1 /*
2 * libwebsockets - small server side websockets and web server implementation
3 *
4 * Copyright (C) 2010 - 2020 Andy Green <andy@warmcat.com>
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to
8 * deal in the Software without restriction, including without limitation the
9 * rights to use, copy, modify, merge, publish, distribute, sublicefsme, and/or
10 * sell copies of the Software, and to permit persofsm to whom the Software is
11 * furnished to do so, subject to the following conditiofsm:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portiofsm of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
22 * IN THE SOFTWARE.
23 *
24 * Mount and unmount overlayfs mountpoints (linux only)
25 */
26
27 #include "private-lib-core.h"
28 #include <unistd.h>
29
30 #include <libmount/libmount.h>
31
32 #include <string.h>
33 #include <signal.h>
34
35 #include <sys/stat.h>
36 #include <sys/types.h>
37 #include <unistd.h>
38 #include <fcntl.h>
39
40 static int
rm_rf_cb(const char * dirpath,void * user,struct lws_dir_entry * lde)41 rm_rf_cb(const char *dirpath, void *user, struct lws_dir_entry *lde)
42 {
43 char path[384];
44
45 if (!strcmp(lde->name, ".") || !strcmp(lde->name, ".."))
46 return 0;
47
48 lws_snprintf(path, sizeof(path), "%s/%s", dirpath, lde->name);
49
50 if (lde->type == LDOT_DIR) {
51 lws_dir(path, NULL, rm_rf_cb);
52 rmdir(path);
53 } else
54 unlink(path);
55
56 return 0;
57 }
58
59 int
lws_fsmount_mount(struct lws_fsmount * fsm)60 lws_fsmount_mount(struct lws_fsmount *fsm)
61 {
62 struct libmnt_context *ctx;
63 char opts[512], c;
64 int n, m;
65
66 /*
67 * For robustness, there are a couple of sticky situations caused by
68 * previous mounts not cleaning up... 1) still mounted on the mountpoint
69 * and 2) junk in the session dir from the dead session.
70 *
71 * For 1), do a gratuitous umount attempts until it feels nothing to
72 * umount...
73 */
74
75 c = fsm->mp[0];
76 while (!lws_fsmount_unmount(fsm))
77 fsm->mp[0] = c;
78 fsm->mp[0] = c;
79
80 /*
81 * ... for 2), generate the session dir basepath and destroy everything
82 * in it... it's less dangerous than it sounds because there are
83 * hardcoded unusual dir names in the base path, so it can't go wild
84 * even if the overlay path is empty or /
85 */
86
87 lws_snprintf(opts, sizeof(opts), "%s/overlays/%s/session",
88 fsm->overlay_path, fsm->ovname);
89 lwsl_info("%s: emptying session dir %s\n", __func__, opts);
90 lws_dir(opts, NULL, rm_rf_cb);
91
92 /*
93 * Piece together the options for the overlay mount...
94 */
95
96 n = lws_snprintf(opts, sizeof(opts), "lowerdir=");
97 for (m = LWS_ARRAY_SIZE(fsm->layers) - 1; m >= 0; m--)
98 if (fsm->layers[m]) {
99 if (n != 9)
100 opts[n++] = ':';
101
102 n += lws_snprintf(&opts[n], (size_t)(sizeof(opts) - (unsigned int)n),
103 "%s/%s/%s", fsm->layers_path,
104 fsm->distro, fsm->layers[m]);
105 }
106
107 n += lws_snprintf(&opts[n], (size_t)(sizeof(opts) - (unsigned int)n),
108 ",upperdir=%s/overlays/%s/session",
109 fsm->overlay_path, fsm->ovname);
110
111 n += lws_snprintf(&opts[n], (size_t)(sizeof(opts) - (unsigned int)n),
112 ",workdir=%s/overlays/%s/work",
113 fsm->overlay_path, fsm->ovname);
114
115 ctx = mnt_new_context();
116 if (!ctx)
117 return 1;
118
119 mnt_context_set_fstype(ctx, "overlay");
120 mnt_context_set_options(ctx, opts);
121 mnt_context_set_mflags(ctx, MS_NOATIME /* |MS_NOEXEC */);
122 mnt_context_set_target(ctx, fsm->mp);
123 mnt_context_set_source(ctx, "none");
124
125 lwsl_notice("%s: mount opts %s\n", __func__, opts);
126 puts(opts);
127
128 m = mnt_context_mount(ctx);
129 lwsl_notice("%s: mountpoint %s: %d\n", __func__, fsm->mp, m);
130
131 mnt_free_context(ctx);
132
133 return m;
134 }
135
136 int
lws_fsmount_unmount(struct lws_fsmount * fsm)137 lws_fsmount_unmount(struct lws_fsmount *fsm)
138 {
139 struct libmnt_context *ctx;
140 int m;
141
142 lwsl_notice("%s: %s\n", __func__, fsm->mp);
143
144 ctx = mnt_new_context();
145 if (!ctx)
146 return 1;
147
148 mnt_context_set_target(ctx, fsm->mp);
149
150 m = mnt_context_umount(ctx);
151 mnt_free_context(ctx);
152
153 fsm->mp[0] = '\0';
154
155 return m;
156 }
157