src/test/test-capability.c

   1 /***
   2   This file is part of systemd
   3
   4   Copyright 2014 Ronny Chevalier
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <netinet/in.h>
  21 #include <pwd.h>
  22 #include <sys/capability.h>
  23 #include <sys/socket.h>
  24 #include <sys/wait.h>
  25 #include <unistd.h>
  26
  27 #include "capability.h"
  28 #include "fd-util.h"
  29 #include "macro.h"
  30 #include "util.h"
  31
  32 static uid_t test_uid = -1;
  33 static gid_t test_gid = -1;
  34
  35 /* We keep CAP_DAC_OVERRIDE to avoid errors with gcov when doing test coverage */
  36 static uint64_t test_flags = 1ULL << CAP_DAC_OVERRIDE;
  37
  38 static void fork_test(void (*test_func)(void)) {
  39         pid_t pid = 0;
  40
  41         pid = fork();
  42         assert_se(pid >= 0);
  43         if (pid == 0) {
  44                 test_func();
  45                 exit(0);
  46         } else if (pid > 0) {
  47                 int status;
  48
  49                 assert_se(waitpid(pid, &status, 0) > 0);
  50                 assert_se(WIFEXITED(status) && WEXITSTATUS(status) == 0);
  51         }
  52 }
  53
  54 static void show_capabilities(void) {
  55         cap_t caps;
  56         char *text;
  57
  58         caps = cap_get_proc();
  59         assert_se(caps);
  60
  61         text = cap_to_text(caps, NULL);
  62         assert_se(text);
  63
  64         log_info("Capabilities:%s", text);
  65         cap_free(caps);
  66         cap_free(text);
  67 }
  68
  69 static int setup_tests(void) {
  70         struct passwd *nobody;
  71
  72         nobody = getpwnam("nobody");
  73         if (!nobody) {
  74                 log_error_errno(errno, "Could not find nobody user: %m");
  75                 return -EXIT_TEST_SKIP;
  76         }
  77         test_uid = nobody->pw_uid;
  78         test_gid = nobody->pw_gid;
  79
  80         return 0;
  81 }
  82
  83 static void test_drop_privileges_keep_net_raw(void) {
  84         int sock;
  85
  86         sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
  87         assert_se(sock >= 0);
  88         safe_close(sock);
  89
  90         assert_se(drop_privileges(test_uid, test_gid, test_flags | (1ULL << CAP_NET_RAW)) >= 0);
  91         assert_se(getuid() == test_uid);
  92         assert_se(getgid() == test_gid);
  93         show_capabilities();
  94
  95         sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
  96         assert_se(sock >= 0);
  97         safe_close(sock);
  98 }
  99
 100 static void test_drop_privileges_dontkeep_net_raw(void) {
 101         int sock;
 102
 103         sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
 104         assert_se(sock >= 0);
 105         safe_close(sock);
 106
 107         assert_se(drop_privileges(test_uid, test_gid, test_flags) >= 0);
 108         assert_se(getuid() == test_uid);
 109         assert_se(getgid() == test_gid);
 110         show_capabilities();
 111
 112         sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
 113         assert_se(sock < 0);
 114 }
 115
 116 static void test_drop_privileges_fail(void) {
 117         assert_se(drop_privileges(test_uid, test_gid, test_flags) >= 0);
 118         assert_se(getuid() == test_uid);
 119         assert_se(getgid() == test_gid);
 120
 121         assert_se(drop_privileges(test_uid, test_gid, test_flags) < 0);
 122         assert_se(drop_privileges(0, 0, test_flags) < 0);
 123 }
 124
 125 static void test_drop_privileges(void) {
 126         fork_test(test_drop_privileges_keep_net_raw);
 127         fork_test(test_drop_privileges_dontkeep_net_raw);
 128         fork_test(test_drop_privileges_fail);
 129 }
 130
 131 static void test_have_effective_cap(void) {
 132         assert_se(have_effective_cap(CAP_KILL));
 133         assert_se(have_effective_cap(CAP_CHOWN));
 134
 135         assert_se(drop_privileges(test_uid, test_gid, test_flags | (1ULL << CAP_KILL)) >= 0);
 136         assert_se(getuid() == test_uid);
 137         assert_se(getgid() == test_gid);
 138
 139         assert_se(have_effective_cap(CAP_KILL));
 140         assert_se(!have_effective_cap(CAP_CHOWN));
 141 }
 142
 143 int main(int argc, char *argv[]) {
 144         int r;
 145
 146         log_parse_environment();
 147         log_open();
 148
 149         if (getuid() != 0)
 150                 return EXIT_TEST_SKIP;
 151
 152         r = setup_tests();
 153         if (r < 0)
 154                 return -r;
 155
 156         show_capabilities();
 157
 158         test_drop_privileges();
 159         fork_test(test_have_effective_cap);
 160
 161         return 0;
 162 }