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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
ee645080 LP |
2 | /*** |
3 | This file is part of systemd. | |
4 | ||
5 | Copyright 2015 Lennart Poettering | |
6 | ||
7 | systemd is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU Lesser General Public License as published by | |
9 | the Free Software Foundation; either version 2.1 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | systemd is distributed in the hope that it will be useful, but | |
13 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | Lesser General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU Lesser General Public License | |
18 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
19 | ***/ | |
20 | ||
07630cea | 21 | #include <grp.h> |
ee645080 LP |
22 | #include <sys/types.h> |
23 | #include <unistd.h> | |
ee645080 | 24 | |
b5efdb8a | 25 | #include "alloc-util.h" |
c5b82d86 | 26 | #include "def.h" |
dccca82b | 27 | #include "errno.h" |
3ffd4af2 | 28 | #include "fd-util.h" |
c5b82d86 | 29 | #include "fileio.h" |
ee645080 | 30 | #include "mkdir.h" |
3ffd4af2 | 31 | #include "nspawn-setuid.h" |
ee645080 | 32 | #include "process-util.h" |
07630cea LP |
33 | #include "signal-util.h" |
34 | #include "string-util.h" | |
5018c0c9 | 35 | #include "strv.h" |
b1d4f8e1 | 36 | #include "user-util.h" |
07630cea | 37 | #include "util.h" |
ee645080 LP |
38 | |
39 | static int spawn_getent(const char *database, const char *key, pid_t *rpid) { | |
4c253ed1 | 40 | int pipe_fds[2], r; |
ee645080 LP |
41 | pid_t pid; |
42 | ||
43 | assert(database); | |
44 | assert(key); | |
45 | assert(rpid); | |
46 | ||
47 | if (pipe2(pipe_fds, O_CLOEXEC) < 0) | |
48 | return log_error_errno(errno, "Failed to allocate pipe: %m"); | |
49 | ||
b6e1fff1 | 50 | r = safe_fork("(getent)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_LOG, &pid); |
05a8b330 LP |
51 | if (r < 0) { |
52 | safe_close_pair(pipe_fds); | |
b6e1fff1 | 53 | return r; |
05a8b330 | 54 | } |
4c253ed1 | 55 | if (r == 0) { |
ee645080 LP |
56 | char *empty_env = NULL; |
57 | ||
2b33ab09 | 58 | safe_close(pipe_fds[0]); |
ee645080 | 59 | |
2b33ab09 | 60 | if (rearrange_stdio(-1, pipe_fds[1], -1) < 0) |
ee645080 LP |
61 | _exit(EXIT_FAILURE); |
62 | ||
ee645080 LP |
63 | close_all_fds(NULL, 0); |
64 | ||
65 | execle("/usr/bin/getent", "getent", database, key, NULL, &empty_env); | |
66 | execle("/bin/getent", "getent", database, key, NULL, &empty_env); | |
67 | _exit(EXIT_FAILURE); | |
68 | } | |
69 | ||
70 | pipe_fds[1] = safe_close(pipe_fds[1]); | |
71 | ||
72 | *rpid = pid; | |
73 | ||
74 | return pipe_fds[0]; | |
75 | } | |
76 | ||
77 | int change_uid_gid(const char *user, char **_home) { | |
c5b82d86 | 78 | char *x, *u, *g, *h; |
ee645080 LP |
79 | const char *word, *state; |
80 | _cleanup_free_ uid_t *uids = NULL; | |
c5b82d86 | 81 | _cleanup_free_ char *home = NULL, *line = NULL; |
ee645080 LP |
82 | _cleanup_fclose_ FILE *f = NULL; |
83 | _cleanup_close_ int fd = -1; | |
84 | unsigned n_uids = 0; | |
85 | size_t sz = 0, l; | |
86 | uid_t uid; | |
87 | gid_t gid; | |
88 | pid_t pid; | |
89 | int r; | |
90 | ||
91 | assert(_home); | |
92 | ||
5018c0c9 | 93 | if (!user || STR_IN_SET(user, "root", "0")) { |
ee645080 LP |
94 | /* Reset everything fully to 0, just in case */ |
95 | ||
96 | r = reset_uid_gid(); | |
97 | if (r < 0) | |
98 | return log_error_errno(r, "Failed to become root: %m"); | |
99 | ||
100 | *_home = NULL; | |
101 | return 0; | |
102 | } | |
103 | ||
104 | /* First, get user credentials */ | |
105 | fd = spawn_getent("passwd", user, &pid); | |
106 | if (fd < 0) | |
107 | return fd; | |
108 | ||
c5b82d86 | 109 | f = fdopen(fd, "re"); |
ee645080 LP |
110 | if (!f) |
111 | return log_oom(); | |
112 | fd = -1; | |
113 | ||
c5b82d86 LP |
114 | r = read_line(f, LONG_LINE_MAX, &line); |
115 | if (r == 0) { | |
116 | log_error("Failed to resolve user %s.", user); | |
117 | return -ESRCH; | |
ee645080 | 118 | } |
c5b82d86 LP |
119 | if (r < 0) |
120 | return log_error_errno(r, "Failed to read from getent: %m"); | |
ee645080 | 121 | |
7d4904fe | 122 | (void) wait_for_terminate_and_check("getent passwd", pid, WAIT_LOG); |
ee645080 LP |
123 | |
124 | x = strchr(line, ':'); | |
125 | if (!x) { | |
126 | log_error("/etc/passwd entry has invalid user field."); | |
127 | return -EIO; | |
128 | } | |
129 | ||
130 | u = strchr(x+1, ':'); | |
131 | if (!u) { | |
132 | log_error("/etc/passwd entry has invalid password field."); | |
133 | return -EIO; | |
134 | } | |
135 | ||
136 | u++; | |
137 | g = strchr(u, ':'); | |
138 | if (!g) { | |
139 | log_error("/etc/passwd entry has invalid UID field."); | |
140 | return -EIO; | |
141 | } | |
142 | ||
143 | *g = 0; | |
144 | g++; | |
145 | x = strchr(g, ':'); | |
146 | if (!x) { | |
147 | log_error("/etc/passwd entry has invalid GID field."); | |
148 | return -EIO; | |
149 | } | |
150 | ||
151 | *x = 0; | |
152 | h = strchr(x+1, ':'); | |
153 | if (!h) { | |
154 | log_error("/etc/passwd entry has invalid GECOS field."); | |
155 | return -EIO; | |
156 | } | |
157 | ||
158 | h++; | |
159 | x = strchr(h, ':'); | |
160 | if (!x) { | |
161 | log_error("/etc/passwd entry has invalid home directory field."); | |
162 | return -EIO; | |
163 | } | |
164 | ||
165 | *x = 0; | |
166 | ||
167 | r = parse_uid(u, &uid); | |
168 | if (r < 0) { | |
169 | log_error("Failed to parse UID of user."); | |
170 | return -EIO; | |
171 | } | |
172 | ||
173 | r = parse_gid(g, &gid); | |
174 | if (r < 0) { | |
175 | log_error("Failed to parse GID of user."); | |
176 | return -EIO; | |
177 | } | |
178 | ||
179 | home = strdup(h); | |
180 | if (!home) | |
181 | return log_oom(); | |
182 | ||
c5b82d86 LP |
183 | f = safe_fclose(f); |
184 | line = mfree(line); | |
185 | ||
ee645080 LP |
186 | /* Second, get group memberships */ |
187 | fd = spawn_getent("initgroups", user, &pid); | |
188 | if (fd < 0) | |
189 | return fd; | |
190 | ||
c5b82d86 | 191 | f = fdopen(fd, "re"); |
ee645080 LP |
192 | if (!f) |
193 | return log_oom(); | |
194 | fd = -1; | |
195 | ||
c5b82d86 LP |
196 | r = read_line(f, LONG_LINE_MAX, &line); |
197 | if (r == 0) { | |
198 | log_error("Failed to resolve user %s.", user); | |
199 | return -ESRCH; | |
ee645080 | 200 | } |
c5b82d86 LP |
201 | if (r < 0) |
202 | return log_error_errno(r, "Failed to read from getent: %m"); | |
ee645080 | 203 | |
7d4904fe | 204 | (void) wait_for_terminate_and_check("getent initgroups", pid, WAIT_LOG); |
ee645080 LP |
205 | |
206 | /* Skip over the username and subsequent separator whitespace */ | |
207 | x = line; | |
208 | x += strcspn(x, WHITESPACE); | |
209 | x += strspn(x, WHITESPACE); | |
210 | ||
211 | FOREACH_WORD(word, l, x, state) { | |
212 | char c[l+1]; | |
213 | ||
214 | memcpy(c, word, l); | |
215 | c[l] = 0; | |
216 | ||
217 | if (!GREEDY_REALLOC(uids, sz, n_uids+1)) | |
218 | return log_oom(); | |
219 | ||
220 | r = parse_uid(c, &uids[n_uids++]); | |
c7f9a8d2 LP |
221 | if (r < 0) |
222 | return log_error_errno(r, "Failed to parse group data from getent: %m"); | |
ee645080 LP |
223 | } |
224 | ||
225 | r = mkdir_parents(home, 0775); | |
226 | if (r < 0) | |
227 | return log_error_errno(r, "Failed to make home root directory: %m"); | |
228 | ||
d50b5839 | 229 | r = mkdir_safe(home, 0755, uid, gid, 0); |
37c1d5e9 | 230 | if (r < 0 && !IN_SET(r, -EEXIST, -ENOTDIR)) |
ee645080 LP |
231 | return log_error_errno(r, "Failed to make home directory: %m"); |
232 | ||
233 | (void) fchown(STDIN_FILENO, uid, gid); | |
234 | (void) fchown(STDOUT_FILENO, uid, gid); | |
235 | (void) fchown(STDERR_FILENO, uid, gid); | |
236 | ||
237 | if (setgroups(n_uids, uids) < 0) | |
238 | return log_error_errno(errno, "Failed to set auxiliary groups: %m"); | |
239 | ||
240 | if (setresgid(gid, gid, gid) < 0) | |
d2b8497d | 241 | return log_error_errno(errno, "setresgid() failed: %m"); |
ee645080 LP |
242 | |
243 | if (setresuid(uid, uid, uid) < 0) | |
d2b8497d | 244 | return log_error_errno(errno, "setresuid() failed: %m"); |
ee645080 | 245 | |
1cc6c93a YW |
246 | if (_home) |
247 | *_home = TAKE_PTR(home); | |
ee645080 LP |
248 | |
249 | return 0; | |
250 | } |