1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
|
/*
* Copyright (C) 2017 Firejail Authors
*
* This file is part of firejail project
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "firejail.h"
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#define MAXBUF 4096
static const char * const lib_paths[] = {
"/lib",
"/lib/x86_64-linux-gnu",
"/lib64",
"/usr/lib",
"/usr/lib/x86_64-linux-gnu",
LIBDIR,
"/usr/local/lib",
NULL
}; // Note: this array is duplicated in src/fldd/main.c
static void duplicate(const char *fname, const char *private_run_dir) {
if (arg_debug)
printf("copying %s to private %s\n", fname, private_run_dir);
// copy only root-owned files
struct stat s;
if (stat(fname, &s) == 0 && s.st_uid == 0)
sbox_run(SBOX_ROOT| SBOX_SECCOMP, 4, PATH_FCOPY, "--follow-link", fname, private_run_dir);
}
// requires full path for lib
static void copy_libs(const char *lib, const char *private_run_dir, const char *output_file) {
// if library/executable does not exist or the user does not have read access to it
// print a warning and exit the function.
if (access(lib, R_OK)) {
fwarning("cannot find %s for private-lib, skipping...\n", lib);
return;
}
// create an empty RUN_LIB_FILE and allow the user to write to it
unlink(output_file); // in case is there
create_empty_file_as_root(output_file, 0644);
if (chown(output_file, getuid(), getgid()))
errExit("chown");
// run fldd to extact the list of file
sbox_run(SBOX_USER | SBOX_SECCOMP | SBOX_CAPS_NONE, 3, PATH_FLDD, lib, output_file);
// open the list of libraries and install them on by one
FILE *fp = fopen(output_file, "r");
if (!fp)
errExit("fopen");
char buf[MAXBUF];
while (fgets(buf, MAXBUF, fp)) {
// remove \n
char *ptr = strchr(buf, '\n');
if (ptr)
*ptr = '\0';
duplicate(buf, private_run_dir);
}
fclose(fp);
}
static void copy_directory(const char *full_path, const char *dir_name, const char *private_run_dir) {
char *dest;
if (asprintf(&dest, "%s/%s", private_run_dir, dir_name) == -1)
errExit("asprintf");
// do nothing if the directory is already there
struct stat s;
if (stat(dest, &s) == 0) {
free(dest);
return;
}
// create new directory and mount the original on top of it
mkdir_attr(dest, 0755, 0, 0);
if (mount(full_path, dest, NULL, MS_BIND|MS_REC, NULL) < 0 ||
mount(NULL, dest, NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NODEV|MS_REC, NULL) < 0)
errExit("mount bind");
fs_logger2("clone", full_path);
fs_logger2("mount", full_path);
free(dest);
}
// return 1 if the file is valid
static char *valid_file(const char *lib) {
// filename check
int len = strlen(lib);
if (strcspn(lib, "\\&!?\"'<>%^(){}[];,*") != (size_t)len ||
strstr(lib, "..")) {
fprintf(stderr, "Error: \"%s\" is an invalid library\n", lib);
exit(1);
}
// find the library
int i;
for (i = 0; lib_paths[i]; i++) {
char *fname;
if (asprintf(&fname, "%s/%s", lib_paths[i], lib) == -1)
errExit("asprintf");
// existing file owned by root
struct stat s;
if (stat(fname, &s) == 0 && s.st_uid == 0) {
return fname;
}
free(fname);
}
fwarning("%s library not found, skipping...\n", lib);
return NULL;
}
void fs_private_lib(void) {
#ifndef __x86_64__
fwarning("private-lib feature is currently available only on amd64 platforms\n");
return;
#endif
char *private_list = cfg.lib_private_keep;
if (arg_debug)
printf("Starting private-lib processing: program %s, shell %s\n",
(cfg.original_program_index > 0)? cfg.original_argv[cfg.original_program_index]: "none",
(arg_shell_none)? "none": cfg.shell);
// create /run/firejail/mnt/lib directory
mkdir_attr(RUN_LIB_DIR, 0755, 0, 0);
// fix libselinux linking problem on Debian stretch; the library is
// linked in most basic command utilities (ls, cp, find etc.), and it
// seems to have a path hardlinked under /lib/x86_64-linux-gnu directory.
struct stat s;
if (stat("/lib/x86_64-linux-gnu/libselinux.so.1", &s) == 0) {
mkdir_attr(RUN_LIB_DIR "/x86_64-linux-gnu", 0755, 0, 0);
duplicate("/lib/x86_64-linux-gnu/libselinux.so.1", RUN_LIB_DIR "/x86_64-linux-gnu");
}
// copy the libs in the new lib directory for the main exe
if (cfg.original_program_index > 0)
copy_libs(cfg.original_argv[cfg.original_program_index], RUN_LIB_DIR, RUN_LIB_FILE);
// for the shell
if (!arg_shell_none) {
copy_libs(cfg.shell, RUN_LIB_DIR, RUN_LIB_FILE);
// a shell is useless without ls command
copy_libs("/bin/ls", RUN_LIB_DIR, RUN_LIB_FILE);
}
// for the listed libs
if (private_list && *private_list != '\0') {
if (arg_debug)
printf("Copying extra files (%s) in the new lib directory:\n", private_list);
char *dlist = strdup(private_list);
if (!dlist)
errExit("strdup");
char *ptr = strtok(dlist, ",");
char *lib = valid_file(ptr);
if (lib) {
if (is_dir(lib))
copy_directory(lib, ptr, RUN_LIB_DIR);
else {
duplicate(lib, RUN_LIB_DIR);
copy_libs(lib, RUN_LIB_DIR, RUN_LIB_FILE);
}
free(lib);
}
while ((ptr = strtok(NULL, ",")) != NULL) {
lib = valid_file(ptr);
if (lib) {
if (is_dir(lib))
copy_directory(lib, ptr, RUN_LIB_DIR);
else {
duplicate(lib, RUN_LIB_DIR);
copy_libs(lib, RUN_LIB_DIR, RUN_LIB_FILE);
}
free(lib);
}
}
free(dlist);
fs_logger_print();
}
// for private-bin files
if (arg_private_bin) {
FILE *fp = fopen(RUN_LIB_BIN, "r");
if (fp) {
char buf[MAXBUF];
while (fgets(buf, MAXBUF, fp)) {
// remove \n
char *ptr = strchr(buf, '\n');
if (ptr)
*ptr = '\0';
copy_libs(buf, RUN_LIB_DIR, RUN_LIB_FILE);
}
}
fclose(fp);
}
// for our trace and tracelog libs
if (arg_trace)
duplicate(LIBDIR "/firejail/libtrace.so", RUN_LIB_DIR);
else if (arg_tracelog)
duplicate(LIBDIR "/firejail/libtracelog.so", RUN_LIB_DIR);
if (arg_debug)
printf("Mount-bind %s on top of /lib /lib64 /usr/lib\n", RUN_LIB_DIR);
if (is_dir("/lib")) {
if (mount(RUN_LIB_DIR, "/lib", NULL, MS_BIND|MS_REC, NULL) < 0 ||
mount(NULL, "/lib", NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NODEV|MS_REC, NULL) < 0)
errExit("mount bind");
fs_logger2("tmpfs", "/lib");
fs_logger("mount /lib");
}
if (is_dir("/lib64")) {
if (mount(RUN_LIB_DIR, "/lib64", NULL, MS_BIND|MS_REC, NULL) < 0 ||
mount(NULL, "/lib64", NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NODEV|MS_REC, NULL) < 0)
errExit("mount bind");
fs_logger2("tmpfs", "/lib64");
fs_logger("mount /lib64");
}
if (is_dir("/usr/lib")) {
if (mount(RUN_LIB_DIR, "/usr/lib", NULL, MS_BIND|MS_REC, NULL) < 0 ||
mount(NULL, "/usr/lib", NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NODEV|MS_REC, NULL) < 0)
errExit("mount bind");
fs_logger2("tmpfs", "/usr/lib");
fs_logger("mount /usr/lib");
}
// for amd64 only - we'll deal with i386 later
if (is_dir("/lib32")) {
if (mount(RUN_RO_DIR, "/lib32", "none", MS_BIND, "mode=400,gid=0") < 0)
errExit("disable file");
fs_logger("blacklist-nolog /lib32");
}
if (is_dir("/libx32")) {
if (mount(RUN_RO_DIR, "/libx32", "none", MS_BIND, "mode=400,gid=0") < 0)
errExit("disable file");
fs_logger("blacklist-nolog /libx32");
}
}
|