syscalls/execve.c

   1 /*
   2  * SYSCALL_DEFINE3(execve,
   3  *                const char __user *, filename,
   4  *                const char __user *const __user *, argv,
   5  *                const char __user *const __user *, envp)
   6  *
   7  * On success, execve() does not return
   8  * on error -1 is returned, and errno is set appropriately.
   9  *
  10  * TODO: Redirect stdin/stdout.
  11  */
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include "arch.h"       // page_size
  15 #include "random.h"     // generate_random_page
  16 #include "sanitise.h"
  17 #include "shm.h"
  18 #include "trinity.h"    // __unused__
  19
  20 static unsigned long ** gen_ptrs_to_crap(void)
  21 {
  22         void **ptr;
  23         unsigned int i;
  24         unsigned int count = rand() % 32;
  25
  26         /* Fabricate argv */
  27         ptr = malloc(count * sizeof(void *));   // FIXME: LEAK
  28         if (ptr == NULL)
  29                 return NULL;
  30
  31         for (i = 0; i < count; i++) {
  32                 ptr[i] = malloc(page_size);     // FIXME: LEAK
  33                 if (ptr[i] != NULL)
  34                         generate_random_page((char *) ptr[i]);
  35         }
  36
  37         return (unsigned long **) ptr;
  38 }
  39
  40 static void sanitise_execve(__unused__ int childno)
  41 {
  42         /* we don't want to block if something tries to read from stdin */
  43         fclose(stdin);
  44
  45         /* Fabricate argv */
  46         shm->syscall[childno].a2 = (unsigned long) gen_ptrs_to_crap();
  47
  48         /* Fabricate envp */
  49         shm->syscall[childno].a3 = (unsigned long) gen_ptrs_to_crap();
  50 }
  51
  52 struct syscallentry syscall_execve = {
  53         .name = "execve",
  54         .num_args = 3,
  55         .arg1name = "name",
  56         .arg1type = ARG_PATHNAME,
  57         .arg2name = "argv",
  58         .arg2type = ARG_ADDRESS,
  59         .arg3name = "envp",
  60         .arg3type = ARG_ADDRESS,
  61         .sanitise = sanitise_execve,
  62         .group = GROUP_VFS,
  63         .flags = EXTRA_FORK,
  64 };