execute_program.c

   1 #include "config.h"
   2
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <sys/types.h>
   6 #include <sys/stat.h>
   7 #include <unistd.h>
   8 #include <errno.h>
   9 #include <string.h>
  10 #include <pwd.h>
  11 #include <grp.h>
  12
  13 #include "common.h"
  14
  15 static void
  16 change_uid(Process *proc) {
  17         uid_t run_uid, run_euid;
  18         gid_t run_gid, run_egid;
  19
  20         if (options.user) {
  21                 struct passwd *pent;
  22
  23                 if (getuid() != 0 || geteuid() != 0) {
  24                         fprintf(stderr,
  25                                 "you must be root to use the -u option\n");
  26                         exit(1);
  27                 }
  28                 if ((pent = getpwnam(options.user)) == NULL) {
  29                         fprintf(stderr, "cannot find user `%s'\n", options.user);
  30                         exit(1);
  31                 }
  32                 run_uid = pent->pw_uid;
  33                 run_gid = pent->pw_gid;
  34
  35                 if (initgroups(options.user, run_gid) < 0) {
  36                         perror("ltrace: initgroups");
  37                         exit(1);
  38                 }
  39         } else {
  40                 run_uid = getuid();
  41                 run_gid = getgid();
  42         }
  43         if (options.user || !geteuid()) {
  44                 struct stat statbuf;
  45                 run_euid = run_uid;
  46                 run_egid = run_gid;
  47
  48                 if (!stat(proc->filename, &statbuf)) {
  49                         if (statbuf.st_mode & S_ISUID) {
  50                                 run_euid = statbuf.st_uid;
  51                         }
  52                         if (statbuf.st_mode & S_ISGID) {
  53                                 run_egid = statbuf.st_gid;
  54                         }
  55                 }
  56                 if (setregid(run_gid, run_egid) < 0) {
  57                         perror("ltrace: setregid");
  58                         exit(1);
  59                 }
  60                 if (setreuid(run_uid, run_euid) < 0) {
  61                         perror("ltrace: setreuid");
  62                         exit(1);
  63                 }
  64         }
  65 }
  66
  67 void
  68 execute_program(Process *sp, char **argv) {
  69         pid_t pid;
  70
  71         debug(1, "Executing `%s'...", sp->filename);
  72
  73         pid = fork();
  74         if (pid < 0) {
  75                 perror("ltrace: fork");
  76                 exit(1);
  77         } else if (!pid) {      /* child */
  78                 change_uid(sp);
  79                 trace_me();
  80                 execvp(sp->filename, argv);
  81                 fprintf(stderr, "Can't execute `%s': %s\n", sp->filename,
  82                         strerror(errno));
  83                 _exit(1);
  84         }
  85
  86         debug(1, "PID=%d", pid);
  87
  88         sp->pid = pid;
  89
  90         return;
  91 }