(+), 54 deletions(-)
diff --git a/src/clients/ksu/ksu.h b/src/clients/ksu/ksu.h
index 2a63c21..1d102a1 100644
--- a/src/clients/ksu/ksu.h
+++ b/src/clients/ksu/ksu.h
@@ -45,6 +45,7 @@
#define KRB5_DEFAULT_TKT_LIFE 60*60*12 /* 12 hours */
#define KRB5_SECONDARY_CACHE "FILE:/tmp/krb5cc_"
+#define KRB5_TEMPORARY_CACHE "MEMORY:_ksu"
#define KRB5_LOGIN_NAME ".k5login"
#define KRB5_USERS_NAME ".k5users"
diff --git a/src/clients/ksu/main.c b/src/clients/ksu/main.c
index e2ca06a..fa86c78 100644
--- a/src/clients/ksu/main.c
+++ b/src/clients/ksu/main.c
@@ -86,7 +86,7 @@ main (argc, argv)
int statusp=0;
krb5_error_code retval = 0;
krb5_principal client = NULL;
- krb5_ccache cc_target = NULL;
+ krb5_ccache cc_tmp = NULL, cc_target = NULL;
krb5_context ksu_context;
char * cc_target_tag = NULL;
char * target_user = NULL;
@@ -452,14 +452,15 @@ main (argc, argv)
}
/*
- Only when proper authentication and authorization
- takes place, the target user becomes the owner of the cache.
- */
-
- /* we continue to run as source uid until
- the middle of the copy, when becomewe become the target user
- The cache is owned by the target user.*/
+ * Only after proper authentication and authorization has
+ * taken place, do we populate a cache for the target user.
+ */
+ /*
+ * We read the set of creds we want to copy from the source ccache as the
+ * source uid, become root for authentication, and then become the target
+ * user to handle authorization and creating the target user's cache.
+ */
/* if root ksu's to a regular user, then
then only the credentials for that particular user
@@ -468,19 +469,23 @@ main (argc, argv)
if ((source_uid == 0) && (target_uid != 0)) {
if ((retval = krb5_ccache_copy_restricted(ksu_context, cc_source,
- cc_target_tag, client,
- &cc_target, &stored,
- target_uid))){
+ KRB5_TEMPORARY_CACHE, client,
+ &cc_tmp, &stored,
+ 0))){
com_err(prog_name, retval, _("while copying cache %s to %s"),
- krb5_cc_get_name(ksu_context, cc_source), cc_target_tag);
+ krb5_cc_get_name(ksu_context, cc_source),
+ KRB5_TEMPORARY_CACHE);
exit(1);
}
} else {
- if ((retval = krb5_ccache_copy(ksu_context, cc_source, cc_target_tag,
- client,&cc_target, &stored, target_uid))) {
+
+ retval = krb5_ccache_copy(ksu_context, cc_source, KRB5_TEMPORARY_CACHE,
+ client, &cc_tmp, &stored, 0);
+ if (retval) {
com_err(prog_name, retval, _("while copying cache %s to %s"),
- krb5_cc_get_name(ksu_context, cc_source), cc_target_tag);
+ krb5_cc_get_name(ksu_context, cc_source),
+ KRB5_TEMPORARY_CACHE);
exit(1);
}
@@ -502,7 +507,7 @@ main (argc, argv)
&kdc_server))){
com_err(prog_name, retval,
_("while creating tgt for local realm"));
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
@@ -510,13 +515,13 @@ main (argc, argv)
"enter it here and are logged\n"));
fprintf(stderr, _(" in remotely using an unsecure "
"(non-encrypted) channel.\n"));
- if (krb5_get_tkt_via_passwd (ksu_context, &cc_target, client,
- kdc_server, &options,
- &zero_password) == FALSE){
+ if (krb5_get_tkt_via_passwd(ksu_context, &cc_tmp, client,
+ kdc_server, &options,
+ &zero_password) == FALSE){
if (zero_password == FALSE){
fprintf(stderr, _("Goodbye\n"));
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
@@ -535,15 +540,16 @@ main (argc, argv)
if (source_uid && (source_uid != target_uid)) {
char * client_name;
- auth_val = krb5_auth_check(ksu_context, client, localhostname, &options,
- target_user,cc_target, &path_passwd, target_uid);
+ auth_val = krb5_auth_check(ksu_context, client, localhostname,
+ &options, target_user, cc_tmp,
+ &path_passwd, target_uid);
/* if Kerberos authentication failed then exit */
if (auth_val ==FALSE){
fprintf(stderr, _("Authentication failed.\n"));
syslog(LOG_WARNING, "'%s %s' authentication failed for %s%s",
prog_name,target_user,source_user,ontty());
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
@@ -576,7 +582,7 @@ main (argc, argv)
if ((retval = krb5_unparse_name(ksu_context, client, &client_name))) {
com_err(prog_name, retval, _("When unparsing name"));
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
@@ -589,7 +595,7 @@ main (argc, argv)
if (krb5_seteuid(target_uid)) {
com_err(prog_name, errno, _("while switching to target for "
"authorization check"));
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
@@ -597,14 +603,14 @@ main (argc, argv)
cmd, &authorization_val, &exec_cmd))){
com_err(prog_name,retval, _("while checking authorization"));
krb5_seteuid(0); /*So we have some chance of sweeping up*/
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
if (krb5_seteuid(0)) {
com_err(prog_name, errno, _("while switching back from target "
"after authorization check"));
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
if (authorization_val == TRUE){
@@ -646,21 +652,23 @@ main (argc, argv)
}
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
}
if( some_rest_copy){
- if ((retval = krb5_ccache_filter(ksu_context, cc_target, client))){
+ retval = krb5_ccache_filter(ksu_context, cc_tmp, client);
+ if (retval) {
com_err(prog_name,retval, _("while calling cc_filter"));
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
}
if (all_rest_copy){
- if ((retval = krb5_cc_initialize(ksu_context, cc_target, client))){
+ retval = krb5_cc_initialize(ksu_context, cc_tmp, client);
+ if (retval) {
com_err(prog_name, retval, _("while erasing target cache"));
exit(1);
}
@@ -682,7 +690,7 @@ main (argc, argv)
if (!standard_shell(target_pwd->pw_shell) && source_uid) {
fprintf(stderr, _("ksu: permission denied (shell).\n"));
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
#endif /* HAVE_GETUSERSHELL */
@@ -692,43 +700,33 @@ main (argc, argv)
if(set_env_var("USER", target_pwd->pw_name)){
fprintf(stderr,
_("ksu: couldn't set environment variable USER\n"));
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
}
if(set_env_var( "HOME", target_pwd->pw_dir)){
fprintf(stderr, _("ksu: couldn't set environment variable HOME\n"));
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
if(set_env_var( "SHELL", shell)){
fprintf(stderr, _("ksu: couldn't set environment variable SHELL\n"));
- sweep_up(ksu_context, cc_target);
- exit(1);
- }
-
- /* set the cc env name to target */
-
- if(set_env_var( KRB5_ENV_CCNAME, cc_target_tag)){
- fprintf(stderr, _("ksu: couldn't set environment variable %s\n"),
- KRB5_ENV_CCNAME);
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
/* set permissions */
if (setgid(target_pwd->pw_gid) < 0) {
perror("ksu: setgid");
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
-
if (initgroups(target_user, target_pwd->pw_gid)) {
fprintf(stderr, _("ksu: initgroups failed.\n"));
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
@@ -748,22 +746,49 @@ main (argc, argv)
*/
if (setluid((uid_t) pwd->pw_uid) < 0) {
perror("setluid");
- sweep_up(ksu_context, cc_target);
+ sweep_up(ksu_context, cc_tmp);
exit(1);
}
#endif /* HAVE_SETLUID */
- if (setuid(target_pwd->pw_uid) < 0) {
+ if (seteuid(0) < 0 || seteuid(target_pwd->pw_uid) < 0) {
+ perror("ksu: seteuid");
+ sweep_up(ksu_context, cc_tmp);
+ exit(1);
+ }
+
+ retval = krb5_ccache_copy(ksu_context, cc_tmp, cc_target_tag,
+ client, &cc_target, &stored,
+ target_pwd->pw_uid);
+ if (retval) {
+ com_err(prog_name, retval, _("while copying cache %s to %s"),
+ krb5_cc_get_name(ksu_context, cc_tmp), cc_target_tag);
+ exit(1);
+ }
+
+ if (setuid(0) < 0 || setuid(target_pwd->pw_uid) < 0) {
perror("ksu: setuid");
sweep_up(ksu_context, cc_target);
exit(1);
}
- if (access( cc_target_tag_tmp, R_OK | W_OK )){
- com_err(prog_name, errno,
- _("%s does not have correct permissions for %s, %s aborted"),
- target_user, cc_target_tag_tmp, prog_name);
- exit(1);
+ /* set the cc env name to target */
+ if (stored) {
+ if (krb5_cc_get_full_name(ksu_context, cc_target,
+ &cc_target_tag) == 0) {
+ if (set_env_var(KRB5_ENV_CCNAME, cc_target_tag)){
+ fprintf(stderr,
+ _("ksu: couldn't set environment variable %s\n"),
+ KRB5_ENV_CCNAME);
+ sweep_up(ksu_context, cc_target);
+ exit(1);
+ }
+ krb5_free_string(ksu_context, cc_target_tag);
+ } else {
+ com_err(prog_name, retval, _("while reading cache name from %s"),
+ cc_target_tag);
+ exit(1);
+ }
}
if ( cc_source)
--
1.8.4.2