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
49static bool try_dataset_remove(const char *home);
50extern 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 */
58bool
59rm_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 */
120static bool
121try_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