Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 1 | /* |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| 3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 4 | * All rights reserved |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 5 | * Code for uid-swapping. |
Damien Miller | e4340be | 2000-09-16 13:29:08 +1100 | [diff] [blame] | 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". |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 12 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 13 | |
| 14 | #include "includes.h" |
Damien Miller | e4340be | 2000-09-16 13:29:08 +1100 | [diff] [blame] | 15 | RCSID("$OpenBSD: uidswap.c,v 1.9 2000/09/07 20:27:55 deraadt Exp $"); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 16 | |
| 17 | #include "ssh.h" |
| 18 | #include "uidswap.h" |
| 19 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 20 | /* |
| 21 | * Note: all these functions must work in all of the following cases: |
| 22 | * 1. euid=0, ruid=0 |
| 23 | * 2. euid=0, ruid!=0 |
| 24 | * 3. euid!=0, ruid!=0 |
| 25 | * Additionally, they must work regardless of whether the system has |
| 26 | * POSIX saved uids or not. |
| 27 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 28 | |
| 29 | #ifdef _POSIX_SAVED_IDS |
| 30 | /* Lets assume that posix saved ids also work with seteuid, even though that |
| 31 | is not part of the posix specification. */ |
| 32 | #define SAVED_IDS_WORK_WITH_SETEUID |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 33 | |
| 34 | /* Saved effective uid. */ |
| 35 | static uid_t saved_euid = 0; |
| 36 | |
Damien Miller | ee1c0b3 | 2000-01-21 00:18:15 +1100 | [diff] [blame] | 37 | #endif /* _POSIX_SAVED_IDS */ |
| 38 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 39 | /* |
| 40 | * Temporarily changes to the given uid. If the effective user |
| 41 | * id is not root, this does nothing. This call cannot be nested. |
| 42 | */ |
Damien Miller | 4af5130 | 2000-04-16 11:18:38 +1000 | [diff] [blame] | 43 | void |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 44 | temporarily_use_uid(uid_t uid) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 45 | { |
| 46 | #ifdef SAVED_IDS_WORK_WITH_SETEUID |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 47 | /* Save the current euid. */ |
| 48 | saved_euid = geteuid(); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 49 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 50 | /* Set the effective uid to the given (unprivileged) uid. */ |
| 51 | if (seteuid(uid) == -1) |
Damien Miller | caf6dd6 | 2000-08-29 11:33:50 +1100 | [diff] [blame] | 52 | debug("seteuid %u: %.100s", (u_int) uid, strerror(errno)); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 53 | #else /* SAVED_IDS_WORK_WITH_SETUID */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 54 | /* Propagate the privileged uid to all of our uids. */ |
| 55 | if (setuid(geteuid()) < 0) |
Damien Miller | caf6dd6 | 2000-08-29 11:33:50 +1100 | [diff] [blame] | 56 | debug("setuid %u: %.100s", (u_int) geteuid(), strerror(errno)); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 57 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 58 | /* Set the effective uid to the given (unprivileged) uid. */ |
| 59 | if (seteuid(uid) == -1) |
Damien Miller | caf6dd6 | 2000-08-29 11:33:50 +1100 | [diff] [blame] | 60 | debug("seteuid %u: %.100s", (u_int) uid, strerror(errno)); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 61 | #endif /* SAVED_IDS_WORK_WITH_SETEUID */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 62 | } |
| 63 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 64 | /* |
| 65 | * Restores to the original uid. |
| 66 | */ |
Damien Miller | 4af5130 | 2000-04-16 11:18:38 +1000 | [diff] [blame] | 67 | void |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 68 | restore_uid() |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 69 | { |
| 70 | #ifdef SAVED_IDS_WORK_WITH_SETEUID |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 71 | /* Set the effective uid back to the saved uid. */ |
| 72 | if (seteuid(saved_euid) < 0) |
Damien Miller | caf6dd6 | 2000-08-29 11:33:50 +1100 | [diff] [blame] | 73 | debug("seteuid %u: %.100s", (u_int) saved_euid, strerror(errno)); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 74 | #else /* SAVED_IDS_WORK_WITH_SETEUID */ |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 75 | /* |
| 76 | * We are unable to restore the real uid to its unprivileged value. |
| 77 | * Propagate the real uid (usually more privileged) to effective uid |
| 78 | * as well. |
| 79 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 80 | setuid(getuid()); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 81 | #endif /* SAVED_IDS_WORK_WITH_SETEUID */ |
| 82 | } |
| 83 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 84 | /* |
| 85 | * Permanently sets all uids to the given uid. This cannot be |
| 86 | * called while temporarily_use_uid is effective. |
| 87 | */ |
Damien Miller | 4af5130 | 2000-04-16 11:18:38 +1000 | [diff] [blame] | 88 | void |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 89 | permanently_set_uid(uid_t uid) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 90 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 91 | if (setuid(uid) < 0) |
Damien Miller | caf6dd6 | 2000-08-29 11:33:50 +1100 | [diff] [blame] | 92 | debug("setuid %u: %.100s", (u_int) uid, strerror(errno)); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 93 | } |