child.c

   1 /*
   2  * Each process that gets forked runs this code.
   3  */
   4
   5 #include <fcntl.h>
   6 #include <errno.h>
   7 #include <signal.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <unistd.h>
  11 #include <sched.h>
  12 #include <sys/time.h>
  13 #include <sys/resource.h>
  14 #include <sys/prctl.h>
  15
  16 #include "arch.h"
  17 #include "child.h"
  18 #include "list.h"
  19 #include "log.h"
  20 #include "maps.h"
  21 #include "params.h"     // for 'debug'
  22 #include "pids.h"
  23 #include "random.h"
  24 #include "shm.h"
  25 #include "signals.h"
  26 #include "syscall.h"
  27 #include "tables.h"
  28 #include "trinity.h"    // ARRAY_SIZE
  29 #include "utils.h"      // zmalloc
  30
  31 static struct rlimit oldrlimit;
  32
  33 static void disable_coredumps(void)
  34 {
  35         struct rlimit limit;
  36
  37         if (debug == TRUE) {
  38                 (void)signal(SIGABRT, SIG_DFL);
  39                 (void)signal(SIGSEGV, SIG_DFL);
  40                 return;
  41         }
  42
  43         getrlimit(RLIMIT_CORE, &oldrlimit);
  44
  45         limit.rlim_cur = 0;
  46         limit.rlim_max = oldrlimit.rlim_max;
  47         if (setrlimit(RLIMIT_CORE, &limit) != 0)
  48                 perror( "setrlimit(RLIMIT_CORE)" );
  49 }
  50
  51 static void reenable_coredumps(void)
  52 {
  53         if (debug == TRUE)
  54                 return;
  55
  56         prctl(PR_SET_DUMPABLE, TRUE);
  57
  58         if (setrlimit(RLIMIT_CORE, &oldrlimit) != 0) {
  59                 outputerr("[%d] Error restoring rlimits to cur:%d max:%d (%s)\n",
  60                         getpid(),
  61                         (unsigned int) oldrlimit.rlim_cur,
  62                         (unsigned int) oldrlimit.rlim_max,
  63                         strerror(errno));
  64         }
  65 }
  66 static void set_make_it_fail(void)
  67 {
  68         int fd;
  69         const char *buf = "1";
  70
  71         /* If we failed last time, don't bother trying in future. */
  72         if (shm->do_make_it_fail == TRUE)
  73                 return;
  74
  75         fd = open("/proc/self/make-it-fail", O_WRONLY);
  76         if (fd == -1)
  77                 return;
  78
  79         if (write(fd, buf, 1) == -1) {
  80                 if (errno != EPERM)
  81                         outputerr("writing to /proc/self/make-it-fail failed! (%s)\n", strerror(errno));
  82                 else
  83                         shm->do_make_it_fail = TRUE;
  84         }
  85         close(fd);
  86 }
  87
  88 /*
  89  * We call this occasionally to set some FPU state, in the hopes that we
  90  * might tickle some weird FPU/scheduler related bugs
  91  */
  92 static void use_fpu(void)
  93 {
  94         double x = 0;
  95         asm volatile("":"+m" (x));
  96         x += 1;
  97         asm volatile("":"+m" (x));
  98 }
  99
 100 int this_child = 0;
 101
 102 static void setup_page_maps(void)
 103 {
 104         unsigned long *page;
 105         unsigned int i;
 106
 107         page = (void *) page_maps;
 108
 109         for (i = 0; i < page_size / sizeof(unsigned long); i++) {
 110                 struct map *map;
 111
 112                 map = get_map();
 113                 page[i] = (unsigned long) map->ptr;
 114         }
 115 }
 116
 117 void init_child(int childno)
 118 {
 119         cpu_set_t set;
 120         pid_t pid = getpid();
 121
 122         this_child = childno;
 123
 124         set_seed(childno);
 125
 126         shm->kill_count[childno] = 0;
 127
 128         disable_coredumps();
 129
 130         setup_page_maps();
 131
 132         if (sched_getaffinity(pid, sizeof(set), &set) == 0) {
 133                 CPU_ZERO(&set);
 134                 CPU_SET(childno, &set);
 135                 sched_setaffinity(pid, sizeof(set), &set);
 136         }
 137
 138         shm->child_syscall_count[childno] = 0;
 139
 140         set_make_it_fail();
 141
 142         if (rand() % 100 < 50)
 143                 use_fpu();
 144
 145         shm->num_mappings[childno] = 0;
 146         shm->mappings[childno] = zmalloc(sizeof(struct map));
 147         INIT_LIST_HEAD(&shm->mappings[childno]->list);
 148 }
 149
 150 void check_parent_pid(void)
 151 {
 152         pid_t pid;
 153         unsigned int i;
 154         static unsigned int parent_check_time = 10;
 155
 156         parent_check_time--;
 157         if (parent_check_time != 0)
 158                 return;
 159
 160         parent_check_time = 10;
 161
 162         if (getppid() == shm->mainpid)
 163                 return;
 164
 165         pid = getpid();
 166
 167         //FIXME: Add locking so only one child does this output.
 168         output(0, BUGTXT "CHILD (pid:%d) GOT REPARENTED! "
 169                 "parent pid:%d. Watchdog pid:%d\n",
 170                 pid, shm->mainpid, watchdog_pid);
 171         output(0, BUGTXT "Last syscalls:\n");
 172
 173         for (i = 0; i < shm->running_childs; i++) {
 174                 // Skip over 'boring' entries.
 175                 if ((shm->pids[i] == EMPTY_PIDSLOT) &&
 176                     (shm->previous_syscallno[i] == 0) &&
 177                     (shm->child_syscall_count[i] == 0))
 178                         continue;
 179
 180                 output(0, "[%d]  pid:%d call:%s callno:%d\n",
 181                         i, shm->pids[i],
 182                         print_syscall_name(shm->previous_syscallno[i], shm->do32bit[i]),        // FIXME: need previous do32bit
 183                         shm->child_syscall_count[i]);
 184         }
 185         shm->exit_reason = EXIT_REPARENT_PROBLEM;
 186         exit(EXIT_FAILURE);
 187         //TODO: Emergency logging.
 188 }
 189
 190 struct child_funcs {
 191         int type;
 192         const char *name;
 193         int (*func)(int childno);
 194 };
 195
 196 static const struct child_funcs child_functions[] = {
 197         { .type = CHILD_RANDOM_SYSCALLS, .name = "rand_syscalls", .func = child_random_syscalls },
 198 #ifdef DEBUG_MULTI
 199         { .type = CHILD_OPEN_ALL_FILES, .name = "read_all_files", .func = child_read_all_files },
 200 #endif
 201 };
 202
 203 int child_process(int childno)
 204 {
 205         int ret;
 206         unsigned int i;
 207
 208         i = rand() % ARRAY_SIZE(child_functions);
 209
 210 #ifdef DEBUG_MULTI
 211         output(0, "Chose %s.\n", child_functions[i].name);
 212 #endif
 213
 214         shm->child_type[childno] = child_functions[i].type;
 215         ret = child_functions[i].func(childno);
 216
 217         reenable_coredumps();
 218
 219         return ret;
 220 }