1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) The Exim Maintainers 2022 - 2023 */
6 /* SPDX-License-Identifier: GPL-2.0-or-later */
14 PRIV_DROPPING, PRIV_DROPPED,
15 PRIV_RESTORING, PRIV_RESTORED
16 } priv_state = PRIV_RESTORED;
19 static uid_t priv_euid;
20 static gid_t priv_egid;
21 static gid_t priv_groups[EXIM_GROUPLIST_SIZE + 1];
22 static int priv_ngroups;
24 /* Inspired by OpenSSH's temporarily_use_uid(). Thanks! */
27 priv_drop_temp(const uid_t temp_uid, const gid_t temp_gid)
29 if (priv_state != PRIV_RESTORED)
30 log_write(0, LOG_PANIC_DIE, "priv_drop_temp: unexpected priv_state %d != %d", priv_state, PRIV_RESTORED);
32 priv_state = PRIV_DROPPING;
34 priv_euid = geteuid();
35 if (priv_euid == root_uid)
37 priv_egid = getegid();
38 priv_ngroups = getgroups(nelem(priv_groups), priv_groups);
40 log_write(0, LOG_PANIC_DIE, "getgroups: %s", strerror(errno));
42 if (priv_ngroups > 0 && setgroups(1, &temp_gid) != 0)
43 log_write(0, LOG_PANIC_DIE, "setgroups: %s", strerror(errno));
44 if (setegid(temp_gid) != 0)
45 log_write(0, LOG_PANIC_DIE, "setegid(%d): %s", temp_gid, strerror(errno));
46 if (seteuid(temp_uid) != 0)
47 log_write(0, LOG_PANIC_DIE, "seteuid(%d): %s", temp_uid, strerror(errno));
49 if (geteuid() != temp_uid)
50 log_write(0, LOG_PANIC_DIE, "getdeuid() != %d", temp_uid);
51 if (getegid() != temp_gid)
52 log_write(0, LOG_PANIC_DIE, "getegid() != %d", temp_gid);
55 priv_state = PRIV_DROPPED;
58 /* Inspired by OpenSSH's restore_uid(). Thanks! */
63 if (priv_state != PRIV_DROPPED)
64 log_write(0, LOG_PANIC_DIE, "priv_restore: unexpected priv_state %d != %d", priv_state, PRIV_DROPPED);
65 priv_state = PRIV_RESTORING;
67 if (priv_euid == root_uid)
69 if (seteuid(priv_euid) != 0)
70 log_write(0, LOG_PANIC_DIE, "seteuid(%d): %s", priv_euid, strerror(errno));
71 if (setegid(priv_egid) != 0)
72 log_write(0, LOG_PANIC_DIE, "setegid(%d): %s", priv_egid, strerror(errno));
73 if (priv_ngroups > 0 && setgroups(priv_ngroups, priv_groups) != 0)
74 log_write(0, LOG_PANIC_DIE, "setgroups: %s", strerror(errno));
76 if (geteuid() != priv_euid)
77 log_write(0, LOG_PANIC_DIE, "getdeuid() != %d", priv_euid);
78 if (getegid() != priv_egid)
79 log_write(0, LOG_PANIC_DIE, "getdegid() != %d", priv_egid);
82 priv_state = PRIV_RESTORED;