Missing files during OpenSSH import.
[dragonfly.git] / crypto / openssh-3.8.1p1 / uidswap.c
blob44c4cb626c8a7d10cee86d0da45cb013316f8878
1 /*
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 * Code for uid-swapping.
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".
14 #include "includes.h"
15 RCSID("$OpenBSD: uidswap.c,v 1.24 2003/05/29 16:58:45 deraadt Exp $");
17 #include "log.h"
18 #include "uidswap.h"
19 #include "xmalloc.h"
22 * Note: all these functions must work in all of the following cases:
23 * 1. euid=0, ruid=0
24 * 2. euid=0, ruid!=0
25 * 3. euid!=0, ruid!=0
26 * Additionally, they must work regardless of whether the system has
27 * POSIX saved uids or not.
30 #if defined(_POSIX_SAVED_IDS) && !defined(BROKEN_SAVED_UIDS)
31 /* Lets assume that posix saved ids also work with seteuid, even though that
32 is not part of the posix specification. */
33 #define SAVED_IDS_WORK_WITH_SETEUID
34 /* Saved effective uid. */
35 static uid_t saved_euid = 0;
36 static gid_t saved_egid = 0;
37 #endif
39 /* Saved effective uid. */
40 static int privileged = 0;
41 static int temporarily_use_uid_effective = 0;
42 static gid_t *saved_egroups = NULL, *user_groups = NULL;
43 static int saved_egroupslen = -1, user_groupslen = -1;
46 * Temporarily changes to the given uid. If the effective user
47 * id is not root, this does nothing. This call cannot be nested.
49 void
50 temporarily_use_uid(struct passwd *pw)
52 /* Save the current euid, and egroups. */
53 #ifdef SAVED_IDS_WORK_WITH_SETEUID
54 saved_euid = geteuid();
55 saved_egid = getegid();
56 debug("temporarily_use_uid: %u/%u (e=%u/%u)",
57 (u_int)pw->pw_uid, (u_int)pw->pw_gid,
58 (u_int)saved_euid, (u_int)saved_egid);
59 if (saved_euid != 0) {
60 privileged = 0;
61 return;
63 #else
64 if (geteuid() != 0) {
65 privileged = 0;
66 return;
68 #endif /* SAVED_IDS_WORK_WITH_SETEUID */
70 privileged = 1;
71 temporarily_use_uid_effective = 1;
73 saved_egroupslen = getgroups(0, NULL);
74 if (saved_egroupslen < 0)
75 fatal("getgroups: %.100s", strerror(errno));
76 if (saved_egroupslen > 0) {
77 saved_egroups = xrealloc(saved_egroups,
78 saved_egroupslen * sizeof(gid_t));
79 if (getgroups(saved_egroupslen, saved_egroups) < 0)
80 fatal("getgroups: %.100s", strerror(errno));
81 } else { /* saved_egroupslen == 0 */
82 if (saved_egroups != NULL)
83 xfree(saved_egroups);
86 /* set and save the user's groups */
87 if (user_groupslen == -1) {
88 if (initgroups(pw->pw_name, pw->pw_gid) < 0)
89 fatal("initgroups: %s: %.100s", pw->pw_name,
90 strerror(errno));
92 user_groupslen = getgroups(0, NULL);
93 if (user_groupslen < 0)
94 fatal("getgroups: %.100s", strerror(errno));
95 if (user_groupslen > 0) {
96 user_groups = xrealloc(user_groups,
97 user_groupslen * sizeof(gid_t));
98 if (getgroups(user_groupslen, user_groups) < 0)
99 fatal("getgroups: %.100s", strerror(errno));
100 } else { /* user_groupslen == 0 */
101 if (user_groups)
102 xfree(user_groups);
105 /* Set the effective uid to the given (unprivileged) uid. */
106 if (setgroups(user_groupslen, user_groups) < 0)
107 fatal("setgroups: %.100s", strerror(errno));
108 #ifndef SAVED_IDS_WORK_WITH_SETEUID
109 /* Propagate the privileged gid to all of our gids. */
110 if (setgid(getegid()) < 0)
111 debug("setgid %u: %.100s", (u_int) getegid(), strerror(errno));
112 /* Propagate the privileged uid to all of our uids. */
113 if (setuid(geteuid()) < 0)
114 debug("setuid %u: %.100s", (u_int) geteuid(), strerror(errno));
115 #endif /* SAVED_IDS_WORK_WITH_SETEUID */
116 if (setegid(pw->pw_gid) < 0)
117 fatal("setegid %u: %.100s", (u_int)pw->pw_gid,
118 strerror(errno));
119 if (seteuid(pw->pw_uid) == -1)
120 fatal("seteuid %u: %.100s", (u_int)pw->pw_uid,
121 strerror(errno));
125 * Restores to the original (privileged) uid.
127 void
128 restore_uid(void)
130 /* it's a no-op unless privileged */
131 if (!privileged) {
132 debug("restore_uid: (unprivileged)");
133 return;
135 if (!temporarily_use_uid_effective)
136 fatal("restore_uid: temporarily_use_uid not effective");
138 #ifdef SAVED_IDS_WORK_WITH_SETEUID
139 debug("restore_uid: %u/%u", (u_int)saved_euid, (u_int)saved_egid);
140 /* Set the effective uid back to the saved privileged uid. */
141 if (seteuid(saved_euid) < 0)
142 fatal("seteuid %u: %.100s", (u_int)saved_euid, strerror(errno));
143 if (setegid(saved_egid) < 0)
144 fatal("setegid %u: %.100s", (u_int)saved_egid, strerror(errno));
145 #else /* SAVED_IDS_WORK_WITH_SETEUID */
147 * We are unable to restore the real uid to its unprivileged value.
148 * Propagate the real uid (usually more privileged) to effective uid
149 * as well.
151 setuid(getuid());
152 setgid(getgid());
153 #endif /* SAVED_IDS_WORK_WITH_SETEUID */
155 if (setgroups(saved_egroupslen, saved_egroups) < 0)
156 fatal("setgroups: %.100s", strerror(errno));
157 temporarily_use_uid_effective = 0;
161 * Permanently sets all uids to the given uid. This cannot be
162 * called while temporarily_use_uid is effective.
164 void
165 permanently_set_uid(struct passwd *pw)
167 uid_t old_uid = getuid();
168 gid_t old_gid = getgid();
170 if (temporarily_use_uid_effective)
171 fatal("permanently_set_uid: temporarily_use_uid effective");
172 debug("permanently_set_uid: %u/%u", (u_int)pw->pw_uid,
173 (u_int)pw->pw_gid);
175 #if defined(HAVE_SETRESGID) && !defined(BROKEN_SETRESGID)
176 if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) < 0)
177 fatal("setresgid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
178 #elif defined(HAVE_SETREGID) && !defined(BROKEN_SETREGID)
179 if (setregid(pw->pw_gid, pw->pw_gid) < 0)
180 fatal("setregid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
181 #else
182 if (setegid(pw->pw_gid) < 0)
183 fatal("setegid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
184 if (setgid(pw->pw_gid) < 0)
185 fatal("setgid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
186 #endif
188 #if defined(HAVE_SETRESUID) && !defined(BROKEN_SETRESUID)
189 if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) < 0)
190 fatal("setresuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
191 #elif defined(HAVE_SETREUID) && !defined(BROKEN_SETREUID)
192 if (setreuid(pw->pw_uid, pw->pw_uid) < 0)
193 fatal("setreuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
194 #else
195 # ifndef SETEUID_BREAKS_SETUID
196 if (seteuid(pw->pw_uid) < 0)
197 fatal("seteuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
198 # endif
199 if (setuid(pw->pw_uid) < 0)
200 fatal("setuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
201 #endif
203 /* Try restoration of GID if changed (test clearing of saved gid) */
204 if (old_gid != pw->pw_gid &&
205 (setgid(old_gid) != -1 || setegid(old_gid) != -1))
206 fatal("%s: was able to restore old [e]gid", __func__);
208 /* Verify GID drop was successful */
209 if (getgid() != pw->pw_gid || getegid() != pw->pw_gid) {
210 fatal("%s: egid incorrect gid:%u egid:%u (should be %u)",
211 __func__, (u_int)getgid(), (u_int)getegid(),
212 (u_int)pw->pw_gid);
215 #ifndef HAVE_CYGWIN
216 /* Try restoration of UID if changed (test clearing of saved uid) */
217 if (old_uid != pw->pw_uid &&
218 (setuid(old_uid) != -1 || seteuid(old_uid) != -1))
219 fatal("%s: was able to restore old [e]uid", __func__);
220 #endif
222 /* Verify UID drop was successful */
223 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) {
224 fatal("%s: euid incorrect uid:%u euid:%u (should be %u)",
225 __func__, (u_int)getuid(), (u_int)geteuid(),
226 (u_int)pw->pw_uid);