1 /* MasqMail

2 Copyright (C) 2000 Oliver Kurth

3

4 This program is free software; you can redistribute it and/or modify

5 it under the terms of the GNU General Public License as published by

6 the Free Software Foundation; either version 2 of the License, or

7 (at your option) any later version.

8

9 This program is distributed in the hope that it will be useful,

10 but WITHOUT ANY WARRANTY; without even the implied warranty of

11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

12 GNU General Public License for more details.

13

14 You should have received a copy of the GNU General Public License

15 along with this program; if not, write to the Free Software

16 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

17 */

18

19 #include "masqmail.h"

20 #include <pwd.h>

21 #include <grp.h>

22

23 /* is there really no function in libc for this? */

24 gboolean is_ingroup(uid_t uid, gid_t gid)

25 {

26 struct group *grent = getgrgid(gid);

27

28 if(grent){

29 struct passwd *pwent = getpwuid(uid);

30 if(pwent){

31 char *entry;

32 int i = 0;

33 while((entry = grent->gr_mem[i++])){

34 if(strcmp(pwent->pw_name, entry) == 0)

35 return TRUE;

36 }

37 }

38 }

39 return FALSE;

40 }

41

42 gboolean is_privileged_user(uid_t uid)

43 {

44 return (uid == 0) || (uid == conf.mail_uid) || (is_ingroup(uid, conf.mail_gid));

45 }

46

47 void set_euidgid(gint uid, gint gid, uid_t *old_uid, gid_t *old_gid)

48 {

49 if(old_uid) *old_uid = geteuid();

50 if(old_gid) *old_gid = getegid();

51

52 seteuid(0);

53

54 if(setegid(gid) != 0){

55 logwrite(LOG_ALERT, "could not change gid to %d: %s\n",

56 gid, strerror(errno));

57 exit(EXIT_FAILURE);

58 }

59 if(seteuid(uid) != 0){

60 logwrite(LOG_ALERT, "could not change uid to %d: %s\n",

61 uid, strerror(errno));

62 exit(EXIT_FAILURE);

63 }

64 }

65

66 void set_identity(uid_t old_uid, gchar *task_name)

67 {

68 if(!conf.run_as_user){

69 if(!is_privileged_user(old_uid)){

70 fprintf(stderr,

71 "must be root, %s or in group %s for %s.\n",

72 DEF_MAIL_USER, DEF_MAIL_GROUP, task_name);

73 exit(EXIT_FAILURE);

74 }

75

76 set_euidgid(conf.mail_uid, conf.mail_gid, NULL, NULL);

77 }

78 }