1 files changed, 65 insertions, 5 deletions

diff --git a/usr.sbin/jexec/jexec.c b/usr.sbin/jexec/jexec.c
index 089a896..f35b1ec 100644
--- a/usr.sbin/jexec/jexec.c
+++ b/usr.sbin/jexec/jexec.c
@@ -30,26 +30,84 @@
 #include <sys/jail.h>
 
 #include <err.h>
+#include <errno.h>
+#include <login_cap.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <pwd.h>
 #include <unistd.h>
 
 static void	usage(void);
 
+#define GET_USER_INFO do {						\
+	pwd = getpwnam(username);					\
+	if (pwd == NULL) {						\
+		if (errno)						\
+			err(1, "getpwnam: %s", username);		\
+		else							\
+			errx(1, "%s: no such user", username);		\
+	}								\
+	lcap = login_getpwclass(pwd);					\
+	if (lcap == NULL)						\
+		err(1, "getpwclass: %s", username);			\
+	ngroups = NGROUPS;						\
+	if (getgrouplist(username, pwd->pw_gid, groups, &ngroups) != 0)	\
+		err(1, "getgrouplist: %s", username);			\
+} while (0)
+
 int
 main(int argc, char *argv[])
 {
 	int jid;
+	login_cap_t *lcap = NULL;
+	struct passwd *pwd = NULL;
+	gid_t groups[NGROUPS];
+	int ch, ngroups, uflag, Uflag;
+	char *username;
+	ch = uflag = Uflag = 0;
+	username = NULL;
 
-	if (argc < 3)
+	while ((ch = getopt(argc, argv, "u:U:")) != -1) {
+		switch (ch) {
+		case 'u':
+			username = optarg;
+			uflag = 1;
+			break;
+		case 'U':
+			username = optarg;
+			Uflag = 1;
+			break;
+		default:
+			usage();
+		}
+	}
+	argc -= optind;
+	argv += optind;
+	if (argc < 2)
+		usage();
+	if (uflag && Uflag)
 		usage();
-	jid = (int)strtol(argv[1], NULL, 10);
+	if (uflag)
+		GET_USER_INFO;
+	jid = (int)strtol(argv[0], NULL, 10);
 	if (jail_attach(jid) == -1)
 		err(1, "jail_attach(): %d", jid);
 	if (chdir("/") == -1)
 		err(1, "chdir(): /");
-	if (execvp(argv[2], argv + 2) == -1)
-		err(1, "execvp(): %s", argv[2]);
+	if (username != NULL) {
+		if (Uflag)
+			GET_USER_INFO;
+		if (setgroups(ngroups, groups) != 0)
+			err(1, "setgroups");
+		if (setgid(pwd->pw_gid) != 0)
+			err(1, "setgid");
+		if (setusercontext(lcap, pwd, pwd->pw_uid,
+		    LOGIN_SETALL & ~LOGIN_SETGROUP & ~LOGIN_SETLOGIN) != 0)
+			err(1, "setusercontext");
+		login_close(lcap);
+	}
+	if (execvp(argv[1], argv + 1) == -1)
+		err(1, "execvp(): %s", argv[1]);
 	exit(0);
 }
 
@@ -57,6 +115,8 @@ static void
 usage(void)
 {
 
-	fprintf(stderr, "usage: jexec jid command [...]\n");
+	fprintf(stderr, "%s%s\n",
+		"usage: jexec [-u username | -U username]",
+		" jid command [...]");
 	exit(1); 
 }