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change_identity.c 2.3 KB

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  1. /* vi: set sw=4 ts=4: */
  2. /*
  3. * Copyright 1989 - 1991, Julianne Frances Haugh <jockgrrl@austin.rr.com>
  4. * All rights reserved.
  5. *
  6. * Redistribution and use in source and binary forms, with or without
  7. * modification, are permitted provided that the following conditions
  8. * are met:
  9. * 1. Redistributions of source code must retain the above copyright
  10. * notice, this list of conditions and the following disclaimer.
  11. * 2. Redistributions in binary form must reproduce the above copyright
  12. * notice, this list of conditions and the following disclaimer in the
  13. * documentation and/or other materials provided with the distribution.
  14. * 3. Neither the name of Julianne F. Haugh nor the names of its contributors
  15. * may be used to endorse or promote products derived from this software
  16. * without specific prior written permission.
  17. *
  18. * THIS SOFTWARE IS PROVIDED BY JULIE HAUGH AND CONTRIBUTORS ''AS IS'' AND
  19. * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21. * ARE DISCLAIMED. IN NO EVENT SHALL JULIE HAUGH OR CONTRIBUTORS BE LIABLE
  22. * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23. * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24. * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27. * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28. * SUCH DAMAGE.
  29. */
  30. #include "libbb.h"
  31. /* Become the user and group(s) specified by PW. */
  32. void FAST_FUNC change_identity(const struct passwd *pw)
  33. {
  34. int res;
  35. res = initgroups(pw->pw_name, pw->pw_gid);
  36. endgrent(); /* helps to close a fd used internally by libc */
  37. if (res != 0) {
  38. /*
  39. * If initgroups() fails because a system call is unimplemented
  40. * then we are running on a Linux kernel compiled without multiuser
  41. * support (CONFIG_MULTIUSER is not defined).
  42. *
  43. * If we are running without multiuser support *and* the target uid
  44. * already matches the current uid then we can skip the change of
  45. * identity.
  46. */
  47. if (errno == ENOSYS && pw->pw_uid == getuid()) {
  48. return;
  49. }
  50. bb_perror_msg_and_die("can't set groups");
  51. }
  52. xsetgid(pw->pw_gid);
  53. xsetuid(pw->pw_uid);
  54. }