tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /*
   4  * Based on Christian Brauner's clone3() example.
   5  * These tests are assuming to be running in the host's
   6  * PID namespace.
   7  */
   8
   9 /* capabilities related code based on selftests/bpf/test_verifier.c */
  10
  11 #define _GNU_SOURCE
  12 #include <errno.h>
  13 #include <linux/types.h>
  14 #include <linux/sched.h>
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <stdbool.h>
  18 #include <sys/capability.h>
  19 #include <sys/prctl.h>
  20 #include <sys/syscall.h>
  21 #include <sys/types.h>
  22 #include <sys/un.h>
  23 #include <sys/wait.h>
  24 #include <unistd.h>
  25 #include <sched.h>
  26
  27 #include "../kselftest_harness.h"
  28 #include "clone3_selftests.h"
  29
  30 static void child_exit(int ret)
  31 {
  32         fflush(stdout);
  33         fflush(stderr);
  34         _exit(ret);
  35 }
  36
  37 static int call_clone3_set_tid(struct __test_metadata *_metadata,
  38                                pid_t *set_tid, size_t set_tid_size)
  39 {
  40         int status;
  41         pid_t pid = -1;
  42
  43         struct __clone_args args = {
  44                 .exit_signal = SIGCHLD,
  45                 .set_tid = ptr_to_u64(set_tid),
  46                 .set_tid_size = set_tid_size,
  47         };
  48
  49         pid = sys_clone3(&args, sizeof(args));
  50         if (pid < 0) {
  51                 TH_LOG("%s - Failed to create new process", strerror(errno));
  52                 return -errno;
  53         }
  54
  55         if (pid == 0) {
  56                 int ret;
  57                 char tmp = 0;
  58
  59                 TH_LOG("I am the child, my PID is %d (expected %d)", getpid(), set_tid[0]);
  60
  61                 if (set_tid[0] != getpid())
  62                         child_exit(EXIT_FAILURE);
  63                 child_exit(EXIT_SUCCESS);
  64         }
  65
  66         TH_LOG("I am the parent (%d). My child's pid is %d", getpid(), pid);
  67
  68         if (waitpid(pid, &status, 0) < 0) {
  69                 TH_LOG("Child returned %s", strerror(errno));
  70                 return -errno;
  71         }
  72
  73         if (!WIFEXITED(status))
  74                 return -1;
  75
  76         return WEXITSTATUS(status);
  77 }
  78
  79 static int test_clone3_set_tid(struct __test_metadata *_metadata,
  80                                pid_t *set_tid, size_t set_tid_size)
  81 {
  82         int ret;
  83
  84         TH_LOG("[%d] Trying clone3() with CLONE_SET_TID to %d", getpid(), set_tid[0]);
  85         ret = call_clone3_set_tid(_metadata, set_tid, set_tid_size);
  86         TH_LOG("[%d] clone3() with CLONE_SET_TID %d says:%d", getpid(), set_tid[0], ret);
  87         return ret;
  88 }
  89
  90 struct libcap {
  91         struct __user_cap_header_struct hdr;
  92         struct __user_cap_data_struct data[2];
  93 };
  94
  95 static int set_capability(void)
  96 {
  97         cap_value_t cap_values[] = { CAP_SETUID, CAP_SETGID };
  98         struct libcap *cap;
  99         int ret = -1;
 100         cap_t caps;
 101
 102         caps = cap_get_proc();
 103         if (!caps) {
 104                 perror("cap_get_proc");
 105                 return -1;
 106         }
 107
 108         /* Drop all capabilities */
 109         if (cap_clear(caps)) {
 110                 perror("cap_clear");
 111                 goto out;
 112         }
 113
 114         cap_set_flag(caps, CAP_EFFECTIVE, 2, cap_values, CAP_SET);
 115         cap_set_flag(caps, CAP_PERMITTED, 2, cap_values, CAP_SET);
 116
 117         cap = (struct libcap *) caps;
 118
 119         /* 40 -> CAP_CHECKPOINT_RESTORE */
 120         cap->data[1].effective |= 1 << (40 - 32);
 121         cap->data[1].permitted |= 1 << (40 - 32);
 122
 123         if (cap_set_proc(caps)) {
 124                 perror("cap_set_proc");
 125                 goto out;
 126         }
 127         ret = 0;
 128 out:
 129         if (cap_free(caps))
 130                 perror("cap_free");
 131         return ret;
 132 }
 133
 134 TEST(clone3_cap_checkpoint_restore)
 135 {
 136         pid_t pid;
 137         int status;
 138         int ret = 0;
 139         pid_t set_tid[1];
 140
 141         test_clone3_supported();
 142
 143         EXPECT_EQ(getuid(), 0)
 144                 SKIP(return, "Skipping all tests as non-root");
 145
 146         memset(&set_tid, 0, sizeof(set_tid));
 147
 148         /* Find the current active PID */
 149         pid = fork();
 150         if (pid == 0) {
 151                 TH_LOG("Child has PID %d", getpid());
 152                 child_exit(EXIT_SUCCESS);
 153         }
 154         ASSERT_GT(waitpid(pid, &status, 0), 0)
 155                 TH_LOG("Waiting for child %d failed", pid);
 156
 157         /* After the child has finished, its PID should be free. */
 158         set_tid[0] = pid;
 159
 160         ASSERT_EQ(set_capability(), 0)
 161                 TH_LOG("Could not set CAP_CHECKPOINT_RESTORE");
 162
 163         ASSERT_EQ(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0), 0);
 164
 165         EXPECT_EQ(setgid(65534), 0)
 166                 TH_LOG("Failed to setgid(65534)");
 167         ASSERT_EQ(setuid(65534), 0);
 168
 169         set_tid[0] = pid;
 170         /* This would fail without CAP_CHECKPOINT_RESTORE */
 171         ASSERT_EQ(test_clone3_set_tid(_metadata, set_tid, 1), -EPERM);
 172         ASSERT_EQ(set_capability(), 0)
 173                 TH_LOG("Could not set CAP_CHECKPOINT_RESTORE");
 174         /* This should work as we have CAP_CHECKPOINT_RESTORE as non-root */
 175         ASSERT_EQ(test_clone3_set_tid(_metadata, set_tid, 1), 0);
 176 }
 177
 178 TEST_HARNESS_MAIN