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
|
#include <alloca.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
/* This will be running setuid root, so be careful! */
static char * safeEnviron[] = {
"PATH=/bin:/sbin:/usr/bin:/usr/sbin",
"HOME=/root",
NULL
};
#define FOUND_FALSE -1
#define NOT_FOUND 0
#define FOUND_TRUE 1
static void
usage(void) {
fprintf(stderr, "usage: usernetctl <interface-config> <up|down|report>\n");
exit(1);
}
static size_t
testSafe(char *ifaceConfig) {
struct stat sb;
/* These shouldn't be symbolic links -- anal, but that's fine w/ mkj. */
if (lstat(ifaceConfig, &sb)) {
fprintf(stderr, "failed to stat %s: %s\n", ifaceConfig,
strerror(errno));
exit(1);
}
/* Safety/sanity checks. */
if (!S_ISREG(sb.st_mode)) {
fprintf(stderr, "%s is not a normal file\n", ifaceConfig);
exit(1);
}
if (sb.st_uid) {
fprintf(stderr, "%s should be owned by root\n", ifaceConfig);
exit(1);
}
if (sb.st_mode & S_IWOTH) {
fprintf(stderr, "%s should not be world writeable\n", ifaceConfig);
exit(1);
}
return sb.st_size;
}
static int
userCtl(char *file) {
char *buf;
char *contents = NULL;
char *chptr = NULL;
char *next = NULL;
int fd = -1, retval = NOT_FOUND;
size_t size = 0;
size = testSafe(file);
buf = contents = malloc(size + 2);
if ((fd = open(file, O_RDONLY)) == -1) {
fprintf(stderr, "failed to open %s: %s\n", file, strerror(errno));
exit(1);
}
if (read(fd, contents, size) != size) {
perror("error reading device configuration");
exit(1);
}
close(fd);
contents[size] = '\n';
contents[size + 1] = '\0';
/* Each pass parses a single line (until an answer is found), The contents
pointer itself points to the beginning of the current line. */
while (*contents) {
chptr = contents;
while (*chptr != '\n') chptr++;
next = chptr + 1;
while (chptr >= contents && isspace(*chptr)) chptr--;
*(++chptr) = '\0';
if (!strncmp(contents, "USERCTL=", 8)) {
contents += 8;
if ((contents[0] == '"' &&
contents[strlen(contents) - 1] == '"') ||
(contents[0] == '\'' &&
contents[strlen(contents) - 1] == '\''))
{
contents++;
contents[strlen(contents) - 1] = '\0';
}
if (!strcmp(contents, "yes") || !strcmp(contents, "true"))
retval = FOUND_TRUE;
else
retval = FOUND_FALSE;
break;
}
contents = next;
}
free(buf);
return retval;
}
int
main(int argc, char ** argv) {
char * ifaceConfig;
char * chptr;
char * cmd = NULL;
int report = 0;
char tmp;
if (argc != 3) usage();
if (!strcmp(argv[2], "up")) {
cmd = "./ifup";
} else if (!strcmp(argv[2], "down")) {
cmd = "./ifdown";
} else if (!strcmp(argv[2], "report")) {
report = 1;
} else {
usage();
}
if (chdir("/etc/sysconfig/network-scripts")) {
fprintf(stderr, "error switching to /etc/sysconfig/network-scripts: "
"%s\n", strerror(errno));
exit(1);
}
/* force the interface configuration to be in the current directory */
chptr = ifaceConfig = argv[1];
while (*chptr) {
if (*chptr == '/')
ifaceConfig = chptr + 1;
chptr++;
}
/* automatically prepend "ifcfg-" if it is not specified */
if (strncmp(ifaceConfig, "ifcfg-", 6)) {
char *temp;
temp = (char *) alloca(strlen(ifaceConfig) + 7);
strcpy(temp, "ifcfg-");
/* strcat is safe because we got the length from strlen */
strcat(temp, ifaceConfig);
ifaceConfig = temp;
}
if(getuid() != 0)
switch (userCtl(ifaceConfig)) {
char *dash;
case NOT_FOUND:
/* a `-' will be found at least in "ifcfg-" */
dash = strrchr(ifaceConfig, '-');
if (*(dash-1) != 'g') {
/* This was a clone configuration; ask the parent config */
tmp = *dash;
*dash = '\0';
if (userCtl(ifaceConfig) == FOUND_TRUE) {
/* exit the switch; users are allowed to control */
*dash = tmp;
break;
}
*dash = tmp;
}
/* else fall through */
case FOUND_FALSE:
if (! report)
fprintf(stderr,
"Users are not allowed to control this interface.\n");
exit(1);
break;
}
/* looks good to me -- let's go for it if we are changing the interface,
* report good status to the user otherwise */
if (report)
exit(0);
/* pppd wants the real uid to be the same as the effective (god only
knows why when it works fine setuid out of the box) */
setuid(geteuid());
execle(cmd, cmd, ifaceConfig, NULL, safeEnviron);
fprintf(stderr, "exec of %s failed: %s\n", cmd, strerror(errno));
exit(1);
}
|
