1 files changed, 62 insertions, 3 deletions

diff --git a/util-linux/setpriv.c b/util-linux/setpriv.c
index d15e0d8..f21ce66 100644
--- a/util-linux/setpriv.c
+++ b/util-linux/setpriv.c
@@ -15,6 +15,14 @@
 //config:	help
 //config:	  Run a program with different Linux privilege settings.
 //config:	  Requires kernel >= 3.5
+//config:
+//config:config FEATURE_SETPRIV_DUMP
+//config:	bool "Support dumping current privilege state"
+//config:	default y
+//config:	depends on SETPRIV
+//config:	help
+//config:	  Enables the "--dump" switch to print out the current privilege
+//config:	  state. This is helpful for diagnosing problems.
 
 //applet:IF_SETPRIV(APPLET(setpriv, BB_DIR_BIN, BB_SUID_DROP))
 
@@ -24,6 +32,9 @@
 //usage:	"[OPTIONS] PROG [ARGS]"
 //usage:#define setpriv_full_usage "\n\n"
 //usage:       "Run PROG with different privilege settings\n"
+//usage:	IF_FEATURE_SETPRIV_DUMP(
+//usage:     "\n-d,--dump		Show current capabilities"
+//usage:	)
 //usage:     "\n--nnp,--no-new-privs	Ignore setuid/setgid bits and file capabilities"
 
 //setpriv from util-linux 2.28:
@@ -52,25 +63,73 @@
 #endif
 
 enum {
+	IF_FEATURE_SETPRIV_DUMP(OPTBIT_DUMP,)
 	OPTBIT_NNP,
 
-	OPT_NNP = (1 << OPTBIT_NNP),
+	IF_FEATURE_SETPRIV_DUMP(OPT_DUMP = (1 << OPTBIT_DUMP),)
+	OPT_NNP  = (1 << OPTBIT_NNP),
 };
 
+#if ENABLE_FEATURE_SETPRIV_DUMP
+static int dump(void)
+{
+	uid_t ruid, euid, suid;
+	gid_t rgid, egid, sgid;
+	gid_t *gids;
+	int ngids;
+
+	getresuid(&ruid, &euid, &suid); /* never fails in Linux */
+	getresgid(&rgid, &egid, &sgid); /* never fails in Linux */
+	ngids = 0;
+	gids = bb_getgroups(&ngids, NULL); /* never fails in Linux */
+
+	printf("uid: %u\n", (unsigned)ruid);
+	printf("euid: %u\n", (unsigned)euid);
+	printf("gid: %u\n", (unsigned)rgid);
+	printf("egid: %u\n", (unsigned)egid);
+
+	printf("Supplementary groups: ");
+	if (ngids == 0) {
+		printf("[none]");
+	} else {
+		const char *fmt = ",%u" + 1;
+		int i;
+		for (i = 0; i < ngids; i++) {
+			printf(fmt, (unsigned)gids[i]);
+			fmt = ",%u";
+		}
+	}
+	bb_putchar('\n');
+
+	if (ENABLE_FEATURE_CLEAN_UP)
+		free(gids);
+	return EXIT_SUCCESS;
+}
+#endif /* FEATURE_SETPRIV_DUMP */
+
 int setpriv_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int setpriv_main(int argc UNUSED_PARAM, char **argv)
 {
 	static const char setpriv_longopts[] ALIGN1 =
+		IF_FEATURE_SETPRIV_DUMP(
+		"dump\0"         No_argument	"d"
+		)
 		"nnp\0"          No_argument	"\xff"
 		"no-new-privs\0" No_argument	"\xff"
 		;
 	int opts;
 
 	applet_long_options = setpriv_longopts;
-	opts = getopt32(argv, "+");
-
+	opts = getopt32(argv, "+"IF_FEATURE_SETPRIV_DUMP("d"));
 	argv += optind;
 
+#if ENABLE_FEATURE_SETPRIV_DUMP
+	if (opts & OPT_DUMP) {
+		if (argv[0] || (opts - OPT_DUMP) != 0)
+			bb_show_usage();
+		return dump();
+	}
+#endif
 	if (opts & OPT_NNP) {
 		if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0))
 			bb_simple_perror_msg_and_die("prctl: NO_NEW_PRIVS");