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8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Created: Sat Sep 9 01:56:14 1995 ylo | |
6 | * Code for uid-swapping. | |
7 | */ | |
8efc0c15 | 8 | |
9 | #include "includes.h" | |
10 | RCSID("$Id$"); | |
11 | ||
12 | #include "ssh.h" | |
13 | #include "uidswap.h" | |
14 | ||
5260325f | 15 | /* |
16 | * Note: all these functions must work in all of the following cases: | |
17 | * 1. euid=0, ruid=0 | |
18 | * 2. euid=0, ruid!=0 | |
19 | * 3. euid!=0, ruid!=0 | |
20 | * Additionally, they must work regardless of whether the system has | |
21 | * POSIX saved uids or not. | |
22 | */ | |
8efc0c15 | 23 | |
24 | #ifdef _POSIX_SAVED_IDS | |
25 | /* Lets assume that posix saved ids also work with seteuid, even though that | |
26 | is not part of the posix specification. */ | |
27 | #define SAVED_IDS_WORK_WITH_SETEUID | |
8efc0c15 | 28 | |
29 | /* Saved effective uid. */ | |
30 | static uid_t saved_euid = 0; | |
31 | ||
d468fc76 | 32 | #endif /* _POSIX_SAVED_IDS */ |
33 | ||
5260325f | 34 | /* |
35 | * Temporarily changes to the given uid. If the effective user | |
36 | * id is not root, this does nothing. This call cannot be nested. | |
37 | */ | |
6ae2364d | 38 | void |
5260325f | 39 | temporarily_use_uid(uid_t uid) |
8efc0c15 | 40 | { |
41 | #ifdef SAVED_IDS_WORK_WITH_SETEUID | |
5260325f | 42 | /* Save the current euid. */ |
43 | saved_euid = geteuid(); | |
8efc0c15 | 44 | |
5260325f | 45 | /* Set the effective uid to the given (unprivileged) uid. */ |
46 | if (seteuid(uid) == -1) | |
47 | debug("seteuid %d: %.100s", (int) uid, strerror(errno)); | |
8efc0c15 | 48 | #else /* SAVED_IDS_WORK_WITH_SETUID */ |
5260325f | 49 | /* Propagate the privileged uid to all of our uids. */ |
50 | if (setuid(geteuid()) < 0) | |
51 | debug("setuid %d: %.100s", (int) geteuid(), strerror(errno)); | |
8efc0c15 | 52 | |
5260325f | 53 | /* Set the effective uid to the given (unprivileged) uid. */ |
54 | if (seteuid(uid) == -1) | |
55 | debug("seteuid %d: %.100s", (int) uid, strerror(errno)); | |
8efc0c15 | 56 | #endif /* SAVED_IDS_WORK_WITH_SETEUID */ |
8efc0c15 | 57 | } |
58 | ||
5260325f | 59 | /* |
60 | * Restores to the original uid. | |
61 | */ | |
6ae2364d | 62 | void |
5260325f | 63 | restore_uid() |
8efc0c15 | 64 | { |
65 | #ifdef SAVED_IDS_WORK_WITH_SETEUID | |
5260325f | 66 | /* Set the effective uid back to the saved uid. */ |
67 | if (seteuid(saved_euid) < 0) | |
68 | debug("seteuid %d: %.100s", (int) saved_euid, strerror(errno)); | |
8efc0c15 | 69 | #else /* SAVED_IDS_WORK_WITH_SETEUID */ |
aa3378df | 70 | /* |
71 | * We are unable to restore the real uid to its unprivileged value. | |
72 | * Propagate the real uid (usually more privileged) to effective uid | |
73 | * as well. | |
74 | */ | |
5260325f | 75 | setuid(getuid()); |
8efc0c15 | 76 | #endif /* SAVED_IDS_WORK_WITH_SETEUID */ |
77 | } | |
78 | ||
5260325f | 79 | /* |
80 | * Permanently sets all uids to the given uid. This cannot be | |
81 | * called while temporarily_use_uid is effective. | |
82 | */ | |
6ae2364d | 83 | void |
5260325f | 84 | permanently_set_uid(uid_t uid) |
8efc0c15 | 85 | { |
5260325f | 86 | if (setuid(uid) < 0) |
87 | debug("setuid %d: %.100s", (int) uid, strerror(errno)); | |
8efc0c15 | 88 | } |