1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (C) 1996
5 * David L. Nugent. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY DAVID L. NUGENT AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL DAVID L. NUGENT OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/param.h>
30 #include <sys/mount.h>
31 #include <sys/stat.h>
32 #include <sys/wait.h>
33
34 #include <dirent.h>
35 #include <err.h>
36 #include <errno.h>
37 #include <fcntl.h>
38 #include <libgen.h>
39 #include <libutil.h>
40 #include <spawn.h>
41 #include <stdbool.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <unistd.h>
46
47 #include "pwupd.h"
48
49 static bool try_dataset_remove(const char *home);
50 extern char **environ;
51
52 /*
53 * "rm -r" a directory tree. If the top-level directory cannot be removed
54 * due to EBUSY, indicating that it is a ZFS dataset, and we have emptied
55 * it, destroy the dataset. Return true if any files or directories
56 * remain.
57 */
58 bool
rm_r(int rootfd,const char * path,uid_t uid)59 rm_r(int rootfd, const char *path, uid_t uid)
60 {
61 int dirfd;
62 DIR *d;
63 struct dirent *e;
64 struct stat st;
65 const char *fullpath;
66 bool skipped = false;
67
68 fullpath = path;
69 if (*path == '/')
70 path++;
71
72 dirfd = openat(rootfd, path, O_DIRECTORY);
73 if (dirfd == -1) {
74 return (true);
75 }
76
77 d = fdopendir(dirfd);
78 if (d == NULL) {
79 (void)close(dirfd);
80 return (true);
81 }
82 while ((e = readdir(d)) != NULL) {
83 if (strcmp(e->d_name, ".") == 0 || strcmp(e->d_name, "..") == 0)
84 continue;
85
86 if (fstatat(dirfd, e->d_name, &st, AT_SYMLINK_NOFOLLOW) != 0)
87 continue;
88 if (S_ISDIR(st.st_mode)) {
89 if (rm_r(dirfd, e->d_name, uid) == true)
90 skipped = true;
91 } else if (S_ISLNK(st.st_mode) || st.st_uid == uid)
92 unlinkat(dirfd, e->d_name, 0);
93 else
94 skipped = true;
95 }
96 closedir(d);
97 if (fstatat(rootfd, path, &st, AT_SYMLINK_NOFOLLOW) != 0)
98 return (skipped);
99 if (S_ISLNK(st.st_mode)) {
100 if (unlinkat(rootfd, path, 0) == -1)
101 skipped = true;
102 } else if (st.st_uid == uid) {
103 if (unlinkat(rootfd, path, AT_REMOVEDIR) == -1) {
104 if (errno == EBUSY && skipped == false)
105 skipped = try_dataset_remove(fullpath);
106 else
107 skipped = true;
108 }
109 } else
110 skipped = true;
111
112 return (skipped);
113 }
114
115 /*
116 * If the home directory is a ZFS dataset, attempt to destroy it.
117 * Return true if the dataset is not destroyed.
118 * This would be more straightforward as a shell script.
119 */
120 static bool
try_dataset_remove(const char * path)121 try_dataset_remove(const char *path)
122 {
123 bool skipped = true;
124 struct statfs stat;
125 const char *argv[] = {
126 "/sbin/zfs",
127 "destroy",
128 NULL,
129 NULL
130 };
131 int status;
132 pid_t pid;
133
134 /* see if this is an absolute path (top-level directory) */
135 if (*path != '/')
136 return (skipped);
137 /* see if ZFS is loaded */
138 if (kld_isloaded("zfs") == 0)
139 return (skipped);
140 /* This won't work if root dir is not / (-R option) */
141 if (strcmp(conf.rootdir, "/") != 0) {
142 warnx("cannot destroy home dataset when -R was used");
143 return (skipped);
144 }
145 /* if so, find dataset name */
146 if (statfs(path, &stat) != 0) {
147 warn("statfs %s", path);
148 return (skipped);
149 }
150 /*
151 * Check that the path refers to the dataset itself,
152 * not a subdirectory.
153 */
154 if (strcmp(stat.f_mntonname, path) != 0)
155 return (skipped);
156 argv[2] = stat.f_mntfromname;
157 if ((skipped = posix_spawn(&pid, argv[0], NULL, NULL,
158 (char *const *) argv, environ)) != 0) {
159 warn("Failed to execute '%s %s %s'",
160 argv[0], argv[1], argv[2]);
161 } else {
162 if (waitpid(pid, &status, 0) != -1 && status != 0) {
163 warnx("'%s %s %s' exit status %d\n",
164 argv[0], argv[1], argv[2], status);
165 }
166 }
167 return (skipped);
168 }
169