From: Tomas Mraz <tmraz@fedoraproject.org>
Date: Mon, 7 Mar 2011 13:27:46 +0000 (+0100)
Subject: Set only groups in the process handling PAM calls. Keep uids at 0
X-Git-Tag: cronie1.4.7~16
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4d8294bcf025b0467c6fdc1943a9008e280d38c5;p=cronie

Set only groups in the process handling PAM calls. Keep uids at 0
so the process is not killable by the user.
---

diff --git a/src/do_command.c b/src/do_command.c
index 1a80f48..e664d4c 100644
--- a/src/do_command.c
+++ b/src/do_command.c
@@ -166,9 +166,6 @@ static int child_process(entry * e, user * u, char **jobenv) {
 	case 0:
 		Debug(DPROC, ("[%ld] grandchild process fork()'ed\n", (long) getpid()))
 
-		if (cron_change_user_permanently(e->pwd, env_get("HOME", jobenv)) < 0)
-			_exit(ERROR_EXIT);
-		
 		/* write a log message.  we've waited this long to do it
 		 * because it was not until now that we knew the PID that
 		 * the actual user command shell was going to get and the
@@ -181,9 +178,8 @@ static int child_process(entry * e, user * u, char **jobenv) {
 			free(x);
 		}
 
-		/* that's the last thing we'll log.  close the log files.
-		 */
-		log_close();
+		if (cron_change_user_permanently(e->pwd, env_get("HOME", jobenv)) < 0)
+			_exit(ERROR_EXIT);
 
 		/* get new pgrp, void tty, etc.
 		 */
@@ -414,12 +410,11 @@ static int child_process(entry * e, user * u, char **jobenv) {
 				gethostname(hostname, MAXHOSTNAMELEN);
 
 				if (MailCmd[0] == '\0') {
-					if (strlens(MAILFMT, MAILARG, mailfrom, NULL) + 1
+					if (snprintf(mailcmd, sizeof mailcmd, MAILFMT, MAILARG, mailfrom)
 						>= sizeof mailcmd) {
 						fprintf(stderr, "mailcmd too long\n");
 						(void) _exit(ERROR_EXIT);
 					}
-					(void) sprintf(mailcmd, MAILFMT, MAILARG, mailfrom);
 				}
 				else {
 					strncpy(mailcmd, MailCmd, MAX_COMMAND);
diff --git a/src/funcs.h b/src/funcs.h
index fabd0b2..f0e576e 100644
--- a/src/funcs.h
+++ b/src/funcs.h
@@ -93,7 +93,7 @@ int cron_open_security_session( struct passwd *pw );
 
 void cron_close_security_session( void );
 
-int cron_change_user( struct passwd *pw );
+int cron_change_groups( struct passwd *pw );
 
 int cron_change_user_permanently( struct passwd *pw, char *homedir );
 
diff --git a/src/popen.c b/src/popen.c
index 48afbb2..baf0724 100644
--- a/src/popen.c
+++ b/src/popen.c
@@ -108,6 +108,9 @@ FILE *cron_popen(char *program, const char *type, struct passwd *pw) {
 		sa.sa_handler = SIG_DFL;
 		sigaction(SIGPIPE, &sa, NULL);
 
+		if (cron_change_user_permanently(pw, pw->pw_dir) != 0)
+			_exit(2);
+
 		if (execvp(argv[0], argv) < 0) {
 			int save_errno = errno;
 
diff --git a/src/security.c b/src/security.c
index 6f6ff39..5816205 100644
--- a/src/security.c
+++ b/src/security.c
@@ -142,13 +142,10 @@ int cron_set_job_security_context(entry * e, user * u, char ***jobenv) {
 	}
 #endif
 
-	if (cron_change_user(e->pwd) != 0) {
-		log_it(e->pwd->pw_name, getpid(), "ERROR", "failed to change user", 0);
+	if (cron_change_groups(e->pwd) != 0) {
 		return -1;
 	}
 
-	log_close();
-
 	time_t job_run_time = time(0L);
 
 	if ((minutely_time > 0) && ((job_run_time / 60) != (minutely_time / 60))) {
@@ -211,11 +208,9 @@ void cron_close_pam(void) {
 #endif
 }
 
-int cron_change_user(struct passwd *pw) {
+int cron_change_groups(struct passwd *pw) {
 	pid_t pid = getpid();
-	/* set our directory, uid and gid.  Set gid first, since once
-	 * we set uid, we've lost root privledges.
-	 */
+
 	if (setgid(pw->pw_gid) != 0) {
 		log_it("CRON", pid, "ERROR", "setgid failed", errno);
 		return -1;
@@ -226,10 +221,11 @@ int cron_change_user(struct passwd *pw) {
 		return -1;
 	}
 
-	if (setreuid(pw->pw_uid, -1) != 0) {
-		log_it("CRON", pid, "ERROR", "setreuid failed", errno);
-		return -1;
-	}
+#if defined(WITH_PAM)
+	/* credentials may take form of supplementary groups so reinitialize
+	 * them here */
+	pam_setcred(pamh, PAM_REINITIALIZE_CRED | PAM_SILENT);
+#endif
 
 	return 0;
 }
@@ -239,11 +235,14 @@ int cron_change_user_permanently(struct passwd *pw, char *homedir) {
 		log_it("CRON", getpid(), "ERROR", "setreuid failed", errno);
 		return -1;
 	}
+
 	if (chdir(homedir) == -1) {
 		log_it("CRON", getpid(), "ERROR chdir failed", homedir, errno);
 		return -1;
 	}
 
+	log_close();
+
 	return 0;
 }