util-linux/setpriv.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * setpriv implementation for busybox based on linux-utils-ng 2.29
   4  *
   5  * Copyright (C) 2017 by  <assafgordon@gmail.com>
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  *
   9  */
  10 //config:config SETPRIV
  11 //config:       bool "setpriv"
  12 //config:       default y
  13 //config:       select PLATFORM_LINUX
  14 //config:       select LONG_OPTS
  15 //config:       help
  16 //config:         Run a program with different Linux privilege settings.
  17 //config:         Requires kernel >= 3.5
  18 //config:
  19 //config:config FEATURE_SETPRIV_DUMP
  20 //config:       bool "Support dumping current privilege state"
  21 //config:       default y
  22 //config:       depends on SETPRIV
  23 //config:       help
  24 //config:         Enables the "--dump" switch to print out the current privilege
  25 //config:         state. This is helpful for diagnosing problems.
  26
  27 //applet:IF_SETPRIV(APPLET(setpriv, BB_DIR_BIN, BB_SUID_DROP))
  28
  29 //kbuild:lib-$(CONFIG_SETPRIV) += setpriv.o
  30
  31 //usage:#define setpriv_trivial_usage
  32 //usage:        "[OPTIONS] PROG [ARGS]"
  33 //usage:#define setpriv_full_usage "\n\n"
  34 //usage:       "Run PROG with different privilege settings\n"
  35 //usage:        IF_FEATURE_SETPRIV_DUMP(
  36 //usage:     "\n-d,--dump               Show current capabilities"
  37 //usage:        )
  38 //usage:     "\n--nnp,--no-new-privs    Ignore setuid/setgid bits and file capabilities"
  39
  40 //setpriv from util-linux 2.28:
  41 // -d, --dump               show current state (and do not exec anything)
  42 // --nnp, --no-new-privs    disallow granting new privileges
  43 // --inh-caps <caps,...>    set inheritable capabilities
  44 // --bounding-set <caps>    set capability bounding set
  45 // --ruid <uid>             set real uid
  46 // --euid <uid>             set effective uid
  47 // --rgid <gid>             set real gid
  48 // --egid <gid>             set effective gid
  49 // --reuid <uid>            set real and effective uid
  50 // --regid <gid>            set real and effective gid
  51 // --clear-groups           clear supplementary groups
  52 // --keep-groups            keep supplementary groups
  53 // --groups <group,...>     set supplementary groups
  54 // --securebits <bits>      set securebits
  55 // --selinux-label <label>  set SELinux label
  56 // --apparmor-profile <pr>  set AppArmor profile
  57
  58 #include <sys/prctl.h>
  59 #include "libbb.h"
  60
  61 #ifndef PR_SET_NO_NEW_PRIVS
  62 #define PR_SET_NO_NEW_PRIVS 38
  63 #endif
  64
  65 #ifndef PR_GET_NO_NEW_PRIVS
  66 #define PR_GET_NO_NEW_PRIVS 39
  67 #endif
  68
  69 enum {
  70         IF_FEATURE_SETPRIV_DUMP(OPTBIT_DUMP,)
  71         OPTBIT_NNP,
  72
  73         IF_FEATURE_SETPRIV_DUMP(OPT_DUMP = (1 << OPTBIT_DUMP),)
  74         OPT_NNP  = (1 << OPTBIT_NNP),
  75 };
  76
  77 #if ENABLE_FEATURE_SETPRIV_DUMP
  78 static int dump(void)
  79 {
  80         uid_t ruid, euid, suid;
  81         gid_t rgid, egid, sgid;
  82         gid_t *gids;
  83         int ngids, nnp;
  84
  85         getresuid(&ruid, &euid, &suid); /* never fails in Linux */
  86         getresgid(&rgid, &egid, &sgid); /* never fails in Linux */
  87         ngids = 0;
  88         gids = bb_getgroups(&ngids, NULL); /* never fails in Linux */
  89
  90         nnp = prctl(PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0);
  91         if (nnp < 0)
  92                 bb_simple_perror_msg_and_die("prctl: GET_NO_NEW_PRIVS");
  93
  94         printf("uid: %u\n", (unsigned)ruid);
  95         printf("euid: %u\n", (unsigned)euid);
  96         printf("gid: %u\n", (unsigned)rgid);
  97         printf("egid: %u\n", (unsigned)egid);
  98
  99         printf("Supplementary groups: ");
 100         if (ngids == 0) {
 101                 printf("[none]");
 102         } else {
 103                 const char *fmt = ",%u" + 1;
 104                 int i;
 105                 for (i = 0; i < ngids; i++) {
 106                         printf(fmt, (unsigned)gids[i]);
 107                         fmt = ",%u";
 108                 }
 109         }
 110         printf("\nno_new_privs: %d\n", nnp);
 111
 112         if (ENABLE_FEATURE_CLEAN_UP)
 113                 free(gids);
 114         return EXIT_SUCCESS;
 115 }
 116 #endif /* FEATURE_SETPRIV_DUMP */
 117
 118 int setpriv_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 119 int setpriv_main(int argc UNUSED_PARAM, char **argv)
 120 {
 121         static const char setpriv_longopts[] ALIGN1 =
 122                 IF_FEATURE_SETPRIV_DUMP(
 123                 "dump\0"         No_argument    "d"
 124                 )
 125                 "nnp\0"          No_argument    "\xff"
 126                 "no-new-privs\0" No_argument    "\xff"
 127                 ;
 128         int opts;
 129
 130         applet_long_options = setpriv_longopts;
 131         opts = getopt32(argv, "+"IF_FEATURE_SETPRIV_DUMP("d"));
 132         argv += optind;
 133
 134 #if ENABLE_FEATURE_SETPRIV_DUMP
 135         if (opts & OPT_DUMP) {
 136                 if (argv[0] || (opts - OPT_DUMP) != 0)
 137                         bb_show_usage();
 138                 return dump();
 139         }
 140 #endif
 141         if (opts & OPT_NNP) {
 142                 if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0))
 143                         bb_simple_perror_msg_and_die("prctl: NO_NEW_PRIVS");
 144         }
 145
 146         if (!argv[0])
 147                 bb_show_usage();
 148         BB_EXECVP_or_die(argv);
 149 }