-
Notifications
You must be signed in to change notification settings - Fork 0
/
git-auth.c
279 lines (260 loc) · 7.92 KB
/
git-auth.c
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
270
271
272
273
274
275
276
277
278
279
/*
* git-auth - restrict git commands
* Copyright 2012,2021 Thomas de Grivel <thoxdg@gmail.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <assert.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include "rule.h"
#ifndef GIT_AUTH_ID_ENV
#define GIT_AUTH_ID_ENV "GIT_AUTH_ID"
#endif
#ifndef GIT_SHELL
#define GIT_SHELL "git-shell"
#endif
#define CMD_BUFSZ 2048
#define LOG_BUFSZ 2048
static void stracat (char *buf, size_t bufsz, int argc, const char **argv)
{
size_t b = 0;
int a;
assert(buf);
assert(bufsz);
assert(argc);
assert(argv);
for (a = 0; a < argc; a++) {
const char *arg;
if (b >= bufsz - strlen(argv[a]) - 2) {
errno = ENOMEM;
err(1, "stracat");
}
if (a)
buf[b++] = ' ';
arg = argv[a];
while (*arg)
buf[b++] = *(arg++);
}
buf[b] = 0;
}
static void stracat_quoted (char *buf, size_t bufsz, int argc, const char **argv)
{
size_t b = 0;
int a;
assert(buf);
assert(bufsz);
assert(argc);
assert(argv);
for (a = 0; a < argc; a++) {
const char *arg;
if (b >= bufsz - strlen(argv[a]) * 2 - 2) {
errno = ENOMEM;
err(1, "stracat");
}
if (a)
buf[b++] = ' ';
buf[b++] = '"';
arg = argv[a];
while (*arg) {
char c = *(arg++);
if (c == '"')
buf[b++] = '\\';
buf[b++] = c;
}
buf[b++] = '"';
}
buf[b] = 0;
}
static void log_args (const char *op, int argc, const char **argv)
{
char msg[2048];
stracat(msg, sizeof(msg), argc, argv);
syslog(LOG_INFO, "%s %s", op, msg);
}
static void log_rule (const char *op, s_rule *rule)
{
char msg[LOG_BUFSZ];
size_t m = 0;
const char *mode = "?";
m += strlcpy(msg + m, GIT_AUTH_ID_ENV, sizeof(msg) - m);
if (m >= LOG_BUFSZ - 2)
goto overflow;
msg[m++] = '=';
m += strlcpy(msg + m, rule->user, sizeof(msg) - m);
if (m >= LOG_BUFSZ - 2)
goto overflow;
msg[m++] = ' ';
assert(1 <= rule->mode && rule->mode <= 3);
switch (rule->mode) {
case 1: mode = "r"; break;
case 2: mode = "w"; break;
case 3: mode = "rw"; break;
default: fprintf(stderr, "log_rule: invalid mode: %d\n", rule->mode);
}
m += strlcpy(msg + m, mode, sizeof(msg) - m);
if (m >= LOG_BUFSZ - 2)
goto overflow;
msg[m++] = ' ';
m += strlcpy(msg + m, rule->path, sizeof(msg) - m);
syslog(LOG_INFO, "%s %s", op, msg);
return;
overflow:
fprintf(stderr, "git-auth: log_rule: buffer overflow !\n");
}
/*
static void log_rules (s_rule rules[RULES_MAX])
{
int r = 0;
while (rules[r].user) {
char buf[16];
snprintf(buf, 15, "%d", r);
log_rule(buf, &rules[r]);
r++;
}
}
*/
static void log_cmd (const char *op, int argc, const char **argv)
{
char msg[LOG_BUFSZ];
stracat(msg, LOG_BUFSZ, argc, argv);
syslog(LOG_INFO, "%s %s", op, msg);
}
/*
int unquote (char *buf, size_t bufsz, const char *str)
{
size_t len = strlen(str);
assert(len < bufsz);
if (str[0] == '\'' && len > 1 && str[len - 1] == '\'') {
strlcpy(buf, str + 1, bufsz);
buf[len - 2] = 0;
return 1;
}
strlcpy(buf, str, bufsz);
return 0;
}
static int rule_match_path (const char *rule_path, const char *arg_path)
{
char rp[1024];
char ap[1024];
unquote(rp, sizeof(rp), rule_path);
unquote(ap, sizeof(ap), arg_path);
return strcmp(rp, ap) == 0;
}
*/
static int rule_match (s_rule *rule, int argc, const char **argv)
{
assert(rule);
assert(argc);
assert(argv);
if (argc != 3)
return 0;
if (strcmp(rule->user, argv[0]))
return 0;
if (!strcmp(argv[1], "git-upload-pack") && !(rule->mode & 1))
return 0;
else if (!strcmp(argv[1], "git-receive-pack") && !(rule->mode & 2))
return 0;
if (strcmp(rule->path, argv[2]))
return 0;
return 1;
}
static int auth (s_rule rules[RULES_MAX], int argc, const char **argv)
{
int r = 0;
while (rules[r].user) {
/* log_rule("MATCH", &rules[r]); */
if (rule_match(&rules[r], argc, argv)) {
log_rule("ALLOW", &rules[r]);
return 1;
}
/* else
log_rule("DENY", &rules[r]); */
r++;
}
return 0;
}
static void cleanup (void)
{
closelog();
}
static void exec_cmd (int argc, const char **argv)
{
char buf[CMD_BUFSZ];
const char *cmd_argv[4];
assert(argc);
assert(argv);
cmd_argv[0] = GIT_SHELL;
cmd_argv[1] = "-c";
stracat(buf, CMD_BUFSZ, argc - 1, argv + 1);
cmd_argv[2] = buf;
cmd_argv[3] = NULL;
log_cmd("EXEC", 3, cmd_argv);
cleanup();
execvp(cmd_argv[0], (char *const *) cmd_argv);
err(1, "%s", cmd_argv[0]);
}
static void usage (const char *argv0)
{
fprintf(stderr, "Usage: %s=ID %s -c GIT_COMMAND PATH\n",
GIT_AUTH_ID_ENV, argv0);
exit(1);
}
int main (int argc, char **argv)
{
char buf[LOG_BUFSZ];
char *bs;
s_rule rules[RULES_MAX];
const char *git_auth_id;
int auth_ok;
const char *cmd_argv[3];
if (argc != 3) {
char buf[LOG_BUFSZ];
fprintf(stderr, "git-auth: wrong number of arguments: %d.\n", argc);
stracat_quoted(buf, sizeof(buf), argc, (const char **) argv);
fprintf(stderr, "%s\n", buf);
usage(argv[0]);
}
if (strcmp(argv[1], "-c")) {
fprintf(stderr, "expected -c as first argument.\n");
usage(argv[0]);
}
git_auth_id = getenv(GIT_AUTH_ID_ENV);
if (!git_auth_id) {
fprintf(stderr, "missing %s.\n", GIT_AUTH_ID_ENV);
usage(argv[0]);
}
cmd_argv[0] = git_auth_id;
strlcpy(buf, argv[2], LOG_BUFSZ);
cmd_argv[1] = buf;
bs = strchr(buf, ' ');
*bs++ = 0;
cmd_argv[2] = bs;
openlog(argv[0], LOG_PID, LOG_AUTH);
log_args("NEW", argc, (const char **) argv);
read_rules(rules, "/etc/git/auth.conf");
/* log_rules(rules); */
auth_ok = auth(rules, 3, cmd_argv);
log_cmd(auth_ok ? "ALLOW" : "DENY", 3, cmd_argv);
if (auth_ok) {
exec_cmd(3, cmd_argv);
/* never reached */
}
cleanup();
return 1;
}