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 <pwd.h>

20 #include <grp.h>

21

22 #include "masqmail.h"

23

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

25 gboolean

26 is_ingroup(uid_t uid, gid_t gid)

27 {

28 struct group *grent = getgrgid(gid);

29 struct passwd *pwent = getpwuid(uid);

30 char *entry;

31 int i = 0;

32

33 if (!grent) {

34 return FALSE;

35 }

36 if (!pwent) {

37 return FALSE;

38 }

39 /* check primary group */

40 if (pwent->pw_gid == gid) {

41 return TRUE;

42 }

43 /* check secondary groups */

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

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

46 return TRUE;

47 }

48 return FALSE;

49 }

50

51 gboolean

52 is_privileged_user(uid_t uid)

53 {

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

55 }

56

57 void

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

59 {

60 if (old_uid)

61 *old_uid = geteuid();

62 if (old_gid)

63 *old_gid = getegid();

64

65 seteuid(0);

66

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

68 logwrite(LOG_ALERT, "could not change gid to %d: %s\n", gid, strerror(errno));

69 exit(EXIT_FAILURE);

70 }

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

72 logwrite(LOG_ALERT, "could not change uid to %d: %s\n", uid, strerror(errno));

73 exit(EXIT_FAILURE);

74 }

75 }

76

77 void

78 set_identity(uid_t old_uid, gchar * task_name)

79 {

80 if (!conf.run_as_user) {

81 if (!is_privileged_user(old_uid)) {

82 fprintf(stderr, "must be root, %s or in group %s for %s.\n", DEF_MAIL_USER, DEF_MAIL_GROUP, task_name);

83 exit(EXIT_FAILURE);

84 }

85

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

87 }

88 }