1 files changed, 62 insertions, 3 deletions

diff --git a/util-linux/setpriv.c b/util-linux/setpriv.c
index d15e0d84e..f21ce6632 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");