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
|
/*
* Copyright (C) 2014-2023 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 "../include/common.h"
#define MAXBUF 4098
#define MAXARGS 16
static char *args[MAXARGS] = {0};
static int argcnt = 0;
int arg_quiet = 0;
static char *default_filter =
"*filter\n"
":INPUT DROP [0:0]\n"
":FORWARD DROP [0:0]\n"
":OUTPUT ACCEPT [0:0]\n"
"-A INPUT -i lo -j ACCEPT\n"
"-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT\n"
"# echo replay is handled by -m state RELATED/ESTABLISHED above\n"
"#-A INPUT -p icmp --icmp-type echo-reply -j ACCEPT\n"
"-A INPUT -p icmp --icmp-type destination-unreachable -j ACCEPT\n"
"-A INPUT -p icmp --icmp-type time-exceeded -j ACCEPT\n"
"-A INPUT -p icmp --icmp-type echo-request -j ACCEPT \n"
"# disable STUN\n"
"-A OUTPUT -p udp --dport 3478 -j DROP\n"
"-A OUTPUT -p udp --dport 3479 -j DROP\n"
"-A OUTPUT -p tcp --dport 3478 -j DROP\n"
"-A OUTPUT -p tcp --dport 3479 -j DROP\n"
"COMMIT\n";
static void usage(void) {
printf("Usage:\n");
printf("\tfnetfilter netfilter-command destination-file\n");
}
static void err_exit_cannot_open_file(const char *fname) {
fprintf(stderr, "Error fnetfilter: cannot open %s\n", fname);
exit(1);
}
static void copy(const char *src, const char *dest) {
FILE *fp1 = fopen(src, "r");
if (!fp1)
err_exit_cannot_open_file(src);
FILE *fp2 = fopen(dest, "w");
if (!fp2)
err_exit_cannot_open_file(dest);
char buf[MAXBUF];
while (fgets(buf, MAXBUF, fp1))
fprintf(fp2, "%s", buf);
fclose(fp1);
fclose(fp2);
}
static void process_template(char *src, const char *dest) {
char *arg_start = strchr(src, ',');
assert(arg_start);
*arg_start = '\0';
arg_start++;
if (*arg_start == '\0') {
fprintf(stderr, "Error fnetfilter: you need to provide at least one argument\n");
exit(1);
}
// extract the arguments from command line
char *token = strtok(arg_start, ",");
while (token) {
if (argcnt == MAXARGS) {
fprintf(stderr, "Error fnetfilter: only up to %u arguments are supported\n", (unsigned) MAXARGS);
exit(1);
}
// look for abnormal things
int len = strlen(token);
if (strcspn(token, "\\&!?\"'<>%^(){};,*[]") != (size_t)len) {
fprintf(stderr, "Error fnetfilter: invalid argument in netfilter command\n");
exit(1);
}
args[argcnt] = token;
argcnt++;
token = strtok(NULL, ",");
}
#if 0
{
printf("argcnt %d\n", argcnt);
int i;
for (i = 0; i < argcnt; i++)
printf("%s\n", args[i]);
}
#endif
// open the files
FILE *fp1 = fopen(src, "r");
if (!fp1)
err_exit_cannot_open_file(src);
FILE *fp2 = fopen(dest, "w");
if (!fp2)
err_exit_cannot_open_file(dest);
int line = 0;
char buf[MAXBUF];
while (fgets(buf, MAXBUF, fp1)) {
line++;
char *ptr = buf;
while (*ptr != '\0') {
if (*ptr != '$')
fputc(*ptr, fp2);
else {
// parsing
int index = 0;
int rv = sscanf(ptr, "$ARG%d", &index) ;
if (rv != 1) {
fprintf(stderr, "Error fnetfilter: invalid template argument on line %d\n", line);
exit(1);
}
// print argument
if (index < 1 || index > argcnt) {
fprintf(stderr, "Error fnetfilter: $ARG%d on line %d was not defined\n", index, line);
exit(1);
}
fprintf(fp2, "%s", args[index - 1]);
// march to the end of argument
ptr += 4;
while (isdigit(*ptr))
ptr++;
ptr--;
}
ptr++;
}
}
fclose(fp1);
fclose(fp2);
}
int main(int argc, char **argv) {
#if 0
{
system("cat /proc/self/status");
int i;
for (i = 0; i < argc; i++)
printf("*%s* ", argv[i]);
printf("\n");
}
#endif
char *quiet = getenv("FIREJAIL_QUIET");
if (quiet && strcmp(quiet, "yes") == 0)
arg_quiet = 1;
if (argc > 1 && (strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") ==0)) {
usage();
return 0;
}
if (argc != 2 && argc != 3) {
usage();
return 1;
}
warn_dumpable();
char *destfile = (argc == 3)? argv[2]: argv[1];
char *command = (argc == 3)? argv[1]: NULL;
//printf("command %s\n", command);
//printf("destfile %s\n", destfile);
// destfile is a real filename
reject_meta_chars(destfile, 0);
// handle default config (command = NULL, destfile)
if (command == NULL) {
// create a default filter file
FILE *fp = fopen(destfile, "w");
if (!fp)
err_exit_cannot_open_file(destfile);
fprintf(fp, "%s\n", default_filter);
fclose(fp);
}
else {
if (strrchr(command, ','))
process_template(command, destfile);
else
copy(command, destfile);
}
return 0;
}
|
