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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 | |
5260325f | 5 | * Code for uid-swapping. |
bcbf86ec | 6 | * |
7 | * As far as I am concerned, the code I have written for this software | |
8 | * can be used freely for any purpose. Any derived versions of this | |
9 | * software must be clearly marked as such, and if the derived work is | |
10 | * incompatible with the protocol description in the RFC file, it must be | |
11 | * called by a name other than "ssh" or "Secure Shell". | |
5260325f | 12 | */ |
8efc0c15 | 13 | |
14 | #include "includes.h" | |
bcbf86ec | 15 | RCSID("$OpenBSD: uidswap.c,v 1.9 2000/09/07 20:27:55 deraadt Exp $"); |
8efc0c15 | 16 | |
17 | #include "ssh.h" | |
18 | #include "uidswap.h" | |
3206bb3b | 19 | #ifdef WITH_IRIX_AUDIT |
20 | #include <sat.h> | |
21 | #endif /* WITH_IRIX_AUDIT */ | |
8efc0c15 | 22 | |
5260325f | 23 | /* |
24 | * Note: all these functions must work in all of the following cases: | |
25 | * 1. euid=0, ruid=0 | |
26 | * 2. euid=0, ruid!=0 | |
27 | * 3. euid!=0, ruid!=0 | |
28 | * Additionally, they must work regardless of whether the system has | |
29 | * POSIX saved uids or not. | |
30 | */ | |
8efc0c15 | 31 | |
32 | #ifdef _POSIX_SAVED_IDS | |
33 | /* Lets assume that posix saved ids also work with seteuid, even though that | |
34 | is not part of the posix specification. */ | |
35 | #define SAVED_IDS_WORK_WITH_SETEUID | |
8efc0c15 | 36 | |
37 | /* Saved effective uid. */ | |
38 | static uid_t saved_euid = 0; | |
39 | ||
d468fc76 | 40 | #endif /* _POSIX_SAVED_IDS */ |
41 | ||
5260325f | 42 | /* |
43 | * Temporarily changes to the given uid. If the effective user | |
44 | * id is not root, this does nothing. This call cannot be nested. | |
45 | */ | |
6ae2364d | 46 | void |
5260325f | 47 | temporarily_use_uid(uid_t uid) |
8efc0c15 | 48 | { |
49 | #ifdef SAVED_IDS_WORK_WITH_SETEUID | |
5260325f | 50 | /* Save the current euid. */ |
51 | saved_euid = geteuid(); | |
8efc0c15 | 52 | |
5260325f | 53 | /* Set the effective uid to the given (unprivileged) uid. */ |
54 | if (seteuid(uid) == -1) | |
14a9a859 | 55 | debug("seteuid %u: %.100s", (u_int) uid, strerror(errno)); |
8efc0c15 | 56 | #else /* SAVED_IDS_WORK_WITH_SETUID */ |
5260325f | 57 | /* Propagate the privileged uid to all of our uids. */ |
58 | if (setuid(geteuid()) < 0) | |
14a9a859 | 59 | debug("setuid %u: %.100s", (u_int) geteuid(), strerror(errno)); |
8efc0c15 | 60 | |
5260325f | 61 | /* Set the effective uid to the given (unprivileged) uid. */ |
62 | if (seteuid(uid) == -1) | |
14a9a859 | 63 | debug("seteuid %u: %.100s", (u_int) uid, strerror(errno)); |
8efc0c15 | 64 | #endif /* SAVED_IDS_WORK_WITH_SETEUID */ |
8efc0c15 | 65 | } |
66 | ||
5260325f | 67 | /* |
68 | * Restores to the original uid. | |
69 | */ | |
6ae2364d | 70 | void |
5260325f | 71 | restore_uid() |
8efc0c15 | 72 | { |
73 | #ifdef SAVED_IDS_WORK_WITH_SETEUID | |
5260325f | 74 | /* Set the effective uid back to the saved uid. */ |
75 | if (seteuid(saved_euid) < 0) | |
14a9a859 | 76 | debug("seteuid %u: %.100s", (u_int) saved_euid, strerror(errno)); |
8efc0c15 | 77 | #else /* SAVED_IDS_WORK_WITH_SETEUID */ |
aa3378df | 78 | /* |
79 | * We are unable to restore the real uid to its unprivileged value. | |
80 | * Propagate the real uid (usually more privileged) to effective uid | |
81 | * as well. | |
82 | */ | |
5260325f | 83 | setuid(getuid()); |
8efc0c15 | 84 | #endif /* SAVED_IDS_WORK_WITH_SETEUID */ |
85 | } | |
86 | ||
5260325f | 87 | /* |
88 | * Permanently sets all uids to the given uid. This cannot be | |
89 | * called while temporarily_use_uid is effective. | |
90 | */ | |
6ae2364d | 91 | void |
5260325f | 92 | permanently_set_uid(uid_t uid) |
8efc0c15 | 93 | { |
3206bb3b | 94 | #ifdef WITH_IRIX_AUDIT |
95 | if (sysconf(_SC_AUDIT)) { | |
96 | debug("Setting sat id to %d", (int) uid); | |
97 | if (satsetid(uid)) | |
cd352c82 | 98 | debug("error setting satid: %.100s", strerror(errno)); |
3206bb3b | 99 | } |
100 | #endif /* WITH_IRIX_AUDIT */ | |
101 | ||
5260325f | 102 | if (setuid(uid) < 0) |
14a9a859 | 103 | debug("setuid %u: %.100s", (u_int) uid, strerror(errno)); |
8efc0c15 | 104 | } |