syscall.c

   1 /*
   2  * Functions for actually doing the system calls.
   3  */
   4
   5 #include <fcntl.h>
   6 #include <errno.h>
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <unistd.h>
  10 #include <sys/types.h>
  11 #include <sys/ptrace.h>
  12 #include <sys/syscall.h>
  13 #include <sys/wait.h>
  14
  15 #include "arch.h"
  16 #include "child.h"
  17 #include "random.h"
  18 #include "sanitise.h"
  19 #include "shm.h"
  20 #include "syscall.h"
  21 #include "pids.h"
  22 #include "log.h"
  23 #include "params.h"
  24 #include "maps.h"
  25 #include "tables.h"
  26 #include "trinity.h"
  27 #include "uid.h"
  28 #include "utils.h"
  29
  30 #define __syscall_return(type, res) \
  31         do { \
  32         if ((unsigned long)(res) >= (unsigned long)(-125)) { \
  33                 errno = -(res); \
  34                 res = -1; \
  35         } \
  36         return (type) (res); \
  37 } while (0)
  38
  39 #ifdef ARCH_IS_BIARCH
  40 /*
  41  * This routine does 32 bit syscalls on 64 bit kernel.
  42  * 32-on-32 will just use syscall() directly from do_syscall() because do32bit flag is biarch only.
  43  */
  44 static long syscall32(unsigned int call,
  45         unsigned long a1, unsigned long a2, unsigned long a3,
  46         unsigned long a4, unsigned long a5, unsigned long a6)
  47 {
  48         long __res = 0;
  49
  50 //FIXME: Move the implementations out to arch header files.
  51
  52 #if defined(__x86_64__)
  53         __asm__ volatile (
  54                 "pushq %%rbp\n\t"
  55                 "pushq %%r10\n\t"
  56                 "pushq %%r11\n\t"
  57                 "movq %7, %%rbp\n\t"
  58                 "int $0x80\n\t"
  59                 "popq %%r11\n\t"
  60                 "popq %%r10\n\t"
  61                 "popq %%rbp\n\t"
  62                 : "=a" (__res)
  63                 : "0" (call),"b" ((long)(a1)),"c" ((long)(a2)),"d" ((long)(a3)), "S" ((long)(a4)),"D" ((long)(a5)), "g" ((long)(a6))
  64                 : "%rbp" /* mark EBP reg as dirty */
  65         );
  66         __syscall_return(long, __res);
  67
  68 #else
  69         /* non-x86 implementations go here. */
  70         #error Implement 32-on-64 syscall in syscall.c:syscall32() for this architecture.
  71
  72 #endif
  73         return __res;
  74 }
  75 #else
  76 #define syscall32(a,b,c,d,e,f,g) 0
  77 #endif /* ARCH_IS_BIARCH */
  78
  79 static unsigned long do_syscall(int childno, int *errno_saved)
  80 {
  81         int nr = shm->syscall[childno].nr;
  82         unsigned long a1, a2, a3, a4, a5, a6;
  83         unsigned long ret = 0;
  84
  85         a1 = shm->syscall[childno].a1;
  86         a2 = shm->syscall[childno].a2;
  87         a3 = shm->syscall[childno].a3;
  88         a4 = shm->syscall[childno].a4;
  89         a5 = shm->syscall[childno].a5;
  90         a6 = shm->syscall[childno].a6;
  91
  92         shm->total_syscalls_done++;
  93         shm->child_syscall_count[childno]++;
  94         (void)gettimeofday(&shm->tv[childno], NULL);
  95
  96         if (syscalls[nr].entry->flags & NEED_ALARM)
  97                 (void)alarm(1);
  98
  99         errno = 0;
 100
 101         if (shm->syscall[childno].do32bit == FALSE)
 102                 ret = syscall(nr, a1, a2, a3, a4, a5, a6);
 103         else
 104                 ret = syscall32(nr, a1, a2, a3, a4, a5, a6);
 105
 106         *errno_saved = errno;
 107
 108         if (syscalls[nr].entry->flags & NEED_ALARM)
 109                 (void)alarm(0);
 110
 111         return ret;
 112 }
 113
 114 /*
 115  * Generate arguments, print them out, then call the syscall.
 116  *
 117  * returns a bool that determines whether we can keep doing syscalls
 118  * in this child.
 119  */
 120 bool mkcall(int childno)
 121 {
 122         struct syscallentry *entry;
 123         unsigned int call = shm->syscall[childno].nr;
 124         unsigned long ret = 0;
 125         int errno_saved;
 126
 127         entry = syscalls[call].entry;
 128
 129         shm->regenerate++;
 130
 131         shm->syscall[childno].a1 = (unsigned long) rand64();
 132         shm->syscall[childno].a2 = (unsigned long) rand64();
 133         shm->syscall[childno].a3 = (unsigned long) rand64();
 134         shm->syscall[childno].a4 = (unsigned long) rand64();
 135         shm->syscall[childno].a5 = (unsigned long) rand64();
 136         shm->syscall[childno].a6 = (unsigned long) rand64();
 137
 138         generic_sanitise(childno);
 139         if (entry->sanitise)
 140                 entry->sanitise(childno);
 141
 142         output_syscall_prefix(childno, call);
 143
 144         /* If we're going to pause, might as well sync pre-syscall */
 145         if (dopause == TRUE)
 146                 synclogs();
 147
 148         /* Some architectures (IA64/MIPS) start their Linux syscalls
 149          * At non-zero, and have other ABIs below.
 150          */
 151         call += SYSCALL_OFFSET;
 152
 153         /* This is a special case for things like execve, which would replace our
 154          * child process with something unknown to us. We use a 'throwaway' process
 155          * to do the execve in, and let it run for a max of a seconds before we kill it */
 156 #if 0
 157         if (syscalls[call].entry->flags & EXTRA_FORK) {
 158                 pid_t extrapid;
 159
 160                 extrapid = fork();
 161                 if (extrapid == 0) {
 162                         ret = do_syscall(childno, &errno_saved);
 163                         shm->syscall[childno].retval = ret;
 164                         _exit(EXIT_SUCCESS);
 165                 } else {
 166                         if (pid_alive(extrapid)) {
 167                                 sleep(1);
 168                                 kill(extrapid, SIGKILL);
 169                         }
 170                         return FALSE;
 171                 }
 172         }
 173 #endif
 174
 175         /* common-case, do the syscall in this child process. */
 176         ret = do_syscall(childno, &errno_saved);
 177         shm->syscall[childno].retval = ret;
 178
 179         if (IS_ERR(ret))
 180                 shm->failures++;
 181         else
 182                 shm->successes++;
 183
 184         output_syscall_postfix(ret, errno_saved, IS_ERR(ret));
 185         if (dopause == TRUE)
 186                 sleep(1);
 187
 188         /* If the syscall doesn't exist don't bother calling it next time. */
 189         if ((ret == -1UL) && (errno_saved == ENOSYS)) {
 190
 191                 /* Futex is awesome, it ENOSYS's depending on arguments. Sigh. */
 192                 if (call == (unsigned int) search_syscall_table(syscalls, max_nr_syscalls, "futex"))
 193                         goto skip_enosys;
 194
 195                 /* Unknown ioctls also ENOSYS. */
 196                 if (call == (unsigned int) search_syscall_table(syscalls, max_nr_syscalls, "ioctl"))
 197                         goto skip_enosys;
 198
 199                 /* sendfile() may ENOSYS depending on args. */
 200                 if (call == (unsigned int) search_syscall_table(syscalls, max_nr_syscalls, "sendfile"))
 201                         goto skip_enosys;
 202
 203                 output(1, "%s (%d) returned ENOSYS, marking as inactive.\n",
 204                         entry->name, call);
 205
 206                 if (biarch == FALSE) {
 207                         deactivate_syscall(call);
 208                 } else {
 209                         if (shm->syscall[childno].do32bit == TRUE)
 210                                 deactivate_syscall32(call);
 211                         else
 212                                 deactivate_syscall64(call);
 213                 }
 214         }
 215
 216 skip_enosys:
 217
 218         if (entry->post)
 219             entry->post(childno);
 220
 221         /* store info for debugging. */
 222         shm->previous[childno].nr = shm->syscall[childno].nr;
 223         shm->previous[childno].a1 = shm->syscall[childno].a1;
 224         shm->previous[childno].a2 = shm->syscall[childno].a2;
 225         shm->previous[childno].a3 = shm->syscall[childno].a3;
 226         shm->previous[childno].a4 = shm->syscall[childno].a4;
 227         shm->previous[childno].a5 = shm->syscall[childno].a5;
 228         shm->previous[childno].a6 = shm->syscall[childno].a6;
 229         shm->previous[childno].do32bit = shm->syscall[childno].do32bit;
 230
 231         check_uid();
 232
 233         return TRUE;
 234 }
 235
 236 bool this_syscallname(const char *thisname, int childno)
 237 {
 238         unsigned int call = shm->syscall[childno].nr;
 239         struct syscallentry *syscall_entry = syscalls[call].entry;
 240
 241         return strcmp(thisname, syscall_entry->name);
 242 }