servers/ipc/utility.c

   1 #include "inc.h"
   2
   3 int check_perm(struct ipc_perm *req, endpoint_t who, int mode)
   4 {
   5         int req_mode;
   6         int cur_mode;
   7         uid_t uid = getnuid(who);
   8         gid_t gid = getngid(who);
   9
  10         mode &= 0666;
  11
  12         /* is root? */
  13         if (uid == 0)
  14                 return 1;
  15
  16         if (uid == req->uid || uid == req->cuid) {
  17                 /* same user */
  18                 req_mode = (req->mode >> 6) & 0x7;
  19                 cur_mode = (mode >> 6) & 0x7;
  20         } else if (gid == req->gid || gid == req->cgid) {
  21                 /* same group */
  22                 req_mode = (req->mode >> 3) & 0x7;
  23                 cur_mode = (mode >> 3) & 0x7;
  24         } else {
  25                 /* other group */
  26                 req_mode = req->mode & 0x7;
  27                 cur_mode = mode & 0x7;
  28         }
  29
  30         if (cur_mode && ((cur_mode & req_mode) == cur_mode))
  31                 return 1;
  32         else
  33                 return 0;
  34 }
  35